Actual Work Research Articles

Investigation of corrosion resistance and interfacial bonding properties of silver/silicone zinc-rich coating/substrate system in marine environment

This paper aims to study the corrosion resistance and interfacial bonding properties of the silver zinc-rich coating/substrate system and silicone zinc-rich coating/substrate system. The actual working state of the system in marine environment was simulated by the coupled effects of corrosion and pre-stretching. Scanning electron microscope (SEM) with an energy dispersive X-ray spectrometer (EDS) was used in corrosion test to analyze the surface morphology and corrosion products. Meanwhile, the degradation degree of the corrosion resistance was investigated based on the electrochemical impedance spectroscopy (EIS) and water absorption rate. Three-point bending test and tensile test combined with digital image correlation (DIC) were performed to evaluate the interfacial bonding properties of these two systems based on the elastic modulus and critical cracking strain. Results show that the dense accumulation of aluminum and zinc powders makes the silver zinc-rich coating have higher corrosion resistance compared to the silicone zinc-rich coating. The combined effects of corrosion and pre-stretching on the fracture toughness of silicone zinc-rich coating are larger than that of the silver zinc-rich coating. The interfacial bonding properties of the coating/substrate systems gradually degrade as the pre-stretching load approaches the critical cracking load of the coating.

Social accountability in a medical school: is it sufficient? A regional medical school curriculum and approaches to equip graduates for rural and remote medical services

BackgroundSocial accountability is increasingly integral to medical education, aligning health systems with community needs. Universitas Pattimura’s Faculty of Medicine (FMUP) enhances this through a curriculum that prepares graduates for rural and remote (RR) medical practice, exceeding national standards. The impact of this curriculum on graduate readiness in actual work settings remains unassessed.ObjectiveThis study was conducted to capture the perspectives of FMUP medical graduates in a rural-centric curriculum, focusing on the teaching and learning opportunities afforded to them during their medical education. These insights are crucial for evaluating the accountability of regional medical schools in delivering quality service, particularly in underserved areas.MethodsSemistructured interviews were conducted with nine FMUP graduates employed in the RR areas of Maluku Province. A qualitative analysis was employed to examine graduates’ views on the curriculum concerning medical school accountability.ResultsThe FMUP curriculum, informed by social accountability principles, partially prepares graduates to work under Maluku’s RR conditions. However, it was reported by participants that their skills and preparedness often fall short in the face of substandard working environments.ConclusionsThe FMUP curriculum supports the government’s aim to develop an RR medical workforce. However, the curriculum’s social accountability and rural emphasis fall short of addressing community health needs amid inadequate practice conditions. Political investment in standardizing medical facilities and equipment is essential for enhancing graduates’ effectiveness and health outcomes in RR communities.

Dynamic breakthrough performance of low concentration CO2 adsorption in fixed-bed column with porous amino acid ionic liquid composites

Low concentration carbon dioxide (CO2) capture from air or confined spaces currently faces significant challenges, such as relatively poor dynamic adsorption breakthrough performance and cyclic stability. In our previous work, functionalized ionic liquid (IL) tetraethylammonium glycine ([N2222][Gly]) and porous molecular sieve (SBA-15) were combined to synthesize porous amino acid IL composite 60 wt% [N2222][Gly]@SBA-15 with microporous and ultra-microporous structures, which provide a new pathway for low concentration CO2 capture. In order to further obtain the dynamic CO2 adsorption breakthrough performance of this material under simulated actual working conditions, the effects of temperatures, relative humidity (RH) and CO2 concentrations on CO2 adsorption and desorption breakthrough performance of 60 wt% [N2222][Gly]@SBA-15 in a fixed-bed column were systematically studied in this work. The results indicated that CO2 adsorption capacity is up to 1.81 mmolCO2/g-adsorbent at 298.15 K, 1 bar and 0 % RH under 1 vol% CO2-containing gas mixture balanced with N2 and reaches 2.44 mmolCO2/g-adsorbent at 15 % RH due to the mechanism change of CO2 reaction with primary amine from 2: 1 under dry gas to 1: 1 stoichiometry in the presence of moisture. Moreover, the adsorbent maintains good cyclic adsorption-desorption performance. Further, CO2 adsorption breakthrough behaviors were well fitted by Avrami kinetic model, and the CO2 adsorption rate of 60 wt% [N2222][Gly]@SBA-15 was controlled by intra-particle diffusion. This work implied that IL-modified adsorbents have great potentials for low concentration CO2 capture applications.

Dynamic identification of coupler force of heavy haul locomotive: An effective and long-term intelligent measurement method

Longitudinal impulse, as a common dynamic problem of heavy haul trains, could induce the lateral instability of the coupler and the separation of the locomotive and wagon connection and thus seriously hinder the train running safety. The coupler force undergoes complex changes during longitudinal impulse transmission and exhibits strong nonlinear characteristics, which poses significant challenges to the identification of the coupler force. To address these issues, this paper reports a novel quantitative method for the coupler force identification of heavy haul locomotives. Firstly, the moving average filtering method is used to preprocess the signal of longitudinal relative displacement between the coupler and carbody (LRDCC), and the approximate relative velocity (ARV) feature is also extracted from the preprocessed signal. Then, a Convolutional Neural Network (CNN) model is constructed to extract high-level features from LRDCC and ARV. The model with randomly initialized weight parameters does not require additional training and thus reduces the computational cost. Finally, an Extreme Learning Machine (ELM) is used as the regression layer to process the extracted high-level features and further improve the identification performance. Additionally, the dung beetle algorithm is used to obtain the optimal model parameters to improve the coupler force identification performance. Not only a dynamics simulation but a field test is carried out to show that the proposed method could accurately detect the coupler force of heavy haul locomotives. Furthermore, the proposed method shows promising prospects in replacing the traditional monitoring method under the actual long-term working conditions of trains.

Novel approaches to monitoring the formation of self-assembled colloids composed of cationic surfactants and alginate polysaccharide

In actual work, the self-assembly process of alginate (Alg) polysaccharide having low molecular weight (240 kDa) with cationic surfactants from the family of trimetylammonium bromide (TAB) derivatives was investigated at wide polysaccharide/surfactant molar ratio range through the interpretation of the formation of non-aggregated colloidal complexes.On one hand, the critical micelle concentration (cmc) values of the studied TAB surfactants having C12C18 chain length were determined and published for the first time in phosphate buffer solution. In addition to the applied conventional measurement procedures like tensiometry, light scattering, calorimetry, and equilibrium dialysis-based methods, the applicability of streaming potential technique was also demonstrated for the first time for these types of systems to gain a deeper insight into the formation process of the complexes built up by biocompatible polysaccharides and cationic surfactants. Through the interpretation of the change of the streaming potential values as a function of increasing surfactant's concentration it was clearly highlighted that both the individual and cooperative binding process of the surfactants can be clearly identified followed by the aggregation of the polysaccharide-surfactant colloidal complexes and the formation of surfactant micelles in the bulk dispersion.

A Questionnaire Survey of Nurses on Pharmacist Services in the Emergency Rooms at Tokushukai Medical Group

We conducted a multicenter survey of emergency room nurses to obtain information that would be useful for the establishment of pharmacist services in emergency rooms. Notably, 199 valid responses were obtained from 12 hospitals. The most common expectation from pharmacists in the emergency room was "drug management" (70.9%), followed by "providing information to physicians regarding the patient's medication history" (59.3%), and "auditing of dosage and interaction" (57.3%). The working arrangements that the survey respondents wanted regarding pharmacists in emergency rooms were: 24 h pharmacist (41.7% wanted this arrangement), day-shift pharmacist (24.6% wanted this arrangement), 24 h on-call (17.1% wanted this arrangement), day-shift on-call (5.0% wanted this arrangement), telephone support (11.1% wanted this arrangement), and 0.5% said that there was no need for pharmacists. In the analysis of factors affecting nurse satisfaction, day-shift pharmacist was a significant factor. We hope that the results of this survey will be used as a guide for the development of emergency room pharmacist services tailored to the unique characteristics and actual working conditions of each hospital.

Multi-objective optimization and energy efficiency improvement for rotor duct in integrated energy recovery-pressure boost device

To reduce the volumetric mixing rate of the integrated energy recovery-pressure boost device, a novel symmetrical duct structure with diversion surface was proposed. The surrogate model-based multi-objective optimization framework was established, and obtained the optimal ducts V1 and V2 combined with computational fluid dynamics simulation. Numerical results indicate that optimized duct structure could promote the formation of plug flow and effectively improve the collision efficiency between high-pressure brine and low-pressure seawater, and the volumetric mixing rate corresponding to the ducts V1 and V2 was reduced by 31.52% and 22.18%, and the duct volume efficiency was increased by 16.04% and 19.56%, respectively. Finally, the performance of optimized device was verified through seawater reverse osmosis desalination system under actual working conditions. Experimental results showed that the mixing rate of optimized ducts had a significant decrease of 30.86% and 20.53% in the applicable range, and the energy recovery efficiency improved at most 5.41% and 7.55%, respectively. The optimized ducts could significantly reduce the specific energy consumption of the desalination system by 26.01% and 18.22%, respectively, and the specific energy consumption reached the lowest level of 3.02 kWh/m3, demonstrating the superiority of the structure and the accuracy and effectiveness of the optimization strategy.

Semi-supervised few-shot fault diagnosis driven by multi-head dynamic graph attention network under speed fluctuations

Although graph neural networks (GNNs) have achieved great success in the field of semi-supervised bearing fault diagnosis recently, most GNN-based studies still face the challenge of insufficient labeled samples. Meanwhile, the signals collected from bearings usually have a time offset due to the alternating speed in the actual working conditions, reducing the applicability of traditional GNN diagnosis methods relying on Euclidean distance. And incomplete use of unlabeled data and insufficient exploitation of neighborhood information further reduce the reliability of fault diagnosis models. To solve these problems, a semi-supervised few-shot fault diagnosis method driven by multi-head dynamic graph attention network (MHDGAT) is proposed in this study. First, dynamic time warping (DTW) similarity is introduced in the construction of K-nearest neighbor graph to solve the problem of local time offset caused by speed change. Second, some pseudo labels generated by smoothness assumption are injected into the raw training set, and more comprehensive information can be learned in the process of model training. Then, the presented MHDGAT model can mine rich fault characteristics from different scales by the multi-head attention and extract the most sensitive features due to the proposed dynamic graph mechanism adaptively. Finally, the fault categories can be obtained by a softmax classifier located at the end of the model. The proposed model has been validated in two case studies, and the experimental results indicate that MHDGAT exerts strong performance even under extremely low-label ratios.

Design and support performance evaluation of medical multi-position auxiliary support exoskeleton mechanism

Aiming at the status of muscle and joint damage caused on surgeons keeping surgical posture for a long time, this paper designs a medical multi-position auxiliary support exoskeleton with multi-joint mechanism by analyzing the surgical postures and conducting conformational studies on different joints respectively. Then by establishing a human-machine static model, this study obtains the joint torque and joint force before and after the human body wears the exoskeleton, and calibrates the strength of the exoskeleton with finite element analysis software. The results show that the maximum stress of the exoskeleton is less than the material strength requirements, the overall deformation is small, and the structural strength of the exoskeleton meets the use requirements. Finally, in this study, subjects were selected to participate in the plantar pressure test and biomechanical simulation with the man-machine static model, and the results were analyzed in terms of plantar pressure, joint torque and joint force, muscle force and overall muscle metabolism to assess the exoskeleton support performance. The results show that the exoskeleton has better support for the whole body and can reduce the musculoskeletal burden. The exoskeleton mechanism in this study better matches the actual working needs of surgeons and provides a new paradigm for the design of medical support exoskeleton mechanism.

Study on dynamic response and long-term settlement of silty soil around Shanghai metro tunnel

At present, the method for calculating long-term tunnel settlement predictions under metro loading considers only one working condition of passenger loading, which is inconsistent with actual working conditions. To establish a tunnel settlement model that accounts for variations in passenger flow, this study uses data mining methods to categorize metro operation into three working conditions: "peak period, secondary period, and low period." The impact of these passenger flow conditions on the dynamic response of the soil around the tunnel is analyzed. Then, based on the principles of calculus, a calculus-based prediction model is established to consider the changing patterns of metro passenger flow. The model is applied to analyze the long-term settlement characteristics of Shanghai Metro Line 10. The results indicate that, under identical conditions, soil displacement and dynamic deviatoric stress around the tunnel increase with passenger capacity. The calculus prediction model aligns more closely with actual working conditions than the conventional model. The predicted tunnel settlement of Shanghai Metro Line 10 after 20 years of operation is approximately 37.07 mm, with most settlement occurring in the early stages, primarily due to cumulative plastic deformation of the soil.

Dirichlet probability navigated fault detection via key-group memory auto-encoder under non-stationary working conditions

Real-time condition monitoring is the foundation of prognostics and health management (PHM) for mechanical systems. Constraint by extravagant cost and insurmountable obstacles to simulate real faults in actual working conditions, establishing fault detection models with historical normal data is the most promising way. Meanwhile, non-stationary fault detection is rarely studied in the literature but fits most in real working conditions. Thus, an innovative method named KGMem-DirAE is proposed to conduct real-time fault detection under non-stationary working conditions using normal data only. In the training stage, normal patterns with different semantics are recorded in the developed key-group memory module (KGMem) combined with auto-encoder. Considering the matching probabilities of encoded latent features and recorded memory units (normal patterns), a statistical anomaly score defined by aggregated negative log-likelihood of Dirichlet distributions is proposed to detect incipient failures. In order to deal with time-varying working conditions and capture fault degradation trends concurrently, normalized time-frequency maps containing fault-evolving information are obtained from vibration data. Both widely studied non-stationary and stationary run-to-failure data sets are deeply researched using the proposed KGMem-DirAE and the experimental results proved its superiority against other comparative anomaly detection methods.

Application of Finite Element Algorithms for Formula Racing Steering Wheels

The steering wheel of a Formula Student car has an important influence on the driving and handling stability of the car. The steering wheel of the racing car must have good mechanical and stable performance, taking into account lightweight and economic performance. Due to the small riding space of the car, the size of the steering wheel is not required to be too large. In this case, it is very difficult to meet its harsh stress state and control its vibration and noise. Based on the general requirements of the competition rules of the Formula Student racing competition, this paper constructs the geometric model of the steering wheel of the racing car by using the computer 3D design software CATIA. ANSYS software was used to conduct finite element analysis of the mechanical properties of the metal skeleton of the steering disc. Magnesium alloy, a light material with excellent mechanical properties, was selected, and combined with the actual working conditions of the steering disc, especially the force under extreme conditions, the computer simulation results showed that the force distribution and displacement of the steering disc met the design requirements. Considering that the noise and vibration of the steering wheel will have a great impact on the racer, the modal analysis of the steering wheel is carried out by using ANSYS software, and the analysis results show that there is no resonance or instability.

Research on the calculation and evaluation method of transmission efficiency of noncircular planetary gear

The torque fluctuation characteristics of noncircular planetary gear (NPG) systems are difficult to obtain, and there is no clear analysis method and evaluation method for transmission efficiency, which seriously affects their service performance. Given that, this article establishes a torque fluctuation model for NPG systems based on the principle of gear meshing and differential geometry theory and methods, taking into account factors such as actual working conditions and speed loads. And proposed, the comprehensive transmission rate, a new method for evaluating the efficiency of NPG systems. By analyzing the actual working conditions of NPG systems, the influence mechanism of alternating load and speed on torque fluctuation and transmission efficiency was explored. The research results indicate that the alternating load can cause an increase in system impact and vibration. The comprehensive transmission rate of NPG systems decreases with increasing rotational speed and increases with increasing load, and is more sensitive to changes in rotational speed. The trend of comprehensive transmission rate and transmission efficiency of NPG systems is basically consistent, indicating that the proposed method of using comprehensive transmission rate to evaluate transmission efficiency is a practical and feasible analysis method. The research results can provide a new method for dynamic measurement and evaluation of torque and transmission efficiency of non-circular gear transmission systems.

Temperature damage assessment of mass concrete based on the coupling mechanism of hydration-temperature-humidity-constraint factors

Temperature cracking of mass concrete is an important issue affecting the safety of concrete foundations in civil engineering. This problem extends from the construction process of concrete foundations to the operation stage. This study uses low-temperature-rising (LTR) polymers to regulate the hydration process of cementitious materials, and prepares LTR mass concrete. Taking the hydration degree of concrete-cement system as the basic state variable, the multi-factor effects of actual hydration process, temperature, humidity changes, and constraints on mass concrete are comprehensively considered. A concrete temperature-damage model based on the coupling mechanism of “hydration-temperature-humidity-constraints” is established, and the temperature, stress, and temperature damage evolution laws of LTR mass concrete and ordinary mass concrete are calculated. The reliability of the model is verified through field tests. The results show that the finite element method can effectively simulate the development of concrete temperature, stress, and damage degree based on actual working conditions under multi-factor coupling.

Material system and tribological mechanism of plasma sprayed wear resistant coatings: Overview

Challenging environments in aviation, automotive, electric power, and various industrial sectors are increasing industry and technological demands, resulting in machine damage and energy loss from friction and wear between interacting surfaces. Addressing this issue requires the development of new and advanced materials, processing techniques, and surface modification methods to enhance performance and reduce friction and wear. Plasma spraying technology is essential for material surface reinforcement and modification because of its low cost and stability. This paper reviews and summarizes the research progress on plasma spraying wear-resistant coating material systems and tribological mechanisms, covering the working process and principles of plasma spraying equipment. It also details wear-resistant coating material systems, including iron-based, nickel-based, copper-based, other metal materials, oxides, and monoxide ceramic materials.Furthermore, it addresses the wear-resistant and friction-reduction mechanisms of wear-resistant coatings, aiming to summarize the tribological strengthening mechanism concerning wear resistance and friction reduction. Moreover, this paper covers aspects such as powder design, sealing treatment, laser remelting, and other methods for regulating the wear resistance of coatings, examining their influence on the wear resistance of coatings in material design, spraying process, and post-spraying treatment. Plasma spraying wear-resistant coatings should be used along with doping modification and other methods to study the new spraying materials; furthermore, the optimization of the spraying process and post-treatment methods should be investigated to prepare a wear-resistant coating that meets the performance of the actual working conditions. At the same time, ultrahigh temperature wear-resistant coatings and super lubricating coatings are also future research priorities. In addition, when comparing plasma transfer arc spraying technology and plasma enhanced high-speed arc spraying technology with plasma non-transfer arc spraying technology, the jet temperature is higher, and the cost is lower; however, since the process is still in its infancy, the follow-up should be strengthened in this area of technical research. This paper provides a theoretical basis and reference for researching plasma spraying wear-resistant coatings in various fields.

Damage and fracture investigation of self-compacting concrete in the filling layer of CRTS-III using three-point bending tests

Literature about filling layer self-compacting concrete (FLSCC) has indicated that FLSCC plays a crucial role in its application to Chinese railway track system III (CRTS-III). It is apparent that the damage characteristics of FLSCC have not been clearly investigated, as the actual working conditions are not considered enough. There exists a remaining gap about the mechanical properties and fracture behaviors of FLSCC under bending loads. In order to fill this gap, in this study, three-point bending (TPB) tests on the FLSCC beams with precast notches were performed based on the real bending situation of FLSCC in CRTS-III. Acoustic emission (AE), strain gauges and a digital camera were utilized to monitor the fresh evolutionary laws of micro- and macro-cracks as well as the corresponding damage morphology. The study presents that the monitored load-crack mouth opening displacement (P-CMPD) curves, load-strain (P-ε) curves and AE activity curves all exhibited similar distributions, including four stages with increasing bending loads. In term of the AE activities, the first apparent crack in the interior and warning point of failure can be detected by analyzing the captured AE activities of the FLSCC beams. In addition, the dominant failure mode of the specimens was determined as tensile cracks according to the rising angle-average frequency (RA-AF) criterion for potential FLSCC application in terms of the limiting ratios. This failure mode indicates that under pure bending loads, the mid-span section is subjected to the maximum bending moment, and the specimen experiences tensile damage. Therefore, for future practical application, the structural health state of FLSCC in CRTS-III could be nondestructively real-time monitored by the AE technique. Meanwhile, the calculated fracture parameters of the FLSCC specimen can reflect the cracks stability of the specimen. This study can also present experimental and theoretical references for further studies on FLSCC in CRTS-Ⅲ under other types of loads.

Construction and simulation of a joint scale model for power electronic converters based on wavelet decomposition and reconstruction algorithms.

In power electronics systems, system design and operation often involve multiple time and space scales, ranging from nanosecond switching dynamics to hour-level system operation behavior. Due to the complexity of these systems and the rise of wide-gap semiconductor technology, a series of multi-scale phenomena have emerged that are difficult to ignore. The high frequency of switching operations makes multi-scale effects particularly significant, including the fast dynamic response of the power loop, EMI, and heat conduction problems. They are key factors that must be considered in the design to ensure the efficient and reliable operation of power electronic devices. This study proposes the construction and simulation of a joint scale model for power electronic converters based on wavelet decomposition and reconstruction algorithms to address the multi-scale phenomenon and limitations of single-scale power electronic converters. Firstly, a joint scale model for power electronic converters at both macro and micro-scales was established, targeting both single-scale models and simple combinations of multiple scale models for power electronic converters. The traditional single-scale model is sufficient to describe the average behavior of the converter, but it has serious limitations in capturing fast transient processes and high-frequency switching behavior in power electronic systems. These limitations often manifest themselves when there is a need to capture fine timescales of detail. By transforming between the time domain and the frequency domain, wavelet decomposition enables the model to capture both macroscopic average characteristics and microscopic transient dynamics. The wavelet reconstruction algorithm can simulate all kinds of fast changes in the actual working process more accurately and compress irrelevant information while retaining key signal features, so as to optimize the simulation performance of the model. Secondly, this algorithm is used to analyze BC in short time scale. Finally, the short time scale characteristics of power electronic converters are analyzed. Experimental results show that the fusion of wavelet decomposition and reconstruction algorithm enhances the accuracy of the power electronic converter model and improves the performance of the system. The model achieves an error reduction of nearly 3% in the calculation step size of 10-7s, which has a significant impact on the high precision requirements of high-frequency operations. In addition, the optimal calculation step size of 8×10-8s achieves an error reduction of more than 14%, making an important contribution to the transient analysis and fine structure simulation. The wavelet algorithm can improve the accuracy of multi-scale modeling in power electronic system and reduce the simulation time. The reduction of error not only shows the improvement of the accuracy of the model, but also shows its practical significance in the design and test of the actual power electronic system. The reduction in error reveals the ability to more accurately predict and mitigate potential performance problems in matching tests with actual hardware, as well as its ability to adapt to emerging wide bandgap semiconductor materials and structures.

Failure and Damage of Reciprocating Lip Seals for Pneumatic Cylinders in Dry Conditions

Lip seals are components subjected to high mechanical stress and they are responsible for many out-of-service in pneumatic cylinders. The aim of this work is the development of an experimental methodology to evaluate lifetime duration and analyse failures and damages of rod lip seals for pneumatic cylinders. A dedicated test bench was designed and manufactured which reproduces actual working conditions of the seals i.e., compressed air action (seal pressurisation) and relative linear reciprocating motion. Three types of seals made of two elastomers (NBR and polyurethane) were tested; dry condition was considered to speed up the tests. The influence of geometric parameters like seal seat dimension and seal axis misalignment with respect to the rod axis, was analysed by multiple experimental tests. Results in terms of seal life duration and failure modes are presented which allow comparison of seals performance and provide a helpful tool to end-users in a proper selection of seals geometry, material and key working parameters.

Evaluation of overall equipment effectiveness (OEE) for mining equipment (shovel-truck): A case study Manisa-Soma (Turkey) open pit mine

Mining is a costly activity that requires huge investments and large equipment. Therefore, it is crucial to use mining equipment efficiently to maximize productivity. This requires the continuous analysis of equipment efficiency and taking action to reduce negative impacts. Accurately estimating equipment efficiency is essential to increase its effectiveness. One globally recognized and accepted measurement is Overall Equipment Effectiveness (OEE). In this study was conducted to calculate the OEE values of shovels and trucks, which are the primary equipment used in open pit mining. The study presented different loss times and quality values while calculating the OEE values of mining equipment. The OEE values of electric trucks and shovels were found to be consistent with actual work quantities in the Manisa-Soma Lignite open pit operation. This study is the first applied study of OEE analysis in Turkey.

근로시간 제도의 유연화를 위한 과제

The ”work hours” are the key terms and conditions of employment in the labor contract (Labor Standards Act Article 17-1(2)), and they are closely related to the “wages” paid to the worker as remuneration for work. The main task of the Labor Act is to regulate the work hours to protect the health rights of workers and guarantee the work-life balance of the workers. The history of Labor Act is also called the history of shortening the work hours. This is because the work hours are the key regulatory matters in the Labor Act. It is also a crucial task to regulate the work hours to guarantee the health rights and living rights of the workers.
 The Korean work hour system is mainly based on the Labor Standards Act. Since the enactment of the Labor Standards Act in 1953, the discussions and changes regarding the work hour system have been focusing on reduction of the legal work hours and standard work hours to secure the recess rights or health rights of the workers. For example, the initial work hours of Korea reduced from eight hours a day and 48 hours a week (Labor Standards Act enacted on May 10, 1953) to eight hours a day and 44 hours a week in 1989 (Labor Standards Act amended on March 29, 1989). Since 2003, the work hours have been reduced to eight hours a day and 40 hours a week (Labor Standards Act amended on September 15, 2003) until now. Provided, the work hour system under the current Labor Standards Act mainly regulates the actual work hours and fails to consider the living time of the workers.
 The work-life balance has been recently spotlighted, and there is a growing demand for flexible work hours. In fact, flexible work hour is a key issue in many workers for work-life balance, and flexible work hour is considered as a main mean to improve the work-life balance.
 The guarantee of time needed for family life and social life may vary depending on the individual circumstances of each work. In order to improve the work hour system, it is necessary to secure the right to decide the allocation and placement of the work hours in consideration of the individual worker demands based on the labor-management agreements.
 In reformation of the work hours, the total amount of work hour should be continuously reduced and regulated while guaranteeing flexibility in operation of the work hour within the total amount. The current laws and systems also need to be reviewed again based on these perspectives. Furthermore, individual and fragmentary improvement of the work hour system cause inefficiency and lack of practicality in system operation. Thus, it is necessary to redesign the realistic and future-oriented work hour regulation framework.