High Protrusion Research Articles

Association between cup fixation screw and iliopsoas impingement after total hip arthroplasty

BackgroundIliopsoas impingement after total hip arthroplasty can result not only from acetabular cup but also from cup fixation screw. However, research addressing this screw impingement is scarce, leaving the details undetermined. This study aimed to elucidate the incidence and threshold of symptomatic iliopsoas impingement attributable to protrusion of the cup fixation screw into the iliopsoas muscle and to evaluate its impact on postoperative radiographic imaging findings and patient-reported outcome measures. MethodsA total of 152 hips were included in this study. The symptomatic threshold of screw protrusion was determined using a receiver operating characteristic curve, and patients were divided into low-protrusion and high-protrusion groups using this threshold. The area and Hounsfield Unit values of the iliopsoas muscle on CT and the Japanese Orthopaedic Association Hip Disease Evaluation Questionnaire postoperatively were investigated. Findings10 hips (6.5%) were exhibited symptoms of IPI in this series. The threshold for screw protrusion length was identified as 6.4 mm. Patients in the high protrusion group exhibited significantly larger area and lower Hounsfield Unit values of the iliopsoas muscle. In addition, the high protrusion group revealed significantly lower scores (total, pain, movement, mental). Furthermore, subscales scores (pain, movement) in the high protrusion group didn't improve from 3 months to 12 months postoperatively with significance. InterpretationThis study underscores the imperative for surgeons to consider the length of the cup fixation screw. This careful consideration is crucial for mitigating the incidence of postoperative iliopsoas impingement and enhancing total hip arthroplasty outcomes.

A rapid dual-drive technology for extinguishing large high-gas coal mines fires

Fires formed by the high gas protrusion in coal mines are difficult and risky to extinguish during the mine closure process due to the mine’s large closed range and underground gas stock. To achieve efficient and safe unsealing, reduce the risk of re-ignition and gas explosion, and accurately determine the fire extinguishing effect, a dual-drive rapid fire extinguishing technology is proposed. This technology involves ground precise positioning of drilling holes, rapid and large flow of liquid nitrogen injection, and curtain grouting to block fires in ultra-large high-gas mines. The practical results demonstrate that the implementation of surface injection of liquid nitrogen for fire extinguishing and cooling, and plugging effectively reduces the concentration of CO in the underground space from 230 PPm to 0 PPm, and decreases the CH4 concentration content from 90% to less than 0.75%. The fire extinguishing and cooling effect is fast and significant. A technical scheme for unsealing the fire area of the whole mine is formulated on a large scale based on the state of pumping and releasing pressure in the closed space of the mine. This scheme has important guiding significance for safety rescue and rescue operations after serious fire accidents occur in similar high-gas prominent mines.

Process and Design Challenges for Hybrid Bonding

Hybrid bonding is one of the key technology to enable solutions for high bandwidth with increasing power and signal integrity. Hybrid bonding involves, face-to-face interconnect formation between wafers and it acts as an extension of fusion bonding technology. Wherein, dielectric materials such as silicon dioxide bond at room temperature and the copper vias embedded in the dielectric expand to form the electrical connections, enabling the interconnect formation between the top and bottom wafer.Hybrid bonding provides advantages over traditional C4 flip-chip bonding involving solder-based micro-bumps, such as, interconnect pitch scaling to less than 10 µm thereby providing higher interconnect density and increased power and signal speed efficiency for memory and high-performance computing application along with better reliability. It is compatible with standard CMOS fabrication technology.In this work, we would like to present the design and process challenges which may lead to improved bonding yield. To enable hybrid bonding with high yield it is necessary that the bonding surfaces are flat with low roughness. The optimized chemical mechanical polishing (CMP) process is one of the key process technology which enables surface topography to be less than 10 nm and surface roughness to be less than 0.8 nm. The surface topography is dependent on the metal via layout, interconnect density and the surrounding dielectrics and hence, these design parameters act as a guiding principle for the application-oriented definition of the design to accommodate different pitch sizes of interconnecting vias (from 1 µm to 10 µm). The mechanical properties of the materials play a key role as well as this will define the removal rate of dielectric and the metals during the CMP process which will affect the dishing and the surface topography. To achieve high bonding yield the surface topography is key as this will affect the bond front propagation and hence the bonded and non-bonded region between the dielectrics. To further improve the bonding yield we have applied a tailored annealing recipe which improves the bonding yield significantly. This paper would focus our work on topography improvement and overall bonding yield in detail and a comparison of bonding yield with and without dummy vias. Dummy vias in this context refer to the copper via structures that are not intended for interconnect formation but are there for CMP process optimization to achieve better process control. Hence, the dummy vias are not connected to the underlying routing metal layer.Figure 1, shows an ideal surface that would result in W2W bonding with high yield. Figure 2 shows, the defects such as high copper dishing, copper protrusion, dielectric erosion and poor surface topography which will result in poor bonding yield. Figure 3 shows the bonding using SiON as the bonding dielectric with (a) without dummy copper vias (~98% bond yield) and (b) with dummy copper vias (~88% bond yield). Figure 1

Influence of wire electrical discharge conditioning on the grinding performance of metal-bonded diamond grinding tools

Wire Electrical Discharge Conditioning (WEDC) is an efficient non-conventional method for conditioning metal, resin, and hybrid bonded super-abrasive grinding tools. Since the diamond and CBN grains are not affected directly by the WEDC and only the electrically conductive bond material is eroded by the process, high grain protrusions are achievable. Therefore, unlike the common mechanical conditioning methods using WEDC, the microtopography of the grinding tool can be influenced by the process parameters, directly affecting the grinding efficiency. However, the selection of WEDC process parameters is influenced by the specifications of the grinding tool, particularly the grain size and concentration. This study aims to investigate the effects of WEDC parameters and strategies on the microtopography and material removal rate of metal-bonded grinding tools, considering different grain sizes and concentrations. Additionally, the correlation between the microtopography of grinding tools conditioned by the WEDC process and their grinding efficiency was investigated by analyzing tool wear, grinding forces, and surface roughness of tungsten carbide workpieces. The results indicate that the material removal rate of the WEDC process decreases as the grain size and concentration of metal-bonded diamond grinding tools increase. Furthermore, it was observed that employing high spark energy parameters reduces the grain protrusion of grinding wheels with small grain sizes. However, the utilization of high-energy sparks is necessary to create larger spark gaps and achieve a higher material removal rate.

Microstructure and properties at bonds of diamond grains and Ni[sbnd]Cr filler alloy by fiber laser brazing

Advanced laser technology has been used in laser brazing to bond diamond grains in metal matrix to achieve some distinctive advantages such as high protrusion heights and large gaps of diamond grains. However, laser brazing has not been widely adopted as expected to produce various diamond tools since that bonding mechanisms, microstructures and characteristics of bonded interfaces have not fully investigated. In this paper, the experimental study was performed for using fiber laser brazing to bond diamond grains on steel substrate with NiCr filler alloy. Microstructures, graphitization, and shear force at the bonded interface were especially analyzed. The experiments led to the following outcomes: (1) the interface of diamond grains and NiCr alloy was a wavy surface with an average thickness of 7 μm. (2) Two types of carbide, i.e., Cr3C2 and Cr7C3, were generated on the brazed surface; Cr3C2 was lath-shaped and generated at first, and Cr7C3 was prismatic and built upon Cr3C2. (3) The interface of diamond grains and NiCr alloy was rough and accompanied by graphitization. (4) The shearing test showed that an average force of 138 N was applied to debone single diamond grain from filler metal.

Development of an On-Line Defect Detection System for EDM Process

In the electrical discharge machining process, preliminary research has been able to effectively estimate machining accuracy in response to its long machining history and high discharge frequency characteristics. However, when processing abnormalities occur, it is difficult to identify them since the electrical discharge process contains multiple processing parameters, which increases the cost of repair or loss afterwards. Therefore, the question concerning how to monitor the abnormality of the discharge process in real time represents the main purpose of this research. This research develops an EDM process abnormal diagnosis system. First, the data are stored in a circular array to speed up the processing time, and the coefficient of variation feature is added, which has effectively extracted the abnormal characteristics. In terms of diagnostic methods, the composite voting model established by neural networks, random forests, and XGB-RF (extreme gradient boosting applying RF) can provide robust diagnostic results. Finally, through the Node-RED webpage and MQTT agreement, it can provide the ability to monitor machine abnormalities in real time. Through refinement and optimization of the previous research results, this study took the electrical discharge machining diamond grinding wheel as an example, and developed a warning that can be issued within 3 min when abnormalities (abnormal patterns such as polycrystalline diamond high protrusions) occur, with an accuracy of 93% and a false positive rate. The abnormal diagnosis ability is less than 0.2%. Therefore, the online abnormality monitoring system developed by this research institute will be able to provide online abnormality diagnosis for electrical discharge machining.

A case of primary immune thrombocytopenia occurring asymptomatic cerebral embolism and in-stent high echoic protrusion after carotid artery stenting

A case of primary immune thrombocytopenia occurring asymptomatic cerebral embolism and in-stent high echoic protrusion after carotid artery stenting

Misunderstanding on germination sensu stricto leads us to a false positive germination‐dormancy balance in diaspores of Paepalanthus chiquitensis Herzog (Eriocaulaceae), a threatened everlasting flowering species

AbstractAlthough germination sensu stricto and germination–dormancy balance are essential to each other, few reports demonstrate the effects of their relationship on patterns of seed–seedling transition. We studied this relationship by using diaspores of Paepalanthus chiquitensis, a threatened everlasting flowering species. We assessed three aspects: (a) water dynamics in germinating diaspores, (b) thermal stimulation (35, 40, 50, 60 and 70°C for 30 min) and (c) imbibition (4 hr) in growth stimulators (100, 200 or 300 mg · L−1 GA3; 0.1% KNO3). Our findings demonstrate that there are no barriers in the diaspore for diffusion. Additionally, there is high variability in diaspore permeability, and the germination of the species has two steps divided into five stages. These stages were defined by inflections on velocity in water dynamics, which ranged from −0.05 to 0.05 g · hr−1, where only the last stage (Phase V) is associated with the second step of germination sensu stricto. The imbibition phase was the shortest germination phase (1.3 hr), whereas the predominantly biochemical phase was the longest (5 days after sowing [DAS]). Germinability was high (77.5–86.5%), with high daily embryo protrusion (2.46–3.03 diaspores · day−1). Protocorm emergence marked the end of the first step of germination sensu stricto (9 DAS), and first protocorm rupture (11 DAS) marked the end of the second step. The growth stimulus only concentrated the germination process, showing that the diaspores do not have primary dormancy. Knowing these diaspores’ peculiarities during germination sensu stricto avoids a false positive statement on the existence of diaspore dormancy.

Wear characteristics of diamond segments on multi-blade combination saw with different diameters in granite sawing

In this paper, the wear characteristics of diamond segments adopted to multi-blade combination circular saw with different diameters were compared and investigated in the process of granite through an experiment. Load model with a diameter as the variable of combination saw was established based on the maximum undeformed chip thickness of a single particle. Combined with the load model, scanning electron microscope, laser microscope and vernier calipers were used to comprehensively analyze the wear characteristics of segment form the aspects of the wear morphology of diamond and metal matrix, the particle protrusion height, and the abrasion loss of segment. The results indicated that load nonuniformity of diamond generated by diameters change of saw blade was the main reason for segment wear discrepancy of large and small diameter saw blade when rocks were sawed by combination saw, and abrasion loss of segment adopted to small diameter saw blade was significantly higher than that of large-diameter saw blade. Diameter variation of saw blade in combination saw caused the different wear mechanism of diamond in segment, pulled-out and macro-fractured crystals were dominant in small-diameter saw blade, then the proportion of whole particles increased in segment used to the saw blade of large diameter. Particle protrusion height was related to the diameter in the combination saw. The high protrusion height of particles existed in the large-diameter saw blade.

Effect of ion dose ratio on multilevel energy smoothing model of gas cluster

In this study, two kinds of gas cluster ion beam energy modes with different ion dose ratios are proposed to improve the traumatic surface of n-Si (100) single crystal. In mode1, low-dose high-energy clusters and high-dose low-energy clusters are used, while in mode2, high-dose high-energy clusters and low-dose low-energy clusters are used. The results show that the flattening effect of mode 1 is better than that of mode 2, and the root mean square roughness of mode 1 and mode 2 are 0.62 nm and 1.02 nm, respectively. This is because in multi-level energy mode 2, high-dose high-energy clusters are used to bombard the target surface in the early stage, so that more ion damages will be left after high-energy cluster bombardment. In the later stage, low-dose low-energy clusters can only remove part of the ion damages, and the repair strength is not strong enough. In multi-level energy mode1, we first use low-dose high-energy clusters to bombard the surface of the target, so that the high-energy clusters can quickly remove the shape objects with high protrusion on the sample surface, and in the low-dose mode, it will not leave too many ion damages, which is conducive to the later repair. In the first stage of multi-level energy mode, high-dose low-energy clusters are used to bombard the target surface, which can not only reduce the ion loss, but also increase the time for low-energy clusters to repair ion damages, thereby yielding the optimal flattening effect. In order to verify the relationship among the damage removal, ion damage degree and cluster energy, a single energy cluster bombardment experiment with mechanical damage is carried out before the multi-level energy mode modification is studied. The results show that when the cluster ions are accelerated at 15 kV high voltage, the scratch removal efficiency is highest, and the surface scratch is very shallow, but the decease of roughness is not obvious; when the cluster ions are accelerated at 8 kV and 5 kV, the sample surface becomes fine and the remaining ion damages are least. At the same time, a comparison of the target bombarded by the multi-level energy mode 1 clusters with that by the single energy clusters shows that the multi-level energy mode can obtain a smoother target surface than the single 15 keV high-energy cluster treatment; the multi-level energy mode can better remove scratches and other wounds than the single 5 keV low-energy cluster treatment. Multistage energy mode 1 integrates the advantages of high and low energy clusters, thereby achieving the best flattening effect.

Mechanical and electrolytic hybrid grinding of metal ceramic composites using coarse diamond grinding wheel

The application and development of metal ceramic composites have been restricting due to its low grinding efficiency and ground quality. In this paper, the hybrid machining technology combined mechanical with electrolytic grinding based on dressed coarse diamond grinding wheel is proposed to perform efficient and precise grinding of metal ceramic composites. First, the dry electrical discharge dressing technology was used to dress coarse diamond grinding wheel to obtain high grain protrusion and sharp micro-grain cutting edges. Next, the mechanical and electrolytic hybrid grinding process using dressed coarse diamond wheel was developed to grind metal ceramic. Finally, the effects of different process parameters on ground surface topographies and surface roughness were investigated. It is shown that the proposed hybrid grinding method was feasible and can effectively improve the ground surface quality. The experimental results show that the optimal process parameters including the depth of cut, open-circuit voltage and impulse width were 5 μm, 20 V and 400 ns, respectively. Compared with traditional mechanical grinding, the ground surface roughness by the proposed hybrid machining method was improved by about 25%.

Grinding of alumina ceramic with microtextured brazed diamond end grinding wheels

Brazed monolayer diamond grinding wheels have advantages of a high abrasive bonding strength, high protrusion, and a large chip disposal space. However, it is difficult to prepare ordered and fine-grained brazed diamond grinding wheels. This study presents a new method for grain-arranged, brazed diamond grinding wheels with microtextures with similar performance to ordered and fine-grained brazed diamond grinding wheels. First, coarse diamond grains (18/20 mesh) were orderly brazed to fabricate the end grinding wheels. Next, a series of microtextures were ablated on the diamond grains using a pulsed laser, and two types of textured end grinding wheels—TG-G (ablated microgrooves only) and TG-GH (ablated microgrooves and microholes)—were prepared. Then, an experiment involving the grinding of alumina ceramics was performed, and the grinding characteristics and grinding mechanism were analyzed. The results indicated that compared with untextured diamond end grinding wheels (TG), the textured diamond grinding wheels (TG-G and TG-GH) significantly reduced the grinding force and the roughness of the machined surface. The local stress concentration at the microtextures promoted the formation of microcracks in the diamond grains of TG-G and TG-GH, and the self-sharpness of the grinding wheel was significantly improved. The brittle fracture mode of ceramic materials in grinding included intergranular fracture and transgranular fracture. Ironing pressure action was a key material-removal mechanism. It had an important influence on the cutting force and plasticity characteristics of the TG machined surface. For the surfaces processed by TG-G and TG-GH, the effect of ironing was weakened, while shearing played a more important role. The TG-GH grinding wheel ablated with microgrooves and microholes was superior to the TG-G grinding wheel ablated with only microgrooves, with regard to the grinding force, roughness, and self-sharpening.

Abrasive Disc Performance in Dry-Cutting of Medium-Carbon Steel

Abrasive-cutting processes are widely used to obtain semi-finished products from metal bars, slabs, or tubes. Thus, the abrasive cutting-off process is applied when requiring precision cutting and productivity at a moderate price. Cut-off tools are discs composed of small abrasive particles embedded in a bonding material, called the binder. This work aims to compare the cutting performance of discs with different composition, in dry cutting of steel bars. To do that, disc wear was measured and disc final topography was digitalized in order to determine both disc surface wear patterns and if the abrasive particles bonding into the binder matrix was affected. In addition, X-Ray inspection gave information about the abrasive grit-binder bonding. Therefore, the method here presented allows identifying discs with a superior abrasive-cutting capability, by combining profilometry and tomography to define micrometrical aspects, grit size, and binder matrix structure. Results led to the conclusion that discs with high grit size and protrusion, high grit retention by bond material, and closer mesh of fiberglass matrix binder were the optimal solution.

Electrical and Mechanical Analysis of Different TSV Geometries

Through-silicon via (TSV) is an important component for implementing 3-D packages and 3-D integrated circuits as the TSV technology allows stacked silicon chips to interconnect through direct contact to help facilitate high-speed signal processing. By facilitating the stacking of silicon chips, the TSV technology also helps to meet the increasing demand for high density and high performance miniaturized electronic products. Our review of the literature shows that very few studies have reported on the impact of TSV bump geometry on the electrical and mechanical characteristics of the TSV. This paper reports on the investigation of different TSV geometries with the focus on identifying the ideal shapes for improved electrical signal transmission as well as for improved mechanical reliability. The cylindrical, quadrangular (square), elliptical, and triangular shapes were investigated in our study and our results showed that the quadrangular shape had the best electrical performance due to good characteristic impedance. Our results also showed that the quadrangular and cylindrical shapes provided improved mechanical reliability as these two shapes lead to high Cu protrusion of TSV after the annealing process.

Efficient and Precise Grinding of Sapphire Glass Based on Dry Electrical Discharge Dressed Coarse Diamond Grinding Wheel.

In this paper, in view of low grinding efficiency and poor ground surface quality of sapphire glass, the coarse diamond grinding wheel dressed by dry impulse electrical discharge was proposed to perform efficient and precise grinding machining of sapphire glass. The dry electrical discharge dressing technology was employed to obtain high grain protrusion and sharp micro-grain cutting edges. The influences of grinding process parameters such as wheel speed, depth of cut and feed speed on the ground surface quality, grinding force and grinding force ratio on sapphire glass were investigated, and the relationship between grinding force and ground surface quality was also revealed. The experimental results show that the grain protrusion height on the surface of a coarse diamond grinding wheel dressed by dry electrical discharge can reach 168.5 µm. The minimum line roughness Ra and surface roughness Sa of ground sapphire glass surface were 0.194 µm and 0.736 µm, respectively. In order to achieve highly efficient ground quality of sapphire glass, the depth of cut was controlled within 7 µm, and the wheel speed and feed speed were 3000–5000 r/min and 10–20 mm/min, respectively. The influences of feed speed and wheel speed on grinding force ratio were more significant, but the influence of depth of cut was little.

Material removal and surface generation mechanisms in diamond wire sawing of silicon crystal

Silicon crystal is usually first cut into wafers in the applications of electronic devices and photovoltaic solar cells. At present, fixed abrasive wire sawing technology has been widely used in slicing. The mechanism of material removal and surface generation during wire sawing is the key basic problem to study the surface quality of sliced wafers, which is important to realize high-precision slicing. This paper presents theoretical analysis on the relationship between the average cutting depth of abrasives distributing in different positions along the wire circumferential surface and the process parameters. The wire sawing experiments of single crystal silicon were carried out, then the morphologies of sawn surface and swarf were observed, the surface roughness was measured and analyzed, the material removal and surface generation mechanism of single crystal silicon cut by electroplated diamond sawing wire were addressed. Research results show that there is an approximate non-linear increasing relationship between the average cutting depth of the abrasives and the ratio of the workpiece feed speed to the wire speed, and the abrasives cutting depth and surface roughness of sliced wafers increases with the increasing of ratio value. It is difficult to obtain the sliced surface in a fully ductile mode of material removal in the actual wire sawing process because there are always a small amount of abrasives with high protrusion on the wire surface whose cutting depths are greater than the critical ductile regime cutting depth, but adopting a low ratio can make the generation of the sliced wafer surface in near-ductile or local-ductile material removal mode which can produce high quality wafer surface. This research is expected to be useful in optimizing the combination of process parameters in fixed abrasive diamond wire saw precision slicing of silicon wafers.

Impact of Imprint Pressure on Residual Layer Thickness in UV Nanoimprint Lithography

Ultraviolet nanoimprint lithography (UV-NIL) is an important micro/nano fabrication approach. UV-NIL has the advantage of high solution, high throughput and low cost. However, some inner resist flow mechanism is not completely understood by experimental methods. This contribution used the simulation method based on contact mechanics to analyze the impact of imprint pressure on residual layer thickness (RLT). Seven different pressure, from 0.1 MPa to 0.7 MPa, was applied to imprint the same stamp containing grating patterns with various protrusion density. It was found that RLT is not uniform and the areas with high protrusion density has much higher RLT. The average RLT decreases with imprint time and tends to be stable when the imprint process is completed. Both the maximum and minimum RLT decreases with the increase of imprint pressure. These findings can help engineers to design proper stamp pattern distribution and process parameters. Introduction

Optimization of Micropencil Grinding Tools Via Electrical Discharge Machining

Micropencil grinding tools (MPGTs) are micromachining tools that use superabrasives like diamond and cubic boron nitride (cBN) grits to manufacture complex microstructures in a broad range of hard and brittle materials. MPGTs suffer from a rather low tool life, when compared to other more established microprocessing methods. It was documented that when used on hardened steel workpieces, MPGTs suffer from a large amount of adhesions, mostly located at the pivot point of the tool. These adhesions lead to the clogging of the abrasive layer and ultimately in tool failure. Another problem this machining process suffers from is the formation of substructures (smaller channels inside the microchannels). The pivot is usually less prone to abrasive wear, has higher protrusion, and is therefore responsible for the deepest substructures. These substructures can easily take up half the depth of cut, obstructing the function of machined microchannels—it is one of the major flaws of this micromachining process. A micro-electrical discharge machining method (μEDM) can solve these issues by manufacturing a cavity at the pivot of these tools. A novel method that uses measurement probes to position the substrate above the μEDM electrode is implemented and a parameter study to determine the cavity manufacturing parameters is conducted for substrates with diameters < 40 μm. The goal is to demonstrate the first ever complete and reliable manufacturing process for MPGTs with a cavity and to demonstrate the advantages they provide in a machining process when compared to regular MPGTs.

Friction Behavior of Human Skin Rubbing against Different Textured Polymeric Materials Obtained by a 3D Printing Microfabrication Technique

Understanding friction behavior of human skin is indispensable in order to optimize surfaces and materials in contact with the skin. The coefficient of friction (COF) for different materials contacting against the skin is mainly influenced by the nature of the materials, mechanical contact parameters, and physiological skin conditions. The aim of the present research work was to study the grip effect of two different polymeric materials by producing different textured patterns using a 3D printing microfabrication technique and a replication technique. It was found that under the same contact conditions, a difference in the friction amplitude exists between the two different polymeric materials and that positive texturing, which consists of high relief or protrusions, showed higher COFs than negative texturing, consisting of low relief, holes, or dimples, which showed a decrease in friction as the textured pattern area density increased.

Sound diffusion design process using scale models of a concert hall and acoustic parameters

This study proposed a design process for diffusion walls of the Art Center Incheon concert hall by using scale models and verified the sound diffusion performance in comparison with acoustic parameters. Locations of diffusers and main diffusing surfaces were determined in a 1:50 scale model, and the heights of diffusers in the stage were set and diffusion rates were evaluated according to occupancy density in a 1:25 scale model. A 1:10 scale model enabled the real acoustic characteristics of the concert hall to be evaluated. This model was used to measure scattering/diffusion coefficients of diffusers in each part and to design the finishing shapes of walls. Horizontal diffusers with the highest protrusion were installed on the lateral walls near the stage in order to orientate scattered reflections. Impulse responses were used to investigate acoustic parameters like RT, EDT, G, and C80, and the number of peak reflection (Np) was calculated to compare diffusion performance. It turned out that, when the amount of diffusion changed, the value of Np increased but the values of RT, EDT, and G and the corresponding relative standard deviation (RSD) decreased. The ratio of 1:25 or higher scale models were efficient in designing the diffusion surfaces of the concert hall. The effectiveness of scale models was verified as the directions, locations, protrusion heights, and areas of diffusers were determined.