Exposed Area Ratio Research Articles

Research on Categorizing and Deriving Proportions of Hanoks for Planning and Designing Hanok Architecture

A Hanok is a representative wooden structure in Korea and is recognized for its environmentally friendly architecture. Since the 2010s, the demand for Hanoks has increased significantly, but new Hanoks tend to be built with only numerical changes to existing plans or only imitate the shape. This is due to the fact that architectural designers do not have systematic training in Hanoks, so they rely on carpenters with extensive experience in Hanok construction. As designers reconfigure Hanok’s floor plan space using existing drawings to accommodate modernization, the building’s form changes as spatial reduction and expansion occur. This change in form creates problems with the proportions of the elements that make up a Hanok, such as the roof being smaller than the body or the building being taller than the scale of the floor plan. A more significant issue is the lack of recognition of the proportion problem. Therefore, this study has a direct role in the systematic design and construction of Hanoks by deriving objective proportions of Hanoks. To increase the objectivity of the data, numerical data of floor plans, cross-sections, and front elevations of national heritage Hanoks with well-preserved traditional shapes were extracted and analyzed for patterns. Subsequently, similar forms were categorized, and ultimately, the plan, section, and elevation proportions were quantified. The results indicated that the plan was characterized by spatial expansion in the X-axis direction more than the Y-axis while maintaining rectangular proportions. The cross-sectional structure showed a change in height depending on the width of the plan, and it was found that the larger the width of the plan, the lower the height ratio of the cross-section. Of particular interest was the analysis of the ratio of exposed area in the elevation, divided into three areas: roof, Gongpo, and the frame, and the interaction between the roof and Gongpo was confirmed within 63.7% of the total exposed area ratio. This result suggests that the proportion of Hanoks exists despite the different scales, times, and locations of Hanoks. This study can serve as a reference for designers in the process of verifying and modifying design drawings, and it is significant in providing a method and direction for building a new dataset for Hanok design.

Experimental study on combustion and flame spread characteristics in horizontal arrays of discrete fuels

Abstract The combustion and flame spread behaviors of discrete fuels often depend on the distribution of the fuel arrays, including the fuel bed width and the spacing of the fuel arrays. In this study, scenarios with six different numbers of columns (n, 1–11 with an interval of 2) and nine different spacings (S, 1–9 mm) were designed. By varying n and S, 54 groups of experimental scenarios over thermally thick birch rod arrays were studied to determine the effects of fuel bed width and spacing. The experimental results showed that the critical spacing for multi-column arrays was larger than that for single-column arrays. Moreover, flame extinction was found when n > 1 and S = 1 mm . The value of S had a limited influence on the mass loss rate when S > 2 mm , but restrained the mass loss rate when S ≤ 2 mm . A piecewise correlation between a newly defined dimensionless mass loss rate and the exposed area ratio was proposed. Moreover, a prediction model of the mass loss rate was developed, which agreed reasonably well with the experimental data. With increasing spacing, the flame height showed three stages: increasing, relatively stable, and decreasing, which were dominated by the balance between air entrainment and radiant heat feedback. The three processes were further described by a piecewise correlation between the dimensionless flame height and fuel bed width. Based on the assumption of a constant incident heat flux, a prediction model of the global flame spread rate was built, which presented better predicted results than the previous models. In addition, it was found that the newly defined dimensionless global flame spread rate linearly increased with increasing porosity.

Initial stage of localized corrosion in artificial pits formed with photon rupture on Zn–5 mass% Al alloy-coated steel

The photon rupture method, by which oxide film and metal are removed by focused pulsed Nd–YAG laser beam irradiation, was applied to form artificial micro-pits in Zn–5 mass% Al alloy-coated steel. The zinc alloy-coated layer was removed by pulsed laser irradiation treatment for about one second in a neutral buffer solution with NaCl. The rest potential transient with the laser treatment was measured. In the early stage of the laser treatment the rest potential of zinc alloy-coated steel changed to the negative direction immediately after every irradiation of a laser pulse and then returned to the previous value. However, after the steel substrate was exposed to the solution, the rest potential moved to the positive direction immediately after every irradiation of a laser pulse and then returned to the previous value. The amplitude and duration of the potential change after the laser irradiation increased with repetition of laser irradiation, related to the pit depth and the exposed area ratio of coated layer/steel substrate. The rest potential fluctuation difference can be explained by galvanic reaction change in the artificial pit formed by laser irradiation on the Zn alloy-coated steel.

Initial Stage of Localized Corrosion in Artificial Pits Formed with Photon Rupture on 55mass%Al–Zn Coated Steels

The photon rupture method, whose oxide film and metal are removed by focused pulsed Nd-YAG laser beam irradiation was applied to form artificial micro pits in 55mass% aluminum-zinc coated steels. The 15 μm coated layer was removed by 2 s of continuous laser irradiation in this experiment. The rest potential transients were measured during the laser irradiation. While the coated layer covered the steel substrate, the rest potential change in the negative direction just after the starts of the laser irradiation and then returned to the previous value. However, after the steel substrate was exposed to solution, the rest potential moved in the positive direction immediately after the discontinuation of the laser irradiation and then also returned to the previous value. The amplitude and duration of the potential changes after the laser irradiation increased with longer irradiation, related to the pit depth and exposed area ratio of coated layer/steel substrate. These rest potential fluctuation differences can be explained by galvanic reaction changes in the artificial pit formed on the coated steel during irradiation.

Exposed area ratio dependent etching in a submicron self-aligned contact etching

The mechanism of selective SiO2 etching over Si3N4 has been studied with the simulation of a ladder-type surface profile and specially designed experiments in a submicron self-aligned contact (SAC) etching process. The ladder-type profile, which is the boundary of broken shoulder Si3N4, is normally observed during a highly selective SAC etching. The structure of two adjacent SiO2 and Si3N4 lines is prepared and etched in a surface wave plasma (SWP) etching system in order to investigate the effect of fluorocarbon polymer deposition on the selectivity and the ladder profile. This designed experiment shows that the removal (adding) of fluorocarbon polymer in a SAC etching directly decreases (increases) the selectivity and changes the ladder-type profile. A new surface reaction model for SiO2 etching has been developed to simulate the behavior of polymer and the ion enhanced dry etching. The simulation reasonably recovers the ladder-type profiles with the effects of polymer deposition and SiO2 etch byproducts, which are thought to be the main control factors of surface reactions in a submicron SAC etching. From the results of simulation and experiment, it is suggested that the structure for SAC process has to be optimized to maximize the selectivity of shoulder Si3N4 and photoresist at the same time.

End-point Detection of Reactive Ion Etching by Plasma Impedance Monitoring

For the practical application of end-point detection of etching using plasma-impedance monitoring, the factors determining the impedance were clarified using an electric circuit model of a reaction chamber. In the model, plasma is approximated by a conductor, and the floating capacitance and wafer of a powered electrode, as well as the powered-electrode sheath (the sheath formed between the plasma and powered electrode), are approximated by capacitors. Calculated values obtained using the model agree well with measured values obtained by an impedance monitor installed between the powered electrode and the matching network. Based on this result, it was inferred that the impedance depends on the powered-electrode sheath-voltage and electron density, as well as on the floating capacitance and area of the powered electrode, the dielectric constant and thickness of the wafer, and the electron temperature. Next, the end-point detection method of etching by impedance monitoring was applied to reactive ion etching of SiO2 films, and the following finding was confirmed: the change in the impedance significantly depends on the RF power and the exposed area ratio (the ratio of etched area to wafer area) on the wafer. In addition, the feasibility of detecting the point of change of the exposed area ratio on the wafer, where the area size varies during etching, by detecting microchanges in the impedance, was demonstrated. As a result, the possibility of highly accurate end-point detection of etching by impedance monitoring was confirmed.

Effect of Re-sticking Acid on Resist Profile.

We investigated resist profile change caused by re-sticking acid from exposed area during PEB. Using high activation energy type chemically amplified positive resist, the profile changed from T-top to rounded profile with increasing Exposed Area Ratio (EAR). We thought that this profile change was caused by acid evaporation from exposed area and its re-sticking on patterned area. To estimate the effect of re-sticking acid, we performed resist sandwich tests and observed resist profile change caused by re-sticking acid. The results thereby obtained support the model we propose.To reduce the effect of re-sticking acid, we tried to use an OverCoat Layer (OCL). The effect of OCL was certified to be useful during PEB not during exposure.

The development of repairable Au-Al solid phase diffusion flip-chip bonding

The authors have developed a new repairable chip-on-glass (COG) bonding technique for liquid crystal display (LCD) panels. Gold (Au) bumps on an LSI chip were bonded directly to aluminum (Al) electrodes on a glass substrate by formation of Al-Au intermetallic compounds in the diffusion layer. The developed repairable bonding technique consists a of two-level bonding process. First, the chip was bonded at 250/spl deg/C. Partial interconnection could be obtained at the local contact portions between the Au bump and the Al electrode. If the electrical connection failed, the bonded chip was removed. There was a distribution of the area formed Al-Au intermetallic compounds at local contact portions for 250/spl deg/C bonding. Some areas formed Al-Au intermetallic compounds of the Al electrode were sometimes removed with the chip removal, and an underlying metal layer was locally exposed at the remained surface. Then, a new chip was bonded on the same Al electrodes under the same conditions at 250/spl deg/C. After obtaining the electrical connection, the second bonding was done at 350/spl deg/C. An AlAu4 intermetallic formation was obtained by this bonding in the diffusion layer. Reliability tests of second bonded samples were carried out and the contact resistance between the Au bumps and the Al electrodes was measured by the four-probe resistance measurement. In the case that the exposed area ratio of the underlying metal layer was less than 30% of bonding area for each Al electrode, the stable electrical connection has been kept for a high temperature storage test and a thermal shock test. It was confirmed that a stable electrical connection had been obtained by the proposed repairable bonding process.

The protection of mild steel by zinc-rich paint in flowing aerated 0.5 M NaCl solution—II. The effect of exposed area ratio

Experiments were performed in aerated 0.5 M NaCl solution over a range of selected Re numbers, using electrode couples of painted steel to bare steel at varying surface ratios. Results showed that, provided the painted to bare steel ratio was high flow, effects were not harmful. The bare steel was protected by a thin grey film of protective zinc hydroxide. Areas containing iron corrosion products were afforded temporary protection by a non-protective type of bulky white corrosion product, providing the steel was being subjected to cathodic protection. Once this was lost rusting of the underlying steel restarted at these points with iron corrosion products breaking through this overlying non-protective film.

The protection of mild steel by zinc-rich paint in flowing aerated 0.5 M NaCl solutions.—I. The effect of zinc particle size

An accelerated testing procedure was used to determine the effect of average zinc dust particle size on the electrochemical behaviour of a zinc-rich chlorinated rubber primer applied to mild steel. Tests with a painted surface to exposed area ratio of 11.6 to one in flowing aerated 0.5M NaCl solution showed that a particle size of 2.5 μm provided the best protection over the flow range investigated.