• Journal of the Korean Institute of Gas
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• v.25 no.6
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• pp.53-65
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• 2021

While the hydrogen refueling station is rapidly expanded and installed, the safety inspection of the hydrogen pressure vessel in the station should be very important. Of these, according to ASME, hydrogen embrittlement tests must be performed for hydrogen vessel that store hydrogen above a certain pressure. The main test method for hydrogen embrittlement inspection is to carry out fracture tests and fatigue fracture tests in a high pressure hydrogen atmosphere, which allows the durability limit of the pressure vessel to be measured and the endurable limit to be determined in the hydrogen atmosphere. In detail, the critical crack depth can be calculated by the stress intensity factor(K), and the service life can be determined by da/dN (fatigue growth rate). API579-1/ ASME FFS-1 part 9 exemplifies the calculation method according to the mode of crack-like flaws, but for various shapes such as plates and cylinders, there are about 55 modes according to the shape and location of the crack. Due to the fairly complex formula, it is not easily accessible. In this study, we will show you how to calculate fracture mechanics numerically via Excel and VBA. In addition, this was applied to analyze the effects of the thickness and inner diameter of the pressure vessel on the service life.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.29 no.6
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• pp.335-349
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• 2017

Submerged breakwaters installed under the water surface are a representative coastal structure to prevent coastal erosion, and various types of submerged breakwaters have been proposed and discussed so far. Generally, submerged breakwaters make the complex wave fields due to abrupt change in water depth at the crown of the breakwater. In this study, wave heights and mean water level formed around a breakwater are examined numerically for three-dimensional permeable submerged breakwaters. OLAFOAM, CFD open source code, is applied in the numerical analysis, and the comparisons are made with available experimental results on the permeable upright wall and the impermeable submerged breakwater to verify its applicability to the three-dimensional numerical analysis. Based on the applicability of OLAFOAM numerical code, the wave height and mean water level distribution formed around the permeable submerged breakwaters are investigated under the formation condition of salient. The numerical results show that as the gap width between breakwaters decreases, the wave height in the center of the gap increases, while it decreases behind the gap, and the installing position of the breakwater from the shoreline has little influence on the change of the wave height. Furthermore, it is found that the decrease of the mean water level near the gap between breakwaters increases with decreasing of the gap width.

• Journal of the Korean Society of Marine Environment & Safety
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• v.25 no.7
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• pp.936-944
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• 2019

Submarines, which have been called an invisible force, are strategic underwater weapon systems that perform missions such as anti-surface warfare, anti-submarine warfare, and high payoff target strikes with the advantage of underwater covertness. A submarine should be able to withstand the hydrostatic pressure of the deep sea. In this respect, the submarine pressure hull, as the main structural system to resist the external pressure corresponding to the submerged depth, should ensure the survivability from hazards and threats such as leakage, fires, shock, explosion, etc. To do this, the initial scantling of the submarine pressure hull must be calculated appropriately in the concept design phase. The shape of the aft transition ring varies according to its connection with the submarine aft end conical structure, pressure hull cylindrical part, and non-pressure hull of the submarine; the design of the aft transition ring should not only take into account stress flow and connectivity but also the cost increase due to the increased man-hours of its complex geometry. Therefore, trade-off studies based on the four different shapes of the aft transition ring are carried out considering both the review of the structural strength through nonlinear finite element analysis (FEA) and economic feasibility by reviewing the estimations of the manufacturing working days and material costs. Finally, the most rational structural aft transition ring shape for a submarine amongst four reviewed types was proposed.

• Journal of Korea Water Resources Association
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• v.55 no.5
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• pp.345-356
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• 2022

A severe flooding occured at a small urban catchment in Daejeon-si South Korea on July 30, 2020 causing significant loss of property (inundated 78 vehicles and two apartments) and life (one casualty and 56 victims). In this study, a retrospective analysis of the inundation event was implemented using a physically-based urban flood model, H12 with high-resolution data. H12 is an integrated 1-dimensional sewer network and 2-dimensional surface flow model supported by hybrid parallel techniques to efficiently deal with high-resolution data. In addition, we evaluated the impact of the flooding barriers which were installed after the flood disaster. As a result, it was found that the inundation was affected by a combination of multiple components including the shape of the basin, the low terrain of the inundation area located in the downstream part of the basin, and lack of pipe capacity to drain discharge from the upstream during heavy rain. The impact of the flooding barriers was analyzed by modeling with and without barriers on the high-resolution terrain input data. It was evaluated that the flood barriers effectively lower the water depth in the apartment complex. This study demonstrates capability of high-resolution physically-based urban modeling to quantitatively assess the past inundation event and the impact of the reduction measures.

• Journal of the Korea Fashion and Costume Design Association
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• v.19 no.4
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• pp.93-104
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• 2017

This study is a basic study to develop shoe last design technology to enhance and revitalize the competitiveness of the handmade shoes. In-depth interviews were conducted with four manufacturers in Seongsu-dong to identify the production status and design technology of shoe lasts. The result of the research is as follows. Firstly, shoe lasts for adults are produced at intervals of 5mm between 245mm-285mm for men's shoes, and between 220-260mm for women's shoes. The production rate of women's shoes was high in the order of general type, boot type, and sandal type while men's shoes mainly produce general type. Secondly, the master last size and ball girth rating for men's and women's shoes were analyzed to EE-EEE grade at 260mm and D grade at 235mm. The length of the master last for men's shoes is 276-290mm, the heel width is 60-65mm, the ball width is 88-90mm, the ball girth is 250mm, and the waist girth is 248mm. The length of the master shoe last for women's shoes is 236-245 mm, the heel width is 50-55mm, the ball width is 78-80mm, the ball girth is 211~213mm, and the waist girth is 213~215mm. Thirdly, the last grading deviation is 5mm in length, the heel width is 0.5mm, the ball girth is 3.5mm, and the ball with is 1.2mm. The ball girth dimensions of Oxford type, slip-on type, and sneakers type are made at 250mm, 248mm, and 245mm for men's shoes. For women's shoes, the ball girth dimensions of pump type, loafer & boot type, and sandal type are made at 211~213mm, 214~215mm, and 211mm. Fourthly, t+he construction of the automation system is insufficient and almost completely depends on manual production.

• Journal of the Economic Geographical Society of Korea
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• v.17 no.2
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• pp.231-248
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• 2014

The role of the foreign direct investment is very crucial for the regional economic growth nowadays. The inward FDI in Korea has been increased since the Act of foreigner investment promotion in 1998. The municipal and national government have designated the special industrial zones and supported the diverse incentives for the foreign investment companies. The service sector had a large share of inward FDI. However, manufacturing sector overtook the service sector as the largest FDI in 2009. This study focuses on the greenfield manufacturing FDI, which was established from 1999 to 2012 in Korea. In order to find out the impacts of low-priced industrial electricity and loose environmental regulations on choosing Korea, this paper did in-depth interviews with MOTIE, Korea industrial complex, Korea Trade-Investment Promotion Agency, some FDI companies. Investment incentives such as low price of domestic industrial electricity strongly affect why manufacturing FDI companies choose Korea to invest. The Korean government has also acknowledges that low-price policy can internationally compete to attract FDI. There is a possibility that FDI energy-guzzling industrial companies may choose for Korea to use the low-priced electricity, raising the issue of supply-demand of electricity of Korea in the future.

• Fashion & Textile Research Journal
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• v.14 no.2
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• pp.193-202
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• 2012

With entering the 21st century, modern people's dark inside and panic are emerging as the talking point on the theater stage. Even in the field of stage costume, the necessity of a research is being demanded through analyzing on psychological anguish and structure of characters. Accordingly, this study aims to allow the stage costume design to be expressed a human being's Doppelg$\ddot{a}$nger Image, which was elicited through analyzing a work of the play titled Le Grand C$\acute{e}$r$\acute{e}$monial by a playwriter Fernando Arrabal, who draws the conflictory and contradictory duplicity, which positions in a human being's deep inside by having chaos as catalyst. A research subject is 'Le Grand C$\acute{e}$r$\acute{e}$monial,' which was staged as the winter performance in commemoration of the 50th anniversary for the foundation of Dept. of Theater, Chung-Ang Univ. in November 2009. Psychology of characters in a play, which varies dimensionally, could be delivered, as nonverbal element called costume, by applying costume design of Cavanoza, Syl, Nice to Doppelg$\ddot{a}$nger Image such as Innocence vs Cruelty, Purity vs Superficiality and Restraint vs Freedom, which were elicited through analyzing characters. Through this study, the costume, which was expressed by visualizing a human being's Doppelg$\ddot{a}$nger Image, could be known to function as important dramatic factor of allowing character's psychology to be understood through costume as well as functioning as visual and sensible language, which is important for communication with the audience. A research on costume design, which reflects a character's complex inside, is expected to be likely continued through in-depth analysis on a playwriter's intention and on the appearing characters at the current point of time when an active research is being performed on stage costume in the wake of this study.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.23 no.5
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• pp.393-400
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• 2011

The mass transport is very complicated at the area which has the macro tide and complex geometry such as Gyeonggi bay. Especially, the long period current has a strong influence on the estuarine ecosystem and the long-term distribution of substances. The long period current is caused by several external forcing, whose unique characteristic varies spatially and temporally. The variation characteristics of long period current is analysed and its generation mechanism is studied. The tidal nonlinear constituents such as overtide and compound tide are generated due to nonlinear interaction and it causes mean sea level setup. The tidal wave propagating up into estuary is transformed rapidly by decrease of cross-sectional area and depth. Therefore the mean sea level is getting rise toward upriver. The high and low tide level is similar between down-river(Incheon) and up-river(Ganghwa) during neap tide when the tidal deformation is decreased. The tidal phase difference between two tidal stations causes a periodic fluctuation of sea level difference. The low water level of Ganghwa station during spring tide does not descend under EL(-)2.5 m, but the low water level of Incheon fall down under EL(-)4.0 m. The variation of tidal range and its sea level are increased during spring tide. It is found that the long period current $M_{sf}$ is quite similar to that of sea level difference between the two tidal stations. It means that the sea surface inclination caused by the spatial difference of tidal deformation is important forcing for the generation of long period current.

• Journal of the Korean Society for Marine Environment & Energy
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• v.17 no.3
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• pp.224-235
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• 2014

Changes in the interactions among incident ocean water waves, coastal debris (marine debris), and the back vegetation zone line on a natural sandy beach on the island of Jinu-do in the Nakdong river estuary were investigated. The study involved a cross-sectional field survey of the beach, numerical modeling of incident ocean water waves, field observations of the distribution of coastal debris, and vegetation zone line tracking using GPS. The conclusions of this study can be summarized as follows: (1) The ground level of the swash zone (sandy beach) on Jinu-do is rising, and the vegetation zone line, which is the boundary of the coastal sand dunes, shows a tendency to move forward toward the open sea. The vegetation zone line is developing particularly strongly in the offshore direction in areas where the ground level is elevated by more than 1.5 m. (2) The spatial distributions of incident waves differed due to variations in the water depth at the front of the beach, and the wave run-up in the swash zone also displayed complex spatial variations. With a large wave run-up, coastal debris may reach the vegetation zone line, but if the run-up is smaller, coastal debris is more likely to deposit in the form of an independent island on the beach. The deposited coastal debris can then become a factor determining which vegetation zone line advances or retreats. Finally, based on the results of this investigation, a schematic concept of the mechanisms of interaction between the coastal debris and the coastal vegetation zone line due to wave action was derived.

• Journal of the Korean Chemical Society
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• v.61 no.6
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• pp.378-387
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• 2017

In this study, we analyzed the causes of decrease in the number of students taking Chemistry ? in the College Scholastics Ability Test (CSAT) by analyzing the adequacy of the Chemistry I question in the CSAT and the recognition survey of students and teachers about the Chemistry I choice. We analyzed some questions in Chemistry I of the CSAT from the year 2014 to 2016. The questions were analyzed to determine whether they were appropriate to the curriculum content, achievement standard, and achievement level. The target of the survey for perception was 452 senior high school students and 68 science teachers. The result of the study showed that the questions in Chemistry I are somewhat difficult compared to the depth and achievement level required by the curriculum, and it also requires mathematical thinking ability. Students recognized the mathematical thinking and complex mathematical skills are needed to solve problems in Chemistry I. Teachers also thought that the choice of Chemistry I is unfavorable in aspect of meeting the minimum academic ability standard, and accordingly, they did not actively recommend students to take Chemistry I. Moreover, most of the teachers recognized that it is necessary to improve the direction of writing questions for Chemistry I. Therefore, setting questions that can be solved using chemical knowledge, not mathematical ability need to be addressed.