• Journal of the Korean Institute of Gas
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• v.12 no.2
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• pp.69-76
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• 2008

Three failure cases of CNG composite vessels were reported since after January 2005. The 1st and 2nd accidents were indebted to vessel defect and installation mistake. The 3rd was caused by gas leak at pipe connections. In this paper various aspects were studied based on information of the three failure analysis, which must be improved for better safety of the CNG bus system. Overpressure region caused by vessel explosion was theoretically predicted and also assessed by PHAST program. Explosion of 120 l vessel under 20 MPa is equivalent to 1.2 kg TNT explosion. The predicted value by PHAST was more serious than theoretical one. However, actual consequence of explosion was much less than both of the predicted consequences. Since the CNG vessel was designed by the performance based design methodology, it is difficult to verify whether the required process and tests were properly conducted or not after production. If material toughness is not enough, the vessel should be weak in brittle fracture at early in the morning of winter season since the metal temperature can be lower than the transition temperature. If autofrettage pressure is not correct, fatigue failure due to tensile stress during repeated charging is possible. One positive aspect is that fire did not ocurred after vessel failure. This may be indebted to fast diffusion of natural gas which hindered starting fire.

• International Journal of Highway Engineering
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• v.12 no.4
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• pp.17-28
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• 2010

A climbing lane is installed to separate low-speed traffic from high-speed traffic if drastic traffic capacity reduction is expected due to a large number of vehicles that slow down in the upward section. Existing studies on climbing lanes have focused on the designation, location of starting and ending points, and installation method of climbing lane with regard to road design standards. However, in terms of traffic operation, it was known that the climbing lanes cause traffic congestion due to the increase of traffic volumes. In this regard, this study aims to establish traffic operational guidance as to how much effects temporary closure of climbing lanes can have on traffic improvement according to the volume-capacity ratio, grade, and composition of trucks. A test section of simulated climbing lane was selected in Nakdong JC bound for Masan(136.9K~133.3K, 3.6km, 3.7%) on Jungbunaeryuk expressway to conduct VISSIM analyses, microscopic traffic simulation based on such control variables as traffic volume(v/c), grade and the trucks ratio. As a result of the analyses, it has been found that v/c and the ratio of trucks are the key variables for efficient traffic management of climbing lanes in order to relieve traffic congestion via climbing lane. If ratio of trucks are more than 50% and when v/c would be 0.8, both climbing lane would be closed and non-operated regardless of grade and ratio of trucks when v/c is 1.0. With the increased traffic due to a five-day work week system, continued peak hours during the weekday, increased and various patterns of congestion on expressway, this study would be expected to contribute to facilitating researches on flexible operational standards for road facilities.

• Journal of the Korean Geographical Society
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• v.38 no.2
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• pp.275-291
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• 2003

It was essential to develop the DB-type teaching and teaming material for geography instruction using a method of ICT. The DB-type teaching and learning material was considered as a alternative in solving the problems of web-based geography instruction. Accordingly, in this study, the geography image DB program as developed, and based on this program the CD-ROM called GEO-DB, having the function of electronic dictionary of geography image for geography teaching and teaming was made. The GEO-DB was composed of 3,060 geography images collected by teachers and learners. The GEO-DB was made to be used simply by teachers and learners. Especially, the portfolio function was Included in the GEO-DB, and that was focused to the instructional system design of teacher and the self-directed teaming ability development of learner. Teachers and learners using this GEO-DB assessed that because the GEO-DB had the easiness of use, the speed of reference and the unlimitedness of extension, it could enlarge the possibility of using a method of In, and it could contribute to the development of geography teaming ability and the change of geography teaming attitude.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.06a
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• pp.328-328
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• 2007

Large area matrix-addressed image detectors are a recent technology for x-ray imaging with medical diagnostic and other applications. The imaging properties of x-ray pixel detectors depend on the quantum efficiency of x-rays, the generated signal of each x-ray photon and the distribution of the generated signal between pixels. In a phosphor coated detector the light signal is generated by electrons captured in the phosphor screen. In our study we simulated the lateral spread distributions for phosphor coupled detector by Monte Carlo simulations. Most simulations of such detectors simplify the setup by only taking the conversion layer into account neglecting behind. The Monte Carlo code MCNPX has been used to simulate the complete interaction and subsequent charge transport of x-ray radiation. This has allowed the analysis of charge sharing between pixel elements as an important limited factor of digital x-ray imaging system. The parameters are determined by lateral distribution of x-ray photons and x-ray induced electrons. The primary purpose of this study was to develop a design tool for the evaluation of geometry factor in the phosphor coupled optical imaging detector. In order to evaluate the spatial resolution for different phosphor material, phosphor geometry we have developed a simulation code. The developed code calculates the energy absorption and spatial distribution based on both the signal from the scintillating layer and the signal from direct detection of x-ray in the detector. We show that internal scattering contributes to the so-called spatial resolution drop of the image detector. Results from the simulation of spatial distribution in a phosphor pixel detector are presented. The spatial resolution can be increased by optimizing pixel size and phosphor thickness.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.11a
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• pp.502-502
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• 2007

A catenary system should be designed to have an uniform elasticity over a span in order to maintain the lowest possible loss of contact between a pantograph and a contact wire. A elasticity uniformity of a catenary can be regarded as a important design factor used for predicting the current collection performance for a catenary. There are a couple of formulas to calculate the degree of elasticity uniformity of a catenary according to the literature survey. The effectiveness of these formulas is reviewed by performing catenary elasticity and loss of contact analysis for various different configurations of catenary systems using a beam element based FEM program. The results reveals that these formulas are not suitable to predict the current collection performance for a catenary. Therefore, a new formula based on the standard deviation of the elasticity over a span is proposed in this study. The analysis results show that the new formula for an elasticity uniformity of a catenary is very effective in predicting the current collection performance for a catenary.

• International Journal of Highway Engineering
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• v.11 no.4
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• pp.143-152
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• 2009

The purpose of this study is to evaluate the freezing index and frost penetration depth. The freezing index and frost penetration depth were analyzed using air temperature and temperature profile of pavement system in Korea LTPP-SPS(Long Term Pavement Performance-Specific Pavement Study) site. The predicted frost penetration depth were then compared with the measured one from the LTPP sites. And the trend of annual freezing index was analyzed using the temperature data of meteorological stations located in the vicinity of Korea LTPP-SPS site. The result showed that the freezing index was rapidly decreased since 1987, and it was known that the use of freezing index determined from the past 30 years temperature data could cause the over estimates in the pavement thickness design. The temperature profile measured at 3 sections of LTPP-SPS sites showed that the temperature of subbase layer was above $0^{\circ}C$, even though anti-frost layers were found in these sections. Comparing the measured and calculated frost depth, the frost depth calculated from the subgrade frost penetration permissible method showed a similar trend with the measured frost depth.

• Journal of Korean Society of Rural Planning
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• v.26 no.4
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• pp.27-39
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• 2020

With the COVID-19 pandemic, the global economy has stagnated and our daily lives have changed. The rural economy is also experiencing damage, such as an average of 65% or more decrease in the number of visitors to rural experience resort villages due to the spread of COVID-19. In order to minimize the damage arising from the prolonged coronavirus, a hospitality system in response to changes in rural tourism behavior and consumer demand is needed to revitalize rural areas and maintain continuous economic independence. Therefore, this study attempted to find ways to utilize landscape resources such as education, culture, history, and ecology in order to complement the existing experience programs in connection with local resources and local environment. Wibong Village, which is the subject of the study, attempted to revitalize the village using the resources through the "Creative village creation" project in 2015. Due to poor management of historical resources, difficulty in operating experience programs, and response to changes in the natural environment, the rate of implementation of the project plan was very low. Currently, the demand for experience is also decreasing due to the COVID-19 effect, so it was judged that it was necessary to develop an experience village program suitable for the needs of experienced visitors by discovering additional local resources for the continuous operation of the experience village. In order to solve the problem of the use of landscape resources and the spatial composition of the study site, additional investigations of local resources were made, and an experience program course that could be operated by theme was proposed by configuring a space suitable for the use of landscape resources. By dividing the additionally investigated landscape resources into history, ecology, and region, an experiential course was created to separate the traffic lines, and the space composition for large-scale experienced visitors that had been previously operated was constructed in a form suitable for the post-corona era. In addition, at least two experiential tour courses that can be operated by period were proposed to maintain economic effects. Starting with this study, if further research on the creation and spatial composition of a rural experience village centered on the connection with the region, it will be used as research results that can be referenced in projects such as village creation, rural space planning, and living area analysis. It is expected that it will be able to effectively cope with the construction of a rural area suitable for the post-corona era, where demand is expected to increase in the future.

• Archives of Plastic Surgery
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• v.37 no.6
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• pp.823-826
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• 2010

Purpose: Meningomyelocele is the most common type of neural tube defect disease. Early surgical treatment is recommended to prevent central nervous system infection. Several reconstruction methods were reported previously regarding surgical wound defect closure following meningomyelocele excision. In this article, we report two successful patients using the bilateral fasciocutaneous sliding V-Y advancement flap as a covering for meningomyelocele defects. Methods: Two patients with meningomyelocele were evaluated. Both patients were male and received their operations on the 1st and 4th day of life. After neurosurgeons completed their part of the operation, the V-Y advancement flap was used to close the defect. Initially a bilateral V-shape incision design was made on the skin such that the base of the V-flap measures identical to the size of the wound defect. An incision was made down to the fascia in order to allow the V-flaps to slide into the defect. Subfascial dissection was performed up to 1/3 to 1/4 the length of the V-flap from the wound while minimizing injury to the perforating vessels. Results: Both patients were treated successfully and there was no evidence of complication in 2 months follow up. Conclusion: Several reconstruction methods such as local flaps, skin graft and myocutaneous flaps were reported regarding meningomyelocele surgical wound defect closure. Bilateral fasciocutaneous sliding V-Y advancement flap is an easy method without involving the underlying muscles or a secondary skin graft in a short operation time. Therefore we recommend this treatment option for reconstruction of the wound defect following meningomyelocele excision.

• Proceedings of the Korea Water Resources Association Conference
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• 2012.05a
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• pp.320-320
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• 2012

수문학적 의미의 일반적인 물순환은 증발, 응결, 강수 등 태양에너지와 중력에 의해 전지구적으로 반복되는 물의 재생산과정을 의미한다. 최근 들어 토목분야에서 언급되기 시작한 물순환시스템은 수문학적인 물수지(water balance)에 저류, 공급, 처리, 재이용 등 인공적인 요소를 감안하여 대상지역의 적절한 수요, 공급을 유지하는 시스템을 의미한다. 생활에서 물이 차지하는 중요성을 감안할 때, 지역의 수문학적 특성과 문화, 경제적 여건을 고려한 효율적인 물순환시스템의 구축은 지역발전의 정도를 가늠할 수 있는 지표라 할 수 있다. 본 연구는 물산업 선진국인 영국과 미국의 지역 물순환시스템 설계사례를 조사하고 초기단계인 국내사례와 비교하여 향후 설계지침 개발의 기초자료로 활용하기 위하여 수행되었다. 선진사례 조사는 2009년 이후 미국과 영국에서 수행된 세 건의 물순환 현황조사(water cycle study)와 미국에서 개발된 설계최적화 프로그램을 분석하였고, 국내사례로는 파주운정지구와 광교신도시 개발 시 수행된 물순환시스템 구축사례를 조사하였다. 해외 선진국 사례조사 결과, 물순환시스템 구축은 공통적으로 물순환망 현황조사, 물순환 계획수립, 지역현황 조사, 적용가능 기술조사, 설계 등 5단계를 거쳐 수행되었다. 이 중 가장 중요한 단계는 지역의 물수지와 가용 물 수요 및 공급 시스템을 조사하는 물순환망 현황조사로, 지역의 needs를 정확히 파악하고 양적, 질적 공급목표를 적절하게 선정하여 가장 효율적인 물순환망 계획을 수립하는 바탕이 되었다. 지역현황은 지역 법규 및 투자계획, 사회변화 예측 등 사회적 요소를 고려하는 단계로, 물순환 설계 선진사의 설계 최적화 프로그램의 경우 이러한 지역현황과 사회적 변화 예측의 반영에서 차별성을 갖고 있었다. 적용가능 기술조사의 경우 친환경, 저에너지 기술이 부각되던 추세에서 최근에는 지속가능성이 주요 고려사항 이었다. 국내사업 사례의 경우 규모가 작아 직접적인 비교가 불가하였으나, 5단계의 복잡한 최적화단계가 아닌 물순환망 분석결과와 이해당사자(stakeholders)의 needs를 바탕으로 치수안정성, 친수환경 보장 등의 목표를 수립하였다. 국내에서도 향 후 유역규모(watershed scale)의 대형 물순환기반 복합개발사업이나 대규모 해외사업 참여 시 필요한 기술력 축적의 차원에서 단계별 check list를 포함한 한차원 높은 물순환 설계지침 마련이 필요한 시점이라 하겠다.

• Journal of Korean Society of Transportation
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• v.21 no.3
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• pp.47-56
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• 2003

Considering the high density developments along the major traffic corridors in Seoul, transit-oriented street designs will be a very effective to control traffic congestion along the corridors. For testing the effectiveness, we selected. for our case study, Kangnam Street, which is one of the most highly developed corridors in Seoul The traffic study on Kangnam street in 2000 shows that the daily average bus speed is 11.73km/h, which is 5km/h lower than the auto speed. The Central Bus Lane system was applied on the Kangnam street to test impact on bus speed as well as auto speed. Simulation results show that with Central Bus Lane have been improved the travel speeds of bus as well as auto on Kangnam street from 14.4km/hr to 35.0km/hr and from 25.1km/hr to 26.1km/hr, respectively. The bus market share increases about 6-8 percentages. Especially, 13.4% of bus users are increased for long-distance trips.