• Journal of the Korean GEO-environmental Society
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• v.12 no.12
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• pp.13-20
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• 2011

The main objective of this paper is finding the influence factors and their degree of importance to steel liner's safety by investigating and evaluating the buckling incidents of steel tunnel liner under external water pressure. The study was based on the detailed investigation to the design conditions and incident shapes at 2m diameter waterway tunnel with a partially buckled internal steel liner and concrete backfilled lining as the raw water transmission pipe line of regional water supply project. Appropriate buckling theory capable of applying this incident points was selected by referring the existing literature and compared with the results of investigation. Also, hydrogeological characteristics of this site on buckling pressure was evaluated. The result of this study was shown that both the hydrogeological characteristics of upper geologic layers and proper tunnel construction are important factors on buckling at steel liner, and hydraulic gradient level should be decided according to the hydrogeological characteristics. This incident case analysis on steel liner of pressurized waterway tunnel was expected to provide more information for realizing the problems and improvements at each design, construction and maintenance stages.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.21 no.5
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• pp.109-127
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• 2011

Mobile Office is a new type of working method in the workplace that can be used at any time or anywhere by connecting to the network with mobile devices. This allows people to do their jobs without their physical presence in their offices to use computers. The elements in mobile office environment are advancing. They include the widespread distribution of the smart phones, the network enhancing strategy in a ubiquitous environment and expansion of the wireless internet; however, there are not enough security guidelines or policies against these threats on the new environment, the mobile office, although there is the revitalization policy of smart work supported by the government. CERT and ISAC, the known security system as of now, could be used for the secure mobile office, In this paper, suggestions are to be provided for strengthening the security of smart mobile office by analysing the functions of CERT and ISAC.

• The Journal of the Korea Contents Association
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• v.22 no.4
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• pp.458-467
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• 2022

The objective of this study is to investigate the meaning of children perceived by pre-service childcare teachers through metaphor analysis. To this end, data were collected from a group of 288 pre-service childcare teachers majoring in childcare at a university in Gyeonggi-do from the 4th week of May until the 2nd week of June 2021. As a result of the study, the meaning of children was categorized into 'being in need of care,' 'being affected by the environment,' 'being with personality,' 'precious and invaluable being,' 'being giving joy,' 'being who will lead the future,' 'pure and innocent being,' and 'being who develops teachers and parents.' Pre-service teachers showed the highest tendency to perceive children as 'beings in need of care' among the eight categories. The metaphorical expressions, 'sprout,' 'seed,' 'flower,' 'canvas,' 'sponge,' and 'mirror,' in descending order of frequency, were most commonly used among 138 metaphorical expressions. The findings of this study are expected to broaden the understanding of the pre-service teachers' perception of children and provide preliminary data for qualitative support and improvement plans for training pre-service childcare teachers in the future.

• Membrane Journal
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• v.33 no.4
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• pp.168-180
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• 2023

H₂ generation from renewable sources is crucial for ensuring sustainable production of energy. One approach to achieve this goal is biohydrogen production by utilizing renewable resources such as biomass and microorganisms. In contrast to commercial methods, biohydrogen production needs ambient temperature and pressure, thereby requiring less energy and cost. Biohydrogen production can reduce greenhouse gas emissions, particularly the emission of carbon dioxide (CO₂). However, it is also associated with significant challenges, including low hydrogen yields, hydrodynamic issues in bioreactors, and the need for H₂ separation and purification methods to obtain high-purity H₂. Various technologies have been developed for hydrogen separation and purification, including cryogenic distillation, pressure-swing adsorption, absorption, and membrane technology. This review addresses important experimental developments in dense polymeric membranes for biohydrogen purification.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.31 no.2
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• pp.89-94
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• 2023

Recently, domestic small airport development plans are being promoted centering on islands, and among them, Baengnyeong Island Airport is located very close to North Korea due to its geographical characteristics. In particular, since it is located in the P-518, which is prohibited airspace, it is essential to configure the arrival/departure flight procedure route similarly to the current ship in terms of securing flight safety. Therefore, in this study, a plan for airport location and facility scale was proposed by focusing on the runway operated for the purpose of aircraft operation through consultations with the Ministry of National Defense. It was proposed to meet the standards of the Airport Facility Act as an airport dedicated to domestic flights for airside facilities such as runway length and direction, target aircraft, landing pad, apron, runway and taxiway width appropriate for the topographical characteristics of Baengnyeong Island. As a result, the flight procedure is generally established as a two-way visual flight, but the 10-way arrival/departure procedure was planned to be changed to an instrument (non-precision) according to the specificity of the region. In addition, a flight procedure was established and presented for safe and systematic operation by reflecting the changes in airport facility size (landing pad, runway end safety area, etc.) following the change in instrument flight procedure in the visual flight procedure.

• Proceedings of the Korea Water Resources Association Conference
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• 2020.06a
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• pp.5-5
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• 2020

가뭄은 일반적으로 기상학적, 수문학적, 농업적 및 사회·경제적 가뭄으로 분류된다. 그 중 강수량 부족으로 인해 야기되는 기상학적 가뭄은 지역 사회에 직접적인 피해를 유발하는 도화선이 된다. 그러나 강우량 부족이 경제적, 사회적 피해로 전파되는 과정은 단순하지 않으며, 정량화가 어려운 실정이다. 가뭄 위험도는 수문기상학적 요인뿐만 아니라 자연재해에 대한 지역의 취약성의 맥락에서 파악되어야하므로, 가뭄 위험도 평가 방안은 위험도와 지역사회 사이의 관계를 규명하는 과정을 포함해야 한다. 이러한 문제를 해결하기 위해 가뭄 취약성(vulnerability)과 노출성(hazard)을 정량화하여 나타내는 지표를 적용한 가뭄 위험도 분석 방법이 주로 사용된다. 일반적으로 수용되는 취약성 개념은 개인 또는 그룹이 자연재해의 영향에 대처하고 이에 저항할 수 있는 능력을 의미하며, 노출성은 자연적 또는 인간이 유발할 수 있는 물리적 사건의 가능성을 나타낸다. 따라서 취약성은 지역의 문화적, 사회적 및 경제적 인자를 이용하여 정의된다. 반면 노출성은 주어진 시간 또는 영역 내에서의 특정 현상의 발생 확률에 따라 결정된다. 본 연구에서는 가뭄 취약성 지수 (Drought Vulnerability Index, DVI)와 가뭄 노출성 지수(Drought Hazard Index, DHI)를 이용하여 지역 가뭄 위험도를 평가하였다. 취약성 및 노출성 지수를 활용한 선행연구에서의 주요 쟁점은 연구자의 주관성을 배제하고 지역의 상황을 반영할 수 있도록 (1) 객관적이고 합리적인 변수의 선택과 (2) 각 인자들의 관계를 규정하는 가중치 정의 방법이다. 본 연구에서는 확률론적 접근방법을 적용한 위험도 평가 방안을 제시하고자 하였다. DVI를 산정 시 지역에서 지배적인 사회경제적 인자를 선택하기 위해 주성분분석(PCA) 기법을 활용하였으며, DHI는 이변량 가뭄 빈도 분석에 의해 산정된 특정 가뭄사상의 발생 확률로 정의되었다. 본 연구에서는 국내에서 가뭄 위험도가 가장 높은 것으로 평가되는 충청북도 및 충청남도를 대상지역으로 선정하고 지역 위험도를 평가하였다. 그 결과 가장 가뭄 위험도가 높은 지역은 충청북도에서는 청주시, 충청남도에서는 공주시로 분석되었다. 특히 청주시는 DVI가 매우 높지만 DHI는 상대적으로 작게 나타났으며, 반면 공주시는 DHI와 DVI가 지역 내에서 가장 높게 산정되었다.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.5D
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• pp.665-675
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• 2008

The objective of this paper is to provide an approximate cost estimating model for tunnel that can be utilized both in quick construction cost estimating for design alternatives, and in evaluating efficiently the cost effects according to the environmental changes during design and construction stage. To meet this requirement, this study analyzes critical cost factors influencing tunnel construction costs. The cost factors include 7 elements such as rock drilling method, advancing method, type of detonator, loader capacity, unit weight and soil volume change factor, length of tunnel. This paper investigates the cost variance according to the change of the cost factors. The result is expected to be used in formulating approximate tunnel cost estimating model.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.5D
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• pp.677-684
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• 2008

The paper provides an approximate cost estimating model that can be used for tunnel. Based on the previous study analyzed critical factors that have impact on tunnel construction cost, this paper establishes a cost variance index table that reflects the cost impacts due to the change of the critical cost factors. An estimating procedure is described utilizing the index table. For the verification of the suggested model, the comparison of the estimated construction cost with real project cost is performed. The estimated results range from 95%~111% of the real project costs. As an approximate tunnel cost estimating model, the model can be utilized to quickly estimate tunnel construction costs based on the conceptual information at the planning stage and to efficiently make a decision on design alternatives.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.3D
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• pp.339-346
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• 2008

The research was conducted to investigate the characteristics of lateral wheel path distributions (wandering) in different traffic lanes. The lateral wheel path distributions may affect pavement life and various distress types. The results presented that the normal distribution curve with symmetry was observed in the 2-lane and 3-lane roads. In the case of the 2-lane road (on one direction), the wanderings were 70-95cm, and 70-85cm for the 1st and 2nd lanes, respectively, while in the case of the 3-lane road (on one direction), 50-60cm, 65-85cm, and 80-95cm for the 1st, 2nd, and 3rd lanes, respectively. In addition, the 1st lane vehicles tended to pass on the right side to avoid the opposite side vehicles, while the outside lane vehicles tended to pass on the left side to avoid the walkway.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.2B
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• pp.153-160
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• 2006

To recommend ecological flow for major tributaries in Han River basin, the Instream Flow Incremental Methodology (IFIM) have been applied. In particular physical habitat simulation using PHABSIM have been selected for microhabitat variables and QUAL2E model have been used to implement macrohabitat simulation. Habitat Suitability Criteria (HSC) for different life stages in accordance with different hydraulic variables (depth and velocity) have been presented by the field surveying data. We review IFIM procedures and discuss limitations of habitat simulation with specific reference to Han River basin. The results of this research can be used as reference flow for estimation of instream flow in Han River.