• 한국철도학회논문집
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• 제20권5호
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• pp.637-648
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• 2017

본 논문에서는 이전 논문에서 제시한 불연속 프리캐스트 콘크리트궤도 유한요소 해석모델과 초기 변형 및 온도 변형 분석 결과를 이용하여 초기 변형과 온도에 의한 변형이 슬래브의 응력 분포에 미치는 영향을 분석하였다. 분석 결과에 따르면 프리캐스트 콘크리트 슬래브에 이미 발생해 있는 초기 변형과 온도 경사에 의한 변형이 있는 상태에서 열차하중이 작용하는 경우에는 슬래브 중앙, 모서리 중앙, 전단포켓 코너부 등 슬래브 상부에서 최대 인장응력이 발생하게 되어 열차하중만 작용하는 경우와 매우 다른 응력 분포를 나타낸다. 따라서 불연속 프리캐스트 콘크리트 궤도의 실제 취약부의 위치와 파괴모드를 예측하기 위해서는 슬래브의 초기 변형과 온도 변형을 고려하여 열차 하중에 의한 응력을 산정해야만 한다.

• Computers and Concrete
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• 제21권6호
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• pp.623-635
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• 2018

In order to research the influence of different recycled aggregate contents on the mechanical properties of pervious concrete, the experimental study and numerical simulation analysis of the mechanical properties of pervious concrete with five kinds of recycled aggregates contents (0%, 25%, 50%, 75% and 100%) are carried out in this paper. The experimental test were first performed on concrete specimens of different sizes in order to determine the influence of recycled aggregate on the compressive strength and splitting tensile strength, direct tension strength and bending strength. Then, the development of the internal cracks of pervious concrete under different working conditions is studied more intuitively by $PFC^{3D}$. The experimental results show that the concrete compressive strength, tensile strength and bending strength decrease with the increase of the recycled aggregate contents. This trend of reduction is not only related to the brittleness of recycled aggregate concrete, but also to the weak viscosity of recycled aggregate and cement paste. It is found that the fracture surface of pervious concrete with recycled aggregate is smoother than that of natural aggregate pervious concrete by $PFC^{3D}$, which means that the bridging effect is weakened in the stress transfer between the left and right sides of the crack. Through the analysis of the development of the internal cracks, the recycled aggregate concrete generated more cracks than the natural aggregate concrete, which means that the recycled aggregate concrete is easier to form a coalescence fracture surface and eventually break.

• 한국항공운항학회지
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• 제30권4호
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• pp.117-131
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• 2022

Human rights education is to acquire understanding and knowledge about human rights, to develop values, attitudes and character that respect human rights, to develop the ability to overcome human rights violations and discriminatory acts, and to protect and promote the human rights of others. In order to prevent human rights violations of the transportation vulnerable, such as the disabled, it is necessary to develop specialized human rights education plans for aviation security personnel to practice human rights perspectives. Therefore, in accordance with the 「National Civil Aviation Security Education and Training Guidelines」, specialized human rights education should be included in the initial aviation security education and regular education courses. The point is that there is a need to reexamine the aviation security education program for aviation security personnel based on the essential knowledge and educational contents for aviation security personnel to perform security screening tasks in the aviation security education course. When this happens, various efforts must be made to improve the human rights of the transportation vulnerable, such as the disabled, during the security screening process, so that human rights violations will be significantly reduced. In particular, it is necessary to enhance the ability to detect dangerous terrorist items such as weapons or explosives that can be used for illegal sabotage through practical security screening training. For aviation security and aircraft safety, efforts to improve the quality of aviation security personnel training, such as human rights training, must be continuously made while thoroughly preparing for terrorism in advance.

• 한국터널지하공간학회 논문집
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• 제20권5호
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• pp.855-867
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• 2018

터널 굴진면 전방에 연약대가 존재할 때에는 종방향 아칭에 의해서 굴진면 직전영역에 응력이 증가되어 터널의 안정성이 영향을 받는다. 따라서 굴진면 전방에 연약대 존재 여부 및 연약대의 특성을 파악하여 이에 대한 대비책을 마련하는 것이 중요하다. 굴진면 전방 연약대의 예측 방법은 물리탐사 및 수치해석적 방법과 터널지보 및 보강방안에 대한 연구는 많이 이루어 졌으나 굴진면 전방 연약대의 폭과 이격거리에 따른 이완영역에 대한 연구는 미비한 실정이다. 본 연구에서는 굴진면 전방에 연약대 존재 시 연약대의 폭과 이격거리에 따른 이완영역에 대하여 실내모형실험을 통해 규명하였다. 모형시험기에 주문진 자연사를 이용하여 함수비 3.8%로 모형 원지반을 조성하였으며 모형 연약대는 모형 원지반과 같은 자연건조 상태의 주문진 자연사를 샌드커튼 방식으로 강사하여 조성하였다 연약대 폭과 굴진면과 연약대 간 이격거리를 변화시키며 실험을 수행하였다. 모형시험기는 상하반단면 굴착이 구현 가능하도록 제작하였으며, 토조 바닥에 로드셀을 설치하고 지표에 변위계를 설치하여 터널굴착에 따른 연직응력 및 지표변위를 측정하였다. 지표침하는 연약대의 폭에 상관없이 굴진면과의 이격거리가 0.25D 이내에서 급격히 증가하였고, 수직응력 및 수평응력 또한 이격거리가 0.5D 이내에서부터 증가하는 경향이 나타났다. 실험결과 종방향 아칭의 영향은 터널 전방 1.0D 영역 내부터 형성된다고 판단된다.

• 한국항공운항학회지
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• 제16권3호
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• pp.21-30
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• 2008

As the low-cost carriers of the region enters the air transportation market, the domestic air transport circumstance is to be changed and each local autonomous entity conducts the feasibility study to develop the regional airport. But the airport is developed almost all by the goal of the policy and actually the valid basis of the airport development is often weak. To present the validity of the regional airport development Using the pre-feasibility study method the government performs I apply it to the airport development project of the Seo-san region. To present the validity of the regional airport development this study carries out the pre-feasibility study by the AHP analysis.

• 한국기계가공학회지
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• 제1권1호
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• pp.71-78
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• 2002

Since the early 1980's the use of zinc-aluminum alloy-coated steel sheet(Galvalume) for vehicular corrosion protection has increased drastically. It is consisting of 55%Al-43.4% Zn-1.6%Si. Galvalume has a good corrosion resistance, heat reflectivity and shiny appearance, which has a dendritic structure of alloy layer. It has a good corrosion resistance due to dendritic structure. But, this also has a weak point against moisture during long period of transportation as sheeted and or coiled without any relation of chromating on the surface of steel sheet or not because of high humidity and temperature. Here, We studied the corrosion mechanism by the moisture.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2004년도 춘계학술대회 논문집
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• pp.551-556
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• 2004

The Korean Train eXpress(KTX) which started in last April has got many complaints of passengers. This is caused by weak connections between KTX and traditional trains. This paper shows the methods to increase the connection in 3 points of view; business, operation and rolling stocks. For the flexible business, it is necessary that the connecting trains must be multi-purposefully for the satisfaction of KTX transferring passengers and existing commuting passengers. And the expanding of free class is needed. A free class is the base of business flexibility. In an operation point of view, I show the method that can decrease pains for getting transfer. Finally, for the effective using of rolling stocks, I propose that TC(trailer with control) car is added to existing locomotive and passenger coach set. In concluding, KTX needs strong connections with traditional trains. This will bring more competitive power with other transportation systems. And that method must get flexible and various service, in addition to effective and minimizing investment.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2004년도 춘계학술발표회
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• pp.622-628
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• 2004

In general, Reinforced Slopes by Shotcrete are difficult to inspect because of stiff Slope and highly Working Area. So the Inspection Techniques are needed by the Non-contact and Non-destructive. On this Study, Appling the safety method to finding the weak zones(cavity area, dampness area, etc.) by using the Infrared Thermal Technique That is detecting the Detail Thermal Difference on the Surface of Reinforced Slopes by Shotcrete.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2000년도 춘계학술대회논문집
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• pp.1367-1372
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• 2000

Recently, many new constructuion and large scale modification of railway are performed for cost down of goods delivery charge and effective transportation in various aspect. Although railway traffic is environmentally frendly in many part but weak in noise and vibration problem. For the reduction and efficient management of railway noise, first of all prediction of railway noise is necessarily requisted. In domestic and abroad many studies for prediction of railway nearby noise are done. In this study simple modelling technique is investigated for railway noise prediction when railway passes above elevated concrete bridge as well as ground. Predicted results are compared with measured results and it is known that suggested modelling technique can be used for more precise prediction of railway nearby noise.

• 대한수학회지
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• 제47권1호
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• pp.17-28
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• 2010

In this paper we deal with linear chance-constrained optimization problems, a class of problems which naturally arise in practical applications in finance, engineering, transportation and scheduling, where decisions are made in presence of uncertainty. After giving the deterministic equivalent formulation of a linear chance-constrained optimization problem we construct a conjugate dual problem to it. Then we provide for this primal-dual pair weak sufficient conditions which ensure strong duality. In this way we generalize some results recently given in the literature. We also apply the general duality scheme to a portfolio optimization problem, a fact that allows us to derive necessary and sufficient optimality conditions for it.