• The Journal of the Korea institute of electronic communication sciences
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• v.5 no.3
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• pp.227-232
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• 2010

Submarine cable system has been affected by humankind activities like trawl and stow net which has been threatening submarine cable in Korea. This research presents the protection ways of submarine cable through the analyses of cable faults on EAC system for 8 years.

• Transactions of the Korean Society of Automotive Engineers
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• v.12 no.1
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• pp.122-129
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• 2004

Finite element analysis was performed to analyze structural safety of a new heavy-duty direct injection diesel engine. A half section of the in-line 6-cylinder engine was selected as a computational domain. A mapping method was used to project heat transfer coefficients from CFD results of engine coolant flow onto the FE model. The accurate setting of thermal boundary condition on the FE model was expected to result in improved prediction of temperature, cylinder bore distortion, and stresses. Characteristics of high cycle fatigue were investigated by assuming the engine was operated under the following five loading conditions repeatedly; assembly force, assembly force with thermal loading, alternating maximum gas pressure loading at each cylinder combined with assembly force and thermal loading. Distribution of fatigue safety factor was calculated by using it Haigh diagram in which the maximum and the minimum stresses were selected from the five loading cases.

• Proceedings of the Korea Water Resources Association Conference
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• 2012.05a
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• pp.801-801
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• 2012

최근 과학 IT 패러다임은 기존 하드웨어, 소프트웨어 중심에서 폭발적으로 증가하는 데이터를 활용하여 정치 사회 경제 등 제반 이슈와 연계된 분석 예측으로 진화하고 있으며, 모바일 인터넷과 소셜 미디어 등장으로 데이터가 경제적 자산이 되는 빅데이터 시대가 도래하였다. 급속히 변화하고 복잡해진 사회구조와 재난환경으로 인해 인력에만 의존한 재난관리의 사각지대가 대형재난으로 이어질 우려가 크므로 다양한 재난전조(前兆)를 체계적으로 관리하여 선제적으로 예방하는 체계가 필요하다. 본 연구는 인터넷에 존재하는 재난관련 언론보도, 민원, 제보, 소셜 미디어 등의 비정형 데이터와 재난관련 정형 데이터(DB)를 융합 분석하여 재난전조를 사전에 감지하고 위험요소를 신속히 제거하는 빅데이터 기반 재난전조감지 체계를 제안한다. 최근 피해가 급증하고 있는 도시내수침수 피해 위험 예방을 위해 제안한 재난전조감지 체계를 적용하여 피해발생 위험요소 및 전조, 긴급 이슈 등을 감지하는데 활용하는 방안을 제안한다. 이는 전조를 감지하고 사전 침수 피해를 예측하여 피해 최소화 및 복구비용 절감, 저감능력 강화의 효과뿐만 아니라 위험요인 사전 차단 및 확산방지가 가능할 것으로 기대된다.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2019.05a
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• pp.133-134
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• 2019

우리나라는 협소한 국토구조 특성상 도로운송 위주의 화물운송체계가 정착되어 있어 내륙수송비 부담 증가, 교통 혼잡, 대기오염 및 소음, 도로파손, 대형교통사고 등 크고 작은 문제가 지속적으로 ${\cdot}{\cdot}{\cdot}{\cdot}$(중략)${\cdot}{\cdot}{\cdot}{\cdot}$ 따라서 본 연구에서는 물류비용 및 서비스를 좌우하는 수송비용과 물류인프라 초기투자비용을 최소화하면서 교통 혼잡, 온실가스배출 등 사회 환경 비용을 절감하기 위한 단절없는 인터모달 자동화물운송 시스템 개념을 정립하고 구성요소 및 요소기술을 ${\cdot}{\cdot}{\cdot}{\cdot}$(중략)${\cdot}{\cdot}{\cdot}{\cdot}$

• Journal of the Society of Naval Architects of Korea
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• v.38 no.3
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• pp.62-73
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• 2001

The interest in evaluation of structural intensity arises for practical reasons, because net energy flow distribution offers information of energy transmission path, positions of sources, and sinks of vibration energy. In this paper, structural intensity analysis of local ship structures using finite element method(FEM) is carried out. The purpose of this analysis is to evaluate the relative accuracy according to mesh fineness. The structural intensity of unstiffened and stiffened plates varying their mesh fineness is analyzed and the results are compared with those obtained by the assumed mode method. As results, the proper mesh size in qualitative/quantitative structural intensity analysis of plate structures is proposed. In addition, the propagation phenomenon of vibration energy is investigated for the thickness-varying flat plate, L-type plate, and box-girder structures.

• Journal of the Korea Society of Computer and Information
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• v.29 no.4
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• pp.155-160
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• 2024

Weather indexes such as temperature, humidity, wind speed and air pressure have been studied for diverse life-related factors: Food poisoning, discomfort, and others. In that, the Korea Meteorological Administration(KMA) has been released indexes such as 'Life industrial weather information', 'Safety weather information', and even 'picnic weather information' that shows how an weather like to enjoy picnic. Those weather-life effects also reveal on shopping preference such as an weather affects offline shopping purchase behaviors especially big-marts because they have outside leisure activity attribute However, since online shopping has not physical attribute, weather factors may not affect on same way to offline. Although previous researches have focused on psychological factors that have been utilized in marketing criteria, this research utilize KMA weather dataset that affects psychological factors. This research utilize 1,033 online survey for SEM analysis to clarify relationships between weather factors and online shopping purchase behaviors. As a result, online purchase intention is affected by temperature and humidity.

• Transactions of the Korean Society of Mechanical Engineers
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• v.16 no.10
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• pp.1877-1889
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• 1992

Upsetting is performed in open-die press forging to deform metal in all directions in order to enhance soundness of a product and reduce directionality of properties caused by casting. It is necessary to ensure sufficient forging ratio for subsequent cogging operations and consolidate the void along the centerline. To obtain these benefits, the upper die shape (dome and dished shape) is considered as an upsetting parameter. Thermo-viscoplastic finite element analysis has been carried out so as to understand the influence of upper die shape on the effective strain, hydrostatic stress and temperature in the upset-forged ingots without internal defects. The analysis is focused on the investigation into internal void closure in ingots with pipe holes and circular voids. The computational results have shown that the volume fraction of the void is independent of the circular void size and the closure of internal voids is much more influenced by the effective strain than the hydrostatic stress around the void. It is finally suggested that the height reduction must be over 35% for consolidation of internal voids.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.29 no.4 s.235
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• pp.563-569
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• 2005

This paper develops a finite element model of a cabover type large truck. The finite element model is for evaluating torsional stiffness of the frame of the large truck. The torsional test of the frame is conducted in order to validate the developed finite element model. A load cell is used to measure the load applied to the frame. An angle sensor is used to measure the torsional angle. An actuator is used to apply a load to the frame. A vertical upward load and a vertical downward load are applied to the frame in the torsional test. The frame's torsional stiffness is computed with the measured load and torsional angle in the torsional test. The finite element model of the large truck includes cab, deck and payload, suspension, and tire. Cab, deck, and suspension are modeled not to affect the frame's torsional stiffness. The simulation is performed with the developed finite element model for evaluating the frame's torsional stiffness. The simulation results show a very good correlation with the torsional test results in the tendency of changing of the frame's torsional stiffness not only with the direction of the applying load but also with the amount of the applying load. In addition, the simulation results predict the measured torsional stiffness of the frame with about $5{\%}$ error.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.35 no.10
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• pp.1211-1222
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• 2011

It is necessary to use prestressed modal analysis to calculate the modal frequencies and mode shapes of a prestressed structure such as a spinning blade, a preloaded structure, or a thermally deformed pipe, because the prestress effect sometimes causes significant changes in the frequencies and mode shapes. When the finite element model under consideration has a very large number of degrees of freedom, repeated prestressed modal analyses for investigating the prestress effects might become too computationally expensive to finish within a reasonable design-process time. To alleviate these computational difficulties, a Krylov subspace-based model order reduction, which reduces the number of degrees of freedom of the original finite element model and speeds up the necessary prestressed modal analysis with the reduced order models (ROMs), is presented. The numerical process for the moment-matching model reduction is performed directly on the full order models (FOMs) (modeled in ANSYS) by the Arnoldi process. To demonstrate the advantages of this approach for performing prestressed modal analysis, the prestressed wheel and the compressor impeller under their high-speed rotation are considered as examples.

• Journal of the Korean GEO-environmental Society
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• v.11 no.3
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• pp.23-32
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• 2010

In this study, Generally sandbag was used to reinforce slope or restore levee by using the in-situ material. To increase shear strength of sandbag, the Velcro system was effective for geosynthetic interface and make up for the weakness of shear strength between sandbag to sandbag. In this study, shear properties of geosynthetic-geosynthetic and geosynthetic-soil were evaluated from large scale direct shear tests. The cohesion and the angle of internal friction of each interface was evaluated. And laboratory model tests were performed to compare strength of reinforcement with strength of none reinforcement. As a result of this study, the cohesion and the angle of internal friction of each interface was increased, especially the cohesion was increased more than the angle of internal friction. Also according to the result of model test, the bearing capacity was increased by 20%.