• Journal of Korean Society of Transportation
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• v.35 no.4
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• pp.278-291
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• 2017

Effective installation and operations of traffic safety signs in the advance warning area is of considerable interest for safer traffic management at freeway work zones. This study evaluated the feasibility of traffic safety sign installation based on a driving simulation experiment to take drivers' responsive characteristics into consideration. Both the compliance rate for speed limit and a lane-changing safety index were used for evaluating a set of driving simulation scenarios. It was identified that providing speed limit signs to reduce speed in advance and afterward guiding lane-changing could lead to safer maneuvering of vehicles entering work zones. The outcomes of this study are expected to be useful for revising freeway work zone management policies toward crash prevention.

• Journal of Korean Society of Transportation
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• v.34 no.4
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• pp.354-372
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• 2016

This study identified factors affecting the crash severity at freeway work zones. A nice feature of this study was to take into account the characteristics of work zone traffic management in analyzing traffic safety concerns. In addition to crash records, vehicle detection systems (VDS) data and work zone historical data were used for establishing a dataset to be used for statistical analyses based on an ordered probit model. A total of six safety improvement strategies for freeway work zones, including traffic merging method, guidance information provision, speed management, warning information systems, traffic safety facility, and monitoring of effectiveness for countermeasures, were also proposed.

• Journal of the Korean Geosynthetics Society
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• v.18 no.4
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• pp.225-242
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• 2019

Rockfall failure at the access road to Seokguram were occurred due to the earthquake on September 12, 2016. A detailed investigation was carried out in order to find out the cause of the rockfall, to identify the risk of the entire sites, and to prepare proper countermeasure methods and mitigation. We checked for geological and topographical characteristics of overall slopes alongside the access road to Seokguram and made a face map. In addition, we analyzed topographical factors caused by the earthquake through calculating a degree of slope, degree of bearing, upslope contributing area, and wetness index with the use of shading relief map. As a result, we confirmed that the large rockfall occurred with a weak section. In this study, we also evaluated the overall slope stability of the entire access road to Seokguram in order to classify it into danger and caution zones depending on the risk of collapse.

• The Journal of the Acoustical Society of Korea
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• v.40 no.2
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• pp.155-160
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• 2021

This paper proposes an automatic method for detecting snore sound, one of the important symptoms of sleep apnea patients. In the proposed method, sound signals generated during sleep are input to detect a sound generation section, and a spectrogram transformed from the detected sound section is applied to a classifier based on a Convolutional Bidirectional Gated Recurrent Unit (CBGRU) with attention mechanism. The applied attention mechanism improved the snoring sound detection performance by extending the CBGRU model to learn discriminative feature representation for the snoring detection. The experimental results show that the proposed snoring detection method improves the accuracy by approximately 3.1 % ~ 5.5 % than existing method.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.11 no.10
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• pp.1835-1844
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• 2007

Recently there have been some positive evidences on the effects of learning in a virtual environment. However, most of these educational VR systems were not deeply considered in the design of drawing a learner's attention on lesson contents, which would help enhance retained memory. Hence, a study was conducted to measure 17 subjects' attention states using EEC, ECG, GSR, and eye-tracking and their behaviors while they were given guided search task or exploration task in a virtual environment consisting of five major events. It also analyzed the subject's remembered items after their VR experiences using a surrey. This paper Int describes an overview of the ocean virtual environment used in this study, and it then explains the experimental design, apparatus, and method. It will also discuss the results by a detail analysis (in a whole VR session as well as event-related 10-second 33 sub-sessions) with the subjects' attention states and their retained memory after the learning.

• Proceedings of the KIEE Conference
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• 2001.11a
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• pp.259-261
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• 2001

전차 선로용으로 적용되는 직류 피뢰기의 설계 기술을 소개하였다. 현재 국내에 사용되는 전차 선로 서지 보호용 직류 피뢰기는 전량 수입에 의존하고 있다. 안전한 피뢰기를 설계하기 위해서 적용 구간의 임펄스 서지 환경을 파악하고 이에 맞는 적절한 내량의 피뢰기를 설계하는 것이 요구된다. 특히 직류 구간의 경우 과도 서지 발생의 형태가 기존 계통 환경과 다르기 때문에 피뢰기 보호범위와 정격의 설정에 주의가 요구된다.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.479-480
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• 2011

관로내 케이블 포설시 케이블 허용장력이 포설장력을 초과하지 않도록 주의해야 한다. 또한, 케이블 포설 도중 Kink가 발생하지 않도록 케이블 드럼을 반드시 세워서 포설해야 하고, 케이블 드럼을 눕혀서 포설해서는 안 된다. 또한, 허용전류를 고려하여 케이블 상호간의 간격을 일정하게 유지해야 한다. 관로 내 케이블을 설치할 경우 직선구간 뿐 아니라 굴곡구간에도 설치되므로 포설측압이 허용측압을 초과하지 않도록 시설해야 한다. 측압에 견디기 위해서는 케이블 포설시 곡률 반경을 케이블 외경의 10배 이상으로 유지하는 것이 중요하다.

• Proceedings of the KIEE Conference
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• 2004.04a
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• pp.238-240
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• 2004

현재 우리나라에서 사용 중인 신호시스템은 지상신호 방식인 자동폐색장치(ABS)를 사용한다 이는 선로를 패색구간으로 배분한 후, 각각의 패색 구간에 설치된 신호기에 의해 열차의 이동을 실행한다 이러한 신호체계에 문제점이 발생할 경우, 기관사에게 주의를 환기시켜 강제적으로 열차를 정지시키는 역할을 하는 자동열차정지장치(ATS)가 1969년부터 도입, 사용 중에 있다. 본 논문에서는 ATS 시스템의 고속, 고밀도 운전 적용 가능성 및 차상신호방식 사용시의 ATS 적용 가능성에 대해 분석한다.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.20 no.6
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• pp.117-132
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• 2021

Due to the terrain in Korea, there are many road sections passing through mountainous areas. During the winter, there is a higher risk of traffic accidents, due to black ice caused by the lack of sunlight. Despite domestic road freezing safety measures, accidents caused by road freezing results in severe traffic accidents. Under these considerations, this study analyzed whether traffic safety signs that change in response to the external temperature help drivers recognize frozen road segments. The study was conducted through analysis of the effect of the signs on a driver's perspective. For the signs under development, out of the signs designed by experts, the sign design which received the highest visibility and effectiveness evaluation ratings from the general public was selected. The sign was implemented through Virtual Reality (VR) and installed on the right side of the road to analyze the effect on gazing and driving behavior. As a result of analyzing the driver's driving behavior, a speed reduction of about 7km/h or more was found in the sign section. Therefore, It was found that the existence of the sign had a strong relationship with the rate of the drivers' speed reduction.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2004.09a
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• pp.317-320
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• 2004

정압주입시험(Constant Head Injection Test, CHIT)은 결정질 암반의 구간별 수리전도도 및 투수계수를 구하는 전통적인 수리시험방법이다. 본 연구에서는 Visual Modflow 수치코드를 사용하여 정압주입시험에 대한 부정류 모의를 수행하였다. 수치모의 결과 주입공에서 매질로 시간별 주입되는 유량은 30분이 경과한 후부터 거의 일정하게 유지되는 양상을 확인할 수 있는데, 현장에서 정압주입시험을 할 때 적어도 30분 이상의 시첩을 실시해야 함을 알 수 있었다. 시험구간에 따른 수리전도도 값은 시험구간의 크기에 상관없이 거의 일정한 값을 보이고 있어, 시험구간의 크기는 정압주입시험에서 크게 유의하지 않아도 된다고 판단된다. 그러나, 시험구간별 주입 압력에 따른 수리전도도 값의 변화를 살펴본 결과, 시험 구간의 크기와 주입 압력 값이 클수록 산출되는 수리전도도 값이 매질의 수리전도도 값과 차이가 나는데, 현장조사에서 시험구간과 주입 압력 값에 대한 고려가 있어야 함을 지시한다. 매질의 수직적 이방성에 따른 모의결과 $K_{zz}$ / $K_{xx}$ and $K_{yy}$ 값이 작아질수록 수리전도도 값이 작아지는데, 현장조사 결과를 해석함에 있어 매질의 수직적 이방성은 주의를 기울여야 한다.