• Journal of the Korea institute for structural maintenance and inspection
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• v.25 no.6
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• pp.235-244
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• 2021

This study analyzes the applicability of limit state design method on bridge evaluation by considering the experiment of the existing bridge. The test strength of the member is obtained from the PSC beam bridge experiment. The test strength is compared with the calculated strength obtained from the statistical characteristics of material test strength and the two values are almost the same. The response modification factor and dynamic impact factor are obtained from the vehicle loading test. The rating factor is calculated by applying limit state design method as well as current evaluation method and the results are compared. The reliability index of the test bridge is calculated by using the statistical properties of the member strength obtained from material test and simulation. When the statistical properties of the PSC beam tested in this study are applied, the reliability index with a larger value was obtained than the reliability index obtained with the statistical properties of the design code.

• Journal of Bio-Environment Control
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• v.24 no.3
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• pp.147-152
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• 2015

In order to develop the cooling load estimation method in the greenhouse, the cooling load calculation formula based on the heat balance method was constructed and verified by the actual cooling load measured in the fog cooling greenhouse. To examine the ventilation heat transfer in the cooling load calculation formula, we measured ventilation rates in the experimental greenhouse which a cooling system was not operated. The ventilation heat transfer by a heat balance method showed a relatively good agreement. Evaporation efficiencies of the two-fluid fogging system were a range of 0.3 to 0.94, average 0.67, and it showed that they increased as the ventilation rate increased. We measured thermal environments in a fog cooling greenhouse, and calculated cooling load by heat balance equation. Also we calculated evaporative cooling energy by measuring the sprayed amount in the fogging system. And by comparing those two results, we could verify that the calculated and the measured cooling load showed a relatively similar trend. When the cooling load was low, the measured value was slightly larger than calculated, when the cooling load was high, it has been found to be smaller than calculated. In designing the greenhouse cooling system, the capacity of cooling equipment is determined by the maximum cooling load. We have to consider the safety factor when installed capacity is estimated, so a cooling load calculation method presented in this study could be applied to the greenhouse environmental design.

• Proceedings of the Korea Water Resources Association Conference
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• 2009.05a
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• pp.900-904
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• 2009

연구에서는 HEC-RAS 모형을 이용한 부등류 모의를 통하여 댐 방류수의 유하시간을 산정하고 이를 실시간 댐 방류수의 봉부자 추적실험에서 산정된 유하시간과 비교검증 하였다. 대상구간은 충주댐지점부터 여주대교까지 총 63.6km에 이르는 남한강 본류 구간으로 164개 단면으로 나누어 부등류 모의를 하였다. 유하시간 실험은 센서가 내장된 봉부자를 최초 시작지점에 투척하여 주요 교량에서 봉부자를 관측하여 최초 투척된 시간으로부터 교량을 통과하는 시간을 관측하는 방법을 사용하였다. HEC-RAS 부등류 모의 결과 2007년 8월 7일 방류량(680CMS)의 유하시간은 약 13시간으로 산정되었고 봉부자 추적자 실측자료를 통한 유하시간은 11.5시간으로 산정되어 실측치가 모의치보다 유하시간이 빠른 것으로 나타났다. 구간별로 살펴보면 HEC-RAS 모형의 모의결과는 수행교에서 충주조정지는 1.4시간 느리게, 목계교에서 남한강교는 1.0시간 빠르게 모의되었으나 나머지 구간에서는 실측치와 대체로 일치하였다. 본 연구는 유하시간 실험 구간 및 구간과 동일한 조건으로 모의함으로서 모형을 보정하기 위한 실측 유하시간 자료를 확보하였으며, 이러한 실측자료를 토대로 보정된 모형의 매개변수를 이용함으로서 대상 수계의 방류량별 유하시간을 산정하는데 정확성을 제고하고 홍수기 댐 운영 및 홍수예경보에 반영될 수 있을 것으로 기대된다.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2011.11a
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• pp.234-237
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• 2011

본 논문에서는 모델 기반 카메라 추적 시 필요한, 사전 정의 된 실측 모델의 정확성이 카메라 추적의 정확성에 미치는 영향에 대하여 논의한다. 이를 위하여 모델 기반과 특징점 기반의 카메라 추적에 가중치를 두고 혼합시켜 이용하는 하이브리드 카메라 추적 방법을 사용하고, 이 방법을 활용한 상호작용형 모델링(interactive modeling)을 이용하여 실측 모델을 제작한다. 또한, 상호작용형 모델링 과정에서 생기는 실측 모델의 오차로 인해 발생하는 카메라 추적 오차를 Cramer-Rao 하한(lower bound)을 이용하여 정의하고, 이 둘의 상관관계를 실험적으로 도출한다. 이를 통해 사전 정의된 실측 모델이 가질 수 있는 오차의 하한을 실험적으로 검증한다.

• Journal of Korean Society of Transportation
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• v.16 no.3
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• pp.101-111
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• 1998

현재 고속도로 교통관리시스템(FTMS)에 사용되고 있는 차량 검지기는 주로 루프 식 검지기가 이용되고 있으나, 유지관리에 많은 어려움이 있다. 본 연구에서는 이러한 문제 점을 갖고 있는 루프 검지기를 대체하기 위한 대체 검지기를 개발하는데 그 목적이 있다. 자기 검지기 신뢰도 평가는 현장 실험으로 이루어지며 비디오 촬영 및 루프 검지기, test car를 이용하여 교통량·속도·점유율의 기준자료를 마련하고 자기 검지기 자료와 비교·분석 및 통계적 검정을 실시하였다. 1차 실험과 2차 실험의 결과, 교통량과 속도는 실측자료와 유사했으나 점유율은 실측치와 다소 차이가 발생함을 보였다. 향후 점유율에 대한 보정이 이루어진다면 현재 사용중인 루프 검지기를 대체할 수 있을 것으로 기대된다.

• Journal of Korean Association for Spatial Structures
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• v.7 no.3 s.25
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• pp.67-77
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• 2007

The purpose of this study is to provide fundamental heating design data for the large public enclosures as gymnasium. This study executed indoor thermal environment verification of the existing gymnasium by measuring temperature distribution with and without heating the space in winter. Heating loads from human body was not considered. We examined various indoor thermal environment factors of the large enclosed space in this study which include vertical and horizontal temperature distribution, supply and return air flow feature, thermal comfort environment feature, amount of ventilation and etc.

• Journal of Korean Association for Spatial Structures
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• v.7 no.6
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• pp.91-101
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• 2007

The purpose of this study is to provide fundamental cooling design data for the large public enclosures as gymnasium. This study executed indoor thermal environment verification of the existing gymnasium by measuring temperature distribution with and without cooling the space in summer. Colling loads from human body was not considered. We examined various indoor thermal environment factors of the large enclosed space in this study which include vertical and horizontal temperature distribution, supply and return air flow feature, thermal comfort environment feature, amount of ventilation and etc.

• The Journal of the Acoustical Society of Korea
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• v.23 no.6
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• pp.428-436
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• 2004

Synthetic Aperture Sonar is a technique of extending Physically limited length of an array by signal processing to enhance bearing resolution of a system. The previous techniques estimate most or away shapes as linear. so when towed array shapes are distorted. this can create a deviation from actual situation. In this paper. we estimated perturbed away shapes. and compensated distortion by using estimated array shapes and synthesized arrays in aperture domain. As experimental data, we used the one obtained from towed array in neighboring waters of the Korean peninsula. We extended array by compensating differences in time and spatial position between overlapped subarrays by using SAS techniques. In simulation results. we confirmed that the bearing resolution was enhanced.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38B no.10
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• pp.851-860
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• 2013

To overcome a scarcity of radio resources to mobile broadband service, the usage of TV white space gains much attraction around the world. This paper carries out an interference analysis either by performing realistic experiments or by executing statistical Monte-Carlo simulation to exploit interference probability. The results obtained from experiments are compared to those from simulations in order to clarify the coexistence of utilization of TV band devices (TVBD) in indoor circumstances. Along the execution of our experiment in the presence of DTV receiver, we apply to a variety of transmission parameters proposed in FCC for TVBD. According to experimental and simulation works, the allowable transmission powers of TVBD systems are exploited for the plausible which are coexist on the first as well as the second adjacent frequency bands. Throughout results, it can conclude that TVBD systems can be coexisted via achieving proper transmission powers depending on the locations of themselves without showing harmful interference to DTV reception.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.7 no.4
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• pp.329-339
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• 1995

To clarify the surface drift velocity in gravity waves. experimental data measured in a two-dimensional wave flume were compared with theoretical values predicted by the Stokes 2nd- and 5th- order theories as well as by the conduction solution or Longuet-Hinggins (1953). Relative water depth and wave height ranged 0.040.13. For a closed flume condition, Stokes 2nd-order theory gives lower values than the experimental data, and the differences increase as both relative water depth and wave height increase. Based on the observed data of the surface drift velocities, a modified Parabolic model of the return current velocity Profile has been suggested, which is Proved to fit better to the existing experimental data of mass transport velocity profiles in a closed wave flume than the models of Longuet-Hinggins (1953) and Stokes wave theories do.