• Journal of the Korea institute for structural maintenance and inspection
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• v.27 no.6
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• pp.120-129
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• 2023

To evaluate the vertical loads on railway bridges, conventional load tests are typically conducted. However, these tests often entail significant costs and procedural challenges. Railway conditions involve nearly identical load profiles due to standardized rail systems, which may appear straightforward in terms of load conditions. Nevertheless, this study aims to validate load tests conducted under operational train conditions by comparing the results with those obtained from conventional load tests. Additionally, static and dynamic structural behaviors are extracted from the measurement data for evaluation. To ensure the reliability of load testing, this research demonstrates feasibility through comparisons of existing measurement data with sensor attachment locations, train speeds, responses between different rail lines, tendency analysis, selection of impact coefficients, and analysis of natural frequencies. This study applies to the Dongho Railway Bridge and verifies the applicability of the proposed method. Ten operational trains and 44 sensors were deployed on the bridge to measure deformations and deflections during load test intervals, which were then compared with theoretical values. The analysis results indicate good symmetry and overlap of loads, as well as a favorable comparison between static and dynamic load test results. The maximum measured impact coefficient (0.092) was found to be lower than the theoretical impact coefficient (0.327), and the impact influence from live loads was deemed acceptable. The measured natural frequencies approximated the theoretical values, with an average of 2.393Hz compared to the calculated value of 2.415Hz. Based on these results, this paper demonstrates that for evaluating vertical loads, it is possible to measure deformations and deflections of truss railway bridges through load tests under operational train conditions without traffic control, enabling the calculation of response factors for stress adjustments.

• Nuclear industry
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• v.16 no.8 s.162
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• pp.68-77
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• 1996

한전 전력연구원은 최근 월성 원자력 1호기 주증기관 배관 설비의 안전성 및 운전 신뢰도를 크게 향상시킬 `배관진동 해석기술`을 개발하였다. 이 기술은 소음진동연구팀이 연구에 착수한지 2년만에 성공한 것으로, 10년 이상 진동 문제로 어려움을 겪고 있는 월성 원자력 1호기 주증기 배관의 유체 유동, 구조물의 동적$\cdot$정적 특성을 규명, 진동 감쇠 장치를 설치하게 됨으로써 배관의 최대 진동값이 허용 기준치 이하로 줄어들어 시스템 신뢰성 및 원전 설비의 안전성을 크게 높인 것으로 평가되고 있다. 전력연구원은 앞으로 이 기술을 월성 1호기 나머지 2개 라인 및 타 발전소에까지 적용시켜 대형 배관 구조물의 해석 기술을 선진국 수준으로 향상시킬 계획이다.

• Information and Communications Magazine
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• v.29 no.3
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• pp.17-25
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• 2012

수백만 네트워크 요소가 이동하면서 구성정보가 계속 변화하고 상태정보도 매우 동적인 미래인터넷 특성을 가진 환경을 관리하기 위해선 기존의 단순하고 정적인 망에 적합하게 설계된 중앙 집중방식의 망 및 서비스 관리에 대한 혁신적인 구조 변화가 필요하다. 본 고에서는 현재 인터넷이 구조적으로 가지고 있는 한계점들을 관리 차원에서 극복하기 위한 미국, 유럽, 및 아시아 지역의 미래인터넷에 대한 최근의 다양한 연구 동향에 대해서 살펴보고 향후 나아갈 방향에 대해서 전망해 보도록 한다.

• Elastomers and Composites
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• v.46 no.3
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• pp.186-194
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• 2011

Natural fiber/natural rubber composites were fabricated by uniformly compounding natural rubber and cellulose- based natural fiber kenaf and then by compression molding. The effect of kenaf fiber content on their vulcanization behavior, hardness, tensile properties, tear strength and static and dynamic properties was investigated. The contents of kenaf fiber in the composites were 0, 5, 10, 15, and 20 phr, compared to natural rubber and additives. The result indicated that various properties of natural rubber depended on the kenaf fiber content. With increasing kenaf fiber content, the torque for vulcanization of natural rubber was increased whereas the vulcanization time was reduced as well. The hardness, tensile modulus and tear strength of kenaf/natural rubber composites were gradually decreased with the fiber content whereas the tensile strength and elongation at break were decreased. Also, with increasing the kenaf fiber content the dynamic property of natural rubber was changed more greatly than the static property. The loss factor, which is closely related with the damping or absorption of the energy given to natural rubber, was proportionally increased with the fiber content.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.13 no.2
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• pp.243-252
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• 1993

Undrained cyclic simple shear tests and undrained cyclic triaxial tests were performed on silt containing sand in order to investigate the effects of silt contents on the liquefaction strength and shear characteristics of the sand. From the view that the difference of liquefaction strength for different content of silt stems from dilatancy characteristics of the sand, stress-dilatancy relation of the sand was obtained from drained triaxial test in which the mean stress was kept constant. Considerations on liquefaction behaviors were made by comparing the drained and undrained behaviors of sands during static shear test. It is concluded that ${\lambda}$-value of the stress-dilatancy relation will be closely related to the liquefaction strength.

• Magazine of the Korea Concrete Institute
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• v.8 no.1
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• pp.130-137
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• 1996

본 연구는 정적 및 동적하중 재하상태에서 배합조건을 달리한 콘크리트의 파괴특성을 조사하고자 3점 휨 실험을 실시하였다. 실험은 물-시멘트비를 일정하게 유지한 상태에서 슬럼프 값을 변화시키는 경우와 슬럼프 값을 일정하게 유지하면서 물-시멘트비를 변화시키는 경우로 구분하여 배합비를 달리한 6가지 배합형태의 무근콘크리트 시편 54개를 제작하였다. 실험결과에 의하여 콘크리트의 파괴에너지(Gf)와 특성길이(lch)를 구한 수 이를 강도특성(f'c, fsp , Ec, ff)과의 상관관계를 규명하고 파괴에너지(Gf)를 이용한 배합설계의 타당성을 검토하였다.

• Proceedings of the KIPE Conference
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• 2011.07a
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• pp.192-193
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• 2011

자기유도방식 무선전력전달용 DQ 인버터의 정적 동작 특성 및 동적 응답 특성을 해석하는데 복소 라플라스 변환을 페이저 변환된 회로에 적용하는 방법을 사용하였다. 최근에 발표된 복소 라플라스-페이저 변환이론이 교류 컨버터의 동적특성을 해석하는데 있어 실용적으로 아주 유용하다는 것이 연구를 통해서 확인되었다. 기존의 라플라스 변환을 복소수 영역으로 확대한 복소 라플라스 변환을 페이저 변환된 회로에 적용하면 전달함수를 구할 수 있어, 시스템의 안정도 분석과 제어기 설계가 가능해진다. 본 논문에서는 이론식을 유도하고 시뮬레이션을 통해 검증하였다.

• The Journal of the Korea Contents Association
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• v.9 no.4
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• pp.364-371
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• 2009

We analyzed romance of the three kingdoms written by Luo Guanzhong by using complex network to compare its properties with those of social network. The three kingdom network has a scale free and hierarchical network properties. Human-human interaction networks are dramatically changing in response to time and space. Due to lack of the dynamic interacting data, the researches only focus to analysis for properties of the statical networks. The romance of the three kingdoms is a Chinese historical novel based upon events from the end of the Han Dynasty, the Three Kingdoms era of China, and the reunification of the land. There are over a thousand characters, over a three thousand human-human interactions, and the dynamic changed in human-human interactions in the historical novel. Here, we introduce that a possible method for analyzing about dynamic changing of the complex network.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.20 no.4
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• pp.463-468
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• 2007

Some network equipments made in Korea were exposed to severe earthquake in Japan several years ago. More than a hundred slim base transfer network stations had been seized with the severe earthquake at Nigata and it was reported that less than fifteen sets showed blackout by interruption of electricity, not by the structural failure. The purpose of this paper is to check the structural safety of the network equipments by performing table test, and the static and dynamic finite element analysis. For the dynamic test, the station weighing 200 kg was subjected to the Zone 3 earthquake loading of GR-63-CORE on the shaking table to obtain the dynamic responses to compare with the analysis results. It is shown that the FE analysis results are a little bit larger than that of the experimental values. And the sensitivity analysis and optimization for the natural frequency is performed and it is found that the first natural frequency is sensitive to small design change as shown in the results. And the dynamic response of optimized design is less than the original design.

• Proceedings of the Korean Society of Computer Information Conference
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• 2020.07a
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• pp.397-400
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• 2020

본 논문에서는 문화유산 현장에서의 몰입형 교육을 위한 VST(Video See-through) 방식의 HMD(Head Mounted Display) 기반 XR(eXtended Reality) 체험 프레임워크를 제안한다. 매장문화재적 요소가 강한 문화유산 현장의 경우 실물이 남아있지 않아 교육 및 체험 측면에서 흥미로운 정보 전달이 어렵다. 최근 모바일 기기의 대중적인 확산에 따라 이를 이용해 문화유산 현장에 소실된 문화유산을 AR(Augmented Reality)로 복원 및 시각화하거나 관련 정보를 제공하는 연구들이 이루어졌으며, 나아가 OST(Optical See-through) 방식의 안경형 AR 디스플레이를 활용하는 사례들도 등장했다. 그러나 이러한 연구들은 기기의 특성으로 인해 몰입감과 사용성 측면에서 한계점을 보였으며, 단순히 소실된 문화유산의 복원된 모습을 정적으로 시각화하는 것에 그쳐 문화유산 현장에 내재된 동적인 역사 스토리를 재현한다는 측면에서 부족한 점이 있었다. 본 논문에서는 문화유산 현장에서 VST-HMD를 이용하여 AR 기반의 정적 문화유산 시각화뿐만 아니라 VR(Virtual Reality) 기반의 동적 역사 스토리 애니메이션을 제공하는 XR 체험 프레임워크를 제안하여 더욱 몰입감 있고 만족스러운 문화유산 교육을 제공하는 방안에 대해 검토한다.