• Safety and Health at Work
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• 제11권4호
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• pp.405-417
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• 2020

Background: Electrical socket outlets are used continuously until a failure occurs because they have no indication of manufacturing date or exchange specifications. For this reason, 659 electrical fires related to electrical socket outlets broke out in the Republic of Korea at 2018 only, an increase year on year. To reduce electrical fires from electrical socket outlets, it is necessary to perform an accelerated test and analyze the thermal, insulation resistance, and material properties of electrical socket outlets by installation years. Methods: Thermal characteristics were investigated by measured the temperature increase of electrical socket outlets classified according to year with variation of the current level. Insulation resistance characteristics was measured according to temperature for an electrical socket outlets by their years of use. Finally, to investigate the thermal and insulation resistance characteristics in relation to outlet aging, this study analyzed electrical socket outlets' conductor surface and content, insulator weight, and thermal deformation temperature. Results: Analysis showed, regarding the thermal characteristics, that electrical socket outlet temperature rose when the current value increased. Moreover, the longer the time that had elapsed since an accelerated test and installation, the higher the electrical socket outlet temperature was. With respect to the insulation resistance properties, the accelerated test (30 years) showed that insulation resistance decreased from 110 ℃. In relation to the installation year (30 years), insulation resistance decreased from 70 ℃, which is as much as 40 ℃ lower than the result found by the accelerated test. Regarding the material properties, the longer the elapsed time since installation, the rougher the surface of conductor contact point was, and cracks increased. Conclusion: The 30-year-old electrical socket outlet exceeded the allowable temperature which is 65 ℃ of the electrical contacts at 10 A, and the insulation resistance began to decrease at 70 ℃. It is necessary to manage electrical socket outlets that have been installed for a long time.

• 한국컴퓨터정보학회논문지
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• 제27권12호
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• pp.141-149
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• 2022

본 연구에서는 공공 CCTV 함체 관리를 위한 블록체인 기반 함체기록 관리 시스템을 설계하였다. CCTV 영상 기록은 함체를 거쳐 관제센터까지 전송되기 때문에 영상기록의 변조 및 훼손 방지를 위한 함체 관리가 매우 중요하다. 최근 CCTV 함체 관리를 위해 실시간 원격 모니터링 및 개폐 상태 관리 기능을 갖춘 스마트 함체 모니터링 시스템을 사용하고 있으나 CCTV 영상기록의 안전성 확보에는 한계가 있다. 우리가 제안한 시스템은 함체기록을 블록체인에 분산 저장하여 해시값 비교를 통해 위조를 탐지하고 위조된 함체기록을 복구할 수 있다. 또한 관리서버가 수신하는 함체기록의 무결성을 확인할 수 있도록 무결성 검증 API를 제공하여 함체기록의 무결성을 보장한다. 제안 시스템의 효용성을 검증하기 위해 실험을 통해 무결성 검증 정확도와 소요시간을 측정하였다. 실험 결과 함체기록의 무결성(정확도: 100%)을 확인하였고, 검증 소요시간(평균: 73ms)이 모니터링에 영향을 미치지 않을 것으로 확인하였다.

• 한국전산구조공학회논문집
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• 제36권2호
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• pp.121-130
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• 2023

기어의 구조 안정성 및 치물림 성능을 분석하기 위하여 유한요소해석이 널리 사용된다. 본 연구에서는 스퍼 기어의 유한요소 모델링 조건이 해석 결과 및 간소화 효과에 미치는 영향을 분석하였다. 기어 구조 해석의 간소화 방법으로 기어 몸체 및 잇수 간소화, 요소망 생성 방식, 접촉 및 마찰 조건, 해석 조건 등을 선정하였다. 기어의 성능해석 지표로써 1주기의 기어 치물림 사이클 동안의 정전달 오차를 계산하였고, 간소화 지표로써 해석 소요 시간을 측정하였다. 유한요소해석을 통해 치물림 주기에 따른 접촉 응력 분포 및 변화 양상을 확인하였다. 모델링 조건에 따라 최대 전달 오차와 해석 소요 시간에 차이를 확인하고 원인을 분석하였다.

• 한국환경복원기술학회지
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• 제8권4호
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• pp.32-42
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• 2005

To investigate the plants invasion process and dominant species in large-scale cutting slopes, slopes elapsed one year to thirteen years after construction had been selected in five counties. The obtained results are summarized as follows : The species of high appearance frequency were Alnus firma, Arundinella hirta, Miscanthus sinensi var. purpurascens, Erigeron cancdensis, Artemisia princeps var. orientalis, Oenothera odorata, Lactuca raddeana, Lactrca indica var. laciniata, Lespedeza bicolor, Youngia sonchifolia, Populus albaglandulosa, and so on. The biological type of identified vascular plants was $Ch-D_1-R_{5-e}$. In time, plant coverage was increased gradually and average of plant coverage was 1.17% in slopes which elapsed one year, 42.44% after six years, 56.67% after eight years, and 69.17% after ten years. The dominant species in the surveyed slopes were covered with Alnus firma, Artemisia princeps var. orientalis, Erigeron cancdensis, Miscanthus sinensi var. purpurascens, Arundinella hirta, Lactuca raddeana, Oenothera odorata, Boehmeria spicata, Kummerowia striata and Artemisia montana of the 59 species. The conditions of location in large-scale cutting slopes are hard to fix and germinate of seeds, and extend plant roots in the slope soil. Hence, the highly appearance species and dominance species of the area will make plant coverage quick and slope stable.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2000년도 봄 학술발표회 논문집
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• pp.512-519
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• 2000

The discharge capacity of vertical drains installed in the field is reduced with time elapsed after installation due to deformation of drains and clogging effect. Discharge capacity of two types of vertical drains was analysed about three years after installation in the subsoil. Discharge capacity of two types of vertical drains were measured by small, middle, and large scale test apparatus. The results indicate that the discharge capacity of vertical drains after three years operation dramatically decreased compare to the initial discharge capacity.

• 한국대기환경학회:학술대회논문집
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• 한국대기환경학회 2007년도 추계학술대회 논문집
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• pp.301-302
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• 2007

• 한국대기환경학회지
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• 제16권1호
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• pp.1-10
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• 2000

The behavior of aerosos due to gravitational coagulation was studied experimentally and numerically. In experimental study, the geometric mean particel size increased as time elapsed in a vertical tube column, while the size decreased when the tube was set horizontally. The particle size distribution was observed to maintain the lognormal form during the coagulation process. Separately, numerical calculations were performed for studying the aerosol behavior under gravitational and Brownian coagulation using the moment method. By comparing the expeimented results with the numerical predictions, the governing mechanism of the aerosol behavior proved to be gravitational coagulation.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2010년도 춘계 학술대회 제22권1호
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• pp.321-322
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• 2010

본 논문은 국내 재료성능모델 개발을 위하여 새로운 시간경과에 따른 코크리트 강도 발현 모델식을 제안 하고자 한다.

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2002년도 추계학술발표회
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• pp.351-354
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• 2002

In this study, variation of electrochemical parameters and characteristics of lead immobilization due to phosphoric acid injection in soil were studied during electrokinetic remediation of lead contaminated soil. TCLP result showed about 100% of soil was satisfied TCLP regulation criteria. And injected ion from cathode reservoir by ionmigration was proportionate to concentration of phosphoric acid and elapsed time. Therefore, when removal is infeasible or not cost-effective, in situ immobilization method would be more effective.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1996년도 봄 학술발표회 논문집
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• pp.402-407
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• 1996

In this paper, we described the basic elements(flowability, fillingability, elapsed time, pumpability, no-vibrating effects, and etc.) required for the application and quality control of the super flowing concrete (SFC) in construction site. Also, after investigating characteristics of SFC through various experiments, SFC were placed in the reaction wall of large scale structural laboratory in Deawoo Insititute of Construction Technology. As the result of this project, the developed SFC showed high flowability and self-filingability good enough for the requirement. Furthermore, quality control and assurance of the no-vibrating concrete in actual site was verified by various testing.