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공동주택 실적공사비 산정시 공종별 변동요인에 관한 연구
유용환,이규현,김종원,최인성 한국건축시공학회 2004 한국건축시공학회지 Vol.4 No.4
Construction industry is faced with the problems such as the quickly changeable circumstance and increasing construction companies due to regulation mollification of company registration. In order to overcome these problems, new estimation system based on historical estimation cost is ready to introduce by government step by step. But the time of transition for estimation system causes another problems such as chaos addition to simultaneity of a standard of estimation system and new estimation system, lack of related regulation, accumulation of historical extensive cost data, and adjustment methodology when historical estimation data is applied to next projects. The purpose of this study is to suggest the change factors by activities for estimating historical cost for apartment housing projects. New estimation system is based on historical construction data. For application of this system, the standard adjustment methodology system is necessary. and extensive cost data should be accumulated under an unified construction work classification system. Therefore in this study, according to the construction work classification system, every apartment housing project was classified to 16 work classifications, and 7 major composed items which occupy more than 85% of construction costs are analyzed by detailed activities and by average ratio and maximum ratio each of them. In the result of the study, furniture work, foundation work and masonry work are the works which have big gap of costs between average ration and maximum ratio. In addition to suggestion of change factor by work species, 5 qualified construction specialists are interviewed and change factors in 7 major works are analyzed.
VCM을 이용한 마이크로 조립용 6자유도 정밀 정렬 장치의 설계
유용환,이수훈,송준엽,이창우,하태호,김정재,이문구 한국공작기계학회 2009 한국공작기계학회 춘계학술대회논문집 Vol.2009 No.-
This work will develop a 6-DOF precision aligner with small size and high resolution for assembling the micro parts for a mobile electronics. Here, VCM actuator that is precise and reliable will be applied to this aligner system. Arrangement of actuators will be a symmetrical based on kinematic design. This paper presents combining two modules of mechanism for the 6-DOF precision aligner. The first is a stage which can control XYθ_(z) motion, and the second can control Z motion, in other words, Z tilt motion. According to its specifications, it is expected to satisfy requirement of precision. Test of the first stage was presented to show the resolution and parasitic motion. For the test, PID algorithm was applied for feed-back control system.
구동력을 위한 상부 공기냉각기와 하부 해수열교환기를 최종 열침원으로 하는 피동냉각계통의 예비성능시험
유용환,강경준,박우성,김수형 한국기계기술학회 2022 한국기계기술학회지 Vol.24 No.5
Climatologists have warned rapid climate change of the earth and it will cause a big disaster worldwide. the rapid climate change is mostly due to emission of greenhouse gases. To reduce greenhouse gases, many countries have prepared protocols, agreements, and treaties. IMO(International Maritime Organization) have established the protocol to decrease ship’s greenhouse gases emission and they consider the nuclear power source is an option to replace fossils fuels. Our study focused on elemental technologies related to a nuclear powered ship and, the passive residual heat removal system(PRHRS) is one of topics in our study. As the mandatory of the post Fukushima accident, PRHRS for a nuclear powered ship has been studied. We invented the new concepts of PRHRS which is optimized to a nuclear powered ship. The numerical analysis results indicated that the system is very reasonable. Based on the numerical analysis, an experiential loop was set and we preliminary tested the performance of the system under the reduced scale. The experimental results came with the numerical analysis results well.