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프리캐스트 콘크리트 세그먼트의 합성섬유 보강재 적용에 따른 구조적 성능 평가
이호성,김창용,이승원,김승준,이경진,Lee, Hoseong,Kim, Changyong,Lee, Sean S.,Kim, Seungjun,Lee, Kyeongjin 한국터널지하공간학회 2018 한국터널지하공간학회논문집 Vol.20 No.2
쉴드TBM 터널의 프리캐스트 콘크리트 세그먼트 라이닝의 보강재로 철근이 주로 사용되어 왔으나, 철근 보강량을 줄이기 위하여 섬유보강재를 적용하는 연구가 진행되어 오고 있다. 세계적으로 터널 시공성을 향상시키기 위하여 강섬유보강재를 적용한 연구와 시공이 진행되어 왔으나, 터널 라이닝 방수막에 대한 펀칭, 자체 부식에 의한 내구성 및 미관상의 문제로 인하여 이에 대한 적용이 국내에서는 미뤄지고 있는 실정이며, 이에 대한 대책으로 합성섬유가 강섬유의 대체제로 주목 받고 있다. 이 연구에서는 섬유(강섬유, 합성섬유) 보강재를 사용한 프리캐스트 콘크리트 세그먼트의 파괴시험을 통하여 성능을 분석하여 현장에서의 적용 가능성을 평가하였다. 그 결과 강섬유와 합성섬유의 조합이나 합성섬유의 혼입량에 따라 보조철근의 대체가 가능한 것으로 분석되었다. Steel bars have been widely used as the primary reinforcement for Precast Segmental Concrete Lining for TBM Tunnels. Previously, studies have been carried out to gauge the potential for steel fiber reinforcement to replace the use of steel bar reinforcements in the segmental lining to reduce the amount of the steel bar reinforcement. Steel fiber reinforcements have been investigated and widely applied to SFRC TBM linings to improve the constructability of SFRC TBM linings worldwide. However, the steel fiber reinforcement often caused punctures to the water membranes inside tunnel lining and had long-term durability deterioration issues caused by steel corrosion, as well as cosmetic problems. Therefore, this paper sought to gauge the potential of synthetic fiber reinforcements, which have proven to be very attractive substitutes for steel fiber reinforcements. This study analyzed the performance of both steel and synthetic fiber reinforcements in segmental linings and evaluated the applicability of the fiber reinforcements to the TBM Precast Concrete Segmental Linings of TBM tunnels. As a conclusion, this study demonstrates that the potential use of steel and synthetic fibers in various combination, can substitute the rebar reinforcement in the concrete mix for segmental concrete linings.
연료전지 자동차 스택 냉각 시스템 성능 향상을 위한 해석적 연구
이호성(Hoseong Lee),원종필(Jongphil Won),조중원(Choongwon Cho),이동혁(Donghyuk Lee),박용선(Yongsun Park),김성균(Sungkyun Kim) 한국자동차공학회 2009 한국자동차공학회 학술대회 및 전시회 Vol.2009 No.11
Analyses in stack cooling system for fuel cell electric vehicle(FCEV) has been performed. The amount of heat discharge for FCEV stack cooling system is approximately up to 2 times more than that for conventional internal combustion vehicle due to low temperature difference between coolant inlet and air inlet. This paper investigated stack cooling performance of FCEV by means of 3D thermal flow analytic software, UH3D, at the severe condition for cooling, such as high ambient temperature, low vehicle speed and up-hill mode. As a result of 3D simulation, it was estimated that applied FCEV stack cooling system required more heat rejection to cope with this simulation. To improve cooling capacity, several case studies, such as cooling module layout(up and down), a gap between a condenser and stack radiator, distance between stack radiator and fan, and stack location variation, were simulated. Consequently, it was found that cooling performance was improved by max. 1.2% for 20㎜ gap between a condenser and stack radiator. Cooling performance was influenced by the distance between cooling module and stack and BOP components because the recirculation of heated air through cooling module blocked the fresh air, so that cooling air temperature rised. Hence, when the case of no-stack behind cooling module was analyzed, cooling performance was elevated by about 4% because of no-recirculation and more cooling air flow rate. This simulation for no-stack case was considered by the current FCEV developing trend, which fuel cell system was located at under-floor.
연료전지 스택 배열을 활용한 CO₂ 난방 시스템 배열열교환기 성능 특성에 관한 실험적 연구
이호성(Hoseong Lee),원종필(Jongphil Won),조중원(Choongwon Cho),임택규(Taekkyu Lim),모지환(Jihwan Mo),김용찬(Yongchan Kim) 한국자동차공학회 2010 한국자동차공학회 학술대회 및 전시회 Vol.2010 No.11
The aim of this study is to investigate the performance characteristics of CO₂ Heat Pump(H/P) system using the stack cooling coolant / refrigerant heat exchanger for fuel cell electric vehicles(FCEV). The present heating system for FCEV uses PTC heater, which results in lower fuel efficiency and reduction of driving range. To cope with heating performance improvement without additional power consumption, one of possible methods is to use stack coolant heat for FCEV. Due to high pressure and temperature operating condition for CO₂, CO₂ heat pump has been concerned that it seems to cover heating capacity with the similar capacity of engine coolant heating system. Furthermore, CO₂ heating system is free of environmental regulations for a vehicle refrigerant. In this study, experiments to analyze heating performance characteristics using the coolant / refrigerant heat exchanger have been done with various operating conditions, which are likely to match the actual vehicle’s driving conditions under cold ambient conditions, such as variation of coolant flow rate and interior air temperature. Experimental results show that the heating capacity has Max. 9.5 ㎾ @ coolant temperature 60℃, interior air outlet temperature is up to 45℃ @ ambient temperature -20℃, and the capacity of the coolant / refrigerant heat exchanger is 6.5 ㎾ @ coolant temperature 60℃. From various experimental results, optimal coolant flow rate to have optimum heating performance seems to exist under a certain ambient temperature(5.0 LPM@ ambient temperature -20℃)