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선박 내 폐열 회수 시스템 구성을 고려한 유기 랭킨 사이클의 열역학적 분석
이동길(Dongkil Lee),진정근(Jungkun Jin),이호기(Hoki Lee),박건일(Gunil Park) 대한기계학회 2012 대한기계학회 춘추학술대회 Vol.2012 No.11
The present work focuses on the heat transfer loop of Organic Rankine Cycle - Waste Heat Recovery System (ORC-WHRS) for the vessel. The heat transfer loops were evaluated based on the power output of thermal cycle. Performances of ORC were calculated at the different temperature conditions of thermal loop. Calculated results were compared in terms of cycle and system efficiency. The result shows additional electricity of Maximum. 660㎾e can be produced by using ORC-WHRS, and the system has 9~13% of cycle efficiency depends on the heat transfer loop design and pinch condition of heat exchanger. In this work shows, ORC-WHRS can produce 60~73% of required electricity of Suez-max COT at the normal operation running condition and this lead to fuel saving effect.
선박 주기관 폐열 회수를 위한 유기 랭킨 사이클 시스템 최적화
이동길(Dongkil Lee),이호기(Hoki Lee),박건일(Gunil Park),최재웅(Jaewoong Choi) 대한기계학회 2013 대한기계학회 춘추학술대회 Vol.2013 No.12
Addition of evaporator and preheater were studied to maximize output power of organic rankine cycle as a waste heat recovery system of the marine diesel engine. Exhaust gas, scavenge air and jacket cooling water were considered as possible heat sources to be recovered. Dual loop system which has multiple heat transfer loops for each waste heat source shows better performance than the single loop system which has only one heat transfer loop. By changing ORC evaporator and preheater, the output of ORC increased by 6~27%.
선박 열원 열량 변동에 따른 Dual turbine 유기 랭킨 사이클 시스템의 성능변화 고찰
이동길(Dongkil Lee),이호기(Hoki Lee),박건일(Gunil Park),최재웅(Jaewoong Choi) 대한기계학회 2014 대한기계학회 춘추학술대회 Vol.2014 No.4-3
Dual turbine organic rankine cycle were studied to maximize power output of waste heat recovery system for the marine diesel engine. In this study, two turbines were parallel applied to organic rankine cycle to have better response for multiple heat sources and its variation amount. The results of this work shows that dual turbine organic rankine cycle system has better load following power output response than single turbine organic rankine cycle with variation of heat source condition. The corresponding organic rankine cycle system were simulated and verified through experiments.
IVN 시스템을 위한 IEEE 1451 기반 중복 모듈
김현희(Hyunhee Kim),김용옥(Yongok Kim),이호기(Hoki Lee),이경창(Kyungchang Lee),이석(Suk Lee) 한국자동차공학회 2009 한국자동차공학회 부문종합 학술대회 Vol.2009 No.4
Drive-by-wire systems consist of bus systems, microprocessors, electrical actuators, and sensors. Replacing rigid mechanical components with dynamically configurable electronic elements triggers an almost organic, systemwide level of integration. That is, for their design safety, integration methods including reliability and fault-tolerance are required. In general, the fault-tolerance function is realized by redundancy of the communication module. In this paper, we introduced the concept and design methodology of an IEEE 1451 based dual redundant module as one method for realization of the redundancy in CAN network.
AlN/PSS Template 위에 HVPE로 성장한 GaN 막의 특성
손호기,이영진,이미재,김진호,전대우,황종희,이혜용,Son, Hoki,Lee, YoungJin,Lee, Mijai,Kim, Jin-Ho,Jeon, Dae-Woo,Hwang, Jonghee,Lee, Hae-Yong 한국전기전자재료학회 2016 전기전자재료학회논문지 Vol.29 No.6
In this paper, GaN film was grown on AlN/PSS by hydride vapor phase epitaxy compared with GaN on planar sapphire. Thin AlN layer for buffer layer was deposited on patterned sapphire substrate (PSS) by metal organic chemical vapor deposition. Surface roughness of GaN/AlN on PSS was remarkably decreased from 28.31 to 5.53 nm. Transmittance of GaN/AlN grown on PSS was lower than that of planar sapphire at entire range. XRD spectra of GaN/AlN grown on PSS corresponded the wurzite structure and c-axis oriented. The full width at half maximum (FWHM) values of ${\omega}$-scan X-ray rocking curve (XRC) for GaN/AlN grown on PSS were 196 and 208 arcsec for symmetric (0 0 2) and asymmetric (1 0 2), respectively. FWHM of GaN on AlN/PSS was improved more than 50% because of lateral overgrowth and AlN buffer effect.
FS-GaN을 열산화하여 제작된 Beta-Ga<sub>2</sub>O<sub>3</sub> 박막의 특성
손호기,이영진,이미재,김진호,전대우,황종희,이혜용,Son, Hoki,Lee, YoungJin,Lee, Mijai,Kim, Jin-Ho,Jeon, Dae-Woo,Hwang, Jonghee,Lee, Hae-Yong 한국전기전자재료학회 2017 전기전자재료학회논문지 Vol.30 No.7
In this paper, we discuss ${\beta}-Ga_2O_3$ thin films that have been grown on freestanding GaN (FS-GaN) using furnace oxidation. A GaN template was grown by horizontalhydride vapor phase epitaxy (HVPE), and FS-GaN was fabricated using the laser lift off (LLO) system. To obtain ${\beta}-Ga_2O_3$ thin film, FS-GaN was oxidized at $900{\sim}1,100^{\circ}C$. Surface and cross-section of prepared ${\beta}-Ga_2O_3$ thin films were observed by field emission scanning electron microscopy (FE-SEM). The single crystal FS-GaNs were changed to poly-crystal ${\beta}-Ga_2O_3$. The oxidized ${\beta}-Ga_2O_3$ thin film at $1,100^{\circ}C$ was peel off from FS-GaN. Next, oxidation of FS-GaNwas investigated for 0.5~12 hours with variation of the oxidation time. The thicknesses of ${\beta}-Ga_2O_3$ thin films were measured from 100 nm to 1,200 nm. Moreover, the 2-theta XRD result indicated that (-201), (-402), and (-603) peaks were confirmed. The intensity of peaks was increased with increased oxidation time. The ${\beta}-Ga_2O_3$ thin film was generated to oxidize FS-GaN.
N-polar면의 선택적 에칭 방법을 통한 Free-standing GaN 기판의 Bowing 제어
김진원,손호기,임태영,이미재,김진호,이영진,전대우,황종희,이혜용,윤대호,Gim, Jinwon,Son, Hoki,Lim, Tea-Young,Lee, Mijai,Kim, Jin-Ho,Lee, Young Jin,Jeon, Dae-Woo,Hwang, Jonghee,Lee, Hae-Yong,Yoon, Dae-Ho 한국전기전자재료학회 2016 전기전자재료학회논문지 Vol.29 No.1
In this paper, we report that selective etching on N-polar face by EC (electro-chemical)-etching effect on the reduction of bowing and strain of FS (free-standing)-GaN substrates. We applied the EC-etching to concave and convex type of FS-GaN substrates. After the EC-etching for FS-GaN, nano porous structure was formed on N-polar face of concave and convex type of FS-GaN. Consequently, the bowing in the convex type of FS-GaN substrate was decreased but the bowing in the concave type of FS-GaN substrate was increased. Furthermore, the FWHM (full width at half maximum) of (1 0 2) reflection for the convex type of FS-GaN was significantly decreased from 601 to 259 arcsec. In the case, we confirmed that the EC-etching method was very effective to reduce the bowing in the convex type of FS-GaN and the compressive stress in N-polar face of convex type of FS-GaN was fully released by Raman measurement.
Stress Distribution of Buried Concrete Pipe Under Various Environmental Conditions
Lee, Janggeun,Kang, Jae Mo,Ban, Hoki,Moon, Changyeul Korean Geo-Environmental Society 2016 한국지반환경공학회논문집 Vol.17 No.12
There are numerous factors that affect stress distribution in a buried pipe, such as the shape, size, and stiffness of the pipe, its burial depth, and the stiffness of the surrounding soil. In addition, the pipe can benefit from the soil arching effect to some extent, through which the overburden and surcharge pressure at the crown can be carried by the adjacent soil. As a result, the buried pipe needs to support only a portion of the load that is not transferred to the adjacent soil. This paper presents numerical efforts to investigate the stress distribution in the buried concrete pipe under various environmental conditions. To that end, a nonlinear elasto-plastic model for backfill materials was implemented into finite element software by a user-defined subroutine (user material, or UMAT) to more precisely analyze the soil behavior surrounding a buried concrete pipe subjected to surface loading. In addition, three different backfill materials with a native soil were selected to examine the material-specific stress distribution in pipe. The environmental conditions considering in this study the loading effect and void effects were investigated using finite element method. The simulation results provide information on how the pressures are redistributed, and how the buried concrete pipe behaves under various environmental conditions.
Stress Distribution of Buried Concrete Pipe Under Various Environmental Conditions
Janggeun Lee,Jae Mo Kang,Hoki Ban,Changyeul Moon 한국지반환경공학회 2016 한국지반환경공학회논문집 Vol.17 No.12
There are numerous factors that affect stress distribution in a buried pipe, such as the shape, size, and stiffness of the pipe, its burial depth, and the stiffness of the surrounding soil. In addition, the pipe can benefit from the soil arching effect to some extent, through which the overburden and surcharge pressure at the crown can be carried by the adjacent soil. As a result, the buried pipe needs to support only a portion of the load that is not transferred to the adjacent soil. This paper presents numerical efforts to investigate the stress distribution in the buried concrete pipe under various environmental conditions. To that end, a nonlinear elasto-plastic model for backfill materials was implemented into finite element software by a user-defined subroutine (user material, or UMAT) to more precisely analyze the soil behavior surrounding a buried concrete pipe subjected to surface loading. In addition, three different backfill materials with a native soil were selected to examine the material-specific stress distribution in pipe. The environmental conditions considering in this study the loading effect and void effects were investigated using finite element method. The simulation results provide information on how the pressures are redistributed, and how the buried concrete pipe behaves under various environmental conditions.