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CO₂ 자동차 에어컨 시스템의 최적 고압 설정 알고리즘 개발에 관한 연구
이준경(Jun Kyoung Lee),이동혁(Dong Hyuk Lee),이헌균(Heon Kyun Lee),원종필(Jong Phil Won),최규정(Kyu Jung Choi),주필호(Phil Ho Ju),이원석(Won Suk Lee),최동기(Dong Ki Choi) 한국자동차공학회 2006 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
This paper deals with the development of optimum high pressure control algorithm for a transcritical CO₂ mobile air-conditioning system to achieve the maximum COP. The experiments were performed under idle and driving operating conditions. The experimental results demonstrated that the COP of the transcritical CO₂ system is a strong function of the gas cooling pressure. In other words, the COP was increased and then decreased with increase of the high pressure. Therefore the value of high pressure which has maximum COP could be selected. Furthermore, the strong(linear) relation between the optimum high pressure and the gas cooler outlet temperature was revealed, which suggests a simple controller of only one parameter for the transcritical CO₂ cycle.
운전조건 변화가 CO₂ 자동차 에어컨 시스템의 냉방성능에 미치는 영향에 대한 실험적 연구
이준경(Jun Kyoung Lee),이동혁(Dong Hyuk Lee),이헌균(Heon Kyun Lee),원종필(Jong Phil Won),최규정(Kyu Jung Choi),주필호(Phil Ho Ju),이원석(Won Suk Lee),최동기(Dong Ki Choi) 한국자동차공학회 2006 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
This paper deals with the research for the effects of the operating parameters that could be used for a transcritical CO₂ mobile air-conditioning system on the cooling performance. It presents experimental results for the performance characteristics of a CO₂ mobile air conditioning system with various operating conditions such as different gas cooler inlet pressures and frontal air velocities/temperatures passing through the evaporator and the gas cooler. Experimental results show that the cooling capacity was more than 5㎾ and coefficient of performance (COP) was more than 2.1, also. Therefore, we checked that the mobile air-conditioning system using CO₂ has good cooling performance compared to that using HFC-134a.
베이나이트계 후판의 HAZ 미세조직과 저온 충격 인성의 상관관계
이훈(Hun Lee),조성규(Sung Kyu Cho),최우혁(Woo Hyuk Choi),김양곤(Yang Gon Kim),권용재(Yong Jai Kwon),이정구(Jung Gu Lee),신상용(Sang Yong Shin),최동기(Dong Ki Choi) 대한용접·접합학회 2021 대한용접·접합학회지 Vol.39 No.3
In this study, the correlation between HAZ microstructure and low temperature impact toughness of bainitic steel plates was investigated. The Steel with high carbon content and finish cooling temperature has a higher volume fraction and large packet size of granular bainite compared to the steel with low carbon content and finish cooling temperature. The room temperature tensile properties of the two steels are similar, mostly because the microstructure is composed of acicular ferrite having fine grains. On the other hand, the low temperature Charpy absorbed energy of two steels showed a big difference. As the test temperature decreased, the Charpy absorbed energy of the steel with high carbon content and finish cooling temperature decreased more rapidly than the steel with low carbon content and finish cooling temperature. This is due to the high volume fraction of granular bainite and large packet size of granular bainite in the steel with high content and finish cooling temperature. HAZ specimens have a very complex microstructure with a mixture of acicular ferrite, granular bainite, and bainitic ferrite through the rapid cooling process. In the HAZ specimen with high carbon content, more volume fraction of granular bainite + bainitic ferrite was formed, and the packet size of granular bainite + bainitic ferrite was also coarse. Because of this result, the HAZ specimen with high carbon content has low Charpy absorbed energy compared to the HAZ specimen with low carbon content.
해양구조용강 용접부 파괴인성에 미치는 국부취하역(LBZ) 영향
조성규(Sung-Kyu Cho),서준석(Jun-Seok Seo),신상용(Sang-Yong Shin),최동기(Dong-Ki Choi),유동현(Dong-Hyun Ryu) 대한용접·접합학회 2021 대한용접학회 특별강연 및 학술발표대회 개요집 Vol.2021 No.5
최근 극지 해빙 기간과 지역이 확대되고 자원을 탐사하는 기술이 발달함에 따라 극지방에서의 에너지 자원을 개발하려는 경쟁이 심화되고 있다. 극지에서 자원 채굴 및 저장을 위한 해양플랜트는 설치 후 20년 이상의 사용을 필요로 하고 대형화됨에 따라 설계, 엔지니어링, 기자재 및 소재개발 등이 적극적으로 필요하다. 본 발표에서는 소재 관점에서 극지의 -35℃ ~ -60℃ 저온에서 구조적 안정성 및 건전성 확보와 인명/재산피해를 막고 환경오염이 발생하지 않도록, 80mm두께의 모재및 용접부에서 46J이상의 충격인성과 파괴인성(CTOD 0.25mm 이상)을 갖는 강재를 소개하고 용접부 파괴인성에 미치는 영향인자를 재질의 인성적 관점에서 조사하였다. HAZ의 파괴인성을 저하시키는 기구는 용접열사이클에 의한 조대한 결정립을 갖는 국부취화역(LBZ)의 M-A상 및 경한 이차상으로 인해 국소영역에서의 미소한 균열개시와 입내와 입계를 가로지르는 균열전파로 이루어지는 미세파괴기구이다. 따라서 저온에서의 파괴인성을 향상시키기 위해서는 M-A조직의 제어를 이용하여 M-A조직을 억제하는 것과 다층용접에 의한 후행패스의 후열처리 등에 의한 방법으로 최대한 분해하여 HAZ의 인성저하 요인을 제거하는 것이다. 따라서 극저온 환경, 고강도, 극후물화 추세에 따른 구조적 안정성 확보를 위해서는 모재와 용접부의 저온인성과 용접성의 확보가 필요하다. 최적의 합금설계와 TMCP 제조프로세스를 이용하여 결정립을 미세화화여 강도와 인성의 밸런스와 용접 프로세스와 합금설계를 통한 취약한 용접 열영향부(HAZ) 조직제어를 이용하여 국부취화역(LBZ)의 M-A조직의 감소 및 분포를 제어하였다.
Methidathion 중독사에 의한 사후혈액 및 조직중 분포
이종숙(Jong Sook Rhee),이재신(Jae Sin Lee),최동기(Dong Ki Choi),양희진(Hee Jin Yang),이상기(Sang Ki Lee),구기서(Ki Ser Koo),유영찬(Young Chan Yoo) 대한약학회 2002 약학회지 Vol.46 No.2
Methidathion is one of the organophosphorus pesticides commonly used for stamping out hanuul pests in farming areas. This paper presents a fatality due to methidathion intoxication and describes the distribution of methidathion in postmortem blood and tissues obtained at autopsy. Qualitative identification of methidathion was achieved by TLC, GC and GC/MS, and quantitative analysis was performed by GC with thermionic specific detector (TSD). The analytes in postmortem specimens were extracted by liquid- liquid extraction (LLE) with ethylether. After the ethylether layer was evap- orated, the residue was partitioned into hexane and acetonitrile, and the acetonitrile layer was used for analysis. Tissue specimens were homogenized with 4% perchloric acid and applied for LLE. After extraction, the extracts were reconstituted 100μg pyraclofos (IS,100μg/ml in methanol) for GC and GC/MS analysis. On analysis of Postmortem specimens, methidathion was identified and quantitated. The methidathion concentrations were 2.0μl/ml In blood,24.4μg/g in liver 13.9μg/g in lung, 21.8 μg/g in kidney respectively.