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정영관(Young-guan Jung),김경훈(Kyoung-hoon Kim),김세웅(Se-woong Kim) 한국자동차공학회 2002 한국자동차공학회 지부 학술대회 논문집 Vol.- No.-
Numerical analysis on the atomic and molecular level is necessary as properties of materials are based on the correlation between atoms or molecules. The embedded atom method established on density functional theory was developed as a new means for calculating various properties and phenomena of realistic metal systems. In this study, we had corrected constitutive formulae and parameters, and developed the program on the nickel and the palladium for the purpose of doing Embedded Atom Method analyses on metals. And then we have computed the properties of the nickel and the palladium on the fundamental scale of the atomic structure. As a result, simulated ground state properties, such as the lattice constant, elastics constants and sublimation energy, show good agreement with Daw's simulation data and with experimental data.
정영관(Young Guan Jung),김경훈(Kyoung Hoon Kim),이근진(Keun Jin Lee) 한국수소및신에너지학회 2001 한국수소 및 신에너지학회논문집 Vol.12 No.2
In order to study the relation between expansion of the specimen and the hydrogen absorption rate, thin palladium plates with cold rolling were used. Thin palladium plates were hydrogenated in the 0.1mol H₂SO₄ electrolyte by electrochemical method. The expansion behavior on hydrogen absorbing can be obtained by X-ray diffraction analysis and by micrometer measurement. It is noted that the expansion rate of Palladium specimens in thickness direction is larger than in length and width direction. The lattice constants increase quickly with increasing hydrogen absorbing rate up to 0.5, but above the rate they keep constant. Also the clues for plastic deformation, such as slip lines and voids, were observed in abundantly even though the plates were hydrogenated once.
디젤기관에 대한 앳킨슨사이클 구성과 사이클의 열역학적 해석에 관한 연구
김철수,정영관,장태익,Kim Chul Soo,Jung Young Guan,Jang Tae lk 한국마린엔지니어링학회 2005 한국마린엔지니어링학회지 Vol.29 No.2
The present study composed a diesel-atkinson cycle of high expansion as a method of achieving high efficiency in diesel cycle engines. It also interpreted the cycle engine thermodynamically analysis to determine the possibility of the improvement of thermal efficiency and clarified the characteristics of several factors . According to the result of theoretical analysis, heat efficiency was highest when expansion-compression ratio Reど:1. In addition. diesel engines with high apparent compression ratio had higher expansion-compression ratio than otto engines and consequently their effect of high expansion was high. which in turn enhanced thermal efficiency. When the atkinson cycle was implemented in a real diesel engine by applying the miller cycle through the variation of the closing time of the intake valve, the effective compression ratio and the quantify of intake air decreased and as a result, the effect of high expansion was not observed. Accordingly. the atkinson cycle can be implemented when the quantity of intake air is compensated by supercharge and the effective compression ratio is maintained at its initial level through the reduction of the clearance volume. In this case. heat efficiency increased by $4.1\%$ at the same expansion-compression ratio when the apparent compression ratio was 20 and the fuel cut off ratio was 2. As explained above, when the atkinson cycle was used for diesel cycle. heat efficiency was improved. In order to realize high expansion through retarding the intake value closing time, the engine needs to be equipped with variable valve timing equipment, variable compression ratio equipment and supercharged Pressure equipment. Then a diesel-atkinson cycle engine is realized.