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정재준(Jae Jun Jung),황원주(Won Ju Hwang),김형진(Hyuong Jin Kim),이태희(Tae Hee Lee) 대한기계학회 2005 대한기계학회 춘추학술대회 Vol.2005 No.5
Metamodels such as response surface model (RSM) and kriging model are used to meet weight minimization of a double-deck train car-body. Weight minimization problem of the double-deck train car-body is required to decide 36 design variables of thicknesses for large aluminum extruded panel while satisfying stress constraints. Therefore, we attempt to reduce the number of design variables by using RSM as a screening process based on orthogonal array design. Global sensitivity and Pareto plot of responses with respect to design variables are employed as screening criterion. After screening design variables, maximum entropy sampling is employed to select additional sample points. We construct kriging model for the mass and maximum stress of a double-deck train car-body with the reduced design variables. Optimization based on kriging model is performed and the merits of this design methodology are discussed.
정재준(Jae Joon Jeong),한동엽(Dong Yub Han),김용일(Yong Il Kim),이재원(Jae Won Lee) 대한공간정보학회 2001 한국공간정보학회지 Vol.9 No.3
Urban growth patterns have occasionally not coincided with planning of the policy makers or urban planners. So it is necessary in the planning step to predict the area to change to urban from rural. In this study, we aim to predict urban growth with cellular automata, a system modeling a dynamic phenomenon. Seoul metropolitan area (SMA) is selected as research area, and urbanized area of SMA has grown rapidly during last 4 decades. Applying the model, urban growth characteristics to date from 1972 are analyzed, and urbanized area maps to the year 2050 are predicted. In this study, the map of urban growth prediction is produced considering urban growth trends to date and some physical factors. And it is considered that the results of the developed model will be used as input data in urban growth prediction systems, which should include more data of socioeconomic and political sides in addition to physical sides.
정재준(Jaejun Jung),이태희(Taehee Lee) 대한기계학회 2001 대한기계학회 춘추학술대회 Vol.2001 No.11
DE(Differential Evolution) algorithm is developed by Ken Price and Rainer Storn who attempt to solve the Chebychev Polynomial fitting Problem. This algorithm is similar to GA(Genetic Algorithm) in populating points, crossing over, and mutating. But It is very simple and easy to use because it introduce vector concept in populating process. Besides its good convergence properties DE is very simple to implement. In this paper, we optimize various test function using DE and GA. on the basis of the results, we compare DE with GA for convergence and accuracy.
DEVELOPMENT AND PRELIMINARY ASSESSMENT OF A THREE-DIMENSIONAL THERMAL HYDRAULICS CODE, CUPID
정재준,윤한영,박익규,HYOUNG KYU CHO,HEEDONG LEE 한국원자력학회 2010 Nuclear Engineering and Technology Vol.42 No.3
For the analysis of transient two-phase flows in nuclear reactor components, a three-dimensional thermal hydraulics code, named CUPID, has been developed. The CUPID code adopts a two-fluid, three-field model for two-phase flows, and the governing equations were solved over unstructured grids, which are very useful for the analysis of flows in complicated geometries. To obtain numerical solutions, the semi-implicit numerical method for the REALP5 code was modified for an application to unstructured grids, and it has been further improved for enhanced accuracy and fast running. For the verification of the CUPID code, a set of conceptual problems and experiments were simulated. This paper presents the flow model, the numerical solution method, and the results of the preliminary assessment.
국소적 간 병소의 평가에서 Gadolinium Chelate와 Mangafodipir Trisodium을 연속적으로 사용하여 얻은 자기공명영상: 영상소견과 안정성에 관한 연구
정재준,김명진,이종태,유형식,Jeong, Jae-Jun,Kim, Myeong-Jin,Lee, Jong-Tae,Yu, Hyeong-Sik 대한영상의학회 2002 대한영상의학회지 Vol.46 No.6
목적:Gd-DTPA와 Mn-DPDP를 연속 주입 후 얻은 MR 영상에서 국소 간 병소의 과혈관성 및 간세포성 여부를 알 수 있는지와 두 조영제를 연속 사용해도 영상진단과 검사과정에 문제가 없는지를 알아보고자 하였다. 대상과 방법:42명(남:여=25:17)을 대상으로 Gd-DTPA 조영 전후와 연속적으로 Mn-DPDP를 주입한 후 T1-강조영상을 얻었으며,각 영상에서 병소의 크기,개수,모양,조영증강 유형등에 대하여 판독하였고,검사와 관련된 부작용에 대하여 기록하였다. 결과:전체 42명(n=94)은 각각 간세포암 15명,전이암 13명,혈관종 9명,간내 담도암 2명,간농양 2명,국소 결절성 과증식 1명이었고,각 병소는 Gd-DTPA 조영 영상과 Gd-DTPA와 Mn-DPDP를 연속 주사 후 촬영한 T1-강조영상에서 모두 잘 관찰되었다.두 조영제를 연속 주사 후 얻은 T1-강조영상에서,간세포암(n=35)중 일부는 간 실질보다 높거나(n=6) 동등한(n=6)신호강도를 보였으나,나머지 23개는 모두 조영증강이 되지 않았다.전이암(n=40)은 38개가 조영증강을 보이지 않았고,나머지 2개는 환형의 조영증강을 보였다.국소 결절성 과증식(n=2)은 모두 균일한 조영증강을 보였고,혈관종(n=13),간내 담도암(n=2),간농양(n=2)은 모두 조영증강되지 않았다.두 조영제를 연속으로 주사하여 경미한 얼굴의 홍조(n=5)외에 결론:Gd-DTPA와 Mn-DPDP를 연속 주입하고 얻은 간의 MR 영상이 기술적으로 문제가 없고 부작용도 없어,국소 결절성 과증식 등의 간세포성 종양과 과혈관성 전이성 간암 같은 비간세포성 종양을 감별하는데 있어서 선택적으로 사용할 수 있는 촬영 방법이라 생각된다. Purpose: To assess the feasibility of sequentially administering Gd-DTPA and Mn-DPDP for the MR imaging of focal hepatic lesions, and to investigate whether the procedures involved led to any adverse effects. Materials and Methods: Forty-two patients (M:F=25:17) with suspected hepatic lesions underwent T1-weighted MR imaging procedures before and after Gd-DTPA enhancement, and after sequential Mn-DPDP administration. Two investigators reviewed the findings in terms of the size, number, morphology, and enhancement patterns of the lesions. Any adverse actions resulting from the procedures were noted. Results: Fifteen patients had hepatocellular carcinoma (HCC, n=35), 13 showed liver metastases (n=40), nine had hemangioma (n=13), two had cholangiocarcinoma (CC, n=2), two had a liver abscess (n=2), and one had focal nodular hyperplasia (FNH, n=2). All focal hepatic lesions were clearly visible, with no difference in conspicuity between T1-weighted images obtained after Gd-DTPA administration and those obtained after Gd-DTPA plus Mn-DPDP administration. After the latter procedure, 12 HCCs showed high or iso- signal intensity to liver parenchyma and 23 showed no contrast enhancement. Thirty-eight liver metastases showed no contrast enhancement, but in two cases ring enhancement was observeed. In both cases of FNH, homogeneous enhancement was noted. No hemangiomas, CCs or abscesses demonstrated contrast enhancement. The only adverse reaction was five instances of facial flushing. Conclusion: Hepatic MR imaging after sequential Gd-DTPA plus Mn-DPDP administration may be selectively useful in differentiating between hepatocellular and non-hepatocellular tumor. No technical difficulties or severe adverse reactions were encountered.
초내열합금 CM247LC의 조직 및 인장특성에 미치는 초기 일방향응고 조건의 영향
정재준,권석환,정의석,조창용,이재현,Jeong, Jae Jun,Kwon, Seok Hwan,Jeong, Eui Seok,Jo, Chang Yong,Lee, Je Hyun 한국주조공학회 2022 한국주조공학회지 Vol.42 No.2
일방향응고 초내열합금 CM247LC의 응고조건에 따른 조직과 기계적 특성을 고찰하기 위해 초기 응고조건을 인위적으로 변화시켜 일방향응고를 진행하였다. 초기 응고 조건은 알루미나 판의 삽입, 접종재의 삽입, Ni foil의 삽입과 냉각판에 직접 주입 등으로 조절하였으며, 이에 따라 초기 결정립의 수의 많은 차이를 보였으며 응고방향과 평행으로 성장하는 결정립의 형태 및 γ' 석출상의 크기 등에서도 많은 차이를 보였다. 냉각속도가 빠른 용탕의 냉각판에 직접 주입한 경우 많은 결정립, 미세한 γ'상 및 γ-γ'공정상 등이 나타났다. 빠른 냉각은 고체/액체 사이의 온도구배를 증가시켜 일방향응고 후 1차 수지상 간격을 미세하게 함으로써 우수한 인장특성을 갖게 하였다.