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차윤정,박진영,장정환,김성환,김권천,조현진,민영돈 조선대학교 2001 The Medical Journal of Chosun University Vol.26 No.1
Background and Objectives: Gastric cancer is still the leading cause of cancer death in Korea, and surgery remains the only method of treatment that offers the potential for a cure. Purpose: The aims of this study are to examine the outcome of the patients with gastric adenocarcinoma who underwent curative resection and to identify the prognostic factors leading to improved survival rates in these patients. Materials and Methods: The medical records of 278 patients with gastric adenocarcinoma, treated curatively at the Chosun University Hospital between January 1990 and December 1994, were reviewed retrospectively from January 2000 to March 2000. Follow-up was obtained for 250 patients(89.9%). The survival rates were calculated by the Kaplan-Meier method, and the significance of differences between patient factors(age and sex), tumor factors(location, size, gross type, tumor depth, lymph node metastasis, and stage) and treatment factors(operation method and reconstruction type) were evaluated statistically by the log-rank test. Results: The overall five-year survival probability was 59.6%. There was no survival difference according to age and sex. The 5-year survival rates according to the tumor depth were 97.0% for Tl, 74.5% for T2, 39.6% for T3, and 23.1% for T4(p=0.0000); to the lymph node metastasis were 81,4% for N0, 51.9% for N1, and 21.2% for N2(p=0.0000); to the TNM stage were 96.7% for stage I a, 79.5% for stage I b, 68.8% for stage II, 52.9% for stage III a, 25.9% for stage III b, and 7.5% for stage IV(p=0.0000). Other statistically significant differences were shown in tumor location, size, gross type, operation method, and reconstruction type after subtotal gastrectomy. Conclusion: The most definitive prognostic factors affecting the survival rate of gastric adenocarcinoma were tumor depth, lymph node metastasis, and tumor stage. The keys to successful outcome includes early diagnosis and curative resection with radical lymph node dissection at early stage as possible.
오정국,차용훈,오환섭,박준건,박경식 朝鮮大學校 機械技術硏究所 1998 機械技術硏究 Vol.1 No.1
현재까지 이종마찰압접재의 강도측정은 실험 (7)-(15)에 의해 구해져 왔다. 하지만 최근 이종마찰압접재의 효율성을 인정하여 여러 실용 부품에 응용하려는 연구가 한창 진행중이다. 이종마찰압접재에 대한 저자들(1)-(6)의 기초실험결과 일반적인 단종재와는 상이한 파괴거동(3)이 관찰되었고, 파괴역학적인 관점에서 정성적인 data 확보가 필요하게 되었다. 따라서 본 연구에서는 인장시험시 이종마찰압접재의 접합강도와 미소균열들에 의한 파괴거동을 파괴역학적 관점에서 해석적으로 고찰하여 보고자 경계요소법(BEM ; Boundary Element Method)을 이용하여 접합계면을 포함하는 접합부를 중심으로 계면상의 응력분포와 계면의 중앙에 결함이 균열로써 존재하는 경우의 응력분포와 인장시험시 열영향부에서 관찰된 균열의 모델링을 통한 균열선단에서의 응력해석을 행하였고, 그 결과 얻어진 중요한 내용을 요약하면 다음과 같다. 계면의 중앙에 균열이 존재하는 접합계면의 표면부에서 응력의 특이성이 발생하며 탄성계수의 비가 증가할수록 특이성이 증가함이 관찰되었다. 탄성계수의 비가 일정한 경우 균열의 크기가 변화하여도 계면의 표면부에서 발생하는 특이성은 거의 같은 값을 갖게 되며, 탄성계수의 비가 증가할수록 표면부의 응력 특이성의 크기는 증가한다. 이종마찰압접재의 인장시험시 관찰된 균열을 모델링 하여 해석한 결과 최대 응력 기준으로 살펴볼 때 인접한 균열선단에서의 응력분포는 균열을 합체시키는 방향으로 작용함을 알 수 있다. In this study stress distribution on the interface and stress near tip of the sub-interface crack in the dissimilar friction welded material is analyzed by using of BEM( Boundary Element Method). Stress singularity near surface of model to analyze is observed for various crack length and ratio of elastic modulus. Tensile and shear stress distribution near two neithbor sub-interface crack tips are analyzed. Existance of singularity near surface on the interface is particular situation so that we need to investigate for dissimilar friction welded materials by means of numerical analysis method.
직류전위차법에 의한 피로균열 진전속도 측정시스템의 제작
배성인,차정환,김종섭,최수준 國立 昌原大學校 産業技術硏究所 1995 産技硏論文集 Vol.9 No.-
Automatic fatigue crack length measuring system using DC electrical potential method and the system control program for automatic fatigue testing under random load condition were made in this study. And using these system and control program, fatigue tests were executed under constant and random load condition. As the result, the propagation of crack in random loading can be represented Paris equation and log normal probability function. But, constant and random load test show different crack propagation properties.
류지구,최혁환,차영호,김정헌,조경연 釜慶大學校 1997 釜慶大學校 論文集 Vol.2 No.2
The wide spread of multimedia sysrem deands a large viewing display device which can inform a message to many peoples in open area. This paper is about the design and simulating of a large viewing digital multi-wision control ASIC(Application Specific Integrated Circuit). In this paper. the digital multi-vision ASIC has one channel of imput cideo signal wihich is compliance with CCIR-656 specification and four channels of output video signal which are compliance with CCIR-601 specificarion. It has 2 operating mode. The one is the pass-thro;ugh mode. input vido signal goes to output video signal without any change, and the another one is the expension mode, input video signal is expended by from 2 to 16 times into output video signal. In expension mode. awindow could be programmed and only the input video signal in the window is expended. The 0.6 micron CMOS sEA OF Gate is used to design the ASIC in amount of about 23,000 gates, and it is simulated at 48MHz.
Cha, Du Hwan,Kim, Hye Jeong,Lee, June Key,Kim, Hyun Uk,Kim, Sang Suk,Kim, Jeong Ho TaylorFrancis 2008 Materials and manufacturing processes Vol.23 No.7
<P> This study investigated the following two issues using the design of experiment (DOE): (1) grinding conditions of tungsten carbide (WC) mold to fabricate aspheric glass lenses for the megapixel camera phone module and (2) pressing conditions in the molding process using the mold fabricated under the optimum conditions found by DOE. The optimization of the grinding and the pressing conditions with respect to the surface roughness (Ra) of the ground WC and the form accuracy (PV) of the molded lens, respectively, were ascertained by employing factorial design method. As a result of the analysis of variance (ANOVA) and P-value (significance level), it was verified that the depth of cut in the grinding process and, in case of the pressing, the time of pressing step 2 represent the most significant operative variables that affect the corresponding response variable. The WC mold was fabricated under the optimum condition found by DOE and it shows a PV of 0.181 µm in aspheric surface. In the optimum condition, percentage transcription ratio is supposed to be 82%.</P>
Effect of temperature on the molding of chalcogenide glass lenses for infrared imaging applications
Cha, Du Hwan,Kim, Hye-Jeong,Park, Heung Su,Hwang, Yeon,Kim, Jeong-Ho,Hong, Jun-Hee,Lee, Kee-Seok The Optical Society 2010 Applied Optics Vol.49 No.9
<P>We examine the effect of temperature on the molding of chalcogenide glass for infrared (IR) lens fabrication and evaluate a molded chalcogenide glass lens. Both the adhesion of the chalcogenide glass to the mold's surface and lens breakage depended on the initial heating temperature and on the molding temperatures in the glass molding process. In addition, the molded chalcogenide glass lens was evaluated based on transcription characteristics of the mold's surface, IR transmittance, and x-ray diffraction patterns. From the analysis results, we verified that the chalcogenide glass lens for IR imaging application could be fabricated by well-controlled temperature conditions.</P>
Ok-Hwan Cha,Mun-Seok Jeong,Clare C. Byeon,Hyun Jeong,Jong-Hun Han,Young-Chul Choi,Kay-Hyeok An,Kyung-Hui Oh,Ki-Kang Kim,Young-Hee Lee 한국탄소학회 2009 Carbon Letters Vol.10 No.1
We propose an evaluation method of the relative content of single-walled carbon nanotubes (SWCNT) in SWCNT soot synthesized by arc discharge using UV-VIS-NIR absorption spectroscopy. In this method, we consider the absorbance of semiconducting and metallic SWCNTs together to calculate the relative content of SWCNTs with respect to a highly purified reference. Our method provides the more reliable and realistic evaluation of SWCNT content with respect to the whole carbonaceous content than the previously reported method.