Failure with Strain Localization of Aluminum Alloy 7075 Sheets at Elevated Temperature and its Application to Two-Step Hybrid Forming

Jong‑Hwa Hong,Hyunki Kim,Wonjae Kim,Yong‑Nam Kwon,Daeyong Kim 대한금속·재료학회 2022 METALS AND MATERIALS International Vol.28 No.4

In this work, the onset of failure induced by severe strain at elevated temperature was numerically estimated with crossformedempirical hardening law describing material softening. The hardening law can replicate the rate-sensitive behaviorof aluminum alloy 7075 sheets (thickness of 2.0 mm) with initial hardening and progressive material deterioration causedby dynamic recrystallization, dynamic recovery, and micro-void development. The characterized material was applied to thetwo-step hybrid forming process consisting of a drawing at 400 °C followed by a pneumatic forming at 470 °C to produce ashock absorber housing with an extremely complex shape. The user-defined subroutine codes, VUMAT (ABAQUS/Explicit)and UMAT (ABAQUS/Standard), were sequentially utilized for the drawing and the pneumatic forming, respectively. Theidentified hardening parameters based on uniaxial tensile tests were validated by simulating the two-step hybrid formingprocess and compared with the conventional Voce type law (converging function) and the combined Swift-Voce type law(ever-increasing function) since they play a key role in accurately predicting the onset of failure induced by severe strainlocalization. Finally, simulation results are reasonably well matched with experiments in terms of the moment of failureoccurrence, failure location, final blank shape, and thickness distribution.

CD34+ 조혈 모세포 이식 2례

김정아,정현식,김원석,윤성수,이홍기,박찬형,박성규,김동욱,이종욱,한치화,민우성,김춘추,김동집 대한조혈모세포이식학회 1996 대한조혈모세포이식학회지 Vol.1 No.1

Background: In most solid tumors, the CD34 antigen has not been detected, so positive selection of CD34+ cells may reduce tumor cell contamination and the CD34+ cells are capable of reconstituting hematopoiesis. We tried CD34+ cell transplantation in two patients. Method: CD34+ cells from chemotherapy + G-CSF mobilized PBPCs or bone marrow were positively selected with an avidin-biotin immunoadsorption column (CEPRATE SC system). Case 1. One course of chemotherapy using cyclophosphamide(200㎎/㎡) and etoposide (4.2g/㎡), combined with G-CSF(5㎍/㎏) S.C. was used in a relapsed lymphoma patient. This patient responded to the induction chemotherapy. CD34+ cells from harvested bone marrow were selected by the CellPro immunoadsorption column. The total number of mononuclear cells loaded onto the CellPro was 2.4×10^(8)/㎏, with 1.1% CD34+ cells. After column separation, the total number of positively selected cells was 5.16×10^(6)/㎏. The number of CFU-GM was 76.8×10⁴/㎏. This patient was treated with melphalan (140㎎/㎡) and TBI (1200cGy) and the positively selected CD34+ cells were infused. The time to neutrophil recovery greater than 0.5×10^(9)/L was 19 days and the time to platelet recovery greater than 50×10^(9)/L was 21 days. Case 2. Two courses of mobilizing chemotherapy were given 4 weeks apart using taxol(210㎎/m2) and adriamycin(60㎎/m2), combined with G-CSF(5㎍/㎏) S.C. in a breast cancer patients with 7 axillary node metastasis. CD34+ cells from each single leukapheresis product were selected by the CellPro immunoadsorption column. In the first collection, the total number of nucleated cells was 4.4×10^(8)/kg, with 0.42% CD34+ cells. In the second collection, the total number of nucleated cell was 2.8× 10^(8)/㎏ with 0.43% CD34+ cells. After colum separation, the total numbers of collected cells were 4.0×106/kg and 4.8×10^(6)/kg, the total number of CD34+ cells were 1.2×10^(6)/㎏ and 0.82×10^(6)/㎏. Colonogenic assays of positively selected CD34+ cells gave rise to myeloid erythroid, and multilineage colonies, with a median of 190 CFU-GM, 190 BFU-E, and 164 CFU-GEMM per 1×10³ adsorbed cells, respectively. High-dose chemotherapy with cumulative doses of 40mg/㎡ mitoxantrone, 750mg/㎡ thioptepa, and 1000mg/㎡ carboplatin was administered. Positively selected CD34+ cells were rapidly infused 24 hours after the end of high-dose chemotherapy. The time to neutrophil recovery greater than 0.5×10^(9)/L was 16 days and the time to platelet recovery greater than 50×10^(9)/L was 20 days.

Science and Marxism

Kim, Jong Hwa 덕성여자대학교 사회과학연구소 2004 사회과학연구 Vol.10 No.-

Scrutiny라는 계간 저널은 1932년에 창설되었는데, Cambridge 대학의 Leavis 등을 중심으로 지식인들의 토론 광장으로서의 역할을 수행하였다. 이 연구는 Scrutiny가 다른 주제와 관심사를 Scrutiny와 그에 대한 비판론자들(마르크스주의자들)의 관점에서 과학과 Marxism에 대한 명제를 중심으로 점검해 보았다. 과학과 마르크스주의 관계에 대한 주제는 Scrutiny에서 핵심적 과제로 다루어 졌는데, Scrutiny와 마르크스주의자들의 충돌은 그 저널이 마르크스주의에 개입하면서 시발되었고, 마르크스주의자들은 Scrutiny를 역사적·이념적 궤도 속으로 몰아넣으면서 비판하였다. 마르크스주의자들은 특히 Scrutiny의 정치적 요소 고려에 대한 소홀함이 여러 측면에서 불균형적 논리전개를 표출하고 현실성을 간과하였다고 지적하였다. Scrutiny는 문화의 중요성을 강조하면서 본질적으로 生의 질을 순전히 물질적 개념으로 접근하는 공리주의에 반대하는 입장이었다. 즉 Leavis 등 Scrutiny 편집자들은 생의 질을 논하는데 있어서 물질적 측면과 정신적 측면을 포괄적으로 고려하지 않으면 의미가 없다고 주장하였다. 한걸음 더 나아가, Scrutiny가 중시하는 문화란 사회변혁과 산업화로 파괴된다고 봄으로써 분명히 과학과 실용주의적 요소를 결여하게 되었고 결과적으로는 마르크스주의자들의 Scrutiny에 대한 비판도 여기에 초점이 맞추어져 있다. 생각건대 Scrutiny의 정치·사회적 문제에 대한 문화적·도덕적 관행설정으로 Scrutiny가 문화적 엘리트주의에 빠져 문화적 편중접근이라는 비난을 면하기 어렵지만, 도덕적 기준에서 보면 깊이 있게 과학과 마르크스주의를 통찰한 점은 높이 평가 되어야 할 것으로 보여진다.

해도 정보를 이용한 선박의 최적 항로 생성

김민규(Min-Kyu Kim),김종화(Jong-Hwa Kim),양현(Hyun Yang) 한국항해항만학회 2022 한국항해항만학회 학술대회논문집 Vol.2022 No.2

Min-Kyu Kim*․Jong-Hwa Kim**․†최근 자율 운항 선박에 대한 관심이 높아지고 있다. 특히, MUNIN (Maritime Unmanned Navigation through Intelligence in Networks) 프로젝트를 계기로 자율 운항 선박에 대한 개발과 연구가 활발히 진행되고 있다. 또한 국제해사기구 IMO는 자율 운항 선박 시대에대응하기 위해 자율 선박을 MASS (Maritime Autonomous Surface Ship)라 정의하고 선박 자율화 정도에 따라 4단계 등급을 제시하고 있다. 완전한 자율 운항 선박에 대한 요구조건을 만족하기 위해서는 항로 결정과 제어기술이 필수적이다. 본 연구에서는 여러 가지 기술 중 선박의최적경로를 생성하는 기법을 다룬다. 기존에 최적항로를 생성하기 위한 방법으로는   , Dijkstra와 같은 알고리즘들이 주로 사용되었다. 그러나 이와 같은 알고리즘은 섬이나 육지에 대한 충돌 회피는 고려하고 있지만 수심 및 연안 선박에 대한 규정들은 고려하지 않고 있어실제로 적용하기에는 한계점이 있다. 따라서 본 연구에서는 안전을 위해 선박의 선저 여유 수심과, 해도에 규정되어 있는 선박 운항에 대한여러 규정들을 반영하여 최적 항로를 생성하고자 한다. 최적 항로를 생성하기 위한 알고리즘으로는 강화학습 기반의 Q-learning 알고리즘을적용하였다.

6-Dimethylaminopurine 및 Cycloheximide의 처리가 돼지난포란의 단위발생에 미치는 영향

김종화,박병권,한만희,이규승 충남대학교 농업과학연구소 2007 농업과학연구 Vol.34 No.1

This study is aimed at finding an optimum density for 6-Dimethylaminopurine (6-DMAP) and cycloheximide which have an effect on the revitalization of porcine oocytes. The results were summarized as follows: 1. When 6-DMAP was treated with 2 mM for 2 hours. It showed a significantly (P<0.05) different high result in activation rate, cleavage rate and blastocyst growth rate of 51.2%, 52.7% and 25.2% respectively. 2. When Cycloheximide was treated with 5 ug/ml for 6 hours, It showed a significantly (P <0.05) different high result in activation rate, cleavage rate and blastocyst growth rate of 47.7%, 46.8%, and 27.3% respectively. 3. When it was cultured in the culture medium, NCSU, for 7 days after inducing activation with 6-DMAP and cycloheximide, it showed no differences in the number of inner cell mass (ICM) and total cell of blastocysts. To conclude, it has been examined for porcine oocytes to be suitable when 6-DMAP was treated with 2 mM for 2 hours, Cycloheximide with 5 ug/ml for 6 hours.

저신장 어린이에서 Insulin 자극에 대한 성장호르몬과 Cortisol의 반응

김화인,오재화,최두영,김종덕 대한소아내분비학회 1999 Annals of Pediatirc Endocrinology & Metabolism Vol.4 No.2

Probiotics의 최근연구동향

김진욱,정종근,주치언,이재화 신라대학교 자연과학연구소 2005 自然科學論文集 Vol.14 No.-

Probiotics는 "장내균종을 개선시켜 줌으로써 숙주동물에게 유익한 영향을 주는 것", "사람 또는 동물 장내 미생물의 균형을 개선시켜 숙주에 효과를 주는 살아있는 미생물 단독 또는 혼합배양물"이라는 의미의 용어이다. Probiotics의 조건에는 효능성, 안전성, 안정성, 분리성의 4가지 조건을 만족시켜야 하며, 식품의 상품성 향상, 면역증강, 유해효소의 합성 억제, 유당 불내증 개선, 장내 유해균의 증식 억제, 장내 균총의 정상화 등 다양한 효능을 가지고 있다. 이런 다양한 효능을 가진 probiotics는 건강식품 및 의료용의 소재, 화장용 소재, 사료 첨가제, 생 백신 개발 재료, 천연 항균물질 생산 등 다양한 곳에 응용되어 사용이 가능하다. Probiotics are living non-pathogenic micro-organisms, which as food ingredients also beneficially affect host's health. These non-pathogenic micro-organisms may be lactic acid bacteria, such as lactobacilli, lactococci, and bifidobacteria, or yeasts, such as Saccharomyces cerevisiae subspp. boulardii, or bacillus, such as B. subtilis, B. natto, B. licheniformis. Probiotics were originally used to influence both animal and human health through intestinal microbiota alterations. At present, the specific live microbial food ingredients and their effects on human health are studied both within food matrices and as single or mixed culture preparations. Probiotics such as lactobacilli have been reported to effect positively, gastrointestinal disorders such as diarrhoea (rotavirus-associated and antibiotic -associated), inflammatory bowel disease, pouchitis, irritable bowel syndrome, colorectal cancer, lactose absorption, Helicobacter pylori infection and constipation and are increasingly used as a treatment modality. Basic and clinical research should thus be associated to meet the enthusiasm that patients show for a therapeutical approach that they feel to be safer than most drugs currently proposed to them.

2005학년도 신입생 실태조사

김두화,박종필,박정환 濟州大學校 職業能力開發院 2006 學生生活硏究 Vol.27 No.-

The purpose of the survey is to collect basic data on freshmen in 2005 and to understand students' general matters for make substantial measures on academic affairs in our university, For the purpose of the study, the researcher composed a questionnaire(on students' current conditions, values, university life etc) based on earlier surveys and distributed and collected during the orientation period of . 1802 students are answered the questionnaire and the results of the survey suggest that : 1. It needs to increase the opportunities to take career guidance and counseling. When asked main concerns, most students answered that their main concern or interest is 'getting a job' or 'entering a school of higher grade' Also they answered that the reason to enter the university is to find more prospective Job and want to take coundeling service on 'getting a job' or 'entering a school of higher grade'. Thus, to meet their needs, it needs to increase the opportunity to take psychological test, career guidance and counseling with close cooperation with other related university offices. 2. It needs to increase the opportunities of oversea training for students. Most of the students had a positive image on the oversea training and these experience is directly related with students' competitiveness in job markets. Thus, it needs to take supportive steps to collect sufficient fund for the oversea training. 3. It needs to support students who want to be a public official or teacher. Most of the students preferred to be a public officer or teachers, so that the university should take some measures to support these students. 4. The current strategy for university advertisement should be reappraised. Cheju National University holds several expositions for highschool graduates to advertise the university, but it revealed that these expositions are not effective because many students replied that they found useful information through university's homepage, highschool teachers. Thus, the university should change current strategy based on exposition for highschool students and make more effective plans for advertising departments and the university. 5. The university should take some measures to increase students' pride which is related to the university. 52.8% of the students replied that they are proud of the university, but 43.4% of the students replied that they are not. Finally, the university collect data only from freshmen, and results from these data analysis have some limitation to understand all students in the university. Thus, to get more accurate information and to make more effective decision making, the survey should extended to all students in the university.

열교환기의 핀과 튜브 접촉부에서의 응력해석

김종화,박명균,양진승 명지대학교 산업기술연구소 2001 産業技術硏究所論文集 Vol.20 No.-

Usually the contact between fin collar and tube surface for fin-tube heat exchanger is secured by mechanical expansion of the tubes. The objective of the present study is to analyzed the stress distribution around the contact region between the tube and fin. Through this numerical analysis, the thermal contact resistance between them could be understood well so that the performance of heat exchanger could be improved.

SIPT의 內部抵抗의 測定法에 관한 硏究

金鍾和 木浦大學校 工業技術硏究所 1996 工業技術硏究誌 Vol.6 No.-

In this paper, the measurement methods of the source resistance rs and drain resistance rd that is necessary to the calculation of the reduction rate of shot noise so as to analyze the noise factors of SIT is investigated. The most compatible measurement method of the source and drain resistance is using the input admittance of source follower, and the source and drain resistance cna be induced by the input admittance Y1p=(1+Rip)+jωCip of SIT.