複合組織鋼의 摩擦 熔接部의 疲勞破壞特性에 관한 硏究

吳世旭,姜鎬珉,兪在煥,林東哲 東亞大學校 1988 東亞論叢 Vol.25 No.1

This study has been carried out to investigate the characteristics of fatigue crack of welded zone and heat affected zone of friction welded dual phase steel. The results obtained from the experiments are summarized as follows. Microstructure of welded zone is changed to ferrite and pearlite from ferrite and martensite by wel-ding heat. Micro-vickers hardness of welded zone is higher than that of base metal zone and heat affec-ted zone. Micro-vickers hardness of heat affected zone is lower than that of welded zone and microstructure of heat affected zone is changed to fine martensite and ferrite by heating cycle of welding. Fatigue limits of heat affected zone is a little higher than that of welded zone and base metal zone. There are no difference of fatigue limit of base metal zone and welded zone. Fatigue strength of welded zone is similar to that of base metal zone. At high △K region(△K>19MPa·??), fatigue crack propagation velocity of heat affected zone is slower than that of welded zone and base metal zone, and the difference of fatigue crack propagation velocity is smaller than that of high △K region. The crack occurs to the notch in heat affected zone first, but the final fracture surface is the surface of welded zone. It is abvious that heat affected zone of friction welded dual phase steel superior to welded zone and base metal zone in fatigue strength and resistance of fatigue crack propagation. The above mentioned facts are contrary to theory that heat affected zone of general metals is weaker than welded zone and base metal zone.

Morgagni 탈장 : 1례 보고

오연희,이창욱,김승현,이성우,정병욱,이준희,박동일,권영무,신현종 동국대학교 경주대학 1996 東國論集 Vol.15 No.-

Morgagni 탈장은 횡격막의 전내측 부위의 발달이상으로 열공을 통하여 장관이나 대망과 같은 복강내 구조물이 흉곽내로 빠져나가는 드문 질환으로 알려져 있다. 저자들은 호흡곤란을 주소로 내원하여 방사선학적 검사와 수술로 확진된 1례를 보고한다. Morgagni hernia is improperly located abdominal viscera into the thoracic cavity through the foramen of Morgagni which is a congenital defect at the anterornedial portion of diaphragm. We report a case of Morgagni hernia diagnosed by radiologic examination and operation.

Uncoupler를 투여한 흰쥐의 뇌와 간조직의 Superoxide Dismutase에 관한 연구

오창학,이동욱,이희성 중앙대학교 의과대학 의과학연구소 1985 中央醫大誌 Vol.10 No.3

The activities of superoxide dismutases, and the variation of superoxide radicals and hydrogen peroxide contents in the brain and liver tissues, and some of the classic signs of rats administered with either 2, 4-dinitrophenol or arsenate has been investigated. Superoxide dismutase activities were determined either by the method of McCord and Fridovich(1969) or by the method of Crapo et al, (1978). The contents of hydrogen peroxide was determined according to the method of Thruman et al, (1972). The experimental results were summarized as follows; 1. Body weights of animals administered with 2, 4-dinitrophenol and/or arsenate were decreased, but the rectal temperatures of animals treated rose above the normal when compared with those of control group. 2. Formation of superoxide radicals in the tissues of brain and liver of 2, 4-dinitrophenol treated animals was increased to each 1.5 and 1.3 times those of the control group. However, formation of superoxide radicals in the tissues of animals administered with arsenate was not changed in the brain tissues, but significantly decreased in the liver tissues. 3. The contents of hydrogen peroxide was slightly increased in both brain and liver tissues of animals administered with 2, 4-dinitrophenol, but no changes occured in those tissues of animals administered with arsenate. 4. The specific activity of total superoxide dismutase in the brain tissues of animals administered with 2,4-dinitrophenol was enhanced up to 1.7 times that of the control group, but when treated with arsenate, the specific activity was closed to that of the control group. 5. The specific activities of total superoxide dismutase in the liver tissues of animals treated with 2,4-dinitrophenol and/or arsenate were 4.68 and 3.77, respectively. 6. The activities of Mn-superoxide dismutase in the brain and liver tissues of animals treated with 2,4-dinitrophenol was increased to 2.2 and 2.0 times as higher as that of the control group, but no significant change in the activity of Cu,Zn-superoxide dismutase was observed, whereas in the case of arsenate treated animals, no changes in the specific activities of Cu,Zn- and Mn-superoxide dismutase was observed. These results indicated that an uncoupler 2,4-dinitrophenol which may act on all the sites of oxidative phosphorylation caused to increase the superoxide radicals in the cells, and this might occur at State 4. A parallel increment of the formation of superoxide radicals and Mn-superoxide dismutase activities would suggest that the enzyme, especially Mn-superoxide dismutase, must be an important factor to protect the mitochondria from the toxicity by superoxide radicals.

정수장내 약품투입량 자동연산을 위한 신경회로망의 적용 : Focusing of Liquid Coagulant

이동욱,현동수,오석영 大田産業大學校 1996 한밭대학교 논문집 Vol.13 No.1

In this study, the applicability of artificial neural network is analyzed and evaluated to determine the ratio of chemicals dosing in water treatment. To determine the ratio of chemicals dosing for coagulant is very important to the effective control and management of water quality in the water treatment process. It is possible to apply the neural network to the modeling of water treatment process control due to the learning capacities of nonlinearity and the interpolation of input and output data set. The learning process Plays a role of mapping in the relationships between input and output data set, that means the estimation of optimal parameters of the system. So, the more learning continues by rule, the more accurate parameters can be estimated. The neural network model has the function of learning the process which can be trained with the error backpropagation algorithm in two phases. First, the foaming phase permits to fed the best parameters between input and output sets. Second, the adaptive phase use the error backpropagation algorithm in order to learn provided data sets. Turbidity, water temperature, alkalinity, pH and electrical conductivity of raw water which inflows into water treatment plant are used as major input data set of the neural network model. Also, the ratio of chemicals dosing is used as output value of the model. The model can be estimated the ratio of chemicals dosing for each different water quality as input pattern with estimated parameters. The results of this study were compared with the historical observed data by statistical analysis and show the validities in applying to water treatment process control for the determination of chemicals dosing. Based on this study, optimal determination of the ratio of chemicals dosing can be Performed and better water can be produced by using the results with the control of water quality in the water treatment plant.

펌프 관로계에서의 수격현상에 관한 고찰

이동욱,현동수,오석영 大田産業大學校 1996 한밭대학교 논문집 Vol.13 No.1

The tests on the waterhammer were carride out in the pump pipeline system with an air chamber, and the effects of the input variables and the design parameters for the air chamber were investigated by both numerical calculations and experiments. Beacuse the waterhammer problems as a result of pump power failure were the most serious, these situations were carefully studied. Among the input variables used the in the waterhammer analysis, the polytropic esponent, the discharge coefficient of orifice, and the wavespeed had influence on the simulated results in volume on the air chamber increases. the period of waterhammer increasea and the air chamber. Using more smaller orifice in the bypass pipe, the pressure rise was suppressd in some degree and the pressure surge was dissipated more rapidly as passing time. The simulations were fairly good agreement with the measured values until I~2 periods of waterhammer. Not only the maximum and minimum pressures in the pipeline but also its occurring times were reasonably predicted. The computer program developed in this study will be useful to disign the optimum parameters of the air chamber for the real pump pipeline systems.

Buerger병의 HLA항원에 관한 연구

김동일,김수신,오재욱,백세민 大韓成形外科學會 1993 Archives of Plastic Surgery Vol.20 No.3

The purpose of this study is to investigate distribution of the HLA antigens among Korean patients with Buerger's disease and to compare the results of the previous studies. The subjects for this study consisted of 43 operated patients with Buerger's disease who have confirmed by the clinical criteria and angiographic findings and 262 normal korean healthy persons. The method of detection HLA antigens was the microtoxicity test deviced by Terasaki. The observed data are summarized as follows 1. The frequencies of HLA-A2, A3 and A24 were significantly higher among the patients with Bueraer's disease than in the control. 2. The frequencies of HLA-B35, B44, B5l, Bw6O and Bw6l were significantly higher among the patients with Buerger's disease than in the control. 3. By using Bonferoni inequality method, the only Statistically significant HLA antigens were HLA-A2, A24, B35 and B51.

천연두 백신 접종 후 발생된 급성 심근염 1예

박옥성,김종환,이광욱,윤성훈,강동구,이승욱,조상기 朝鮮大學校 附設 醫學硏究所 2006 The Medical Journal of Chosun University Vol.31 No.2

Acute myocarditis complicating coronary vasospasm after smallpox vaccination is very rare complication that can be generally developed within less than 30 days after vaccination. Clinically and biochemically, this disorder is often mimic and highly suggestive of acute myocardial infarction. We report 21 years old man that had a history of a smallpox vaccination 3 weeks ago and prodromal symptoms(fever, malaise etc) a few days ago. hIe visited to our hospital because of abrupt onset of severe substernal chest pain, dyspnea and diaphoresis. At admission, electrocardiography was ST elevation in lead Ⅰ, aVL, V4, V5, and V6. The CK-MB level was 68 U/L, LDH level was 760 U/L, Troponin-Ⅰ was 24.64 ng/㎖, and Troponin-T was positive. 2D-echocardiograpy was normal left ventricular function, Clinically we presumed this disorder as acute myocardial infarction and we promptly performed the coronary angiography and revealed focal spasm in distal left coronary artery territory without critical stenosis in both coronary arteries. We diagnosed this disorder as coronary vasospam complicating acute myocarditis that is different with acute myocardial infarction, and we prescribed nitroglycerin and nifedipine. After discharge, he is now well without any symptoms and has been following up monthly at our outward department for 6 months.

전방 십자 인대 파열에서의 반월상 연골판 파열의 양상

강충남,김종오,김동욱,고영도,유재두,최창호 대한스포츠의학회 1999 대한스포츠의학회지 Vol.17 No.1

Injury to associated structures is expected to worsen the prognosis of ACL tears. Meniscal injuries are well known to coexist in knees with both acute and chronic ACL injuries. However, it is not conclusive whether the likelihood of encountering a repairable meniscal lesion diminishes as the time from injury increases. W e reviewed records of 127 patient receiving an arthroscopically assisted stabilizing procedure for an acute and chronic ACL injury incurred while skiing, soccer, traffic accident to associated meniscal injury. All patient had undergone arthroscopic evaluation. We classified acute injury as injury less than 3 months old at time of surgery, and chronic injury as more than 3 months old. Acute injuries were 88 cases and chronic injuries were 39 cases. In 55 ski-related injuries, 41 knees were acute and 14 knees were chronic. Fourteen(34%) meniscal tears were noted in chronic cases. In 42 soccer injuries, 20 knees were acute and 22 knees were chronic. In acute cases, 14(70%) meniscal tears were noted and in chronic cases, 14(64%) meniscal tears were noted. In 30 traffic accident injuries, 27 knees were acute and 3 knees were chronic. In acute cases, 19(70%) meniscal tears were noted and in chronic cases, 2(67%) meniscal tears were noted. There was strong trend of the increased incidence of medial involvement in the non-skiers than in the skiers, In the type of meniscal tear with acute ACL rupture, 33 of 52 meniscal were longitudinal tear, 6 were horizontal tear, 4 were radial tear(only in lateral meniscus) and 9 were complex tear. In the pattern of meniscal tear with chronic ACL rupture, 15 of 37 meniscal were longitudinal tear, 3 were horizontal tear, 1 was radial tear(only in lateral meniscus) and 18 were complex tear(medial meniscus 16, lateral meniscus 2). In the treatment of torn menisci, 29 of 52 meniscal tears were treated by conservative treatment and meniscal repair, 21 meniscal tears were treated by partial menisectomy and 2 meniscal tears were treated by subtotal menisectomy in acute injuries. In chronic injury, 10 of 37 meniscal tears were treated by conservative treatment and meniscal repair, 18 meniscal tears were treated by partial menisectomy and 9 meniscal tears were treated by subtotal menisectomy. There was no total menisectomy. As the time from injury increased, the medial meniscus tears were severe and were more likely to require menisectomy.

니트섬유강화 복합재료의 기계적 성질에 관한 연구

한길영,이동기,최병기,오환교,신용욱,전수영 조선대학교 에너지.자원신기술연구소 1999 에너지·자원신기술연구소 논문지 Vol.21 No.2

Using conventional textile techniques such as weaving, braiding, knitting and stitching it is possible to produce a wide range two and three dimensional fiber preforms. However, so far only a limited attention has been given to knitted fabrics in composite industry. This is mainly due to the opinion that knitted fabric reinforced composites posses low mechanical properties owing to their looped fiber architecture. But it is possible to obtain desired mechanical properties by selecting proper knitted fabric structure. In this paper, tensile failure load and displacement of one yarn, four yarns and knitted fabrics of ten yarns of kevlar fiber were determined experimentally in the unidirection. Mechanical properties of plain weft knitted fabrics reinforced composite intrusion beam for car side door application were investigated experimentally, which compared with desire value of American Fedral Motor vehicles Safety Standard (FMVSS) and presented the results.

둔상성 비장 손상의 선택적 치료

이봉석,박동일,안우섭,서정욱,오민구,배성한,정병욱 대한외상학회 1994 大韓外傷學會誌 Vol.7 No.1

Until recently, total splenectomy has been considered as a safe operation for splenic injuries under the misconception that the spleen could not heal spontaneously and the spleen was not necessary for the maintenance of life. Concurrent with the knowledge for immunologic function of spleen, a renewed int,erest has been evolved in the technique of splenic salvage, including splenorrhaphy, partial splenectomy, nonoperative management, and autotransplantation of splenic fragments. Authors have reviewed 47 patients with splenic injury admitted to the Department of Surgery, Dong-Guk University Hospital during the period from June, 1987 to December, 1993. The patients were classified in accordance with Cogbill s splenic organ injury scale which defines five categories for the splenic injury. Among them 30 patients were treated by splenectomy, 2 patients by partial splenctomy, 11 patients by splenorrhaphy, and 4 patients by nonoperative management. In conclusion, nonoperative management is a safe treatment option if the following criteria are satisfied: 1) absolute hemodynamic stability or rapid hemodynamic stabilization after fluid resuscitation : 2) lack of other serious intraabdominal injuries: 3) Class I or ll splenic injury by Cogbill s method.