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최병희,이종범,정장만,장경천,최병기 朝鮮大學校 機械技術硏究所 2007 機械技術硏究 Vol.10 No.2
In this study is about the fatigue characteristics which appears in the welding residual stress field. The welding residual stress takes place mostly at the portion where SS400 materials are automatical welded. The effects of the welding residual stress in the growth and propagation of fatigue crack, so as to study the fatigue behavior in the welding residual stress field. The results, in case of the load range is constant, as the stress ratio is changing to 0.1, 0.33. 0.5 the propagation life is constant but the growth life decreases. And than, when maximum load or minimum load is constant, as the stress ratio increases the growth life and propagation life increase. The fatigue crack propagations rate da/dN appears to accelerate when the stress intensity factor range △K is less than 15MPa-m^(1/2). The growing and propagation fatigue crack in the welding residual stress field is similar to original specimen after being passed the original residual stress field.
순수 Ti 용접재의 기계적 특성 및 피로크랙 성장특성에 관한 연구
최병희,이종범,정장만,장경천,최병기 朝鮮大學校 機械技術硏究所 2007 機械技術硏究 Vol.10 No.2
In this study, fatigue fracture often occurs due to the fatigue crack in the machine and welding structure and this is the result of severe operational environment, operational condition, and design condition caused by the large scaled and light weighted machine and structure in recent days. Therefore, safety and reliability should be secured to prevent the fatigue fracture of machine and structure, and the use of titanium has been increased in the metal material for the safety and reliability. The purpose of this thesis was to investigate the welding characteristics and fatigue crack growth characteristics of titanium, commonly using power station, aircraft and ship. The experimented material was TIG welded in order to look over the characteristics according to the notch position and compare with other material. The results, at the same welding condition, 4 pass specimen which had the smallest number of welding pass had the highest tensile strength with 51kgf/㎟ and the tensile strength of 4 pass specimen was 10% higher than the one of 7 pass specimen, and its elongation reduced about 30%. The initial fatigue crack growth characteristic is slower in this order, boundary zone < welding zone < HAZ < base metal. Especially boundary zone's growth speed is slower about 30 times than base metals.
초음파 기관지 내시경으로 진단한 기관기관지 골연골형성증 1예
이천우,옥철호,정만홍,장태원,임성경,조은주,이신준,이혜원,구상건,천봉권 고신대학교 의과대학 2011 고신대학교 의과대학 학술지 Vol.26 No.2
Tracheobronchopathia osteochondroplastica (TO) is a rare benign disease of unknown etiology characterized by accumulation of calcium phosphate in the submucosa of large airways and benign proliferation of bone and cartilage resulting in nodular formation. We report a case of tracheobronchopathia osteochondroplastica diagnosed by Endobronchial ultrasonography in a 56-year-old man. Chest Computed Tomography revealed thickening of tracheal and bronchial wall, and multiple nodules through whole trachea. Endobronchial ultrasonography showed numerous submucosal nodules with hetero-echogenecity in the third and fourth layers. Histopathological examination revealed nonspecific bronchitis with squamous metaplasia and metaplastic ossification. We confirmed tracheobronchopathia osteochondroplastica. The patient's symptoms were successfully treated with antibiotics and oxygen supplyment. endobronchial ultrasonography can helpful diagnosis in tracheobronchopathia osteochondroplastica.
심장압전을 유발한 잡견에서 Pentastarch 투여 후 Dobutamine, Hydralazine, Sodium Nitroprusside 에 대한 혈역학적 반응
이정호,김진모,장영호,전재규 대한마취과학회 1998 Korean Journal of Anesthesiology Vol.35 No.5
Background : Cardiac tamponade results in a hemodynamic disorder associated with decreased cardiac output and blood pressure. To improve cardiac output in a subject with cardiac tamponade, cardiotonic drugs and vasodilators with blood volume expander can be used. The purpose of this study was to observe the hemodynamic effects of cardiotonic drugs and vasodilators following administration of plasma expander in the dogs with cardiac tamponade. Method : Three groups of dogs were studied during the induced cardiac tamponade. Following infusion of pentastarch, group I received dobutamine by dripping of 10ug/kg/min, followed by injection of 20ug/kg/min, group II received hydralazine (20 mg, 40 mg) and group III received sodium nitroprusside (5ug/kg/min, 10 g/kg/min). The heart rate, blood pressure, cardiac output and pulmonary arterial occluded pressure were measured. The atrial transmural pressure was calculated by subtracting intrapericardial pressure from mean atrial pressure. Results : Cardiac output was increased in the groups I and II, but mean arterial pressure was increased in only the group I. Atrial transmural pressure was not changed in all three groups. Conclusion : The most pronounced hemodynamic improvements during the cardiac tamponade is observed in group I with pentastarch-dobutamine combination. (Korean J Anesthesiol 1998; 35: 852∼860)
김기진,장재익,이순천 啓明大學校 生活科學硏究所 2002 科學論集 Vol.- No.-
Since most of the studies on golf have focused on the psychological social, and biomechanical aspects of golf, the relationship between body composition and fitness level of golfer and golf performance is well known. The purpose of this study was to identify the differences of body composition and physical fitness between professional and amateur golfers. To provide background knowledge about the effect in golf participation on the physical fitness level, physique, body composition, and fitness level of 10 professional and 10 amateur golfers were measured and analyzed by t-test. Results of the study were as the following. 1. BMI, RI, WHR indices determined by anthropometric measurements were not different between professional and amateur golfers. 2. The subcutaneous fat tend to be thicker in professional golfers than amateur golfers, although the difference was not statistically significant. 3. In terms of physical fitness tests, professional golfers tend to get higher scores in back strength, stork stand with eyes closed, vertical jump, sit-up, sit-and-reach, and fitness index than amateur golfers, although the difference was not statistically different. In grip strength, side step, and trunk-and-neck extension, however, professional golfers received significantly(p<0.05) higher scores than amateur golfers.
시호(柴胡)(Bupleuri Radix)추출물이 고지방식이를 급여한 흰쥐의 혈청지질 및 항산화계에 미치는 영향(影響)
이장천,이은,Lee Jang-Cheun,Lee Eun 대한한의학방제학회 2003 大韓韓醫學方劑學會誌 Vol.11 No.1
Effects of siho(Bupleuri Radix) extracts on lipid composition and antioxidant system were investigated in rat fed high fat diet. body weight gain, concentration of plasma triglyceride, total cholesterol, LDL-cholesterol showed a tendency to decrease in siho(Bupleuri Radix) extracts groups. However, the concentration of HDL-cholesterol showed no significantly different among treatments. Plasma and liver TBARS concentration showed a low values in siho(Bupleuri Radix) extracts groups. Activities of SOD, GSH-Px and CAT showed a tendency to increase in siho(Bupleuri Radix) extracts groups.
실험연구 : 실험견에서 간혈류 차단 및 재관류 시 소량의 Nitroglycerin 투여에 의한 간혈류와 실시간 국소 간관류 및 산소 이용률의 변화
전재규 ( Jae Kyu Cheun ),정정길 ( Jung Kil Chung ),배정인 ( Jung In Rae ),김진모 ( Jin Mo Kim ),김애라 ( Ae Ra Kim ),장영호 ( Young Ho Jang ),안윤정 ( Youn Jeong An ),이용철 ( Yong Cheol Lee ) 대한마취과학회 2003 Korean Journal of Anesthesiology Vol.45 No.2
GMA용접에서 유전자 알고리즘을 이용한 비드높이 예측 모델 개발에 관한 연구
손준식,김일수,장경천,이동길 한국공작기계학회 2006 한국공작기계학회 추계학술대회논문집 Vol.2006 No.-
Gas metal arc welding process has been chosen as a metal joining technique due to the wide range of usable applications, cheap consumables and easy handling. Three main indicators such as arc voltage, welding speed and welding current have a big influence in the quality welding. Since all these factors affect the quality of the welded joining parts, the effect of these parameters was investigated experimentally. In this paper, an attempt has been made to develop the predicted models (quadratic and cubic) for bead height using genetic algorithm. Performance of the developed models were proved to be compared to the regression equation.
이기용(Ki-Yong Lee),박순섭(Sun-Sub Park),장경천(Kyeung-Cheun Jang),이호재(Ho-Jea Lee) 한국기계가공학회 2006 한국기계가공학회 춘추계학술대회 논문집 Vol.2006 No.-
Recently, according as request for parts of complex shape is increased, 5-axis machining has been studied actively. A impeller is a important part that is used at turbo engines of airplane and automobile, compressors, etc and it is representative part that 5-axis machining is necessary. In this research, to product a impeller using 5-axis cutting method, 5-axis machining center was evaluated in terms of its dynamic characteristics and thus cutting conditions were optimized. Also, in 5-axis cutting, cutting force signals were measured and analyzed. Finally cutting properties were invested to find optimum tool path for 5-axis cutting of an impeller.