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전기화학적 분석을 통해 산출된 코팅 결함율이 트라이볼로지적 특성에 미치는 영향 평가
김우중(Woo-Jung Kim),안승호(Seung-Ho Ahn),김호건(Ho-Gun Kim),김정구(Jung-Gu Kim),조정우(Chung-Woo Cho),이영제(Young-Ze Lee) 한국트라이볼로지학회 2004 한국윤활학회지(윤활학회지) Vol.20 No.6
Many of the current development in surface modification engineering are focused on multilayered coatings, which have the potential to improve the tribological properties. Four different multilayered coatings were deposited on AISI D2 steel in this study. The prepared samples are designed as WC-Ti_(0.6)Al_(0.4)N, WCTi_(0.53)Al_(0.47)N, WC-Ti_(0.5)Al_(0.5)N and WC-Ti_(0.43)Al_(0.57)N. The multilayered coatings were investigated with respect to coating surface and cross-sectional morphology, roughness, adhesion, hardness, porosity and tribological behaviors. Especially, wear tests of four multilayered coatings were performed by using a ball-on-disc configuration with a linear sliding speed of 0.017 m/sec and a normal load of 5.38 N load. The tests were carried out at room temperature in air by employing AISI 52100 steel ball (H_R = 66) having a diameter of 10 ㎜. The surface morphology, and topography of the wear scars of samples and balls have been determined by using scanning electron spectroscopy (SEM). Also, wear mechanism was determined by using SEM coupled with energy-dispersive spectroscopy (EDS). Results have showed an improved wear resistance of the WC- Ti_(1-x)AlxN coatings with increasing of Al (aluminum) concentration.
전기화학적 분석을 통해 산출된 코팅 결함율이 트라이볼로지적 특성에 미치는 영향 평가
김우중(Woo-Jung Kim),안승호(Seung-Ho Ahn),김호건(Ho-Gun Kim),김정구(Jung-Gu Kim),조정우(Chung-Woo Cho),이영제(Young-Ze Lee) 한국트라이볼로지학회 2004 한국트라이볼로지학회 학술대회 Vol.38 No.-
Recently, many of the current development in surface modification engineering are focused on multilayered coatings. Multilayered coatings have the potential to improve the tribological properties. Four different multilayered coatings were deposited on AISI D2 steel. The prepared samples are designed as WC-Ti0.6Al0.4N, WC-Ti0.6Al0.4N, WC-Ti0.53Al0.47N and WC-Ti0.43Al0.57N. The multilayered coatings were investigated with respect to coating surface and cross-sectional morphology, roughness, adhesion, hardness, porosity and tribological behavior. Especially, wear tests of four multilayered coatings were performed by using a ball-on-disc configuration with a linear sliding speed of 0.017 m/sec, 5.38 N load. The tests were carried out at room temperature in air by employing AISI 52100 steel ball (HR = 66) having a diameter of 10 ㎜. The surface morphology, and topography of the wear scars of samples and balls have been determined by using scanning electron spectroscopy (SEM). Also, wear mechanism was determined by using SEM coupled with EDS. Results have showed an improved wear resistance of the WC-Ti1-xAlxN coatings with increasing of Al concentration.
김우중(Woo-Jung Kim),김재훈(Jae-Hoon Kim),장중철(Jung-Cheol Jang),김범수(Beom-Soo Kim),유근봉(Keun-Bong Yoo) 대한기계학회 2011 대한기계학회 춘추학술대회 Vol.2011 No.10
The Heat Recovery Steam Generator(HRSG) is device that uses exhaust gas of gas turbine to increase thermal efficiency. In order to requirements global needs saving energy, reducing emission of CO2, reducing cost, many power plant appled HRSG. Generally, High Cr steels are used in steam side tube because of its high temperature strength and oxidation resistance. This paper addresses creep-rupture test of 9Cr-1Mo steel at isothermal temperature with change thermal and stress condition. the results of date are plotting to Larson-Miller parameter. Through hardness test of specimens, fluctuation of hardness values are determined to interrelation between hardness and life. Finally, The test specimen of creep rupture is observed by Transmission Electron Microscope(TEM) to analyze higt temperature material behavior of Cr steels
소아 만성 염증성 탈수초성 다발성 신경병증의 치료 및 효과
김우중(Woo Joong Kim),최선아(Sun Ah Choi),김수연(Soo Yeon Kim),김헌민(Hun min Kim),임병찬(Byung Chan Lim),황희(Hee Hwang),최지은(Ji eun Choi),김기중(Ki Joong Kim),채종희(Jong Hee Chae) 대한소아신경학회 2016 대한소아신경학회지 Vol.24 No.4
목적: 본 연구는 소아 만성 염증성 탈수초성 다발성 신경병증 환자의 임상 양상을 분석하고 그에 따른 다양한 치료 방법과 예후에 대한 연구를 함이 목적이였다. 방법: 2004년부터 2014년 까지 서울대학교 어린이병원 뇌신경센터를 방문하였던 환자 중 EFNS/PNS 진단 기준에 의거하여 소아 만성염증성 탈수초성 다발성 신경병증으로 진단된 10명의 환자를 대상으로 후향적 의무기록 분석을 시행 하였다. 환자들은 일차 약제로 면역글로불린, 정맥용 스테로이드 또는 혈장교환술을 사용하였다. 일차 약제에 반응 하지 않을 경우 면역억제제를 추가하였다. 결과: 10명(남아 4명, 여아 6명)의 소아 만성 염증성 탈수초성 다발성 신경병증 환자들의 평균 진단 나이는 8세였고, 평균 추적관찰기간은 46.2개월이었다. 본 연구에서 소아 만성 염증성 탈수초성 다발성 신경병증 환자들은 8명(80%)에서 아급성 경과를 보였고, 6명(60%)에서 다상성 경과를 보였다. 4명의 단상성 경과를 보이는 환자들은 면역 글로불린(양호 반응 0%, 부분 반응 75%)에 비해 혈장교환술(양호반응 50%, 부분반응 50%)을 시행하였을 때 양호한 치료 결과를 보였다. 또한 진행성 경과에서 스테로이드는 효과가 없었다. 반면에 6명의 다상성 경과를 보이는 환자들은 면역 글로불린(양호 반응 50%, 부분반응 50%)과 혈장교환술(양호반응 40%, 부분 반응 60%)에서 유사한 치료 반응을 보였다. 5명의 다상성 환자들은 일차 치료에서 불응기 경과를 보였고, 그 중 4명의 환자들은 사이클로스포린 투약 후 양호 반응을 나타냈다. 8명의 환자들은 6개월 동안 재발을 보이지 않아 장기적인 치료 경과는 양호하였다. 결론: 진행하는 단상성 소아 만성 염증성 탈수초성 다발성 신경병증에는 조기 혈장교환술이 효과적이며 불응기 다상성 소아 만성 염증성 탈수초성 다발성 신경병증에는 사이클로스포린이 효과적이었다. Purpose: To investigate the clinical features of childhood chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) as well as the treatment responses and outcomes. Methods: We retrospectively analyzed clinical features and treatment outcomes of 10 cases of childhood CIDP followed up for more than a year. Intravenous immunoglobulin (IVIG), IV steroid and plasmapheresis was considered as the first line therapy and used according to patient’s response. Immunosuppresant agent was added when patients did not respond to the first line therapy. Results: 10 CIDP cases (4 male and 6 female) were enrolled, and the median age of onset was 8 years (range 3-15 years). The mean duration of follow up was 46.2 months (range 12-82 months). Our patients manifested more frequently with subacute onset (n=8, 80%) and polyphasic course (n=6, 60%). All ten patients had lower extremity weakness at presentation (100%), six patients complained of upper extremity weakness (60%), and three patients reported sensory changes (30%). In the monophasic course (n=4), plasmapheresis showed a better treatment response (good 50%, partial 50%) compared to IVIG (good 0%, partial 75%) and steroids (good 0%, partial 0%), especially in progressive phases. In the polyphasic course (n=6), IVIG (good 50%, partial 50%) and plasmapheresis (good 40%, partial 60%) showed similar treatment responses. Five patients were refractory to first line treatment and received immunosuppressants; four patients received cyclosporine and achieved successful disease control without significant side effects. The overall long-term outcomes were favorable, with eight patients (80%) showing minimal symptoms and no relapse within 6 months. Conclusion: Our results suggest that early administration of plasmapheresis in progressive monophasic course and cyclosporine in refractory polyphasic course may be effective in childhood CIDP.
김우중(Woo Joong Kim),이명석(Myung Seok Lee),이준상(Jun Sang Lee),김지현(Ji Hyun Kim),양형원(Hyung Won Yang),김경환(Gyoung Hwan Kim),김경희(Gyoung Hee Kim) 대한소화기학회 1997 대한소화기학회지 Vol.30 No.5
Acquired tracheoesophageal fistula through esophageal diverticulum is infrequent, and they are caused by carcinoma, trauma, infection, and traction. The most common clinical findings are cough associated with eating, production of sputum mixed with food, and weight loss with profound weakness. In the vast majority of patients, diagnosis was made using esophagography, fiberoptic esophagoscopy and bronchoscopy. We reported a case of non-malignant tracheoesophageal fistula through esophageal diverticulum combined with aspiration pneumonia found in a 34 year old woman who complained of chronic coughing, fever, and frequent episodes of paroxysmal coughing. Patients symptom and condition improved after surgical repair including fistulectomy with esophageal repair, and segmental lobectorny. (Korean J Gastroenterol 1997; 30:677-683)