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수평연속주조한 과공정 Al-Si 합금 소경봉의 미세조직 및 기계적 성질
김완철,박지하,류봉선,박원욱 ( Wan Chul Kim,Ji Ha Park,Bong Sun You,Won Wook Park ) 한국주조공학회 1997 한국주조공학회지 Vol.17 No.6
N/A Hyper-eutectic Al-17.5wt%Si alloy bars of 25 ㎜ in diameter were produced by horizontal continuous casting process. Effect of both casting speed and primary Si refiner (AlCuP) on microstructure and mechanical properties of the alloy have been investigated. With increasing a weight fraction of AlCuP, the average primary Si size decreased down to 20 ㎛. On the contrary, there was no notable changes of microstructure and primary Si size according to the casting speed in the experimental range of this study, indicating that the cooling rate should be increased to optimize and refine microstructure and primary Si size. The experimental results including hardness, tensile strength and wear resistance tests of the processed alloy bars showed a good possibility to develop the high performance wear resistant Al-Si alloy. (Received October 21, 1997)
김완철 ( Wan Chul Kim ),신재욱 ( Jae Uk Shin ),진수신 ( Su Sin Jin ) 대한소화기학회 2021 대한소화기학회지 Vol.77 No.1
Hydatid cysts are caused by an infestation with larval tapeworms of the genus Echinococcus. The disease is endemic in developing countries but has rarely been reported from immigrant workers in Korea. This paper reports a case of hepatic hydatid cyst in a 27-year-old female. She was referred with abdominal pain that had persisted for the past 2 months. The patient was a foreign worker from Mongolia. The physical examination was unremarkable, and blood tests showed peripheral blood eosinophilia and elevated liver enzymes. Abdominal ultrasonography showed a well-circumscribed cystic mass with septation in the liver. A surgical resection was performed for complete removal. After uncomplicated postoperative recovery, the patient was discharged with albendazole 400 mg twice daily. The hydatid cyst is an important disease that should be considered in the differential diagnosis of cystic lesions in the liver, particularly in those who have lived in endemic areas. A correct early diagnosis based on the typical image findings is important for early treatment before the rupture of the cyst, which is associated with low morbidity and mortality. A current surgical resection combined albendazole are effective treatments for hepatic hydatid cysts, associated with low recurrence rates. (Korean J Gastroenterol 2021;77:35-38)
증례 : 순환기 ; 심부전 환자에서 발생한 반복적인 자발성 저혈당과 의식저하 1예
김계환 ( Kye Hwan Kim ),김완철 ( Wan Chul Kim ),이은주 ( Eun Ju Lee ),고진신 ( Jin Sin Koh ),박정랑 ( Jeong Rang Park ),함종렬 ( Jong Ryeal Hahm ),황진용 ( Jin Yong Hwang ) 대한내과학회 2014 대한내과학회지 Vol.87 No.2
저자들은 반복적인 저혈당에 의한 의식저하를 주소로 내원한 심부전 환자로 수술적 치료 이후 1년간 저혈당 및 심부전 악화 없이 외래 경과관찰 중인 환자 1예를 경험하였기에 문헌고찰과 함께 보고하는 바이다. Hypoglycemia in adults without diabetes can be caused by drugs, critical illness, hormone deficiency, and hyperinsulinism. Spontaneous hypoglycemia in congestive heart failure has been reported rarely in adults. We report a case of spontaneous hypoglycemia in congestive heart failure in a 73-year-old woman with mitral stenosis and atrial fibrillation who had been receiving treatment for 6 years. She had two episodes of low serum glucose with unconsciousness, but there was no evidence of diabetes. Heart failure with concomitant hepatic dysfunction was presumed to have caused the hypoglycemia. She underwent mitral valve replacement after being diagnosed with severe mitral stenosis. There was no episode of hypoglycemia during follow-up. (Korean J Med 2014;87:205-208)
부동스트레스(immobilization stress)가 심방근육세포에 미치는 영향에 관한 미세형태학적 관찰
이무삼(Moo Sam Lee),송창호(Chang Ho Song),김형태(Hyung Tae Kim),한의혁(Eui Hyeog Han),이광소(Guang Zhao Lee),김완철(Wan Chul Kim),신해영(Hae Young Shin) 대한체질인류학회 2002 해부·생물인류학 (Anat Biol Anthropol) Vol.15 No.1
간추림 부동스트레스 (Immobilization stress) 가 심방근육세포 마치는 영향을 알아보기 위하여 흰쥐를 2시간, 6시간, 12시간, 24시간 동안 움직일 수 없는 좁은 판에 넣어 부동스트레스를 준 다음 심방의 미세형태학적 변화를 관찰하여 다음과 같은 결과를 얻었다. l 부동스트레스 2시간군에서는 심방근육세포의 미세구조 변화가 별로 관찰되지 않았다. 부동스트레스 6시간부터 12시간군에서는 심방근육세포의 미세구조 중 특히 사립체, 근육원섬유, 과립의 위치 변화가 관찰되었으며 부동스트레스 및 24시간군에서는 일부 세포가 6시간군보다 성한 변화 양상을 보인 반면 대부분의 세포는 6시간군에서 보다 약한 미세구조 변화를 보였다. 부동스트레스에 의한 심방근육세포의 미세구조 변화는 사립체의 팽대, 사립제능선의 파괴, 부분적인 세포질의 과립화, 말이집구조를 갖고 있는 소포, 심방근육세포의 세포자멸사, 사이원반 사이의 넓어짐, 근육원섬유의 용해, 큰 뭇소포체의 형성 등이었다. 2 부동스트레스 24시간군에서는 크기가 매우 작은 사립체들과 크기가 다양한 분비과립이 핵의 한 극 부위의 세포질 속에서 다수 관찰되었다. 3 부동스트레스 후 분비과립은 구심적으로 세포의 가운데로 몰려는 경향이었으며 이때 크기가 큰 파립의 전자밀도는 강했고 크기가 작은 과립의 전자 밀도는 약했다. 이상의 경과는 심방의 기능을 좀 더 잘 이해할 수 있게 해주며 또한 앞으로 심방의 분비과립 동태를 연구하기 위한 모델로 이용될 수 있으리라 생각된다.
급성 관상 동맥 증후군으로 오인된 식도 벽내 혈종 1예
유대곤 ( Dae Gon Ryu ),최철웅 ( Cheol Woong Choi ),강대환 ( Dae Hwan Kang ),김형욱 ( Hyung Wook Kim ),정동일 ( Dong Il Jeong ),김완철 ( Wan Chul Kim ),신재규 ( Jae Gyu Shin ),임태원 ( Tae Won Lim ) 대한소화기학회 2017 대한소화기학회지 Vol.69 No.4
Intramural hematoma of the esophagus is a rare condition that can be spontaneous or secondary to trauma, toxic ingestion, or intervention. If it is the spontaneous type, it usually presents initially with epigastric pain, hematemesis or dysphagia. We present a case of intramural hematoma of the esophagus mimicking acute coronary syndrome. A 63-year-old man presented with severe acute chest pain. He has four coronary stents that were inserted five years ago, from a different hospital, and is on dual antiplatelet agents. Coronary angiography was performed immediately under the suspicion of acute coronary syndrome, and we found that there was no obvious clogging of the coronary arteries. Next, chest computed tomography was performed due to suspected aortic dissection, and the result was also negative. Four days later, endoscopy was performed and intramural hematoma covered with large ulcers was diagnosed. (Korean J Gastroenterol 2017;69:239-242)
金完哲 弘益大學校 産業技術硏究所 2004 産業技術 Vol.14 No.-
The effects of homogenization on hot rolling properties of gravity cast AZ31-xCa (x=0~2.0wt.%) alloys were evaluated by examination of surface and microstructures of sheets. The side cracking during hot rolling was decreased by homogenization by the elimination of local inhomogeneity and dissolution of brittle precipitate into matrix. The coarse grains in raw materials were changed to fine grains with the average particle size of 5~10μm by the dynamic recrystallization during repeated hot rolling . A deformation twinning was more favorably formed in the hot-rolled sheets after homogenization. It is considered that the grains grow and the precipitates are solved into the matrix during homogenization heat treatment, which results in increasing the possibility of formation of deformation twinning during hot rolling.
g-2Ca-0.3X계 합금의 첨가원소에 따른 용탕산화 거동
金完哲,김문회 홍익대학교 산업기술연구소 2001 産業技術 Vol.11 No.-
This study has examined the ignition characteristics and oxidation resistant of the non-combustible Mg- 2Ca-0.3 weight % X(Al, La, Nd, Y) alloys in an attempt to develop new alloy systems that can subject to melting in the atmosphere and also prevent natural ignition of chips produced in mechanical working. Both the ignition property and oxidation resistant were found to improve significantly in any case where one of the third elements was added to the binary MG-2Ca alloy. The new alloy systems also improved the solidification characteristics, and their ingots were found to be relatively free from impurities and thermal crack whose presence is hard to avoid in the production of pure Mg ingots. The oxidation experiments with molten metals at 700℃ and 750℃ for 1 and 5 hours showed that the addition of Al or Y causes fine and dense oxide layers to develop. The oxide layers appear to suppress the grower of MgO products and thereby enhance the resistance of the alloys to ignition and burning. In alloys with the Y addition, the thickness of oxide layers did not show any significant change with the increase in temperature and time, indicating that the Y is relatively stable compared with that of Mg-2Ca. The ignition temperature of Mg-2Ca alloys, which is 100℃ higher than of pure Mg, increased by 100℃ with the addition of 0.3 weight % Al. There was a substantial increase in the ignition temperature as much as 800℃ in Mg-2Ca alloys containing both Al and Y by 0.3 weight %.
기계적 합금화에 의한 급속냉각된 Al 분말의 조직과 기계적성질의 개선
金完哲 홍익대학교 산업기술연구소 1996 産業技術 Vol.6 No.-
Severe working of splats produced a very fine grain size and substructural strengthening. The dispersed particles were spherical and much finer then those obtained by conventional SAP. MA-AI splats extruded bars had the recrystallized grains when isothermally aged for 100 hours at 450℃. At higher temperature, hower, only the Al_2O_3 patricles pinned the grain boundaries. Accordingly grain size become smaller and grain boundary sliding was retarded, providing a superior high temperature hardness as the amount of Al_2O_3 increased.