SiCw / Al 복합재료의 열처리에 따른 계면현상에 관한 연구

李義吉 大田工業大學 1992 한밭대학교 논문집 Vol.9 No.2

In the present study, the effects of Al/sic interface reaction and the formation of Al_4C_3 compounds on the mechanical properties of the Al/siC composites prepared by squeeze casting were investigated. After squeeze casting, the size of dendrites in Al without whiskers were larger than those with whiskers. The hardness of composite materials(about 72 Hv) was found to be approximating 40% higher than that of matrix metal(29Hv), which gradually increases with heat treatment time showing maximum hardness at 12hr. The observation of increasing number of compounds in 12hrs heat treatment suggests that these compounds are responsible for the increase of hardness. E.P.M.A. analysis suggested that the formation of Al_4C_3 compounds near Al/SiC interface occurs through diffusion of Si in SiC into Al matrix. By X-ray diffraction studies, those compounds was identified to be Al_4C_3. The tensile strengh of composite materials was gradually decresed by heat treatment, which was in contrast to the behavior of hardness. With increasing heat tretment time, the fracture mode of composite materials was changed from large dimples and pull-out form of fiber to the fracture and rupture form of fiber.

피아노후레임 제조기술에 관한 연구

이의길,최양진,조덕호 한밭대학교 산업과학기술연구소 1994 논문집 Vol.2 No.-

Effects of chemical composition, inoculation, shape of graphite and matrix structure upon the mechanical properties and damping capacity of cast iron were investigated. Tensile strength and Rockwell hardness of cast iron were increased by inoculation. The depth of chill and distortion for the manufactures were improved by shape of graphite and matrix structure. The damping capacity was attributable to the characteristic property of graphite.

CoMFA 법을 이용한 3-아릴이소퀴놀린 화합물들의 SK-OV-3 암세포에 대한 가상의 약물 작용 수용체 해석

김의기,민선영,정병호,천승훈,최보길,조원제 전남대학교 약품개발연구소 2002 약품개발연구지 Vol.11 No.-

We have performed a 3D-QSAR/ CoMFA analysis of the cytotoxiv activities of thirty-five 3-arylisoquinoline derivative against SK-OV-3 tumor cell line. The results suggested that the electrostatic, steric and hydrophobic factors of 3-arylisoquinoline were strongly correlated with the antitumor activity. Considerable predictive ability (cross-validated r2 as high as 0.841) was obtained through CoMFA.

公共土地開發事業 地方化問題와 代案에 관한 小考

조길환,황의진,김영곤 여수대학교 1998 論文集 Vol.13 No.2

Since 1980 the Korea Land Development Coporation has played a major role in land development by means of a Public Initiated Land Development Scheme. This strategy has attempted to correct the market failure of the generation of large sum of windfall profits. In accordance with reimplementation of the local autonomous ruling system since 1991, the demend for local government initiated land development have increased rapidly as local governments attempt to math the influence of national local development policy. In this regards, it is very useful for urban planners to analyze the merits and dismerits of the local government initiated land development schemes in view of national agency's development. This paper recommends several mitigation measures to improve the settlement of the local government initiated land development scheme.

19C 영국 청소년 문학 속에 나타난 남성다운 인간상의 스포츠

하남길,정의진 한국체육사학회 2003 체육사학회지 Vol.11 No.-

In the process of modernization, a great deal of British and American sports culture was diffused into out own educational system as well as our livelihood. However we lacked research in the areas such as the origin and background to the development of British sports culture. In a general point of view British Sports culture was a creation of several factors such as British politics, society, geography, religion and nationality. However in an ideological sense, the single most influential factor in the development of British sports culture was Muscular Christianity and at the nucleus of Muscular Christianity was the concept of manliness. Therefore this article was written with two main objectives. Firstly, 19th century juvenile literature and its ideals of masculinity were examined in order to reveal the figure of a manly juvenile. Secondly, this article examines the rearing of masculine juveniles and its correlation with the development of sports. In novels by Thomas Hughes such as BOP(The Boys Own Paper) the character of a masculine gentleman illustrated was similar to that of a Middle Age Knight with outstanding prowess in sports. This was the appearance of a typical gentleman of the late 19th century and among the characteristics demanded of them were; bravery, honesty, honour, patriotism, loyalty between friends, exceptional ability in masculine sports, empathy for the weak, an unyielding stance against the strong, manners and a worthy attitude of the defeated. That is to say, a courageous and loyal knight of the old. In order to create a template of a manly gentleman in upper class education, training of youths in organisations such as the Boyscout in addition to sports and outdoor activities were considered vital. These physical training bore the intent of prolonging the tradition of sturdy manliness. In addition, an ethical temperament was also emphasised. However, further emphasised than this ethical quality in juvenile literature of this age was to incite in youths the idol of a man; aggressive and harsh, brave, relentless and one that does not step back in the face of battle. To encourage these male temperaments, sports was considered important and as a result sports developed earlier in Great Britain than in other nations.

입자 분산된 2024 Al기 복합재료의 열처리 거동에 관한 연구

李義吉 한밭대학교 산업과학기술연구소 1993 논문집 Vol.1 No.-

2024 Al composites were manufactured using SiC and Al_2I_3 reinforcements for the changes of volume percentage(5v/o, 10v/o and 20v/o). For the homogeneous distribution of powder particles for the volume percentage, jar mill was using for 20hrs and composite samples were obtained under the conditions of 490℃ 30MPA at hot press for 1hrs. After hest treatments for heating conditions, homogeneous, solid solution and aging seperately, physical and mechanical properties of composites were observed by SEM, optical microscope, XRD and micro hardness. In conditions, SiC reinforcement composites were observer better properties then Al reinforcement, and case of SiC, the hardness after aging treatments were 5.5-26.5% higher than the composites after manufactured.

강산 및 강알칼리 음독에서 냉각 용액을 사용한 희석 요법과 중화 요법의 가능성

이중의,송형곤,김동훈,권운용,곽영호,서길준,윤여규 대한응급의학회 2001 대한응급의학회지 Vol.12 No.3

Background: There is no effective treatment modality for caustic agent ingestion. Dilution and neutralization are prohibited because of the risk of secondary thermal injury. This experiment is designed to evaluate the amount of dilution and neutralization heat and to gauge the applicability of dilution and neutralization therapy using cold solutions to suppress the peak temperature. Methods: This is an in-vitro chemical experiment. HCl, CH3COOH, NaOH, and NH4OH are selected as representatives of strong and weak acids and strong and weak alkali, respectively. 20℃, 11.6M, 5.8M, and 2.9M solutions of each acid and alkali are made and mixed using a magnetic stirrer at a room air temperature of 28℃. The peak temperature, the duration above 40℃, and the heat amount are measured or calculated. Results: When a 11.6M HCl or NaOH solution is diluted with same amount of water, 32 or 18cal. per mL of HCl or NaOH is produced, respectively. HCl produces a significant peak temperature, but NaOH does not. The lower the concentration, the lower the amount of heat production. 11.6M CH3COOH and NH4OH solutions don't produce dilution heat.11.6M and 5.8M solutions of all acids and alkali produce destructive neutralization heat. However, 2.9M solutions produce neutralization heat which might be controllable. When a 11.6M HCl or NaOH solution is neutralized with a -10℃ 2.9 M NaOH or HCl solution, respectively, the peak temperature produced is below 40℃ and seems to add little thermal damage to viable tissue. Conclusion: Dilution and neutralization with a cold solution in cases of strong acid or alkali ingestion is a promising method to avoid thermal injury.

119구급대를 통한 서울지역 외상환자 진료체계에 대한 통계분석

서길준,이승한,조익준,권운용,송형곤,이중의,윤여규 대한응급의학회 2001 대한응급의학회지 Vol.12 No.2

Backgroud: Despite continous efforts to improve the prehospital trauma care system in Korea, the preventable death rate has been reported to be high. The purpose of this study was to evaluate the prehospital trauma care system in Seoul by analyzing 119 rescue databases. Methods: The 119 rescue data bases of 22,275 trauma patients, who were transported to the secondary and tertiary hospital in Seoul by Seoul 119 rescue services from January 1, 2000 to December 31, 2000, were analyzed. Results: The response time(mean 3.7 min.) showed no time, weekly, and regional variations. However, the transport time from field to hospital showed was high in the morning rush hour(7:00 to 10:00 am), and was gradually decreased and the lowest between 10:00 pm and 7:00 am. There was also a regional variation in the transport time, which was short in the central area and long in the peripheral area of Seoul. Prehospital cares were given to the 10,999 trauma patients(49.4%). Of the 464 unresponsive patients(2%), only 236 patients were identified in transported hospitals. The outcomes of these unresponsive patients were DOA(54%), survival(19%), death in ER(14%), transfer to other hospitals(8%), and death after admission(5%) in order. Conclusion: We suggest that this study may be helpful to the establishment and improvement of the prehospital trauma care system as well as the determination of the adequate numbers and locations of trauma center in Seoul.

패혈증 백서 모델에서 비타민-C의 효과

이중의,신상도,표창해,서길준,정성은,윤여규 대한응급의학회 1999 대한응급의학회지 Vol.10 No.4

Background : Multi-organ failure from sepsis is very lethal disease entity, which is suspected to be caused by activated inflammatory cells. Inflammatory cells activated by endotoxins generate oxidants and cytokines such as TNF-α and IL-6, which in turn stimulate macrophages and neutrophils. Augmented inflammation makes an organ-injury deteriorate into an organ-failure, which may progress to multi-organ failure. This study is designed to evaluate the therapeutic effects of vitamin-C, a scavenger of oxidants, in sepsis. Methods : Male Sprague-Dawley rats were divided into 3 groups : a control group, a group injected intrapetoneally with LPS(lipopolysaccharide), and a group injected intraperitoneally with LPS and vitamin-C. Each eight rats were sacrified 24 hours and 48 hours after injection, and samples of the blood, the liver and the lung were obtained. Biochemical assays of TNF-α level in the blood and malondialdehyde(MDA)level, catalase activity and nitric oxide synthase(NOS)activity in the liver and the lung tissues were performed. Results : Serum TNF-α level, tissue lipid peroxidation and tissue i-NOS activity were dramatically increased, and tissue catalase activity was exhausted rapidly in sepsis. High dose vitamin-C administration decreased serum TNF-α level, tissue lipid peroxidation and tissue i-NOS induction, and protected against catalase exhaustion. Conclusion : high dose vitamin-C therapy was proved to have definite antioxidant effect in septic condition.

입자 분산된 2024 Al기 복합재료의 기계적 성질에 관한 연구

李義吉 大田産業大學校 1993 한밭대학교 논문집 Vol.10 No.2

This study was performed in order to find mechanical properties variation according to heat treatment of Al composites strengthened by means of dispersing SiC, Al2O3 particulate and the extrusion temperature during extrusion. The composites were fabricated by vacuum-hot pressing for 1hr with each, pressure of 30MPa at 490℃ according to volume fraction variation(5v/o, 10v/o and 20v/o) of SiC, Al_2O_3 and then this composites were homogenized-aged, followed by microhardness test, tensile test and the observation of fracture plane, and was measured with microhardness tester after anealing for 90 minutes at intervals of 50℃ from 300℃ to 450℃. For microhardness test, hardness values increased with aging treatments, compared with homogenization treatments. This study concluded these increases of hardness valus are due to formation of precipitate phase (Θ'). Also, at tensile test, the relatively low values of tensile strength, elongation indicated that strength drops occure because of interface formation between matrix and strengthened material due to uniform mixture. The fracture type presented ductile fracture type as volume fraction of strengthened material decreases and presented brittle fracture type as the volume fraction increase. This study found that the optimum of extrusion temperature is 400-450℃.