Copper billet열간압출의 정상상태 유한요소해석에 관한 연구

이춘만,전병우 國立 昌原大學校 産業技術硏究所 1999 産技硏論文集 Vol.13 No.-

This study is concerned with a study on steady-state finite element analysis of hot extrusion for copper billet. The design of extrusion dies is still an art rather than science. Die design for a new extrusion is developed from through in-plant trials. In the present paper, axisymmetric steady-state finite element simulation program is developed. Steady-state assumption is used for both the analyses of deformation and temperature. The developed program is effectively used to simulate two cases of extrusion processes. Distributions of temperature, effective strain rate, mean strain rate and mean stress are studied for an effective design of an extrusion die.

보리 춘파재배 적응성 품종의 특성 및 선발

이춘우,구본철,백성범,손영구,김홍식 한국국제농업개발학회 2002 韓國國際農業開發學會誌 Vol.14 No.1

보리 품종 중 춘파에 적응하는 품종을 선발하기 위하여 올보리 등 16품종을 시험한 결과를 요약하면 다음과 같다. 가. 천립중과 설립량과는 상관관계가 있어 천립중이 무거울수록 10a당 설립이 적고 수량은 많아지는 경향이었다. 춘파 재배는 생육기간이 짧고 고온하에 등숙이 이루어지므로 천립중이 가벼워지는데 대립종이 소립중에 비하여 설립이 적었다. 나. 수량은 맥종간에는 쌀보리가 겉보리나 맥주보리에 비하여 적었고, 또한 년차나 품종간 변이도 컸다. 다. 쌀보리 품종들은 겉보리에 비하여 간장이 짧고, 설립이 많아 수량이 적었다. 라. 춘파재배용으로는 천립중, 설립량, 간장, 성숙기, 수량 등을 고려할 때 올보리와 사천6호가 가장 안정성이 있는 품종으로 판단되었다. This study was conducted to select varieties for spring sowing in barley. The accumulated and the average temperatures affected the 1,000-grain weight and unmatured grain yield. There was a negative correlation between 1,000-grain weight and the yield of unmatured grain. The 1,000-grain weight became lighter because of short growth period and maturing in high temperature under spring sowing condition. Compare with the covered and two-row barley, the grain was lower than naked barley. Among 16 barley varieties. "Olbori", "Sacheon6" were well adapted to spring sowing condition.

中學生의 科學과 科學敎育에 대한 認識調査

李春雨,朴敬哲 공주대학교 사범대학 과학교육연구소 1990 과학교육연구 Vol.22 No.1

The purpose of this paper is to collect the basic data to develop the middle school students understanding about science and science education. The data for this study are based on a written questionaire. After dividing the collected questionaire by school year and sex distinction, frequency and percentage was investigated. And also, χ relation(likeness) test was used in this study to tell the difference of understanding according to school year and sex destinction. The findings of this surdy are as follows: 1. Most students think that 1) science is a study which researches the world of materials theoretically. 2) science is developed by consistent research and observation. 3) science knowledge is must be proved by an experiment and that there are many ways in explaining the natural phenomena 4) science and scientists not only influence the development of human culture, but also contribute to it. 2. Most student think they have to learn science because it must be developed in order to develop techniques. 3. The students think highly of science and scientists` contribution to the development of human civilization. 4. The students not only think that science is most important, but also are interested in making an experiment and research work. But in reality the students negatively about having a job related to science of being a scientist in the future. The reason for such response is basically caused by the teachers` teaching methods which are focused on teaching the scientific knowledge in science lesson, and by teachers` carelessness dealing with scientific problems. 5. Based on the findings and analyses of the study, the following things can be concluded. (1) The students think that the aims of science is to think scientifically and to improve the ability to solve the problems creatively. (2) The students think that science education is very important. But they show little interest in studying science and find it too difficult. (3) The reasons of studying science turns our as follows: Firstly, to improve the spirit of inquiry and the ability of solving problems. Secondly, because society ban be developed only when science is developed beforehand. Thirdly, to get some more science knowledge. Fourthly, to enter an high school. (4) Most students want laboratory-centered science lesson.

ATM 망에서 Best Effort와 Guaranteed 버스트 서비스 클래스에 대한 폭주제어 방식

이우승,문규춘,박광채 조선대학교 에너지.자원신기술연구소 2000 에너지·자원신기술연구소 논문지 Vol.22 No.1

In ATM networks, we must distribute the bandwidth to use efficiently the channel and to satisfy the communication QoS(Qua1ity of Service) of traffics. However, since the required communication QoS is different according to traffics, it is expected that the congestion control scheme is improved by assigning priorities in each traffic and by controlling the priority. In this paper, congestion control schemes using the adaptive rate control for ATM LANs are presented. It is preferable for hosts in LANs to be able to send bursts at the same speed as the interface link speed in a lightly loaded condition, and as the network load increases, to reduce their traffic rate adaptively in order to avoid network congestion. We propose to apply such a rate control concept for two different traffic classed in the ATM LANs. For the first traffic class requiring no bandwidth reservation, i.e, a best effort service class, a combination of the end-to-end adaptive peak rate control with the link-by-link backpressure control is proposed. For the second traffic class, requiring the bandwidth reservation for the burst transmission, i.e. a guaranteed burst service class, a combination of the adaptive peak rate control with the fast bandwidth reservation is proposed.

티탄소 스트롬튬 상유전성 박막의 전기전도도 특성에 관한 연구

이우선,손경춘,김남오 조선대학교 에너지.자원신기술연구소 1999 에너지·자원신기술연구소 논문지 Vol.21 No.2

Temperature and frequency dispersion of dielectric permittivity was investigated on thin films of SrTiO_(3) deposited by on RF magnetron reactive sputtering. The thin films deposited on Ag/Si substrates. The SrTiO_(3) films was confirmed by XRD and it is exhibited by SEM that a uniform and fine grain structure. The electrical conduction of the films properties were dependent on temperature or frequency. Resistivity decrease with temperature and electric fild. Dielectric constant of the films properties were the highest value(ε_(r) = 300) and dependent on frequency.

트레이 자동 투입기 설계 및 개발에 관한 연구

이춘만,신성우 국립7개대학공동논문집간행위원회 2005 공업기술연구 Vol.5 No.-

A tray inserting machine is developed for automation of inserting plastic mold tray into a cardboard box. Plastic mold tray is used for protecting breakage of glass bottles. In this paper, two types of processes to divide the plastic mold tray are proposed. As a result, adhesion method by vacuum pad is accepted. And, static and modal analysis for the machine are also carried out to check the machine design using the commercial software, CATIA V5.

골수이식 후 골밀도 및 골대사의 변화 : 2년 추적관찰 2-Year Prospective Study

이원영,강무일,오은숙,오기원,한제호,손현식,윤건호,차봉연,이광우,손호영,강성구,신완식,민우성,김춘추 대한내분비학회 2000 Endocrinology and metabolism Vol.15 No.4·5

비정질 Fe_(90-x)Ni_(x)Zr_(10)(x=5, 10) 금속의 구조분석

李凞福,宋寅命,柳志旭,李春雨 公州大學校 基礎科學硏究所 1993 自然科學硏究 Vol.2 No.-

X-선 회절상을 분석하여 비정질 fe90-x NixZr10 (x=5,10) 금속의 구조를 구하였다. X-선 회절상은 2θ가 20˚ 근방과 35˚ 근방에서 전형적인 비정질 금속의 halo상을 나타냈으며, 구조인자와 원자분포함수의 각 peak는 비대칭성을 나타내어 액체금속과는 다른 구조를 보였다. 계산된 동경분포함수(RDF)의 각 peak들은 인접원자들의 분포를 나타내는 것으로서 Gaussian 함수형태를 나타내었으며, 이들을 Gaussian 함수로 각각 fitting하여 구조에 관한 변수들을 구하였다. Fe80 Ni10 Zr10의 구조분석 결과 최인접 원자배위수는 13.2이 었고, 최인접 원자간 평균거리 r0는 2.60Å, 인접원자들의 분포폭을 나타내는 Gaussian 함수의 변수 δr은 0.35Å이었다. 또한 Fe85 Ni5 Zr10의 최인접 원자배위수는 13.8이 었으며, r0는 2.62Å, δr은 0.35Å, 이었다. 본 시료의 δr은 일반적인 비정질 금속들의 값보다 훨씬 크게 나타났다. X-ray diffraction patterns of amorphous fe90-x NixZr10 (x=5,10) alloys were analyzed to obtain the structural information. The X-ray diffraction pattern of the amorphous alloys consists of typical halo-patterns at diffraction angles near 2θ = 20˚ and 35˚. And the structure factor and the atomic distribution function have unsymmetrical peaks differed from those of liquid metals. The structural parameters representing the atomic distributions of near-neighbors were obtained by Gaussian fittings to the peaks of the radial distribution function (RDF). From these parameters the estimated coordination numbers were 13.2 and 13.8, the mean distances between nearest neighbor atoms r0 were 2.60Å and 2.62Å, and the Gaussian parameters δr indicating the range of nearest atomic distribution were broth 0.35 Å for amorphous Fe80 Ni10 Zr10 and Fe85 Ni5 Zr10 alloys, respectively. The parameters δr of the amorphous allays turn out to be much larger than those of typical amorphous alloys.

師範大學 敎育課程 模型의 開發에 關한 硏究(Ⅰ) : 物理 및 地球科學 敎育課程을 中心으로 With Reference th Physics and Earth Science

李春雨,禹榮均,李華永 공주대학교 사범대학 과학교육연구소 1983 과학교육연구 Vol.15 No.1

One of the major objectives of this study is to arrange the curricula of the rhysics and the earth science course in the teachers college for improving the academic preparation of secondary school science teachers. To accomplish the objectives, the writers have preferentially analyzed the new science curriculum of the middle school and that of the physics and the earth science of the high school, and also the curricula of the physics and the earth science of the teachers college which will be applied in the pilot curriculum of the teachers college. The new science education may be characterized (1) operationally by an anal-ysis of the practician's activities, (2) intellectually by its constructs, (3) method-ologically by the mode of inquiry and procedures for problem solving. Science is the process which makes knowledge and is the interconnected se-ries of concepts and conceptual schemes that have developed as a result of experi-mentation and observations. and are fruitful of further experimentation and obser-vations. The problems set up in the analysis, in detail, are educational objectives, the contents of subject matter, the method of instruction, management of curriculum. The new and tentative curricula of the physics and the earth science in the teachers college is rearranged on the basis of both theoretical foundation and re-sults analyzed. And the new curricula of the physics and the earth science is organized on the basis of 150 credits, and also intensively, systematically, and logically. And the teaching contents of the physics and the earth science education is desirable to consist of higher level and new topics centering around the contents of secondary school science curriculum. And additionally, some of the followings concerned with the implementation of the curricular construction are suggested as the betterment. (1) Now, on-going 140 credits completion essential for the degree of B. A. for the students enrolled at the national teacher's colleges across the nation, should be strongly trengthened up to 150 credits with a view to covering the present bleak in educational achievement for producing more competent secondary school teachers, which can be said fittable for the imminent, prime objective of our teacher's colleges. (2) This study suggests the model of more reasonable curricular construction, and its actual way of implementation, which is based on the supposed 150 cred-its-completion system, which will be a help to the colleges of 140 credits-basis in curricular activities, by adding or rearranging the necessary number of courses for graduation. (3) The system, which the credits for the minor majors can be taken during the period of school vacation in addition to the regular 150 credits is safely said more desirable. Meanwhile, in the actual conducting of the above like-wise curricular activi-ties, it is supposed to be more desirable that both the choice of concerned depart-ments of the physics and the earth science and those regulations of the col-legesconcerned and ministry of education are expected to be justified in accord-ance with each other for more educational fruit-bearing, so, the more active, and long-range study and suggestions for the betterment should be activated hereafter, with no stop, for the development of our scientific education and building up our national strength itself.

동종골수이식 후 혈당 및 혈중 지질농도의 변화양상 및 관련인자

이원영,강무일,오은숙,오기원,손현식,윤건호,차봉연,이광우,손호영,강성구,신완식,민우성,김춘주 대한당뇨병학회 2002 Diabetes and Metabolism Journal Vol.24 No.6

연구배경:골수이식은 비교적 젊은 연령의 환자들을 대상으로 하며 면역억제제의 사용기간이 비교적 짧으므로, 주로 고령의 만성 질환 환자에서 시행되는 고형장기이식에서와는 달리 당대사 및 지단백 대사에 있어서 많은 차이점이 있을 것으로 추측된다. 저자들은 전향적 연구를 통하여 골수이식 후 시기별로 혈당 및 혈중지단백 변화 양상을 알아보고 이와 관련된 임상인자들을 규명하고자 하였다. 방법:1998년 10월부터 1999년 8월까지 가톨릭대학교 성모병원에서 동종골수이식을 시행한 환자들 중 43명을 대상으로 이식 전 및 이식 후 1, 2, 3, 4주와 3개월, 6개월에 공복 혈당, 혈중 총 콜레스테롤, 중성지방, 고밀도지단백을 측정하여 골수이식 후 시기별 변화를 관찰하고 여러 임상인자들에 따른 차이를 알아보았다. 결과:1. 공복혈당은 골수이식 수 첫4주 동안 상승하였고 이후 감소하였으나 이식 6개월 시점의 평균 공복혈당은 이식 전보다 유의하게 높게 관찰되었다. 혈중 총 콜레스테롤은 이식 후 1주에 최고치를 형성하였고 이후 기저수준으로 회복되었다가 이식 수 3,6개월에 다시 증가하여 기저치에 비해 유의하게 높았다. 혈중 중성지방은 이식 후 1개월까지 유의하게 증가하였고 이후 감소하여, 3,6개월에는 기저치와 유의한 차이가 관찰되지 않았다. 혈중 고밀도지단백은 이식 후 2,3주에 이식 전보다 유의하게 감소하였고 이후 이식 전 수준으로 회복되었다. 혈중 저밀도지단백은 총 콜레스테롤의 변화와 매우 유사하였다. 2. 골수이식 후 6개월 시점에서 공복 혈당이 126㎎/dL이상인 환자는 7명(16%)이었다. 이들 환자들과 공복혈당 126㎎/dL 미만의 환자 36명을 비교한 결과, 공복혈당이 126㎎/dL 이상인 환자군에서 스테로이드 평균 투여량이 많았고 고밀도지단백이 유의하게 낮았다. 3. 이식편대숙주질환이 발생한 환자는 그렇지 않은 환자보다 이식 후 1, 2, 3주 및 6개월의 총 콜레스테롤이 더 낮았고, 3개월의 공복혈당이 더 높았다. 혈연골수이식 환자군은 비혈연골수이식 환자에 비해 투여된 스테로이드 용량이 더 적음에도 불구하고 이식 후 1, 2, 3주 및 6개월의 총 콜레스테롤 수치가 더 높았다. 스테로이드 고용량 투여군(하루 평균 7.5㎎기준)은 저용량군보다 이식 후 3개월 시점의 공복혈당이 더 높았으나 나머지 시점의 혈당, 혈중 지질농도에 있어서는 유의한 차이가 관찰되지 않았다. 결론:골수이식 후 초기시기에 주로 당 대사 및 지질대사이상이 관찰되며 이는 면역억제제 투여와 관련이 있음을 알 수 있었다. 면역억제제가 고용량 투여되는 합병증 발생 시 이들 대사이상에 관심을 기울여 대처해야 할 것이다. Background: In bone marrow transplantation(BMT), recipients are usually younger and immunosuppressants are open used in shorter period than in solid organ transplantation. Therefore, there might be a difference in glucose and lipid metabolism between BMT and solid organ transplantation. However, the serial changes of metabolic parameters following BMT have not been studied. Therefore, the aim of this study is to investigate the serial changes of blood glucose, lipids and the putative factors that are related with these changes after BMT. Methods: We have prospectively investigated 43 patients who underwent allogeneic BMT. Fasting plasma glucose(FPG), total cholesterol, triglyceride and high-density lipoprotein(HDL) were measured before BMT, and at 1, 2, 3, 4, 12 weeks and 6 months after BMT. The serial changes of these metabolic parameters according to clinical factors including type of BMT, mean daily steroid dosage, and occurrence of graft versus host disease (GVHD) were examined. Results: 1. Mean FPG level increased during 4 weeks after BMT and remained above basal value at post-transplant 6 months. Total Cholesterol level was increased during initial 4 weeks after BMT and was above basal value at post-BMT of 3 and 6 months. Triglyceride level was progressively increased during initial 4 weeks after BMT, but returned to basal value there after. HDL-cholesterol level was significantly decreased during initial 4 weeks after BMT, but returned to basal value there after. 2. Patients with FPG above 126 mg/dL and the other patients, the former received larger amounts of daily steroid and had lower HDL-cholesterol level. 3. The changes of metabolic parameters were different according to type of BMT, steroid dose, and occurrence of GVHD. Conclusion: Although there was increase of FPG, TC, TG and decrease of HDL-C during initial 4 weeks after BMT, these metabolic changes recovered slowly thereafter. Immunosuppressants are thought to be associated with these changes. Further observation will be needed for the long-term effect of BMT on metabolic changes(J Kor Diabetes Asso 24:689~698, 2000).