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.

다공질 실리콘에서 전기루미네선스의 시간 의존성

李春雨 公州大學校 基礎科學硏究所 1994 自然科學硏究 Vol.3 No.-

단결정 실리콘(p형)을 불화수소 속에서 양극 산화반응으로 다공질 실리콘을 제작하고 액체접촉에 의한 전기루미네선스 세기와 spectrum이 시간에 의존되는 특성을 조사하였다. 그 결과 EL의 세기는 전체 발광시간의 15∼20%되는 시간에 최대로 나타났으며 그 후에는 서서히 감소하였으며 제작시간에 비례하였다. 또한 발광의 지속시간은 재작시간에 비례하였으며 다공질층에 존재하는 Si-H bonds가 사라지기까지 계속되는 것으로 나타났다. EL spectrum은 발광의 시작과 끝 사이에서 장파장쪽에서 단파장쪽으로 변화하였으며, 변화의 폭은 약 90nm 정도로 나타났다. The porous silicon layers(PLS) were fabricated from p-type silicon wafers by electrochemical anodization. The time dependence of intensities and spectra of electroluminescence(EL) from PLS and electrolyte interface was investigated in Na2SO4 aqueous solution. The experimental results shows that EL intensities were peaked at 15 to 20 percents of total luminescent time and gradually diminished. The luminescent intensity and duration are proportional to length of the fabrication time. The result suggests that the luminescence lasted until Si-H bonds disappear from the porous layers. The EL spectra were shifted about 90nm to high frequency during the luminescence.

브리지만법에 의해 성장된 p-GaSe 단결정의 전자 이동도에 관한 연구

이우선,김남오,손경춘 조선대학교 에너지.자원신기술연구소 1999 에너지·자원신기술연구소 논문지 Vol.21 No.1

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.

정부관리에서 민간관리로 전환하는 일본의 신 맥류정책

이춘우,백성범 한국국제농업개발학회 2002 韓國國際農業開發學會誌 Vol.14 No.2

일본의 맥류 생산, 연구, 보급, 가공 및 유통에 대한 정책의 전개 방향을 설정한 신 맥류정책이 발표되었으며 이를 해설한 日本의 麥政策 이라는 책이 출간되었다. 이 책에는 향후 일본의 맥류 생산, 연구, 보급, 가공 및 유통에 대한 정책 설명과 정부의 대책이 해설하고 있다. 이 책이 우리나라의 맥류정책 수립에 참고자료로 활용될 수 있도록 요약하여 소개한다. 1. 생산자, 수요자 및 정부가 각자가 신 맥류정책에 부합한 생산비 절감을 위한 종합적인 노력하고, 문제점은 장기적인 시간을 가지고 해결을 모색한다. 2. 국내산 맥류는 민간유통에 맡기고, 생산자와 실수요자가 품질평가를 반영하여 직접 인수체계를 만들고 양질의 맥류생산 계획을 세운다. 3. 연구개발의 충실 및 강화로는 생산자, 실수요자의 의견을 품종개발에 반영하기 위하여 개발단계부터 생산자와 실수요자의 평가를 반영할 수 있는 새로운 체제를 설정한다. 4. 외국산 맥류는 국가무역에 의한 정부가 계획적으로 수입 및 효율적인 운영을 도모한다. 5. 사료용 맥류는 증산제도는 대체사료의 개발, 보급, 각종기업대책 등의 추진하여 2002년까지 폐지하고 특정맥류를 SBS(매매동시입찰)방식으로 단계적으로 도입한다. Japans agricultural situation is similar to Korea where many food crops are imported and the sector is heavily protected. The Ministry of Agriculture, Forestry and Fisheries in Japan announced a new policy to develop the wheat and barley sub-sectors. This policy aims to increase attention given to the cultivation, research, extension, and dissemination of technologies for these crops. The basic strategy is to transfer the management and control of wheat and barley from the government to the private sector. The production of wheat in Japan does not meet its demand because local wheat does not have good quality and price. This is one of the reasons why milling companies do not buy Japanese wheat. This study was conducted to look into this new policy and compare it with the developments in the Korean wheat and barley sub-sectors.

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.

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.

다공질규소 microcavity의 페브리-페로 필터 특성

이춘우,박대규,홍사용,김영유,전종현 公州大學校 基礎科學硏究所 1999 自然科學硏究 Vol.8 No.-

p형 단결정규소 웨이퍼를 15% HF-에탄올 용액에서 양극 산화시켜 다공질규소를 얻는 과정에서 전류밀도에 따라 굴절률이 변하는 다층의 다공질규소층(porous silicon multilayer)을 구현하였다. 그리고 다층의 다공질규소층(I), 다공질규소 발광층, 또 다른 다층의 다공질규소층(II)의 순으로 구성된 porous silicon microcavity(PSM)를 제작하고 그 물성을 조사하였다. PSM 상하에 위치한 다층의 다공질규소층의 단면을 AFM(Atomic Force Microscope)으로 조사한 결과 고굴절률과 저굴절률이 주기적으로 교차하는 층이 균일하게 형성되었으며, 중앙의 다공질규소 발광층도 균일하게 나타났다. 다층의 다공질규소층 및 다공질규소 발광층의 두께를 각각 실효파장의 1/4배 및 2배가 되도록 하였을 때 특정파장의 필터로 쓰일 수 있는 페브리-페로 간섭 필터(Fabry-Perot interference filter)의 특성이 나타났다. 또한 PSM의 발광 스펙트럼은 그 반치폭이 현저히 감소하고 발광의 세기가 크게 증가되는 경향을 보였다. 또한 발광파장을 600 nm로 조절하여 PSM을 구현하고 발광 특성을 관찰한 결과 600 nm 부근에서도 같은 현상이 일어나 발광의 최대 봉우리 파장값을 이동시킬 수 있는 필터로서의 역할이 가능함을 보였다. In the process of obtaining porous silicon by anodizing p-type doped crystalline silicon wafer in 15 % HF-ethanol solution, we obtained porous silicon multilayers which had periodically varying refractive index by the current density. We fabricated the porous silicon microcavity(PSM) which consist of porous silicon multilayers(I), active layer of porous silicon and porous silicon multilayers(II) and investigated its physical properties. The AFM(Atomic Force Microscope) measurement from the cross section of multilayers I and II) shows uniformity of high refractive index and low index layers as well as the active layer. We observed the characteristics of Fabry-Perot interference filter when the thickness of layers was 1/4 and the thickness of active layer was twice of the effective wavelength, which can be used as a filter for specific wavelength. We found the emission characteristic from the PSM, which FWHM(Full Width Half Maximum) was considerably decreased and emission intensity was increased. And as a result of fabricating PSM which consisted of 600 nm in the light emission wavelength and observing the light emission properties, We found out that there was the same phenomenon in 600 nm wavelength and PSM could act as a filter which could shift the maximum of the emitted light.

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.

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.