ECAP 강가공에 의한 5083 Al 합금의 초소성 변형

이정국,서창우,김병철,신동혁 漢陽大學校 工學技術硏究所 2000 工學技術論文集 Vol.9 No.1

초기 결정립 크기가 200 μm인 상업용 5083 Al 합금에서 equal channel anglar pressing(ECAP) 강가공에 의하여 결정립을 초미세화 시킬 수 있었다. ECAP는 200℃에서 수행되었고, 반복 passes시 180˚ 회전을 주면서 같은 시편에 8 passes까지 강가공을 가하였다. 미세조직 특징은 1 pass후 평균 0.2 μm의 폭과 0.8 μm의 길이를 갖는 연신된 평행한 bands가 균일하게 형성 되었고, 4 passes후 결정립 크기가 약 0.3 μm인 등축의 초미세 결정립이 얻어졌다. 이러한 초미세 결정립을 갖는 5083 Al 합금에서 저온 초소성 성질이 얻어졌는데, 약 0.5 μm의 결정립 크기를 갖을 때 250℃이하의 온도에서 연신율이 200 %이상인 초소성 거동을 나타내었다. An ultrafine grained structure was introduced into a commercial 5083 Al alloy with the initial grain size of ∼200 μm using the equal channel angular pressing technique. Equal channel angular pressing was successfully conducted at 200℃ and the results showed that the microstructure was reasonably homogeneous after single passage and consisted of parallel bands of elongated substructure having the average width of 0.2 μm and the average length of 0.8 μm. Repetitive passes were conducted on the same sample up to total 8 passes through the die so that the sample was rotated 180˚ around its longitudanal axis between passes. An equiaxed ultrafine grained structure of ∼0.3 μm was obtained in the present alloy after 8 passes. It was found that a 5083 Al alloy with the grain size of ∼ 0.3 μm exhibited a superplastic-like behavior with elongation to failure in excess of 200% below.

自動倉庫와 保管品의 最適配置에 관한 硏究

李相玩,申大赫,兪炳哲 동아대학교 공과대학 부설 한국자원개발연구소 1990 硏究報告 Vol.14 No.1

This paper deal with the concept of AS/RS and the closest available location is AS/RS. Travel-time model and minimum cost model have developed for automated storage/retrieval machine. In this article, it is shown that arrival loads follow Poisson process and duration times are independent of each other and have i. i. d. distribution. The objective of this study is mainly compare with existing research and propose new approach method to optimal location. We give approximate method for the K closest location.

월경주기 증상의 요인 분석

이수일,유태혁,강종선,안석철,이병욱,김헌,석재호 大韓神經精神醫學會 1986 신경정신의학 Vol.25 No.1

404 nurses and nurse-aids rated their experiences of 45 symptoms(Moos' Menstrual Distress Questionnaire) of the menstrual, premenstrual and intermenstrual phase on a 4 point scale separately. The 45 symptoms were inter-related and factor analyzed separately for each phase. six common clusters of symptoms emerged from 3 phases, which were labeled concentration, motor tension, pain, pleasurable affect, autonomic reactions and water retention. Four clusters of symptoms emerged from premenstrual phase. These clusters were labeled instabillity, withdrwal reactions, depression and headache. The factor named unpleasurable affect emerged from intermenstrual and menstrual phase. Above findings were differed from the results of Moos' study in which eight basically replicated clusters of symptoms emerged from three phases. Through discussion of validity of this scale, and differences between results of Moos' and this study, we came to the conclusion that sampling of subjects, prospective longitudinal symptoms reporting, amount of variance in a symptom over the course of menstrual cycle and proper choice of factor analysis method would be salient variables to construct valid scale for measuring menstrual cycle symptoms.

韓國科文硏究 : 詩ㆍ賦를 中心으로

李炳赫 부산대학교 사범대학 1986 교사교육연구 Vol.13 No.-

The Korean Classic Literature is closely related to the sentences of Korean Civil Service Examination at the days of the Korea and Lee Dynasty. because the men of letter of those days were selected into the proper authorities only through the Examination. Because of this reason, those sentences have been treated as an invaluable one in the literature world up to now. But no one can deny that those sentences have been criticized to the high level in the point of its technique. In considering those conditions, the writer described the kinds, the forms, the tendency of test, and the literary meaning in this paper.

多目的 意思決定問題의 對話型 技法에 관한 硏究

李相道,兪炳哲,申大赫 동아대학교 공과대학 부설 한국자원개발연구소 1989 硏究報告 Vol.13 No.2

Decision making problem is the process of selecting a possible course of action from all the available alternatives. Recently, the above problem has been considerable interest in the treatment of multiple objective in the decision making process. This paper deals with an interactive method for solving the multiple objective mathematical programming. The interactive multiple objective decision making depend on the progressive definition of the decision maker's preferences among with the exploration of the criterion space. An interactive algorithm which is efficient and useful to assist a decision maker in finding his most preferred efficient solution to the multiple objective mathematical programming is presented. To compare several technique with regard to criteria and an illustration of numerical example is included.

소아 만성 부비동염에서 단순촬영상과 OMU CT상의 비교

이병돈,박상호,김장묵,이승균,장혁순,강주원,김장욱 순천향의학연구소 1998 Journal of Soonchunhyang Medical Science Vol.4 No.1

Most commonly and widely used diagnostic tool for chronic paranasal sinusitis in children is plain X-ray check not only because of small radiation dose and easy performance, but because of low cost. However ostiomeatal unit computed tomography(OMU CT) was known to be more accurate and recommended recently by many physicians. The author have studied for both OMU CT and plain X-ray of paranasal sinuses and compaird their findings in 90 chidren(180 sides of sinus) aged from 4 to 14 years who suspected having sinusitis. OMU CT was taken after plain X-ray examination (Caldwell's view, water's view, lateral view), and the time interval betweeen these two examination was O to 14 days (average 4.7 days). The following results were obtained. Considering that OMU CT was accurate, the rate of correspondence in diagnosis of sinus pathology between plain X-ray and OMU CT was 48.3% in the ethmoid sinus, 51.1% in the maxillary sinus, 41.9% in the sphenoid sinus, 43.4% in the frontal sinus. If all OMU CT findings had been accurate, the incidence of false positives according to plain X-ray was 25.5% in the ethmoid sinus, 28.3% in the maxillary sinus, 70.8% in the spenoid sinus and 77.8% in the frontal sinus. While, the incidence of false negatives according to plain X-ray was 85.9% in the ethmoid sinus, 70.5% in the maxillary sinus, 50.0% in sphenoid sinus and 37.5% in the frontal sinus. A routine preoperative OMU CT is recommended, which allows a detailed evaluation of pathologic changes and anatomical relations of the paranasal sinuses before surgical interventiaon for the paranasal sinuses. Considering the above facts, diagnosis of pediatric sinusitis only by plain X-ray was inadequate and OMU CT was necessary.

퍼지 환경하에서 유연생산시스템 일정계획의 Pairwise 해법에 관한 연구

이상완,신대혁,윤연근,박병주 동아대학교 공과대학부설 생산기술연구소 1996 生産技術硏究所硏究論文集 Vol.1 No.2

FMS(Flexible Manufacturing System) scheduling problem is a complex system and a NP-hard problem. Thus it is natural to look for heuristic method. Here, we consider the multi-part production scheduling problem in a FMS scheduring of altemative routings. The problem in more complex if the processing time is imprecision. It requires suitable method to deal with imprecision. Fuzzy set theory can be useful in modeling and solving scheduling problems with uncertain processing times. Lee-Ki fuzzy number comparison method will be used to compare processing times that evaluated under fuzziness. This study propose heuristic algorithm solving FMS scheduling problem under fuzzy environment. In this algorithm, the pairwise comparision method is used to find proper alternative routing. On the basis of the proposed method, and example in presented.

p-n 접합을 이용한 ISFET의 전기적 절연

이강열,강명성,김창수,서화일,권대혁,손병기 경북대학교 센서기술연구소 1992 센서技術學術大會論文集 Vol.3 No.1

결합조직형성 모종 1예

이병진,노진혁,조옥자,박시룡 대한피부과학회 2003 大韓皮膚科學會誌 Vol.41 No.1

Desmoplastic trichilemmoma is a rare variant of trichilemmoma characterized by typical features of trichilemmoma with abundant desmoplastic stroma. We report herein a 54-year-old man presented with 2-year history of a solitary bean sized verrucous nodule on the occipital scalp. Histologically, the tumor showed a well-defined lobular growth extending from the epidermis into the dermis with abundant central desmoplastic stroma. Epithelial lobules at the margins of the neoplasm showed the typical features of trichilemmoma composed of glycogen-rich clear cells and peripheral palisading columnar cells. In contrast, at the center the cells assume a more random pattern of cords and strands traversed by the hyaline stroma, mimicking invasive carcinoma. It was diagnosed desmoplastic trichilemmoma by the distinctive histologic appearance and totally excised. (Korean J Dermatol 2003;41(1) : 120∼122)

Ta₂O_(5) 게이트 pH-ISFET의 제조 및 그 동작특성

권대혁,김명규,이광만,손병기 경북대학교 센서기술연구소 1991 센서技術學術大會論文集 Vol.2 No.1

To improve sensing characteristics of the pH-ISFET using LPCVD-grown Si_(3)N_(4), Ta_(2)O_(5) thin film depositied by RF reactive sputtering was used for hydrogen ion sensing gate and investigated sensing characteristics at various annealing temperatures. The XRD pattern showed that the crystal structure of the Ta20s thin film was amorphous when the annealing temperature was less than 500℃, δ-Ta_(2)O_(5) poly-crystal at MC Ta_(2)O_(5) gate pH-ISFET annealed at 400℃, O_(2) ambient for 1hour, the AES and RBS spectrum showed good stoichiometry (O/Ta=2.5). And its sensing characteristics showed good linearity and high sensitivity(57~59MV/pH) in the wide pH range(pH 2~12), and excellent long-term stability (0.03~0.05 pH/day). It can be concluded from these results that the sensing characteristics of Ta_(2)O_(5) gate pH-ISFET is more excellent than Si_(3)N_(4) gate pH-ISFET.