Er^3+ 단결정의 광학적 Energy Gap의 온도의존성 : Er^3+ Single Crystals CdGaInS_4 및 CdGaInS_4

최성휴,방태환 조선대학교 기초과학연구소 2000 自然科學硏究 Vol.23 No.1

CdGaInS_4 and CdGaInS_4:Er^3+ single crystals crystallized in the rhombohedral (hexagonal) structure, with lattice constants a=3.913A˚, c=37.245A˚for CdGaInS_4, and a=3.899A˚, c=36.970A˚for CdGaInS_4:Er^3+. The optical absorption measured near the fundamental band edge showed that the optical energy band structure of these compounds had a direct and indirect band gap, the direct and indirect energy gaps are found to be 2.771 and 2.503 eV for CdGaInS_4, and 2.665 and 2.479eV for CdGaInS_4:Ef^3+ at 10 K. The temperature dependence of the optical energy gap was well represented by the Varshni equation. In CdGaInS_4, the values of α, βof the direct and the indirect energy gap were found to be 7.57x10^-4eV/K, 6.53x10-4eV/K and 240K, 197K, and the values of αand βof the direct and the indirect energy gap in the CdGaInS_4:Er^3+ were given by 8.28x10^-4eV/K, 2.08x10^-4eV/K and 425K, 283K, respectively.

재구성 가능형 공작기계의 주축 시스템 설계

장성현,정용민,황현영,최영휴,박종권 한국공작기계학회 2008 한국공작기계학회 춘계학술대회논문집 Vol.2008 No.-

During a decade, there are many researches on microfactory which is the miniature, flexible, and efficient manufacturing system for the micro/meso scale machining device. Moreover many micro machine tool has developed in Japan, U.S., Europe, and Korea. Already we developed a 3-axis micro milling machine with 300×200×320 ㎣ machine size for microfactory. In this study, we introduce the design of a high speed spindle system with air bearings for our micro milling machine. Desired operation speed range of the spindle system is 100,000 ~ 150,000 rpm. In. design step, we have consideration for minimum critical speed, compliance, and weight construction of the spindle system. The shaft length, the shaft outer diameter, bearing positions and bearing stiffness were set as the design values. After the final design of spindle model, we carried out dynamic analysis a spindle system for a micro milling machine by using ADROS, which is our own developed S/W for dynamic design analysis of rotor systems. As the result, we designed a spindle system having the critical speed above the operating speed.

모 제약회사 근로자들의 직업성 천식 유병률과 약제 분말 노출수준

오성수,최용휴,김은아,이영목,장재길,유장진,박승현,김태균,정수영,김규상,강성규 大韓産業醫學會 2006 대한직업환경의학회지 Vol.18 No.2

목적: 제약회사에서 직업상 천식의 유병 규모를 파악하고 작업공정에 대한 작업환경 측정을 통해 제약회사의 약제 분말에 대한 노출수준을 평가하고자 하였다. 방법: 제약회사에서 약제 분말에 노출되는 근로자를 대상으로 천식을 선별하기 위하여 설문조사 및 진찰, 혈액검사, 폐기능 검사 그리고 피부단자시험을 실시하였고, 각 부서별 공정에 따라서 총분진과 항생제 또는 효소제 분말에 대한 작업환경 측정을 실시하였다. 직업상 천식이 의심되는 근로자에 대하여 기관지과민성에 대한 검사(메타콜린을 이용한 비특이 기관지유발시험)와 약제 분말 기관지유발시험을 실시하여 확진하였다. 결과: 설문조사 및 진찰에서 작업 관련 천식 증상이 있는 근로자는 11명(34.4%)이었고, 약제 분말을 이용한 피부단자시험에서 1+ 이상 반응을 보인 근로자 10명(31.2%)이었다. 비특이 기관지유발시험 결과 8명(25.0%)이 양성(PC20 ≤16 mg/ml)이었다. 약제 분말 기관지유발시험을 통해 직업상 천식으로 확진된 근로자는 5명(15.6%)이었다. 작업환경 측정에서 원료를 충진하거나 투입하는 작업 그리고 정립작업에서 약제 분말에 대한 노출이 많았다. 결론: 제약회사에서 직업상 천식은 주로 제조공정 중 약제 분말에 노출된 근로자에서 발생하여, 증상 및 직업성 천식의 유병률이 높았다. 따라서 원료를 충진 또는 투입하는 작업과 정립작업 등 제조과적에서 약제 분말 노출을 줄이기 위한 세심한 주의가 필요하여, 약제 분말을 취급하는 근로자에 대해서는 천식 증상 조사뿐 아니라 정기적으로 피부단자시험, 비특이 기관지유발시험 등을 실시하여야 할 것이다. Objectives: After the investigation of one worker with occupational asthma, we surveyed the preva- lence of occupational asthma and the exposure level of pharmaceutical dust of 32 workers in a pharmaceutical company. Methods: Thirty-two of the 90 employees participated in the survey which consisted of questionnaire, blood sampling, spirometry and skin prick tests with 8 common allergens as well as 9 antibiotics and 2 enzymes. Various indices of the working environment were also measured. Subjects who had a symptom suggestive of work-related asthma or positive skin prick test were further investigated by PC20 methacholine. Nine subjects who had a PC20 result of 16 mg/ml or less (n=7) or had work-related symptoms and positive skin prick test (n=2) were referred to undergo a specific bronchial provocation test to phar- maceutical dust in an academic allergic disease center. Results: Eleven of 32 workers (34.4%) had a work-related symptom suggestive of occupational asthma. Ten (31.2%) showed positive skin prick test. 8 (25.0%) had a PC20 result of 16 mg/ml or less (indicative of significant bronchial hyperresponsiveness), and 5 (15.6%) had a positive result on the specific bronchial provocation test. Exposure levels of stuffing, input of raw materials and screening process were relatively high. Conclusions: This survey showed that pharmaceutical workers have an increased risk of occupational asthma. Although pharmaceutical factories maintain a relatively good working environment, careful control of respiratory tract exposures, especially during stuffing, input or raw materials and screening process, is important to prevent occupational asthma. Pharmaceutical workers need to undergo regular skin prick and methacholine bronchial provocation tests, as well as asthmatic symptom survey, to ensure the early detection and prevention of occupational asthma.

Undoped 및 Er-doped ZnGaInS_4 단결정의 성장과 광학적 Energy Gap

최성휴,방태환 조선대학교 기초과학연구소 2000 自然科學硏究 Vol.23 No.1

ZnGaInS_4 and ZnGaInS_4:Er^3+ single crystals crystallized in the rhombohedral (hexagonal) structure, with lattice constants a=3.831A˚, c=46.107A˚for ZnGaInS_4, and a=3.862A˚, c=46.283A˚for ZnGaInS_4:Er^3+. The optical absorption measured near the fundamental band edge showed that the optical energy band structure of these compounds had a direct and indirect band gap, the direct and indirect energy gaps are found to be 3.165 and 3.001 eV for ZnGaInS_4, and 2.956 and 2.752eV for ZnGaInS_4:Ef^3+ at 10 K, respectively. The temperature dependence of the optical energy gap was well represented by the Varshni equation. The values of α, βof the direct and the indirect energy gap were found to be 9.56x10^-4eV/K, 11.6x10-4eV/K and 353K, 455K for the ZnGaInS_4, and the values of α, βof the direct and the indirect energy gap in the ZnGaInS_4:Er^3+ were given by 9.71x10^-4eV/K, 4.93x10^-4eV/K and 266K, 299K.

Undoped 및 Co-doped ZnIn₂S₄단결정의 광학적 Energy Gap의 온도의존성

최성휴,강대진,방태환 조선대학교 기초과학연구소 2001 自然科學硏究 Vol.24 No.-

ZnIn₂S₄ and ZnIn2S4 : Co^(2+) single crystals crystallized in the rhombohedral(hexagonal) space group C^(5)_(3v)(R3m). with lattice constants a =3.852 Å, c=37.215Å for ZnIn₂S₄ and a=3.823 Å and c=36.975 Å for ZnIn2S4 : Co^(2+). The direct and indirect energy gaps are found to be 2.771 and 2.672 eV for ZnIn₂S₄ and 2.301 and 2.156eV for ZnIn2S4 : Co^(2+) at 300K. The temperature dependence of the optical energy gap was well represented by the Varshni equation. the values of α and β of the direct and the indirect energy gap were found to be 4.504×10^(4)eV/K, 2.407×10^(-4) eV/K and 35K, 14K for the ZnIn₂S₄, and the values of α, β of the direct and the indirect energy gap in the ZnIn₂S₄ : Co^(2+) were given by 3.262×10^(4) eV/K, 4.121×10^(-4)eV/K and 23K, 31K.

볼나사로 이송되는 공작기계 이송계의 진동해석

차상민,배희은,최진호,최영휴 국립7개대학공동논문집간행위원회 2003 공업기술연구 Vol.3 No.-

During high-speed running of machine tools, serious vibrations often may occur in their feed-drive system. In this paper, a 4-D.O.F. planar motion model is proposed in order to analyze a ball screw feed-drive system. The equations of motion are derived for the proposed model and natural frequencies of the system are calculated. Also its transient response due to driving motor speed control input are calculated. The theoretical analysis results showed good agreement with experimental ones measured from a laboratory feed-drive test system. Consequently we concluded that the proposed 4-D.O.F model can be well applicable to the vibration analysis and dynamic design of machine tool feed-drive system.

평면 2자유도 모델을 이용한 리니어 모터로 구동되는 다축 마이크로 밀링머신 크로스헤드의 진동해석

장성현,황현영,정용민,최영휴,홍정표 한국공작기계학회 2008 한국공작기계학회 추계학술대회논문집 Vol.2008 No.-

In this paper, a simple 2-D.O.F. planar motion model is proposed in order to analyze the snake motion of a cross head assembly of a Multi-axis micro milling machine (M4) for BT-factory, that is travelling on linear guide. In the proposed mathematical model, the friction between head and guide ways is neglected, and also the support structures including the linear guides of M4 are assumed to be rigid. The equations of motion of the proposed model are derived and successfully solved to determine vibration responses of a cross head assembly due to some applied traction forces.

데스크탑 밀링머신의 고속 스핀들 설계 해석

장성현,황현영,정우영,홍정표,최영휴 한국공작기계학회 2009 한국공작기계학회 춘계학술대회논문집 Vol.2009 No.-

During a decade, there are many researches on microfactory which is the miniature, flexible, and efficient manufacturing system for the micro/meso scale machining device. Moreover many micro machine tool has developed in Japan, U.S., Europe, and Korea. Already we are developing a desktop milling machine with 380×450×450 ㎣ machine size for microfactory or BT (Bio technology) factory. In this study, we carried out the design analysis of a high speed spindle system for our desktop milling machine by using ADROS, which is our own developed S/W for dynamic design analysis of rotor systems. As the result, we obtained some analyzed dynamic characteristics of a spindle system, such as natural frequency, whirl frequency, critical speed, and harmonic response.

우리나라 綿織物의 史的 考察

임성휴,신인수 圓光大學校大學院 1996 論文集 Vol.17 No.-

This thesis studied among India, the cradle of cotton fabric culture, its outskirts eastern Asia, China, Korea and Japan, mutual relations of cotton fabric cultural formation and the development process of cotton fabric production. The cotton fabric culture originated from India about 2500 B.C. and spread to Asia including Korea, Europe and throughtout the world. It also had developed and settled according to the trait of those regions. It was in 1362, the twelfth1 year of King Kongmin, at the end of Koryo dynasty that Mun Ic-Jeom brought into cotton seeds from the Won Country (one of Chinese dynasties) however in the three-kingdom age as people traded with those of Min (민)(Bok Gun Sung, 福建省) and Kwang(廣)(Kwang Dong Sung, 廣東省) provinces of China, they was able to product 'Baik chup po(白疊布·白첩布, a kind of textile)' with brought-in cotton from China by using their skill of fine cotton-spinning. Baik chup po was sent to China as a tribute in three-kingdom rige and Koryo dynasty on the other side Baikjae dynasty sent 'Baik Myun(白綿, a kind of cotton fabric)' to Japan and affected the Japan cotton fabric culture. In Chosun age cotton fabrics became universal and ranked as main cloth, but they were collected severely as taxes and there were a variety of prohibitive measures of clothes according to their social positions. The cotton fabric industry didn't come to develop qualitively and stayed at a domestic hand-operating industry until the late of Chosun dynasty. For those reasons in the enlightened age, it declined Chosun textile manufacturing company in 1917 due to excellent (superior) imported cotton fabrics but as Kyungsung textile manufacturing company in 1919 were established, gradural cotton-production industrialization started. After that our country's cotton industry developed consecutively and in the 1960's it made a great contribution to the development of nation economy. In the 1990's as the stage of automatization on the one hand they try to promote productivity and the other hand, according to developed countries' diversification and differentiation trends they make effors to develop the advanced new material.

이산화된 탐색공간에서 다구찌 방법을 이용한 구조 최적설계에 관한 연구

장성현,정우영,정용민,권봉철,최영휴 한국공작기계학회 2008 한국공작기계학회 추계학술대회논문집 Vol.2008 No.-

Nowadays, there are several design problem having discrete variables in the industrial fields. The researchers are using the optimization method, such as genetic algorithm (GA), simulated annealing (SA), design of experiment (DOE) and taguchi method (TM), to solve it's design problem. Moreover, people want to decrease the computational cost and time. Therefore, in this paper, we proposed the iterative optimization algorithm which repetitively searched a local region to find best solution in discrete searching space using TM. The optimal solution in each local region is obtained by S/N ratio for the evaluation function that consists of the objective function and penalty function. Also, we have applied our algorithm to 3-bar, 10-bar, and 25-bar truss optimization problem.