• Proceedings of the Korean Society of Precision Engineering Conference
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• 1996.04a
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• pp.813-818
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• 1996

This paper presents a method for tolerance design using the Taguchi Method(TM) and general purpose mechanism analysis program. Also the tolerance design method is with respect to performance improvement of a mechanism. To use the orthogonal array, mathematical model of a mechanism is established and experiments are carried out by the general purpose mechanism analysis program. The contact model is used to consider a clearance effect. This method is applied to the tolerance design of the VTR Deck mechanism. This method can be used in tolerance design of general mechanisms.

• Journal of the Korean Society for Precision Engineering
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• v.13 no.6
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• pp.66-77
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• 1996

This paper presents a method for tolerance design using the Taguchi Method(TM) and general purpose mechanism analysis program. Also the method is tolerance design with repect to performance improvement of a mechamism. To use the orthogonal array, mathematical model of a mechanism is established and experiments are carried out by the general purpose mechanism analysis program. The contact model is used to consider a clearance effect. This method is applied to the VTR Deck mechanism. This method can be used in tolerance design of general mechanisms.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.39 no.11
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• pp.1153-1162
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• 1990

The torque ripple reduction method is studied to improve the speed fluctuation of permanent magnet flat type brushless DC motors. To reduce the torque ripple, this study developed the compensation method of the 5'th harmonics component of air gap flux waveform which pass through the driving coils. 1/2 inch VTR was considered. As the result of this study, we can reduce the torque ripple and the speed fluctuation of the capstan motor about 20% then before and we can obtain not only better characteristics of wow/flutter but more useful capstan motors which can be applied in the multi-function VTRs.

• Journal of the Korean Magnetics Society
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• v.7 no.4
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• pp.217-224
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• 1997

컴퓨터를 포함하는 정보통신기기를 비롯하여 TV, VTR, 세탁기 등의 가전기기, 자동차와 항공기 등의 수송기기, 생물 환경 계측기기, 안전 보안기기 등 이루 헤아릴 수 없는 각종 전자, 기ㅖ장비에 광 적외선 센서, 자계 자속 센서, 위치 변위 센서, 역학량 센서, 오도 센서, 응력 센서 등 다양한 센서가 사용되어 기기의 정밀성, 자동화, 신뢰성 및 안정성 등을 획기적으로 향상시키고 있으며, 그 외에 공장생산 현장의 능률 제고와 정밀도의 향상, 안전 쾌적성의 확보, 정보교환 및 전달의 고도화, 일상생활의 고도 시스템화, 사회복지의 구현 등에도 큰 기여를 하고 있다. 그런데 이러한 흐름은 앞으로도 계속되어 전자공학을 필두로 하여, 전력공학, 메카트로닉스 분야와 의공학, 공업계측공학등의 발전을 기초로 하여 산업 및 사회시설의 자동화, 무인화 및 정보화가 빠르게 진전됨에 따라 다양한 센서에 대한 수요가 크게 늘 것으로 예측되고 있다.

• Journal of Industrial Technology
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• v.14
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• pp.119-125
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• 1994

Ultra-precision machine tool equipped with the diamond bite tip is used to machine optical products, drums of VTR or computer hard disk. It needs nano technology in the surface roughness of workpiece. To perform the nano scale machining, ultra-precision machine tool must be designed and manufactured in consideration of the vibration characteristics. In this paper, using the finite element analysis, we investigate the modal parameters of the ultra-precision machine tool structures, which use cast iron, granite and alumina ceramic for the bed materials. To verify the numerical results, we manufacture a model of ultra-precision machine tool using granite bed and perform impulse test. Through the theoretical and experimental analyses, we could compare and estimate the vibration characteristics of the three models for the ultra-precision machine tools.

• IE interfaces
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• v.12 no.2
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• pp.174-179
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• 1999

This paper describes the development of low cost, miniaturized multi-function image splitter for an unmanned guard system. The essential equipments of an image splitter system consist of a video system which displays in one screen images inputted by several cameras, a frame switcher which records each image sequentially in VTR, and TBC(Time Base Control) system which prevents image flickering during image switching. Currently, the price of similar system on the market is high, system management and repair are difficult, and bulky space is required. Futhermore, since currently available frame switcher can record only 30frame/sec, if eight cameras are installed, each camera image is recorded at the low speed of 3.75frame/sec, and consequently skip some images which may be vital for legal evidence. In this research, we have solved the problem of low speed recording by recording the video screen of splitted images at 30frame/sec and zooming each image when play back.

• Proceedings of the KIEE Conference
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• 1999.07g
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• pp.3212-3214
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• 1999

RS(Reed-Solomon)부호는 오류 정정을 위한 채널 코딩기법중의 하나로 특히 연집 오류에 대해 강한 특성을 갖고 있으며, CD-P(Compact Disc Player), DAT(Digital Audio Tape). VTR, DVD(Digital Video Disc), 디지탈 TV 디코더등에서 사용되고 있다. 본 논문은 Galois Field, GF[$2^8$]상에서 (204. 188. 8)의 규격을 갖는 디지탈 TV용 RS 복호기의 구현에 관한 연구로 8개의 심볼 오류까지 정정 가능하다. 오증 계산은 16개의 오증 계산셀로 구성되어 지며, 오류 위치 다항식을 계산하는데 있어서는 Berlekamp-Massey 알고리즘을 사용한다. VHDL로 설계되어 Synopsys를 이용하여 검증 및 합성하였다.

• Journal of the Korean Society of School Health
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• v.4 no.2
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• pp.176-192
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• 1991

School nurses, in service of 102 special schools in Korea, were urveyed by mail questionnaires from February to March, 1991 and 77 of hem responded. Collected data were analyzed to establish the direction of health management in special school and to provide basic reference data for improving the quality of the management of school-nurses' services. The major findings are as follows: Out of special schools surveyed, 67.5% is private school and 83.2% is located in city. The average number of classes, students, and educational personnels per special school is 17.2, 194, and 28 respectively. The average age of school-nurses surveyed is 32.7. The proportion of graduates from the junior college and upward was 97.4%, the proportion of the married was 71.4%. Out of respondents, 71.4% has religion : 79.2% has past career in the fields of clinics or public health: 62.3% accompanishes independent services: 77.9% belongs to primary school. About 69% of nursing room in special schools surveyed is located at the first floor. Out of special school surveyed, 90.9% has no organization for school health programms: Only 18.2% entrusted everyone of school doctor, school dentist, and school pharmacists with school health. 46.8% of respondents didn't know about the annual budget for school health programmes. The average annual expenditure for school health programme per special school was 317,000F26. won and the purchase cost for medical supplies accounted for the larger part of them. The monthly average number of students utilizing school nursing room was 71 per school, annual utilization times of school nursing room was 4.4 per student and utilization due to injury was prevalent by 26.6% and there is some differences in using the school nursing room according to disabled area. Rate of referral to medical facilities was 1.4%. The leading reason of referral to medical facilities was high fever among those who have visual handicaps, fracture among those who have emotional disturbance, injury by trauma among others. Nine hundred fifty six students of students in special school surveyed have sufferd from epilepsy and prevalence rate of epilepsy was 6.4%. Only 22.6% of respondents replied that they had physical examination more than 2 times per year. Out of respnodents, 98.7% answered that they had health education and 67.1% of them ansered that they educated in a classroom, 98.7% of respondents emphasized need of sex education. Respondents put the most emphasis on the personal hygiene when they performed health education and they used broadcasting education in the area of visual handicaps, OHP or VTR in hearing handicaps, home correspondence or OHP VTR in other area importantly. About 47% of repondents answered that health education was the most difficult and they emphasized that definite guide on health management was requested. Respondents had self-confidence and high perfomance rate in most of school-nurses' services completely, but so they was not in area of evaluation of school health programmes, an examination of physical strength, evaluation of health education, management of school purification area, suture of wounds. In consideration of above findings, we may conclude that special education for school-nurse in special schools as well as improvement of definite guiding principles are requested to establish direction for health management in special schools and to improve the degree of quality for school-nurses' sevices in special schools.

• Journal of the Korean Society of School Health
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• v.15 no.2
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• pp.205-218
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• 2002

Objectives : Because elementary school children are sensitive and prevalent to dental caries, oral health care program for the elementary school children (ESOHCP) should be met the first priority for the national oral health care program. This study was performed to proposed the guidelines for executing the efficient ESOHCP through the evaluation of present oral health care and education status based on the attitudes and opinions of health teachers. Methods : Subjects were 181 health teachers those are a part of the total 273 elementary school health teachers in Busan. From April to June 2001, questionnaire survey on the teacher's attitude and opinion, present status of oral health care and education in their own school was done. Data was analyzed by $\chi^2$-test, t-test, ANOVA using SAS (ver 6.21) program. Results : Mean age of the teachers was 40 years (24~58 years) and mean scale of the subject school was 32 classes (5~58 classes). Above 90% of them agreed with the necessity and importance of ESOHCP, but actual level of concerning was lower. They gained the informations about oral health mainly from media (33%), PC net (26%), academic society (25%), and more used internet (p=0.012) in younger generation. Though most of them (96%) had a specified school dentist, only 58% had the experience of periodic oral health examinations in their own school. The major experienced ESOHCP was fluoride brushing and contest to choose the best healthy teeth. Oral health education given by the teachers was not professional but their own. About half (42%) of the teachers had never taken education during last one year. Major education materials were VTR tape (79%), teeth model (64%), CD (55%), booklet (50%), etc., and the teachers' preference was also VTR tape (43%) and CD (41%). When they need education materials, they frequently request to dentist's association (36%), academic society (35%), but rarely to dental clinics or dentists (6%). They prefer that two times (46%) of annual oral health education, with the contents of regular brushing (53%), but lower regular visit to clinics (13%). The interest to oral health care (p=0.016) increased with teacher's age. And, they agreed regular students education in case of higher interest(p=0.044). Intention about join in the model school program was decreased with scale of school (p=0.002). Conclusions : This result showed that the present status of ESOHCP is still insufficient. It considered that the health teachers' interest and role is most important for the maintenance and success of ESOHCP. The professional and efficient education program would be focused on the health teachers to induce drive on ESOHCP.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.2 no.1
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• pp.10-19
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• 1992

Mn - Zn Ferrite has physical properties of the high initial permeability, saturation magnetic flux density, and low loss factor as a representative magnetic material of soft ferrites, in addition the mechanical property is excellent as a single crystal. Therefore it is important electronic components and used for VTR Head. Mn - Zn Ferrite single crystals with the diameter 8mm were grown in atmosphere mixed with $O_2$ and Ar gas by the Floating Zone(FZ) method that impurities can not be incorporated to the crystals because of not-using the crucible to put in the melt, and the sharp temperature gradient results from making a focus at one point utilizing the infrared ray emitted from the halogen lamp as a heat source. During the crystal growing, the highest temperature of melting area was maintained to be $1650^{\circ}C$, growth rate and rotation rate were 10 mm/hr, 20 rpm respectively. The phases and the growth directions of crystals were determined from the analysis of X RD patterns, Laue, TEM diffraction patterns and etch pit shapes were observed by the optical microscope through the chemical etching. The corelation of optimum conditions for acquiring the better crystals was found out with the growth rate, the length and diameter of melt at the interface according to the diameter of feed rod, and the patterns of growing interface also studied.