• Journal of the Korean Society for Precision Engineering
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• v.17 no.6
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• pp.17-24
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• 2000

1960년 Jawan 등이 1.15㎛ 파장을 포함한 6개의 발진파장을 갖는 He-Ne 레이저의 연속 발진을 성공시킨 이후 레이저는 단색성이나 빛의 진직성을 이용하는 계측에서 특히 정밀길이측정에서 매우 중요하게 사용되고 있다. He-Ne 레이저의 발진선폭은 80㎑로써 길이표준기로 사용되었던 Kr-86 스펙트럼선의 선폭(400㎒)의 5,000 분의 1에 해당되는 매우 좁은 선폭을 갖고 있다.(중략)

• 전기의세계
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• v.16 no.1
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• pp.65-67
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• 1967

최근 전력수요의 급속한 증가는 전력기기 생산업체의 실력을 Test 할 절호의 기회를 만들어 주었다. 한영공업의 변압기는 송배전용, 또는 공업용으로 널리 쓰이는 용량 500-30,000kVA, 전압 154KV이하의 내철형을 표준품으로 제작하고 있다. 이런 정도의 용량의 변압기로서는 구조가 간단한 내철형이 중량도 가볍고, 표준화가 용이하며, 충격절연내력도 표준절연내력 자체가 그리 크지 않은데다, 구조상 내부전위진동 주기도 짧으므로 충분히 이것에 견디는 강도를 갖인것을 경제적으로 제조가능하다. 한영공업의 내철형변압기는 과거 80년 이상의 경험을 가진 세계적 제작업자인 Westinghouse의 기술지도와 엄선한 외국자재로서 고도의 신뢰성을 갖는 전력용변압기를 공급하게 된것이다.

• Elastomers and Composites
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• v.47 no.1
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• pp.9-17
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• 2012

Herein, life time prediction based on the deterioration of physical properties of chloroprene rubber (CR)aged by heat and seawater was performed. CR samples were experienced an accelerated test at $80^{\circ}C$, $100^{\circ}C$, $120^{\circ}C$ for heat aging, and $40^{\circ}C$, $60^{\circ}C$, $80^{\circ}C$ for seawater aging for 20,000 hrs. The change in tensile strength, maximum elongation,hardness was measured. As a result, the decrease in elongation was a major factor causing failure. The life time estimated using an Arrhenius model was 125 years at $23^{\circ}C$ for thermal aging and 9 years at $23^{\circ}C$ for seawater aging. SEM and elemental analysis reveal that cracks were generated and the content of oxygen was increased for CR agined by seawater. FT-IR spectrum shows the new C-O and C = O bonds were generated by the chemical reaction with seawater. Also, the glass transtion temperature was increased and the thermal decomposition was decreased by seawater aging.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.25 no.1
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• pp.37-44
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• 1992

Annual biomasses of small yellow croaker, Pseudosciaena polyactis, were estimated by biomass-based cohort analysis (Zhang, 1987) , using data on annual catch in weight at age for 1970-88 in Korean waters. Annual biomass of croaker was highest in 1974 with about 100,000 mt, declining to a level of 20,000-30,000 mt after 1981. Adult biomass also showed a peak in 1974 with about 50,000 mt. Afterwards, however, it continuously dropped. According to the estimates of biomass at age obtained from this analysis, the age composition of small yellow croaker in the 1980's differed greatly from that in the 1970's. The proportions of older croakers (>5 years) were very low in the 1980's and even the biomasses of young croakers (1-4 years) were at a very low level in the 1980's. Year classes of 1968, 1972 and 1978 appeared to be relatively dominant. The mean value of instantaneous fishing mortality (F) in the 1980's was twice that of the 1970's. Recruitment of croaker exhibited an unusally linear relationship with adult stock biomass.

• Clinical and Experimental Pediatrics
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• v.46 no.8
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• pp.769-776
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• 2003

Purpose : The survival rate of very low birth weight infants(VLBWI) has improved by virtue of specialized neonatal care. This study was performed to analyze the changes in incidence, survival rate and morbidity of VLBWI who admitted to Chonnam National University Hospital from 1996 to 2001. Methods : We enrolled 565 VLBWI, and compared the incidence and the survival rate according to the birth weight or gestational weeks between period I(1996 to 1998) and period II(1999 to 2001). The mortality rate according to the postnatal age, cause of death, morbidity and days of hospital stay were also compared. Morbidity is categorized into 'short term' which is curable until discharge, and 'long term' causing any types of sequelae after discharge. Results : Incidence of VLBWI significantly increased in period II over period I(6.0% vs. 11.0%, P< 0.001). The survival rate also increased in period II(71.8% vs. 80.1%, P<0.05), especially in 1,000 to 1,249 gm of birth weight(P<0.001) and in 28 to 30 weeks of gestation(P<0.001). The most common cause of death was respiratory distress syndrome in period I; however it was sepsis in period II. Although overall and short term morbidity rate increased, long term morbidity and days of hospital stay didn't increase in period II. Conclusion : Although the incidence of VLBWI significantly increased and the survival improved in period II compared to period I, especially in 1,000 to 1,249 gm of birth weight and 28 to 30 weeks of gestation, 'long term' morbidity rate and hospital days didn't increase.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 2002.07a
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• pp.78-83
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• 2002

2000년 현재 우리나라 농가의 트랙터 보유대수는 총 191,000대로 이 중에서 40, 50마력 급 이하는 165,000대로 대부분을 차지하고있으며 이러한 중소형 트랙터는 대부분 트랙터 클러치의 조작을 링크시스템으로 한 기계식 클러치이다. 오늘날 농가인력은 고령화가 심화되어있고 또한 부녀자의 영농참여 비중이 높아지고 있는 실정이며, 나아가 인체공학 등을 포함시킨 농업기계기술개발이 중요시되고 있는 실정이다. 오늘날 우리나라 농가에 보급된 농업기계는 대부분 남성을 대상으로 설계되어 있어 여성이 조작하기에는 어려운 점이 많으며, 특히 트랙터인 경우 기계식 클러치에서 농업 여성의 80%정도가 조작할 수 없는 것으로 보고된 바 있다. (중략)

• 한국해양학회지
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• v.22 no.2
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• pp.80-86
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• 1987

Five species of marine cladocerans, Evadne nordmanni, Evadne tergestina, Podon leuckarti, Podon polyphemoides and Penilia avirostris, were found in Chinhae Bay during the years 1982-1983. Incidence of E. nordmanni(April-May) in spring and of E. tergestina(June-December), E. avirostris(June-November) in summer through autumn was noticed during the present study. But P. polyphem oides appeared throughout the year except February. P. avirostris was the most abundant species(21,491indiv./㎥), followed by P. polyphemoides and E. tergestina. Population of E.normanni and P. leuckarti was extremely poor and recorded to be less than 1,000indiv./㎥. Seasonal change in size composition was noticed in E. tergestina and P. avirostris. Increase of length was recorded in P. polyphemoides when water temperature lower than 15$^{\circ}C$.

• Journal of Korean Ophthalmic Optics Society
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• v.11 no.3
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• pp.231-240
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• 2006

This study conducts a questionnaire survey of 492 middle school students in Jeju islands about the rate of using glasses/contact lens, the place and time of visual acuity test, the period of changing the glasses, the purchase price, the mason to change the glasses, the interrelationship between wearing spectacles and residential district, etc. The results are as follows: 1. 45.33% of the object of investigation use the glasses or contact lens to correct their visual acuity. Among them, the student who wears only glasses is 93.27%, the student who wears glasses and contact lens together is 5.83%, the student who wears only contact lens is 0.90%. 2. As for the period of changing his(her) glasses, below 6 month is 20.18%, from 6 month to one year is 52.02%, from one year to two years is 20.18% and more than two years is 7.62%. 3. As for the purchase price to change his(her) glasses, below 30,000won is 13.45%, from 30,000won to 50,000won is 43.50%, from 50,000won to 70,000won is 23.77%, from 70,000won to 100,000won is 15.25% and more than 100,000won is 4.03%. 4. As for the reason of changing his(her) glasses, cause of change of visual acuity is 55.16%, by broken frame and lens is 27.35%, as want to just change his(her) spectacles is 14.80% and as the others is 2.69%. 5. As for the relative importance in purchasing glasses, the student who thinks more frame is 16.59%, the student who thinks more lens is 67% and the student who thinks both frame and lens is 58.74%. 6. As for the frist time of visual acuity test, 1 grade of elementary school is 37.2%, 3 grade of elementary school is 12.56%, 4 grade of elementary school is 11.66% and 6 grade of elementary school is 11.66%. 7. As for the place of visual acuity test to determine the Dptr. of glasses which wear now, opitican's shop is 57.85% and ophthalmic clinic is 42.15%. 8. As for the frist time of wearing the glasses or contact lens for correct his(her) visual acuity, the most of answer(21.97%) is at 6 grade of elementary school. 9. As for the reason why does not wear the glasses or contact lens though his(her) naked binocular vision is below 0.8, as does not feel any difficulty in daily life is 62.5%, as know that the more wear, the more decrease his(her) visual acuity is 15.65%, by economical circumstance is 6.24% and as not good externally is 15.63%, respectively.

• Journal of dental hygiene science
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• v.6 no.3
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• pp.187-192
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• 2006

The purpose of this study was to delve into the factors associated with the oral health promotion behaviors of college students. The subjects in this study were 453 students who attended three different colleges in Gyeonggi province. After a survey was conducted, the collected data were analyzed with SPSSWIN 12.0 program. The findings of the study were as follows: 1. Concerning the basic oral health care of college students, 54.1 percent had ever visited dental clinics over the last year, and 53.4 percent hadn't received any preventive treatment during the same period of time. 2. As to their self-perception of oral health status, 80.1 percent didn't find themselves to be in good oral health. 3. Regarding the influence of their general characteristics, their self-efficacy was statistically significantly different according to their gender (p = .022). Their control of oral health varied statistically significantly with their major(p = .000), and whether or not they smoked (p = .004) made a statistically significant difference to that as well. Their oral health knowledge differed statistically significantly with their gender (p = .000), major(p = .000) and age group(p = .000), and whether or not they smoked(p = .006) made a statistically significant difference to that as well. 4. As for correlation among the variables, better oral health promotion behaviors were found among those whose self-efficacy was higher, whose control of oral health was better and who had more knowledge on oral health. 5. Preventive treatment, control of oral health and self-efficacy were identified as the variable that affected their oral health promotion behaviors.

• Korean Journal of Soil Science and Fertilizer
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• v.40 no.6
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• pp.495-500
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• 2007

Recently we are interest in organic farming of rice. The technology of paper mulching was practised without herbicide in machine transplanting cultivation of paddy. A field experiment was conducted in Gangseo series (coarse loamy, mixed, nonacid, mesic family of Aquic Fluventic Eutrochrepts) at the National Institute of Crop Science (NICS), RDA, Suwon, Gyeonggi province, Republic of Korea in 2004. This experiment was carried out to evaluate soil redox potential, weed control and rice growth by the different organic matter in paper mulching transplanting. Compost, rice straw and soiling rye were incorporated as organic matter. The nitrogen amount of controlled-release fertilizer (CRF) plot was 80% compared with nitrogen amount ($110kg\;ha^{-1}$) of conventional fertilization. Mulching paper consisted of recycled paper which was coated with biodegradable plastics. There were no difference between conventional rice transplanting and paper mulching on missing hills after organic matter application. Weed control were the highest at added soiling rye plot. The redox potential of soil was the lowest in rice straw + CRF 80% plot at tillering stage. The $NH_4{^+}-N$ in soil was the highest at soiling rye + CRF 80% tillering stage. There was no difference in yield between soiling rye + CRF 80%, compost + CRF 80% and conventional fertilization plot.