• 전자공학회논문지A
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• 제33A권10호
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• pp.71-80
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• 1996

Sattering problem of electromagnetic waves by periodic strip grating with two dielectrics over a ground plane in case of oblique incidence and arbitrary polarization is analyzed by the vector floquet mode expansion method and the moment mehtod from the viewpoint of soft and hard boundary value problem. To confirm proposed analysis methods, we examine the solution convergence for the scattering problem. And some numerical results of artificially soft and hard surfaces using the structure filled with single dielectric slab between periodic strip grating and gorund plane is compared with previous results. Some interesting results for soft and hard surfaces using periodic strips loaded with two layered dielectric slabs over a ground plane are given.

• The Journal of Korean Physical Therapy
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• 제27권1호
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• pp.7-11
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• 2015

Purpose: This study was conducted in order to determine the effects of knee malalignment including genu varum, valgum, and recurvatum on static and dynamic postural stability. Methods: A total of 80 subjects were enrolled in this study. Subjects who showed over 3 cm in the distance between the knees were classified as the genu varum group, and subjects who showed over 3 cm in the distance between the ankles were classified as the genu valgum group. Subjects who showed over 1 cm in the distance between the patella and a table in prone position were classified as the genu recurvatum group. Static and dynamic stability were measured as overall, anterioposterior, and mediolateral balance index using a Biodex Balance System. Results: This study showed that knee alignment affected static and dynamic postural stability. In particular, there were significant differences in the mediolateral stability index among genu varum, valgum group, and the other groups, but no differences in overall and anteriolateral stability index. Significant differences in the anterioposterior stability index were observed between genu recurvatum and the other groups, however, there were no differences in overall and mediolateral stability index. Conclusion: The findings were that knee malalignment affects postural stability toward a specific direction. Treatment to improve postural stability for treatment of knee malalignment or to prevent falling or injuries is needed and postural stability toward a specific direction according to the knee alignment conditions should be considered.

• Animal Bioscience
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• 제34권4호
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• pp.759-769
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• 2021

Objective: This study aimed to investigate the effect of stocking density on the behavior, productivity, and metabolism of periparturient Holstein cows as well as calf performance. Methods: A total of 48 periparturient cows were randomly assigned into three groups at 28 days (±3 days) before their expected calving date. The stocking densities of the groups, relative to the standard cubicle and feed bunk number, were i) 80% (13 cows), ii) 100% (16 cows), and iii) 120% (19 cows). Lying and rumination behavior was recorded using electronic data loggers and HR-Tags from d -21 ("d-" means days before calving) until the calving date, d 0. Lying time was assessed to determine the diurnal total hours spent lying per day. Rumination time was averaged in 2 hours interval periods over 24 hours during the experimental period. Results: Cows in the 80% group spent more time lying and ruminating between d -21 and d -7 and tended to ruminate more between d -14 and d 0. Calcium levels tended to be higher for cows in the 80% group, no other observable differences were found in monitored blood parameters. Moreover, 3.5% fat corrected milk and energy corrected milk yields were higher in 80% group in the first month of lactation. No other observable differences were found in the yield and composition of colostrum and milk in the first 10 months of lactation. The growth and performance of calves in the first week of life was not affected by stocking density of the dams. Conclusion: We concluded that lower stocking density may increase lying and ruminating behavior of prepartum Holstein cows. However, this did not translate into improved productivity and metabolism.

• 한국지역사회생활과학회지
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• 제20권1호
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• pp.71-80
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• 2009

This study aimed to identify and compare variables affecting life satisfaction of older women by focusing on household types and poverty levels. The study used data from the Korea Longitudinal Study of Aging administered by the Korea Labor Institute in 2006. The data for 1,017 older women ages over 65 including 427 single households and 590 couple households was analyzed. First, interaction effects of household types and poverty levels on life satisfaction were statistically significant. For the non-poverty households of older women, there was no explicit difference between single households and couple households in life satisfaction, but for the poverty households, single households were lower in life satisfaction than couple households. Second, as a result of reviewing four groups of older women (poverty-single household, poverty-couple household, non-poverty-single household, and non-poverty-couple household), besides religion, it was found that there were significant differences in age, education level, number of children, health level, residence area, and status of economic activity. Third, when analyzing variables affecting life satisfaction, common predictors for the four groups were health level and ownership of house. Older women who perceived to be healthier and owned their own homes were higher in life satisfaction. For poverty-single households, older women with over middle school graduation were also higher in life satisfaction, but for poverty-couple households, older women with over middle school graduation and more children were higher.

• 조명전기설비학회논문지
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• 제27권2호
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• pp.84-94
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• 2013

In case when the existing TRIAC phase controlled dimmer is drove for the LED lighting equipments, there are many problems such as the LED flicker in low phase-angles, the acoustic noise and elements damage by increase of the peak voltage in the input filter capacitor, mulfunction by insufficiency of the TRIAC holding current, and the abnormal oscillation by LC resonant. In this paper, we proposes the single-stage quasi-resonant PSR(Primary Side Regulation) PWM converter, and the design, the simulation and experiment are performed. As a result, it could confirm that the proposed PWM converter is the lighting equipments for LED drive which can alternate the existing 60W class incandescent bulbs and it has the high drive performance of the efficiency 80% and over, the power factor 0.95 and over under the normal voltage 220V. Finally, total harmonic distortion(THD) is gratified with a standard[1] of the lighting equipments and the durability is evaluated as the high reliablilty of 150,000 hours and over.

• 한국안전학회지
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• 제11권3호
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• pp.81-88
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• 1996

In order to investigate the electrical properties of transformer oils for large power, the characteristics of AC and Impulse breakdown in gap length of 1.0~2.5mm and that of volume resistivity were researched in temperature range of 20~$100^{\circ}C$. An geometrical capacitance of electrode with coaxial cylindrical shape for measuring the volume resistivity was 16pF, and highmegohm meter with model no. VMG-1000 was used, and also the applied voltage were DC 100, 250 and 500V. In the dependance of breakdown characteristics due to electrode gap length, it was confirmed that breakdown voltage was nearly uniform by volume effect according to the increase of gap. In the characteristics for AC breakdown, the dielectric strength was increased to $90^{\circ}C$ but decreased over $90^{\circ}C$, and also in case of impulse breakdown, it was increased to 7$0^{\circ}C$ and at dated $70^{\circ}C$ over in temperature range. The calculated mobility of oils in the characteristics for impulse breakdown were about $10^{-5}$~$10^{-4}cm^2/V{\cdot}S$, and the value of volume resistivity was almost invariable in low temperature range, regardless of voltage by the stable thermal properties, and it indicated a peak at $50^{\circ}C$ and had a sudden change to decrease over that temperature, and also the value of volume resistivity in 250V/mm at $80^{\circ}C$ is suitable for the International electrical standards, it was confirmed.

• 한국산학기술학회논문지
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• 제14권6호
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• pp.2760-2766
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• 2013

서론 : 본 논문은 전방 잠금형 금속판을 이용한 요골 원위부 골절 수술 후 나사못(screw)의 요골구 관통 유무를 확인하기 위한 방법으로 방사선 요골구 접선방향촬영법의 새로운 검사법을 제시하고자 한다. 재료 및 방법 : 요골구 접선방향 촬영 시 요골 원위부 거상 각도는 2.5, 5, 7.5, 10도와 전완골과 방사선 검출기와의 각도를 60, 70, 80도로 각각 변화시켜 촬영한 방사선영상에서 나사못의 요골구 관통유무를 분석하였다. 결과 : 요골구 접선방향 영상에서는 요골구를 관통하지 않은 경우와 요골구 내관통, 요골구 외관통인 경우가 각각 55명(63.95%), 9명(10.47%), 22명(25.58%)으로 분석 되었고, 요골구를 관통한 나사못의 길이는 0.43~2.72mm의 범위로 평균 1.06mm이었다. 요골구가 잘 묘사되는 방사선 촬영법은 요골 거상각도 2.5~7.5도에서 90%이상, 전완골과 방사선 검출기의 각도 70도에서 요골구가 80%이상 잘 묘사되는 것으로 분석 되었다. 결론 : 요골구 접선방향 촬영법은 요골 원위부 거상 각도 5도, 전완골과 검출기의 각도는 70도를 추천 한다.

• 한국응용곤충학회지
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• 제50권4호
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• pp.289-293
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• 2011

파정식 초기 파총채벌레의 경제적피해허용수준을 설정하기 위하여 온실에서 파총채벌레 접종기간에 따른 파의 생육, 피해 및 수량을 조사하였다. 파 정식초기에는 파총채벌레 접종기간(즉 가해정도)에 따른 수량감소율은 5일, 10일, 15일, 20일 접종기간에서 각각 17.0%, 53.3%, 38.4%, 80.8%로 증가하였다. 파총채벌레 발생정도와 파 수량감소 관계를 구명하기 위하여 파총채벌레 누적밀도일(Cumulative Insect Days, CID)과 수량 감수량(%) 간 회귀분석을 실시한 결과 비선형식인 logistic 모형에 잘 적용되었다. 이 식으로부터 경험적인 수익한계(Gain Threshold) 5%와 통상적 상품화율(93%)를 감안한 수량 감소율 12% 수준에서 파총채벌레 경제적피해허용수준은 30 CID로 추정되었다. 또한 요방제밀도는 경제적피해수준의 80%가 되는 24 CID로 추정되었다. 본 결과는 더 개선된 모형이 개발될 때까지 파 생육초기 파총채벌레 관리에 유용하게 활용될 수 있을 것으로 판단되었다. 또한 파 노지포장에서 생육후기(정식 후 120일 접종) 파총채벌레 피해가 파 수량에 미치는 영향을 검토한 결과, 파 생육후기에는 낮은 밀도에서 오히려 수량이 증가하였고, 그 후 밀도가 더 증가함에 따라 수량이 감소하는 등 전형적인 보상적 반응(over-compensatory response)을 보였다.

• 한국지리정보학회지
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• 제15권3호
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• pp.119-136
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• 2012

본 연구는 IPCC(Intergovernmental Panel on Climate Change)에서 제시한 기후변화 취약성 개념을 서울시에 적용, 적정 홍수 취약성 지표 산정 및 퍼지모형을 활용하여 기후변화 분야 중 홍수취약성을 평가하고 GIS를 이용하여 취약성도를 작성하였다. 이를 위해 선행연구를 기반으로 지표를 도출하였다. 도출된 지표는 기후노출(일 최대 강수량, 일강수량 80m 이상인 날 수), 민감도(침수지역, 경사, 지질, 고도, 하천으로부터의 거리, 지형, 토양 및 불투수면적) 및 적응능력(홍수조절능력, 자연녹지, 공원녹지) 등의 자료이며, 이를 GIS 기반의 공간데이터베이스로 구축하였다. 구축된 지표값들을 통합하기 위한 방법으로 퍼지모형을 활용했으며, 퍼지소속값 결정을 위해서는 빈도비를 활용하였다. 2010년 침수 발생 자료를 활용하여 항목들간의 상관관계 및 퍼지소속값을 산정하였으며, 2011년 침수 발생 지역으로 작성된 취약성도를 검증하였다. 분석결과 서울지역 홍수피해에 크게 영향을 미치는 지표는 일강수량이 80mm이상인 날수, 하천과의 거리, 불투 수층으로 나타났다. 서울의 경우, 최대강수량이 269mm 이상일 때 적응능력(유수지, 녹지)이 부족하고, 고도가 16~20m 정도이며 하천에서 50m이내에 인접한 지역, 공업용지에서 홍수취약성이 매우 높은 것으로 나타났다. 지역적으로 영등포구, 용산구, 마포구 등 한강 본류의 양안에 위치한 구들이 비교적 취약지역을 많이 포함하고 있는 것으로 나타났다. 본 연구는 기후변화 취약성 평가의 개념을 적용하고, 방법론으로 퍼지모형을 활용함으로써 기존의 취약성 평가기법을 개선하였으며 평가결과는 홍수예방정책에 대한 우선지역 선정과 의사결정의 주요한 근거로 활용될 수 있을 것으로 기대된다.

• Journal of Animal Science and Technology
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• 제60권12호
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• pp.30.1-30.11
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• 2018

Background: Recently, as production costs have been increasing owing to rising feed prices worldwide, shortening the age of slaughter has been recognized as a way to increase farm income. In Korea, the raising period for Hanwoo steers is over 31 months with the delay of weaning and castration stated as one of the reasons for the increase in the raising period. Thus far, studies on age of weaning and castration have been conducted individually, and there have been no studies on the combined effects of weaning and castration ages on the growth performance and carcass characteristics in Hanwoo steers. Methods: Weaning ages were calculated at 80 or 130 days of age, and castration ages were calculated at 90 days and 180 days of age. Calves were allocated to one of the four treatment groups: W80C90 (weaning at 80 days of age and castration at 90 days of age), W80C180, W130C90, and W130C180. Results: For the entire experimental period, weaning and castration ages did not significantly affect growth performance of Hanwoo steers. In addition, weaning and castration ages did not affect the overall yield and quality traits of carcass in Hanwoo steers. Conclusion: Weaning and castration ages had small effects on growth performance and carcass characteristics in Hanwoo steers. Therefore, the early weaning and castration ages are recommended to reduce the slaughter age without any negative effects on meat quality grade.