• 한국기계가공학회지
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• 제20권4호
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• pp.80-86
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• 2021

Plastics are widely used in mechanical and other fields due to their light weight, design flexibility, and molding processability. In processing plastics, defective products are mixed and reprocessed to improve production efficiency and reduce costs. In this study, an experiment was conducted to confirm the coefficient of thermal expansion of HDPE during this reprocessing. The coefficient of thermal expansion was measured at different measurement directions and heating rates. As a result, we observed that the coefficient of thermal expansion in the direction perpendicular to the injection direction is greater than that in the horizontal direction.

• 생물환경조절학회지
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• 제30권1호
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• pp.27-36
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• 2021

정전용량 수분측정 센서는 수경용 배지 양쪽에 구리 및 테플론으로 절연된 전극판(30cm×10cm)을 부착하여 배지의 넓은 부분에 걸쳐 측정하도록 개발되었다. 본 연구는 콘덴서형 정전용량 센서로부터 출력되는 정전용량 값을 배지 함수량으로 변환하는 것이다. 정량화 실험은 양액을 공급하면서 배지 물무게와 정전용량 변화를 측정하고 그 값을 비교하는 방식으로 수행되었다. 배지 함수량과 정전용량은 본 연구를 위해 특별히 개발된 소프트웨어와 함께 센서와 로드셀을 사용하여 20~30초마다 측정되었다. 상용 curve-fitting 프로그램을 이용하여 배지 함수량과 정전용량을 변수로 정전용량 값으로 배지 함수량을 추정하였다. 공급하는 물의 양이 증가하면 정전용량도 증가하는 경향을 보였다. 배지 내 물무게에 따른 정전용량에 대한 변동계수(coefficient of variation, cv)는 배지 내 물무게가 1.0kg 수준에서 다른 무게에 비해 높아 함수량 보정은 물무게를 1.7~6.0kg 수준에서 수행하였다. 정전용량과 물무게 사이의 상관 계수는 0.996이었고 보정식에 의해 정전용량으로 추정된 함수량은 로드셀로 측정한 배지 함수량과 비교하였다.

• International Journal of Industrial Entomology and Biomaterials
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• 제1권1호
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• pp.25-28
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• 2000

A comprehensive study on daily pupal weight loss due to histolysis and histgenesis in Bombyx mori Linn., has been undertaken. The percentag of pupal weight loss in the male pupa is higher than the female, conforming that the female pupa require more energy in the form of less pupal weight loss for ovipositional activities. The regression equation clearly shows higher percentage loss of daily pupal weight in male than female with respect to age and, this is also evident from the slope of the regression line. Moreover, analysis of the coefficient of correlation shows that the weight loss of pupa is directly correlated with the age rather than climatic parameters under which the pupa dwells.

• 한국조사연구학회지:조사연구
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• 제7권2호
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• pp.53-69
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• 2006

표본조사에서 가중치는 설계 단계와 분석 단계에서 만들어지고 부여될 수 있다. 설계 단계의 가중치는 추출확률이나 응답률 등과 같은 표본 데이터 획득 지표에 관련되어 있고 분석 단계의 가중치는 모집단 수치나 다른 보조 변수정보 등과 같은 외적인 정보와 관련되어 있다. 그리고 최종가중치는 설계 단계의 가중치와 분석 단계의 가중치의 곱으로 만들어진다. 이 논문에서는 분석 단계에서 부여되는 가중치에 초점을 맞추어 가중평균으로 모평균을 추정할 때 가중평균에 포함된 가중치가 모평균 추론에 미치는 영향을 고찰하였다. 유한모집단에서 각 조사단위에 조사변수와 가중치가 쌍으로 있고 표본추출확률이 균등한 경우를 가정하였다. 이러한 조건에서 가중평균의 편향과 평균제곱오차를 구하여 가중평균은 모평균의 편향 추정량임을 보였고, 편향의 방향과 크기는 조사변수와 가중치의 상관관계로 설명할 수 있음을 보였다. 즉, 만일 가중치와 조사변수가 양의 상관관계가 있으면 가중평균은 모평균을 과대 추정하게 되고, 만일 음의 상관관계가 있으면 모평균을 과소 추정하게 된다. 그리고 두 변수의 상관계수가 크면 편향은 증가한다. 가중평균에 대한 이론적인 수식 유도와 함께 편향의 크기와 평균제곱오차의 크기를 수치적으로 검토하기 위하여 모의실험을 실시하였다. 모의실험에서는 상관계수가 -0.2과 0.6사이에 있는 9개의 가중치를 생성하였고, 표본수는 100부터 400까지 고려하여 편향의 크기와 평균제곱오차의 크기를 수치적으로 구하였다. 하나의 결과로써 상관계수가 0.55이고 표본수가 400인 경우에 가중평균의 편향의 제곱이 평균제곱오차에서 차지하는 비율은 무려 82%에 이르는 것으로 나타났는데, 이는 가중평균의 편향이 어떤 경우에는 매우 심각할 수도 있음을 보여주는 것이다.

• 한국농공학회논문집
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• 제58권6호
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• pp.39-45
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• 2016

In this paper, analyzes the characteristics of self-weight consolidation on the dredged clay according to the fines content and falling height. Research was performed with the dredged clay sampled by Sae-mangeum field site. Classification of fines content was performed by sieve analysis test. After adjusting the fine content, self-weight consolidation tests were carried out focussing on the variation of fines content and falling heights. From the test results of the self-weight consolidation test, samples with high fines content had reached sedimentation completion more later than ones with less fine content samples. In other words, the start of self-weight consolidation was slowing down with increasing of fines content. Also, from the test results of calculating the coefficient of sedimentation consolidation, the coefficient value were increased with the fines content increases. In addition, the change of sedimentation ratio and volume ratio showed more higher changed value as the fine content increases. Thus, it is important to consider the fines content when estimate the settlement time of dredged soil in field dredge work.

• 한국의류학회지
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• 제6권1호
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• pp.17-26
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• 1982

This article aims to determine the interrelation among exfoliation strength, the repeated laundry number, the coefficient of friction and the cover factor about the fusible interlining produced by using different amount resin. The practicality of stiffness and warmth of the fusible interling were examined. The results are summarized as follows: 1) As a factor that affecting the exfoliation strength of fusible interlining, the coefficient of friction and the cover factor about the fusible interlining produced by using different amount resin. (2) Regardless of the weight of the resin, the exfoliation strength of fusible interlining declined gradually as the repeated laundry number increased. This tendency arises much more in the case of the filament yarn fabric than in that of the spun yarn fabric. The stability of the exfoliation strength was better, regardless of the increase of the repeated laundry number, when the weight of the weight of the resin was 10 g/$m^2$. (3) The spun yarn fabric, which has more fuzz than the filament yarn fabric, is more suitable for the fabric of fusible interlining. The smaller the cover factor difference between the face cloth and the interlining cloth, the stronger the exfoliation strength. (4) When the stability of the shape is a necessary factor in the consumption of the fusible interlining, a resin weight of 20 g/$m^2$ is the most suitable; however when stiffness and warmth are necessary factors, a resin weight of 10 g/$m^2$ is the most suitable.

• 대한지역사회영양학회지
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• 제12권3호
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• pp.361-371
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• 2007

The purpose of this study was to assess the daily steps, physical activities and activity coefficient of the elementary school children in the rural area. Body weight, height and daily steps were measured and one-day activity diaries were collected by interviewing children. The average age of the subjects was $9.96{\pm}1.02$ years. Average height, weight, obesity index, body fat and muscle of subjects were $136.2{\pm}8.9cm,\;35.2{\pm}8.5kg,\;99.6{\pm}18.8%,\;22.9{\pm}8.5%\;and\;35.8{\pm}6.0%$, respectively. The average daily steps of the subjects was 17,584 and daily steps (19,314) of 3rd grade students was significantly higher than that (15,712) of 5th grade children. But there was no significant difference in daily steps and activity coefficients between boys and girls. Daily steps (23,347) of exercise group showed the significantly higher than that (16,144) of non-exercise group. Gender and grade of subjects did not have significant influence on activity coefficients, but there was a significant difference in activity coefficient on weekdays between the exercise group ($1.82{\pm}0.30$) and non-exercise group ($1.50{\pm}0.21$). Analysis of variance revealed stronger associations between daily steps and body fat (%) than between daily steps and BMI. Daily steps showed significant negative correlation with body fat (%) measured using two methods r=-0.321 and r=-0.365, respectively. Activity coefficient was significantly correlated (r=0.436) with daily steps, thus increasing daily steps cm prevent and treat childhood obesity by increasing the energy expenditure. The higher activity coefficients (weekday 1.56, weekend 1.53) of the subjects was caused by the fact that rural students spent more time outside and enjoyed stronger activities than urban students. The results of this study can be used to estimate energy requirements for Korean children based on exercise levels and living areas.

• 동력기계공학회지
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• 제17권6호
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• pp.88-94
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• 2013

As the results of analysis that are applying a heat pump using underground water as heat source of facility horticulture house, temperature change in house, growth of cultivated plants and the crop characteristic, the conclusion can be acquired as follows. It was possible to maintain the chamber temperature through operating heat pump with setting goal temperature at $16^{\circ}C$ and temperature variation at ${\pm}3^{\circ}C$. And cooling and heating coefficient of performance in heat pump system are different from setting room temperature and operation condition of equipment, totally in case that the setting temperature in house is low, the coefficient of performance and the in case that temperature departure is low. In case that the house does not heated, the result of the growth characteristic of cucumber planted last 50days is that cucumber grown in house equipped with heat pump is the most favorable growth characteristic due to maintaining a constant room temperature. After 90 days, the quantity and weight cucumber harvested in each house are averagely 9.8%, 13.1% increase and more heavy weight respectively. So it is researched that crop characteristic is superior.

• Journal of the Korean Data and Information Science Society
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• 제25권2호
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• pp.357-363
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• 2014

타자들의 타격능력을 나타내는 OPS를 계산할 때 출루율을 단순하게 장타율과 더한다. 하지만 실제로 출루율에 가중치를 부여하여 계산한 OPS가 게임당 평균득점과 상관관계가 더 커지게 되는데, 본 연구에서는 한국프로야구에 있어서 가장 적합한 가중치를 전체 데이터 및 연대별 데이터를 이용하여 추정하였다. 제안된 가중치는 게임당 평균득점의 영향을 받으며, 가중치와 게임당 득점과의 관계는 회귀직선으로 설명하였다.

• 대한가정학회지
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• 제23권3호
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• pp.9-16
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• 1985

There are two standards for evaluation of fabric aesthetics, the feeling of fabric and the fabric sense of sight. Its drapalility with lustre is one of factors to decide the fabric sense of sight. This study was carried out to investigate the drape property property of fabrics. The fabric characteristics and the physisical properties of fabrics were tested. And the effect of the laundering on the drape properties was examined. RESULTS : 1. The drape coefficients of sampled fabrics were increasd as the thickness of fabrics were increased, excluding the fabric consisting of 60% polyester$\times$40% wool. 2. The drape coefficient of sampled fabrics were decreased as the cover faders of fabrics were increased, excluding the summer clothes and the fabrics of 100% wool. 3. The drape coefficients of fabrics other than sumer clothes were increased as the weight of fabrics were in creased. 4. Positive correlation was observed between the stiffness and the drape coefficient. 5. Negative correlation was observed between the fabric shrinkage and the drape coefficient. 6. The drape coefficient was decreased to a certain limit by laundering.But as the laundering was repeated up to certain number, the drape coefficient and the node number, a significant correlation was observed between the drape coefficient and the node shape.