• Journal of the Korean Society of Manufacturing Process Engineers
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• v.20 no.4
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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.

• Journal of Bio-Environment Control
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• v.30 no.1
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• pp.27-36
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• 2021

A capacitive water sensor was developed to measure the capacitance over a wide part of a substrate using an insulated electrode plate (30 cm × 10 cm) with copper and Teflon attached on either side of the substrate. This study aimed to convert the capacitance output obtained from the condenser-type capacitance sensor into the substrate water content. The quantification experiment was performed by measuring the changes in substrate water weight and capacitance while providing a nutrient solution and by subsequently comparing these values. The substrate water weight and capacitance were measured every 20 to 30 seconds using the sensor and load cell with a software developed specifically for this study. Using a curve-fitting program, the substrate water content was estimated from the output of the capacitance using the water weight and capacitance of the substrate as variables. When the amount of water supplied was increased, the capacitance tended to increase. Coefficient of variation (CV) in capacitance according to the water weight in substrate was greater with the 1.0 kg of water weight, compared with other weights. Thus, the fitting was performed with higher than 1.0 kg, from 1.7 to 6.0 kg of water weight. The correlation coefficient between the capacitance and water weight in substrate was 0.9696. The calibration equation estimated water content from the capacitance, and it was compared with the substrate water weight measured by the load cell.

• International Journal of Industrial Entomology and Biomaterials
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• v.1 no.1
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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.

• Survey Research
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• v.7 no.2
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• pp.53-69
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• 2006

Weights can be made and imposed in both sample design stage and analysis stage in a sample survey. While in design stage weights are related with sample data acquisition quantities such as sample selection probability and response rate, in analysis stage weights are connected with external quantities, for instance population quantities and some auxiliary information. The final weight is the product of all weights in both stage. In the present paper, we focus on the weight in analysis stage and investigate the effect of such weights imposed on the weighted mean when estimating the population mean. We consider a finite population with a pair of fixed survey value and weight in each unit, and suppose equal selection probability designs. Under the condition we derive the formulas of the bias as well as mean square error of the weighted mean and show that the weighted mean is biased and the direction and amount of the bias can be explained by the correlation between survey variate and weight: if the correlation coefficient is positive, then the weighted mein over-estimates the population mean, on the other hand, if negative, then under-estimates. Also the magnitude of bias is getting larger when the correlation coefficient is getting greater. In addition to theoretical derivation about the weighted mean, we conduct a simulation study to show quantities of the bias and mean square errors numerically. In the simulation, nine weights having correlation coefficient with survey variate from -0.2 to 0.6 are generated and four sample sizes from 100 to 400 are considered and then biases and mean square errors are calculated in each case. As a result, in the case or 400 sample size and 0.55 correlation coefficient, the amount or squared bias of the weighted mean occupies up to 82% among mean square error, which says the weighted mean might be biased very seriously in some cases.

• Journal of The Korean Society of Agricultural Engineers
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• v.58 no.6
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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.

• Journal of the Korean Society of Clothing and Textiles
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• v.6 no.1
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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.

• Korean Journal of Community Nutrition
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• v.12 no.3
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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.

• Journal of Power System Engineering
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• v.17 no.6
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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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• v.25 no.2
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• pp.357-363
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• 2014

OPS is a sabermetric baseball statistic calculated as the sum of a player's on base percentage (OBP) and slugging percentage (SLG). One of the frequently cited problem with OPS is that OPS gives equal weight to its two components, OBP and SLG. In fact, OBP contributes significantly more to scoring runs than SLG does. This paper provides some exploration into the correct weighting of OBP to SLG when adding the two together. By correlating different coefficients of OBP to runs scored per game, the weighted OPS that weighting OBP 56% in two place more than SLG produced the highest correlation. We found that the weight of OBP increases as RPG increases. Also we suggest the linear regression equation of the best OBP coefficient against RPG.

• Journal of the Korean Home Economics Association
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• v.23 no.3
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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.