• 대한전기학회논문지
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• 제37권5호
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• pp.289-297
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• 1988

In this paper, the analysis of a generating torque characteristics of 2-phase induction motor driven with the phase control method is presented. The generating torque equations which represent average torque and pulsating torque are derived from the elementary machine model. The calculating equations which can get the values of average torque and pulsating torque is expressed by the parameters of the equivalent circuit of 2-phase induction motor. According to the calculating equations, these performance characteristics are investigated under various conditions. Finally, a strategy to eliminate non-linearity and pulsating torque generated in driving 2-phase induction motor with the phase control method is presented.

• 상하수도학회지
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• 제22권3호
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• pp.299-306
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• 2008

This study has been conducted to derive the bio-energy, hydrogen and methane production, from mixture of food wastewater and swine wastewater, the high strength organic wastewater and to increase effluent quality. To overcome this limitation in one-phase anaerobic process, two-phase anaerobic process combining hydrogen fermenter and methane fermenter was applied. In this system $2,323ml\;H_2/L$ was produced daily from Run II where 500 ml of heattreated sludge in methane fermenter was injected, and methane produced from methane fermenter did not show big difference regardless of the amount of returning sludge at each Run. It was concluded that the two-phase anaerobic process was the appropriat process to produce hydrogen and methane simultaneously and stably. Influent $TCOD_{Cr}$ to two-phase anaerobic process showed the range of 132~145 g/L(average 140 g/L), and effluent $TCOD_{Cr}$ range was 25~40 g/L(average 32 g/L), and organic removal efficiency showed 71~82%(average 76.3%).

• 대한기계학회논문집B
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• 제28권11호
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• pp.1398-1406
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• 2004

The nonlinear signals from an impedance meter for the area average void fraction in two-phase flow have been analyzed to construct a phase space trajectory. The pseudo phase space was constructed with the time delay and proper dimensions. The time delay and the embedding dimension were chosen by the average mutual information and by the false nearest neighborhood, respectively. The attractor-density-map of projected states was used to produce the two dimensional probability distribution functions (2D-PDF). Since the developed 2D-PDF showed clear distinction of the flow patterns, the flow regime identification was made with three rules and with the 2D-PDF. Also, the transition criteria of Mishima-Ishii agree well with the present results.

• Journal of Animal Science and Technology
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• 제66권3호
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• pp.493-503
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• 2024

The aim of this experiment was to evaluate the effects of low crude protein (CP) level with essential amino acids (AA) addition on growth performance, nutrient digestibility, microbiota, and volatile fatty acid composition in growing pigs. A total of 160 growing pigs (Landrace × Yorkshire × Duroc [LYD]; average initial body weight 16.68 ± 0.12 kg) were randomly allotted to one of the four treatments on the basis of initial body weight. A randomized complete block design was used to conduct this experiment in the Research Center of Animal Life Sciences at Kangwon National University. There were ten pigs/replicate with four replicates in each treatment. The treatments include; CON (Control, 17.2% dietary CP level), low protein (LP)-1.10 (15.7% dietary CP level + 1.10% lysine level), LP-1.15 (15.7% dietary CP level + 1.15% lysine level), LP1.2 (15.7% dietary CP level + 1.20% lysine level). The pigs fed CON and LP-1.2 diet showed greater final body weight than that of LP-1.1 diet (p < 0.05). Although average daily gain, average daily feed intake, and feed efficiency did not show any difference in phase 2 and 3, average daily gain and feed efficiency was significantly greater in CON and LP-1.20 in phase 1. However, the average daily feed intake did not show any difference during the experimental period. Isobutyric acid and isovaleric acid composition of LP treatments were lower than CON treatment in phase 2. Total branched chain fatty acid composition was significantly lower in LP treatment in phases 1 and 2. However, there was no significant difference among treatments in phase 3. The results of this study underscore the importance of AA supplementation when implementing a low-protein diet during the early growth phase (16-50 kg) in pigs.

• 전력전자학회논문지
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• 제3권3호
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• pp.191-198
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• 1998

본 논문에서는 브러시리스 직류 전동기의 상 전류 제어를 위해 유니폴라 PWM 방식이 적용될 때 상 전환에 의한 토크 맥동을 저감시키기 위한 새로운 전류 제어 방식을 제안한다. 상 전환은 통전된 상의 평균 전압의 순간적인 변동을 야기시켜 전류에 맥동을 발생시키고, 이 맥동 전류는 토크 맥동을 발생시킨다. 본 논문에서는 PWM 패턴에 따를 전환 구간에서의 통전된 상의 평균 전압 변화를 분석하고 평균 전압 변동을 보상하기 위한 전류 제어기를 설계한다. 그리고 실험 결과를 통하여 제안된 방식의 효용성을 입증한다.

• 농업과학연구
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• 제45권4호
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• pp.677-685
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• 2018

Weaning pigs often face post-weaning challenges such as diarrhea, low feed intake, and body weight (BW) loss which affects the health and economic value of weaning pigs. Interestingly, the use of yeast cultures (YCs) as feed supplements for pigs has increased markedly in recent years. This study evaluated the effects of yeast cultures (Saccharomyces cerevisiae) on the growth performance, fecal score, and nutrient digestibility of weaning pigs. A total of 50 crossed healthy weaning pigs [(Yorkshire ${\times}$ Landrace) ${\times}$ Duroc] with an average BW of $7.46{\pm}1.60kg$ (28 day of age) were used in a 6-week experiment. The experiment was divided into 3 phases (Phase 1, 1 - 2 weeks; Phase 2, 2 - 4 weeks; Phase 3, 4 - 6 weeks). Dietary treatments were as follows: 1) CON: basal diet and 2) CON + 0.50% YC. During phase 1, the average daily gain (ADG) and average daily feed intake (ADFI) were significantly increased (p < 0.05) in the weaning pigs fed YC supplementation diets compared with the weaning pigs fed the CON diet. During phase 3 as well as overall, the gain/feed ratio (G/F) was significantly increased (p < 0.05) in the YC supplementation group compared with the pigs fed the CON diet. In conclusion, the supplementation of YCs in the diet positively affected the growth performance of weaning pigs during the first two weeks after weaning.

• 한국운동역학회지
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• 제13권2호
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• pp.49-63
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• 2003

For this study, four male university Taekwondo players were randomly chosen, between the weight categories of 60Kg and 80Kg. Their side kicks (yeop chagi), which are part of foot techniques, were kinematically analyzed in terms of the time, angle, and angular velocity factors involved with the kicks through the three-dimensional imaging. The results of the analysis are as fellows. 1. Time factor The first phase(preparation) was 0.48sec on average, accounting for 60% of the entire time spent; the second phase(the minimum angle of the knee joint) was 0.21sec on average, taking up 26% of the whole time spent; and the third phase(hitting) was 0.11sec on average, representing 14% of the entire time spent. 2. Angle factor In the first phase(preparation), rotating their bodies along the long axis, the players bended their hip and knee joints a lot, by moving fast in the vertical and horizontal directions, in the second phase(the minimum angle of the knee joint), the players continued to extend their bodies along the vertical axis, while pronating their lower legs and bending their hip and knee joints a lot to reduce the radius of gyration, and in the third phase(hitting), they extended their knee joints greatly so that the angle movements of their lower bodies shifted to circle movements. 3. Angular velocity factor In the first phase(preparation), the angular velocity of the hip and knee joints increased. while moving horizontally and rotating the body along the long axis; in the second phase(the minimum angle of the knee joint), the angular velocity increased by bending the hip and knee joints fast to reduce the rotation radios; and in the third phase(hitting), the angular velocity was found to have increased, by rotating the body along the long axis to increase the angular velocity and shifting the angular momentum of the pronated knee joint to the circular momentum.

• 농업과학연구
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• 제50권3호
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• pp.355-362
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• 2023

A total of 96 weanling pigs with an initial body weight of 5.96 ± 0.08 kg were randomly allocated to two dietary treatments and fed experimental weaning diets for 36 days in three phases; phase 1: day 1 to 7; phase 2: day 8 to 21, and phase 3: day 22 to 36. Treatments consisted of a basal diet (CON) containing 334.0 g/kg dried whey versus a lactic acid (LA) supplemented diet containing 313.6 g/kg dried whey with 10 g/kg LA during phase 1; a CON diet containing 200.0 g/kg dried whey versus an LA diet containing 186.0 g/kg dried whey with 7 g/kg LA during phase 2. During phase 3, both CON and LA groups were fed a diet without dried whey and LA. Pigs fed the LA diet had a higher average daily feed intake ADFI (p = 0.014) and reduced (p = 0.035) gain-feed ratio compared to pigs fed CON diet in phase 2. In phase 3, the average daily gain and feed intake were both increased (p = 0.026 and; p = 0.010, respectively) in the pigs previously fed the LA diet than those fed the CON diet. The apparent total tract digestibility of dry matter and, nitrogen, and the digestible energy were decreased (p < 0.05) in the LA diet group on day 7; however, increased (p < 0.05) digestibility of dry matter and nitrogen and digestible energy was observed at the end of phase 2 and 3. In conclusion, the inclusion of LA was inferred to have improved the average daily gain, feed intake, and nutrient digestibility during the late weanling period of pigs.

• 한국대기환경학회지
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• 제30권1호
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• pp.59-67
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• 2014

In 1995 Kimchi refrigerator was developed at first, and has used HFC-134a as refrigerant. Kimchi refrigerator has been made 1,044,694 on the basis of 2010, disposed about 160,000 per year. Although mobile air conditioning, commercial refrigerator, general refrigerator is regarded as a major source of HFC-134a, little information is available for its emission characteristics of HFC-134a. This paper addresses the fugitive emission factors of Kimchi refrigerator at use-phase and disposal-phase. The residual quantities of Korean-made fifty three waste Kimchi refrigerators were weighed using a commercial recover of refrigerants to determine the emission factors at the disposal-phase. On the other hand, the emission factors at use-phase were estimated from the residual quantities and operating times. The average residual rate of forty three scarp Kimchi refrigerators is determined to be $74.6{\pm}5.2%$. The emission factor at the use-phase is estimated to be $3.5{\pm}0.8%/yr$ as a result of using average age of 11.7 years and the average residual rate determined here. The emission factor at the disposal-phase is determined to be 31.3% after adopting 58% of the recycling rate of refrigerant reported by Recycling Center. We estimate 3.1 g/yr for the average emission quantity of HFC-134a per operating refrigerator, while 22.5 g for that per waste Kimchi refrigerator. Since the chemical compositions of refrigerant of waste Kimchi refrigerator were the same as those of new refrigerant, it is expected that the HFC-134a recovered from waste Kimchi refrigerator can be reused for refrigerant.

• 한국운동역학회지
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• 제31권4호
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• pp.283-289
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• 2021

Objective: The aim of this study was to analyze the pattern of Kolman technique by five Korean top gymnasts including the three national athletes on horizontal bar. Method: Two digital high-speed camcorders were used with 90 frames/sec and their Kolman motions were filmed in sports science secondary school gymnasium at U city. After the kinematic and kinetic variables were carried out by Kwon3D 3.1 motion package during the whole phase, the optimized release motion was investigated by simulating the body COG path during the aerial phase. Results: Firstly, it was revealed that the average changes of hip, shoulder joint angle were 84 deg, 53 deg respectively during the functional sub-phase and the average swing phaseal time was 1.21 s. Secondly, it was revealed that the average body COG positions and velocities (Y, Z) at release were -0.65 m, 0.48 m, 1.65 m/s, 3.97 m/s respectively and the average release angle, peak height and flight time were 67 deg, 1.29 m, 0.79 s respectively. Thirdly, it was revealed that the directions of somersault of whole and lower body, tilt of lower body were counterclockwise, whereas the directions of tilt of whole body, twist of whole and lower body were clockwise at the ready for re-grasp. Lastly, it was revealed that the body COG paths were different from each other during the aerial phase followed by the different body COG velocities. Conclusion: Korean gymnasts of this study controlled their motions well in terms of the timing of hip·shoulder joint, body position, body angular momentum especially during the functional sub-phase, but their motions were different during the aerial phase. Nonetheless most of them made the adequate body position at the instant of re-grasp. It would be suggested that Korean gymnasts except S3 should increase the vertical velocity.