• Proceedings of the KIPE Conference
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• 2001.07a
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• pp.46-49
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• 2001

An investigation into power conditioners that interface with photovoltaic array and utilities has been completed. The rating for this investigation is residential system(3-5kVA) that interface with a 220V single phase utility connection. As the result of this investigation, a 3kVA high frequency PWM IGBT inverter feeding a high frequency isolation transformer with a sinusoidal current wave was selected. The output of the transformer rectified with a diode bridge rectifier. four IGBT, used as 60Hz switched, reverse the polarity of the rectified current on every other half cycle of the utility voltage. Even though the high frequency link system used more power semiconductors, a net size, weight, and parts cost saving result compared to the other systems due to elimination of 60Hz transformer.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2006.05a
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• pp.395-398
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• 2006

this paper provides a novel method to start the linear engine coupled linear generator from dead stop to its final steady state operation. This method depends mainly to use the linear generator mounted on the shaft of the linear engine to provide the required thrust force to move and oscillate the linear engine from bottom to top dead centers. It is a cost effective approach to start the internal linear combustion engine using its coupled tubular permanent magnet linear generator proposed here. This linear generator operates in this case in motoring mode, providing the required thrust force by feeding this linear generator phases with currents by using a three phase PWM inverter controlled by position feedback scheme. In order to provide the desired thrust force with specific value and direction, a position feedback is required to control the free piston engine motion through controlling the inverter switches using PWM control scheme.

• Journal of Power Electronics
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• v.10 no.6
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• pp.724-732
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• 2010

This paper presents an effective rotor current controller for variable-speed stand-alone doubly fed induction generator (DFIG) systems feeding an unbalanced three-phase load. The proposed current controller is developed based on proportional plus two resonant regulators, which are tuned at the positive and negative slip frequencies and implemented in the rotor reference frame without decomposing the positive and negative sequence components of the measured rotor current. In addition, the behavior of the proposed controller is examined in terms of control performance and stability with respect to rotor speed variations, i.e., slip frequency variations. Simulations and experimental results are shown to validate the robustness and effectiveness of the proposed control method.

• Journal of Power Electronics
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• v.19 no.5
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• pp.1153-1161
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• 2019

A current sharing controller is proposed in this paper for parallel-connected converters. The proposed controller is based on the calculation of the magnitudes of system current space vectors. Good current distribution between parallel converters is achieved with only one Proportional-Integral (PI) compensator. The proposed controller is analyzed and the circulating current impedance is derived for paralleled systems. The performance of the new control strategy is experimentally verified using two parallel connected converters employing Space Vector Pulse Width Modulation (SVPWM) feeding a passive RL load and a 2.2 kW three-phase induction motor load. The obtained test results show a reduction in the current imbalance ratio between the converters in the experimental setup from 53.9% to only 0.2% with the induction motor load.

• Journal of Species Research
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• v.12 no.1
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• pp.109-113
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• 2023

To build a distribution model for Haemadipsa rjukjuana, we collected current occurrences of the species on Heuksando with adjacent islands. Based on current locations and 19 climate variables with DEM (digital elevation model), we built the MaxEnt (maximum entropy) species distribution model for H. rjukjuana in the islands. Then, we applied the MaxEnt model to the mainland of Korea with the current climate condition and topology. In addition to the current distribution scenario, we predicted the future distribution scenarios in Korea by Coupled Model Intercomparison Project Phase 6 (CMIP6) global climate models. Shared Socioeconomic Pathway (SSP) 585 of two CMIP6 models(GISS-E2-1 and INM-CM4-8) from 2040 to 2100 were used for the future projection.

• Asian-Australasian Journal of Animal Sciences
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• v.29 no.7
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• pp.979-986
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• 2016

This experiment was conducted to investigate the effects of dried mealworm (Tenebrio molitor larva) on growth performance, nutrient digestibility and blood profiles in weaning pigs. A total of 120 weaning pigs ($28{\pm}3days$ and $8.04{\pm}0.08kg$ of body weight) were allotted to one of five treatments, based on sex and body weight, in 6 replicates with 4 pigs per pen by a randomized complete block design. Supplementation level of dried mealworm was 0%, 1.5%, 3.0%, 4.5%, or 6.0% in experimental diet as treatment. Two phase feeding programs (phase I from 0 day to 14 day, phase II from 14 day to 35 day) were used in this experiment. All animals were allowed to access diet and water ad libitum. During phase I, increasing level of dried mealworm in diet linearly improved the body weight (p<0.01), average daily gain (ADG) (p<0.01) and average daily feed intake (ADFI) (p<0.01). During phase II, ADG also tended to increase linearly when pigs were fed higher level of dried mealworm (p = 0.08). In addition, increasing level of dried mealworm improved the ADG (p<0.01), ADFI (p<0.05) and tended to increase gain to feed ratio (p = 0.07) during the whole experimental period. As dried mealworm level was increased, nitrogen retention and digestibility of dry matter as well as crude protein were linearly increased (p = 0.05). In the results of blood profiles, decrease of blood urea nitrogen (linear, p = 0.05) and increase of insulin-like growth factor (linear, p = 0.03) were observed as dried mealworm was increased in diet during phase II. However, there were no significant differences in immunoglobulin A (IgA) and IgG concentration by addition of dried mealworm in the growth trial. Consequently, supplementation of dried mealworm up to 6% in weaning pigs' diet improves growth performance and nutrient digestibility without any detrimental effect on immune responses.

• Journal of Animal Science and Technology
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• v.61 no.1
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• pp.1-9
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• 2019

Little is known about the effects of the plane of nutrition on growth performance and meat quality of grow-finish pigs under commercial production conditions. The present study was thus addressed to this virtually unanswered question. One hundred and two barrows and 102 gilts weighing approximately 24 kg were fed phase I and II grower diets with a high, medium, or low plane of nutrition (HP, MP, or LP) to approximately 43 and 70 kg, respectively, in 6 replicates (pens). Subsequently, the HP and MP groups were fed the HP and MP1 finisher diets, respectively, the LP group being fed a second MP (MP2) finisher diet (LP1 group). Moreover, 68 LP-grower-fed barrows and gilts were added to the feeding trial and fed the MP1 and LP finisher diets to approximately 95 kg and thereafter, respectively (LP2 group). All MP diets had the lysine:calorie ratios comparable to the RNC recommendations, with < 18% differences between those of the HP and LP diets. The finisher pigs were reared in 16 pens and slaughtered at approximately 115 kg. The gain:feed ratio, but not average daily gain (ADG), was greater for the HP group than for the MP and LP during the grower phase I whereas during the grower phase II, ADG was greater (p < 0.05) for the HP and LP groups vs. MP. During the finisher phase I, ADG was less for the LP (LP1 + LP2) group vs. HP and MP, with no difference between the HP and MP groups; the gain:feed ratio was less for the LP vs. MP group. Backfat thickness was greater for the LP vs. HP group. The water holding capacity of fresh longissimus dorsi muscle (LM) and the sensory juiciness score for cooked LM were greatest for the LP group, the sensory flavor and tenderness scores being greater for the LP group vs. MP. In conclusion, results suggest that compensatory growth occurred for the LP and MP groups during the grower phase II and finisher phase I, respectively, with fat deposition increased for the LP group and that meat quality could be improved by the use of LP.

• Journal of the Korean Society for Railway
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• v.17 no.3
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• pp.171-177
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• 2014

PWM converter trains exhibit excellent load characteristics in comparison with conventional phase-controlled trains with low power factors, as they can be operated at power factors which are close to unity by means of a voltage vector control method. However, in the case of a high track density or extended feeding, significant line losses and voltage drops can occur. Instead of operating these trains at a fixed unity power factor, this paper suggests a continuous optimal power factor control scheme for each train in an effort to minimize line losses and improve voltage drops according to varying load conditions. The proposed method utilizes the steepest descent algorithm targeting each car in the same feeding section to establish the optimized reactive power compensation levels that can minimize the reactive power loss of the feeder. The results from a simulation of a sample system show that voltage drops can be improved and line losses decreased.

• Asian-Australasian Journal of Animal Sciences
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• v.22 no.10
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• pp.1407-1413
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• 2009

An experiment was conducted to investigate the effects of dietary supplementation of feather meal (FM) on the performance of pigs and taurine content in pork. A total of 135 cross-bred (L${\times}$Y${\times}$D) pigs, weighing an average 46 kg, were assigned to five dietary treatments; Control, 3% FM supplemented diet (3% FM), 3% FM and 10 ppm pyridoxin supplemented diet (3% FMpyridoxin), 6% FM supplemented diet (6% FM) and 6% FM and 10 ppm pyridoxine supplemented diet (6% FM-pyridoxin). Each treatment had 3 replications of 9 pigs (4 gilts and 5 barrows) each. Pigs were fed for 11 weeks under a phase feeding program which consisted of grower (0-3 week), grow-finisher (4-8 week) and finisher (9-11 week) periods. During the whole feeding period, ADG and ADFI of pigs fed FM treatments tended to increase in general compared to the control. Feed conversion ratio (feed/gain) of the control was significantly (p<0.05) lower than FM treatments. Taurine content of the control was highest in heart muscle (1,393.8 ppm) followed by liver (647.3 ppm), tenderloin (601.2 ppm), ham (462.4 ppm) and loin (375.8 ppm). Taurine contents of heart, tenderloin, ham and loin were significantly (p<0.05) increased by FM treatments. Taurine content was highest in the 6% FM-pyridoxin treatment. Taurine content of heart, tenderloin, ham and loin on 6% FM-pyridoxin supplementation were increased by 91%, 23%, 27% and 29%, respectively, compared with the control. Sensory tests of the pork showed that there was no consistent response among the treatments. In conclusion, supplementation of FM and pyridoxin to a pig diet can increase taurine content of the pork.

• Journal of the Korea Organic Resources Recycling Association
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• v.5 no.1
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• pp.25-32
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• 1997

The effect of levulinic acid (LA) and biosynthetic precursors of ${\delta}$-aminolevulinic acid (ALA) on the production of extracellular ALA was examined for the cells of soil derived Rhodospirillum rubrum N-1 belonged to the genus Rhodospirillaceae. The extracellular yield of ALA was increased to 23 fold (45 mg/l) from the basal condition (Lascelles' medium without L-glutamate) by successive addition of LA at initial (10 mM) and mid-log stage (30 mM) of cell cultivation. In addition to initial/mid-log mutual supplementations of LA (10 mM/30 mM) and glutamate (30/30 mM), respectively, by means of alternative feeding 10 mM $C_4$-precursors at mid-log phase of culture the extracellular ALA content was reached to 75 mg/l (40 fold).