• 동아시아식생활학회지
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• 제20권5호
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• pp.823-835
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• 2010

The research aimed to measure the efficiency of using multi stores in a foodservice company using by DEA (data envelopment analysis) which is a new management science technique. The study also attempted to identify relevant variables affecting DEA efficiency in order to suggest methods for improving efficiency. The data were collected from 148 contract foodservice operations, which were operated in similar fashion in October 2009. The DEA efficiency was calculated as an output-oriented BCC Model. Sales, and CSI (customer satisfaction index) were used as output variables whereas food cost, labor cost, and management expense were used as input variables to calculate the DEA efficiency. Operation process variables of the unit consisted of the were consist of ratio of regular employee, ratio of housekeeper, meal counts, meal price, food cost per meal, contract period, number of menu items, forecasting accuracy, order accuracy, inventory turnover, use of processed food, deviation of food cost, number of new menus, and number of events. According to the BCC score and profitability, units were classified into four groups: High efficiency-high profitability (HEHP), High efficiency-low profitability (HELP), Low efficiency-high profitability (LEHP), and Low efficiency-low profitability (LELP). The HEHP group contained 54 units, which mostly contracted management fee type and had a high meal price. The units were also very large and, served three meals. Twenty of the units were operated with high labor cost: most of these were factories and hospitals. The LEHP group contained 20 units, that were mainly office stores of large scale and medium price. Fifty-four LELP group had a low meal price. A high performance group must have high efficiency, profitability, and satisfaction. The BCC score was over 0.969, the meal price was over 4,116 won, the food cost was over 2,077 won, and meal counts per month were over 10,212 meals.

• 신재생에너지
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• 제1권1호
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• pp.37-43
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• 2005

High-efficiency silicon solar cells have potential applications on mobile electronics and electrical vehicles. The fabrication processes of the high efficiency cells necessitate com placated fabrication precesses and expensive materials. Ti/Pd/Ag metal contact has been used only for limited area In spite of good stability and low contact resistance because of Its expensive material cost and precesses. Screen printed contact formed by Ag paste causes a low fill factor and a high shading loss of commercial solar cells because of high contact resistance and a low aspect ratio. Low cost Ni/Cu metal contact has been formed by using a low cost electroless and electroplating. Nickel silicide formation at the interface enhances stability and reduces the contact resistance resulting In an energy conversion efficiency of $20.2\%\;on\;0.50{\Omega}cm$ FZ wafer. Tapered contact structure has been applied to large area solar cells with $6.7\times6.7cm^2$ in order to reduce power losses by the front contact The tapered front metal contact Is easily formed by the electroplating technique producing $45cm^2$ solar cells with an efficiency of $21.4\%$ on $21.4\%\;on\;2{\Omega}cm$ FZ wafer.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2005년도 전력전자학술대회 논문집
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• pp.439-441
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• 2005

A new LLC resonant converter with multiple outputs is proposed for high efficiency and low cost plasma display panel (PDP) power module. In the proposed converter, ZVS turn-on of the primary MOSFETs and ZCS nun-off of the secondary diodes are guaranteed in the overall input voltage and output load range. Moreover, the primary MOSFETs and the secondary diodes have low voltage stresses clamped to input and the output voltage, respectively. Therefore, the proposed converter shows the high efficiency due to the minimized switching and conduction losses. In addition, by employing the transformer, which has the two and more secondary side, the proposed converter can have multiple outputs and they show the great cross-regulation characteristics. As a result, the proposed converter can be implemented with low cost and compact size. The 500W prototype is implemented, which integrates the sustaining and addressing power supplies of PDP power module. The maximum efficiency is 96.8% and the respective output voltages are well regulated. Therefore, the proposed converter is suitable for high efficiency and low cost PDP power module.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제50권10호
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• pp.501-507
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• 2001

In this paper, new high-efficiency zero voltage switching (ZVS) AC-DC boost converter is proposed to achieve power factor correction by simplifing energy recovery circuit. A lot of high power factor correction circuits have been proposed and applied to increase input power factor and efficiency. Most of these circuits may obtain unity power factor and achieve sinusoidal current waveform with zero voltage or/and zero current switching. However, it is difficult for them to obtain low cost, small size, low weight, and low noise. The topology proposed to improve these problems can compact the devices in circuit and can achieve high efficiency ZVS AC-DC boost converter. Simulation and experimental results show that this topology is capable of obtaining high power factor and increasing the efficiency of the system.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2007년도 하계학술대회 논문집
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• pp.226-228
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• 2007

SRM drive systems are designed to meet operating standards such as low cost, constant torque independent of rotor position, a desired operating speed range, high efficiency, and high performance. In applications using small motors, low cost and high performance with self-starting capabilities are highly desired. This paper discusses a novel two phase SRM (TPSRM) that has high performance characteristics with self-starting capability, low manufacturing cost with a two phase inverter and simple magnetic structure, and high efficiency. The principle of operation, analysis, and simulation for design are presented. The machine design is verified using finite element analysis (FEA) software. Analysis and simulation results are given to validate the TPSRM design.

• 한국태양에너지학회:학술대회논문집
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• 한국태양에너지학회 2009년도 춘계학술발표대회 논문집
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• pp.235-240
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• 2009

Crystlline silicon solar cells markets are increasing at rapid pace. now, crystlline silicon solar cells markets screen-printing solar cell is occupying. screen-printing solar cells manufacturing process are very quick, there is a strong point which is a low cost. but silicon and metal contact, uses Ag & Al pates. because of, high contact resistance, high series resistance and sintering inside process the electric conductivity decreases with 1/3. and In pastes ingredients uses Ag where $80{\sim}90%$ is metal of high cost. because of low cost solar cells descriptions is difficult. therefore BCSC(Buried Contact Solar Cell) is developed. and uses light-induced plating, ln-line galvanization developed equipments. Ni/Cu matel contact solar cells researches. in Germany Fraunhofer ISE. In order to manufacture high-efficiency solar cells, metal selections are important. metal materials get in metal resistance does small, to be electric conductivity does highly. efficiency must raise an increase with rise of the curve factor where the contact resistance of the silicon substrate and is caused by few with decrement of series resistance. Ni metal materials the price is cheap, Ti comes similar resistance. Cu and Ag has the electric conductivity which is similar. and Cu price is cheap. In this paper, Ni/Cu/Ag metal contact cell with screen printing manufactured, silicon metal contact comparison and analysis.

• 전기학회논문지
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• 제58권11호
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• pp.2162-2167
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• 2009

A Low cost and variable speed brushless motor drive system with single switch per phase is presented. The motor drive is realized with a novel two-phase flux-reversal-free switched reluctance motor and a split AC two switch converter. The strategy of the controller and the converter for its realization are described. Comparisons between a split AC converter, asymmetric converter, split DC converter, single controllable switch converter, and N+1 converter are performed for its device rating, cost, switching losses and conduction losses, and converter efficiency. The split AC converter is analyzed and simulated to verify the characteristics of the converter circuitry and control feasibility and the simulation results are presented. The efficiency with various loads is numerically estimated and experimentally compared from viewpoint of subsystem and system in details. The focus of this paper is to compare the presented motor drive system to the asymmetric converter system throughout experiments and demonstrate single switch per phase converter having comparable efficiency as the asymmetric converter system.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2006년도 전력전자학술대회 논문집
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• pp.71-74
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• 2006

A new multi-output LLC resonant converter is proposed for high efficiency and low cost plasma display panel (PDP) power module. In the proposed converter, zero-voltage (ZV) turn-on of the primary MOSFETs and zero-voltage (ZC) turn-on and turn-off of the secondary diodes are guaranteed in the overall input voltage and output load ranges. In addition, the primary MOSFETs and the secondary diodes have the low voltage stresses clamped to input and the output voltages, respectively. Therefore, the proposed converter shows the high efficiency due to the minimized switching and conduction losses. Moreover, by employing the transformer with multiple secondary windings, the proposed converter can have multiple outputs, which show the great crossregulation characteristics. Therefore, the proposed converter is suitable for high efficiency and low cost PDP power module.

• Journal of Animal Science and Technology
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• 제64권2호
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• pp.312-329
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• 2022

Feed cost is the main factor affecting the economic benefits of pig industry. Improving the feed efficiency (FE) can reduce the feed cost and improve the economic benefits of pig breeding enterprises. Liver is a complex metabolic organ which affects the distribution of nutrients and regulates the efficiency of energy conversion from nutrients to muscle or fat, thereby affecting feed efficiency. MicroRNAs (miRNAs) are small non-coding RNAs that can regulate feed efficiency through the modulation of gene expression at the post-transcriptional level. In this study, we analyzed miRNA profiling of liver tissues in High-FE and Low-FE pigs for the purpose of identifying key miRNAs related to feed efficiency. A total 212~221 annotated porcine miRNAs and 136~281 novel miRNAs were identified in the pig liver. Among them, 188 annotated miRNAs were co-expressed in High-FE and Low-FE pigs. The 14 miRNAs were significantly differentially expressed (DE) in the livers of high-FE pigs and low-FE pigs, of which 5 were downregulated and 9 were upregulated. Kyoto Encyclopedia of Genes and Genomes analysis of liver DE miRNAs in high-FE pigs and low-FE pigs indicated that the target genes of DE miRNAs were significantly enriched in insulin signaling pathway, Gonadotropin-releasing hormone signaling pathway, and mammalian target of rapamycin signaling pathway. To verify the reliability of sequencing results, 5 DE miRNAs were randomly selected for quantitative reverse transcription-polymerase chain reaction (qRT-PCR). The qRT-PCR results of miRNAs were confirmed to be consistent with sequencing data. DE miRNA data indicated that liver-specific miRNAs synergistically acted with mRNAs to improve feed efficiency. The liver miRNAs expression analysis revealed the metabolic pathways by which the liver miRNAs regulate pig feed efficiency.

• Journal of Electrical Engineering and Technology
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• 제10권3호
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• pp.1015-1024
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• 2015

This paper introduces a low cost, high efficiency, high performance three-phase unified power quality conditioner (UPQC) by using four-switch three-phase inverters (FSTPIs) and an extra capacitor in the shunt active power filter (APF) side of the UPQC. In the proposed UPQC, both shunt and series APFs are developed by using FSTPIs so that the number of switching devices is reduced from twelve to eight devices. In addition, by inserting an additional capacitor in series with the shunt APF, the DC-link voltage in the proposed UPQC can also be greatly reduced. As a result, the system cost and power loss of the proposed UPQC is significantly minimized thanks to the use of a smaller number of power switches with a lower rating voltage without degrading the compensation performance of the UPQC. Design of passive components for the proposed UPQC to achieve a good performance is presented in detail. In addition, comparisons on power loss, overall system efficiency, compensation performance between the proposed UPQC and the traditional one are also determined in this paper. Simulation and experimental studies are performed to verify the validity of the proposed topology.