• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2005.10a
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• pp.269-274
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• 2005

This study gathered the factor of supply chain risk through literature review, and measured the importance of risk factors which have been recognized by domestic companies. This study has purposes and necessities as follows. First, supply risk factors were classified and explored through positive studies about supply chain risk. Most of previous studies helps grasping the meaning of supply chain risk but limited in conceptual side. Second, this study used AHP(Analytic Hierarchy Process) method which makes decision-making problem classified, simplicated and systematized to evaluate the importance of supply-chain risk recognized by the companies. Finally, this study suggests registration-point in companies's efficient supply activity would be great by measuring the importance of supply-chain through AHP(Analytic Hierarchy Process).

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.1
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• pp.436-440
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• 2014

To verity the effect of PCB plane layer to the output characteristics of the Switched Mode Power Supply (SMPS), this paper compared with a generic one-layer PCB and a double-side PCB. This paper specially focused on the voltage, the current and the high frequency noise of the output characteristic of the SMPS, using a double-side PCB which has same layout and was installed a ground plane on the opposite side. This double-side PCB was assembled by all same components which used on the SMPS using the single-side PCB. The experiment results show the SMPS using the ground plan PCB can efficiently reduce the high frequency noise to 50mV at 100MHz from 150mV in the single-side PCB. And the results also show the high harmonics frequency was reduced as well.

• Journal of Power Electronics
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• v.9 no.1
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• pp.109-116
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• 2009

This paper addresses the output control of a utility-connected double-fed induction machine (DFIM) for wind power generation systems (WPGS). DFIM has a back-to-back converter to control outputs of DFIM driven by the wind turbine for WPGS. To supply commercially the power of WPGS to the grid without any problems related to power quality, the real and reactive powers (PQ) at the stator side of DFIM are strictly controlled at the required level, which in this paper is realized with the Fuzzy PI controller based on the field orientation control. For the Sinusoidal Pulse Width Modulation (SPWM) converter connected to the rotor side of DFIG to maintain the controllability of PQ at the state side of DFIM, the DC voltage of the DC link capacitor is also controlled at a certain level with the conventional Proportion-Integral (PI) controller of the real power. In addition, the power quality at the grid connected to the rotor side of DFIM through the back-to-back converter is maintained in a certain level with a PI controller of the reactive power. The controllers for the PQ at the stator side of DFIM, the DC link voltage of the back-to-back inverter and the reactive power at the grid connected to the rotor side of DFIM are designed and simulated in the PSIM program, of which the result verifies the performance of the proposed controllers.

• Nuclear Engineering and Technology
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• v.56 no.8
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• pp.3315-3329
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• 2024

Small Modular Reactors (SMRs) adopt the Helically Coiled Once-Through Steam Generators (OTSG) extensively for its compactness and higher heat transfer efficiency. As a heat exchanger between the primary side (reactor coolant system) and the secondary side (feedwater and steam system) of nuclear steam supply system, the inlet/outlet conditions both of shell side and tube side of OTSGs have significant impacts on overall system response. Considering the flexible operation of SMRs and heat application by extracting steam, a simulation tool for accurate prediction of the OTSG dynamic behaviors would be required for optimizing design and control. In this study, the OTSG dynamic simulation model has been developed. Mathematical governing equation has been derived by using moving boundary approach and a simulation module has been developed by using Modelica Language. The developed module has been compared with publicly available experimental results and benchmarked with MARS-KS calculation results. Also, it has been incorporated into the integrated SMR model (i.e., reactor core, primary side, secondary side) and dynamic behaviors with reactivity feedback and heat balancing have been investigated. In both of steady-state and transient conditions, it shows the promising accuracy.

• The Transactions of the Korean Institute of Power Electronics
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• v.21 no.4
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• pp.302-311
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• 2016

This paper proposes a hybrid ESS that integrates an energy storage system (ESS) with an uninterruptible power supply (UPS). The hybrid ESS has a demand management and emergency power supply function while increasing the battery utilization of the UPS, which has just been used in a power failure. In addition to the critical load, the proposed system augments the capacity of emergency generation using an additional load, which has voltage and frequency-dependent characteristics to the grid side. The control algorithm of the AC-DC converter and bidirectional DC-DC converter is proposed for demand management and emergency power supply. Furthermore, seamless and autonomous transfer methods to alleviate the transient during mode transfer are proposed. To validate the proposed control scheme, experimental results from a 5 kW prototype are provided.

• Journal of Korean Society for Quality Management
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• v.37 no.3
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• pp.102-122
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• 2009

In this study, we will conduct an empirical study to see how the 3PL firm's logistics service quality and relationship orientation affects the supply chain performance. To examine the research model and hypotheses, we have used an empirical method based on the field survey in which most of measurements used and verified in previous studies are selected as measurements. The results of our empirical study can be summarized as follows: First, it can be shown that higher level of logistics service quality not only affects satisfaction and relationship orientation positively, but also improves supply chain performance. Second, it can be also shown that satisfaction for logistics service quality affects relationship orientation between shipper and 3PL firm positively. Finally, it can be shown that relationship orientation affects supply chain performance positively. This paper presents much implications both theoretical and practical side.

• Journal of Korea Port Economic Association
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• v.21 no.4
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• pp.55-74
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• 2005

This study focuses on affording a material basis for rearranging the manpower supply system in port and logistics industry for Busan's international competitiveness strategies. First of all, the current state and future plan of port and logistics industry, as Busan's main strategic industry, are reviewed. Then theoretical background are introduced for the estimate of demand. As a methodology of this research, Cubic model is applied to estimate the demand of manpower by using 10 year time series data from 1993 to 2002. This paper also surveyed the supply side of port and logistics industry manpower in Busan area. The amounts of mismatched equilibrium between the demand and the supply are measured in this study. The concluding remarks shows some suggestions for the problem of mismatch and the relating policy planning.

• Journal of Technology Innovation
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• v.4 no.1
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• pp.185-207
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• 1996

It is frequently pointed out that the Korean economy, with its scarce natural resources, would never have been able to achieve current levels of economic development without the massive provision of well-educated, hardworking human resources. Throughout the industrialization process ,full-fledged deployment and mobilization of qualified human resources have been the foundation to industrial policy and S&T policy. This paper describes the development of S&T human resources in Korea using various statistics including educational enrollment rates, unemployment rates, the allocation of researchers and R&D expenditures among sectors of performance, educational composition of employment within and across industries, technical human resource shortage rates, relative wage levels of SMEs, and composition of labor force by age-group and gender. While analyzing S&T human resources development, this paper discusses issues such as the mismatched demand and supply of skill and knowledge levels of the highly educated, the unbalanced distribution of S&T human resources between sectors, and the low utilization of the female and aged labor force. This paper suggests that the policy maker applies a hybrid of quantitative and qualitative policies to reduce the mismatches of supply and demand of skill and knowledge levels for each labor market categorized according to supply side.

• Proceedings of the KIEE Conference
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• 2001.07a
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• pp.330-332
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• 2001

This paper reviews technology for power quality differentiated supply in power system. Since price and power quality has been single goods in the light of customer-side view point but hereafter it is essential for power market to introduce multiple goods which is composed of differentiated combination between them. This paper should like to work out strategy for power quality differentiated supply in domestic power system by comparison characteristics of differentiated background and its relevant various theory.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.67 no.12
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• pp.1602-1610
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• 2018

Induction heating can convert electrical energy to thermal energy with high conversion efficiency and quick heating. Currently, a current source rectifier/inverter-fed parallel resonant circuit is widely used as an induction heating power supply for forging applications. However, the conventional induction heating power supplies composed of phase-controlled rectifier and SCR inverter have low efficiency and low power factor at input side, and require additional starting circuitry. So this paper proposes new induction heating power supply topologies for forging applications which have high power factor, high efficiency, and large output power. It also suggests detailed design guideline.