• Proceedings of the KSME Conference
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• 2001.06d
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• pp.343-347
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• 2001

Advanced Pressurized Reactor 1400(APR-1400), which is a standard evolutionary advanced light water reactor(ALWR), has been developed from 1992 as one of long-term Government Project(G-7). The APR-1400 is designed to operate at the rated output of 4000MWt to produce an electric power output of around 1450MWe. The balance of plant (BOP) for the secondary system consists of main steam, feedwater, condensate, turbine generator and auxiliary system. In this paper, we describe the major design features of secondary component, balance of plant configuration, and then the turbine cycle thermal performance evaluation using PEPSE code.

• Journal of Power System Engineering
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• v.17 no.6
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• pp.54-62
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• 2013

A numerical analysis is performed to evaluate mass flow balance in the heat exchanger for the dehumidifier. To improve the mass flow balance for maximum heat transfer performance, inlet, outlet and baffle are changed. Mass flow balance is evaluated by non-uniformity of flow which is the same concept with the standard deviation. Usually, there will occur many paths between the inlet and the outlet, however, it will follow shortest and low resistance ways. The uniform distribution of flow is numerically analyzed for several types of heat exchangers. Making the shortest way between the inlet and the outlet is most important factor. Two types of heat exchangers are installed in the dehumidifier and 4 cases of Type A heat exchangers and 3 cases of Type B heat exchangers are evaluated and optimized. The result of this research is applied to design heat exchanger for commercial dehumidifiers.

• Transactions of The Korea Fluid Power Systems Society
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• v.5 no.1
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• pp.13-19
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• 2008

The typical hydraulic system of hoist is composed of a hydraulic supply unit, a directional control valve, counter balance valve, and flow control valves. The flow capacity coefficients of flow control valves should be adjusted so that the hoist is operated at moderate speed and the hydraulic energy loss is minimized. However, it is difficult to adjust the flow coefficients of flow control valves by trial and error for optimal operation. Here, the steady state model of the hoist hydraulic system including the differential cylinder circuit is derived and the optimal flow capacity coefficients of flow control valves are obtained using the complex method that is one kind of constrained direct search method.

• Journal of Digital Convergence
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• v.17 no.6
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• pp.389-399
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• 2019

The purpose of this study was to investigate the effects of muscle asymmetry of knee joint among elite cyclists on anaerobic pedaling power related capacity. In another word, based on isokinetic strength of Non-Dominant, ND and Dominant, D, side, high, moderate and low ratio of ND to D were classified as High Symmetry Group, Moderate Symmetry Group and Asymmetry Group, respectively. Analysis of muscle asymmetry of extensor's ND and D side might not lead to any difference between the three groups. Based on muscle strength analysis of the flexor's ND and D, there was statistical difference between the groups in ND flexor and in the muscle balance index of the flexor muscle. This result also leads to significant difference in pedaling power functionality, but this effects might not lead to any negative pedaling power. Therefore, among even cyclists who may show almost the same recruitment pattern of ND and D side during pedaling stroke muscle asymmetry could exist but this phenomena might not negatively contribute to the pedaling capacity.

• Korean Journal of Occupational Health Nursing
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• v.26 no.4
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• pp.261-272
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• 2017

Purpose: The study aimed to identify factors influencing work-life balance in female service workers. Methods: A cross-sectional descriptive study was conducted with an online survey of 234 service workers using volunteer panels. Data were collected using a self-administered questionnaire from July 16 to 24, 2017. Major variables included work-life balance, resilience, emotional intelligence, job stress, and fatigue. Using the SPSS 24.0 program, descriptive statistics, t-test, ANOVA, correlation analysis, and multiple regression analysis were conducted. Results: The mean score of the work-life balance level of female service workers was $2.9{\pm}0.85$ on a total score of 6. A multiple regression analysis revealed that smoking, resilience, job stress and fatigue were statistically significant factors in the model (p<.001), with an explanatory power of 50.3%. Emotional intelligence was not significantly associated with work-life balance. Conclusion: The level of work-life balance was considerably low in female service workers. This study suggests that nursing interventions to enhance work-life balance are required at both the individual and organizational levels.

• KIPE Magazine
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• v.7 no.2
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• pp.40-43
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• 2002

• Journal of Power Electronics
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• v.10 no.4
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• pp.351-356
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• 2010

A new current-balancing multi-channel LED driver is proposed in this paper. The conventional LED driver system consists of three cascaded power conversion stages and its driver stage has the same number of expensive boost converters as those of the LED channels. On the other hand, the proposed LED driver system consists of two cascaded power stages and its driver stage requires only passive devices instead of expensive boost converters. Nevertheless, all of the currents through multi-channel LEDs can be well balanced. Therefore, it features a smaller system size, improved efficiency, and lower cost. To confirm the validity of the proposed driver, its operation and performance are verified on a prototype for a 46" LCD TV.

• Journal of Power Electronics
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• v.19 no.1
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• pp.58-67
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• 2019

This study presents a new portable eight-output light emitting diode (LED) driver. The eight output-channels are divided into two equal groups, and their output powers can be controlled individually by three active switches. In addition, a simple capacitor-based passive current balancing circuit (CBC) is employed in each port to guarantee that the currents of the four LEDs are the same. When compared with the conventionally used separate two-output isolated converters, the proposed one uses one less active switch. Moreover, zero-voltage-switching (ZVS) is achieved, which improves the power efficiency of the driver. Finally, a highly compact prototype is built, which can reach an efficiency of 94.6%.

• Journal of Drive and Control
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• v.9 no.2
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• pp.8-14
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• 2012

Electro-hydraulic spring return actuator(ESRA) is utilized for air conditioning facilities in a nuclear power plant. It features self-contained, hydraulic power that is integrally coupled to a single acting hydraulic cylinder and provides efficient and precise linear control of valves as well as return of the actuator to the de-energized position upon loss of power. In this paper, the algebraic equations of ESRA at steady-state have been developed for the analysis of static characteristics that includes control pressure and valve displacement of pressure reducing valve, flow force on flapper as well as its displacement over the entire operating range. Also, the effect of external load on piston deviation is investigated in terms of linear system analysis. The results of static characteristics show the unique feature of force balance mechanism and can be applied to the stable self-controlled mechanical system design of ESAR.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.48 no.7
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• pp.363-368
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• 1999

The parallel operation system of multiple uninterruptible power supplies(UPSs) is used to increase power capacity of the system or to secure higher reliability at critical loads. In the parallel operation of the two UPSs, the load-sharing control to maintain the current balance between them is a key technique. Because a UPS has low output impedance and quick response characteristics, in case of an unbalanced load inverter output current changes very rapidly and thereby can instantaneously reach an overload condition. In this study, high precise load-sharing controller is proposed and implemented for the parallel operation system of two UPSs with low impedance characteristics and this controller controls the frequency and the voltage to minimize the active power component and the reactive power component which are gotten from the current difference between two UPSs. And then a good performance of the proposed method is verified by experiments in the parallel operation system with two 40KVA UPSs.