• Journal of the Economic Geographical Society of Korea
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• v.17 no.1
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• pp.86-97
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• 2014

Incheon Free Economic Zone is the first free economic zone specified in 2003 in Korea. Previous research on the Free Economic Zone has focused on the activation of the free economic zone or foreign investment issue at the level of the national economic plan. Related to the development of a free economic zone, studies are currently insufficient on the relevance of the local economy, the development of linkages with hinterland, and the balanced regional development. Therefore, this study tried to investigate the impact of Incheon Free Economic Zone to the local economy through analyzing the causes and characteristics of the imbalance between the regions in Incheon by comparing before (1996~2002) and after (2003~2009) of the Incheon Free Economic Zone legislation (2003). The result shows that development of the free economic zone has not been connected to the local economy activation and the ripple effect on the old town in Incheon. Further, the construction of a large apartment and infrastructure in the free economic zones have increased the disparity between the free zones and the old town.

• Proceedings of the KIEE Conference
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• 2003.07d
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• pp.2193-2196
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• 2003

기존의 멀티레이트 입력 (MRIC) 제어기는 제어 입력신호에 채터링 현상이 발생하여 추종응답에 리플이 발생하는 문제점이 있다. 이러한 리플현상을 해결하기 위해 피드포워드 보상기를 이용하여 이런 리플현상을 제거하는 방법이 제시되기도 하였다. 본 논문에서는 상태 공간에서 현재 추종기를 기반으로 리프팅 기법을 이용한 멀티레이트 입력제어기 설계를 소개한다. 본 제어기를 사용함으로써 제어입력 신호가 채터링이 생기지않음을 이산전달함수 관점에서 최종치 정리를 이용하여 증명한다.

• Proceedings of the KIEE Conference
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• 1996.11a
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• pp.370-372
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• 1996

A control scheme for the Voltage-sourced PWM converter based on space vector equations is introduced. The main advantages of this new control scheme are that sinusoidal line currents with nearly unity power factor, ripple-free DC voltage output are achevied without current sensors. The dynamical equations with battery model is derived. The proposed scheme is verified by computer simulation.

• Proceedings of the KIPE Conference
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• 2012.07a
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• pp.389-390
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• 2012

본 논문은 입력전류 리플이 없는 브릿지리스 세픽 컨버터를 제안한다. 제안된 컨버터는 브릿지 다이오드를 제거하여 도통손실을 줄이고 결합 인덕터와 보조 캐패시터를 사용하여 입력 전류 리플을 제거하였다. 제안된 회로의 동작원리를 설명하고, 시뮬레이션으로 확인한 후 130[W]급 하드웨어 프로토 타입을 이용하여 검증하였다.

• Proceedings of the KIPE Conference
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• 2015.11a
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• pp.42-43
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• 2015

본 논문은 출력 전류 리플이 없는 소프트 스위칭 승압 컨버터를 제안한다. 제안하는 컨버터는 결합 인덕터와 보조 커패시터와 보조 인덕터를 사용하여 스위치의 영전압 스위칭이 가능하도록 하여 스위칭 손실을 줄이고 출력 전류 리플을 제거하였다. 제안하는 회로의 동작원리를 설명하고, 시뮬레이션으로 확인한 후 60[W]급 하드웨어 시작품을 이용하여 검증하였다.

• Proceedings of the KIEE Conference
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• 1993.07b
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• pp.821-824
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• 1993

This paper deals with a $3{\phi}$ rectifier unit for telecommunication system. The rectifier unit is developed to Cope with the step-up of the AC input voltatage from 220V to 380V. By using a buck-type converter in the front-end, it keeps the input power factor high and reduces the voltage ripple in the dc output. It also has a very wide voltage regulation range, which lets the unit be applied for both the 220V and 380V input system. The study includes the power conversion scheme, control strategy, snubber circuit and finally, experimental results.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.10
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• pp.1782-1789
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• 2008

This paper presents the design of acoustic resonance(AR) free and dimmable electronic ballast for 1kW Metal-Halide Lamp(MHL). The proposed Ballast consists of a Full-Bridge(FB) rectifier, a passive power factor correction(PFC) circuit, a full-bridge inverter, an ignitor using LC resonance and a control circuit for frequency modulation and dimming control. Whereas a passive PFC provides advantages in terms of high reliability and low cost for constructing the circuit, it is difficult to supply a stable voltage because of the output voltage ripple that occurs with a period of 120Hz. Although the ballast can be designed with a small size and a light weight if it is driven at a switching frequency between 1 and 100 kHz, AR will occur if the eigenvalue frequency of the lamp coincides with the inverter's operation frequency. The operation frequency was modulated in real time according to the output voltage ripple to compensate for the variation in power supplied to the lamp and eliminate AR. For dimming, the method, which modulated drive frequency of FB inverter using the control of DC level by microprocessor, was used. The Dimming ranged at least from 600W to 1kw as rated power of the lamp with 4 stages. Performance of the proposed technique was validated through numerical analysis, computer simulation using Pspice and by applying it to an electronic ballast for a prototype 1kW MHL.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.38 no.5
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• pp.373-380
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• 2014

Film flows applied to shell-and-tube heat exchangers in various industrial fields have been studied for a long time. One boundary of the film flow interfaces with a fixed wall, and the other boundary interfaces with a gaseous region. Thus, the flows become so unstable that wavy behaviors are generated on free surfaces as the film Reynolds number increases. First, high-amplitude solitary waves are detected in a low Reynolds number laminar region; then, the waves transit to a low-amplitude, high frequency ripple in a turbulent region. Film thickness is the most significant factor governing heat transfer. Since the wave accompanied in the film flow results in temporal and spatial variations in film thickness, it can be of importance for numerically predicting the film's wavy behavior. In this study, various turbulent models are applied for predicting low-amplitude ripple flows in turbulent regions. The results are compared with existing experimental results, and finally, the applied turbulent models are appraised in from the viewpoint of wavy behaviors.

• Proceedings of the KIPE Conference
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• 2018.07a
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• pp.192-194
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• 2018

In this paper a new single-stage ac-dc converter with high frequency isolation and low components count is introduced. The proposed converter is constructed using two interleaved boost circuits in the grid side and non-regulating full bridge in the DC side. An optimized switching is implemented on the two interleaved boost circuits resulting in a ripple-free grid current without a ripple cancellation network; hence very small filter inductors are used. A simple and reliable closed-loop control system is easily implemented, since the phase-shift angle is the only independent variable. Moreover, current imbalance is avoided in the presented topology without current control loop in each phase. The proposed charger charges the battery with a sinusoidal-like current instead of a constant direct current. ZVS turn on of all switches is achieved throughout the operation in both directions of power flow without any additional components.

• Journal of Power Electronics
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• v.17 no.4
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• pp.991-1003
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• 2017

The conventional sliding mode control (CSMC) has a number of problems. It may cause dc output voltage ripple and it cannot guarantee the robustness of the whole system for a matrix rectifier (MR). Furthermore, the existence of a filter can decrease the input power factor (IPF). Therefore, a novel global sliding mode control (GSMC) based on a hyperbolic tangent function with IPF compensation for MRs is proposed in this paper. Firstly, due to the reachability and existence of the sliding mode, the condition of the matrix rectifier's robustness and chattering elimination is derived. Secondly, a global switching function is designed and the determination of the transient operation status is given. Then a SMC compensation strategy based on a DQ transformation model is applied to compensate the decreasing IPF. Finally, simulations and experiments are carried out to verify the correctness and effectiveness of the control algorithm. The obtained results show that compared with CSMC, applying the proposed GSMC based on a hyperbolic tangent function for matrix rectifiers can achieve a ripple-free output voltage with a unity IPF. In addition, the rectifier has an excellent robust performance at all times.