• 한국항만경제학회지
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• 제24권3호
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• pp.23-35
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• 2008

현행 접안료 부과방법은 부두건설비용과 무관하게 사용료를 부과하고 있으므로 부두건설비용을 제대로 회수하지 못하는 문제점이 있다. 본 논문에서는 부두건설비용 배분문제에 협조적 게임이론을 응용함으로써 컨테이너부두의 건설비용 보전을 위한 접안료 부과방법을 제시하였다. 연구결과 부산항 컨테이너부두의 경우 선박간에 상호보조(cross subsidy)가 발생하는 것으로 분석되었다. 2만톤 미만 선박은 현행방법이 유리한 반면 2만톤 초과선박은 샤플리밸류에 의한 비용배분이 유리한 것으로 나타났다. 따라서 부두건설비용을 회수하기 위한 사용료 인상뿐만 아니라 각 선박별로 상호보조를 완화시킬 수 있도록 접안료 부과방법을 개선할 필요가 있다는 시사점을 얻었다. 현행방법을 그대로 유지하는 상태에서 일괄적으로 사용료를 인상하는 방법은 비용보전의 문제는 해결할 수 있지만, 그 경우에도 상호보조의 문제는 여전히 남게 된다. 본 연구는 공정하고 효율적인 접안료 부과방법으로서 협조적 게임이론을 응용한 비용배분방법을 제안한다.

• Journal of electromagnetic engineering and science
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• 제17권4호
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• pp.191-196
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• 2017

Microwave wireless power transmission (MWPT) is a promising technique for low and medium power applications such as wireless charging for sensor network or for biomedical chips in case with long ranges or in dispersive media such. A key factor of the MWPT technique is its efficiency, which includes the wireless power transmission efficiency and the radio frequency (RF) to direct current (DC) voltage efficiency of RF-DC converter (which transforms RF energy to DC supply voltage). The main problem in designing an RF-DC converter is the nonlinear characteristic of Schottky diodes; this characteristic causes low efficiency, higher harmonics frequency and a change in the input impedance value when the RF input power changes. In this paper, rather than using harmonic termination techniques of class E or class F power amplifiers, which are usually used to improve the efficiency of RF-DC converters, we propose a new method called "optimal input impedance" to enhance the performance of our design. The results of simulations and measurements are presented in this paper along with a discussion of our design concerning its practical applications.

• 한국초전도ㆍ저온공학회논문지
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• 제20권3호
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• pp.15-20
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• 2018

No-insulation (NI) pancake magnets are fabricated using Rare earth-Barium-Copper Oxide (REBCO) coated conductor (CC) tapes, which enabled a very compact magnet in the aspects of high critical current density ($J_c$) and high mechanical strength by removing insulation and allowing thinner stabilizer. They have also advantages such as self-quench protection. Therefore, it does not need quench detection and protection that can be very challenging in a high critical temperature ($T_c$) superconducting magnet technology. Recently, it was reported that the NI REBCO CC magnets have some drawbacks of long charging time and high field ramp loss which will be a concern in the operation of cryocooled magnets. These issues are related to the turn-to-turn contact resistivity and can be released by managing it. This is also closely related to the activity of reducing the contact joint resistance in the case of CC joints for long length CC fabrication. Therefore, in this study, the turn-to-turn contact resistance ($R_c$) at the CC contact part of differently stabilized CC tapes was measured. The behaviors of $R_c$ at CC contact parts according to the applied contact pressure were investigated. The range of $R_c$ measured for CC tapes adopted will provide fundamental data for design and fabrication of the CC NI coils.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 추계학술대회 논문집 전기물성,응용부문
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• pp.197-200
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• 2005

As Plasma Immersion ion Implantation (PIII) using a conducting grid is very useful to reduce the effect of capacitance and charging in surface modification. If the bias voltage applied to the conducting grid is in the range of hundreds of volts, the effects of surface charge and space charge substantially affect the incident ion energy and ion current to the surface. In this paper, through an 1d and a 2d PIC simulation the time varying formation of the space charge and surface charge is analyzed. Experiment with the optimally designed grid on the basis of the simulation results is conducted, and the results of both cases with grid and without grid are compared. In our work with Poly Urethane(PU), the improvement of adhesion is yielded by increasing surface roughness and decreasing Si component of PU.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2008년도 제39회 하계학술대회
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• pp.1038-1039
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• 2008

This paper proposes a base models of Hybrid railway vehicle power system. A powered system with fuel cell is regarded as a high current and low voltage source. The design parameters of the system should be chosen by taking into account the characteristics of the fuel cell, so the costs of the power system at given operating conditions can be reduced. Currently, no integrated simulation has been approached to analyze interrelated effects. Therefore, the base models of power conversion system with a PEM fuel cell/IPT system for hybrid powered system that includes the PEM fuel cell stack, DC/DC converter are developed. Concept of bidirectional converter for super capacitor charging system is presented.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2015년도 제46회 하계학술대회
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• pp.990-991
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• 2015

To drive a magnetron injection gun, thsi paper decribes a design, fabrication and analysis results of proposed compact capacitor charging power supply (CCPS) formed resonant full-bridge inverter for electron gun power supply (EGPS). EGPS needs the -40 kV output voltage and 280 kW output power for few seconds continuously and have to be designed for the rise and fall time to be less than 1 ms with the ripple stability of output voltage of lower than 1%. In order to meet the requirements, we used eight resonant full-bridge modules operated in parallel. Each resonant full-bridge module can supply the current of 0.9 A and the voltage of 40 kV, and is operated by N-phase shift switching pattern. In this paper, we present the design, simulation and test results of interleaved CCPS.

• 조명전기설비학회논문지
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• 제26권7호
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• pp.16-22
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• 2012

With the increase of consumption of new renewable energy, the use of Electric Double Layer Capacitor(EDLC) is being gradually widened as the next generation energy storage device. In order to expand the market of EDLC which is recently receiving a lot of attraction as a new promising area, development of a charge/discharge cycle tester to measure and test performance, is essential. Therefore, this research designed a circuit to measure capacity and internal resistance and a circuit to measure voltage maintenance properties, based on EDLC's basic charging/discharging properties so it is able to measure the state of charge and discharge at high speed. When evaluating performance characteristics, the 5[V]/100[A] prototype-EDLC charge/discharge testing system developed for this research showed ${\pm}0.1$[%] of accuracy of voltage and current measurement. It was also proved that the developed charge/discharge testing system for EDLC can be applied to the actual industry, when testing the entire system using a program produced for data monitoring and acquisition.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2014년도 제46회 동계 정기학술대회 초록집
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• pp.240.2-240.2
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• 2014

Characteristics of pulse-discharged plasma in liquid and its biological applications to proteins are investigated by making use of high voltage Marx generator. The Marx generator has been consisted of 5 stages, where each charging capacitor is $0.5{\mu}F$ to generate a high voltage pulse with rising time of $1{\mu}s$. We have applied an input voltage of 6 kV to the each capacitor of $0.5{\mu}F$. The high voltage pulsed plasma has been generated inside a polycarbonate tube by a single-shot operation, where the breakdown voltage is measured to be 7 kV, current of 1.2 kA, and pulse width of ${\sim}1{\mu}s$ between the two electrodes of anode-cathode made of stainless steel, which are immersed into the liquids. For the investigation of the influence of pulsed plasma on biomolcules, we have focused on the amino acids, DNA, proteins, cell and cholesterol.

• Journal of Power Electronics
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• 제16권5호
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• pp.1981-1989
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• 2016

Battery diagnosis is vital to battery-based applications because it ensures system reliability by avoiding battery failure. This paper presents a novel intelligent battery charger with an online diagnosis function to circumvent interruptions in system operation. The charger operates in normal charging and diagnosing modes. The diagnosis function is performed with the impedance spectroscopy technique, which is achieved by injecting a sinusoidal voltage excitation signal to the battery terminals without the need for additional hardware. The impedance spectrum of the battery is calculated based on voltage excitation and current response with the aid of an embedded digital lock in amplifier in a digital signal processor. The measured impedance data are utilized in the application of the complex nonlinear least squares method to extract the battery parameters of the equivalent circuit. These parameters are then compared with the reference values to reach a diagnosis. A prototype of the proposed charger is applied to four valve-regulated lead-acid batteries to measure AC impedance. The results are discussed.

• Journal of Communications and Networks
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• 제7권2호
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• pp.192-206
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• 2005

Integration of mobile networks and Internet has started with 2.5 generation of mobile cellular networks. Internet traffic is today dominant traffic type worldwide. The hanger for higher data rates needed for data traffic and new IP based services is essential in the development of future wireless networks. In such situation, even 3G with up to 2 Mbit/s has not provided data rates that are used by Internet users with fixed broadband dial-up or through wired local area networks. The solution to provide higher bit rates in wireless access network has been found in wireless LAN although initially it has been developed to extend wired LAN into wireless domain. In this paper, we propose and describe a solution created for interoperability between mobile cellular network and WLAN. The integration between two networks, cellular and WLAN, is performed on the authentication, authorization, and accounting, i.e., AAA side. For that purpose we developed WLAN access controller and WLAN AAA gateway, which provide gateway-type access control as well as charging and billing functionalities for the WLAN service. In the development process of these elements, we have considered current development stadium of all needed network entities and protocols. The provided solution provides cost-effective and easy-to-deploy PLMN-WLAN Internetworking scenario.