• 한국수소및신에너지학회논문집
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• 제34권2호
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• pp.132-140
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• 2023

In this study, rotary magnet holder (RMH) was manufactured to analyze the ion transport effect according to the rotating magnetic field for the hydrogen production efficiency by alkaline water electrolyte. In the experiment, the voltage signal according to the magnet arrangement inside the RMH, the rotation speed, and the rotation time was measured using the voltage measurement module. As a result of the voltage signal measurement experiment, the average potential difference increased as the rotation speed of the RMH increased. Through the results of the voltage signal measurement experiment, the most efficient magnet arrangement (case 2) was applied to the RMH to conduct a water electrolysis experiment. A 20% NaOH aqueous solution was filled in the electrolytic cell, and a direct current 2 V constant voltage was applied to measure the current value according to the RMH rotation to compare the hydrogen generation amount. When rotating at 100 RPM, the hydrogen production efficiency increased by 8.06% compared to when not rotating. Considering the area exceeding +25 mA, which was not measured at the beginning of the experiment, an increase in hydrogen production of about 10% or more can be expected.

• 한국멀티미디어학회논문지
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• 제14권1호
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• pp.133-143
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• 2011

본 연구에서는 햅틱 정보를 이용하여 시각장애인들이 이동할 방향을 촉각적으로 제시할 수 있는 휴대용 네비게이션 시스템을 제안한다. 시각장애인들에게 촉각정보를 전달하기 위해 솔레노이드, 영구자석 및 탄생 스프링으로 이루어진 촉감 모듈을 개발하고 제안하는 시스템에 탑재한다. 또한 진동모터를 탑재하여 제안한 시스템의 특정 지역에서 진동이 발생하여 시스템의 표면을 타고 다른 곳으로 흘러가는 2D 이동진동과 기법을 제안한다. 촉감모듈과 이동진동파는 제안하는 시스템 내에서 사람의 손가락과 손바닥을 각각 촉각적으로 자극함으로 방향을 제시한다. 제안한 시스템이 촉각적으로 사용자에게 방향성을 제시할 수 있는가를 증명하기 위하여 실험을 수행한다. 본 연구의 실험 결과로부터 제안하는 시스템은 사용자에게 실시간으로 이동할 방향을 전달함을 알 수 있다.

• 디지털융복합연구
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• 제10권11호
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• pp.331-335
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• 2012

핸드폰에 사용되는 카메라의 발달로 자동초점용 렌즈에 대한 많은 연구가 진행되어 왔다. 다양한 종류의 자동초점용 액추에이터 중에서 VCM(Voice Coil Motor)이 가장 많이 사용되고 있다. 이 VCM은 자석, 코일, 요크 등의 모양에 따라서 구성되는 자계의 흐름을 달리하여 원하는 수준의 자동초점 조절이 가능한 핸드폰용 카메라가 만들어지고 있다. 본 연구에서는 유한요소 해석프로그램인 ANSYS$^{TM}$를 이용하여 산업체에서 사용되는 다양한 구조의 렌즈 중 가장 경제적인 모델을 선택하여 전자기 분석을 수행하였다. 이 전자기 해석을 통하여 효율적인 렌즈 모듈 설계 방법을 제시한다.

• 전력전자학회논문지
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• 제24권2호
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• pp.71-77
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• 2019

This study proposes a circulating current reduction method that uses high-frequency voltage compensation when carrier phase difference occurs between two inverters in MSIS. In MSIS, inverters are configured in parallel to increase power capacity and to increase efficiency by using inverters only as needed. However, in the parallel inverter structure, circulating current is inevitably generated. Circulating current increases the stress on the switch, adversely affects the current control performance, and renders load sharing difficult. The proposed method compensates for the output voltage reference of the slave module by using the high-frequency voltage so that the switching pattern of each module is matched even in asynchronous carriers. The validity of the proposed method is verified by simulations and experiments with 600 W IPMSM.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2007년도 춘계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.147-149
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• 2007

This paper presents design results of anultra-small actuator for auto focus or optical zoom function of mobile phone cameras. The consideration of the actuator is tubular type having a large hole in its center to arrange some optical lenses. The stator consists of 3-phase windings, and the mover is designed to an Nd injection permanent magnet(PM) which magnetized with multi-pole polar pattern. From the numerical analysis that taking into account the magnetizing pattern of the PM, the thrust of the designed actuator is about 40mN with the outer diameter of 7mm.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제55권12호
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• pp.653-660
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• 2006

In this paper, dynamic simulation results for modules of a magnetically-levitated(Maglev) vehicle are presented. The mathematical dynamic models for the Maglev vehicle are firstly derived. The Maglev system consists of one vehicle, two half-bogies, one guideway, four secondary suspensions, eight electromagnets and levitation control systems. Also, the dynamic characteristics are analysed by using the derived models. Finally, two simulations such as reference airgap step change of 1mm and rail step change of 1mm, are carried out. The dynamic simulation results are shown to testify the developed dynamic simulation program. From the results, we can see the possibility of the dynamic simulation program to develop a new Maglev vehicle system.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년도 제37회 하계학술대회 논문집 B
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• pp.625-626
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• 2006

This paper presents the new simulation model for the performance analysis of Surface-Mounted Permanent Magnet Synchronous Motor(SMPMSM) Drive System which is integrated with a controller and a power converter. To enhance reusability and compatibility, the system model is expressed by the association of independent sub-modules reflecting the real physical construction. This concept allows another independent sub-module to be effectively inserted in the model for the comprehensive analysis of larger systems such as a Machine Tool and HEV. The developed model which is composed of MATLAB/Simulink's basic blocks can rapidly analyze not only the entire behavior of system, but also the functional relationship between each components for the effective development of controller.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2013년도 전력전자학술대회 논문집
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• pp.386-387
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• 2013

This paper provides a comparison of high power semiconductor devices in 5MW-class Permanent Magnet Synchronous Generator (PMSG) Medium Voltage (MV) wind turbines. High power semiconductor devices of IGBT module type, IGBT press-pack type, and IGCT of both 4.5kV and 6.5kV are considered in this paper. Benchmarking is performed based on neutral-point clamed 3-level back-to-back type voltage source converter supplied from grid voltage of 4160V. The feasible number of semiconductor devices in parallel is designed through the loss analysis considering both conduction and switching losses under the given operating conditions of 5MW-class PMSG wind turbines, particularly for the application in offshore wind farms. The loss analysis is confirmed through PLECS simulations. The comparison result shows that IGBT press-pack type semiconductor device has the highest efficiency and IGCT has the lowest cost factor considering the necessary auxiliary components.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 하계학술대회 논문집 D
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• pp.3210-3212
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• 2000

We designed and manufactured 300MHz NMR RF Transceiver. NMR system is composed of NMR Spectrometer, Superconductive Magnet and Pulse Programmer, GUI. NMR RF Transceiver is composed of transmitter, receiver, frequency synthesizer. T/R switch, main power amp., RF coil. To phase modulation, transmitter is composed of mixer, splitter and combiner et al. To weak signal detection, receiver is composed of pre-amp., filter, mixer et al. Each module is manufactured PCB. And installed NMR system to detect chemical component of specimen. In result, we can get the information of specimen.

• KIEAE Journal
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• 제17권1호
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• pp.63-68
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• 2017

Purpose: Various studies to solve the problem of increased energy consumption in the buildings are being carried out recently. Especially, the economic feasibility and insulation performance of the air-cap have been verified so that various studies regarding the reduction of building energy consumption have been carried out. However, previous studies regarding the air-cap were only carried out based on the verification of its insulation performance according to the size and attachment position of the air-cap. Therefore, the purpose of this study is to suggest a detachable air-cap module for improving the performance of the windows, evaluate the performance based on cooling, heating and light environments and verify its effectiveness through a real-scale testbed. Method: In this study, the energy saving performance in the circumstance where there is no attachment of an air-cap (Case 1), the circumstance where there is the attachment of air-cap on the glass surface of window (Case 2) and the circumstance where there is the attachment of an air-cap on the window frame (Case 3) were compared in order to verify the performance of the detachable air-cap module (Case 4), and the electricity consumption of cooling, heating and lighting equipment to maintain the appropriate indoor temperature and Illuminance for each case was calculated and utilized as indicators for the performance evaluation. Result: The result of this study is as follows. 1) In this study, the detachable air-cap module which was easily detachable through the principle of the magnet was suggested. 2) When Case 4 is applied, the electricity consumption of cooling and heating equipment can be reduced by 27.5%, 13.2% and 3.4% in comparison with Case 1, Case 2 and Case 3 respectively. 3) When the air-cap is applied to the window, the lighting energy consumption increases by 4 % in comparison to the non application of the air-cap, and this factor or aspect should be considered when applying the air-cap. 4) According to the performance evaluation result in consideration of cooling, heating and light environments, Case 4 demonstrates an energy saving ratio of 22.6%, 10.6% and 2.7% in comparison to Case 1, Case 2 and Case 3 respectively, indicating that it is effective for improving the performance of windows.