• The Transactions of the Korean Institute of Electrical Engineers B
• /
• v.51 no.10
• /
• pp.581-586
• /
• 2002

To improve the current waveform of diode rectifiers, we propose a new operating principle for the voltage-doubler diode rectifiers. In the conventional voltage-doubler rectifier circuit, relatively large capacitors are used to boost the output voltage, while the proposed circuit uses smaller ones and a small reactor not to boost the output voltage but improve the input current waveform. A circuit design method is shown by experimentation and confirmed simulation. The experimental results of the proposed diode rectifier satisfies the harmonic guide lines. A high input power factor of 97(%) and an efficiency of 98[%] are also obtained. The new rectifier with no controlled switches meet the harmonic guide lines, resulting in a simple, reliable and low-cost at-to dc converters in comparison with the boost-type current-improving circuits. This paper proposes a nonlinear impedance circuit composed by diodes and inductors or capacitors. This circuit needs no control circuits and switches, and the impedance value is changed by the polarity of current or voltage. And this paper presents one of these applications to improve the input current of capacitor input diode rectifiers. The rectifier using the nonlinear impedance circuit is constructed with four diodes and four capacitors in addition to the conventional rectifiers, that is, it has eight diodes and five capacitors, including a DC link capacitor. It makes harmonic components of the input current reduction and the power factor improvement. Half pulse-width modulated (HPWM) inverter was explained compared with conventional pulse width modulated(PWM) inverter. Proposed HPWM inverter eliminated dead-time by lowering switching loss and holding over-shooting.

• Proceedings of the KIPE Conference
• /
• 2014.11a
• /
• pp.9-10
• /
• 2014

최근 신재생에너지 및 전기자동차, 통신 IT 서버 전원 및 가전기기 등의 발전에 따라 고 전력밀도(High Power Density), 고 응답(Fast Transient Response) 및 고정밀(Tight Regulation) 출력제어를 위한 다 출력 절연형 DC/DC 컨버터가 개발 및 연구되고 있다. 본 논문에서는 개별적인 정밀제어를 요구하는 다 출력 DC-DC 컨버터에 대한 내용으로 위상천이(Phase-shift) DC-DC 컨버터와 LLC 공진컨버터 제어개념을 하나의 주회로를 사용하여 위상천이제어(Phase-shifted Modulation, PM)와 가변주파수제어(Variable Frequency Modulation, FM)를 통해서 개별적으로 정밀 제어할 수 있는 하이브리드 다 출력 3레벨 DC-DC 컨버터에 관한 내용이다.

• Electronics and Telecommunications Trends
• /
• v.24 no.5
• /
• pp.74-86
• /
• 2009

기존 전력망에 정보통신기술을 접목하여 전력망의 신뢰성, 효율성, 안전성 향상을 꾀하고자 하는 스마트 그리드의 비전은 태양력 및 풍력과 같은 신재생 에너지, 전기자동차(EV), 배터리와 같은 저장 장치, 수요반응 등으로 대표된다. 스마트 그리드에서는 에너지원, 전력, 통신, 소프트웨어, 컴퓨팅, 가전기기, 반도체 등 다양한 기술이 복합적으로 얽혀 있으며, 사업자 및 정책도 기술요소만큼 복합적이다. 본 고에서는 전력 정보를 양방향 실시간으로 유통함으로써 에너지 자원을 거래하는 모습까지 포함하는 차세대 전력망 기술인 스마트 그리드의 개념 및 특성, 관련 기술 파악을 통하여 중요성을 살펴보고, 관련된 국내외 정책 및 시장동향, 국내외 기술개발 동향에 대해서 기술하고자 한다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2001.10a
• /
• pp.537-540
• /
• 2001

As giving IP on electric home appliance like as TV, Air-conditioner, etc., with the development of electric products and home networking, it has been possible to communicate through the Internet. In this paper, we proposed and developed the system which is possible to control the commercial vending machine using embeded internet card through internet. We implemented the basic circuit and application program for TCP/IP communication program by Java applet.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2015.10a
• /
• pp.1090-1092
• /
• 2015

IT 기술의 급격한 발전에 따라 다양한 분야에서 자동화가 이루어지면서, 가정 내의 각종 기기들을 유기적으로 결합하여 편리함과 안전 확보를 꾀하는 홈 오토메이션 시스템도 빠르게 실용화되고 있다. 홈 오토메이션 기술을 활용하면 외부에서도 가스 및 전기, 디지털 도어록 등을 제어할 수 있다. 기존의 디지털 도어록은 대부분 비밀번호 입력을 통한 문의 개폐를 지원하므로 보안상의 허점이 있다. 본 논문에서는 사용자가 스마트폰 애플리케이션을 이용하여 디지털 도어록을 원격으로 개폐하고 문 앞의 대상을 감지해 사진을 촬영하고 사용자에게 알림으로써 편리성과 보안 기능이 강화된 스마트 도어록 시스템을 설계하고 구현한다.

• Proceedings of the KIPE Conference
• /
• 2007.07a
• /
• pp.95-97
• /
• 2007

This paper studies on operating limit curve of low voltage electric machinery with respect to source voltage variation or sag. Also, it discusses electric machine and compensation equipment design methodology based on voltage quality effect assessment technology. Voltage quality standards, such as SEMI47, CBEMA, ITIC curve are regarded to examine the relation between time constants of load and sagging time of sag generator, the load(low voltage electric machinery) study. Voltage sag characteristics of loads, time constant and sag relation voltage-time operating limits are tested and verified.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.21 no.3
• /
• pp.107-116
• /
• 2007

The introduction of new renewable energy is going on increase with the second plan of the Korean Government "Technology Development, Utilization and Popularization of New Renewable Energy". In general, it is connected to the power system due to the nature of it's source characteristics but it's interconnection operation impacts on the power system planning and operation. The operation schemes of the existing power distribution system are based on the unidirectional power flow, but unidirectional power flow changes to bidirectional power flow due to the interconnection operation of new renewable energy. It degrade the existing protection coordination system and power quality of the power distribution system. Thus, the technical evaluation process of the interconnection of new renewable energy are necessary. In this paper, the characteristics of the existing automatic recloser and sectionalizer are reviewed and interconnection capacity evaluation method of the DR(distributed resources) in the existing automatic recloser-sectionalizer protective coordination system are proposed.

• Resources Recycling
• /
• v.21 no.4
• /
• pp.26-34
• /
• 2012

Recently, the recovery of resources from waste material of manufacturing electric and electronic equipment has been investigated. It is very important to extract metallic components from electric and electronic manufacturing processes with the view point of recycling of the used resources as well as an environmental protection. In this paper, open/registered patents of US, JP, EP, and KR and SCI journal related to metal recovery technologies from wastes produced in the electric and electronic manufacturing processes between 1975~2011 were reviewed. Patents and papers were collected using key-words searching and filtered by filtering criteria. The trends of the patents and papers were analyzed by the years, countries, companies, and technologies.

• Journal of the Microelectronics and Packaging Society
• /
• v.11 no.4 s.33
• /
• pp.37-41
• /
• 2004

As mobile communication devices use wide bands for large data transmission, Low Temperature Co-fired Ceramic(LTCC) has been a candidate for module substrate, for it provides better electrical properties and enables various embedded passive devices compared to conventional PCB. The LTCC, however, has applied in limited area because of non-uniform shrinkage. Hybrid heating was developed to raise sample temperature uniformly in a short period of time This leads to unidirectional sintering which enables sample to be sintered layer by layer from the bottom, resulting in more stable shape of interconnection at the top surface of the sample than conventional electric furnace heating. When sintering properties of substrate and electrical/mechanical properties of interconnection were compared, hybrid heating showed possibility to be applicable to substrate miniaturization and interconnection densification superior to electric furnace heating.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.16 no.4
• /
• pp.38-45
• /
• 2002

This paper describes the technical issues of the domestic standard and guideline for lightning protection systems in order to propose the countermeasures in damage of computer and electronic equipments due to lightning surges. The relationship between the current flow in the down conductor and the current flow in the steel conduit surrounding the down conductor was investigated as a function of the installation method of down conductors. Also the experiments were conducted to evaluate the influences of the skin effect on the down conductor systems. As a result, when the down conductor were bonded to the steel conduit, the down conductor and the steel conduit act as one conductor, so much mure lightning current flows in the steel conduit than in the copper down conductor because of the skin effect and choking effect. Therefore to reduce the adverse effects such as the electrostatic induction and side flashes caused by the potential rise of down conductors due to lightning currents, it is extremely effective to bond the down conductor to the steel conduit and steel frame of structures.