• The Transactions of the Korean Institute of Electrical Engineers A
• /
• v.54 no.6
• /
• pp.315-322
• /
• 2005

In this article, 1 would like to explore the estimation method of time-varying voltage sags in large industrial systems considering the short circuit contributions of rotating machines. For the power distribution system of KEPCO(Korea Electric Power Corporation), the magnitude of initial symmetrical short circuit current is generally not changed. However, in industrial systems which contain a number of rotating machines, the magnitude of voltage sag is generally changed from the initial to the clearing time of a fault due to the decreasing contribution of rotating machines for a fault current. The time-varying characteristics of voltage sags can be calculated using a short circuit analysis that is considered the time-varying fault currents. For this, the prediction formulations of time-varying voltage sags are proposed using a foreign standard. The proposed method contains the consideration of generator and motor effects. For the test of proposed formulations, a simple system of industrial consumer is used for the comparison conventional and proposed estimation method of voltage sag characteristics.

• Journal of the Korean Institute of Telematics and Electronics C
• /
• v.34C no.12
• /
• pp.37-42
• /
• 1997

A new temperature and supply-insensitive CMOS current reference circuit was designed and tested. Te temperature insensuitivity was achieved by eliminating the mobility dependence term through the multiplication of two current components, one which is proportional to mobility and the other which is inversely proportional to mobility, by using a newly designed CMOS square root circuit. The CMOS sqare root circuit was derived from its bipolar counterpart by operating the MOS transistors in the subthreshold region. The supply insensitivity was achieved by using an internal voltage generator. Te test chip was designed ans sent out for fabrication by using a 2.mu.m double-poly double-metal n-well CMOS technology. When an external voltage source was used for the square root circuit, the maximum variation and the average temperature sensitivity were measured to be 3% and 21.4ppm/.deg.C, respectively, for the temperature range of -15~130.deg.C. The maximum current variation with supply voltage was measured to be 3% within the commerical supply voltage range of 4.5~5.5V at 30.deg. C.

• Journal of Power Electronics
• /
• v.6 no.3
• /
• pp.253-263
• /
• 2006

A high performance and low cost single switch current fed energy recovery circuit (ERC) for an alternating current (AC) plasma display panel (PDP) is proposed. Since it is composed of only one power switch compared with the conventional circuit consisting of four power switches and two large energy recovery capacitors, the ERC features a simpler structure and lower cost. Furthermore, since all power switches can be switched under soft switching operating conditions, the proposed circuit has desirable merits such as increased reliability and low switching loss. Specifically, there are no serious voltage notches across the PDP with the aid of gas discharge current compensation, which can greatly reduce the current stress of all inverter switches, and provide those switches with the turn on timing margin. To confirm the validity of proposed circuit, its operation and performance were verified on a prototype for 7-inch test PDP.

• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.21 no.4
• /
• pp.31-38
• /
• 2022

In this study, we designed and manufactured an intelligent gripper-control device to safely grip unknown objects. The gripper control device consists of a DSP circuit, power supply circuit, communication circuit, and amplifier circuit diagrams. The DSP is used because the values of the 3-axis force sensor to which the gripper is attached are measured and calculated at high speeds. The gripping force is determined based on this value, and the object must be safely gripped with the determined value. A basic characteristic test of the control device of the manufactured intelligent gripper was conducted, and it was confirmed that it operated safely.

• Proceedings of the KIPE Conference
• /
• 2011.11a
• /
• pp.303-304
• /
• 2011

본 논문은 HVDC System의 컨버터를 구성하는 Thyristor 밸브의 스위칭동작을 테스트하는 합성시험회로의 기본동작을 분석한 내용에 대해 기술하고 있다. 합성시험회로(STC : Synthetic Test Circuit)는 HVDC System의 컨버터가 동작할 때 각 Thyristor 밸브에 나타나는 턴-온 전류와 턴-오프 전압을 인위적으로 공급하여 정상동작 여부를 시험할 수 있는 모의실험회로를 의미한다. 본 연구에서는 PSCAD 프로그램을 이용하여 2kV, 200A급 Thyristor를 테스트하기 위한 합성시험회로의 시뮬레이션 모형을 개발하고 그 동작을 분석하였다. 개발한 합성시험회로의 시뮬레이션 모델은 향후 IEEE와 IEC 규정에 만족하는 새로운 합성시험회로를 개발하는데 참고 자료로 활용 될 것으로 기대된다.

• Proceedings of the KIEE Conference
• /
• 2005.11b
• /
• pp.49-51
• /
• 2005

The saturation of transformer for short-circuit test suppress the peak current value during the test. And such phenomenon effect on the test results occasionally. This paper deals with the induction of the formula to restore the peak current value from the measured data.

• Tribology and Lubricants
• /
• v.19 no.6
• /
• pp.335-341
• /
• 2003

Recently, the automotive industry is being developed rapidly. On this, a demand of high quality performance­test­machine is increased too. But it is progressive technology that must be combined hydraulic, mechanic and electronic technologies. To construct this system, the design of oil hydraulic circuit, interface skill between sensor and personal computer, data acquisition & display system and integrated control are very important skill. Moreover, reliable data is obtained with vacuum system and complex heat exchange system. Therefore, in this study, we designed a performance­test­machine by using above key technologies and we also made a integrated PC control system using personal computer which is more progressive and flexible method than PLC control.

• Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
• /
• 1999.02a
• /
• pp.146-149
• /
• 1999

A 30kVA superconducting generator has been designed, developed and successfully tested recently. The design is based on 2-dimensional electromagnetic field analysis. The rotor has been wound with superconducting wire of Nb-Ti alloy. The stator has the air-gap type armature windings. Open-circuit test, short-circuit test and lamp load test have been conducted. The details of design program, design, machinebuilding, test results and conclusions are given in this paper.

• Journal of Korean Society for Quality Management
• /
• v.25 no.1
• /
• pp.135-141
• /
• 1997

The Copper-Clad Laminate (CCL) is a main electronic component of specialtype printed circuit boards (PCBs) such as Silver Through Hole PCB. This CCL should have high reliability under the aging test, and usually the test is done at a higher temperature (110-$150^{\circ}C$) than the normal. Then, this test condition of high temperature may cause such quality problems as hole eccentricity and reduction of distance between part holes. After measuring the CCL shrinkage affected by temperature, the correction factor of a press mold was a, pp.ied to solve these problems. The results showed that the tolerance of hole pitch(${\pm}$$100{\mu}m$) was satisfactory and the internal and external failure costs were reduced by 55%.

• Proceedings of the KIEE Conference
• /
• 1994.07b
• /
• pp.1385-1387
• /
• 1994

For the development of the 25.8kV outdoor GCB (Gas - Circuit - Breaker), which have a surge surpression performance in closing & opening of circuit and a high reliability performance, we have developed the 25.8kV gas bushing first of all in KOREA. After manufacturing of 25.8kV/2000A gas bushing, we carried out the dimension & visual test and electrical & mechanical test and we have got the favorable test-results. And it was put together real outdoor GCB, and then we carried out type test at KERI and have confirmed the performance of this bushing.