• Proceedings of the KIEE Conference
• /
• 1995.07a
• /
• pp.95-97
• /
• 1995

A superconducting current generator, or a superconducting rectifier(SCR) is used as a current source to energize a superconducting magnets in SMES, MRI. We selected a full-wave SCR among various SCR models and analyzed its operational characteristics by computer simulation. In process of pumping the current, the improvement of performance is dependent on how much bigger the open resistance of the switch is in comparison to load coil impedance when one of two switches become active. Faster transfer can he seen in resistive commutation mode by shortening the time elapsed for the resistance to arrive at certain level from zero state. Although recovery time for the switch has no direct effect on current pumping, optimal switch design is needed to increasing operational frequency.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2005.10a
• /
• pp.661-665
• /
• 2005

The muffler reducing the exhaust noise and vibration from the engine influence on the engine performance. Recently the semi-active muffler was developed and adopted to the actual use in consideration of the cost and technical side for noise and vibration. This study is about the recently developed semi-active muffler. This paper attempt to analyze the dynamic stress field on the gate plate by using the finite element methods. According to the analysis of the Exhaust Variable Valve, its spring has the most influence on its operation compare with effects of other components. The design parameters of the Exhaust Variable Valve such as the spring displacement, diameter, coil number, free angle and so forth were used.

• Journal of Biomedical Engineering Research
• /
• v.20 no.5
• /
• pp.537-544
• /
• 1999

자기공명영상시스템의 경사자계코일을 영구자석의 자극에 부착할 경우 경사자계의 분포가 변하고 코일의 인덕턴스가 증가하는 현상이 생긴다. 본 논문에서는 이러한 자극효과를 고려하여 평면형 경사자계코일을 설계하는 방법을 제시하였다. 제사한 방법에는 자극 효과를 거울 전류로 모델링하였고, 모델링한 거울 전류를 고려하여 경사자계코일의 인덕턴스를 최소화하는 방법을 구했다. 또한 실제 상황과 가장 흡사한 자계 분포를 만들어주는 거울 전류의 크기를 구하기 위해 유한요소법을 적용하였다. 제시한 방법으로는 설계된 경사자계코일은 종래의 설계된 경사자계 코일에 비해 우수한 성능을 보였다.

• Proceedings of the KIPE Conference
• /
• 2016.11a
• /
• pp.161-162
• /
• 2016

본 논문에서는 권선 사이의 자계결합도 변동을 고려하여 자기공진 방식의 보조권선을 포함하는 전기차 충전용 무선전력전송회로의 설계기법을 제시한다. 전기차 충전용 무선전력전송회로를 설계하기 위해서는 회로의 동작주파수가 표준규격에 의해서 일정범위로 제한되고 1차측과 2차측 권선의 정렬상태에 따라서 자계결합도가 변동할 수 있다는 점이 고려되어야 한다. 본 논문에서는 동작주파수의 제한범위 및 자계결합도의 변동을 고려하여 1차측에 보조권선을 포함하는 자기공진형 무선전력전송회로의 설계기법을 제시한다.

• Progress in Superconductivity and Cryogenics
• /
• v.23 no.2
• /
• pp.19-23
• /
• 2021

We have studied the breaking system that combines a resistive superconducting fault current limiter (SFCL) and a DC circuit breaker for DC fault current. To verify the design of the 15 kV DC SFCL, which was driven from the previous work, a 500 V DC system was built and a scale-down SFCL were manufactured. The manufactured SFCL module was designed as a bifilar coil which is a structure that minimizes inductive reactance. The manufactured SFCL module has been experiment to verify characteristics of the current-limiting performance in the DC 500 V system. Also, the manufactured FCL module was combined with the DC circuit breaker to be experimented to analyze the breaking performance. As a result of the experiment, when SFCL was combined to the DC circuit breaker, the energy dissipation received by the DC circuit breaker was reduced by up to 84% compared to when the DC circuit breaker operates alone. We are preparing methods and experiments for the optimal method for much higher performance as a future work.

• Journal of Drive and Control
• /
• v.17 no.4
• /
• pp.87-96
• /
• 2020

In this study, a variable elasticity spring was applied to improve the pressure control precision of conventional relief valves. The equilibrium equation of the forces acting on the valve poppet was derived; it is demonstrated that matching the elastic rate of the pressure-adjusting coil spring to the equivalent elastic rate of the flow force improved the pressure override. The procedures that were used to design the variable elasticity spring are presented, and some applications of the variable elasticity spring are also introduced. Computer simulations were used to analyze three cases: a poppet-closed flow force structure, a poppet-open flow force structure with a constant elasticity spring, and a structure containing a variable elasticity spring. It is confirmed that the pressure control precision of the relief valve can be significantly improved upon by applying a variable elasticity spring to the poppet-open flow force structure.

• 제어로봇시스템학회:학술대회논문집
• /
• 2001.10a
• /
• pp.98.1-98
• /
• 2001

An actuator using a permanent magnet and solenoid is proposed and designed in this paper. Its design concept is composed of a driving force generation, a guide mechanism, and a symmetric structure. At first, Driving Force generation uses a concept that is a change efflux by using a permanent magnet and solenoid. A permanent flux is generated by a permanent magnet. Changeable flux is created by a variable current flowing through coil such the solenoid. The direction of this flux is changed due to current flowing through coils. The combination of permanent and changeable fluxes make various flux densities between yokes of moving part and fixed yokes. And then, the flux densities create forces(F), which are used to drive this actuator, in lower and upper gap. In this actuator ...

• Progress in Superconductivity and Cryogenics
• /
• v.10 no.4
• /
• pp.13-17
• /
• 2008

This paper presents experimental and characteristic analysis of hgh-$T_c$ eater-triggered witch using coated conductor (CC) in liquid and gas helium. The high temperature superconducting insert coil which can be installed in a low temperature superconducting (LTS) magnet has been proposed and researched to generate higher magnetic field for MR. Since CC could be an attractive option for HTS insert, it is important to research he characteristics of heater-triggered switch employing CC. We performed the heater test and constructed simulation model using finite element method (FEM.) We performed a protection test and observed normal zone propagation (NZP) signals to evaluate the witch with protection of magnet.

• Proceedings of the KIPE Conference
• /
• 2020.08a
• /
• pp.196-198
• /
• 2020

본 논문은 SiC MOSFET의 단락 검출을 위한 고정밀 Rogowski 코일 회로 설계 방법을 제안한다. 설계 방법을 제안하기 위해 먼저 Rogowski 코일의 기본 구성인 적분기를 실제 시스템 요구 사양에 맞추어 설계한다. 설계한 회로의 성능 확인을 위하여 DPT (double pulse test)를 실시하며, test 결과 분석을 통해 문제점을 파악하고 전류 센싱 정밀도 향상을 위해 입출력 필터 설계 및 Rogowski 코일 턴 수를 변경한다. 변경한 각 조건들에 대하여 DPT를 진행하고 각 test 결과를 기반으로 Rogowski 코일 회로 설계 방안을 제안한다.

• Nuclear Engineering and Technology
• /
• v.56 no.1
• /
• pp.275-282
• /
• 2024

Lead bismuth eutectic (LBE) is used as coolant for MicroURANUS, a small marine nuclear power plant, and this coolant is transported in the plant by an electromagnetic pump. Given the considerable heat generated by the electromagnetic pump, the cooling of the pump is essential. This study compared air cooling and water-cooling methods and found that the maximum temperatures during air and water cooling were 640 K and 372 K, respectively. These findings were utilized to design an electromagnetic pump with water-cooling. The maximum temperature of the pump was lower than the boiling point of water; thus, the pump did not require a separate pressurization. Consequently, the resistance problem of the coil and the deformation problem of the material caused by generated heat can be solved through water-cooling.