• Journal of the Korea institute for structural maintenance and inspection
• /
• v.16 no.2
• /
• pp.1-9
• /
• 2012

Reinforced concrete buildings will be deteriorated as passed time or effect of an earthquake, etc in main elements. In order to manage such cracks, time and efforts, expense, etc, are required. So micro lead switch sensors are embedding or bonding in flexible specimens, and these are smart elements for diagnostic crack damages by external force such as physical load, dynamic load, etc in this study. The monitoring to crack damages are studied using radio frequency system. If load is received on the center of flexible specimens, embedded and bonded lead switch sensors will be destroyed, and these become to send signals of damages at radio frequency system connected with lead switch sensors. This study is fundamental research of the diagnostic system for architectural elements using radio frequency.

• Journal of Power Electronics
• /
• v.10 no.4
• /
• pp.444-449
• /
• 2010

The generation of electric power using self excited induction generation (SEIG) is a viable option in remote and rural areas where grid electricity is not available. The generated voltage and frequency of these machines, however, varies with varying loads. This characteristic can be resolved either by adjusting the values of the excitation capacitance or by controlling the prime mover speed. Further, in a single-point constant power application, where the machines deliver a fixed amount of power, the electronic load controller (ELC) can be used to switch-in or switch-out a dump load whenever the consumer load decreases or increases respectively. This paper presents a detailed analysis and the design of a microcontroller based SEIG -ELC system intended for stand-alone pico hydro power generation. The simulated performance of the controller is supplemented by experimental results.

• Proceedings of the IEEK Conference
• /
• 1998.10a
• /
• pp.265-268
• /
• 1998

This paper evaluates the VSN(Virtual switch Network) characteristics in the internal call processing of IMT-2000 switching system, which is composed of VSN instead of ATM switch network. In results, internal call establishment delay is increased approximately 5.4msec than the conventional ATM switching system. The evaluated condition is the load 0.8, and the 100km distance between VSNs. It is confirmed that the VSN has the potentiality in the practical implementation.

• Proceedings of the KIPE Conference
• /
• 1998.10a
• /
• pp.663-667
• /
• 1998

This paper describes for reducing harmonic distortion on CO2 welding machine with nonlinear load characteristic using single-switch three-phase AC/DC converter. The low-order harmonic component amplitude of the phase current of single-switch three-phase discontinuous mode is calculated. Experimental results show that CO2 welding machine with single-switch three-phase AC/DC converter is effectively controlled with power factor correction for phase current during welding time.

• Proceedings of the Korean Information Science Society Conference
• /
• 2004.10c
• /
• pp.523-525
• /
• 2004

규모가 방대한 네트워크상에서 네트워크의 침입과 방어의 효과와 유용성을 알아보기 위해, 실존하는 네트워크상에서 직접 침입과 방어를 테스트하는 것은 많은 노력과 비용이 든다. 이와 같은 문제점을 극복하기 위해 인터넷 침입의 표현에 필요한 네트워크 침입 시뮬레이션을 하기 위한 SSFNet 확장 연구가 진행되었다. 본 연구는 SSFNet에 새로이 추가된 L4-Switch 모듈을 이전 연구에서 만들어진 모듈들과 함께 대규모 네트워크 환경에서 네트워크 침입 시뮬레이션을 테스트하였다. 본 시뮬레이션은 L4-Switch와 http클라이언트, http서비스를 제공하는 호스트들을 설정하고, load balancing이 잘 되었는지를 살펴보았다.

• Journal of the Institute of Electronics Engineers of Korea TC
• /
• v.40 no.11
• /
• pp.27-33
• /
• 2003

This paper proposes the efficient audit method for the distributed connection information in ATM switch. Based on this method, we design the periodic audit function by a system and immediate audit function by a operator's order. We evaluate the performance about the proposed Audit method. At the result of evaluation, We figure out that the load of call control processor is almost independent of a system load regardless of audit function operation. Therefore, we confirm that the proposed audit method nearly have an effect on the load of call control processor. The proposed audit method can reestablish a Mismatched connection information with a little load.

• Journal of Electrical Engineering and Technology
• /
• v.12 no.4
• /
• pp.1471-1483
• /
• 2017

The low-frequency characteristics of four-switch three-phase (FSTP) inverter are investigated in this paper. Firstly, a general space vector pulse width modulation (SVPWM) directly involved the neutral point voltage of DC-link is proposed, where no sector identifications and trigonometric function calculations are needed. Subsequently, to suppress the DC offset in the neutral point voltage, the relationship between the neutral point voltage and the ${\beta}-axis$ component of the load current is derived, and then a new neutral point voltage control scheme is proposed where no low pass filter is adopted. Finally, the relationship between the load power factor and the maximum linear modulation index of the FSTP inverter is revealed. Since the operational region for the FSTP inverter in low frequency is reduced by the enlarged amplitude of the neutral point voltage, a linear modulation range enlargement scheme is proposed. A permanent magnet synchronous motor with preset rotary speed serves as the low-frequency load of the FSTP inverter. Experimental results verify that the new neutral point voltage control scheme is effective in the deviation suppression of the neutral point voltage, and the proposed scheme is able to provide a larger linear operational region in low frequency.

• Proceedings of the KIEE Conference
• /
• 2005.07a
• /
• pp.377-380
• /
• 2005

In this paper, accelerated stress test(AST) for Magnetic Switch (MS) are applied to assure specified reliability of the products. Magnetic contactor that functions with over-current relay is called MS. Magnetic contactor closes and opens the motor load with ON/OFF switch of electronic contactor. It is also used for protecting and controlling the load. Magnetic contactor detects the over-current flow in the load with a over-current relay and disconnects the load by opening its control power. In this study, AST for product assembly are developed in order to improve the weak point so that increase the product reliability. Also we will show the basic information for the accelerated life test(ALT). The proposed AST results and procedures may be extended and applied to testing similar kinds of products to reduce test times and costs of the tests remarkably. Finally the results of this study will contribute to improving reliability of products and strengthening competitiveness of our products in the world markets.

• Proceedings of the KIEE Conference
• /
• summer
• /
• pp.354-356
• /
• 2004

This paper is the transient analysis for choosing the optimal SCR ratings of AC3 utilization category testing equipment(AC3 TE) used for electrical durability test for magnetic switch according to IEC60947-4 Annex B by utilizing EMTP -ATPDraw. Magnetic contactor closes and opens the motor load with ON/OFF switch of electronic contactor. It is also used for protecting and controlling the load. Magnetic contactor detects the over-current flow in the load with a over-current relay and disconnects the load by opening its control power. The key cost of AC3 TE is the SCR ratings. The more decreases SCR ratings, the more decreased the cost is, but it is impossible to ensure the reliability. On the other hand, the more increases SCR ratings, the more increased the cost is. Thereupon, in this paper after the testing circuit is simulated by using EMTP-ATPDraw the SCR ratings will be applied in order to guarantee the testing reliability of PT&T(Power Testing and Technology institute in LG Industrial Systems Co.,Ltd.).

• The Transactions of the Korean Institute of Power Electronics
• /
• v.25 no.3
• /
• pp.188-194
• /
• 2020

This paper presents a high-efficiency Switch Mode Line Transformer (SMLT) composed of load-shared dual modules, which is based on the AC/AC LLC resonant converter. Given that the conventional adaptor is usually composed of two power stages, namely, the PFC and DC/DC converters, its system size can be increased according to the output power. However, given that the proposed SMLT can separate the PFC converter from the adaptor, the size reduction of the system can be achieved. Meanwhile, the SMLT with a single module has the limit of the size reduction because of a high resonant current. Thus, it can be configured with dual or multiple modules to reduce the resonant current. Then, their load sharing can be guaranteed by only the proposed transformer structure without an extra current controller. The validity of the proposed converter is proven through a 850-W prototype.