• Proceedings of the KSR Conference
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• 2007.11a
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• pp.1946-1950
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• 2007

Switch rail is a very important part on the railway track, which not only accounts for the safety of the passing trains but also greatly influences the speed of the train. The higher the speed and the loads of the train the more it demands on the properties of the switch rail. Research shows that the higher mechanical properties of switch rail the longer the service life. Induction heat treatment is a good way of improving the mechanical properties of metallic materials. But the switch rail's section area changes gradually across the lengthways, which is difficult for induction heating especially for the small section. And the mechanical property of small section of the switch rail is the most important for its service life. The induction heat treatment used past always brings the low hardness on small section which can cause low service life of switch for wearing, or too high hardness because of martensite microstructure which can cause the shelling or even breaking of the switch rail. To prolong the service life of switch rail by higher mechanical properties, we researched the improved induction heat treatment for switch rail by adjusting speed of heating, and adopting compressed air cooling. The results showed that switch rail obtain almost the same high hardness across the length way after the improved induction heat treatment, which is very helpful to extend the service life of switch rail.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• v.12B no.1
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• pp.37-43
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• 2002

This paper proposes a new zero-current switching (ZCS) pulse-width modulation (PWM) switch cell that has no additional conduction loss of the main switch. In this cell, the main switch and the auxiliary switch turn on and turn off under zero current condition. The diodes commutate softly and the reverse recovery problems are alleviated. The conduction loss and the current stress of the main switch are minimized, since the resonating current for the soft switching does not flow through the main switch. Based on the proposed ZCS PWM switch cell, a new family of dc to dc PWM converters is derived. The new family of ZCS PWM converters is suitable for the high power applications employing IGBTs. Among the new family of dc to dc PWM converters, a boost converter was taken as an example and has been analyzed. Design guidelines with a design example are described and verified by experimental results from the 2.5㎾ prototype boost converter operating at 40KHz.

• Journal of Communications and Networks
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• v.17 no.3
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• pp.286-295
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• 2015

Avionic databuses fulfill a critical function in the connection and communication of aircraft components and functions such as flight-control, navigation, and monitoring. Ethernet-based avionic databuses have become the mainstream for large aircraft owning to their advantages of full-duplex communication with high bandwidth, low latency, low packet-loss, and low cost. As a new generation aviation network communication standard, avionics full-duplex switched ethernet (AFDX) adopted concepts from the telecom standard, asynchronous transfer mode (ATM). In this technology, the switches are the key devices influencing the overall performance. This paper reviews the avionic databus with emphasis on the switch architecture classifications. Based on a comparison, analysis, and discussion of the different switch architectures, we propose a new avionic switch design based on a time-division switch fabric for high flexibility and scalability. This also merges the design concept of space-partition switch fabric to achieve reliability and predictability. The new switch architecture, called space partitioned shared memory switch (SPSMS), isolates the memory space for each output port. This can reduce the competition for resources and avoid conflicts, decrease the packet forwarding latency through the switch, and reduce the packet loss rate. A simulation of the architecture with optimized network engineering tools (OPNET) confirms the efficiency and significant performance improvement over a classic shared memory switch, in terms of overall packet latency, queuing delay, and queue size.

• Journal of Power Electronics
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• v.1 no.2
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• pp.71-77
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• 2001

This paper proposes a new zero-current switching (ZCS) pulse-width modulation (PWM) switch cell that has no additional conduction loss of the main switch. In this cell, the main switch and the auxiliary switch turn on and turn off under zero current condition. The diodes commutate softly and the reverse recovery problems are alleviated. The conduction loss and the current stress of the main switch are minimized, since the resonating current stress of the main switch are minimized, since the resonating current for the soft switching does not flow through the main switch. Based on the proposed ZCS PWM switch cell, a new family of DC to DC PWM converters is derived. The new family of ZCS PWM converters is suitable for the high power applications employing IGBTs. Among the new family of DC to DB PWM converters, a boost converter was taken as an example and has been analyzed. Design guidelines with a design example are described and verified by experimental results from the 2.5 kW prototype converter operating at 40 kHz.

• Journal of Communications and Networks
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• v.18 no.3
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• pp.523-530
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• 2016

We use both theoretical analysis and simulations to study the impact of crosspoint-queued (CQ) buffer size on CQ switch throughput and delay performance under different traffic models, input loads, and scheduling algorithms. In this paper, we present the following. 1) We prove the stability of CQ switch using any work-conserving scheduling algorithm. 2) We present an exact closed-form formula for the CQ switch throughput and a non-closed-form but convergent formula for its delay using static non-work-conserving random scheduling algorithms with any given buffer size under independent Bernoulli traffic. 3) We show that the above results can serve as a conservative guide on deciding the required buffer size in pure CQ switches using work-conserving algorithms such as the random scheduling, under independent Bernoulli traffic. 4) Furthermore, our simulation results under real-trace traffic show that simple round-robin and random work-conserving algorithms can achieve quite good throughput and delay performance with a feasible crosspoint buffer size. Our work reveals the impact of buffer size on the CQ switch performance and provides a theoretical guide on designing the buffer size in pure CQ switch, which is an important step toward building ultra-high-speed switch fabrics.

• Journal of Korean Institute of Industrial Engineers
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• v.26 no.2
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• pp.136-145
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• 2000

The objective of this study is to evaluate the human performance relating to the layouts of the two different hand switch types with two and three buttons in the nuclear power plants. Using a computer simulation, the cognitive performance for the hand switch layouts was measured on the basis of response and task completion times. Comparative analyses were performed with three different layouts representing the current switch arrangements in the Yonggwang nuclear plants 5 and 6 and Ulchin 3 and 4, respectively. Statistical analyses revealed that the performance of the two-buttoned switch layouts was found to be better than those of the three-buttoned switch. Furthermore, the superiority of the two-buttoned switch type is consistent regardless of various layout types. These results imply that the difference of the cognitive performance can be attributable to the switch types rather than to the switch layouts. Therefore, from the cognitive perspective, the two-buttoned switch type is recommended for future power nuclear plants.

• Proceedings of the KIPE Conference
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• 2009.11a
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• pp.155-157
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• 2009

This paper proposed a soft switching boost converter with an auxiliary circuit, and a modified control method for reduction of switch stress. The proposed converter applies an auxiliary circuit, which is added to the conventional boost converter and used to achieve soft switching for both a main switch and an auxiliary switch. The auxiliary circuit consist of a resonant inductor and two capacitors, an auxiliary switch. The main switch is operated ZVS turn-on, turn-off also auxiliary switch is operated ZCS turn-on, ZVS turn-off. The proposed soft switching boost converter has lower switch loss and higher efficiency than conventional soft switching boost converter.

• Transactions on Electrical and Electronic Materials
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• v.17 no.1
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• pp.7-12
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• 2016

This paper proposes a metal contact RF MEMS switch which utilizes a see-saw mechanism to acquire a switching action. The switch was built on a quartz substrate and involves vertical deflection of the beam under an applied actuation voltage of 5.46 volts over a signal line. The see-saw mechanism relieves much of the operation voltage required to actuate the switch. The switch has a stiff beam eliminating any stray mechanical forces. The switch has an excellent isolation of −90.9 dB (compared to − 58 dB in conventional designs ), the insertion of −0.2 dB, and a wide bandwidth of 88 GHz (compared to 40 GHz in conventional design ) making the switch suitable for wide band applications.

• 연구논문집
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• s.29
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• pp.57-67
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• 1999

This paper presents the status quo of the development of a piecewise bendable switch system for the urban transit MagLev. MagLev system as well as railroad requires switch systems to reach its destination. Requirements of the switch system for commercial lines are high speed operation satisfying about 2-3 minute headway and system reliability, etc. Parallel moving type switch system was installed on the test track of urban transit MagLev in KIMM. In this system, switch operation from one position to another can be done in about 90 seconds. Therefore, we concluded that this system can not satisfy the headway for the commercial lines. We decided to develop a high speed piecewise bendable switch system in which switching can be done in 20 seconds. Designed switch system is very complicated in view of operating mechanism. It consists of 11 segmented girder beams driven by hydraulic cylinders. To gain the idea of a piecewise bendable switch system, we manufactured and tested a 1/5 scale switch model. We are going to construct a full scale piecewise bendable switch system next year.

• Journal of the Microelectronics and Packaging Society
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• v.4 no.2
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• pp.79-83
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• 1997

본 연구에서는 휴대용 전화기 및 무선 LAN 의 핵심부품인 RF-Switch Module의 초소형화 설계기술, 표면실장기술, 고주파설계기술, 소형화 SMD기술, Test 기술 및 RF-Switch Module 활용기술 등을 개발하였으며 RF-Switch Module의 설계기반 마련 및 대외 경쟁력 있는 RF-Switch Module의 초소형화 기술을 확보하였다.