• The Journal of Korean Institute of Communications and Information Sciences
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• v.24 no.8B
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• pp.1401-1411
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• 1999

Due to the increase of multimedia services, multicasting is considered as important design factor for ATM switch. To resolve the traffic expansion problem that is occurred by multicast in multistage interconnection networks, this paper proposes the multicast switch using a high-speed bus and a shared memory switch. Since the proposed switch uses a high-speed time division bus as a connection medium and chooses a shared memory switch as a basic switch module, it provides good port scalability. The traffic arbitration scheme enables internal non-blocking. By simulation we proves a good performance in the data throughput and the cell delay.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.21 no.8
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• pp.2033-2042
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• 1996

In this papre, we describe a recently implemented echo canceller for digital cellular communication of Code Division Multiple Access(CDMA) that features time sharing of digital signal processor(DSP) over four channels in one DSP to reduce per channel costs. In the Public Land Mobile Network(PLMN), it is important to cancel the echo reflected from the Public Switched Telephone Network(PSTN) side. In case of digital mobile system, the round-trip delay of the echo is in excess of about 180 milliseconds due to frame-by-frame voice coding. It is necessary to cancel the echo in PLMN. We have developed a multi-channel echo canceller tht operates with Time Switch Module in a Mobile Switching Center(MSC). The general echo canceller needs PCM trunk interface circuits and the tone detection and disabling circuits, but the multi-channel echo canceller linked with Time Switch Module does not need them. Therefore we could develop the effective and economical echo canceller.

• Proceedings of the KIPE Conference
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• 2005.07a
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• pp.14-16
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• 2005

In this paper, a new control scheme to use 6-switch inverters for 3-phase switched reluctance motors (SRM) is proposed. Compared with the conventional asymmetric converter topology, it can minimize the entire system size and cost and can increase the efficiency. Therefore, it may have a new topology for SRM to compete the other ac motors, such as induction motors, brushless dc motors, and soon. The validity of the proposed method is verified by simulation, and experimental results.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.07b
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• pp.1217-1219
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• 2003

상용화되어 있는 이동통신 기기의 Front-end 부분은 듀플렉서와 필터를 포함하는 수동소자로 구성되어 있다. 듀플렉서의 임피던스 정합선로는 전송선로 이론으로부터 설계하며, 단순하게 ${\lambda}=1/4$ 파장 길이의 정합 선로를 설치하는 것이기 때문에 정합선로를 이용한 듀플렉서 성능을 극대화하기 위한 설계의 융통성이 없는게 현실이다. 이런 문제점을 해결하기 위하여 집중소자(lumped element)인 R L C를 탄성 표면파 듀플렉서 대신 스위치 모들에 적용하게 된다면 여러 가지 다양한 형태의 회로를 구현할 수 있고 회로망 내에 위치하는 집중소자의 정격을 최적화하여 스위치 모듈의 성능을 향상시킬 수 있는 가능성이 있다. 본 연구에서는 $900 MHz{\sim}2.2 GHz$의 대역에서 소형화 집적화에 적용 가능한 디바이스를 개발하기 위하여 고주파, 저진압, 저손실 스위치 모듈의 제조와 구성되는 커패시터와 인덕터의 제조와 특성에 관하여 연구하였다.

• Journal of Sensor Science and Technology
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• v.20 no.2
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• pp.77-81
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• 2011

This paper presents a single-pole eight-throw(SP8T) switch based on proposed a radio-frequency(RF) microelectromechanical systems (MEMS) switches. The proposed switch was driven by a double stop(DS) comb drive, with a lateral resistive contact. Additionally, the proposed switch was designed to have tapered signal line and bi-directionally actuated. A forward actuation connects between signal lines and contact part, and the output becomes on-state. A reverse actuation connects between ground lines and contact part, and the output becomes off-state. The SP8T switch of 3-stage tree topology was developed based on an arrangement of the proposed RF MEMS switches. The developed SP8T switch had an actuation voltage of 12 V, an insertion loss of 1.3 dB, a return loss of 15.1 dB, and an isolation of 31.4 dB at 6 GHz.

• Journal of the Korea Society of Computer and Information
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• v.10 no.5 s.37
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• pp.123-132
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• 2005

In this Paper, we present an improvement of switch node for wavelength multiplex optical network. Currently because of quick increase of internet traffic a big network capacity is demanded. Wavelength multiplex optical network Provides the data transfer of high speed and the transparent characteristic of the data. Therefore optic network configuration is the most powerful technology in the future. It will be able to control the massive traffic from the optical network in order to transmit the multimedia information of very many quantify. Consequently the node where the traffic control is Possible, is demanded. The optical switch node which manages efficiently the multiple wavelength was Proposed. This switch is composed of a optical switch module for switching and a wavelength converter module for wavelength conversion. It will be able to compose the switch fabric without optical/electro or electro/optical conversion using optical MEMS(Micro Electro Mechanical Switches) module. Finally, we present the good test result regarding the operational qualify of the switch fabric and the performance of optical signal from the switch node. The proposed switch node of the optic network will be able to control the massive traffic with all optical.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.21 no.4
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• pp.362-370
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• 2010

In this paper, a compact RF Front-end module for Wireless Fidelity(Wi-Fi) and Worldwide Interoperability for Microwave Access(WiMAX) applications is realized by low temperature co-fired ceramic(LTCC) technology. The RF Front-end module is composed of three LTCC band-pass filters, a Film Bulk Acoustic Resonator(FBAR) filter, fully embedded matching circuits, an SPDT switch for mode selection, an SPDT switch for Tx/Rx selection, and an SP4T switch for band selection. The parasitic elements of 0.2~0.3 pF are generated by the structure of stacking in the top pad pattern for DC block capacitor of SPDT switch for mode selection. These kinds of parasitic elements break the matching characteristic, and thus, the overall electrical performance of the module is degraded. In order to compensate it, we insert a parallel lumped-element inductor on capacitor pad pattern for DC block, so that we obtain the optimized performance of the RF Front-end module. The fabricated RF front-end module has 12 layers including three inner grounds and it occupies less than $6.0mm{\times}6.0mm{\times}0.728mm$.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.53 no.3
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• pp.142-147
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• 2004

In this study, We developed the microprocessor based controller for Auto Section Switch(ASS). This is installed at consumer's medium-high voltage(load capacity is below 4,000 kVA) switchgear. This function is cooperate with protection device of fault section and automatically dividing the section. And It is designed by Air putter type extinction structure and adopt the mechanism and breaking part module of existing Load Breaker Switch. In addition, We successfully conducted the operation test and checked main function of proto-type.

• Proceedings of the IEEK Conference
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• 2001.06a
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• pp.155-158
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• 2001

A 640Gb/s high-speed ATM switching system that is based on the technologies of advanced MCM, 0.25um CMOS and optical WDM interconnection is fabricated for future N-ISDN services. A 40 layer, 160mm$\times$114mm ceramic MCM realizes the basic ATM switch module with 80Gbps throughput. The basic unit ATM switch module with 80Gb/s throughput. The basic unit ATM switch MCM consists of in 8 chip advanced 0.25um CMOS VLSI and 32 chip I/O Bipolar VLSIs. The MCM employs an 40 layer, very thin layer ceramic MCM and a uniquely structured closed loop type liquid colling system is adopted to cope with the MCM's high-power dissipation of 230w. The MCM is Mounted on a 32cm$\times$50cm mother board. A three stage ATM switch is realized by optical WDM interconnection between the high-performance MCM.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.36D no.3
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• pp.1-11
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• 1999

It is now common practice to utilize the quadrature RF coils to improve the signal-to-noise ratio (SNR) in the Magnetic Resonance Imaging (MRI) System. In addition, to make such an available SNR improvement, it is mandatory to use a well-designed quadrature coupler, which facilitates a perfect 3-dB coupling and quadrature-phase shift. However, the four ports matching condition has to be well considered during the RF excitation and the signal detection period. This work investigates the effects of such a mismatching condition (especially, due to patient) from the analysis, simulation, and real implementation and firstly proposes dynamic loading technique for a quadrature coupler and transmitting/receiving switch module to minimize a patient mismatching and enhance a system reliability. Also, we designed and implemented the quadrature coupler and transmitting/receiving switch module using microstrip. As a result, the SNR of our MRI system using the microstrip quadrature coupler and transmitting/receiving switch module with dynamic load increases 3 dB compared with the old one using USA quadrature switch. Also, the power capability of quadrature coupler and transmitting/receiving switch module is 5-kw peak power. Considering power loss and reduction of size, we used a RT/duroid 6010 substrate with high permittivity and for simulation we use Compact Software.