• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.10A
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• pp.965-970
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• 2005

In this paper, SPDT Tx/Rx MMIC switch applicable to IEEE 802.11a WLAN systems is designed and fabricated using a specific designed epitaxial layered pHEMT wafer and ETRI's $0.5{\mu}m$ pHEMT switch process. The SPDT switch exhibits a low insertion loss of 0.68dB, high isolation of 35.64dB, return loss of 13.4dB, power transfer capability of 25dBm, and 3rd order intercept point of 42dBm at frequency of 5.8GHz and control voltage of 0/-3V. The comparison of the measured performances with commercial products based on the GaAs pHEMT technology for low voltage operating at ${\pm}$ 3V/0V shows that the return loss is somewhat inferior to the commercial products and insertion loss is compatible with each other however, isolation characteristics are much better than in conventional chips. Based on these performances, we can conclude that the developed SPDT switch MMIC has an enough potential for IEEE802.11a standard 5 GHz-band wireless LAN applications.

• Proceedings of the Korean Information Science Society Conference
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• 1998.10a
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• pp.441-443
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• 1998

본 논문은 유무선 환경에서 ATM 멀티캐스트 서비스를 제공하기위한 방안으로서{{{{ { SM}^{2 }A }}}} 를 제안한다. 기존의ATM 멀티캐스트 서비스는 ATM자체의 제약으로 멀티캐스트 서비스가 제한적이며 비효율적이다. 한편, ATM의 중용한 응용으로서 인터넷서비스를 심각하게 고려해야하는데 {{{{ { SM}^{2 }A }}}}는 특히 인터넷 서비스를 제공하는데 적합한 구조를 갖도록 설계되었다.{{{{ { SM}^{2 }A }}}}는 기본적으로 양방향성 공유트리방식인 CBT(Core Based Tree)구조를 갖되 각 지역망 (Regional Network)에서 자체적인 코어스위치( Core Switch)를 보유함으로써 결과적으로 다중 코어 구조를 갖는다. 각 지역망을 잇기 위하여 PNNI 프로토콜을 이용하며 PGL(Peer Group Leader)에 가상 루트(Virtual Root) 및 가상 리프(Virtual Leaf)의 개념을 새로 도입한다. 멀티캐스트 통신의 경우 가장 문제되는 것이 셀끼워넣기(Interleaving)문제인데.{{{{ { SM}^{2 }A }}}}에서는 ITU-T표준 ATC(ATM Transfer Capability)인 ABT/IT(ATM Block Transfer/Immediate Transmission)

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.11a
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• pp.1415-1418
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• 2007

When a high voltage COS fuse becomes a short circuit by the over current, the impulse noise over 150 dB(A) with the strong pulse jet is radiated from the COS fuse of an electric transformer. For the purpose of the impulse noise reduction, in this study, a reactive type silencer with perforated panels are considered. The transmission loss of the silencer are calculated by transfer matrix method. The effect of the porosity, the distance between panels, and the number of perforated panel on the sound transmission loss is investigated and discussed.

• Rapid Communication in Photoscience
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• v.5 no.1
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• pp.1-7
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• 2016

Fluorescent receptors have gained much attention because of their usefulness in analysis and clarification of the roles of biomolecules in living systems. Molecular structures of the integrated type including that the receptor itself is fluorescent, and play an important role in having the functionality or selectivity of the fluorescent compounds. These spaced type fluorescent receptors are required to have special molecular design in order to transmit the information of molecular recognition to the fluorescent unit through the spacer unit. Compared with the spaced type fluorescent receptors, number of the integrated type receptors is limited due to the difficult molecular design and synthesis. Modification of alteration of the fluorophore frequently caused deterioration of the fluorescent property. Various spaced type and integrated type fluorescent receptors including switch on-off receptors are introduced in this article.

• IE interfaces
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• v.9 no.3
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• pp.120-142
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• 1996

Asynchronous Transfer Mode (ATM) is considered to be the most promising transfer technique for BISDN due to its efficiency and flexibility. Queueing theory has been playing a very important role in performance evaluation of ATM for the past few years. This paper is composed of two parts. The first part is concerned with the several basic concepts of ATM. The second part surveys queueing approaches in ATM performance evaluation. It deals with stochastic models which have been proposed for the three basic categories of traffic sources (voice, data, video), various queueing models for statistical multiplexer and switch, and priority strategies for buffer control schemes.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2009.05a
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• pp.321-323
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• 2009

When power failure occurs at multi-housing complex, auxiliary generator or emergency generator starts to provide power to households. This power is connected to emergency power ELB(Earth Leakage Breaker) at home distribution panel board and supplies power only for emergency light in living room but for heating system, refrigerator and other inevitable apparatuses that are in need of uninterruptible power. Since those domestic appliance are fed from common power line, they are inoperable during power failure. Our research is to resolve this problem by developing compatible relay-drive common/emergency-power ATS (automatic transfer switch) for home distribution panel board. In case of power failure, it transfers automatically and commences to provide power from emergency generator. Through this, Consumers can reach satisfaction where common power loads operate without any problem under both ordinary and power failure condition.

• Journal of Sensor Science and Technology
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• v.21 no.6
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• pp.413-419
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• 2012

A dynamic range extension technique is proposed based on a 3-transistor active pixel sensor (APS) with gate/body-tied p-channel metal oxide semiconductor field effect transistor (PMOSFET)-type photodetector using a feedback structure. The new APS consists of a pseudo 3-transistor APS and an additional gate/body-tied PMOSFET-type photodetector, and to extend the dynamic range, an NMOSFET switch is proposed. An additional detector and an NMOSFET switch are integrated into the APS to provide negative feedback. The proposed APS and pseudo 3-transistor APS were designed and fabricated using a $0.35-{\mu}m$ 2-poly 4-metal standard complementary metal oxide semiconductor (CMOS) process. Afterwards, their optical responses were measured and characterized. Although the proposed pixel size increased in comparison with the pseudo 3-transistor APS, the proposed pixel had a significantly extended dynamic range of 98 dB compared to a pseudo 3-transistor APS, which had a dynamic range of 28 dB. We present a proposed pixel that can be switched between two operating modes depending on the transfer gate voltage. The proposed pixel can be switched between two operating modes depending on the transfer gate voltage: normal mode and WDR mode. We also present an imaging system using the proposed APS.

• Journal of Applied Reliability
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• v.16 no.2
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• pp.162-170
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• 2016

Purpose: The purpose of this study was to analyze the failure modes of an auto transfer switch (ATS), determine the most common failure mechanisms, and iterate the design to improve reliability. Methods: We carried out failure mode and effect analysis (FMEA) to determine the failure modes and mechanisms. We identified the parts or modules that required improvement via two-stage quality function deployment based on FMEA, and improvements to reliability were monitored using the Gomperz growth model. Results: The main failure modes of the ATS were damage to, and deformation of, the stator / movable element due to repetitive movements. Five iterations of design modification were carried out, and the mean time to failure (MTTF) increased to 14,539 cycles, corresponding to 85% of the target MTTF. The Gompertz growth model indicates that the 10th iteration of design modification is expected to achieve the target MTTF. Conclusion: We improved the reliability of mechanical parts via failure mode analysis, and characterized the iterative improvements in the MTTF using the Gompertz growth model.

• Bulletin of the Korean Chemical Society
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• v.32 no.9
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• pp.3223-3228
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• 2011

To quantify the presence of mercuric ions in aqueous solution, double-stranded DNA (dsDNA) of poly(dT) was employed using a light switch compound, $Ru(phen)_2(dppz)^{2+}$ (1) which is reported to intercalate into dsDNA of a right-handed B-form. Addition of mercuric ions induced the dehybridization of poly(dT)${\cdot}$poly(dA) duplexes to form a hairpin structure of poly(dT) at room temperature and the metal-to-ligand charge transfer emission derived from the intercalation of 1 was reduced due to the dehybridization of dsDNA. As the concentration of $Hg^{2+}$ was increased, the emission of 1 progressively decreased. This label-free emission method had a detection limit of 0.2 nM. Other metal ions, such as $K^+$, $Ag^+$, $Ca^{2+}$, $Mg^{2+}$, $Zn^{2+}$, $Mn^{2+}$, $Co^{2+}$, $Ni^{2+}$, $Cu^{2+}$, $Cd^{2+}$, $Cr^{3+}$, $Fe^{3+}$, had no significant effect on reducing emission. This emission method can differentiate matched and mismatched poly(dT) sequences based on the emission intensity of dsDNA.

• The Transactions of the Korean Institute of Power Electronics
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• v.13 no.4
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• pp.278-286
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• 2008

This paper investigates the fault generation type and the cause of output interruptionsin bulky with $30^{\sim}500[KVA]$ double conversion UPS, and proposes the fault detection method to improve the reliability of power supply used in the critical load in industry. Identifies its existing way of detecting a quality of inverter output it to bypass when exceeds its expectation. Under a UPS managing system, when an inner (Power device, Controller, CPU) fault occurs it disrupts the power supply and these occurrences has been verified by the results of experiments and application results. To overcome these problems, the proposed method constructs independently a fault-detection, a bypass-control device and a triple power supply apart from the conventional UPS operation. Also the detection point is changed to the preceding of a circuit breaker, a reference of fault detection is modified to avoid any clash and the breaking equipment is attached to intercept a spread of accident. As a result of applications of these developed systems to 242 UPS which was installed purposefully to the communication power supply, the service errors has not occurred in the UPS for two years since 2006.