• Korean Journal of Optics and Photonics
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• v.22 no.6
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• pp.276-282
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• 2011

We performed experiments on Hong-Ou-Mandel type two-photon interference with frequency entangled photon pairs at 1.5 ${\mu}m$ telecommunication band generated through femtosecond pulsed spontaneous parametric down-conversion. Two different angular frequencies ${\omega}_1$ and ${\omega}_2$ were selected using CWDM(coarse wavelength division multiplexing) filters at the output ports of the interferometer. The coincidence counting rates were measured with varying path-length difference between the two interferometer arms to observe the two-photon interference patterns of spatial beating. The obtained visibilities in the net coincidence were close to the theoretical limit of 100%.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.9A
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• pp.835-843
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• 2010

Energy spreading transform (EST) based equalization is a very effective technique to remove inter symbol interference (ISI) in frequency selective channel. EST based system uses cyclic prefix (CP) similar to orthogonal frequency division multiplexing (OFDM) system. Since CP is a redundancy, it degrades the data transmission rate. RISIC is an algorithm that removes an inter block interference (IBI) caused by insufficient CP length and reconstructs CP. In this paper, we propose a system that combines the existing EST system with quadrature phase shift keying (QPSK) modulation and RISIC algorithm to enhance the efficiency of the transmission. Also we extend the proposed system to 16 quadrature amplitude modulation (QAM) modulation. The proposed system is shown to performance close to matched filter bound (MFB) even with insufficient CP.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.23 no.9
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• pp.67-74
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• 2009

For the surge currents like lightning currents containing high frequency components and the abnormal currents having high frequencies which cause the EMI(Electromagnetic interference) problems for the electronic devices and communication instruments, the linear grounding electrodes have the significantly composite impedance characteristics which are dependent on the frequency of the applied current. The impedance of a grounding electrode is not lowered by expanding the dimension of the grounding electrode, and the length of grounding electrode having the minimum value of the grounding impedance for each condition of frequency and soil characteristics is existent, and it is defined as Critical length. In this paper, the critical lengths for the vertically and horizontally-buried grounding electrodes are calculated by using the distributed parameter circuit model. The propriety of the simulations has been confirmed by comparing the simulated results with the measured results.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.49 no.2
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• pp.1-8
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• 2012

We propose a new frame length control scheme for cognitive radio systems. In the proposed algorithm, the property that the probability of a primary packet arrival continually increases as time elapses during the primary user's idle period is utilized. When reducing the secondary frame length in accordance with the increasing primary packet arrival probability, spectrum sensing is conducted more frequently as time elapses and the primary packet arrival is detected more quickly. We obtain the optimal frame lengths by maximizing the secondary throughput while satisfying the interference constraint. Numerical results show a significant throughput enhancement via the frame length control.

• The Research Journal of the Costume Culture
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• v.22 no.2
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• pp.198-208
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• 2014

The purpose of this study was to investigate the demand for functional elements of sports climbing shirts. Questionnaire survey data were collected from adult (n=53) and adolescent (n=55) sports climbers. The questionnaire explored respondents' sports climbing activities and need for functional design features of sports climbing shirts. Their design preferences and purchasing value were also investigated. The results showed that respondents regarded ergonomic design and the use of intelligent material as important elements of expert-level sports climbing shirts. Compared to adolescent, adult respondents were more susceptive to functional design elements such as suitability for climbing motions and ease of dressing or undressing. Also, adult sports climbers were more likely than adolescents to prefer shirts that are tightly fit at the chest. Neither adults nor adolescents favored shirts design that is tightly fit at the neck or armpit. The regular shirts length not covering hips and sleeve length ending at the wrist were preferred. The collar stand should not hit the chin. Adult climbers preferred ergonomically designed sleeves on the back shoulder. Adults and adolescents had different preferences for the front neck zipper length. Adults preferred long front zipper length at chest. These findings suggest that sports climbing shirts should have functional features to prevent interference with climbing movements and improve convenience and stability.

• Proceedings of the IEEK Conference
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• 2000.11b
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• pp.305-308
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• 2000

In this paper, the 7${\times}$7 MMI Multiplexer is designed. The 1${\times}$7 Splitter and the 7${\times}$7 Coupler are designed and the phase-matched away length is determined. Then this result is confirmed by the simulation considering the intermode coupling. The MMI Multiplexer has The 14nm operating wavelength region, the 2nm wavelength spacing and the 1${\times}$3$\textrm{mm}^2$ size.

• Proceedings of the KIEE Conference
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• 2001.07a
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• pp.346-348
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• 2001

This paper analyze the interference problems, especially AC corrosion when the gas pipeline is buried with power cable in the same submarine tunnel. This paper present the results of the study about AC corrosion, limitation of safety voltage, modeling of power cables, gas pipeline and grounding systems, analysis of induction voltage according to various circumstance, soil resistivity, length of tunnel. and so on.

• Molecules and Cells
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• v.19 no.1
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• pp.1-15
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• 2005

Eukaryotes produce various types of small RNAs of 19-28 nt in length. With rapidly increasing numbers of small RNAs listed in recent years, we have come to realize how widespread their functions are and how diverse the biogenesis pathways have evolved. At the same time, we are beginning to grasp the common features and rules governing the key steps in small RNA pathways. In this review, I will summarize the current classification, biogenesis, action mechanism and function of these fascinating molecules.

• 전자공학회논문지 IE
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• v.47 no.2
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• pp.54-59
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• 2010

This paper suggests a new data link protocol with an adaptive frame length control scheme for wireless data networks which is subject to errors that occur with time variance. We analyze the proposed scheme under a two-state markov block interference(BI) model. Numerical results show that the proposed scheme can achieve high throughput performance for both dense and diffuse burst noise channels.

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 1986.10a
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• pp.198-200
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• 1986

In this paper, the optical modem for data link realization is designed with the advantages of optical fiber : large handwidth, no electromagnetic interference, high speed and long-haul communications. Biphase cording format is used for the sync, and async, transmissions. Modem interface conform to the CCITT V.24 standard for the compatibility with existing systems. 0/E and E/0 converters are designed using LED-APD pair for long wave length and LD-APD for short wave length, respectively. As a result, the system is capable of transmitting at any bps within dc to 200Kbps in async, and at 1200bps up to 57.6Kbps in sync. transmission.