• Bulletin of the Korean Space Science Society
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• 2010.04a
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• pp.35.5-36
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• 2010

현재 국내에는 90여개소 이상의 GPS 상시관측소가 운영되고 있으며, 측지, 측량, 항법, 군사, 과학 연구 등 다양한 분야에 활용되고 있다. 상시관측소의 정확한 위치 정보를 결정하고 사용자에게 제공하는 것은 매우 중요한 일이다. GIPSY-OASIS II(GPS Inferred Positioning System-Orbit Analysis and Simulation Software II, 이하 GIPSY라 칭함)는 고정밀 GPS 데이터 처리 프로그램으로 2008년 6월을 기해 GIPSY 5.0버전으로 업데이트 되었다. 이에 따라 안테나 위상중심변동량(phase center variation) 절대보정(absolute calibration) 모델, GMF(global mapping function) 등 최신 오차 모델 적용이 가능해 졌다. 이 논문에서는 GIPSY 5.0을 이용하여 국내 GPS 상시관측소의 정밀 좌표와 속도를 산출하고, 기존 공시좌표와 비교하였다. 그 결과 수평, 수직방향으로 최대 1~2cm의 좌표 변화가 나타났다.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.57 no.4
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• pp.431-436
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• 2008

We have extended an absolute evaluation method to obtain the ratio error and phase displacement of a current transformer (CT) up to primary current of 40,000 A by measuring four parameters of equivalent circuit in CT. The method was applied to CTs under test with the current ratios in the range of 5,000 A / 5 A - 40,000 A / 5 A. The ratio error and phase displacement of the CTs under test obtained in this study are consistent with those measured at the national institutes in Canada and Germany using the same CTs under test within an expanded uncertainty (k = 2) in the overall current ratios.

• Journal of Navigation and Port Research
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• v.36 no.6
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• pp.475-480
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• 2012

In order to establish eLoran (enhanced Long Range Navigation) system, it needs the advancement of receiver, transmitter, data channel addition for Loran information, differential Loran sites for compensating Loran-c signal and ASFs (Additional Secondary Factors) database, etc. In addition, the precise synchronization of transmitting station to the UTC (Coordinated Universal Time) is essential if Loran delivers the high absolute accuracy of navigation demanded for maritime harbor entrance. For better timing synchronization to the UTC among transmitting stations, it is necessary to measure and monitor the transmission delay of the station, and the correction information of the transmitting station should be provided to the user's receivers. In this paper we presented the measurement method of absolute delay of Pohang Loran transmitting station and developed a time delay measurement system and a phase monitoring system for Loran station. We achieved -2.23 us as a result of the absolute phase delay of Pohang station and the drift of Loran pulse of the station was measured about 0.3 us for a month period. Therefore it is necessary to measure the delay offset of transmitting station and to compensate the drift of the Loran signal for the high accuracy application of PNT (Positioning, Navigation and Timing).

• The Journal of the Acoustical Society of Korea
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• v.16 no.5
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• pp.76-82
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• 1997

The paper describes simulations and experimental results using a measuring system which utilizes the acoustic holographic method in order to exactly estimate an absolute position of a sound source. The measuring surface is installed to satisfy with a far field to the sound source and is composed of linear arrayed seven microphones. A measurement is simultaneously recorded by a reference microphone setting up a neighbour sound source and the linear arrayed seven microphones which are moved to the same interval. An absolute position of sound source is estimated by the cross-spectrum method to the received sounds between a reference and the measuring microphones. Phase differences of each microphone and time delays during scanning are compensated to the reference microphone and the measuring time of the first column. An optimal interval for each microphone in the measuring surface is decided by a numerical simulation. A source signal makes use of a sinusoid, and S/N ratio is 30dB in the experiment. The optimal microphone's interval in the simulation and the experiment is decided in order to satisfy with the Nyquist space sampling condition related to the wave length of 2kHz sinusoid. Mainlobe width of a estimated 3D hologram in the case of 2kHz source signal is decreased to 87% and 30% in comparison to 500Hz and 1kHz, and then a valid of simulation results is confirmed. Therefore, we verified a utilization of the study for a sound source estimation using 3ㅇ acoustic holographic method.

• Journal of Sensor Science and Technology
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• v.9 no.4
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• pp.316-326
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• 2000

A new signal processing algorithm for white light interferometry has been proposed and investigated theoretically. The goal of the algorithm is to determine the absolute optical path length of an interferometer with very high precision (<< one optical wavelength). The algorithm features cross-correlation of interferometer fringe scans and hypothesis testing. The hypothesis test looks for a zero order fringe peak candidate about which the cross-correlation is symmetric minimizing the uncertainty of misidentification. The shot noise limited performance of the proposed signal processing algorithm has been analyzed using computer simulations. Simulation results were extrapolated to predict the misidentification rate at Signal to-Shot noise ratio (SNR) higher than 31 dB. Root-mean-square phase error between the computer-generated zero order fringe peak and the estimated zero order fringe peak has been calculated for the changes of three different parameters (SNR, fringe scan sampling rate, coherence length of light source). Results of computer simulations showed the ability of the proposed signal processing algorithm to identify the zero order fringe peak correctly. The proposed signal processing algorithm uses a software approach, which is potentially inexpensive, simple and fast.

• Korean Journal of Cognitive Science
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• v.23 no.3
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• pp.409-424
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• 2012

The purpose of the present study was to examine if perception of visual coordination pattern is consistent with the prediction of the HKB model (Haken, Kelso, Bunz, 1985). In addition, this study aimed to see if an additional sensory information using a grid background stabilizes perception of coordination pattern. Participants joined one of two experimental groups, Normal background and Grid background, to participate the pattern recognition training session and the pattern judgment test session. Participants observed $0^{\circ}$, $18^{\circ}$, $36^{\circ}$, $54^{\circ}$, $72^{\circ}$, $90^{\circ}$, $108^{\circ}$, $126^{\circ}$, $144^{\circ}$, $162^{\circ}$, and $180^{\circ}$ coordination patterns characterized by two oscillating dots. The dots oscillated in 0.25 Hz for the pattern recognition training and in 0.5 Hz, 1 Hz, and 2 Hz for the pattern judgment test. Judgment score, absolute judgment error, and judgment stability out of the pattern judgment test were analyzed statistically. The landscape of pattern accuracy and stability data was "inverted-U" shape with slower oscillating frequency conditions. In the faster condition, the accuracy and stability of the judgment decreased with relative phase patterns near $180^{\circ}$. These findings consistent with the prediction of the HKB model. The grid as additional sensory information did not increase accuracy and stability in coordination perception.

• Korean Journal of Optics and Photonics
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• v.31 no.1
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• pp.31-36
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• 2020

We propose a band-switchable terahertz metamaterial based on an etched vanadium dioxide (VO₂) thin film. A line of etched VO₂ thin film was placed in the center gap of the split square-loop shape for the tunability of the metamaterial. The resonance frequency of the metamaterial can be switched from the 1.4 THz band to the 0.7 THz band, according to the insulator-metal phase transition in the VO₂ thin film. The absolute difference in the transmittance of the metamaterial was 78.5% and 65.8% at 0.7 THz and 1.4 THz respectively, according to the band switching. The differential phase shift was around 90°, and the transmittance was stably maintained between 40% and 60% in the middle band of the two switchable resonance-frequency bands.

• KLA journal
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• v.52 no.3
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• pp.26-32
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• 2011

문헌정보학 전공자에게 있어 취업의 꽃은 대학도서관 사서로의 진출이 아닐까 싶다. 왜냐하면 대학 도서관은 다른 관종의 도서관에 비해 외형적으로 규모가 크고, 업무는 다양할 뿐만 아니라 영역별로 전문화되어 있어 다양한 경험을 쌓을 수 있는 장점이 있다. 게다가 근무시간이나 급여, 복지 등과 같은 근무조건 및 환경 역시 타 관종에 비하여 비교적 우위에 있다고 하겠다. 때문에 전공자들 사이에는 기회가 된다면 누구나 대학도서관 사서로의 꿈을 꾸는 것이다. 하지만 최근 대학을 둘러싼 내외적인 상황이 그리 만만하지가 않다. 대학 외적으로는 대학 간 무한경쟁 체제의 확산 및 심화, 입학자원의 절대적 감소, 정부 및 각종 기관의 지원시 엄격한 평가 적용 등의 영향과 내적으로는 대학내 도서관 위상의 점진적 약화, 사서적인 수의 감소, 사서직에 대한 전통적 인식 약화로 인한 입지 위협 등으로 인하여 대하교직원 채용에 있어 도서관 사서는 대개 후순위이거나 고려대상에서 점점 더 멀어지고 있는 실정이다. 또한 최근에는 긍적적 측면과 부정적 측면이 상존하는 사서직원의 본부부서 이동 역시 늘어나고 있다고 하겠다. 한편 1987년 사서자격증 발급자가 2,000여명을 돌파한 이래 최근에는 매년 2,400여명 내외의 자격증 소지자를 배출하고 있는데, 본 글은 이 정도의 공급에 미루어 볼 때 전체 관종 대비 대학도서관 사서의 모집현황은 어느 정도인지? <사서e마을> 정규직, 비정규직 코너에 2007~2010년간 게재된 모집 공고 중심으로 월별, 지역별, 대학 설립주체별 현황 분석 및 전망을 해보고자 한다.

• Journal of the Korean Institute of Telematics and Electronics
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• v.12 no.6
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• pp.21-30
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• 1975

A method by which one can optimize the complex responses of electronic circuits has been suggested. represented in the complex forms, the optimization methods presented so far have dealt with real magnitude and phase responses of circuits. Design examples are shown on the optimal designs of an amplifier, filter, operational circuits transmission lines. and a wave-shaping circuit.

• Korean Journal of Optics and Photonics
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• v.7 no.1
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• pp.37-43
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• 1996

Two type interference air refractometers have been developed by using a frequency stabilized He-Ne laser in a transverse magnetic field. The refractometers were based on symmetric multiple pass interferometer. In this system, One part of the beams passed through air whose refractivity is to be measured and the other part of the beams passed through a vacuum champer to be used as a reference. Several measurements were performed under normal air condition. Maximum difference between two interference refractometers was ${\pm}2{\times}10^{-8}$.