• KIEE International Transactions on Power Engineering
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• 제5A권3호
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• pp.214-220
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• 2005

In order to improve energy efficiency and solve power disturbances, power components measurement for both the supply and demand side of a power system must be implemented before appropriate action on the power problems can be taken. This paper presents a DSP (Digital Signal Processor)-based multi-channel (voltage 8-channel and current 10-channel) power measurement system that can simultaneously measure and analyze power components for both supply and demand. Voltage 8-channel and current 10-channel measurement is made through voltage and current sensors connected to the developed system, and power components such as reactive power, power factor and harmonics are calculated and measured by the DSP. The measured data are stored in a personal computer (PC) and a commercial program is then used for measurement data analysis and display. After voltage and current measurement accuracy revision using YOKOGAWA 2558, the developed system was tested using a programmable ac power source. The test results showed the accuracy of the developed system to be about 0.3 percent. Also, a simultaneous measurement field test of the developed system was implemented by application to the supply and demand side of the three-phase power system.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 추계학술대회
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• pp.1540-1545
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• 2004

Measurement of concentration fields in a micro-channel is the crucial technology in the area of Lab-on-a-chip to be used for various bio-chemical applications. It is wel-known that the only possible way to measure the concentration field in the micro-channel is using micro-LIF(Laser Induced Fluorescence) method. However, an accurate concentration field at a given cross plane in a micro-channel has not been made so far due to the limit of light illumination. The present study demonstrates a novel method to provide an ultra thin laser sheet beam having 5 microns thickness by a micro focus laser line generator. Nile Blue A was used as fluorescent dye for LIF measurement. The laser sheet beam illuminates an exact plane of concentration measurement in the micro-channel to increase the signal to noise ratio and reduce the depth uncertainty considerably.

• 대한전기학회논문지:시스템및제어부문D
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• 제54권1호
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• pp.56-60
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• 2005

In the power-line communication(PLC) systems, the power line is a wired medium. However, the power line channel has the multi-path fading characteristics like the wireless channel in the wireless communication systems because it has the signal reflection and divergence by the impedance mismatching between many branch lines and loads. So the analysis of the multi-path characteristics is very important, and it has been doing by the several measurement methods for the impulse response between the transmitter and the receiver. PN sequence method has originally been used as a wideband impulse response measurement mettled for wireless channel, but it is recently being applied to not only the wireless channel but also the wired channel like the power line channel. This method is more useful and effective for the long distance communication channel like the medium voltage power distribution line with the multi-paths[1]. In this thesis, we have measured impulse response for the medium voltage power distribution line channel by the wideband measurement method using PN sequence, analytically studied the measured data and presented the results.

• 방사선산업학회지
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• 제6권3호
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• pp.231-237
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• 2012

This paper introduces a gamma-ray measurement system for a transportable tomography which is applicable for an industrial process diagnosis. The gamma-ray measurement system consists of pulse mode operating 72 channel CsI detectors, main AMP-pulse shaper, single channel analyzer, counter and control PC. The CsI crystal is coupled with a PIN diode which is connected to an amplifier and pulse shaper. For a compact design, the amplifier and pulse shaping circuit are included in a single package. 36 sets of CsI detectors are connected to a multi-channel counter through single channel analyzers. A computer controls and collects data from two multi-channel counters. This configuration results in 72 channel counting system in total. The CT rotator and radiation measurement system are controlled by a PC with LabVIEW program. Tomographic data were measured for a phantom by the measurement system and transportable gamma-ray CT. From the experimental data image reconstructions were performed by ML-EM algorithm. The result showed that the CsI detector system can be a suitable component for transportable gamma-ray CT system.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 하계학술대회 논문집 D
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• pp.2640-2642
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• 2002

In this paper, we show the channel characteristics measurement system the frequency range up to 30MHz for medium voltage Power Line Grid. Power line channel characteristics are investigated by means of various measurement instruments. Measurement system consists of medium voltage coupler, impedance measurement part, noise measurement part, voltage sensing part and communication part. Measured data will be used for PLC channel modeling and PLC network system design.

• 전력전자학회논문지
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• 제11권3호
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• pp.233-238
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• 2006

전력 외란을 해결하기 위해서는 전력 계통의 전원 측과 부하 측 양단에서 전력 성분의 측정이 요구된다. 본 논문은 전원 측과 부하 측 양단에서 동시에 전력 성분을 측정하고 분석할 수 있는 DSP(디지털 신호 처리 장치) 기반의 다채널(전압 8채널, 전류 10채널) 전력 성분 측정 시스템을 제안하였다. 개발된 시스템은 YOKOGAWA 2558을 이용하여 전압과 전류를 보정한 후, 전력 계통 현장에서 실험하였다.

• 한국항해항만학회지
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• 제32권2호
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• pp.141-148
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• 2008

This paper is structured into three main parts and a conclusion. The main section provide definitions of efficiency, effectiveness and performance in terms of the distribution channel, followed by a review of related performance measurement, before discussing difficulties of measurement. According to the theoretical approach, it appears that key theroretical issues are centered around customer service, logistics excellence, time compression, the use of IT, and a move towards integrated logistics. The empirical approach shows that in the past, various financial performance indicators were regarded as relevant management information. However, today, management needs additional performance indicators. Therefore, external assessments of effectiveness must be performed to measure customers' satisfaction with the physical flow of product through the distribution channel network. So, what is needed is to take previous normative and explorative research and progress through a framework by developing valid measures of distribution channel's effectiveness and efficiency, and identifying research methodologies suited to the data collection requirements.

• 전자공학회논문지A
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• 제29A권7호
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• pp.56-63
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• 1992

A measurement technique of the surface generation velocity S$_o$ using the BC(buried channel) MOS structure with shallow and low doped channel layer (BC MOS S$_o$ measurement technique) is presented and verified analytically and experimentally. Using this measurement technique, S$_o$ can be measured more accurately than that measured using the gate-controlled diode SS1oT measurement technique. When S$_o$ is measured for the two techniques from a BC MOS structure test patten with gate length of 171$\mu$m, the results are 0,66cm/sec and 0.28cm/sec for the former and the latter respectively.

• 한국통신학회논문지
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• 제30권2A호
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• pp.51-60
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• 2005

본 논문에서는 WCDMA(Wideband Code Division Multiple Access) 단말 모뎀을 위한 개선된 SIR 측정 알고리즘을 제안한다. 제안된 알고리즘은 속도 적응형 IIR 타입의 channel estimator를 적용함으로써 DPCH(Dedicated Physical Channel)의 채널 보상으로 인한 처리 지연을 최소화하였으며, 파일럿 채널인 CPICH(Common Pilot Channel)를 사용하여 페이딩 채널 환경에서 발생하는 신호 전력 감쇄를 보상함으로써 페이딩 환경에서 SIR 측정시 발생하는 SIR 측정 오차를 대폭 감소시켰다. 또한 fading의 변화를 적절히 반영할 수 있도록 IIR 필터를 신호 전력 및 간섭 전력 측정 시에 추가함으로써 SIR 측정에 대한 안정도를 향상시켰다. 제안된 알고리즘과 기존의 SIR 측정 알고리즘과의 성능 비교를 통하여 무선 이동 채널, 특히 고속 이동체 환경에서 제안된 알고리즘의 측정된 SIR의 mean은 최대 약 8dB, jitter는 약 2dB의 향상된 우수한 성능을 보임을 입증하였다.

• 한국통신학회논문지
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• 제37권4A호
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• pp.205-213
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• 2012

본 논문에서는 IEEE 802.11 무선 네트워크에서 재밍 (jamming) 공격에 효과적으로 대처할 수 있는 IEEE 802.11h 기반의 채널 도약 기법을 제안한다. IEEE 802.11h의 Dynamic Frequency Selection (DFS)은 현재 사용하는 채널에서 군 레이더와 같은 높은 간섭을 감지할 경우 임의의 채널을 선택하지 않고 전체 채널 측정을 통해 가장 좋은 채널로 도약하는 기법이다. 이러한 기법은 재밍 공격이 발생하는 환경에서는 채널 도약을 위해 모든 채널 측정을 위한 시간이 소요되며 그 시간만큼의 통신 단절이 발생해 네트워크 성능이 저하되는 단점을 가진다. 제안하는 기법에서는 기존의 기법과는 달리 재밍 공격 이전에 도약할 채널을 모든 단말이 알게 함으로써 재머에 대해 즉각적인 대처가 가능하다. 이를 위해 제안하는 기법에서는 비콘 (Beacon)을 통해 도약할 채널을 매번 갱신하며 이것은 이전 비콘 구간마다 전채널 상태 측정을 수행하는 것으로 가능하다. 다양한 환경에서의 모의 실험을 통해 제안 기법이 재머에 즉각적인 대응을 수행함으로써 네트워크 성능 저하를 완화할 수 있음을 확인할 수 있다.