• 대한전기학회:학술대회논문집
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• 대한전기학회 2007년도 제38회 하계학술대회
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• pp.598-599
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• 2007

The electricity supply industry for which high stability and quality of power are the primary aim of power company and the first order of business target. As the facilities of generations, transmissions and substations are increased every year, power system becomes more complex and hard to control. The complexity of the power system causes harmful influence on its security and power facilities. Moreover, difficulty of predicting weather condition in these days with its complexity increases the level of uncertainty of energy demand. Wide area online monitoring of power system offers lots of informations and solutions which clear the causes of insecurity in power system. In this paper, we presents the development of synchrophasor data measurement and transmission system using satellite network for power system online monitoring.

• 전기학회논문지P
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• 제57권4호
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• pp.424-430
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• 2008

A new active vibration measurement system in electric power transmission line is presented, using in the nondestructive test. With a permanent magnet and a couple of coils, the system exerts impact force to a test object and in turn picks up the vibration of the object. The natural frequency with the amplitude obtained from the system are used as a basis for the detection of defects in the object. The system is controlled by an electronic device designed to facilitate the fully automated testing process with consistent repeatability and reliability which are essential to the nondestructive test. The system is expected to be applied to the wide area of defect detection including the classification of mechanical parts in production and inspection processes.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2008년도 제39회 하계학술대회
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• pp.2023-2024
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• 2008

근래 초기고장(seed fault)에 대한 적절치 못한 대책들이 광역정전으로 파급되어 그 피해정도가 매우 심각하다. 전력의 안정적 공급에 대한 중요성이 새롭게 부각되고 그 예방책에 대한 다각적인 연구가 요구되고 있다. 이에 위성망을 이용한 위기 관리시스템에 대한 필요성이 제기되었다. 본 논문에서는 광역보호를 위해 sPMU(satellite Phasor Measurement Unit), 전력계통 상태감시장치(Power System Dynamic Monitor:PSDM)에 중요한 요소로서 전력계통에서 가장 중요한 지표중의 하나인 주파수에 대한 여러 가지 측정방법을 다룬다. 향후 정상상태와 과도상태에서도 측정시간 단축과 측정오차를 줄일 수 있는 최적의 주파수 계측기법을 개발하기 위함이다.

• 한국농업기계학회:학술대회논문집
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• 한국농업기계학회 2017년도 춘계공동학술대회
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• pp.122-122
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• 2017

Recently, environmental problems have become an area of growing interests. In-situ monitoring of water quality is fundamental to most environmental applications. The accurate measurement of nitrate concentrations is fundamental to understanding biogeochemistry in aquatic ecosystems. Several studies have reported that one of the most feasible methods to measure nitrate concentration is the use of Ion Selective-electrodes (ISEs). The ISE application to water monitoring has several advantages, such as direct measurement methodology, high sensitivity, wide measurement range, low cost, and portability. However, the ISE methods may yield inconsistent results where there was a difference in temperature between the calibration and measurement solutions, which is associated with the temperature dependence of ionic activity coefficients in solution. In this study, to investigate the potential of using the combination of a temperature sensor and nitrate ISEs for minimizing the effect of temperature on real-time nitrate sensing in natural water, a prototype of on-site water monitoring system was built, mainly consisting of a sensor chamber, an array of 3 ISEs, an waterproof temperature sensor, an automatic sampling system, and an arduino MCU board. The analog signals of ISEs were obtained using the second-order Sallen-key filter for performing voltage following, differential amplification, and low pass filtering. The performance test of the developed water nitrate sensing system was conducted in a monitoring station of drinking water located in Jeongseon, Kangwon. A temperature compensation method based on two-point normalization was proposed, which incorporated the determination of temperature coefficient values using regression equations relating solution temperature and electrode signal determined in our previous studies.

• Smart Structures and Systems
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• 제4권2호
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• pp.183-194
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• 2008

An important historical monument of Cyprus is an aqueduct that was built in 1747 to provide water to the city of Larnaca and to its port. Because of its importance to the cultural heritage of Cyprus, the aqueduct has been selected as one of the case-study monuments in the project Wide-Range Non-Intrusive devices toward Conservation of Historical Monuments in the Mediterranean Area (WIND-CHIME). Detailed drawings of the aqueduct obtained from the Department of Antiquities of Cyprus have been used for the development of a computational model. The model was fine-tuned through the measurement of the dynamic characteristics of the aqueduct using forced and ambient vibrations. It should be noted that measurement of the dynamic characteristics of the structure were performed twice in a period of three years (June of 2004 and May of 2007). Significant differences were noted and they are attributed to soil structure interaction effects due to seasonal variations of the water-level in a nearby salt-lake. The system identification results for both cases are presented here. This monument was used to test the effectiveness of shape memory alloy (SMA) pre-stressed devices, which were developed during the course of the project, in protecting it without spoiling its monumental value.

• 전기학회논문지P
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• 제63권1호
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• pp.1-6
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• 2014

An electric power system sometimes fails because of disturbances that occur unexpectedly, such as the uncontrolled loss of load that developed from cascading blackout. Which make stability through a little of under voltage load shedding should work. The development of phasor measurement unit(PMU) makes network supervision possible. The information obtained from PMU is synchronized by global positioning system(GPS). There are many real-time algorithms which are monitoring the voltage stability. This paper presents the study on the VILS(Voltage Instability Load Shedding) using PMU data. This algorithm computes Voltage Stability Margin Index(VSMI) continuously to track the voltage stability margin at local bus level. The VSMI is expressed as active and reactive power. The VSMI is used as an criterion for load shedding. In order to examine the algorithm is effective, applied to KEPCO system.

• 한국산학기술학회논문지
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• 제14권1호
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• pp.385-392
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• 2013

안개로 인한 대형교통사고를 예방하기 위한 안개경고시스템의 핵심요소는 시정을 측정하는 장치이며, 최근 고가의 안개센서 보다 인간의 시정감각과 유사하면서도 저렴하고 정확한 시정측정장치에 대한 필요성이 증대되고 있다. 본 논문은 도로의 CCTV 카메라를 이용하여 시정을 측정하기 위해 개발된 도로시정측정시스템(RVMS)의 성능 평가 방법 및 결과를 제시하고, 고속도로 등 도로 적용에 따른 경제성과 활용방안을 제시한다. 성능평가는 여주시험도로에 전용 CCTV 카메라, 안개센서, 목측을 위한 시정표지를 설치하고 시험운영결과를 DVR에 기록하여, 특정 안개발생 시간대에 대해 RVMS와 안개센서 결과를 목측결과와 비교분석하였다. 실험결과, 목측을 기준으로 RVMS가 안개센서 대비 높은 측정안정성과 정확성을 가진 것으로 분석되었다. 또한, 본 논문에서는 RVMS가 기존 안개센서 대비 높은 경제성을 가지고 있음을 제시하고 RVMS의 다양한 활용방안을 제시한다. 높은 성능과 경제성을 가진 RVMS의 적절한 활용은 안개발생시 도로 이용자의 교통사고 예방뿐만 아니라 광역 시정정보 수집 및 활용에 획기적인 계기를 마련할 것으로 기대된다.

• 터널과지하공간
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• 제19권1호
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• pp.31-42
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• 2009

수렴다중촬영기법을 응용하여 개발된 가이드포인트법(GP법)의 측정 시스템을 개발하였다. GP법은 사진측량기법의 하나로 본 연구에서는 암반 사면에 노출된 절리의 방향성을 측정하기 위하여 개발된 시스템을 적용하였다. 개발된 기법의 현장 적용에 앞서 오차 수준과 촬영영향요소 분석을 위해 실내검증시험 및 최적촬영배열 설계가 이루어졌다. 실내 검증 결과 적정 수렴각은 $25^{\circ}{\sim}150^{\circ}$로 나타났으며, 2M 화소의 디지털 사진기를 사용할 경우 측정 오차 한계를 만족하는 최적 촬영거리는 약 5.5 m이었다. 현장 석용에서는 GP법의 효용성을 극대화하기 위하여 본 연구에서 개발된 확장해석 기법이 적용되었다. 확장해석기법은 넓은 지역에 대한사진측량 조사를 실시할 경우 적용할 수 있는 것으로 최초 촬영면에서 측정된 특정 점들의 좌표를 인접한 다음 촬영면에서 조절점으로 사용함으로써 현장에서의 촬영 시간을 단축시킬 수 있는 방법이다.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2010년도 하계학술대회 논문집
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• pp.9-10
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• 2010

The lighting control power circuits should be designed in stable region according to the environment. A stable circuit is analyzed using ac equivalent circuits. The flyback converter with wide input voltage ranges is suitable for lighting control system. It is designed optimally for stability. The specifications are that the input voltage is 90V-230V, the output power is 12V/2.5A. The stability analysis is established using PSM(Phase Sensitive Multimeter) in experiment. As a result, it is confirmed that the gain margin and the phase margin are in stable area. The validity of the experimental measurement is verified.

• 한국전자파학회논문지
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• 제17권9호
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• pp.804-810
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• 2006

본 논문은 후방 산란 계수 및 지표면 특성(ground truth)에 대한 측정 방법을 기술하며 후방 산란 계수 측정값과 radiative transfer 이론을 적용하여 개발된 산란 모델을 비교함으로써 산란 모델의 정확성을 검증한다. R 밴드 $(1.7\sim2.0GHz)$의 주파수 대역에서 polarimetric scatterometer 시스템으로 한강생태공원의 수풀 지형에서의 후방 산란 계수를 입사 각도의 변화와 지표면 수분 함유량의 변화에 따라 측정한다. 이 측정 결과를 지표 산란 모델과 비교한 결과 동일 편파의 경우 비교적 잘 일치하며 교차 편파의 경우 보정을 해줌으로써 산란 모델의 정확성을 얻을 수 있다.