• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2000년도 추계학술대회논문집
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• pp.330-335
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• 2000

This paper deals with sensing ability of smart sensor that has a sensing ability of distinguish materials. We have developed new signal processing method that have distinguish different materials. We made the two type of smart sensors for experiment. The first type of smart sensor is H2 type. The second type of smart sensor is HH type. The smart sensor was developed for recognition of material. And then we developed estimation method of sensing ability of smart sensors. The first method(Sensing Ability Index) is developed for H2 smart sensor. The second method($R_{SAI}$ Index) is developed for HH smart sensor. We estimated sensing ability of smart sensor with new SAI and $R_{SAI}$ method. This paper describes our primary study for a new method of estimate sensing ability of smart sensor, which is need for precision work system. This is a study of dynamic characteristics of smart sensor according to frequency and displacement changing with new SAI and $R_{SAI}$ method. Experiment and analysis are executed for proper dynamic sensing condition. First, we developed advanced smart sensors. Second, we develop new SAI and $R_{SAI}$ methods that have a sensing ability of distinguish materials. Dynamic characteristics of smart sensor are evaluated through new SAI and $R_{SAI}$ method relatively. We can use the new SAI and $R_{SAI}$ method for finding materials. Applications of this method are finding abnormal condition of object(auto-manufacturing), feeling of object(medical product), robotics, safety diagnosis of structure, etc.

• Korean Journal of Geomatics
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• 제2권1호
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• pp.57-64
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• 2002

Measuring the depth of water is very important in ensuring the protection and safety of seaside. There are many difficulties in making the contour bathymetric map, and contour line due to the limitation of continuous measurement of water depth and collimation with the conventional measuring and positioning methods. But the real-time kinematic GPS (RTK GPS) positioning using a carrier phase enables us to decide a precise position without breaking a signal even under the condition of a moving environment. It is also possible to obtain an accurate depth of water in real time with a fathometer through the measuring of time delay between sending and receiving epochs. This research aims at investigation of accuracy potential of RTK GPS in combination with Echo Sounder(E/S) for the coastal mapping. Apart from this purpose, the accuracy of ambiguity resolution with the OTF(On the Fly) method was tested with respect to the initialization time. The result shows that the accuracy is better than 1cm with 5-minute initialization in the distance of 10km baseline. The seaside topography was measured by the RTK GPS only, on the other hand the seafloor topography was surveyed in combination of RTK GPS and E/S. Comparing to the volume of seaside measured by RTK GPS and digital topographical map, the difference of only 2 % was achieved. This indicates that the coastal mapping with RTK GPS is successfully conducted. In addition it is also demonstrated that the 3-dimensional perspective model resulted from the undersea topography measured by RTK GPS and E/S is very close to that from the digital map. Through this study, it was verified that RTK GPS is to be very useful method in the analysis of coastal morphology owing to its capability of getting the precise DTM for the using of harbor reclamation, dredging, and the estimation of soil movement in a river.

• 한국화재소방학회논문지
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• 제32권3호
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• pp.95-107
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• 2018

화재조사 결과를 토대로 고양종합터미널 건물 화재 시 소방시설 작동 실태를 분석하였다. 분석결과를 요약하면 다음과 같다. 첫째, 천장 우레탄폼에 불이 붙은 직후에 옥내소화전을 이용하여 진화할 수 있음에도 시도하지 않았다. 둘째, 지하1층 대수선공사 공간은 스프링클러 알람밸브를 잠가놓아 작동하지 않았지만, 지하2층과 지상1층, 지상2층, 지상3층은 스프링클러가 작동하여 지하1층 대수선공사 공간 이외의 층으로의 화재확산을 저지하였다. 셋째, 피난유도등은 정상 작동하였지만, 터미널 2층 대합실에서 승차장 쪽으로 통하는 출구(비상구)에 피난구유도등이 설치되어 있지 않아 터미널 2층에서 다수의 사상자가 발생하게 하는데 영향을 미쳤다. 넷째, 화재수신기에서 제연설비 배기 팬 제어반에 전기신호를 보냈지만 배기 팬의 제어반에서 수동으로 취급하여 터미널 2층 제연설비 배기 팬이 작동하지 않았다.

• 한국산학기술학회논문지
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• 제12권9호
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• pp.4112-4118
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• 2011

전기철도는 전차선을 통해 차량을 구동할 수 있는 전력을 공급하며, 공급된 전류는 선로 및 접지망을 통해 변전소로 귀환한다. 귀선전류는 신호, 전력, 전차선 및 궤도시스템과 연관되며, 선로변 직원의 안전과 전철화에 따른 철도관련 전기시스템의 보호를 위해 취급되어야 할 가장 중요한 요소 중 하나이다. 따라서 귀선전류의 불평형 및 과전류 상태에 의한 시스템유도장해, 고장을 막기 위해서는 귀선전류의 정확한 분석이 필요하다. 본 논문은 귀선전류의 불평형 및 과전류 상태에 의한 시스템 유도장해, 고장을 예방하기 위해 실제 현장에서 측정 및 분석방법을 제시하였으며 또한 시험기준에 의한 안전성을 평가하였다. 이러한 결과는 향후 이와 관련된 분야에 크게 기여할 것으로 기대된다.

• 한국산학기술학회논문지
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• 제15권5호
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• pp.3100-3106
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• 2014

본 논문에서는 전력 시스템의 전원 및 부하 측을 동시에 감시가 가능한 다 채널(전압 8채널, 전류 10채널) 전력 측정 시스템을 개발하였다. 제안된 시스템은 전력품질과 관련된 규정인 IEEE 1459-2010의 정의를 사용하여 전력 성분을 계산하는 신호처리 알고리즘을 기반으로 TMS320C42 DSP를 이용하여 개발하였다. 개발된 시스템은 표준 전원 공급 장치를 이용하여 그 성능 시험을 실시하였고, 그 결과 측정오차는 0.2% 이하로 나타났다. 또한 제안된 시스템을 3상 4선식 전력시스템에 설치하여 실증 시험을 실시하여 그 성능을 입증하였다. 제안된 시스템은 상업 및 산업용 전력 시스템에 적용하여 동시에 다 채널로 전력을 측정 및 분석함으로써 전력품질과 관련된 다양한 문제를 줄일 수 있을 것이다.

• 스마트미디어저널
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• 제7권3호
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• pp.64-71
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• 2018

무인항공기의 활용분야가 국방, 산업, 엔터테인먼트 그리고 개인의 취미영역까지 여러 분야로 급속히 확대되고 있다. 다수의 무인항공기 운영으로 인해, 목적지 이외의 지역으로 비행경로 오류가 발생하고, 적대적 국가의 무인항공기 탈취로 인한 안보 위협과 불법 영상촬영에 따른 개인정보 노출로 인한 2차 피해까지 보안의 여러 문제점이 증가되고 있다. 본 논문은 이러한 보안 이슈에 대해, GPS 스푸핑, 촬영한 영상정보 다운로드 해킹, 전파 재밍을 통한 신호 감쇄로 오작동, 영상 촬영 자료로 인한 개인정보 노출 등 보안 취약점을 발견하였다. 이를 해결하기 위해, GPS 스푸핑 공격 방지, VPN(Virture Private Network)을 활용한 영상촬영 정보 구간의 암호화를 설정하여 비정형 데이터의 안정성을 확보하였다. 또한, 무인항공기 촬영 개인정보 노출에 따른 2차 피해를 최소화하고 안전성을 확보하기 위한 방안으로 개인정보 암호화와 마스킹 기법을 적용하여, 데이터의 무결성을 확보 하였다. 점차 증가되는 무인항공기의 응용분야에서 안전한 사용과 산업 활성화에도 기여 할 것으로 기대한다.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2009년도 추계학술대회
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• pp.545-548
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• 2009

최근 운전자의 건강상태 모니터링 및 졸음운전 방지를 위한 자동차용 부품관련 센서개발 및 시스템 연구들이 국내외에서 활발히 진행되고 있다. 본 논문은 이러한 운전자의 건강상태 및 졸음운전을 점검하기 위해 체스트벨트(ECG)와 손목착용형 산소포화도($SpO_2$) 센서를 제작하여 생체신호를 측정하였으며, 측정된 심전도, 산소포화도, 그리고 심장박동수 신호는 센서네트워크를 통해 수집, 전송 및 모니터링 등의 처리를 가능하게 하여 운전자에게 안전운행을 위한 정보를 제공하도록 하였다. 원격지인 서버 PC와 연결된 베이스스테이션으로 수집된 심전도와 용적맥파 신호에서 HRV(Heart Rate Variability, 심박변이도) 신호를 검출하였으며, 검출된 HRV 신호를 시간 영역과 주파수 영역에서의 해석을 통하여 운전자의 스트레스 지수 및 졸음 상태의 실시간 모니터링 및 졸음 상태의 운전자에게 주의를 제공하기 위하여 알람을 제공하는 형태의 지능형 모니터링 시스템을 구현하였다.

• Smart Structures and Systems
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• 제15권1호
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• pp.135-150
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• 2015

Large concrete structures are prone to cracks and damages over time from human usage, weathers, and other environmental attacks such as flood, earthquakes, and hurricanes. The health of the concrete structures should be monitored regularly to ensure safety. A reliable method of real time communications can facilitate more frequent structural health monitoring (SHM) updates from hard to reach positions, enabling crack detections of embedded concrete structures as they occur to avoid catastrophic failures. By implementing an unconventional mode of communication that utilizes guided stress waves traveling along the concrete structure itself, we may be able to free structural health monitoring from costly (re-)installation of communication wires. In stress-wave communications, piezoelectric transducers can act as actuators and sensors to send and receive modulated signals carrying concrete status information. The new generation of lead zirconate titanate (PZT) based smart aggregates cause multipath propagation in the homogeneous concrete channel, which presents both an opportunity and a challenge for multiple sensors communication. We propose a time reversal based pulse position modulation (TR-PPM) communication for stress wave communication within the concrete structure to combat multipath channel dispersion. Experimental results demonstrate successful transmission and recovery of TR-PPM using stress waves. Compared with PPM, we can achieve higher data rate and longer link distance via TR-PPM. Furthermore, TR-PPM remains effective under low signal-to-noise (SNR) ratio. This work also lays the foundation for implementing multiple-input multiple-output (MIMO) stress wave communication networks in concrete channels.

• Smart Structures and Systems
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• 제6권5_6호
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• pp.749-765
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• 2010

There are on-going efforts to utilize guided waves for structural damage detection. Active sensing devices such as lead zirconate titanate (PZT) have been widely used for guided wave generation and sensing. In addition, there has been increasing interest in adopting wireless sensing to structural health monitoring (SHM) applications. One of major challenges in wireless SHM is to secure power necessary to operate the wireless sensors. However, because active sensing devices demand relatively high electric power compared to conventional passive sensors such as accelerometers and strain gauges, existing battery technologies may not be suitable for long-term operation of the active sensing devices. To tackle this problem, a new wireless power transmission paradigm has been developed in this study. The proposed technique wirelessly transmits power necessary for PZT-based guided wave generation using laser and optoelectronic devices. First, a desired waveform is generated and the intensity of the laser source is modulated accordingly using an electro-optic modulator (EOM). Next, the modulated laser is wirelessly transmitted to a photodiode connected to a PZT. Then, the photodiode converts the transmitted light into an electric signal and excites the PZT to generate guided waves on the structure where the PZT is attached to. Finally, the corresponding response from the sensing PZT is measured. The feasibility of the proposed method for wireless guided wave generation has been experimentally demonstrated.

• Smart Structures and Systems
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• 제6권5_6호
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• pp.641-659
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• 2010

Structural Health Monitoring (SHM) gradually becomes a technique for ensuring the health and safety of civil infrastructures and is also an important approach for the research of the damage accumulation and disaster evolving characteristics of civil infrastructures. It is attracting prodigious research interests and the active development interests of scientists and engineers because a great number of civil infrastructures are planned and built every year in mainland China. In a SHM system the sheer number of accompanying wires, fiber optic cables, and other physical transmission medium is usually prohibitive, particularly for such structures as offshore platforms and long-span structures. Fortunately, with recent advances in technologies in sensing, wireless communication, and micro electro mechanical systems (MEMS), wireless sensor technique has been developing rapidly and is being used gradually in the SHM of civil engineering structures. In this paper, some recent advances in the research, development, and implementation of wireless sensors for the SHM of civil infrastructures in mainland China, especially in Dalian University of Technology (DUT) and Harbin Institute of Technology (HIT), are introduced. Firstly, a kind of wireless digital acceleration sensors for structural global monitoring is designed and validated in an offshore structure model. Secondly, wireless inclination sensor systems based on Frequency-hopping techniques are developed and applied successfully to swing monitoring of large-scale hook structures. Thirdly, wireless acquisition systems integrating with different sensing materials, such as Polyvinylidene Fluoride(PVDF), strain gauge, piezoresistive stress/strain sensors fabricated by using the nickel powder-filled cement-based composite, are proposed for structural local monitoring, and validating the characteristics of the above materials. Finally, solutions to the key problem of finite energy for wireless sensors networks are discussed, with future works also being introduced, for example, the wireless sensor networks powered by corrosion signal for corrosion monitoring and rapid diagnosis for large structures.