다중화된 광섬유 BG 센서에 의한 변형률의 측정

권일범,김치엽,윤동진,이승석 한국비파괴검사학회 2003 학술대회 논문집 Vol.- No.1

FBG(Fiber Bragg grating) sensor, which is one of the fiber optic sensors for the application of smart structures, can not only measure one specific point but also multiple points by multiplexing techniques. We have proposed a novel multiplexing technique of FBG sensor by the intensity modulation of light source. This technique is applicable to WDM(Wavelength Division Multiplexing) technique and number of sensors in this system can be increased by using this technique with WDM technique

광섬유 산란형 센서를 이용한 사회기반시설물의 보안에 관한 연구

권일범,윤동진,이승석 한국비파괴검사학회 2004 한국비파괴검사학회지 Vol.24 No.5

광섬유 ROTDR (Rayleigh optical time domain reflectometry) 센서와 보다 긴 광섬유를 감지광섬유로 사용할 수 있는 광섬유 BOTDA (Brillouin optical time domain analysis) 센서를 구성하고, 이들 각각을 이용하여 중요보안 대상체인 사회기반시설물에 침투하는 침입자를 탐지할 수 있는 기초 연구를 수행하였다. ROTDR 센서의 감지부로는 넓은 면적을 감지할 수 있는 매설형 광섬유 센서 탐지판을 제작하고, 인가된 침입물체의 위치와 무게에 따른신호특성을 고찰하였다. ROTDR 센서는 펄스 폭이 30 ns이고, 광섬유의 길이는 10 km 이상이다. 위치탐지오차는 약 2m 이내였으며, 무게에 따른 탐지능력은 20 kgf, 40 kgf, 60 kgf, 80 kgf의 네 단계를 구분할 수 있음을 알 수 있었다. 넓은 지역에 걸친 침입자의 침투를 감시하기 위하여 수십 km의 광섬유 길이 전체를 감지부로 사용할 수 있는 광섬유 BOTDA 센서를 개발하였다. BOTDA 센서는 한 개의 레이저 다이오드와 두 개의 광전 변조기(electro-optic modulator)를 사용하여 간단하게 구성하였다. 침입자에 의한 광섬유의 변형률 벽화를 탐지하는 실험을 수행하기 위하여 광학테이블 위에 광섬유에 변형률을 인가하기 위한 실험 장치를 설치하여 실험을 수행하였다. 이 실험으로부터 시간간격 1.5 초동안 광섬유 약 4.81 km의 길이를 거리분해능 3 m로 침입자를 탐지할 수 있음을 확인하였다. We have studied the detection techniques, which can determine the location and the weight of an intruder into infrastructure, by using fiber-optic ROTDR (Rayleigh optical time domain reflectometry) sensor and fiber-optic BOTDA (Brillouin Optical time domain analysis) sensor, which can use an optical fiber longer than that of ROTDR sensor. Fiber-optic sensing plates of ROTDR sensor, which are buried in sand, were prepared to respond the intruder effects. The signal of ROTDR was analyzed to confirm the detection performance. The constructed ROTDR could be used up to 10 km at the pulse width of 30 ns. The location error was less than 2 n1 and the weight could be detected as 4 grades, such as 20 kgf, 40 kgf, 60 kgf and 80 kgf. Also, fiber optic BOTDA sensor was developed to be able to detect intrusion effect through an optical fiber of tens of kilometers longer than ROTDR sensor. Fiber-optic BOTDA sensor was constructed with 1 laser diode and 2 electro-optic modulators. The intrusion detection experiment was peformed by the strain inducing set-up installed on an optical table to simulate a11 intrusion effect. I11 the result of this experiment, the intrusion effect was well detected as the distance resolution of 3 m through the fiber length of about 4.81 km during 1.5 seconds.

구조물의 변형률 측정을 위한 3x3 광섬유 마이켈슨 센서의 신호처리

권일범,문한규 경북대학교 센서기술연구소 1997 센서技術學術大會論文集 Vol.8 No.1

The measuring method of structural strain by a passive-demodulated fiber optic interferometric sensor was developed to implement the real-time monitoring of structural status. A 3x3 fiber optic Michelson interferometric sensor was constructed to sense the value and the direction of structural strain. This sensor was applied on the cantilevered aluminum beam to experiment the sensing of the structural deformation. The digital signal processing was programmed by LabVIEW to determine the structural strain from the fiber optic signals. This program was verified by various simulated fiber optic signals.

AISI 316 스테인리스강의 크리프-피로 상호작용시 수명예측에 관한 연구

권영일,김범준,임병수 成均館大學校 科學技術硏究所 2000 論文集 Vol.51 No.2

The effect of tensile hold time on the creep-fatigue interaction in AISI 316 stainless steel was investigated. To study the fatigue characteristics of the material, strain controlled low cycle fatigue(LCF) tests were carried out under the continuous triangular waveshape with three different total strain ranges of 1.0%, 1.5%, and 2.0%. To study the creep-fatigue interaction, 5 min., 10 min., and 30 min. of tensile hold times were applied to the continuous triangular waveshape with the same three total strain ranges. The creep-fatigue life was found to be the longest when the 5 min. tensile hold time was applied and was the shortest when the 30 min. tensile hold time was applied. The cause for the shortest creep-fatigue life under the 30 min. tensile hold time is believed to be the effect of the increased creep damage per cycle as the hold time increases. Under the total strain range of 1%, significant reduction in life was observed as the tensile hold time was increased compared to the result of 2% total strain range. The theoretical prediction obtained by the Modified Coffin-Manson method and the experimental results of creep-fatigue life were found to be in resonable agreement with each other.

유지시간 변화에 따른 크리프-피로 수명예측 방법에 관한 연구

권영일,김범준,임병수 成均館大學校 科學技術硏究所 2001 論文集 Vol.52 No.2

In this study, creep-fatigue tests were carried out under the various test conditions using AISI 316 stainless steel. Life prediction was made by three different methods which are the modified Coffin-Manson method, the modified Ostergen method and the artificial neural network method with the adaptive learning rate. The predicted lives were compared with the experimental results and following conclusions were obtained within the scope of this study. Creep-fatigue life prediction by the modified Coffin-Manson method and the modified Ostegren method had the average error of 47.3% and 50.8% respectively whereas the artificial neural network method had only 28.8% for compressive and tensile+compressive hold time. From the obtained results, the artificial neural network method with the adaptive learning rate was proved to be more accurate and effective than the other two methods. The validity of artificial neural network method for life prediction checked with 3 verification data points proved also to be very satisfactory.

무선 다점 온도센서에 의한 빌딩의 화재 탐지

김치엽,권일범 한국비파괴검사학회 2004 한국비파괴검사학회지 Vol.24 No.5

현대의 대형 건물은 복잡한 전기 배선 또는 가스 배관 등의 설비를 갖추고 있어서 다양한 화재 사고가 발생할 가능성이 커졌다. 이에 따라 무선의 다점 온도 측정 센서를 손쉽게 여리 위치에 설치 가능하도록 저렴하게 개발하여 적용함에 의하여 화재를 조기에 탐지하고 그 피해의 크기를 최소화하는 것이 필요하다. 무선 온도 센서의 송신기는 4채널로 9600 bps의 전송속도와, 10 mW의 출력으로 915 MHz 통신 주파수를 갖고 수신기와 작동되도록 구성하였다. 온도범위 -55 ~ 150도 사이에서 사용할 수 있도록 검증된 반도체 온도 센서 소자를 기본으로 사용하여 4개의 채널을 구성하고 실험을 수행한 곁과 개발된 센서 시스템이 화재 탐지용으로 적용이 가능함을 확인하였다. Fire accidents often happen in large buildings because large buildings are equipped with heavy electrical wiring and piping. When fire is to be occurred in those buildings, it is very dangerous to people and building structures. Therefore, multi-point wireless temperature sensors for large buildings arc necessary in order to detect fire in the early time and thus to minimize the loss. A wireless device was composed of the transmitter and receiver. The specification of this device was as follows: 915 MHz of transmitted frequency, 4 channels, 9600bps of the transmitted speed, and 10 mW of the transmitted power. We confirmed through experiment that the temperature was well sensed and fire location was determined by the 4 channel sensors of the developed sensor system.

광섬유 ROTDR 센서를 이용한 침입 탐지기법의 개발

백세종,권일범,정철,유재왕 한국센서학회 2002 센서학회지 Vol.11 No.4

광섬유 ROTDR (Rayleigh Optical Time Domain Reflectometry )을 이용하여 침입자를 높은 감도와 넓은 영역에서 탐지할 수 있는 매설형 광섬유 센서의 개발에 관한 실험을 수행하였다. 단위 길이당 넓은 면적을 감지 할 수 있는 매설형 광섬유 감지부를 설계 제작하고, 인가된 침입물체의 하중에 따른 신호특성을 고찰하였다. 일반 광통신용인 직경 1.5mm와 3.5mm인 광섬유를 길이 각각 4km를 사용하여 광섬유 굽힘손실을 발생시키는 침입감지 장치를 설계 제작하고, 상용 ROTDR의 조건설정은 파장 1.55㎛, 거리범위 5km, 펄스폭 20 ns, S/N비가 5.7인 시스템으로 실험하였으며, 광섬유 RODTR 센서시스템의 측정신호로부터 침입자 신호를 찾아내기 위한 측정신호처리 시스템을 구성하였다. 광섬유 센서의 인가하중과 광손실값과의 관계는 거의 선형적으로 변함을 보였으며, 공간분해능은 2m로 측정되었고, 침입감지면적은 단위길이당 1.3㎡이고, 감도는 0.17dB/kg으로 외부 침입물체등을 감지하기에 충분히 높은 감도와 감지영역을 가짐을 알 수 있다. The developing of buried fiber optic sensor with high sensitivity and broad-area detecting intruders is carried out using fiber optic ROTDR(Rayleigh Optical Time Domain Reflectometry). The sensing part was designed to be able to broad-area detect intrusion effect per optical fiber length underground. The bending light losses in optical fibers are investigated by commercial mini ROTDR with wavelength 1.55㎛, distance range 5km, pulse width 20ns, SNR=5.7. The sensing fibers are selected as the common telecommunication fibers are the 1.5mm, 3.5 mm outer diameter, 4km each length fiber products. Experiments were investigate the characteristics of signal sensitivity according to applied intrusion weight. The relation between the applied weight and the bending loss was almost linear, and broad-area detect intrusion effects are the 2m resolution and 1.3㎡ per optical fiber length respectively. The light loss by the applied weight on fiber was 0.17 dB/kg, that the sensitivity of the optical fiber sensor was sufficient to detect intruders passing over the buried optical fiber.

인터넷 기반의 구조물 계측시스템 연구

김치엽,최만용,권일범,이승석 한국비파괴검사학회 2003 학술대회 논문집 Vol.- No.1

Structural health monitoring system should developed to be based on internet and database technology in order to manage efficiently large structures. This system is operated by internet connected with the side of structures. The monitoring system has some functions: self monitoring, self diagnosis, and self control etc. Self monitoring is the function of sensor fault detection. If some sensors are not normally worked, then this system can detect the fault sensors. Also Self diagnosis function repair the abnormal condition of sensors. And self control is the repair function of the monitoring system. Especially, the monitoring system can identify the replacement of sensors. For further study, the real application test will be performed to check some unconvinrences.

광섬유 ROTDR 센서를 이용한 사회기반시설물의 보안에 관한 연구

박형준,고광락,권일범 한국비파괴검사학회 2003 한국비파괴검사학회지 Vol.23 No.2

광섬유 ROTDR(Rayleigh optical time domain reflectometry) 센서를 이용하여 중요 보안 대상체인 사회기반시설물에 침투하는 침입자의 위치와 무게 정도를 탐지할 수 있는 기초 연구를 수행하였다. 넓은 면적을 감지할 수 있는 매설형 광섬유 센서탐지판을 제작하고, 인가된 침입물체의 위치와 무게에 따른 신호특성을 고찰하였다. ROTDR 센서는 펄스 폭이 30 ㎱이고, 광섬유의 길이는 10㎞ 이상이다. 위치탐지오차는 약 3m 이내였으며, 무게에 따른 탐지능력은 20kgf, 40kgf, 60kgf의 세단계를 구분할 수 있음을 알 수 있었다. A detection technique is studied to determine the location and the weight of an intruder into infrasturcture using fiber optic ROTDR(Rayleigh optical time domain reflectometry) sensor. Fiber optic sensing plates buried in sand are prepared to measure the intruder effects. The signal of ROTDR was analyzed to confirm the detection performance. The constructed ROTDR system could be used up to 12 ㎞ at the pulse width of 30 ㎱. The location error was less than 3 m and the weight could be detected into three levels of grade, such as 20 kgf, 40 kgf and 60 kgf.

Distributed Measurements of Structures by Fiber Optic Sensors

Il-Bum Kwon 대한토목학회 2003 KSCE journal of civil engineering Vol.7 No.6