• Title/Summary/Keyword: Measuring sensor

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A Study on Tension for Cables of a Cable-stayed Bridge Damper is Attached (댐퍼가 부착된 사장교의 케이블 장력에 관한연구)

  • Park, Yeon Soo;Choi, Sun Min;Yang, Won Yeol;Hong, Hye Jin;Kim, Woon Hyung
    • Journal of Korean Society of Steel Construction
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    • v.20 no.5
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    • pp.609-616
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    • 2008
  • Recently, many ocean bridges that connect land to island or island to island have been constructed along with the improvement of the nation's economy. Long-span bridges can be categorized as suspension bridge, cable-stayed bridge, arch bridge and truss bridge. In this study, correction with respect to construction error can be presented on site through the monitoring of the cable tension change of real structure for four major construction stages so that construction accuracy, including the management of profiles, can be improved. A vibration method, the so-called indirect method that uses the cable's natural frequency changes from the acceleration sensor installed on the cable, is applied in measuring cable tension. In this study, the estimation formula for the effective length of cable with damper is presented by comparing and analyzing between actual measurement and analysis result for the change of the cable's effective length. By the way, it is known that the reliability of estimating cable tension by applying the former method that uses the net distance from damper to anchorage is low. Therefore, for future reference of the maintenance stage, the presented formula for estimating the effective length of cable can be used as a reference for the rational decision-making, such as the re-tensioning and replacement of cable.

A Model-Fitting Approach of External Force on Electric Pole Using Generalized Additive Model (일반화 가법 모형을 이용한 전주 외력 모델링)

  • Park, Chul Young;Shin, Chang Sun;Park, Myung Hye;Lee, Seung Bae;Park, Jang Woo
    • KIPS Transactions on Computer and Communication Systems
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    • v.6 no.11
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    • pp.445-452
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    • 2017
  • Electric pole is a supporting beam used for power transmission/distribution which accelerometer are used for measuring a external force. The meteorological condition has various effects on the external forces of electric pole. One of them is the elasticity change of the aerial wire. It is very important to perform modelling. The acceleration sensor is converted into a pitch and a roll angle. The meteorological condition has a high correlation between variables, and selecting significant explanatory variables for modeling may result in the problem of over-fitting. We constructed high deviance explained model considering multicollinearity using the Generalized Additive Model which is one of the machine learning methods. As a result of the Variation Inflation Factor Test, we selected and fitted the significant variable as temperature, precipitation, wind speed, wind direction, air pressure, dewpoint, hours of daylight and cloud cover. It was noted that the Hours of daylight, cloud cover and air pressure has high explained value in explonatory variable. The average coefficient of determination (R-Squared) of the Generalized Additive Model was 0.69. The constructed model can help to predict the influence on the external forces of electric pole, and contribute to the purpose of securing safety on utility pole.

A Study on the Application of Drone Based Aeromagnetic Survey System to Iron Mine Site (드론 기반 항공자력탐사 시스템을 이용한 철광산 탐사 적용성 연구)

  • Min, Dongmin;Oh, Seokhoon
    • Journal of the Korean earth science society
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    • v.38 no.4
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    • pp.251-262
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    • 2017
  • The system of magnetic exploration with a drone flight was constructed and applied to the iron mine site. The magnetic probe system installed on the drone used a sensor as Bartington's fluxgate type magnetometer, Mag639 and the A/D converter to collect magnetic intensity values on the tablet PC. The drone flight control module is a highly expandable Pixhawk with allowing 15 minutes of flight by loading 3kg. Experiments on the magnetic field interference range were performed to remove the erroneous effect from the drone with applying RTK GPS to obtain the magnetic intensity value at the accurate position. The accurate location information enabled to obtain the gradient measurement of magnetic field by measuring twice at different altitudes. Also, by using the terrain information, we could eliminate the terrain effect by setting the flight path to fly along the terrain. These results are in line with the field experiments using the nuclear proton magnetometer G-858 of Geometrics Co., Ltd, which adds to the reliability of the drone based aeromagnetic survey system we constructed.

Development and Application of Slime Meter for Evaluation of Slime Thickness in Borehole (굴착공 내 슬라임 두께 평가를 위한 슬라임미터의 개발 및 적용)

  • Hong, Won-Taek;Woo, Gyuseong;Lee, Jong-Sub;Song, Myung Jun;Lim, Daesung;Park, Min-Chul
    • Journal of the Korean Geotechnical Society
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    • v.34 no.10
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    • pp.29-38
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    • 2018
  • The slime formed at the bottom of the borehole causes the excessive displacement and loss of the bearing capacity of the drilled shaft. In this study, the slime meter is developed for the evaluation of the slime based on the electrical properties of the fluid and the slime in the borehole. The slime meter is composed of a probe instrumented with electrodes and temperature sensor and a frame with rotary encoder, so that the slime meter profiles the electrical resistivity compensated with temperature effect along the depth. For the application of the slime meter, three field tests are conducted at a borehole with a diameter of 3 m and a depth of 46.9 m with different testing time and locations. For all the tests, the experimental results show that while electrical resistivities are constantly measured in the fluid, the electrical resistivities sharply increase at the surface of the slime. Therefore, the slime thicknesses are estimated by the differences in the depths of the slime surface and the ground excavation. The experimental results obtained at the same testing point with different testing time show that the estimated thickness of the slime increases by the elapsed time. Also, the estimated slime at the side of the borehole is thicker than that at the center of the borehole. As the slime meter estimates the slime in the borehole by measuring the electrical resistivity with simple equipment, the slime meter may be effectively used for the evaluation of the slime formed at the bottom of the borehole.

Preparation and Characterization of Iron Phthalocyanine Thin Films by Vacuum Sublimation (진공증착법을 이용한 철프탈로시아닌 박막의 합성과 그 특성)

  • Jee, Jong-Gi;Lee, Jae-Gu;Hwang, Dong-Uk;Lim, Yoon-Mook;Yang, Hyun-Soo;Ryu, Haiil;Park, Ha-Sun
    • Applied Chemistry for Engineering
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    • v.10 no.5
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    • pp.644-651
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    • 1999
  • In this experiment the Iron phthalocyanine (FePc) films on Si-wafer and alumina pallet were prepared using vacuum sublimation with conditions of changing reaction time, temperature, and deposition rate. Then, some samples were annealed following annealing. Techniques such as XRD, SEM, and resistance measurement method, were dedicated to characterize the changes of surface structure, phase transformation and electric resistance sensitivity in accordance with change of film thickness. In proportion to the decrease of deposition temperature from $370^{\circ}C$ to $350^{\circ}C$, intensities of (200), (011), (211) and (114) planes of $\alpha$-phase were decreased and (100) plane of $\beta$-phase were appeared. The film thickness were controlled by regulating the volume of precursor material during rapid deposition. As a result, it was observed that crystalline particle size had been increased according to the increase of film thickness and $\alpha$-phase transformed to $\beta$-phase. In consequence of measuring the crystallinity of films annealed between $150^{\circ}C$ and $350^{\circ}C$, $\alpha$- to $\beta$-phase transformation was appeared to begin at $150^{\circ}C$ and completely transformed to $\beta$-phase at $350^{\circ}C$. Electric resistance sensitivity of FePc film to $NO_x$ gas along temperature change of FePc films was observed to be more stable with the decrease of the film thickness.

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A Study on Iris Image Restoration Based on Focus Value of Iris Image (홍채 영상 초점 값에 기반한 홍채 영상 복원 연구)

  • Kang Byung-Jun;Park Kang-Ryoung
    • Journal of the Institute of Electronics Engineers of Korea SP
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    • v.43 no.2 s.308
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    • pp.30-39
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    • 2006
  • Iris recognition is that identifies a user based on the unique iris texture patterns which has the functionalities of dilating or contracting pupil region. Iris recognition systems extract the iris pattern in iris image captured by iris recognition camera. Therefore performance of iris recognition is affected by the quality of iris image which includes iris pattern. If iris image is blurred, iris pattern is transformed. It causes FRR(False Rejection Error) to be increased. Optical defocusing is the main factor to make blurred iris images. In conventional iris recognition camera, they use two kinds of focusing methods such as lilted and auto-focusing method. In case of fixed focusing method, the users should repeatedly align their eyes in DOF(Depth of Field), while the iris recognition system acquires good focused is image. Therefore it can give much inconvenience to the users. In case of auto-focusing method, the iris recognition camera moves focus lens with auto-focusing algorithm for capturing the best focused image. However, that needs additional H/W equipment such as distance measuring sensor between users and camera lens, and motor to move focus lens. Therefore the size and cost of iris recognition camera are increased and this kind of camera cannot be used for small sized mobile device. To overcome those problems, we propose method to increase DOF by iris image restoration algorithm based on focus value of iris image. When we tested our proposed algorithm with BM-ET100 made by Panasonic, we could increase operation range from 48-53cm to 46-56cm.

Development of Android-Based Photogrammetric Unmanned Aerial Vehicle System (안드로이드 기반 무인항공 사진측량 시스템 개발)

  • Park, Jinwoo;Shin, Dongyoon;Choi, Chuluong;Jeong, Hohyun
    • Korean Journal of Remote Sensing
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    • v.31 no.3
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    • pp.215-226
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    • 2015
  • Normally, aero photography using UAV uses about 430 MHz bandwidth radio frequency (RF) modem and navigates and remotely controls through the connection between UAV and ground control system. When using the exhausting method, it has communication range of 1-2 km with frequent cross line and since wireless communication sends information using radio wave as a carrier, it has 10 mW of signal strength limitation which gave restraints on life my distance communication. The purpose of research is to use communication technologies such as long-term evolution (LTE) of smart camera, Bluetooth, Wi-Fi and other communication modules and cameras that can transfer data to design and develop automatic shooting system that acquires images to UAV at the necessary locations. We conclude that the android based UAV filming and communication module system can not only film images with just one smart camera but also connects UAV system and ground control system together and also able to obtain real-time 3D location information and 3D position information using UAV system, GPS, a gyroscope, an accelerometer, and magnetic measuring sensor which will allow us to use real-time position of the UAV and correction work through aerial triangulation.

Extraction of Ocean Surface Current Velocity Using Envisat ASAR Raw Data (Envisat ASAR 원시자료를 이용한 표층 해류 속도 추출)

  • Kang, Ki-Mook;Kim, Duk-Jin
    • Korean Journal of Remote Sensing
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    • v.29 no.1
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    • pp.11-20
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    • 2013
  • Space-borne Synthetic Aperture Radar(SAR) has been one of the most effective tools for monitoring quantitative oceanographic physical parameters. The Doppler information recorded in single-channel SAR raw data can be useful in estimating moving velocity of water mass in ocean. The Doppler shift is caused by the relative motion between SAR sensor and the water mass of ocean surface. Thus, the moving velocity can be extracted by measuring the Doppler anomaly between extracted Doppler centroid and predicted Doppler centroid. The predicted Doppler centroid, defined as the Doppler centroid assuming that the target is not moving, is calculated based on the geometric parameters of a satellite, such as the satellite's orbit, look angle, and attitude with regard to the rotating Earth. While the estimated Doppler shift, corresponding to the actual Doppler centroid in the situation of real SAR data acquisition, can be extracted directly from raw SAR signal data, which usually calculated by applying the Average Cross Correlation Coefficient(ACCC). The moving velocity was further refined to obtain ocean surface current by subtracting the phase velocity of Bragg-resonant capillary waves. These methods were applied to Envisat ASAR raw data acquired in the East Sea, and the extracted ocean surface currents were compared with the current measured by HF-radar.

Fabrication and Optimization of a Fiber-optic Dosimeter for Proton Beam Therapy Dosimetry (의료용 양성자선 계측을 위한 광섬유 방사선량계의 제작 및 최적화)

  • Jang, Kyoung-Won;Cho, Dong-Hyun;Yoo, Wook-Jae;Seo, Jeong-Ki;Lee, Bong-Soo;Hwang, Eui-Jung;Shin, Dong-Ho;Park, Sung-Yong
    • Progress in Medical Physics
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    • v.21 no.1
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    • pp.29-34
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    • 2010
  • In this study, we have fabricated a fiber-optic dosimeter for a proton beam therapy dosimetry. We have measured scintillating lights with the various kinds of organic scintillators and selected the BCF-12 as a sensor-tip material due to its highest light output and peak/plateau ratio. To determine the optimum diameter of BCF-12, we have measured scintillating lights according to the energy losses of proton beams in a water phantom. Also, we determined the adequate length of organic scintillator by measuring scintillating lights according to the incident angles of proton beam. Using an optimized fiber-optic dosimeter, we have measured scintillating lights according to the dose rates and monitor units of proton accelerator.

Wearable wireless respiratory monitoring system (의복착용형 무선 호흡모니터 시스템)

  • Lee, In-Kwang;Kim, Seong-Sik;Jang, Jong-Chan;Kim, Koon-Jin;Kim, Kyung-Ah;Lee, Tae-Soo;Cha, Eun-Jong
    • Journal of Sensor Science and Technology
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    • v.17 no.2
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    • pp.133-142
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    • 2008
  • Respiration is induced by muscular contraction of the chest and abdomen, resulting in the abdominal volume change. Thus, continuous measurement of the abdominal dimension enables to monitor breathing activity. Conductive rubber cord has been previously introduced and tested to develop wearable application for respiratory measurements. The present study implemented wireless wearable respiratory monitoring system with the conductive rubber cord in the patient's pants. Signal extraction circuitry was developed to obtain the abdominal circumference changes reflecting the lung volume variation caused by respiratory activity. Wireless transmission was followed based on the zigbee communication protocol in a size of 65mm${\times}$105mm easily put in pocket. Successful wireless monitoring of respiration was performed in that breathing frequency was accurately estimated as well as different breathing patterns were easily recognized from the abdominal signal. $CO_2$ inhalation experiment was additionally performed in purpose of quantitative estimation of tidal volume. Air mixed with $0{\sim}5%\;CO_2$was inhaled by 4 normal males and the respiratory air flow rate, abdominal dimension change, and end tidal $CO_2$ concentration were simultaneously measured in steady state. $CO_2$ inhalation increased the tidal volume in normal physiological state with a correlation coefficient of 0.90 between the tidal volume and the end tidal $CO_2$ concentration. The tidal volume estimated from the abdominal signal linearly correlated with the accurate tidal volume measured by pneumotachometer with a correlation coefficient of 0.88 with mean relative error of approximately 8%. Therefore, the tidal volume was accurately estimated by measuring the abdominal dimension change.