• 한국컴퓨터정보학회논문지
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• 제26권5호
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• pp.9-16
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• 2021

본 논문에서는 디지털 트윈 기반의 건물 관제 시스템에 활용할 수 있는 건물탐사 드론을 제안한다. 기존 건물 관제 시스템은 고정된 센서 박스를 통해 관제 정보를 관리하므로 관리 체계의 사각지대가 발생하는 문제점과 순찰을 통한 인위적인 방법은 자원적 한계성을 가진다. 본 논문은 온습도 센서와 가스 누출 탐지 센서를 내장한 드론을 통하여 관제 사각지대를 중심으로 건물의 내부 경로를 탐색하고 영상과 더불어 실시간으로 정보를 전송하여 관제 시스템의 문제점을 극복하고자 한다. 또한, 옵티컬 플로어 센서를 이용한 안정적인 호버링 기능을 가지며 기존 디지털 트윈 기반의 건물 관제 시스템에 적용할 수 있게 한다. 본 연구의 결과는 드론 활용을 통하여 향후 디지털 트윈 관제 시스템의 질적 향상에 많은 도움이 될 것으로 사료된다.

• 한국소음진동공학회논문집
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• 제26권1호
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• pp.89-96
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• 2016

TDOA(time delay of arrival) position estimate from acoustic measurement of artillery shell impact is studied in order to develop a targeting evaluation system. Impact position is calculated from the intersections of hyperbolic estimates based on the least square Taylor series method. The mathematical process of Taylor series estimation is known to be robust. However, the concern lays with the accuracy because it is sensitive to the bias caused by the randomness of measurement situation. The measurement error typically occurs from the distortion of waveform, change of travelling path, and sensor position error. For outdoor measurement, a consideration should be made on the atmospheric condition such as temperature and wind which can possibly change the trajectories of rays of sound. It produces wrong propagation time events accordingly. Ray tracing and optimization techniques are introduced in this study to minimize the bias induced by the ray of sound. The numerical simulation shows that the atmospheric correction improves the estimation accuracy.

• 센서학회지
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• 제7권2호
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• pp.103-110
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• 1998

강유전체 박막과 마이크로 가공기술을 이용하여 초전형 적외선 센서를 제작하였다. 초전형 적외선 센서는 $Pb_{l-x}La_{x}Ti_{1-x/4}O_{3}$ (x=0.05) (PLT) 강유전체 박막 커패시터를 RF 마그네트론 스퍼터링 방식으로 백감 전극이 증착된 MgO 기판상에 결정 성장시킨 구조를 갖고 있다. 스퍼터링된 PLT 박막은 높은 c-축 결정 구조를 가지므로 센서로 사용하기 위한 분극 처리 과정이 필요 없다. 이는 적외선 이미지 센서를 구현함에 있어서 수율 향상에 필수적인 요소이다. 또한 마이크로 가공 기술을 사용하여 센서의 열용량을 극소화함으로서 센서의 효율을 최대화하였다. 제작된 센서의 상부에 폴리이미드를 코팅하고 MgO 기판을 선택적으로 식각하여 코팅된 폴리이미드와 MgO가 강유전체 박막 커패시터를 지지하고 있는 구조를 구현하였다. 이렇게 제작된 센서의 감도는 상온에서 $8.5{\times}10^{8}cm{\cdot}\sqrt{Hz}/W$로 측정되었으며 이는 마이크로 가공 기술을 사용하지 않은 경우보다 약 100 배의 감도 향상을 가져왔다. 2차원 배열 구조를 갖는 센서를 가지고 인체의 유 무 뿐만 아니라 위치까지 감별할 수 있는 센싱 시스템을 구현하였다.

• Smart Structures and Systems
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• 제18권5호
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• pp.1029-1062
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• 2016

In this research, the nonlinear free vibration analysis of boron-nitride micro ribbon (BNMR) on the Pasternak elastic foundation under electrical, mechanical and thermal loadings using modified strain gradient theory (MSGT) is studied. Employing the von $K{\acute{a}}rm{\acute{a}}n$ nonlinear geometry theory, the nonlinear equations of motion for the graphene micro ribbon (GMR) using Euler-Bernoulli beam model with considering attached mass and size effects based on Hamilton's principle is obtained. These equations are converted into the nonlinear ordinary differential equations by elimination of the time variable using Kantorovich time-averaging method. To determine nonlinear frequency of GMR under various boundary conditions, and considering mass effect, differential quadrature element method (DQEM) is used. Based on modified strain MSGT, the results of the current model are compared with the obtained results by classical and modified couple stress theories (CT and MCST). Furthermore, the effect of various parameters such as material length scale parameter, attached mass, temperature change, piezoelectric coefficient, two parameters of elastic foundations on the natural frequencies of BNMR is investigated. The results show that for all boundary conditions, by increasing the mass intensity in a fixed position, the linear and nonlinear natural frequency of the GMR reduces. In addition, with increasing of material length scale parameter, the frequency ratio decreases. This results can be used to design and control nano/micro devices and nano electronics to avoid resonance phenomenon.

• 한국컴퓨터정보학회논문지
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• 제24권6호
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• pp.109-115
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• 2019

Smart Factory is a part of and a key point of the 4th industrial revolution. It performs optimization from the whole viewpoint, using comprehensive data of the post-process data by utilizing various sensors, controllers, and mobile devices beyond the existing factory automation level. In this paper, we design and implement an IoT platform that can detect the safety factors of the workers, the environmental factors of the factory, and real time monitoring at the control center, among the fields to implement smart factory. To accomplish this, we construct a monitoring device that provides sensor information control, server transmission of sensor information, and visualization of collected information. By using this system, it is possible to maintain the temperature and humidity for the optimum working environment in the factory. and also, By using the beacon, it is possible to measure the working time of the worker and trace the position.

• 한국농업기계학회:학술대회논문집
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• 한국농업기계학회 2017년도 춘계공동학술대회
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• pp.156-156
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• 2017

Most crop damages have been occurred by vermin(e.g., wild birds and herbivores) during the period between seeding and the cotyledon level. In this study, to minimize the damage by vermin and acquire the benefits such as protection against weeds and maintenance of water content in soil, immediately vinyl mulching after seeding was devised. Vinyl mulching has been generally covered with black color vinyl, that crop seeding locations cannot be detected by visible light range. Before punching vinyl, non-contact and non-destructive methods that can continuously determine the locations are necessary. In this study, a crop position detection method was studied that uses infrared thermal image sensor to determine the cotyledon position under vinyl mulch. The moving system for acquiring image arrays has been developed for continuously detecting crop locations under plastic mulching on the field. A sliding mechanical device was developed to move the sensor, which were arranged in the form of a linear array, perpendicular to the array using a micro-controller integrated with a stepping motor. The experiments were conducted while moving 4.00 cm/s speed of the IR sensor by the rotational speed of the stepping motor based on a digital pulse width modulation signal from the micro-controller. The acquired images were calibrated with the spatial image correlation. The collected data were processed using moving averaging on interpolation to determine the frame where the variance was the smallest in resolution units of 1.02 cm. For this study, the spline method was relatively faster than the other polynomial interpolation methods, because it has a lower maximum order of formulation when using a system such as the tridiagonal linear equation system which provided the capability of real-time processing. The temperature distribution corresponding to the distance between the crops was 10 cm, and the more clearly the leaf pattern of the crop was visually confirmed. The frequency difference was decreased, as the number of overlapped pixels was increased. Also the wave pattern of points where the crops were recognized were reduced.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2002년도 춘계학술대회 논문집
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• pp.378-391
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• 2002

A 250mm stroke aerostatic stage, which detects position with laser scale and is driven by linear motor, is made and analyzed positioning error in 20$\pm$ 0.5 $^{\circ}C$ controlled atmosphere, aiming at investigating positioning characteristic of ultra-precision stage. We prove this aerostatic stage has a 10nm micro step resolution by experiment. By means of analyzing laser interferometer system, the scale of measuring error is about 0.2-0.4$\mu\textrm{m}$ according to refractive index error from missing the temperature change. To improve laser interferometer system, compensate refractive index error using measuring data from thermocouple. And, confirm 0.10$\mu\textrm{m}$ repeatability and 0.13 $\mu\textrm{m}$ positioning accuracy using the compensating refractive index. Also, we confirm 0.07 ${\mu}{\textrm}{m}$ repeatability of the stage using capacitive displacement sensor.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2000년도 제15차 학술회의논문집
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• pp.408-408
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• 2000

A parabolic dish concentrator used in a high temperature application of solar energy tracks the sun's movement by two axis sun tracking system. In such a system, sun tracking performance affects the system efficiency directly. Generally the higher the tracking accuracy is, the better the system performance is. A large number of parabolic dish type concentrators has been developed and implemented in the world. However none of them clearly provided a qualitative method of how the accuracy of the sun tracking system can be evaluated. The work presented here is the evaluation of sun tracking performance of parabolic dish concentrator, which follows the sun's movement by the sensor, using computer vision system. We install a camera on the parabolic dish concentrator. While the concentrator follows the sun, sun's images are captured continuously. Then the performance of sun tracking system was evaluated by analyzing the variation of the position of the sun in the images.

• 제어로봇시스템학회논문지
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• 제16권3호
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• pp.215-221
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• 2010

This paper introduces development of location estimation and navigation system of mobile robots using USN and LEGO Mindstorms NXT. Developed system includes location estimation, location and navigation information display and navigation control parts. It used ZigBee based USN which was built with CC2431 chip to locate blind node and implemented fuzzy model to improve ability of calculation of distances from reference nodes and location of mobile robots. This paper proposed combination method of location estimation using USN and encoder which is built in motors of mobile robots. Experimental results showed proposed method is superior to the method which used USN only in location estimation and navigating robots. Developed system can locate current position of mobile robots and monitor information from sensor nodes like temperature, humidity and send control signal to mobile robot to move.

• 정보학연구
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• 제9권1호
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• pp.9-19
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• 2006

Medications or conitive-behavior methods have been mainly used as a treatment of alcoholism. lately the virtualy technology has been applied to the kink of alcoholic disorders. A virtual environment makes him having avility to over come the drink. In this study, we were implemented by making panorama images and 3D object modules using 3D MAX, VRML, JAVA. And the BAR stimulator that composed with a position sensor, head mount display, and audio system, is suggested. To illustrate the physiological difference between a person who has a alcoholism and without a liquor bottle, heart rate was measured during experiment, and also measured a person's HR after the virtual reality training. The system measures the Physiological signals such as ECG, Temperature, analyzes those data automatically. The system has two parts, one is physiological data acquisition part which gets the body signal, and the other one is mobile nuit which includes signal processing and transmission functions, And Bluetooth allows two parts to communicate with each other. we demonstrated the subjective effectiveness of virtual reality psychotherapy through the clinical experiment.