• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2006년도 춘계 학술발표회 논문집
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• pp.1100-1109
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• 2006

In this study, two different technologies which can measure temperature simultaneously at many points are introduced. One is to use a thermal sensor cable that is comprised of addressable thermal sensors connected in parallel within a single cable. The other is to use an optic fiber with Distributed Temperature Sensing (DTS) system. The difference between two technologies can be summarized as follows. A thermal sensor cable has a concept of 'point sensing' that can measure temperature at accurate position of a thermal sensor. So the accuracy and resolution of temperature measurement are up to the ability of the thermal sensor. Whereas optic fiber sensor has a concept of 'distributed sensing' because temperature is measured by ratio of Stokes and anti-Stokes component intensities of Raman backscatter that is generated when laser pulse travels along an optic fiber. It's resolution is determined by measuring distance, measuring time and spatial resolution. The purpose of this study is that application targets of two temperature measurement techniques are checked in technical and economical phases by examining the strength and weakness of them. Considering the functions and characteristics of two techniques, the thermal sensor cable will be suitable to apply to the assessment of groundwater flow, geothermal distribution and grouting efficiency within 300m distance. It is expected that the optic fiber sensor can be widely utilized at various fields (for example: pipe line inspection, tunnel fire detection, power line monitoring etc.) which need an information of temperature distribution over relatively long distance.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2001년도 ICCAS
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• pp.94.3-94
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• 2001

A sensor system was developed to measure displacement of civil structure at a long distance. A He-Ne Laser tube and photodiodes ware used for non-contact measurement. This system allows real time vibration displacement measurement of bridges. The measured displacement data is displayed on computer monitor graphically and also in digit. The accuracy of the displacement measurement shows 2mm in vertical vibration. It shows remote inspection of the vibration of long bridges and buildings.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2012년도 추계학술대회
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• pp.261-262
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• 2012

본 연구에서는 레저선박 및 소형선박을 위한 지능형 충돌방지 시스템에 대한 언급하고 있다. 이 시스템의 기능은 선박으로부터 이동 물체까지의 거리와 속도를 추정하고 해당 물체와의 충돌을 회피하기 위한 제어신호를 발생하는 것이다. 본 논문에서는 칼만필터를 이용하여 대상물체의 위치와 속도를 추정하는 방법에 대해 소개한다. 실제 실험단계에서는 레이저센서를 이용하여 대상물체의 거리를 계측하고 계측된 신호에 필터링을 적용하여 대상물의 위치와 속도를 검출하게 된다. 제안한 기법의 유용성을 검증하기 위해 물체의 위치 및 속도추정에 대한 시뮬레이션을 수행하였다.

• 반도체디스플레이기술학회지
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• 제7권4호
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• pp.1-5
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• 2008

There is a need to enlarge the mother glass substrate in OLED to raise its productivity and to realize OLED TV. On the other hand, some difficulties may arise regarding the deflection of a large glass substrate during its handling operation due to its thinness $(0.5\sim0.7t)$, which is not even enough to allow it to stand its own mass. This thesis proposes a conceptual plan for the application of the clamping- and bending-end conditions to the glass substrate handler. To verify proposed plan, the non-contact 3 dimensional measuring instrument is developed. The composition of the 3 dimensional measuring instrument measures shape of the product using X-Y stage robot and laser distance sensor. X-Y stage robot and laser distance sensor are controlled by LabVIEW language. To calibrate measuring instrument, the direction conversion of the Euler angle was used. In order to confirm deflection of the glass substrate, the experiment was carried out at the bending end boundary condition and the proposed effect was verified.

• Agricultural and Biosystems Engineering
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• 제2권2호
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• pp.69-74
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• 2001

Detection of operation lines in farm works, object recognition and obstacle avoidance are essential pre-requisite technologies for unmanned agricultural machinery. A CCD camera, which has been largely used for these functions, is expensive and has difficulty in real-time signal processing. In this study, a laser range sensor was selected as the guiding vision for unmanned agricultural machinery such as a tractor. To achieve this capability, algorithms for distance measurement, signal filtering, object recognition, and obstacle avoidance were developed. Computer simulations were carried out to evaluate performance of the algorithms. Experiments were also conducted with various materials and shapes, Laser beam lost its intensity for poor reflective materials, resulting in less range value than actual, so a compensation technique was considered to be necessary. Object detection system was fabricated on an agricultural tractor and the performance was evaluated. As test result for obstacle detection and avoidance in field, to detect and avoid obstacle for path finding with guiding system for unmanned agricultural machinery was enable.

• 한국지능시스템학회논문지
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• 제23권1호
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• pp.35-45
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• 2013

자동차의 자율주행기능 실현을 위해서는 기존의 지능형자동차 인식시스템 보다 강인하고 우수한 성능의 주행환경 인식시스템이 요구된다. 특히, 카메라와 레이저레이더 센서는 물체의 특징, 거리 등의 정보를 제공하는 대표적인 주행환경인식 센서로, 이를 이용한 단일센서기반 인식시스템 연구가 활발히 이루어지고 있다. 일반적으로 레이저레이더 센서의 거리정보는 도로의 구조, 차량, 보행자 등의 인식을 위하여 많이 사용되며, 카메라의 영상정보는 차선, 횡단보도, 표지판 등의 주행환경 인지에 사용된다. 하지만, 단일센서기반 인식시스템은 센서의 특성 및 주행환경에 의한 오검출 또는 미검출 발생률이 높기 때문에 자율주행기능 구현에 적합하지 않다. 따라서 단일센서기반의 인식시스템의 한계를 극복하기 위하여 카메라, 레이저레이더, GPS 등을 이용한 정보융합 인식시스템 개발이 필수적이다. 이 연구에서는 영상 및 레이저레이더의 정보융합을 통해 강인한 차선인식, 횡단보도 인식 등을 수행하는 자율주행자동차의 주행환경 인식기술을 개발하였다. 이 연구를 통해 개발된 주행환경 인식기술은 자율주행자동차에 적용되어 다양한 주행시험을 통해 신뢰성 및 안정성이 검증되었다.

• 대한공간정보학회지
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• 제16권2호
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• pp.87-95
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• 2008

Ladar (LAser Detection And Ranging, Lidar)는 레이저 신호를 이용하여 대상지역에 대하여 정밀한 3차원 거리를 취득하는 센서로 최근 들어 미사일, 항공기 등에 탑재되어 자동표적인식 등에 활용되고 있다. 기존의 영상기반센서와 달리 센서와 표적과의 거리를 밝기나 색상 값으로 표현한 range 영상을 제공하며, 이로부터 표적의 정밀한 3차원 모델의 생성이 가능하기 때문에 표적의 인식과 식별을 가능하게 한다. 이러한 Ladar 센서의 데이터를 모의 생성한다면, 센서의 개선 및 개발 또는 센서 데이터 처리 알고리즘의 개발을 더욱 효율적으로 수행할 수 있게 될 것이다. 이에 본 연구에서는 특히 Linear FM 기반의 Ladar 센서의 신호 생성 및 신호처리 과정을 시뮬레이션하여 Ladar 영상을 모의 생성하고자 한다. 이를 위해 본 연구에서는 우선 FM chirp modulator를 탑재한 시스템의 레이저 신호를 모의로 생성하고, FFT기반 신호처리를 통해 센서와 표적과의 거리를 획득하였으며, 최종적으로 Ladar range 영상을 성공적으로 모의 생성하였다.

• 제어로봇시스템학회논문지
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• 제20권11호
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• pp.1170-1174
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• 2014

This paper suggests using the ICP (Iterative Closet Point) algorithm to compensate a two-dimensional map. ICP algorithm is a typical algorithm method using matching distance data. When building a two-dimensional map, using data through the value of a laser scanner, it occurred warping and distortion of a two-dimensional map because of the difference of distance from the value of the sensor. It uses the ICP algorithm in order to reduce any error of line. It validated the proposed method through experiment involving matching a two-dimensional map based reference data and measured the two-dimensional map.

• 대한기계학회논문집
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• 제18권3호
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• pp.529-539
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• 1994

In laser heat treatment process of steels, the thin layer of substrate is rapidly heated to the austenitizing temperature and subsequently cooled at a very fast rate due to the self-quenching effect. Consequently, it is transformed to martensitic structure which has low magnetic permeability. This observation facilitates the use of a sensor measuring the change of electromagnetic field induced by the hardening layer. In this paper, the eddy-current electromagnetic field is analyzed by a finite element method. The purpose of this analysis is to investigate how the electrical impedance of the sensor's sensing coil varies with the change in permeability. To achieve this, a numerical model is formulated, taking into consideration the hardening depth, distance of the sensor from the hardened surface and the frequency driving the sensor. The results obtained by numerical simulation show that the eddy-current measurement method can feasibly be used to measure the changing hardening depth within the frequency range from 10 kHz to 50 kHz.

• 대한임베디드공학회논문지
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• 제15권5호
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• pp.215-225
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• 2020

Light detection and ranging (LiDAR) sensors detect the distance of the surrounding environment and objects. Conventional LiDAR sensors require a certain amount of a power because they detect objects by transmitting lasers at a regular interval depending on a constant resolution. The constant power consumption from operating multiple LiDAR sensors is detrimental to autonomous and electric vehicles using battery power. In this paper, we propose two algorithms that improve the inefficient power consumption during the constant operation of LiDAR sensors. LiDAR sensors with algorithms efficiently reduce the power consumption in two ways: (a) controlling the resolution to vary the laser transmission period (T_P) of a laser diode (LD) depending on the vehicle's speed and (b) reducing the static power consumption using a sleep mode depending on the surrounding environment. A proposed LiDAR sensor with a resolution control algorithm reduces the power consumption of the LD by 6.92% to 32.43% depending on the vehicle's speed, compared to the maximum number of laser transmissions (N_x·max). The sleep mode with a surrounding environment-sensing algorithm reduces the power consumption by 61.09%. The proposed LiDAR sensor has a risk factor for 4-cycles that does not detect objects in the sleep mode, but we consider it to be negligible because it immediately switches to an active mode when a change in surrounding conditions occurs. The proposed LiDAR sensor was tested on a commercial processor chip with the algorithm controlling the resolution according to the vehicle's speed and the surrounding environment.