• 한국광학회지
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• 제28권4호
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• pp.146-152
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• 2017

우주용 인공위성 카메라를 구성하는 반사경의 정렬은 광학계의 고분해능, 고성능을 얻기 위한 중요한 과정 중 하나이다. 반사경들의 상호정렬에는 큐브미러(cube mirror)가 대신 사용되기 때문에, 각 반사경과 해당 큐브미러 간의 상호위치관계 정보가 우선 필요하다. 따라서 우주용 카메라 반사경들의 정렬을 위해 각 반사경의 정점과 해당 큐브미러의 상대 좌표값을 정확하게 측정해야하며, 본 논문에서는 컴퓨터 제작 홀로그램(computer-generated hologram, CGH)의 정렬용 세그먼트와 광섬유를 이용하는 새로운 측정 시스템을 제안함으로써 우주용 카메라를 구성하는 반사경의 정점을 요구조건 이내로 측정할 수 있었다. 측정 시스템은 광학계 평가용 간섭계, CGH, 광섬유, 반사경으로 구성되어 있으며, 최종적으로 데오도라이트를 이용해 큐브미러를 기준으로 주 반사경의 정점에 위치한 광섬유 끝단의 3차원 상대 좌표값을 $25{\mu}m$ 이하의 정밀도로 측정할 수 있었다.

• 동력기계공학회지
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• 제17권5호
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• pp.121-127
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• 2013

In this paper, we propose a distance measurement system for automatic berthing control using a stereo camera mounted on a rotation control device, and a radial pattern target. Automatically controlling the position and attitude of a ship aims to prevent maritime accidents due to human error. Our goal is to measure the relative distance between a ship and an onshore or offshore target for berthing. Therefore, the distance should be continuously measured while tracking a fixed point on a target. To this end, we developed a stereo camerabased distance measurement system that satisfied these requirements. This paper describes the structure and principle of the measurement system. We validate the distance error for target incline due to the relative position and attitude between a camera and a target in miniature scale. In addition, the findings of an experiment in an outdoor environment demonstrate that the proposed measurement system has accuracy within 1 m at a range of 20-100 m which is the acceptable accuracy for automatic berthing.

• 한국정밀공학회지
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• 제20권8호
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• pp.62-69
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• 2003

In most shipyards, the measurement of 3-dimensional relative position of pipes should be connected in the block depends on the manual operation. It results a very tedious and inefficient procedure, thus the proper measurement system is needed to improve productivity and accuracy. This paper describes the development of pipe measurement system including system concepts, measuring procedures, system calibration, and its accuracy and productivity. And also, the possibility and things to be improved for application in shipyard are discussed in this paper.

• 한국농업기계학회:학술대회논문집
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• 한국농업기계학회 1996년도 International Conference on Agricultural Machinery Engineering Proceedings
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• pp.1126-1135
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• 1996

This study was conducted to select the sensors for measuring temperature, relative humidity, and air velocity among the major environmental factors affecting the pig productivity as a part of the study for the optimum production system model development of pig-housing. The study results are summarized as the follows : Two sensors , HMP233L and HANI, were tested for measuring temperature and relative humidity , Test results were analyzed by the statistical methods. And the sensor, HMP233L was selected as a proper sensor for temperature sand relative humidity measurement . An air velocity sensor was tested. Test results showed that its accuracy was low and incongruent for the air velocity measurement when it was lower than 4m/s.

• 펄프종이기술
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• 제40권4호
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• pp.10-15
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• 2008

Flocculation phenomena of the stock mixed with cellulosic fibers, fillers and polymers were investigated by a new turbidity measurement system consisted of a probe-type turbidimeter, data acquisition system and computer. The probe-type turbidimeter allowed to measure the real time flocculation of the stock induced by single polymer and microparticle systems. Flocculation phenomena were evaluated by average and final relative turbidity indices. Turbidity and flocculation showed inverse relationship, i.e. the turbidity decreased with the formation of flocs. Relative turbidity of the stock treated with microparticle system was lower than that of the stock containing single polymer system, which indicated that the microparticle system showed greater floc forming efficiency than single polymer system.

• 대한전기학회논문지:전력기술부문A
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• 제48권1호
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• pp.76-81
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• 1999

The degree of relative similarity between 2D patterns is obtained using Open-Ball Scheme. Open-Ball Scheme employs a method of transforming the geometrical information on 3D objects or 2D patterns into the features to measure the relative similarity for object(patten) recognition, with invariance on scale, rotation, and translation. The feature of an object is used to obtain the relative similarity and mapped into [0, 1] the interval of real line. For decades, Moment-Invariant Method has been used as one of the excellent methods for pattern classification and object recognition. Open-Ball Scheme uses the geometrical structure of patterns while Moment Invariant Method uses the statistical characteristics. Open-Ball Scheme is compared to Moment Invariant Method with respect to the way that it interprets two-dimensional patten classification, especially the paradigms are compared by the degree of closeness to human's intuitive understanding. Finally the effectiveness of the proposed Open-Ball Scheme is illustrated through simulations.

• Smart Structures and Systems
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• 제34권1호
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• pp.33-40
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• 2024

We aimed to assess the evolution of small-strain stiffness and relative density in non-compacted embankment layers. We developed embedded type in-situ soil stiffness measurement devices for monitoring small-strain stiffness occurring after filling at a test site and conducted comprehensive laboratory compaction tests using an oedometer cell with a bender element. However, direct comparison is extremely difficult because the shear wave velocity measured in the field and laboratory depend on depth and effective stress, respectively. Therefore, we propose a method for establishing a relationship between effective stress and depth using a compressibility model. In this study, the shear wave velocity measured in the field was compared to the estimated shear wave velocity-depth profiles for completely dry and saturated conditions with different relative densities. The relative density under saturated soil conditions may vary between 50% and 90% and tends to be closer to 95%. Under dry soil conditions, the relative density of the embankment can vary from 30% to 70% and tends to approach 76%. For model validation, the relative density estimated from shear wave velocity-depth profiles was compared to that estimated from DCPI data. In other words, the results analyzed in the context of an effective stress-depth model enable the prediction of engineering properties such as the small-strain stiffness and relative density of embankment layers. This study demonstrates that physics-based data analyses successfully capture the relative density of non-compacted embankment layers.

• 한국항공우주학회지
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• 제43권4호
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• pp.289-295
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• 2015

본 논문은 지상에서 단안 영상센서를 이용하여 항공기의 상대 위치를 측정하는 방법에 대하여 기술하는데, 알고 있는 항공기의 날개전폭과 카메라의 광학 파라미터를 이용하여 상대 거리 및 상대 위치를 측정하는 방법을 제시하였다. 또한 항공기 영상을 추출하기 위하여 차영상 기법을 이용하는 방법을 제시하였다. 이러한 기술은 ILS를 대신할 영상기반 자동착륙 시스템으로 이용될 수 있다. 상대 위치 및 거리 측정 성능을 검증하기 위하여 경비행기와 GPS를 이용하여 성능을 검증하였으며 1.85m의 평균제곱근 오차가 발생함을 확인하였다.

• 한국정밀공학회지
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• 제16권3호통권96호
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• pp.164-173
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• 1999

Robot calibration needs accurate measurements of robot end-effector position at a number of different robot configurations. One of the efficient ways of the measurement is "Touching on Jig" method suggested in [7], which utilizes a touch sensor and a fixture consisting of various sizes of blocks. By moving the end-effector to touch the surface of a block whose position relative to the other is known, the end-effector position relative to the fixture coordinate system can be obtained at the instant of touching. However, the global size of fixture is too small to cover the various configurations of the robot. Because of the manufacturing difficulties, the fixture cannot be manufactured large enough for well distributed position measurement. It results in the improvement of robot accuracy only in the limited space near to the fixture rather than over the whole space of the robot working volume. The paper proposes a method to resolve the above problem by measuring the end-effector positions with respect to several different coordinate system using the same measurement devices. It is found that the proposed method leads the improvements of robot position accuracy over the large space of working volume. The experimental studies are performed to show the validity of the method and their results are discussed.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1998년도 추계학술대회 논문집
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• pp.187-190
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• 1998

In this paper a probe for the' measurement of dielectric properties of dielectric sheet materials is designed and implemented as a coaxial air line type. Using the broadband impedance method with this measurement probe the dielectric constant and loss tangent of the glass-epoxy and teflon are determined in the frequency range of 0.1 - l.O[GHz] with the temperature variation from $25[^{\circ}C]$ up to $65[^{\circ}C]$. A measured relative dielectric constant of the glass-epoxy is 4.42 and a loss tangents is 0.019 relatively, and the relative dielectric constants of teflon is 2.17 and a loss tangents is 0.002 relatively