• Journal of the Optical Society of Korea
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• 제20권1호
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• pp.180-187
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• 2016

The independent operation of a color filter for incident polarization is demonstrated using a guided-mode resonance (GMR) filter employing a metal-insulator-metal (MIM) waveguide. To achieve independent operation, a rectangular MIM grating is proposed as a wave-guide resonator. The design considerations are discussed and include how to determine the grating period and slit width. Power flow distribution is observed with slit width variation. Blue-green, green-red, and blue-red filters for corresponding x- and y-polarizations are demonstrated as application examples with numerical simulation with rectangle-shaped MIM grating. As a practical application, feasibility as a chromatic polarizer is discussed.

• 구강회복응용과학지
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• 제30권3호
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• pp.246-252
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• 2014

통상적인 임플란트 치료는 식립 후 약 3 - 5개월 뒤 임플란트 상부 보철물을 제작한다. 이러한 치료과정의 단점으로는 환자가 임플란트 식립 후 보철물이 장착되는 최종 치료 시점까지의 기간 동안 유지력과 저작능력이 떨어지는 임시의 치를 사용하여 생활해야 한다는 것이다. 최근의 임플란트 식립 후 즉시 부하 보철물 치료는 시술 적응증에 따른 제한이 있긴 하지만, 잦은 치과 방문이 어렵고 진료에 대한 협조도가 낮은 정신적, 신체적 장애 환자들에게 더욱 유용하다고 생각된다. 본 증례에서는 삼차원 컴퓨터 유도 수술법을 이용한 임플란트 식립 후 즉시 부하 보철치료를 정신지체장애 환자에서 시행하였으며, 시술 후 좋은 경과를 보였기에 이를 보고하는 바이다.

• 한국의학물리학회지:의학물리
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• 제13권4호
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• pp.218-223
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• 2002

두개외 병소 즉, 척추 등에 발생한 종양 혹은 혈관기형 등의 병소에 대해 침습적 수술이 불가한 경우 정위적 방사선 수술이 임상에서 시도되고 있다. 본 연구는 실험적으로 팬텀에 대해 척추 정위 방사선수술을 시행하고 결과 분석을 통하여 두개외 수술 목표점에 대한 방사선수술 위치 정확도를 평가하고자 한다. 이 실험을 위하여 팬텀을 특별히 고안하였으며 수술실에서 방사선 수술 목표점의 위치는 광학적 추적 장치를 이용하여 결정하였고 3 mm 미세다엽시준기(mMLC; mcro Multi-Leaf Collimator)를 사용하여 시술하였다. 팬텀의 목표점에 대한 방사선수술 오차는 $\pm$1 mm 이내였으며 분할방사선 수술 경우도 $\pm$1 mm 이내였다. 결과적으로 광학적 위치추적 장치를 이용한 두개외 목표점의 방사선 수술은 매우 정확하고 유용한 방법으로 판단된다.

• International Journal of Fuzzy Logic and Intelligent Systems
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• 제2권3호
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• pp.242-247
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• 2002

According to increase of the factory-automation(FA) in the field of production, the importance of the autonomous guided vehicle's(AGV) role has also increased. This paper is about an active and effective controller which can flexibly prepare for changeable circumstances. For this study, research about an behavior-based system evolving by itself is also being considered. In this Paper, we constructed an active and effective AGV fuzzy controller to be able to carry out self-organization. To construct it, we tuned suboptimally membership function using a genetic algorithm(GA) and improved the control efficiency by self-correction and the generation of control rules.

• Corrosion Science and Technology
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• 제4권3호
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• pp.108-113
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• 2005

One of the recent safety issues in the pressurized heavy water reactor (PHWR) is the cracking of the feeder pipe. Because of the limited accessibility to the cracked region and a high dose of radiation exposure, it is difficult to inspect all the pipes with the conventional ultrasonic method. In order to solve this problem, a long-range guided wave technique has been developed. A computer program to calculate the dispersion curves in the pipe was developed and the dispersion curves for the feeder pipes in PHWR plants were determined. Several longitudinal and/or flexural modes were selected from the review of the dispersion curves and an actual experiment has been carried out with the specific alignment of the piezoelectric ultrasonic transducers. They were confirmed as L(0,1)) and/or flexural modes(F(m,2)) by the short time Fourier transformation(STFT) and were sensitive to the circumferential cracks, but not to the axial cracks in the pipe. An electromagnetic acoustic transducers(EMAT) was designed and fabricated for the generation and reception of the torsional guided wave. The axial cracks were detected by a torsional mode(T(0,1)) generated by the EMAT.

• 로봇학회논문지
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• 제14권1호
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• pp.40-49
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• 2019

Reinforcement learning has been applied to various problems in robotics. However, it was still hard to train complex robotic manipulation tasks since there is a few models which can be applicable to general tasks. Such general models require a lot of training episodes. In these reasons, deep neural networks which have shown to be good function approximators have not been actively used for robot manipulation task. Recently, some of these challenges are solved by a set of methods, such as Guided Policy Search, which guide or limit search directions while training of a deep neural network based policy model. These frameworks are already applied to a humanoid robot, PR2. However, in robotics, it is not trivial to adjust existing algorithms designed for one robot to another robot. In this paper, we present our implementation of Guided Policy Search to the robotic arms of the Baxter Research Robot. To meet the goals and needs of the project, we build on an existing implementation of Baxter Agent class for the Guided Policy Search algorithm code using the built-in Python interface. This work is expected to play an important role in popularizing robot manipulation reinforcement learning methods on cost-effective robot platforms.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제16권1호
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• pp.211-230
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• 2022

In image segmentation, for the condition that objects (targets) and background in an image are intertwined or their common boundaries are vague as well as their textures are similar, and the targets in images are greatly variable, the deep learning might be difficult to use. Hence, a new method based on graph theory and guided feathering is proposed. First, it uses a guided feathering algorithm to initially separate the objects from background roughly, then, the image is separated into two different images: foreground image and background image, subsequently, the two images are segmented accurately by using the improved graph-based algorithm respectively, and finally, the two segmented images are merged together as the final segmentation result. For the graph-based new algorithm, it is improved based on MST in three main aspects: (1) the differences between the functions of intra-regional and inter-regional; (2) the function of edge weight; and (3) re-merge mechanism after segmentation in graph mapping. Compared to the traditional algorithms such as region merging, ordinary MST and thresholding, the studied algorithm has the better segmentation accuracy and effect, therefore it has the significant superiority.

• 대한치과보철학회지
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• 제60권1호
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• pp.44-54
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• 2022

다수 치아의 상실 상태로 장시간 지속시 구치부 지지의 부족 및 치아들의 과정출이 발생되어 교합 부조화, 수직고경 상실 및 기능 장애 등의 심각한 문제가 초래된다. 본 증례는 장기간 다수치아 결손으로 인하여 대합치가 정출하면서 교합평면의 붕괴가 일어난 환자의 완전 구강 회복에 관한 증례이다. 상기 환자는 서울대학교 치과병원 치과보철과로 내원한 68세 남환으로 오래된 상악 의치를 빼다가 치아가 함께 발거되었으며, 하악 전치부가 상악 전치부와 강하게 닿아서 불편함을 호소하며 내원하였다. 여러가지 평가를 통해 수직고경을 4 mm 거상하였으며, 무치악부는 진단 및 치료계획시 설계한 최종 보철 수복물 제작을 고려하여 정확한 임플란트 식립을 위해 CAD-CAM (Computer-aided design-computer-aided manufacturing) 기술을 이용한 Computer guided implant surgery를 시행하고, 임플란트 고정성 보철 수복으로 진행하였고, 환자는 저작, 기능 및 심미 모두 큰 개선에 만족하였다.

• 한국컴퓨터정보학회:학술대회논문집
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• 한국컴퓨터정보학회 2016년도 제54차 하계학술대회논문집 24권2호
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• pp.289-291
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• 2016

본 논문에서는 VR의 발전과 함께 주목받고 있는 컴퓨터 비전 관련 기술들에 대하여 살펴보고, 가장 먼저 선행되어야 하는 이미지 필터링 알고리즘에 대하여 살펴 본다. 다양한 case에서의 여러 Image Filter를 구현, 성능을 비교 분석해 보고, 정확도를 향상 시킬 수 있는 방안에 대하여 연구한다.

• 전기학회논문지
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• 제66권9호
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• pp.1341-1350
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• 2017

In this paper, a high reliability 30W DC-DC converter is designed considering military standard (MIL-STD) for military applications such as guided weapon and aircraft. The performances and specifications of conventional military grade DC-DC converter are practically analyzed. The requirements for military grade DC-DC converter are established in consideration of MIL-STD and analysis results of conventional product. Two isolated DC-DC converter, forward and fly-back converter, are designed and compared to determine topology. From experimental results under various operating conditions, the forward topology satisfied performances and specifications of MIL-STD for military DC-DC converter.