• Current Optics and Photonics
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• 제5권6호
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• pp.699-710
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• 2021

In this study, we propose a biomimetic optical structure design methodology for investigating micro-optical mechanisms associated with the compound eyes of insects. With these compound eyes, insects can respond fast while maintaining a wide field of view. Also, considerable research attention has been focused on the insect compound eyes to utilize these benefits. However, their nano micro-structures are complex and challenging to demonstrate in real applications. An effectively integrated design methodology is required considering the manufacturing difficulty. We show that photorealistic ray-traced visualization is an effective method for designing the biomimetic of a micro-compound eye of an insect. We analyze the image formation mechanism and create a three-dimensional computer-aided design model. Then, a ray-trace visualization is applied to observe the optical image formation. Finally, the segmented images are stitched together to generate an image with a wide-angle; the image is assessed for quality. The high structural similarity index (SSIM) value (approximately 0.84 to 0.89) of the stitched image proves that the proposed MATLAB-based image stitching algorithm performs effectively and comparably to the commercial software. The results may be employed for the understanding, researching, and design of advanced optical systems based on biological eyes and for other industrial applications.

• Journal of Electrical Engineering and Technology
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• 제10권3호
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• pp.1131-1137
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• 2015

Gallium nitride (GaN) is a promising material for next-generation high-power applications due to its wide bandgap, high breakdown field, high electron mobility, and good thermal conductivity. From a structure point of view, the vertical device is more suitable to high-power applications than planar devices because of its area effectiveness. However, it is challenging to obtain a completely upright vertical structure due to inevitable sidewall slope in anisotropic etching of GaN. In this letter, we design and analyze the enhancement-mode n-channel vertical GaN MOSFET with variation of sidewall gate angle by two-dimensional (2D) technology computer-aided design (TCAD) simulations. As the sidewall slope gets closer to right angle, the device performances are improved since a gradual slope provides a leakage current path through the bulk region.

• Journal of electromagnetic engineering and science
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• 제18권2호
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• pp.108-116
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• 2018

In this paper, a method of designing a Vivaldi type phased array antenna (PAA) which operates at S-band (2.8-3.3 GHz) is presented. The presented antenna uses broadside coupled split ring resonators (BC-SRRs) for high isolation, wide field of view, and good active S-parameter characteristics. As an example, we design a $1{\times}8$ array antenna with various BC-SRR structures using theory and EM simulations. The antenna is fabricated and measured to verify the design. With the BC-SRR implemented between the two radiating elements, the isolation is shown to be enhanced by 6 dB, up to 23 dB. The scan angle is shown to be within ${\pm}53^{\circ}$ based on a -10 dB active reflection coefficient. The operation of the scan angle is possible within ${\pm}60^{\circ}$ with a little larger reflection coefficient (-7 dB to -8 dB). The proposed design with BC-SRRs is expected to be useful for PAA applications.

• Structural Engineering and Mechanics
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• 제81권6호
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• pp.769-780
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• 2022

This paper studies the dynamic behavior of laminated composite circular cylindrical shells interacting with a fluid. The mathematical formulation of the dynamic problem for an elastic body is developed based on the variational principle of virtual displacements and the relations of linear elasticity theory. The behavior of an ideal compressible fluid is described by the potential theory, the equations of which together with boundary conditions are transformed to a weak form. The hydrodynamic pressure exerted by the fluid on the internal surface of the shell is calculated according to the linearized Bernoulli equation. The numerical implementation of the mathematical formulation has been done using the semi-analytical finite element method. The influence of the ply angle and lay-up configurations of laminated composites on the natural vibration frequencies and the hydroelastic stability boundary have been analyzed for shells with different geometrical dimensions and under different kinematic boundary conditions set at their edges. It has been found that the optimal value of the ply angle depends on the level of filling of the shell with a fluid. The obtained results support the view that by choosing the optimal configuration of the layered composite material it is possible to change upwards or downwards the frequency and mode shape, as well as the critical velocity for stability loss over a wide range.

• 한국시조학회지:시조학논총
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• 제22집
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• pp.5-25
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• 2005

이 논문은 국문학사상 최다의 시조(2,254수)를 남긴 다석 유영모와 그의 시조를 국문학계에 최초로 알리고, 그 시조의 특징과 시조사적 의의를 밝히는 것을 목적으로 한다. 육당$\cdot$춘원과 교유하며 동시대를 살았던 다석은 동서양의 사상을 두루 섭렵하고 독자적인 신관을 수립한 위대한 종교사상가였다. 다석은 1955년부터 1974년까지 20년 간 일기를 썼는데, 거기에 2,200수가 넘는 시조를 남겼다. 그의 시조의 특징과 시조사적 의미는 크게 세 가지로 정리될 수 있다. 1) 다석은 국문학사상 최다의 시조를 지었다. 2) 그의 시조의 대부분이 그의 종교사상을 담았다는 특징을 지니는데, 이는 '인간은 악기이고, 하느님은 연주자라는 자신의 믿음과 '자신의 시조에는 죽음을 사모하는 자신의 뜻이 담기기 마련' 이라는 시조관에 기인한다. 자신의 시조를, 하느님이 자신을 연주하여 나오는 음악으로 여긴 것이다 3) 다석 시조의 시어는 대부분이 심오한 의미를 담아 특이하게 구사한 우리말로 되어 있다. 그래서 매우 난해하다. 이것은 그의 사상과 학문이 자연스럽게 유로된 결과다. 다석은 우리에게 '시조는 진리를 담는 최선의 그릇'이 될 수 있다는 시조의 새로운 경지를 보여주었다. 다석의 시조가 지금까지는 국문학사의 영역 바깥에서 방치되어 왔지만, 지금부터라도 심도있게 다루어져야 한다. 다석 시조의 시어, 시세계. 영향관계 등 계속 논의되어야 할 것들이 많다.

• 한국전자통신학회논문지
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• 제19권1호
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• pp.11-18
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• 2024

본 논문에서는 Chebyshev 다항식을 이용해서 차량용 근거리 레이다에서 사용하는 70GHz 대역 배열안테나를 최적 설계하였다. SRR(: Short Range Radar)에서는 근거리 내에 물표를 검출하면서 높은 FoV(: Field of View)를 확보하기 위한 빔폭과 낮은 SLL(: Side lobe level)을 가져야 한다. 최적 설계된 안테나는 76~81GHz에서 동작하며 안테나의 크기를 소형으로 하기 위해 12개의 패치를 직렬로 배열하여 구성하였고, 78GHz에서 SLL - 10dB이하, 안테나의 이득 15.4dB를 만족하고 빔폭 112.5o, 입력반사계수 -10dB이하의 성능을 갖는다. 본 논문에서는 Chebyshev 다항식을 이용해서 SRR을 위한 안테나의 설계를 진행하고 이를 기반으로 MRR과 LRR에 사용될 안테나 구조 설계를 위한 최적 설계법을 제시한다.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2004년도 Asia Display / IMID 04
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• pp.26-29
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• 2004

S-PVA is a new technology which enables screen quality advantages over S-IPS and MVA, including high transmittance, >1000:1 contrast ratio, sub-10ms response time, and wide angle of view with no off-axis image inversion and undetectable gamma distortion. This new technology will be described in detail. This paper also addresses the other remaining performance issues facing LCD-TV, including Samsung's plans for addressing these challenges. For example, until recently, inter-gray response time and associated motion blur were significant issues for achieving LCD-TV images quality. Samsung has invented DCC-II technology to achieve sub-10ms response time, and this achievement is described herein. Other technology advancements, including next-generation color performance and ultra-low black performance and improvement of off axis image quality are also discussed in this paper.

• 디지털산업정보학회논문지
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• 제6권3호
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• pp.131-139
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• 2010

Virtual reality(VR) technology allows users to experience the same sensation as if they look and feel real objects, and furthermore it enables users to experience phenomena in virtual environment which are difficult to illustrate in real world. A multichannel display is one of the virtual reality systems for generating high-quality images and guaranteeing a wide view angle using multiple projectors. In this work, we present the multichannel display system whose resolution is $4096{\times}1536$. We implement an automatic calibration (geometric and color) method for compensating the distorted image and color. The results clearly show the proposed system provides continuous and smooth images.

• 전기학회논문지
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• 제62권9호
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• pp.1270-1275
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• 2013

A lot of research about camera calibration and lens distortion for wide-angle lens has been made. Especially, calibration for fish-eye lens which has 180 degree FOV(field of view) or above is more tricky, so existing research employed a huge calibration pattern or even 3D pattern. And it is important that calibration parameters (such as distortion coefficients) are suitably initialized to get accurate calibration results. It can be achieved by using manufacturer information or lease-square method for relatively narrow FOV(135, 150 degree) lens. In this paper, without any previous manufacturer information, camera calibration and barrel undistortion for fish-eye lens with over 180 degree FOV are achieved by only using one calibration pattern image. We applied QR decomposition for initialization and Regularization for optimization. With the result of experiment, we verified that our algorithm can achieve camera calibration and image undistortion successfully.

• 한국감성과학회:학술대회논문집
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• 한국감성과학회 2000년도 춘계 학술대회 및 국제 감성공학 심포지움 논문집 Proceeding of the 2000 Spring Conference of KOSES and International Sensibility Ergonomics Symposium
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• pp.301-305
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• 2000

The present study is part of the Special Research Project for the Construction of a Kansei Sensory Evaluation Model that is currently underway at the University of Tsukuba. In this study, a robot was operated by remote control at an actual art museum as part of a preliminary experiment. The results obtained therefrom were used to consider how people might view exhibits. In a previous study, a standard lens and s wide-angle lens were used to analyze differences in sensory-based movements, while VRML was used to analyze differences in these movements between a virtual and an actual museum. In the present study, the time delay in remote operation, which is currently unavoidable, placed some restrictions on the degree of freedom with which exhibits could be viewed, but it was apparent that sensory evaluation could be possible depending on the search behavior and viewing time. Furthermore specific viewing behaviors using the robot were observed, suggesting that new Kansei sensory perceptions were derived from these behaviors.