• Journal of the Korea Institute of Information and Communication Engineering
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• v.12 no.8
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• pp.1377-1383
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• 2008

Parameterization of a 3D triangular mesh is a fundamental problem in various applications of geometric modeling and computer graphics. There are two major paradigms in mesh parameterization: energy functional minimization and the convex combination approach. In general, the convex combination approach is wifely used because of simple concept and one-to-one mapping. However, the approach has some problems such as high distortion near the boundary and time complexity. Moreover, the stability of the linear system may not be preserved according to the geometric information of the mesh. In this paper, we present an extension of the convex combination approach based on the mean value coordinates, which resolves the drawbacks of the convex combination approach. This may be a more practical solution because it is able to generate a stable linear system in a short time.

• Proceedings of the Korea Information Processing Society Conference
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• 2011.04a
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• pp.526-529
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• 2011

최근 각광 받고 있는 멀티 터치 인터랙션 시스템에서 기존의 디스플레이 방식인 벽면 디스플레이 방식의 네모난 형태의 디스플레이 방식이 아닌 볼록형(Convex) 불규칙 디스플레이 방식으로 산 모양의 디오라마 형태의 디스플레이에서 멀티 터치 인터랙션이 가능한 시스템을 제안한다. 먼저 볼록형 불규칙 표면의 산 디오라마를 제작을 하고 후면 투영 방식으로 프로젝터 영상을 산 디오라마 표면을 대상으로 디스플레이 하고 영상 분석 모듈을 통하여 터치 인터랙션 좌표 정보를 분석한다. 분석된 터치 인터랙션 좌표는 3D 좌표로 변환하고 디스플레이 모듈에 보내면 디스플레이 모듈에서는 인터랙션 메타포로 분석하고 결과를 콘텐츠에 실행시킴으로써 볼록형 불규칙 표면의 산 디오라마에서 멀티 터치 인터랙션에 따른 결과를 사용자가 체감 할 수 있도록 하였다. 본 시스템은 향후 다양한 디오라마 형태로 제작하여 목적에 맞는 전시 시스템으로의 디바이스나 체감형 아케이드 게임 디바이스로 활용이 가능할 것이다.

• Korean journal of applied entomology
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• v.52 no.4
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• pp.415-425
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• 2013

The yellow tea thrips, Scirtothrips dorsalis (Thysanoptera: Thripidae), has been regarded as a minor pest on citrus on Jeju Island. However, the damage of yellow tea thrips has gradually increased since 2007. This study was conducted to develop a forecasting model for generation peak time of S. dorsalis by using degree-days. Simple linear regression analysis was applied to determine the relationship between the generation number (x, dependent variable) and degree-days (y, independent variable). As a result, two regression models were established: citrus-based model (y = 310.9x + 69.0, $r^2$=0.99) and green tea-based model (y = 285.7x + 84.1, $r^2$=0.99). The models was fitted by independent data sets obtained from 2013 and evaluated using the technique of RSS (residual sum of square) and ${\chi}^2$-test. The green tea based-model showed a good fitting ability. The discrepancy between model outputs and actual data, and the practical application of models were discussed.

• 대한공업교육학회지
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• v.43 no.1
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• pp.94-113
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• 2018

The purpose of this study is to develop a using various convex lenses 'VR glasses' instructional materials for area of communication technology of the 2015 Revision Curriculum in middle school. This study was progressed depend on ADDIE model. In the analysis step, a necessity of developing the instructional materials was confirmed through social needs and leaner's needs and literature researches were reviewed about the 2015 Revision Curriculum and virtual reality and confirmed the area of communication technology related to VR glasses. The communication process of information was selected as a communication technology area related to VR glass. In the design step, Based on the analysis stage, instructional objectives were set and instructional method and medium were selected. In the development step was developed instructional materials, what are teaching-learning guidance, power-point presentations, the paper for group learning activities, Individual portfolio, and using various convex lenses VR glasses example. As a result of 'VR glasses' using various convex lenses, the viewing angle was enlarged when the diameter of the convex lens was large, but it was difficult to quantify it. In the implementation step, the instructional materials developed for middle school students was applied. In the evaluation step, instructional materials were modified and improved through a students evaluation, experts evaluation.

• Korean Journal of Optics and Photonics
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• v.32 no.6
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• pp.314-322
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• 2021

A reflecting telescope consists of a concave primary mirror and a convex secondary mirror. The primary mirror is easy to measure, because it converges the beam from an interferometer, while the secondary mirror diverges the beam and so is not easy to measure, even though it is smaller than the primary mirror. In addition, the Korsch-type telescope uses the central area of the secondary mirror, so that the entire area of the secondary mirror needs to be measured, which the classical Hindle test cannot do. In this paper, we propose a double-stitching method that combines two separate area measurements: the annular area, measured using the Hindle stitching method, and the central area, measured using a spherical wave from the interferometer. We test the surface error of a convex asphere that is 202 mm in diameter, with 499 mm for its radius of curvature and -4.613 for its conic constant. The surface error is calculated to be 19.5±1.3 nm rms, which is only 0.7 nm rms different from the commercial stitching interferometer, ASI. Also, the two results show a similar 45° astigmatism aberration. Therefore, our proposed method is found to be valuable for testing the whole area of a convex asphere.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 1991.10a
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• pp.343-343
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• 1991

• Proceedings of the Korean Society of Computer Information Conference
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• 2009.01a
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• pp.177-180
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• 2009

볼록거울을 사용하여 CCTV시스템을 만들면 카메라 수를 줄이는 효과가 있다. 이 경우 볼록거울 영상은 휜 영상이므로 평면영상처럼 변환해야 한다. 이 경우에, 중앙에 비추인 영상은 평면 영상으로 변환 후에도 왜곡이 거의 없지만 거울의 테두리 부근에서 얻은 영상을 변환하면 왜곡이 심하게 나타나서 영상 내의 물체를 식별하기가 어려워진다. 렌즈의 초점이 거울의 중심부에 맞춰져 있기 때문에 변에 있는 영상은 픽셀들 사이에 겹침이 일어나기 때문이다. 본 논문에서는 픽셀들 사이의 광학적 겹침을 극복하기 위해 확산 방정식의 후진대입 해를 사용하였다. 결과를 분석하기 위해 PSNR값을 조사하였더니 제안된 방법은 N. Moayeri의 방법보다 4 dB 정도 개선되었다.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.37 no.2
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• pp.1-7
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• 2000

In this paper, an adaptive control law for nonlinear systems represented by input-output models are proposed under the assumption that unknown system parameters are in a known compact and convex set. Contrary to the previous results, the compact and convex set is not restricted to a ball whose center is at the origin or convex hypercube. It is proven that the proposed parameter update rule produces a sequence of parameters which reside in the set and guarantees that the position, velocity, and acceleration error converges to zero as time goes to infinity. This theoretical result was justified through simulations.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.27 no.6
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• pp.1041-1049
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• 2003

In this paper, a new local two-point approximation method which is based on the exponential intervening variable is proposed. This new algorithm, called the Two-Point Convex Approximation(TPCA), use the function and design sensitivity information from the current and previous design points of the sequential approximate optimization to generate a sequence of convex, separable subproblems. This paper describes the derivation of the parameters associated with the approximation and the numerical solution procedure. In order to show the numerical performance of the proposed method, a sequential approximate optimizer is developed and applied to solve several typical design problems. These optimization results are compared with those of other optimizers. Numerical results obtained from the test examples demonstrate the effectiveness of the proposed method.

• The Journal of the Acoustical Society of Korea
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• v.12 no.6
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• pp.53-61
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• 1993

이 논문은 접은 도체박판의 단순한 구조가 전자유도형 변환기 역할을 한다는 것을 기술하고 있다. Endoh 등은 볼록한 나선코일과 동박판으로 구성된 볼록한 방사면 모양을 한 전자유도형 변환기가 시간적으로 짧은 충격파를 발생할 수 있기 때문에 뚜렷한 초음파 영상을 얻을 목적으로 Eisenmenger에 이어 전자유도형 EMAT를 보고한 바 있다. 여기서는 코일이 없는 EMAT를 소개한다. 이것은 두께 0.05mm, 폭 5cm 길이 임의의 동박판으로 구성되며 동박판은 절연도료를 칠한 종이로 절연되고 접어서 견고하게 밀착시키며, 여러번 접는 경우는 손부채처럼 접는 방향은 교대로 반대방향으로 접는다. 그리고는 엷은 고무판을 표면에 밀착시키고 연변을 실리콘 충전제등으로 고정시키거나, polyester molding을 하여 표면을 concave형으로 하여 완성하였다. 완성된 EMAT들은 수조에서 축전기방전방식으로 실험을 하였으나 EMAT에서 발생되는 으파의 진폭은 접는 회수에 비례하였으녀, 단접형 EMAT보다 다접형 EMAT의 발생음파가 보다 강력하였다. Concave형 EMAT의 음속은 예견한 바와 같이 잘 집속되었다. 그러나 평판형의 경우는 지향성은 100도로서 넓은 지향각을 나타내었다. 2μF, 600Volt의 축전기 방전에 의한 집속형 concave EMAT를 여기시키기 위한 축전기의 용량이 작을수록 대역폭은 더욱 넓었다.