• 한국전기전자재료학회논문지
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• 제21권1호
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• pp.35-43
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• 2008

Aviation obstacle lights including controller for the safe night aviation service have applied to high voltage transmission line of which height is from $60{\sim}180 m$, Fresnel lens made by Augustine Fresnel have been applied to light houses, These Fresnel lens were applied to aviation obstacle lights and have been universally used, It was reported that Fresnel lens for aviation obstacle light was used in the first place in Korea in 1987, LEDs have recently been applied to aviation obstacle lights, So, the optimum physical design is essential to the design of aviation obstacle light. In this study, optical and three dimensional modeling of LED module and globe lens were performed, And thermal analysis due to LED thermal source and service thermal condition in high voltage transmission line was performed and was analyzed comparing with experiments, The optimum design process of medium intensity LED aviation obstacle lights was constructed with three dimensional modeling, thermal analysis, and thermal experimental technique.

• Current Optics and Photonics
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• 제1권5호
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• pp.538-543
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• 2017

Progressive addition lenses (PAL) have very wide application in the modern glasses market. The unique progressive surface can make a lens have progressive refractive power, which can meet the human eye's different needs for distance-vision and near-vision. According to the national glasses fabrication standard, the difference between actual optical power after fabrication and nominal design value should be less than 0.1D over the lens effective area. The optical power distribution of PAL is determined directly by the surface. Consequently, the surface processing accuracy requirement is proposed. Beginning from the surface expressions of progressive addition lenses, the relationship equations between the surface sag and optical power distribution are derived. They are demonstrated through tolerance analysis and test of an example progressive addition lens with addition of 2.09D (5.46D-7.55D). The example addition surface is fabricated under given accuracy by a single-point diamond ultra-precision machine. The optical power of the PAL example is tested with a focal-meter after fabrication. The optical power addition difference between test result and design nominal value is 0.09D, which is less than 0.1D. The derived relationship between the surface error and optical power is verified from the PAL example simulation and test result. It can provide theoretical tolerance analysis proof for the PAL surface fabricating process.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2006년도 추계학술대회논문집
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• pp.463-463
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• 2006

Nowadays, subminiature lens actuators are being developed with the demand of AF lens for high performance of the mobile phone camera. Though the VCM is the current, development of new types of actuators are needed due to the structural problem and etc.. A new type of actuator for AF lens using Dielectric Elastomer Electroactive Polymer(EAP) is proposed in this paper, DE EAP has advantages in its weight, ease of fabrication and low power consumption. The mathematical model is obtained by Hamilton's principle and verified by finite element analysis and experiments. The controller is designed and evaluated by experiments.

• 한국인쇄학회지
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• 제20권1호
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• pp.113-122
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• 2002

We designed the illumination optical system to use Fresnel lens which is the most general type of large aperture system. The normal construction of Fresnel lens is a thin molded piece of material, usually some kind of plastic, with one side flat and the other comprising a series of concentric segments each angled in a way to provide for optimum focusing for a pair of conjugate points. The 155 mm Marine Signal Lantern is the approved for use on buoys and a maximum omnidirectional range of 8 nmi, can be obtained with standard 12V equipment, respectively. Finally, Fresnel lens with 155 mm diameter was designed and evaluated. Also, we re-designed groove "out" of Fresnel lens and compared results of groove "in" type with groove "out" type. According to the results, Fresnel lens is obtained best optical results when grooved side faces the longer conjugate.de faces the longer conjugate.

• 조명전기설비학회논문지
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• 제27권8호
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• pp.1-8
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• 2013

The study carried out in this dissertation focuses on the lens structure design and the light distribution for LED safety luminaires using COB type LED module. Lens structures for LED lights has been designed 1) to induce light diffusion by dual process of internal reflection and refraction, 2) to minimize the inherent LED lights' glittering, and 3) to have uniform brightness. The lens designed with the proposed structures function as diffusers for the divergence of the LED lights so that they form a wide angle of view and adjust the light distribution. We designed of lens with stable uniformity factor and average roughness using aspheric optics property. Finally we made the analysis data of the simulated data.

• 한국광학회지
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• 제13권4호
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• pp.275-282
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• 2002

2매 접합렌즈와 단렌즈로 구성된 2군 렌즈계의 구면수차, 코마, 종색수차 보정을 위한 3차수차 전개식을 얇은렌즈 근사를 이용하여 해석적으로 유도하였다. 유도된 3차수차 전개식은 telephoto렌즈계의 설계에 적용되었다. 초기설계에서 광학유리 조합은crown-flint-crown조합과 flint-crown-flint 조합에 관하여 조사하였다. Crown-flint-crown조합의 경우 2가지 형태의 achromatic aplanat 존재하였다. Flint-crown-flint조합의 경우에서도 2종류의 해가 존재하였으나, 해의 형태가 유용하지 못하였다.

• 한국재료학회지
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• 제29권12호
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• pp.735-740
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• 2019

The purpose of this study is to fabricate an ophthalmic lens by copolymerizing two types of carbon nanotubes and hydrophilic hydrogel lens materials, and to investigate its application as an ophthalmic lens material by analyzing its physical properties and antimicrobial effect. For polymerization, HEMA (2-hydroxyethyl methacrylate), EGDMA (ethylene glycol dimethacrylate), a crosslinking agent, and AIBN (azobisisobutyronitrile), an initiator, are used as a basic combination, and a single-walled carbon nanotube and a single-walled, carboxylic-acid-functionalized carbon nanotube are used as additives. To analyze the physical properties, the water content, refractive index, breaking strength, and antimicrobial effect of the fabricated lenses are measured. The fabricated lenses satisfies all the basic properties of the basic hydrogel ophthalmic lens. The water content increases with increasing amount of additive and decreases with addition of 0.2 % ratio of nanoparticles. The refractive index is inversely proportional to the water content result. As a result of the antimicrobial test of the fabricated lens, the addition of carbon nanotubes shows an excellent antimicrobial effect. Therefore, it is considered that the fabricated lens can be applied as a functional material for basic ophthalmic hydrogel lenses.

• 한국기계가공학회지
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• 제18권11호
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• pp.18-23
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• 2019

The oil immersion method can be used to create objective lenses with long working distances without sacrificing the focusing resolution for laser processing. In this study, a space in which air or oil can be filled was formed in the middle of a lens for analyzing the optical properties of a liquid-oil immersion lens. As the refractive media, air and oils of different refractive index values (1.2 and 1.5, respectively) were used. A simulation was conducted in the ZEMAX software environment using the ray-tracing technique, and the performance of the oil immersion lens was verified by determining its image distortion and focal length (FL) in each medium. In the case of air, the calculated FL was 0.813 mm, whereas the imaged FLs were 1.594 mm and 8.126 mm when the refraction indices were 1.2 and 1.5, respectively. The FL of an oil immersion lens could be increased considerably. In terms of image distortion, the oil immersion lens exhibited little distortion at the center in all cases, but different degrees of image distortion were observed at different points away from the center depending on the refraction index degree.

• 한국안광학회지
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• 제18권3호
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• pp.241-246
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• 2013

목적: 본 연구에서는 프리폼 누진렌즈와 일반 누진렌즈를 착용 하였을 때 원거리 대비감도에 미치는 영향을 비교 분석 하였다. 방법: 안질환이 없는 성인 20명을 대상으로 원거리 대비감도 검사를 실시하였고 5단계의 공간 주파수를 갖는 F.A.C.T.(Stereo Optical, USA)를 이용하였다. 우안, 좌안, 양안 순서로 프리폼 누진렌즈와 일반누진렌즈 대비감도를 측정하였다. 결과: 우안/좌안/양안 대비감도 검사 값이 A(1.5 cpd) 공간주파수에서는 일반 누진렌즈에 비교하여 프리폼 누진렌즈가 16%/17%/11%, B(3 cpd) 공간주파수에서는 11%/5%/5%, C(6 cpd) 공간주파수에서는 6%/6%/9%, D(12 cpd) 공간주파수에서는 19%/16%/13%, E(18 cpd) 공간주파수에서는 4%/3%/18% 높았다. 결론: 원거리 대비감도의 모든 공간주파수 영역에서 프리폼 누진렌즈가 일반 누진렌즈보다 측정값이 높게 측정되었다.

• 응용통계연구
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• 제35권2호
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• pp.265-283
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• 2022

사용자들의 영화정보를 기록한 MovieLens 데이터는 추천 시스템 연구에서 아이디어를 탐색하고 검증하는데 상당한 가치가 있는 데이터로, 기존 데이터 분할 및 군집화 알고리즘을 사용하여 사용자 평점 데이터를 기반으로 항목 집합을 분할하는 연구 등에 사용되는 데이터이다. 본 논문에서는 기존 연구에서 대표적으로 사용되었던 영화 평점 데이터와 영화 장르 데이터를 통해 사용자의 장르 선호도를 예측하여 선호도 패턴을 기반으로 사용자를 군집화(clustering)하고, 유의미한 정보를 얻는 연구를 진행하였다. MovieLens 데이터는 영화의 전체 개수에 비해 사용자별 평균 영화 평점 수가 낮아 결측 비율이 높다. 이러한 이유로 기존의 군집화 방법을 적용하는 데 한계가 존재한다. 본 논문에서는 MovieLens 데이터 특성에 모티브를 얻어 쌍별 규합 벌점함수(pairwise fused penalty)를 활용한 볼록 군집화(convex clustering) 기반의 방법을 제안한다. 특히 결측치 대체(missing imputation)도 동시에 해결하는 최적화 문제를 통해 기존의 군집화 분석과 차별화하였다. 군집화는 반복 알고리즘인 ADMM을 통해 제안하는 최적화 문제를 풀어 진행한다. 또한 시뮬레이션과 MovieLens 데이터 적용을 통해 제안하는 군집화 방법이 기존의 방법보다 노이즈 및 이상치에 상대적으로 민감하지 않은 것으로 보인다.