• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2011.10a
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• pp.723-724
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• 2011

• Korean Journal of Optics and Photonics
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• v.20 no.1
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• pp.6-15
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• 2009

A mobile phone camera consisting of two aspheric lenses is designed, and stray light distribution on the image plane is analyzed. We assume that most of the incident light is absorbed on the inner surfaces of the lens barrel and spacers, only a small fraction of the light is scattered uniformly. Assuming that 10% of the incident light is scattered on the barrel and spacers, the maximum value of stray light is 7.1% of the ideal image intensity. The result of analysis shows that stray light originated mostly from internal reflection on the ribs. The contributions of scattering by the barrel and spacers are relatively small. To reduce the internal reflection, thin absorbing plates are inserted between lenses, and the shapes of spacers are modified. After the redesigning of the lens barrel, the maximum value of stray light is reduced to 1.1% of the ideal image intensity.

• Journal of Korean Ophthalmic Optics Society
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• v.14 no.4
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• pp.39-44
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• 2009

Purpose: To design a mini optical system photographing the iris, which is used in the iridology. Methods: We designed a mini optical system photographing the iris by using the Sigma 2000 design program. Results: We designed a mini optical system photographing the iris, which is suitable in the CCD using a micro actuator for auto-focusing, of which characteristics have the TCL of 30 mm, a magnification of -0.65, about 8.0 mm distance from the 1st lens to the last lens, the max barrel diameter of 11 mm, and about 1 mm of the effective stop diameter. Also the resolution line width of this system is characterised by 92 lps/mm at the 30% MTF value criterion. Conclusions: By designing an optical system of which characteristics have the TCL of 30 mm, about 8.0 mm distance from the 1st lens to the last lens, the max barrel diameter of 11 mm, and the resolution line width of $5.4{\mu}m$ at the 30% MTF value criterion, we could miniaturize the iris photographing optical system.

• The Bulletin of The Korean Astronomical Society
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• v.41 no.2
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• pp.52.3-53
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• 2016

일반적으로 사용되는 소구경 망원경은 경통에 의한 차폐로 인해 내부 구조를 보기 쉽지 않으므로, 망원경 광학계를 이해하기에는 적합하지 않다. 본 연구에서는 최소한의 배플 만을 사용하여 경통이 없는 구조의 개방형 망원경을 설계 및 제작하였다. 개발된 변환식 반사망원경 키트(TRT Kit, Transformable Reflecting Telescope Kit)는 부경 모듈을 교체하는 방식만으로 뉴턴식 망원경(Newtonian Telescope), 카세그레인식 망원경(Cassegrain Telescope), 그리고 그레고리식 망원경(Gregorian Telescope)으로 변형하는 것이 가능하다. 주경, 부경을 비롯한 망원경의 모든 부분은 사용자가 직접조립할 수 있도록 모듈화(Modularization) 하였다. 또한 부경에 부착된 슬라이딩 장치 및 리니어 스테이지(Linear Stage)는 망원경의 초점을 정밀하게 맞출 수 있도록 설계하였다. TRT Kit를 이용하여 학생들은 세 가지 형태의 망원경 광학계를 직접 조립하고 그 구조 및 성능을 비교해 볼 수 있으며, 광축 정렬, 정밀 초점 조절 과정을 통해 기본적인 광학계의 원리를 이해 할 수 있다.

• Journal of the Korean Wood Science and Technology
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• v.36 no.3
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• pp.17-23
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• 2008

The purpose of this study is to estimate the shrinkage of wood by LV-SEM (Low-Vacuum Scanning Electron Microscope) which can observe wetted wood sample. The shrinkage of small sample specimen by the dehumidification in the specimen chamber was investigated and compared with that of normal wood specimen. The observation of cross sectional surface of wood from wetted condition to dried condition can be achieved in about twenty minutes by means of the dehumidification in the specimen chamber of LV-SEM. The volumetric shrinkage of earlywood was almost the same as that of latewood. The shrinkage of SEM observation specimen was similar to that of normal wood specimen. From the correlation of the shrinkages between SEM observation specimen and normal wood specimen, it is surmised that the shrinkage of wood is more strictly dominated by shrinkage of latewood than that of earlywood.

• Korean Journal of Computational Design and Engineering
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• v.5 no.1
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• pp.1-11
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• 2000

The purpose of Computer Aided Design is to design good products as quickly as possible. To do this, it is important to reuse the old designs and build on them. Most engineering designers, therefore. hale studied methods for reusing old designs, and the results of their study hale been applied to new designs Unfortunately, this only involves reuse of geometric data without design knowledge. If they can design products with the geometric data, including design knowledge, of the old designed and share them through the Internet, design efficiency will be improved. In other words, one way to improve designer's productivity is to share design information that includes knowledge and scattered data across design offices. This paper introduces a shared design environment with distributed knowledge-base. A product design environment based on distributed knowledge-base is proposed, which integrates the CORBA, OLE and WWW as the network architecture, a 3D CAD system, and an expert system shell. A design example of the lens barrel of a projection television is implemented to verify the idea.

• Design & Manufacturing
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• v.2 no.3
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• pp.10-15
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• 2008

Recently, mobile-phone with camera module has an absolute majority in the released mobile-phones. For this trend, High precision of the plastic subminiature barrel which is the core part is needed significantly because the camera module of mobile-phone must have high performance. Therefore, Structural stability of the injection mold for plastic subminiature barrel has to be guaranteed. In this paper, structural analysis of injection mold for plastic subminiature barrel is performed. Finally, the deformation trend and stability of injection mold core are analyzed.

• The Bulletin of The Korean Astronomical Society
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• v.37 no.2
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• pp.223.1-223.1
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• 2012

우주물체 전자광학 감시체계(OWL: Optical Wide-field Patrol)는 지구상에서 빠르게 이동하는 우주물체를 신속하고 정확하게 관측할 수 있는 광학 감시체계이다. 이 체계의 임무를 완수하기 위한 광학계는 약 2도 이상의 광시야, 충분한 광량 확보를 위해 직경 500 mm 이상의 주반사경(primary mirror), 광학적 능률향상을 위한 25% 이상의 투과율, 운반 및 진동에 의한 영상성능 저하를 보정하기 위한 부반사경 구동기능, 빠른 경통 회전속도에 의한 광학 및 광기구 구조물의 안전성 확보를 위한 작은 F-수 확보 등 주요 요구조건을 만족해야 한다. 본 논문에서는 OWL 광학계의 요구조건을 만족하는 광학계의 광학 및 광기구 설계 등 개발현황을 소개하고자 한다.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.30 no.9 s.252
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• pp.1166-1172
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• 2006

This paper describes an alignment method of the ion column which is used for a focused-ion-beam machining system. The alignment parameters for mechanical and electrical components are introduced, and also sample images are used for evaluating the experiments. The experimental results show that geometrical positions of mechanical components have an influence on the quality of emitted ion beam. In addition, we can successfully align the traveling axis of ions by using mechanical and electrical methods.

• Journal of Korean Ophthalmic Optics Society
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• v.18 no.4
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• pp.509-517
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• 2013

Purpose: The purpose of this study is developing the 2.6 ${\times}$ optical scope with a Abbe-K$\ddot{o}$nig prism. Methods: First, considering the size of the effective aperture and the focal length of the objective lens, we designed an Abbe-K$\ddot{o}$nig prism. Next, we calculated the optical and geometric distances of Abbe-K$\ddot{o}$nig prism designed in this way. After allocating the focal length of the objective lens and the eyepiece lens so as to satisfy the magnification and optical effective distance of the entire system by using this calculation result, we completed the entire system by optimizing this optical system. Results: We were able to complete the optical scope of about 2.6 ${\times}$ magnification by designing an objective lens with a focal length of 63.13 mm which was composed of two pieces, an eyepiece with a focal length of 24.3 mm which was composed of four pieces, and an Abbe-K$\ddot{o}$nig prism with a face length 11.5 mm. Conclusions: We designed and fabricated an optical scope with 2.6 ${\times}$ magnification employing an Abbe-K$\ddot{o}$nig prism. Then, this system became the compacted optical system with a barrel diameter of 31 mm, characterized by an effective aperture of 12.0 mm and an effective optical barrel length of 103 mm and a resolution of 200 cycles/rad at 50% MTF criterion within the half viewing field angle of $6.42^{\circ}$.