• Proceedings of the KAIS Fall Conference
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• 2008.05a
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• pp.43-45
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• 2008

박막 제작공정은 반도체 제작 공정, 고정밀도의 하드디스크 및 레이저 디스크 기술, LCD/P에 DML평판 디스크 플레이어 제작 공정에 있어 중요한 기술이다. 더욱이, 이 공정은 이동 전화 커버의 증착 및 전자 차폐의 일반기술, 램프의 반사판, 화장품 용기, 몇몇 상품에 있어 카메라 렌즈의 광학 표면 코팅과 코팅 필름 제작에 사용된다. 본 연구의 주요목적은 반도체 제작 공정과 많은 산업 분야에서 기본 재료로 사용되는 전영저항의 개발에 있다. 개발 공정은 다음과 같다. 전자빔이 최상의 진공 분위기에서 텅스텐 필라멘트의 열에 의해 방출된다. 그때 전자는 높은 전압에서 가속화된다. 전자들은 반대 재료에 충돌되고, 반대편 재료는 발생 열에 의해 코팅된다. 1차년도 연구목적은 고성능 전열 저항체 개발을 위한 지름 당 필라멘트 선의 기계적 특성을 조사하고 CAE 해석을 수행하며, 2차 년도에는 대량 생산 라인 구축을 위한 자동검사 라인 개발에 초점이 맞추어져 있다. 만일, 본 연구를 통해 전열 저항체가 개발된다면, 그 제품은 고효율, 외국제품 대비 가격 경쟁력을 가지므로 제품 경쟁력을 가질 수 있을 것으로 생각된다.

• Korean Journal of Optics and Photonics
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• v.3 no.3
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• pp.155-160
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• 1992

1)iscussed in this paper are the effects of phase modulation on the line spread functions (LSF) and MTFs of ;I binocular objective system. The binocular objective lens is made in Korea. It has rotationally symmetric aberrations. The LSFs and MTFs are measured experimentally. The phase modulation is carried out by applying phase retardation n on the aperture. The area where the phase is not retarded presents a double annular type. The OTF curves of phase modulated aperture are compared with that of unmodulated aperture. The comparison shows that there is the aberration compensation effect in aberration loaded system. Therefore the performance of many optical system can be improved without any loss of light energy by properly modulating the phase on the aperture.

• Korean Journal of Optics and Photonics
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• v.31 no.1
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• pp.26-30
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• 2020

First, if we want to design and construct a robotic camera, we need to understand the parallax errors between adjacent images, caused by rotation and movement of the robotic camera system. In this paper, we try to derive the mathematical formulation of parallax error and connect it to a conventional lens system, to obtain a useful, generalized, analytic algebraic expression for the parallax error. Utilizing this expression, we can structurally design a robotic camera, and study the Google ART camera as an example of a robotic camera.

• Design & Manufacturing
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• v.6 no.1
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• pp.12-17
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• 2012

In order to produce high-quality optical components, aspheric lenses have been widely applied in recent years. An aspheric lens consists of aspheric surfaces instead of spherical ones, which causes difficulty in the design process as well as the manufacturing procedure. Although injection molding is widely used to fabricate optical lenses owing to its high productivity, there remains lots of difficulty to determine appropriate mold design factors and injection molding parameters. In the injection molding fields, computer simulation has been effectively applied to analyze processes based on the shell analysis so far. Considering the geometry of optical lenses, a full-3d simulation based on solid elements has been reported as a reliable approach. The present work covers three-dimensional injection molding simulation and relevant deformation analysis of an injection molded plastic lens based on 3d solid elements. Numerical analyses have been applied to the injection molding processes of three aspheric lenses for an image sensing module of a mobile phone. The reliability of the proposed approach has been verified in comparison with the experimental results.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.11a
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• pp.743-748
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• 2007

This paper describes a lens transmissive type tilting actuator for a projection TV. An electromagnetic analysis and a structural analysis of the tilting actuator system is necessary to design a tilting actuator for a projection TV. The tilting actuator is composed a permanent magnet, coil and yoke as the electromagnetic components and it needs a driving hinge part as the mechanical component. The design of the tilting actuator for the projection TV is performed by the following procedure. Firstly, a magnetic flux density of the tilting actuator system is analyzed by a mathematical theory and an electromagnetic FEM. Secondary, a magnetic circuit method is used to determine tilting force. Thirdly, the structural FEM is carried out with an FE model of a lens-transmissive type tilting actuator and then the prototype of the model is manufactured. The characteristic of the prototype is experimentally observed. Finally, a design for a new hinge configuration is suggested for better performance.

• Proceedings of the KSME Conference
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• 2007.05a
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• pp.1288-1293
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• 2007

The present study covers the design and analysis of a thermionic scanning electron microscope (SEM) column. The SEM column contains an electron optical system in which electrons are emitted and moved to form a focused beam, and this generates secondary electrons from the specimen surfaces, eventually making an image. The electron optical system mainly consists of a thermionic electron gun as the beam source, the lens system, the electron control unit, and the vacuum unit. In the design process, the dimension and capacity of the SEM components need to be optimally determined with the aid of finite element analyses. Considering the geometry of the filament, a three-dimensional (3D) finite element analysis is utilized. Through the analysis, the beam emission characteristics and relevant trajectories are predicted from which a systematic design of the electron optical system is enabled. The validity of the proposed 3D analysis is also discussed by comparing the directional beam spot radius. As a result, a prototype of a thermionic SEM is successfully developed with a relatively short time and low investment costs, which proves the adoptability of the proposed 3D analysis.

• Journal of the Korean Data and Information Science Society
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• v.24 no.6
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• pp.1341-1348
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• 2013

To solve the classification problems, various data mining techniques have been applied to database marketing, credit scoring and market forecasting. In this paper, we compare various techniques such as bagging, boosting, LASSO, random forest and support vector machine with the daily lens transaction data. The classical techniques-decision tree, logistic regression-are used too. The experiment shows that the random forest has a little smaller misclassification rate and standard error than those of other methods. The performance of the SVM is good in the sense of misclassfication rate and bad in the sense of standard error. Taking the model interpretation and computing time into consideration, we conclude that the LASSO gives the best result.

• Journal of Korean Ophthalmic Optics Society
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• v.12 no.4
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• pp.119-125
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• 2007

The aim of the present study was to compare the contrast sensitivity of soft contact lens wearers, spectacle wearers or emmetropia. Seventy myopic eyes and thirty emmetropic eyes aged 19 to 26 years were collected. The myopic group included 48 eyes corrected with spectacle lenses and 22 eyes of them corrected with contact lenses, too: all had corrected vision acuity of 20/20 or better. Spatial contrast sensitivity was measured using the OPTEC 6500 contrast sensitivity view-in tester included the EyeView　 Functional Vision Analysis software at photopic or mesoopic condition. There was no significant difference in contrast sensitivity between spectacle lenses and emmetropes. Myopes corrected with soft contact lenses showed statistical sensitivity losses at 1.5, 12 cycle/degree spatial frequencies. In conclusion, our findings suggest that loss of contrast sensitivity in soft contact lens wearers might be interpreted as evidence for corneal disruption before corneal pathological events occur in contact lens wearers. Contrast sensitivity testing appears to be a useful method for evaluating soft contact lenses.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.44 no.2
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• pp.156-164
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• 2016

Qualification model(QM) of main payloads including concentrating photovoltaic system using fresnel lens, heating wire cutting type shockless holding and release mechanism, and MEMS-based solid propellant thruster have been developed for the STEP Cube Lab.(Cube Laboratory for Space Technology Experimental Project), which is a pico-class satellite for verification of core space technologies. In this study, we have verified structural safety and functionality of the developed payloads under a qualification temperature range through the QM thermal vacuum test. Additionally, a reliability of thermal model of the payloads has been confirmed by performing a thermal correlation based on the thermal balance test results.

• Water for future
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• v.22 no.1
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• pp.81-90
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• 1989

A numerical simulation technique of three-dimensional finite difference model is developed to study the groundwater flow system in Dejima, an upland area which faces Kasumigaura Lake. For general perspectives of the groundwater flow system, a steady state three-dimensinal model is simulated. For the sedimentary mud formations which are found in the representative formation, three situations where the horizontal permeability is equal to 10 times and 100 times of the vertical one. The finite difference grid used in the simulation has 60$\times$50$\times$30=90,000 nodes. A converged solution with a tolerance of 0.001 meter of hydraulic head is set. Having determined the flow net by using a steady state three-dimensional model, the results for the three cases of hydraulic conductivity are compared with the results of the tracer methods (Bae and Kayane, 1987). With the aid of four representative vertical cross-sections, groundwater flow systems in the study area are assumed. The results of these are reasonally good comparable with the results of the basin yield and thd recharge-discharge distribution 8.