• Journal of the Korean Society for Precision Engineering
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• v.32 no.11
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• pp.961-968
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• 2015

This study aims to develop an efficient mold structure for the injection molding of a subminiature lens, using shell-type runners instead of traditional cylindrical runners. While the shell runner has the advantage of shorter cooling time due to its thinner geometry, this smaller thickness causes an increase in injection pressure. In this study, the design of the shell runner was modified to contain multiple holes for the purpose of reducing injection pressure. Numerical analyses were performed for shell runners of various hole-shapes, and the resulting filling and cooling characteristics were discussed; the rhombic hole showed the best result for both filling and cooling characteristics. Subsequently, injection molding experiments were performed using an injection mold fabricated based on the rhombic design. The lens parts were successfully molded with highly-reduced cycle time and without degradation of part quality.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.20 no.6
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• pp.114-120
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• 2021

This study is focused on the root mean square and peak-to-valley based on the injection conditions of the f-theta lens, one of the main components of laser printers and laser scanning systems. The f-theta lens of an aspherical plastic lens requires ultra-preaction. Injection molding is typically used for the mass production of aspherical plastic lenses. In the injection-molding method, the resin in the lens shape is filled with the resin after melting the plastic pellets at a constant temperature and then cooled. It is necessary to maintain a uniform injection molding system to produce high-quality lenses. These injection-molding systems are influenced by different factors, such as pressure, speed, temperature, mold, and cooling. It is possible to obtain a lens that exhibits the optical characteristics required to achieve harmony. We investigated the root mean square and peak-to-valley caused by variations in temperature, a critical parameter in the melting and cooling of plastic resins generated inside and outside the injection mold.

• Journal of the Korean Society for Precision Engineering
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• v.22 no.12 s.177
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• pp.100-107
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• 2005

The present work covers a new ray tracing scheme of an injection-molded plastic lens linked with finite element analysis fur injection molding processes. The traditional ray tracing schemes have been based on the assumption that optical property of the lens is homogeneous throughout the entire volume. However, this assumption is quite unrealistic for injection-molded plastic lenses since material properties vary at every point due to injection molding effects. In order to consider non-homogeneous property of a lens, a modified ray tracing method is proposed in connection with finite element analysis of injection molding. Through the analysis of the injection molding process, the distribution of refractive indices can be obtained. This information is then utilized in the proposed ray tracing scheme based on finite element meshes so as to take into account variation of the refractive indices. The effect of mold temperature is also investigated through finite element analysis, and the relevant optical quality is evaluated through the proposed ray tracing simulation.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.38 no.2
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• pp.219-225
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• 2014

An automatic combination and assembly system for phone-camera lens modules was developed. The system enables the assembly of the relative orientation of the individual lenses making up the lens module. Conventional assembly systems assemble a lens module from eight assembly units. The developed system reduces this number to half by combining each lens and a spacer into a single assembly unit. Also, the number of transfer stages for sequential assembly is minimized without increasing the assembly time. Therefore, high productivity and a footprint that is only about 25 % of that of a conventional assembly system can be realized. The system features a modular design to allow it to cope with rapid changes in the market. Only a few components, such as the picker and guide, need to be replaced for changing to a new assembly model.

• Proceedings of the KAIS Fall Conference
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• 2000.10a
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• pp.226-229
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• 2000

일반적으로 안경집은 일회적으로 사용하고 버리는 것이라 생각하는 사람이 많다. 안경집을 주로 생산하고 있는 대동사출금형과의 공동 노력으로 다기능성 안경집을 개발한 것을 소개한다. 일상적인 고정관념을 버리면 편리하고 기능성이 높은 제품을 만들 수 있다는 신념으로 개발한 결과 어린이나 젊은이들이 졸아할 문방구 겸용 안경집을 개발할 수 있었다. 완구는 소비자가 일상적으로 많이 접촉하기 때문에 곰팡이나 세균이 서식하지 않도록 항균 세라믹을 이용하여 항균처리하였다. 또한 상온에서 인체에 이로운 원적외선이 방출될 수 있도록 고안하였다. 단순한 색상의 무료함을 줄이기 위하여 어린이나 젊은이들이 좋아하는 상용화된 캐릭터를 사용하여 제품의 다양화를 꾀하였고, 4개의 조각으로 만들어 어린이들이나 젊은이들이 조립할 수 있도록 하여 흥미를 더할 수 있도록 하였다. 또한 소비자들이 선호하는 색을 알아보기 위하여 기존의 안경집을 활용하여 색상성호도 조사를 실시하였다. 젊은층은 자극적이고 화려한 색깔을 선호하는 한편 기성세대는 무난한 색깔을 선호하였다. 또한 콘택트 렌즈를 착용하는 경우에도 안경을 사용하는 경우가 많다. 이 경우 콘택트 렌즈와 안경을 따로 가지고 다녀야 하는 불편이 있다. 이에 착안하여 안경과 콘택트 렌즈를 겸용으로 사용하는 소비자를 위하여 안경과 콘택트 렌즈를 동시에 담을 수 있는 안경집을 개발(실용신안 출원번호:8928)하였다. 이 고안은 콘택트 렌즈를 안경집에 보관하기 위한 것으로 콘택트렌즈가 식염수에 잠겨 보관된 렌즈캡을 안경집내에 별도로 삽입되는 케이스에 수납하도록 구성하여 안경과 함께 콘택트 렌즈를 보관해 휴대하는 안경집 보관용 콘택트 렌즈 케이스에 관한 것으로 이것의 특징은 뚜껑이 열리고 닫히도록 구성된 안경집에 있어서 뚜껑 안쪽에 거울이 마련되고 뚜껑이 연결되는 선단부 안쪽에 끼움홈과 체결홈이 형성된 체결부를 갖는 안경집과 이것에 결합되는 체결구가 마련되어 개폐되는 커버가 형성된 케이스로 구성된다.로 금형설계 및 제작기간을 단축하고자 한다.ere demonstrated in rats after i.c.v., intraperitoneally and orally administration, respectively. The antiepileptical effects by the combination of compounds from ginseng; were compared with the iuluence of Rg1, Rb1, Rc and with the well known antiepileptical drugs such as carbamazepine, valproic acid. The base for the research is obtained by using the WAG/Rij strain (Luijtelaar, Coenen, Kuznetcova), an excellent genetic model for human generalized absence epilepsy. The improving action of gensinosides was effectively demonstrated on the model of electrical kindling of amygdala of WAG/Rij rats with genetically determined absences, and the influences of ginsenosides on the slow wave discharges have also been being investigated. The different characteristics of a kindling process exerted in the sex-different region of the amygdala and demonstrated that the level of sex steroids and content of neurosteroids in amygdaloid tissue ca

• Korean Journal of Optics and Photonics
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• v.8 no.3
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• pp.189-193
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• 1997

Aspheric pick-up lenses are increasingly used in consumer products such as computer and multimedia, as their mass production has become possible owing to the injection molding process. However still much work needs to be done for more effective manufacture of aspheric lenses, one area of which is the in-line inspection of produced lenses. In this paper, we present a lateral-shearing interferometer that has specially been designed to have a high immunity to external vibration and atmospheric disturbance. The interferometer comprises four prisms. They are directly attached to each other using an immersion oil so that relative sliding motions between the prisms are allowed. Their relative displacement can readily generate necessary lateral-shearing and phase-shifting to determine the wavefront of the beam collimated by the lens under inspection. A special phase-measuring algorithm of arbitrary-bucket is adopted to compensate the phase-shifting error caused by the thickness reduction in the immersion oil. Zernike polynomial fitting has done for determinating quantitative aberration of aspheric pick-up lenses. The interferometer built in this work is robust to external mechanical vibration and atmospheric disturbance so that experimental results show that it has a repeatability of less than λ/100.

• Journal of the Korea Society for Simulation
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• v.23 no.4
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• pp.131-142
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• 2014

Phone camera lens module is assembled with a barrel, multiple lenses, multiple spacers and a shield. The major processes of manufacturing system are injection molding, coating and assembly processes, and each process has multiple machines. In this paper, we introduce a scheduler based on simulation model which can be used for frequent rescheduling problem caused by urgent orders, breaking down of molds and failures of machines. The scheduling algorithm uses heuristic Backward-Forward method, and the objective is to minimize the number of tardy orders.

• Journal of the Korean Society for Precision Engineering
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• v.22 no.6 s.171
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• pp.55-60
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• 2005

This paper has been focused in developing of plastic lens with ultra-precision and low birefringence ability using by injection molding simulation tools. The simulation tools, $3D-Timon^{TM}\;and\;Asu-Mold^{TM}$ were applied to visualize indirectly the flow pattern of melted polymer enter the mould and the simulation results are verified as compared with the experimental results. Birefringence and polarized light generated in injection molding process was also calculated for each injection conditions and compared with .the pictures of experimented optical lens go through the polarized light plates device. A spherical radius of plastic optical lens transcribed from profile of mould core surface was measured to estimate the geometrical accuracy fer the each injection conditions. It is confirmed that the simulation results about flow pattern and polarized light area coincided in experimental results. It is known that increasing in thickness shrinkage at center of lens, the spherical radius is larger from comparing the graph measured spherical radius and the thickness shrinkage at center of lens

• Transactions of the Korean Society of Mechanical Engineers A
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• v.29 no.6 s.237
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• pp.828-834
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• 2005

Recently, injection molded plastic optical products are widely used in many fields, because injection molding process has advantages of low cost and high productivity. However, there remains residual birefringence and residual stresses originated from flow history and differential cooling. The present study focused on developing a technique to measure the birefringence in optical plastic parts using R-G-B separation of white light. The main idea of an analysis comes from the fact that more information can be obtained from the distribution of retardation caused by different wavelengths. A complete system to give the quantitative values of retardation covering high order 2-D birefringence will be demonstrated. Further investigation is under way to improve the accuracy of the system using diodes as light sources.

• Proceedings of the KSME Conference
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• 2004.04a
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• pp.1761-1766
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• 2004

Recently, Plastic optical products are widely used. Injection molding process has advantages of low cost and high productivity. However, it remains a residual birefringence and residual stress by difference cooling. The present study focused on measuring birefringence in optical plastic parts using interference color pattern. The main idea of an analysis comes from chromatic aberration which is caused by difference light wavelengths. As a result, a complete system measuring the high order 2-D birefringence pattern was built. Further investigation is under way to improve the accuracy of birefringence measurement system by diode laser.