• Journal of the Korean Society for Precision Engineering
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• v.27 no.2
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• pp.70-77
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• 2010

This study proposed an auto focusing method for a multi-focus image in assembling lens modules in digital camera phones. A camera module in a camera phone is composed of a lens barrel, an IR glass, a lens mount, a PCB board and aspheric lenses. Alignment among the components is one of the important factors in product quality. Auto-focus is essential to adjust image quality of an IR glass in a lens holder, but there are two focal points in the captured image due to thickness of IR glass. So, sharpness, probability and a scale factor are defined to find desired focus from a multi-focus image. The sharpness is defined as clarity of an image. Probability and a scale factors are calculated using pattern matching with a registered image. The presented algorithm was applied to a lens assembly machine which has 5 axes, two vacuum chucks and an inspection system. The desired focus can be determined on the local maximum of the sharpness, the probability and the scale factor in the experiment.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.21 no.11
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• pp.1036-1042
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• 2011

APR1400 RVI CVAP using the non-prototype category II is being conducted to verify integrity of the RVI design and to secure the CVAP technology. The measurement programs are to confirm vibration analysis results for reactor internals during pre-operational and initial startup testing and to determine the safety margin. One of the important basis for the measurement programs is test acceptance criteria. Therefore, this paper is on establishment of response instrumentation test acceptance criteria for APR1400 RVI CVAP. The established acceptance criteria show that the stress criteria of APR1400 RVI are more conservative values than those of the valid prototype plant(Palo Verde unit 1) and, the displacement criteria of the inner barrel assembly and the upper guide structure were established to 0.03 in and 0.01 in, respectively.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1998.04a
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• pp.582-589
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• 1998

This paper presents the analysis results of ex-core and in-core neutron noise, acceleration signals and pressure fluctuation measured at Ulchin Nuclear Unit 1 & 2 to identify and monitor the reactor internals vibration including fuel motion. A phase separation algorithm developed by authors was applied to the neutron noises to clearly identify the reactor internals vibratory motion. The beam mode frequency of the core support barrel was identified to be 8Hz and the shell mode to be 20Hz. The first frequency of the fuel assembly was also found to be 3Hz, while first two acoustic frequencies of the primary coolant system were 6 and 17.5Hz. By monitoring and analyzing these frequencies periodically, it is possible to diagnose the operating condition of reactor internals and to provide an early detection of faults for the predictive maintenance.

• Proceedings of the KIEE Conference
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• 2000.11d
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• pp.638-640
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• 2000

Reactor Noise is defined as the fluctuations of measured instrumentation signals during full-power operation of reactor which have informations on reactor system dynamics such as neutron kinetics, thermal-hydraulics, and structural dynamics. Reactor noise analyses of ex-core neutron detector internals such as fuel assembly and Core Support Barrel in Nuclear Power Plant. A real time mode separation technique have been developed and applied for the analyses. The analyses data base have been constructed for the continuous monitoring and diagnose of the reactor internals. Detailed design of diagnostic system reactor internal structures using neutron noise(RIDS).

• Journal of the Korea Society for Simulation
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• v.22 no.4
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• pp.83-92
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• 2013

The demand of a camera-lens-module which is installed in mobile phone has been increased explosively as the increase of mobile phone market. Recently, two missions are given to the parts manufacturer of lens module, and they are how to keep the quality of injection moulding process as the increase of resolution, and how to decrease manufacturing cost. In this paper, a simulation study is introduced which is used for developing barrel and shield considering the double-cassette type of mould. At first, the simulation for injection process using Mold Flow$^{TM}$ is applied in the phase of mould design, and mechanical simulation using DPM Assembly$^{TM}$ is applied for collision detection between picking robot and mould. As a result, the productivity increased more than 300%.

• Korean Journal of Optics and Photonics
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• v.32 no.6
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• pp.259-265
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• 2021

Recently, lens manufacturing and assembly technology has greatly improved. However, tight requirements of manufacturing and assembly lead to an increase in cost and manufacturing time, and in some cases the performance of an optical system may deteriorate depending on the operating environment's conditions, such as temperature or vibration. In addition, the use of a compensator is an effective method to reduce sensitivity in an ultra-precision optical system, but in the case of a small lens, such as that in an endoscope, it is difficult to use a compensator due to the size limitation of the lens barrel. Therefore, minimizing lens sensitivity is the most important technology in lens design. For this reason, there have been various attempts to reduce the lens sensitivity, and there is a trend to add functions to reduce the sensitivity in the lens design S/W. In this paper, we introduce a design technology that minimizes lens sensitivity. We first design a lens with quite good performance, then analyze the sensitivity of this lens, make a multi-configuration with high-sensitivity element error, and then reoptimize it. We prove with an example that this design technique is very effective.

• 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.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2014.10a
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• pp.399-401
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• 2014

The comprehensive vibration assessment program(CVAP) of APR+ nuclear power plant(NPP) is classified as non-prototype, category II with Palo Verde NPP as valid prototype. In this paper, CVAP for first plant of APR+ NPP is proposed. The Control Element Assembly(CEA) shroud of APR+ NPP is different from that of Palo Verde NPP. And the Core Support Barrel(CSB) outer diameter and the flow rate of normal operation of APR+ NPP are larger than those of Palo Verde NPP. Vibration and stress analysis program should be conducted to establish test acceptance criteria. Limited vibration measurement program should be implemented to establish the margin of safety, demonstrate the satisfaction of test acceptance criteria and confirm the similar vibratory response between the APR+ and Palo Verde NPP. Because of the change of normal operation condition, the nominal differences between APR+ and Palo Verde NPP in the structural and hydraulic analysis are studied to determine the measurement locations.

• Elastomers and Composites
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• v.44 no.4
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• pp.366-372
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• 2009

The present study covers the optimal design for a lens module in a mobile phone camera by using the design of experiments (DOE) and finite element (FE) analysis. FE analyses are performed to investigate the effect of design parameters on the amount of torque required to assemble a barrel and a housing part. The DOE approach is then performed to optimize the design parameters in order to maintain an appropriate torque with less variations.

• Development and Reproduction
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• v.15 no.3
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• pp.231-237
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• 2011

The objective of this study was to elucidate the dynamics of microtubules in post-ovulatory aging in vivo and in vitro of mouse oocytes. The fresh ovulated oocytes were obtained from oviducts of superovulated female ICR mice at 16 hours after hCG injection. The post-ovulatory aged oocytes were collected at 24 and 48 hours after hCG injection from in vivo and in vitro, respectively. Immunocytochemistry was performed on ${\beta}$-tubulin and acetylated ${\alpha}$-tubulin. The microtubules were localized in the spindle assembly, which was barrel-shaped or slightly pointed at its poles and located peripherally in the fresh ovulated oocytes. The frequency of misaligned metaphase chromosomes were significantly increased in post-ovulatory aged oocytes after 48 hours of hCG injection. The spindle length and width of post-ovulatory aged oocytes were significantly different from those of fresh ovulated oocytes, respectively. The staining intensity of acetylated ${\alpha}$-tubulin showed stronger in post-ovulatory aged oocytes than that in the fresh ovulated oocytes. In the aged oocytes, the spindles had moved towards the center of the oocytes from their original peripheral position and elongated, compared with the fresh ovulated oocytes. Microtubule organizing centers were formed and observed in the cytoplasm of the aged oocytes. On the contrary, it was not observed in the fresh ovulated oocytes. The alteration of spindle formation and chromosomes alignment substantiates the poor development and the increase of disorders from the post-ovulatory aged oocytes. It might be important to fertilize on time in ovulated oocytes for the developmental competence of embryos with normal karyotypes.