• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.1
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• pp.170-178
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• 2019

Recently, as the interest in energy savings has increased, there has been increasing use of LED lighting, which is an eco-friendly device that replaces high energy consuming fluorescent lamps and incandescent lamps. In the case of a high output LED, however, the life time is shortened due to deterioration caused by heat generation. As a solution to this problem, this paper evaluated the LED life extension effect by increasing the convective heat transfer coefficient of the heat sink surface for LED packaging. A roughing process was carried out using sandpaper and sand blasting. The changes in surface roughness and surface area after each surface treatment process were evaluated quantitatively and the convective heat transfer coefficient was measured. When sandblasting and sandpaper were used to roughen the aluminum surface, a higher convection heat transfer coefficient was obtained compared to the untreated case, and a high heat dissipation efficiency of 82.76% was obtained in the sandblast treatment. Therefore, it is expected that the application of heat dissipation to the heat sink will extend the lifetime of the LED significantly and economically by increasing the heat efficiency.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.8 no.2
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• pp.39-43
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• 2002

Increasing use of plastics in food packaging materials has led to the issue of food-plastic packaging materials's mutual interactions. Although the plastic packaging materials are generally considered as inert, migration and sorption of fatty materials are some of the problems associated with their use. So, this work investigated the compatibility of three structurally different polymers, polypropylene (PP), polyethyleneterephthalate (PET) and ethylene vinyl alcohol copolymer (EVOH) with some structurally different food fats. The main goal was to study the sorption of food fats by the plastic films and to see what extent mechanical properties of the plastic films was affected by plasticization effect due to sorption of fatty materials. PP, PET, and EVOH films was immersed in pure triglycerides, and then extracted with hexane and analyzed for the amounts of fat migrated. The sorbed films were also investigated for change in mechanical properties. Result showed that structural factor of the films and fatty materials plays important role in th migration process. The fat with the simplest structure are migrated more easily that the fat with more complex structure. However, structural effect of migration was varied according to degree of crystallinity and density of plastic films. In addition to that, polarity of plastic film was affected migration of fatty materials significantly. Additional research is needed to justify the reason why migration of fatty materials into the films was affected by polarity and structural integrity.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.5
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• pp.2113-2120
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• 2013

In this study, an efficient machine vision based inspection system is developed for the in-line measurement of phosphor resin dispensing shapes on LED chip package. Since the phosphor resin (target material) has semitransparent characteristics, illuminated light beam is reflected from the bottom of the chip as well as from the surface. Since such phenomenon can deteriorate inspection reliability, a white LED and a 635nm laser slit beams are experimentally tested to decide suitable illumination optics. Also, specular and diffuse reflection methods are tested to decide suitable optical triangulation. As a result, it can be known that the combination of a white slit beam source and specular reflection method show the best inspection results. The Catmull-Rom spline interpolation is applied to the obtained data to form smoother surface. From the results, it can be conclude that the developed system can be sucessfully applied to the in-line inspection of LED chip packaging process.

• Journal of Welding and Joining
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• v.31 no.3
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• pp.11-16
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• 2013

Through-silicon-via (TSV) is a major technology in microelectronics for three dimensional high density packaging. The 3-dimensional TSV technology is applied to CMOS sensors, MEMS, HB-LED modules, stacked memories, power and analog, SIP and so on which can be employed to car electronics. The copper electroplating is widely used in the TSV filling process. In this paper, the various Cu filling methods using the control of the plating process were described in detail including recent studies. Via filling behavior by each method was also introduced.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2009.10a
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• pp.631-636
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• 2009

This paper presents design and analysis of ultrasonic vibrator featuring the piezoelectric actuator. After describing a geometric configuration of the proposed vibrator, an analytical model of the ultrasonic vibrator is formulated by adopting liquid film pattern theory and wave theory. The dynamic analysis and geometric optimization are then undertaken using a software ANSYS. The optimization is performed by taking the amplitude of the tip displacement as an objective function. The fluid flow characteristics of the proposed vibrator are analyzed by taking three different fluids: water, silicon oil and ethylene-glycol. This is achieved using a software FLUENT.

• International Journal of Internet, Broadcasting and Communication
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• v.7 no.2
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• pp.161-167
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• 2015

The performance of high power LEDs highly depends on the junction temperature. Operating at high junction temperature causes elevation of the overall thermal resistance which causes degradation of light intensity and lifetime. Thus, appropriate thermal management is critical for LED packaging. The main goal of this research is to improve thermal resistance by optimizing and comparing nano-pore silicon-based thermal substrate to insulated metal substrate and direct bonded copper thermal substrate. The thermal resistance of the packages are evaluated using computation fluid dynamic approach for 1 W single chip LED module.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.19 no.12
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• pp.1289-1295
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• 2009

This paper presents design and analysis of ultrasonic vibrator featuring the piezoelectric actuator. After describing a geometric configuration of the proposed vibrator, an analytical model of the ultrasonic vibrator is formulated by adopting liquid film pattern theory and wave theory. The dynamic analysis and geometric optimization are then undertaken using a software ANSYS. The optimization is performed by taking the amplitude of the tip displacement as an objective function. The fluid flow characteristics of the proposed vibrator are analyzed by taking three different fluids: water, silicon oil and ethylene-glycol. This is achieved using a software FLUENT.

• The Optical Journal
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• s.139
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• pp.56-57
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• 2012

인쇄회로기판과 표면실장기술, LED, 인쇄전자, 기능성 필름, 광학 및 레이저기기 등 전자 제조산업 전반에 걸친 기술들을 총집결한 국내 최대 산업전문전시회인 'Electronics Manufacturing Korea 2012(이하 EMK2012)'가 지난 4월 11일부터 13일까지 코엑스 Hall C, D에서 펼쳐졌다. EMK2012는 SMT/PCB & NEPCON KOREA, LED Packaging EXPO, Film Technology Show와 함께 올해부터 Printed Electronics & Electronic Materials Show과 Photonics Seoul(포토닉스 서울)이 추가돼 총 5개의 전시회가 동시에 열렸다. 약 25개국 300업체가 1000부스 규모로 참가한 이번 전시회는 기존의 SMT, PCB, 전자부품, FPD 생산기자재와 더불어 LED 생산기자재, 광학기기, 레이저 산업 등 전자산업 관련 각종 생산기자재와 제품 등을 선보이며 최신 기술을 교류하는 기회였다.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.2
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• pp.401-407
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• 2014

There are increasing interests in COB (Chip On Board) that densely arranged many LED chips on one board in order to solve the heat issue. There are many problems being on the rise: the lifespan decreases as the temperature of LED devices increases; Red Shift phenomenon, in which wave length of spectral line moves from original wave length to long wave length, occurs; and optical power decreases as $T_j$ increases. In order to resolve such problems, this study selected the optimum thickness and length of Fin, planned the second Heat sink that is optimum for COB LED with 15W, and analyzed thermal mode by Solid Works Flow Simulation through 15W COB packaging with the planned Heat sink. 15W COB down-light Heat sink that is produced based on this analysis was utilized to analyze thermal mode through contact thermometer and electrical properties through Kelthley 2430.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.6
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• pp.2624-2630
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• 2013

In LED chip packaging, die bonding is a very important process which fixes the LED chip on the lead flame to provide enough strength for the next process. During the process, inspection processes are very important to detect exact locations of dispensed epoxy dots and to determine bonding status of dies whether they are lies at exact positions with sufficient bonding strength. In this study, a useful machine vision based inspection system is proposed for the LED die bonder. In the proposed system, 2 cameras are used for epoxy dot position detection and 2 cameras are sued for die attaching status determination. New vision processing algorithm is proposed, and its efficiency is verified through required field experiments. Measured position error is less than $X:-29{\mu}m$, $Y:-32{\mu}m$ and rotation error:$3^{\circ}$ using proposed vision algorithm. It is concluded that the proposed machine vision based inspection system can be successfully implemented on the developed die bonding system.