• Journal of the Institute of Electronics Engineers of Korea SD
• /
• v.46 no.4
• /
• pp.15-20
• /
• 2009

In a detection system based on laser light scattering, focusing an excitation laser beam into a focal point of a channel in a microfluidic chip is important for obtaining the highest excitation intensity, and consequently for obtaining a laser light scattering signal using a photodetector with a high efficiency. In this paper, we present a polydimethylsiloxane (PDMS) microfluidic chip consisting of an integrated PDMS microlens for cell detection based on laser light scattering. We fabricated PDMS microlens for optical detection system by simply putting down on PDMS chips. The PDMS microlens was fabricated by photoresist reflow and replica molding. This fabrication technique is simple and has an excellent property in terms of the microlens and a high-dimensional accuracy. The PDMS microlens integrated on the PDMS microfluidic chip has been verified to improve the laser intensity, and accordingly, the signal-to-noise ratio and sensitivity of laser light scattering detection for red blood cells(RBCs)

• Journal of the Institute of Electronics Engineers of Korea SC
• /
• v.48 no.6
• /
• pp.82-90
• /
• 2011

This paper proposes an advanced outdoor localization algorithm of a GPS(global positioning system)-INS(inertial navigation system) integration system. In order to reduce noise from the internal INS sensors, discrete wavelet transform and variable threshold method are utilized. The UPF (unscented particle filter) combines GPS information and INS signals to implement precise outdoor localization algorithm and to reduce noise caused by the acceleration, deceleration, and unexpected slips. The conventional de-noising method is mainly carried out using a low pass filter and a high pass filter which essentially result in signal distortions. This newly proposed system utilizes the vibration information of actuator according to fluctuations of the velocity to minimize signal distortions. The UPF also resolves non-linearities of the actuator and non-normal distributions of noises. Effectiveness of the proposed algorithm has been verified through the real experiments and the results are demonstrated.

• Journal of the Microelectronics and Packaging Society
• /
• v.21 no.1
• /
• pp.25-29
• /
• 2014

In this study, an optical PCB was proposed which can overcome the limitations of the conventional PCB, and a new structure with pluggable lens was considered for a high-efficient passive alignment. The structure was a lens-added optical waveguide for the improvement of misalignment between the lens and the waveguide in the alignment. Also, as it had a barrier-type structure to prevent the surface damage of the lens by desorption, the high-efficient passive alignment can be realized. The structure was designed by optimizing the simulation and the fabrication process of the pluggable lens structure was conducted using the repetitive photolithography and the thermal reflow. The optical waveguide with the lens-integrated pluggable interconnection was fabricated by the imprint process using the polydimethylsiloxane(PDMS) replica mold. Therefore, we confirmed the possibility of pluggable lens-added optical waveguide structure fabrication for high-efficient passive alignment.

• Journal of the Microelectronics and Packaging Society
• /
• v.15 no.2
• /
• pp.47-54
• /
• 2008

In this paper, we studied how and why did abnormal IMC growth at component affect on board level mechanical reliability. First, interfacial reactions between Sn2.5Ag0.5Cu solder and electrolytic Ni/Au UBM of component side were investigated with reflow times and thermal aging time. Also, to compare mechanical reliability of component level, shear energy was evaluated using the ball shear test conducted with variation of shear tip speed. Finally, to evaluate mechanical reliability of board level, we surface-mounted component fabricated with each condition on PCB side. After conducting of 3 point bending test and impact test, we confirmed solder joint crack mode using cross-sectioning and dye & pry penetration method.

• Journal of Broadcast Engineering
• /
• v.17 no.6
• /
• pp.990-1003
• /
• 2012

In this paper, the possibility and necessity of the digital broadcasting propulsion in AM and FM is presented based on DRM and DRM+ transmission modes, They are the members of series technological family in digital radio development. As the frequency utilization, the application of DRM+ is flexible in any mode such as IN-BAND or OUT-OF-BAND. When the digital audio broadcasting is planned at LOW-VHF bandwidth such as TV channel No.5 and NO.6 being adjacent to FM band and OUT-Of-BAND DRM+ technology is applied, there is no collision and jamming. Particularly, in the IN-BAND Hybrid mode, it is mentioned that there was the difficulty problem for multiple SFN transmitters uses. Not like the IN-BAND mode the OUT-OF-BAND mode lets multiple transmitters, because neighbor transmitters do not interfere each other. Digital transmitter can be combined with the existing FM transmitter. The intensity of power and size of area can be easily determined according to local broadcasters' condition. And the OUT-OF-BAND mode is advantageous for AM/FM integration in digital radio receiver manufacturing, which makes the conversion schedule much shorter.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.34 no.2
• /
• pp.237-243
• /
• 2010

This paper presents a study on the helical gear inspection system for application to vehicle transmission gear manufacturing lines. The special gear profile inspection system is not suitable for manufacturing lines due to the measuring time. The master gear method, which was used in this study and compared with the machined gear in the line, is more efficient and economical. In this paper, three helical gear inspection parameters were of concern: nick, run-out, and PCD (pitch circle diameter) error. To evaluate its influence on the accuracy, the gear measuring system was also studied. This system can be useful in practical vehicle transmission gear manufacturing lines, where imported equipment is currently being used.

• Journal of architectural history
• /
• v.20 no.3
• /
• pp.39-57
• /
• 2011

The goal of this paper is to analyze the relationship between pedagogy and the emergence of contemporary Korean architecture after the 1990s. For this purpose, the paper deals with the education and work of two important contemporary Korean architects, Kim Seung Hoy and Choi Wook. Kim and Choi were part of a group of young architects that went abroad in the 1980s to study at the centers of architectural education in Europe and the United States. Through their education and work, the paper discusses the relationship among education, history, and design practice in architecture. During their studies at Michigan University and IUAV in Venice, they were commonly influenced by Colin Rowe through their studios. In the case of Kim Seung Hoy, he was introduced to the Beaux Arts logic of the analytique and esquisse through the teaching of Steven Hurrt, a disciple of Colin Rowe. Choi Wook took studios that involved formal analysis and comparison of Palladio and Le Corbusier. The paper further analyzes their works in Korea by employing the concepts of fragments and systems, ignorance and knowledge. The paper concludes that, in Korean contemporary architecture, fragments and systems, ignorance and knowledge, lie in the middle of ongoing creative process that must distinguished from the West, where architectural history provides an established tradition of systematic knowledge.

• Proceedings of the KWS Conference
• /
• 2010.05a
• /
• pp.76-76
• /
• 2010

무연솔더 재료를 자동차 전장품에 적용하기 위해서는 고온환경에 대한 내구성 및 진동 인자에 대한 영향을 고려해야한다. 특히, ELV(End of Life Vehicles) 지침이 개정됨에 따라 고온용 무연솔더 재료에 대한 재평가가 반드시 필요한 시점이다. 이에 대해 본연구에서는 현재 상용화 된 Pb-free솔더의 재료들 중 총 4종의 Solder을 선정하여 자동차 환경에 부합하는 진동조건하에서 시험해보았다. 그리고 미세조직의 특성, 접합부 형성시의 기계적 강도 및 접합부의 신뢰성을 평가하여 보았다. 각각의 조성에 대한 CHIP type과 QFP type의 실장부품을 준비하였으며, 각각의 조성별로 솔더 페이스트로 Daisy Chain PCB에 접합하여 조성에 따른 비교 데이터를 구축할 수 있었다. 리플로우 공정후 초기의 미세조직 및 전당강도, 저항값을 측정하여 진동시험에 따른 데이터와 비교하였다. 주파수는 10Hz~1,000Hz였으며, 진동가속도는 $29.4m/s^2$, 20시간의 랜덤진동이 적용되는 동안 챔버내의 온도는 상온으로 유지되었다. 진동시험과 이에 따른 저항측정을 통하여 진동 주파수와 시간에 따른 실장 부품이 받는 진동 영향과 실시간 저항값을 측정하였으며, 이때의 미세조직 비교를 통해 진동특성을 평가하였다. 진동 주파수에 따른 저항값의 변화가 있었으며, 진동전후 전단강도에도 영향을 주었다. QFP type에서는 SAC105가 진동에 가장 취약하였으며, CHIP type에서는 SACX0307이 진동에 가장 취약하였다.

• Journal of the Microelectronics and Packaging Society
• /
• v.15 no.4
• /
• pp.9-15
• /
• 2008

Microstructure and contact resistance of the Au-Sn solder joints were characterized after flip-chip bonding of the Au/Sn bumps processed by successive electrodeposition of Au and Sn. Microstructure of the Au-Sn solder joints, formed by flip-chip bonding at $285^{\circ}C$ for 30 sec, was composed of the $Au_5Sn$+AuSn lamellar structure. The interlamellar spacing of the $Au_5Sn$+AuSn structure increased by reflowing at $310^{\circ}C$ for 3 min after flip-chip bonding. While the Au-Sn solder joints formed by flip-chip bonding at $285^{\circ}C$ for 30 sec exhibited an average contact resistance of 15.6 $m{\Omega}$/bump, the Au-Sn solder joints reflowed at $310^{\circ}C$ for 3 min after flip-chip bonding possessed an average contact resistance of 15.0 $m{\Omega}$/bump.

• The Journal of the Korea Contents Association
• /
• v.10 no.3
• /
• pp.141-148
• /
• 2010

The aim of this paper is to propose a communication middleware which makes it possible to easily and efficiently develop the networking support for multi-user applications. Even though existing middleware and development tools provides lots of functionalities to realize distributed applications, they are purely low-level services passing the most development efforts to developers, or too specialized for a specific application. It brings a challenging issue of how the middleware supports general and efficient high-level mechanisms. To meet different networking and interaction requirements of multi-user applications, we propose various schemes to provide the communication architecture, the user membership management, the content transmission mechanism and the event management. Our middleware provides developers with application-level APIs and configuration files so that the different interaction requirements of a multi-user application can be easily handled in the developers' point of view.