• Proceedings of the KWS Conference
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• 2010.05a
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• pp.74-74
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• 2010

모바일 정보통신기기를 중심으로 전자패키지의 초소형화, 고집적화를 위해 플립칩 공법의 적용이 증가되고 있는 추세이다. 플립칩 패키징 접합소재로는 솔더, ICA(Isotropic Conductive Adhesive), ACA(Anisotropic Conductive Adhesive), NCA(Non Conductive Adhesive) 등과 같은 다양한 접합소재가 사용되고 있다. 최근에는 언더필을 사용하는 플립칩 공법보다 미세피치 대응성을 위해 NCP를 이용한 플립칩 공법에 대한 요구가 증가되고 있는데, NCP의 상용화를 위해서는 공정성과 함께 신뢰성 확보가 필요하다. 본 연구에서는 LDI(LCD drive IC) 모듈을 위한 COF(Chip-on-Film) 플립칩 패키징용 NCP 포뮬레이션을 개발하고 이를 적용한 COF 패키지의 신뢰성을 조사하였다. 테스트베드는 면적 $1.2{\times}0.9mm$, 두께 $470{\mu}m$, 접속피치 $25{\mu}m$의 Au범프가 형성된 플리칩 실리콘다이와 접속패드가 Sn으로 finish된 폴리이미드 재질의 flexible 기판을 사용하였다. NCP는 에폭시 레진과 산무수물계 경화제, 이미다졸계 촉매제를 사용하여 다양하게 포뮬레이션을 하였다. DSC(Differential Scanning Calorimeter), TGA(Thermogravimetric Analysis), DEA(Dielectric Analysis) 등의 열분석장비를 이용하여 NCP의 물성과 경화거동을 확인하였으며, 본딩 후에는 보이드를 평가하고 Peel 강도를 측정하였다. 최적의 공정으로 제작된 COF 패키지에 대한 HTS (High Temperature Stress), TC (Thermal Cycling), PCT (Pressure Cooker Test)등의 신뢰성 시험을 수행한 결과 양산 적용 가능 수준의 신뢰성을 갖는 것을 확인할 수 있었다.

• Proceedings of the KWS Conference
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• 2010.05a
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• pp.78-78
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• 2010

모바일 정보통신기기를 중심으로 패키지의 초소형화, 고집적화를 위해 플립칩 공법의 적용이 증가되고 있고 있으며 접속피치의 미세화에 따라 솔더 및 언더필을 사용하는 C4 공법보다 ACA(Anisotropic Conductive Adhesive), NCA (Non-conductive Adhesive) 등의 접착제를 이용하는 칩본딩 공법에 대한 요구가 증가하고 있다. 특히, NCA 공법의 경우 산업 현장의 대량생산에 대응하기 위해서는 접착제의 속경화 특성이 요구되어 진다. 일반적으로 접착제의 경화거동은 DSC(Differential Scanning Calorimeter)를 사용해 확인하지만, 수초 이내에 경화되는 접착제의 경우는 적용되기 어렵다. 본 연구에서는 이러한 전자패키지용 접착제의 속경화 거동을 효과적으로 평가할 수 있는 방법을 조사 하였다. 실험에서 사용된 접착제는 에폭시계 레진 기반에 이미다졸계 경화제를 사용한 기본적인 포뮬레이션을 사용하였고, 경화시간은 160^{\circ}C에서 1분 이내에 경화되는 특성을 가지고 있다. 경화 거동을 확인하기 위해서 isothermal DSC와 DEA(Dielectric Analysis)의 두가지 방법을 사용해 비교하였다. 두 실험 방법 모두 $160^{\circ}C$를 유지하며 경화 거동을 확인하였고, DoC(Degree of Cure)의 측정오차를 비교 분석하였다. DEA는 이온 모빌리티 변화에 따른 유전손실율을 측정하는 방법으로 80~90% 이후의 경화도는 측정되지 않았지만, 수초 이내에 경화되는 속경화 특성을 평가하기에 적합한 것으로 확인되었다.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.46 no.3
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• pp.36-43
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• 2009

Electrocardiogram (ECG) is a graphical record of the voltages generated during the heart beats, and is very useful in observing the status of the heart of the human or animals. In this paper, an ECG monitoring system is developed for the small animals, such as the rat. This system is very useful in monitoring the side effect of drugs. Since small animals have faster heart rate than the human case, the monitoring system has a faster sampling frequency and processing speed. Furthermore, for a realtime monitoring of the small moving animals, the system is composed of a small wireless ECG module, which is based on the IEEE 802.121.4 wireless physical layer. The developed wireless ECG system can successfully monitor the ECG of small animals, such as the rat.

• Journal of Advanced Marine Engineering and Technology
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• v.41 no.4
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• pp.353-361
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• 2017

As ship-based tourism increases, safe sailing and management are necessary to prevent maritime accidents. Because external rescue support cannot arrive rapidly in the case of ship-related accidents, the initial response is very important for damage minimization. Further, for secondary damage prevention, it is necessary to accurately determine passenger positions. In this paper, considering the characteristics of a ship, the enhanced-Zigbee(e-Zigbee) position determination technology (PDT) is applied, which improved upon the Zigbee PDT by having advantages such as low power consumption and smaller size. According to user needs, a low-cost and high-precision passenger positioning tag and access point(AP) is provided. A ship testbed that yields improved positioning accuracy based on a performance evaluation is constructed.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.36 no.2
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• pp.217-221
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• 2012

As a part of basic research to improve screen quality, which deteriorates when strain occurs within optical sheets in LCD modules for laptop computers, a measurement system is needed to analyze the influence of heat and moisture, which are the main factors causing the strain. It is assumed that the existence of an air gap less of than 0.5 mm inside the LCD module causes humid air from outside to permeate through the module. To investigate this phenomenon, in this study a thin printed circuit board (PCB) of compact sensors that measure temperature and humidity is inserted into LCD modules, and thus, the changes in temperature and humidity can be analyzed in real time. The results can be used as basic data for simulation of the deformation behavior and structural design of LCD modules in the future.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.42 no.4
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• pp.354-359
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• 2009

The productivity of ultra-small rotifer, Synchaeta kitina was investigated at the exchange rate of culture water (10, 20, 30, 40 and 50%) and initial inoculation densities (250, 600 and 900 inds. per mL) in semi-continuous culture. Also, the possibility of mass culture was investigated in a 100 L culture tank. Tetraselmis suecica was used as the feed for S. kitina in all experiments. The production of S. kitina increased with an increase in exchange rate of culture water. The highest production ($82.0{\times}10^5$ inds.) was achieved at 40% exchange rate of culture water. The production of S. kitina increased with an increase of initial inoculation density during the first week and the highest total production ($17.4{\times}10^6$ inds.) was achieved at 900 inds. per mL of initial inoculation density. However, on the second week, all treatments were not significantly different in total production (P>0.05). During the two weeks, total production of S. kitina at 900 inds. per mL of initial inoculation density was higher than at 600 inds. of initial inoculation density, but there was no significant difference (P>0.05). In the 100 L culture tank, density of S. kitina was kept from 516 to 890 inds. per mL and S. kitina was daily harvested $15.5{\times}10^6$ to $26.7{\times}10^6$ during the experimental period. The production cost for 100 million rotifers in semi-continuous culture was 63,656 won. The results from this study indicate that the optimal exchange rate of culture water and initial inoculation density for the semi-continuous culture of ultra-small rotifer, S. kitina are 40% and 600 inds. per mL, respectively.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.300.2-300.2
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• 2014

테라헤르쯔(terahertz : THz)파는 0.1~10 THz 의 범위로 적외선과 방송파 사이에 광대역 주파수 스펙트럼을 차지하고 있으며 직진성, 투과성, 그리고 낮은 에너지(meV)를 가지고 있어 비 파괴적이고 무해한 장점을 지니고 있다. Ti:sapphire laser와 같은 femto-pulse source 등이 많은 발전이 되어 현재 많은 연구와 발전이 이루어지고 있다. femto-pulse source를 이용한 THz 응용에서는 높은 저항, 큰 전자이동도, 그리고 아주 짧은 전하수명의 기판을 요구하는데 저온에서 성장한(low-temperature grown : LT) InGaAs는 격자 내에 Gallium 자리에 Arsenic이 치환 하면서 AsGa antisite가 발생하여 전하수명을 짧아지는 것을 응용하여 가장 많이 이용되고 있다. 본 연구에서는 보다 높은 저항을 얻기 위하여 molecular beam epitaxy를 이용하여 semi-insulating InP:Fe 기판위에 격자 정합된 LT-InGaAs:Be/InAlAs multi quantum well (MQW)를 well과 barrier를 가각 $10{\mu}m$ 씩 100주기 성장을 하였고 Ti와 Au를 각각 30, $200{\mu}m$로 dipole antenna를 제작 하였다. 이 때 Ti:sapphire femto-pulse laser (30 fs/90 MHz)를 excitation source로 사용하였을 때 9000 pA로 LT-InGaAs epilayer (180 pA)보다 50배 이상 큰 전류 신호를 얻을 수 있었다. THz 발생과 검출을 초소형, 초경량, 고효율로 하기 위해서는 fiber-optic를 이용해야 하는데 이때 분산과 산란 손실이 가장 적은 1550 nm 대역에서 많은 연구가 이루어 졌다. 780, 1560 nm의 mode-locking laser (90 fs/100 MHz)를 사용하여 현재 많이 이용되고 있는 Ti:sapphire femto-pulse laser와 비교하여 THz 특성 변화를 확인하는 연구를 진행 하고 있다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2012.10a
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• pp.267-271
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• 2012

In this paper a power management unit for solar energy harvesting is proposed. If solar energy is sufficient, Power Management Unit(PMU) directly supplies load with solar energy. By contrast, if solar energy is insufficient to operate sensor nodes, voltage booster(VB) boosts the solar cell's output voltage, and then PMU supplies load with the harvested energy. The designed circuit had been fabricated using a 018um CMOS process. In the first case, the PMU supplies load with more energy than in the second case. In the second case where a VB is used, the PMU operates to supply load with solar energy even when illumination is low and minimum solar cells with very low output voltage are used.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.8 no.3
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• pp.454-459
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• 2007

In this work, micro-scale, high-performance solenoid-type RF chip inductors utilizing amorphous $Al_2O_3$ core material were investigated. The size of the chip inductors was $0.86{\times}0.46{\times}0.45mm^3$ and copper(Cu) wire with $27{\mu}m$ diameter was used as the coil. High frequency characteristics of the inductance(L), quality factor(Q), impedance(Z), and equivalent circuit parameters of the RE chip inductors were measured and analyzed using an RF impedance/material analyzer(HP4291B with HP16193A test fixture). It was observed that the RF chip inductors with the number of turns of 9 to 12 have the inductance of 21 to 34nH and exhibit the self-resonant frequency(SRF) of 5.7 to 3.7GHz. The SRF of inductors decreases with increasing the inductance and inductors have the quality factor of 38 to 49 in the frequency range of 900MHz to 1,7GHz.

• Journal of Korea Society of Industrial Information Systems
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• v.11 no.5
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• pp.98-104
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• 2006

In this parer, proposed a Miniature inverted F Antenna for Bluetooth applications using folded structure and confirm it through producing and measurement. The proposed antenna as PIFA is optimized the impedance matching and the radiation pattern by positioning of feed line and short line. This antenna is designed with Microwave Studio presented CST and the optimized antenna structure is fabricated. The optimized miniature antenna size is 17.3 * 6 * 0.8 mm, the measured return loss bandwidth is 220MHz at 2.45GHz, the radiation pattern is quasi omni, and the gain is -1 dBi. these results are similar to the simulation data. It is comparatively appropriate for Bluetooth system.