• Proceedings of the KIEE Conference
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• 2015.07a
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• pp.1285-1285
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• 2015

현재 전력난에 의해 에너지 절감이라는 말은 가정 및 산업 현장 곳곳에서 들을 수 있다. 에너지 절감 대책 중 하나가 몇 년전 정부에서 발표한 백열등 수입 및 유통금지가 있다. 그 효과로 LED 산업이 각광 받게 되었다. 다양한 LED 산업 및 기술에서도 신뢰성 및 성능 분야는 항상 진화하고 많은 기업들이 집중하고 있다. LED에서 중요한 요소인 방열성능을 개선시키기 위해 많은 연구를 행하고 있다. 그리고 광원 개발분야에서도, 반도체 광원의 LED PKG의 다량 실장으로 고출력을 행하는 것 보다는 기판위에 Blue Chip을 실장하여 제작하는 고출력 광원의 기술로 집중되고 있다. 이 논문에서는 고출력 광원인 COB(Chip On Board) LED의 방열성능 개선을 다루었다. 기판의 구조 변형으로 방열특성 개선 대안을 제시하였다. Via hole과 Cavity를 이용한 구조를 제안하였다. 그에 대한 해석 방법으로는, 구조적인 해석과 수치적인 해석을 활용하였다. 그 결과로는 약 13~40%의 방열성능 개선을 나타내었다.

• Journal of Surface Science and Engineering
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• v.46 no.4
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• pp.153-157
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• 2013

The defect like the void or seam is frequently generated in the PCB (Printed Circuit Board) Via-Filling plating inside via hole. The organic additives including the accelerating agent, inhibitor, leveler, and etc. are needed for the copper Via-Filling plating without this defect for the plating bath. However, the decomposition of the organic additive reduces the lifetime of the plating bath during the plating process, or it becomes the factor reducing the reliability of the Via-Filling. In this paper, the interaction of each organic additives and the decomposition of additive were discussed. As to the accelerating agent, the bis (3-sulfopropyl) disulfide (SPS) and leveler the Janus Green B (JGB) and inhibitor used the polyethlylene glycol 8000 (PEG). The research on the interaction of the organic additives and decomposition implemented in the galvanostat method. The additive decomposition time was confirmed in the plating process from 0 Ah/l (AmpereHour/ liter) to 100 Ah/l with the potential change.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.19 no.9
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• pp.825-831
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• 2006

As an increase of chip complexity and level of chip integration, chip input/output (I/O) pad pitches are also drastically reduced. With arrival of high complexity SoC (System on Chip) and SiP (System in Package) products, conventional horizontal type probe card showed its limitation on probing density for wafer level test. To enhance probing density, we proposed new vertical type probe card that has the $70{\mu}m$ probe needle with tungsten wire in $80{\mu}m$ micro-drilled hole in ceramic board. To minimize alignment error, micro-drilling conditions are optimized and epoxy-hardening conditions are also optimized to minimize planarity changes. To apply wafer level test for target devices (T5365 256M SDRAM), designed probe card was characterized by probe needle tension for test, contact resistance measurement, leakage current measurement and the planarity test. Compare to conventional probe card with minimum pitch of $50{\sim}125{\mu}m\;and\;2\;{\Omega}$ of average contact resistance, designed probe card showed only $22{\mu}$ of minimum pitch and $1.5{\Omega}$ of average contact resistance. And also, with the nature of vertical probing style, it showed comparably small contact scratch and it can be applied to bumping type chip test.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.16 no.4 s.95
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• pp.402-409
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• 2005

In analog and digital electronic systems, crosstalk between transmission lines on the printed circuit board can degrade the performance of equipment operations. This paper presents a technique to analyze the effects of via fence, which is based on additional transmission lines grounded by vias. The technique is composed of a circuit concept approach for transmission line sections md an impedance modeling of via hole sections. All sections are represented by ABCD parameters and they are cascaded. Finally, this technique was verified by comparing the measurement results with the simulation ones.

• Journal of the Korea Furniture Society
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• v.28 no.2
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• pp.126-134
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• 2017

This study explores PyeongSang, a piece of traditional Korean furniture, in order to make people know the details about what the piece is in the first paper. And based on the paper, PyeongSang will be developed as moulded multi-useful beds and sofas adapting the joint and ornament from the structure and pattern of the piece in the next paper. As the result, it appeared as two styles such as bed types mentioned as SalPyeongSang and ttulmaru in Korean. The pieces have been used from the three Kingdoms period in Korean history. The styles appeared as the structure of four parts with the lower fences called as nangan, the seats jointed by thin wood pieces, the wind hole, and the legs of foot types. The parts were beautifully carved with the ornament such as lattice patterns like geokjamun and manjamun, flower patterns like dangchomun, elephant eyes patterns like ansangmun from the Korean tradition. And the legs showed various shapes such as supports transformed from horse foots, tiger legs and bamboo, and board types carved with elephant eyes and geometric patterns. Hence, in the next paper based on this paper, PyeongSang will be developed as moulded multi-useful beds and sofas adapting the joints and ornaments from the structure and patterns of the piece.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.26 no.10
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• pp.1997-2007
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• 2002

Composite air spindles are appropriate for the high-speed and the high-precision machining as small hole drilling of printed circuit board (PCB) or wafer cutting for manufacturing semiconductors because of the low rotational inertia, the high damping ratio and the high fundamental natural frequency of composite shaft. The axial load and stiffness of composite air spindles fur drilling operation are determined by the thrust ben ring composed of the air supply part mounted on the housing and the rotating part mounted on the rotating shaft. At high-speed rotation, the rotating part of the thrust bearing should be designed considering the stresses induced by centrifugal force as well as the axial stiffness and the natural frequency of the rotating shaft to void the shaft from failure due to the centrifugal force and resonant vibration. In this work, the air supply part of the thrust bearing was designed considering the bending stiffness of the bearing and the applied load. The rotating part of the thrust bearing was designed through finite element analysis considering the cutting forces during manufacturing as well as the static and dynamic characteristics under both the axial and con trifugal forces during high-speed rotation.

• Current Optics and Photonics
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• v.3 no.1
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• pp.16-21
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• 2019

We present a broad-bandwidth comb-spacing-swept source (CSWS) based on a differential polarization delay line (DPDL) for interferometric three-dimensional (3D) imaging. The comb spacing of the CSWS is repeatedly swept by the tunable DPDL in the multiwavelength source to provide depth-scanning optical coherence tomography (OCT). As the polarization differential delay of the DPDL is tuned from 5 to 15 ps, the comb spacing along the wavelength continuously varies from 1.6 to 0.53 nm, respectively. The wavelength range of various semiconductor optical amplifiers and the cavity feedback ratio of the tunable fiber coupler are experimentally selected to obtain optimal conditions for a broader 3-dB bandwidth of the multiwavelength spectrum and thus provide a higher axial resolution of $35{\mu}m$ in interferometric OCT imaging. The proposed CSWS-OCT has a simple imaging interferometer configuration without reference-path scanning and a simple imaging process without the complex Fourier transform. 3D surface images of a via-hole structure on a printed circuit board and the top surface of a coin were acquired.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.4 no.4
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• pp.390-399
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• 1999

Siliceous and calcareous deep-sea core sediments were collected by a multiple corer from the KODOS (Korea Deep Ocean Study) area, northeast equatorial Pacific, to compare vane shear strengths measured by two different apparatuses and in different places of on-board and on-land laboratories. The apparatuses were 1) a hand-held vane with four blades of $2.0{\times}2.0$ cm, and 2) a motorized shear vane system with four blades of $1.0{\times}0.88$ attached on a rotational viscometer. Depth profiles of shear strengths of core samples determined by the apparatuses do not show any consistent difference. Also, there is no consistent difference between shear strength values measured on-board and on-land laboratories after storing the core samples for three months in a cold room by a motorized shear vane system. However, there are considerable differences between depth profiles of shear strengths measured at four different points (holes) of a core sample. Moreover, significant differences among the profiles of different tube samples from a multiple corer within a sampling station were observed. Heterogeneity in physical properties of each depth and sediment column, possibly due to bioturbation and bottom current flows, is likely responsible for the differences in the geotechnical properties.

• The Korean Journal of Physiology and Pharmacology
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• v.18 no.3
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• pp.191-200
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• 2014

We investigated the anxiolytic-like activity of ${\alpha}$-asarone (AAS) from Acorus gramineus in an experimental rat model of anxiety induced by repeated administration of the exogenous stress hormone corticosterone (CORT). The putative anxiolytic effect of AAS was studied in behavioral tests of anxiety, such as the elevated plus maze (EPM) test and the hole-board test (HBT) in rats. For 21 consecutive days, male rats received 50, 100, or 200 mg/kg AAS (i.p.) 30 min prior to a daily injection of CORT. Dysregulation of the HPA axis in response to the repeated CORT injections was confirmed by measuring serum levels of CORT and the expression of corticotrophin-releasing factor (CRF) in the hypothalamus. Daily AAS (200 mg/kg) administration increased open-arm exploration significantly in the EPM test, and it increased the duration of head dipping activity in the HBT. It also blocked the increase in tyrosine hydroxylase (TH) expression in the locus coeruleus (LC) and decreased mRNA expression of brain-derived neurotrophic factor (BDNF) and its receptor, TrkB, in the hippocampus. These results indicated that the administration of AAS prior to high-dose exogenous CORT significantly improved anxiety-like behaviors, which are associated with modification of the central noradrenergic system and with BDNF function in rats. The current finding may improve understanding of the neurobiological mechanisms responsible for changes in emotions induced by repeated administration of high doses of CORT or by elevated levels of hormones associated with chronic stress. Thus, AAS did exhibit an anxiolytic-like effects in animal models of anxiety.

• Journal of the Korean Professional Engineers Association
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• v.17 no.3
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• pp.6-21
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• 1984

A rock slide in amount of 100 tons in weight happened at 7: 10 a.m., 4th October 1982, on the southwestern ridge of Mt. Seunghag, Busan City. The original rock mass of the rock slide is located 850m west from the Dangri Crushed Stone Quarry. The geology of the area consists of agglomerate, andesite, andesitic tuff, and shale hornfels of the Cretaceous Yucheon Group. The rock blocks were first shifted along the steep joint plane on an andesite outcrop at the site and then to the eastern foot of the mountain slope where some private houses are placed. The mountain slope is covered with thick superficial soil. A slided monolithic-block with 83 tons in weight from the rock slide met with an accident of striking against a house with a tremendous force, to which much damage was done as much as its half was destroyed. The rock-slided block pierced the board-floored room only posited at the center and by the bedroom of the house making a pass like a bullet hole, and hence cut a big pine tree with 24 centimeters in diameter at a distance of 26 meters down the house. However nobody was killed or injured in the stricken house, though seven family members were stayed therein at the very time of accident. They really met a rare opportunity in an unhappy disaster. Measurements of the rock slide were made in the course of the field survey. The monolithic mass was transported by way of saltation, rolling, and sliding to a distance of 300 meters down along the slope dipping 30$^{\circ}$ east. It took about 16 seconds front tile outcrop to the terminal. The acceleration value of the monolithic rock slide is 2.35m/sec$^2$.