• Proceedings of the Optical Society of Korea Conference
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• 2003.07a
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• pp.208-209
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• 2003

고밀도 광집적회로의 광도파로는 단일모드 광섬유와 굴절률의 차이 및 코어 크기에 의해 모드 부정합 문제가 존재한다. 본 논문은 이러한 모드 부정합 문제를 해결할 수 있는 모드 크기 변환기를 설계 하고 3-D Beam Propagation Method (BPM)을 이용하여 분석하였다. 모드 크기 변환기술에는 마이크로 렌즈, 테이퍼 광섬유, 렌즈화 광섬유가 사용되고 있으나 이는 패키징 가격이 높으며 광섬유와의 정렬 문제가 존재하므로, 집적된 실리콘 기판위에 제작하는 모드 크기 변환기에 대한 연구가 다각도에서 시도되고 있다. (중략)

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.3C
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• pp.297-303
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• 2009

Integral imaging is a well-known 3D image recording and display technique. The huge size of integral imaging data requires a compression scheme to store and transmit 3D scenes. In the conventional compression scheme, the data amount of elemental images depends on the various recording condition such as the positional location of a 3D object, the illumination and specification of the lenslet array even if an identical pickup system is used. In this paper, to reduce the dependence of the image characteristics of elemental images on the pickup conditions, a compression scheme using block division on the elemental image of integral imaging is proposed. The proposed scheme provides an improved compression ratio by considering the local similarity of elemental images picked up from three-dimensional objects according to a positional location. To test the proposed scheme, various elemental images are picked up and a compression process is then carried out u sing a standard MPEG-4. Based on compression ratio results, the proposed compression scheme is improved by approximately 9% compared with the conventional compression method.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.3 no.3
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• pp.149-157
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• 1998

Seasonal changes of topography, sediment grain size and accumulation rate in the Gomso-Bay tidal flat, west coast of Korea, have been studied in order to understand the seasonal accumulation pattern and preservation potential of the tidal-flat sediments. Seasonal levelings across the tidal flat show that the landward movement of both intertidal sand shoals and cheniers accelerates during the winter and typhoon periods, but it almost stops in summer when mud deposition is instead predominant at the middle and upper tidal flats. Seasonal variations of mean grain size were largest on the upper part of middle tidal flat where summer mud layers were eroded during the winter and typhoon periods. Measurements of accumulation depths from sea floor to basal plate reveal that accumulation rates were seasonally controlled according to the elevation of tidal-flat surface. The upper tidal flat where the accumulation rate of summer was generally higher than that of winter was characterized by a continuous deposition throughout the entire year, whereas in the middle tidal flat, sediment accumulations were concentrated in winter relative to summer and were intermittently eroded by typhoons. The lower tidal flat were deposited mostly in winter and eroded during summer typhoons. Can cores taken across the tidal flat reveal that sand-mud interlayers resulting from such seasonal changes of energy regime are preserved only in the upper part of the deposits and generally replaced by storm layers downcore. Based on above results, it is suggested that the storm deposits by winter storms and typhoons would consist of the major part of the Gomso-Bay sediments.

• Korean Journal of Optics and Photonics
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• v.15 no.2
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• pp.171-176
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• 2004

A light deflector integrated laser diode(LD) was fabricated and the characteristics of LD and ourput beam deflection as a function of deflector injection current were measured. To integrate the deflector with LD, a passive waveguide was integrated with the LD and a triangular-type light deflector was fabricated on the upper clad of the passive waveguide section. Light deflection from the fabricated light deflector is controlled by the effective refractive index variation induced by carrier injection. To characterize the effect of the deflector injection current, threshold current, slope efficiency, and output beam spectrum were measured as a function of deflector injection current. From these measured data, the increment in the threshold current and the decrement of the slope efficiency were observed. However, the output beam spectrum was not affected by the deflector. The Beam Propagation Method(BPM) was used to simulate the proposed device and the light deflection was measured by the far-field pattern of the output beam as a function of the deflector injection current. In the fabricated deflector integrated LD, the deflection angle of 1.9$^{\circ}$ at the injection current of 15 ㎃ was obtained.

• Korean Journal of Optics and Photonics
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• v.6 no.3
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• pp.233-238
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• 1995

'#65279;We made $P_2O_5-SiO_2$ films on silicon for integrated optics application by low pressure chemical vapor deposition using TEOS(tetraethylorthosilicate), TMPite(trimethylphosphite) and phosphine($PH_3$). And We studied and compared between TMPite and PH, as a dopant of P in PSG films in the aspect of the de,position characteristics. Deposition rate of TMPate-PSG films was $55 \AA/min$ which was smaller than 90 A/min , that of $PH_3-PSG$ films. Thickness deviation of TMPate-PSG films was 2% and that of PH3-PSG was 4.5%. So TMPate-PSG films had a good quality in thickness uniformity. The range of refractive index was controlled from 1.445 to 1.468 at 633 nm in TMPate-PSG films and it was controlled from 1.456 to 1.476 in $PH_3-PSG$ films.

• Parasites, Hosts and Diseases
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• v.21 no.2
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• pp.142-149
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• 1983

Epidemiological studies on the reinfetion pattern of Ascaris lumbricoides were undertaken by means of blanket mass chemotherapy and worm collection in a rural village in Korea, during 1977~1980. The study objectives were to determine the age (sex)-specific reinfection rate during 2, 4, 6 and 12 months through repeated mass chemotherapy with pyrantel pamoate, and to observe the familial aggregation tendency of the reinfected cases. The results obtained are as follows: 1. The age (sex)-reinfection curve revealed that the reinfection rate is much higher in younger individuals than in olders in all of 4 kinds of interval chemotherapy groups. The highest reinfection rate and the highest burden of reinfected worms were observed in preschool children, followed by primary school students. Such fluctuation in the age-specific reinfection rates was more pronounced in males than in females. 2. There was noted a significant tendency of familial aggregation among the reinfected cases. It is suggested that reinfection occurs never randomly but preferably to the members of certain household families. From these reinfection analyses, it is inferred that the principal mode of A. lumbricoides transmiSSIOn in the surveyed rural area is likely to be of 'dooryard type', in which case children and certain family members are more preferably reinfected. It is also suggested that the preschool children should be included in the primary targets of mass control programme.

• Korean Journal of Optics and Photonics
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• v.9 no.3
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• pp.156-161
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• 1998

We developed aerosol flame deposition method and made stress-free Pyrex-based optical waveguide on silicon substrate using this method. Zr is doped to control the refractive index of Pyrex waveguide layers. The refractive index of the film changes from 1.460 to 1.475 as the content of Zr changes from 0 to 3 wt%. Er is doped to see the possibility of applying this Pyrex waveguide as PLC-type (Planar Lightwave Circuit) optical amplifier. The refractive index of the film changes from 1.460 to 1.465 as the content of Zr changes from 0 to 1 wt%. Light launching using a prism coupler to the fabricated waveguide showed good quality for application to PLC. The polarization dependence of refractive-index of the Pyrex film is measured to be less than $2{\times}10^{-4}$.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.11a
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• pp.224-224
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• 2008

고주파용 집적회로 기판소재로의 응용을 위해 세라믹 특유의 취성을 개선한 $Al_2O_3$-polyimide 복합체 후막을 에어로졸데포지션법을 이용해 제조하고 그 특성을 평가하였다. 그 결과 기공이 거의 없이 치밀한 구조를 갖는 $Al_2O_3$-polyimide 복합체 후막이 구리 및 유리 기판 상에 성막 되었음이 SEM 및 EDS을 통해 확인되었다. 상용 $Al_2O_3$ 출발 파우더를 사용한 복합체 제조시 1 MHz에서 유전율은 6.7, 유전 손실률은 0.026 이었다. 유전특성의 향상을 위하여 에어로졸데포지션법으로 성막된 $Al_2O_3$-polyimide 복합체 후막의 후속 열처리 결과 유전손실율이 0.026에서 0.007로 감소하였다. 또한 집적회로 기판소재로의 응용을 위한 저온화 제조공정 확립을 위하여 $Al_2O_3$ 출발 파우더의 공정 전 열처리 후 상온에서 성막한 경우에도 어떠한 후속 열처리 없이 유전손실률이 0.007로 감소하였다.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2018.06a
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• pp.80-80
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• 2018

실리콘 관통전극 (Through Silicon Via, TSV)는 메모리 칩을 적층하여 고밀도의 집적회로를 구현하는 기술로, 기존의 와이어 본딩 (Wire bonding) 기술보다 낮은 소비전력과 빠른 속도가 특징인 3차원 집적기술 중 하나이다. TSV는 일반적으로 도금 공정을 통하여 충전되는데, 고종횡비의 TSV에 결함 없이 구리를 충전하기 위해서 3종의 유기첨가제(억제제, 가속제, 평탄제)가 도금액에 첨가되어야 한다. 이러한 첨가제 중 결함 발생유무에 가장 큰 영향을 주는 첨가제는 평탄제이기 때문에, 본 연구에서는 이미다졸(imidazole) 계열, 이민(imine) 계열, 디아조늄(diazonium) 계열 및 피롤리돈(pyrrolidone) 계열과 같은 평탄제(leveler)의 작용기에 따라 TSV 충전 성능을 조사하였다. TSV 충전 시 관능기의 거동을 규명하기 위해 QCM (quartz crystal microbalance) 및 EQCM (electrochemical QCM)을 사용하여 흡착 정도를 측정하였다. 실험 결과, 디아조늄 계열의 평탄제는 TSV를 결함 없이 충전하였지만 다른 작용기를 갖는 평탄제는 TSV 내 결함이 발생하였다. QCM 분석에서 디아조늄 계열의 평탄제는 낮은 흡착률을 보이지만 EQCM 분석에서는 높은 흡착률을 나타내었다. 즉, 디아조늄 계열의 평탄제는 전기 도금 동안 전류밀도가 집중되는 TSV의 상부 모서리에서 국부적인 흡착을 선호하며 이로 인하여 무결함 충전이 달성된다고 추론할 수 있다.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.45 no.12
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• pp.66-73
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• 2008

At MANET, Broadcasting message transmission makes throughput decrease because all of MANET nodes are participated at retransmitting broadcasting messages. Especially, burst RREQ transmission causes broadcasting message congestion and inter-RREQ transmission delay. In this paper, we propose a RREQ aggregation method applied to the sender node and intermediate node for solving the problem caused by burst RREQ generation. And we analysis performance of the proposed method by examining at the real testbed.