• Proceedings of the Acoustical Society of Korea Conference
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• autumn
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• pp.53-56
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• 1999

ITU-T 국제 표준화 기구에서 인터넷 폰과 화상회의를 목적으로 개발된 G.723.1 음성 부호화기는 잡음 구간에서의 전송률을 낮추기 위한 방법으로 VAD(Voice Activity Detector)와 CNG(Comfort Noise Generator)를 사용하고 있다 이중 VAD는 최종적으로 현재 프레임의 에너지 레벨을 비교하여 음성의 활동 유무를 판정하고 있다. 하지만 G.723.1 VAD에서는 보다 안정적인 판정을 위해 음성 활동 구간 사이에 삽입되어 있는 묵음 구간에 대해서는 거의 대부분 음성이 활동하는 영역으로 판정을 하고 있다. 따라서 본 논문에서는 묵음 구간에 대해 보다 정확한 판정을 통하여 기존의 방법에 비해 전송율을 더욱 감소시킬 수 있는 방법을 제안한다. 실험에서는 묵음구간을 길게 조절한 문장을 사용하여 측정한 결과 평균 $46.8\%$ 정도의 전송율을 감소시킬 수 있었으며, 주관적인 음질평가의 경우 음질의 열하는 거의 발생하지 않았다.

• Journal of Korea Multimedia Society
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• v.6 no.1
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• pp.67-77
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• 2003

Watermark detection has a crucial role in copyright protection and authentication for multimedia Because be the correlation -based algorithm which has widely been used in the watermark detection doesn't utilize the distributional characteristics of cover image to be marked, its performance is not optimum. So a new detection algorithm is proposed which is optimum for multiplicative watermark embedding. By relying on statistical decision method, the proposed method is derived according to the Bayes decision theory. Neyman Pearson criterion, and distribution of wavelet coefficients, thus Permitting to minimize the missed detection probability subject to a given false detection probability The superiority of the proposed method has been tested from a robustness perspective. The results confirm the superiority of the proposed technique over classical correlation -based method.

• Microbiology and Biotechnology Letters
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• v.14 no.2
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• pp.133-137
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• 1986

17S-ribosomal RNA gene from the hygromycin resistant protozoan Tetrahymena thermophila hmr 3 was cloned on E. coli vector pBR 322 as part of study to work the 17S-rRNA structure and the mechanism of hygromycin resistance. The 17S-rDNA was inserted into the Hind 111 site of pBR 322. The clones having recombinant plasmid were selected by the method of colony hybridization with a 17S-rDNA probe of wild type B1868. The orientation of 17S-rDNA insert was located near the tetracycline resistant gene of pBR 322 in a clone 5-19 with the recombinant plasmid.

• Journal of the Korean Arthroscopy Society
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• v.9 no.1
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• pp.56-59
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• 2005

Trans-posterior septal posterior arthroscopic portals are useful in performing arthroscopic diagnosis and treatment of the lesions located in posterior aspect of knee joints. Except inferior surface of posterior horn of lateral meniscus, we easily observed entire lateral compartment, especially inferior surface of anterior horn and lateral tibial condyle by figure of 4 position through posteromedial trans-posterior septal arthroscopic portal. And it was possible to obtain visual field from posterior aspect and we could use anteromedial and anterolateral portals for instrumentation without clouding. So, this procedure may be useful in performing surgery of lateral compartment especially, anterior aspect in the knee joints.

• The Journal of Korean Society for Radiation Therapy
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• v.7 no.1
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• pp.45-53
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• 1995

목적 : 뇌정위 방사선수술은 AVM(ateriovenous malformation)이나 작은 크기의 종양에 1회에 고선량의 방사선을 조사하는 기술이다. 선형가속기를 이용한 방사선 수술을 하기 위하여 최근 본원에 설치한 Philips SL 75-5 선형가속기와 isocentric sub system(ISS)에 의한 뇌정위 방사선 수술에 있어서 표적의 위치선정과, gantry와 couch의 회전시 기하학적 오차가 중요시 되는데 isocentric sub system의 오차를 분석 하였다. 대상 및 방법 : 방사선원으로는 Philips SL 75-5 선형가속기의 5MV 광자선을 사용하였고, 원형의 작은 광자선속을 위하여 isocenter에서의 직경이 26mm인 secondary cone을 gimbal baaring에 삽입하여 사용하였다. 표적의 크기와 좌표를 정하기 위하여 CT나 angio localizer를 이용하고, 표적좌표 선정을 위하여 BRW phantom base와 target pointer를 이용하여 임의의 BRW-coordinator를 바꾸어 가면서 gantry angle와 ISS head 각도를 임의로 바꾸어 가면서 film에 방사선을 조사하였다. 흑화된 film을 view box 위에 놓고 광학판독기구로 film 가장자리의 오차를 scale 확대경으로 측정하여 오차를 분석하였다. 결과 : 표적좌표 선정의 정확도를 확인하기 위하여 임의의 표적좌표에 gantry의 10개각도 ISShead의 10개각도에서 각각 광자선을 조사시켜 film을 이용하여 오차를 측정한 결과 collimator cone의 직경이 26mm일때 전체 평균오차가 0.219+-0.03mm이었다. 결론 : Isocentric sub system은 gantry head와 ISS arm 사이에 gimbal bearing이 있어서 이 부위를 flexible하게 연결함으로 gantry의 회전에 무관하게 정확한 isocenter를 유지시켜 주고 ISS head는 couch와 독립되어 움직이므로 isocentric sub system isocenter의 오차를 최대한 줄일수 있음을 알았다.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.30 no.12 s.255
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• pp.1509-1517
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• 2006

The intervertebral fusion was reported to increase the degeneration of the neighboring region. Recently, a new technique of inserting an interspinous process fixator has been introduced to minimize the degenerative change in the lumbar spine. This study analyzed biomechanical effects of the fixator in the lumbar spine, and designed a new prototype to improve flexibility of the fixator with a reduced size. The evaluation was based on the displacement, stiffness and von-Mises stress obtained from the mechanical test and finite element analysis. A finite element lumbar model of L1 to L5 was constructed. The finite element model was used to analyze intervertebral fusion, insertion of a commercial fixator and a new prototype. The range of motion of intervertebral segments and pressures at vertebral discs were calculated from FEA. The results showed that the stiffness of the prototype was reduced by 32.9% than that of the commercial one.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.244-244
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• 2010

최근 활발히 연구되고 있는 AMOLED는 평판 디스플레이 분야를 이끌어 갈 차세대 선두 주자로 크게 주목 받고 있다. AMOLED는 전압 구동 방식인 AMLCD와 다르게 전류 구동 방식으로 a-Si TFT 보다 LTPS-TFT 사용이 요구되며, 대면적 기판으로 갈수록 결정립의 균일도가 매우 중요한 인자로 작용한다. 현재 양산이 가능한 AMOLED는 핸드폰이나 15인치 TV정도로 크기가 소형이며 대형 TV나 컴퓨터 모니터 등을 양산하기 위해 많은 방법이 시도되고 있다. 양산체제에서 사용되는 결정화 방법으로는 ELC가 가장 많은 부분을 차지하고 있다. 그러나 레이저를 사용하는 ELC 방법은 대면적으로 갈수록 레이저 빔 자체의 불균일성, shot to shot 불균일성, 레이저빔 중첩의 부정확도 등으로 인한 균일도의 부정확성이 커짐으로 인한 mura 현상이 나타나고 레이저 장비의 사용에 대한 비용 부담을 피할 수 없다. 따라서 non-laser 방식에 결정화 방법이 요구되나 SPC 경우는 상대적으로 고온에서 장시간이 걸리고, MIC 뿐만 아니라 MIC 응용 방법들은 금속 오염에 대한 문제가 발생하고 있는 실정이다. 이러한 문제로 인하여 결정립 크기의 균일도가 우수한 다결정 실리콘 박막을 제조하는 신기술에 대한 필요성이 매우 높은 실정이다. 본 연구에서는 비정질 실리콘 박막 상부 혹은 하부에 도전층을 개재하고, 상기 도전층에 전계를 인가하여 그것의 주울 가열에 의해 발생한 고열로 비정질 실리콘 박막을 급속 고온 고상 결정화하는 방법에 관한 기술인 JIC (Joule-heating Induced Crystallization) 결정화 공정을 개발하였다. 본 공정은 상온에서 수 micro-second 내에 결정화를 수행하는 것이 가능하며 도전층과 실리콘 박막 사이에 barrier층 삽입를 통하여 금속 오염을 막을 수 있으며 공정적인 측면에서도 별도의 chamber가 필요하지 않는 장점을 가지고 있다. 본 논문에서는 JIC 결정화 공정 조건에 따른 결정화 기구 및 JIC poly-Si의 미세구조 및 물리적 특성에 관한 논의가 이루어질 것이다.

• Radiation Oncology Journal
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• v.26 no.3
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• pp.189-194
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• 2008

Purpose: We designed a water-based bolus device for radiation therapy in Kaposi's sarcoma. This study evaluated the usefulness of this new device and compared it with the currently used rice-based bolus. Materials and Methods: We fashioned a polystyrene box and cut a hole in order to insert patient's extremities while the patient was in the supine position. We used a vacuum-vinyl based polymer to reduce water leakage. Next, we eliminated air using a vacuum pump and a vacuum valve to reduce the air gap between the water and extremities in the vacuum-vinyl box. We performed CT scans to evaluate the density difference of the fabricated water-based bolus device when the device in which the rice-based bolus was placed directly, the rice-based bolus with polymer-vinyl packed rice, and the water were all put in. We analyzed the density change with the air gap volume using a planning system. In addition, we measured the homogeneity and dose in the low-extremities phantom, attached to six TLD, and wrapped film exposed in parallel-opposite fields with the LINAC under the same conditions as the set-up of the CT-simulator. Results: The density value of the rice-based bolus with the rice put in directly was 14% lower than that of the water-based bolus. Moreover, the value of the other experiments in the rice-based bolus with the polymer-vinyl packed rice showed an 18% reduction in density. The analysis of the EDR2 film revealed that the water-based bolus shows a more homogeneous dose plan, which was superior by $4{\sim}4.4%$ to the rice-base bolus. The mean TLD readings of the rice-based bolus, with the rice put directly into the polystyrene box had a 3.4% higher density value. Moreover, the density value in the case of the rice-based bolus with polymer-vinyl packed rice had a 4.3% higher reading compared to the water-based bolus. Conclusion: Our custom-made water-based bolus device increases the accuracy of the set-up by confirming the treatment field. It also improves the accuracy of the therapy owing to the reduction of the air gap using a vacuum pump and a vacuum valve. This set-up represents a promising alternative device for delivering a homogenous dose to the target volume.

• Journal of Chest Surgery
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• v.36 no.2
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• pp.63-72
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• 2003

Although a variety of synthetic vascular grafts are available in modern vascular surgery, no ideal prosthesis ha,4 yet been developed. Small-caliber vascular grafts with low flow, as used in the lower extremity, continue to become thrombosed at unacceptable rates. We have developed and evaluated the new antithrombogenic blood contacting surfaces in canine model. Material and Method: Two now antithrombogenic blood contacting surfaces(Polyvinylalcohol -Polyurethane(PVA-PU) blend and natural Graphite-polyurethane(G-PU) blend) have been developed and evaluated in canine model, using vascular grafts and patches. The luminal surfaces of the test vascular grafts(5 mm ID) were fabricated by dipping a glass rod in PVA-PU blend solution(50 % PVA) using phase separation method. Mongrel dogs of either sex weighing 18-22 kg were anesthetized by endotracheal intubation using halothane and their lungs were ventilated with a volume-cycled ventilator, Maintenance anesthesia with 0.5-1.0% halothane and supplemental oxygen was used. Two pairs were used for comparison in the bilateral femoral arteries for both vascular grafts(PVA-PU vs. PU) and vascular patches(G-PU vs. PU). Bilateral groin incisions were made and the arteries were exposed and clamped. After an excision of 1 cm of the artery between clamps, a grail of 2.5 cm in length was implanted end-to-end using 6-0 polypropylene suture. The vascular patch was implanted as a form of on-lay patch. Animals were sacrificed at 1, 2, 4, 6, 8 and 16 weeks for vascular grafts and 1, 2. 4 and 6 weeks for vascular patches. Result The vascular grafts of PVA-PU blends showed patent lumina in the 2 and 16 weeks animals, while those of PU showed a patent lumen in 2 weeks animal. PVA-PU graft of 16 weeks showed a fairly clean luminal surface. A light microscopic finding of this graft demonstrated good tissue infiltration through porosity, The animals with vascular patches showed patent arteries in both groups except 2 weeks animal. Scanning electron microscopy of the luminal surfaces of G-PU patches in 4 and 6 weeks animals showed endothelial cell covering with microvilli. PU patches showed qualitatively less endothelial cell covering. Conclusion: In conclusion, PVA-PU and G-PU blends can be a promising blood contacting surfaces for application in a synthetic vascualr graft. However, further animal study is needed to determine the real long-term effects of these methods of surface modifications.

• Journal of the Korean Wood Science and Technology
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• v.44 no.1
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• pp.30-39
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• 2016

The evaluation of the lateral load performance for larch glulam portal frames was carried out using glass fiber reinforced plastic (GFRP) as connector in two different systems: the GFRP-reinforced laminated plates combined with veneer, and GFRP rod joints glued with epoxy resins to replace usual metal connectors for the structural glulam rahmen joints. As a result the yield strength, ultimate strength, initial stiffness of glulams of GFRP rod joints glued with epoxy resin decreased to 49%, 52% and 61% compared to those of the conventional metal connector. This connector will be a stress device where the bonding strength between the GFRP rod and glued laminated timber is important. Thus, there will be a high possibility that a problem may occur when it is applied to the field. On the other hand, the GFRP-reinforced laminated plates and wood (Eucalyptus marginata) pin were measured all within 3% for all measurements of the yield strength, ultimate strength, initial strength and ductility factor, regardless of high cross sectional loss on the glued laminated timber slit joint. In addition, the variation of stiffness on the cycle was 35%, which was the lowest, confirming that it was almost the same performance as the specimen prepared with the metal connector.