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포토리소그래피를 통한 광통신용 실리콘 렌즈 제작 및 특성 연구
박준성,이대장,노호균,김성근,허재영,류상완,강성주,하준석 한국마이크로전자및패키징학회 2018 마이크로전자 및 패키징학회지 Vol.25 No.2
In order to improve the coupling efficiency, a collimator lens that collects the light emitted from the laser diode at a wide angle to the core of the optical fiber is essential. Glass mold method using a mold is widely used as a collimator lens currently used. Although this method is inexpensive to produce, it is difficult to form precisely and quality problems such as spherical aberration. In this study, the precision of surface processing was improved by replacing the existing glass mold method with the semiconductor process, and the material of the lens was changed to silicon suitable for the semiconductor process. The semiconductor process consists of a photolithography process using PR and a dry etching process using plasma. The optical coupling efficiency was measured using an ultra-precision alignment system for the evaluation of the optical characteristics of the silicon lens. As a result, the optical coupling efficiency was 50% when the lens diameter was 220 μm, and the optical coupling property was 5% or less with respect to the maximum optical coupling efficiency in the lens diameter range of 210-240 μm. 광결합 효율(Fiber coupling efficiency)을 개선하기 위해서는 Laser diode에서 넓은 각도로 방출된 빛을 광섬유의 중심(Core) 부분으로 모아주는 집광렌즈(Collimating lens)가 필수적이다. 현재 사용되는 집광렌즈는 형틀(Mold)을이용한 글래스 몰드(Glass mold) 공법이 널리 사용되고 있다. 이 방식은 생산단가가 저렴하지만, 정교한 성형이 어렵고구면수차와 같은 품질문제가 있다. 본 연구는 기존의 글래스 몰드 공법을 반도체 공정으로 대체함으로써 표면 가공의 정밀도를 높이고, 렌즈의 재질 또한 반도체 공정에 적합한 실리콘으로 변경하였다. 반도체공정은 PR을 이용한 포토리소그래피(Photolithography) 공정과 플라즈마를 이용한 건식 식각(Dry etching) 공정으로 구성된다. 광결합 효율은 실리콘 렌즈의 광학적 특성을 평가하기 위해 초정밀 정렬 시스템을 사용하여 측정되었다. 그 결과, 렌즈 직경 220 μm 일 때의 최대 광결합 효율은 50%로 측정되었고, 렌즈 직경 210-240 μm 범위에서는 최고 광결합 효율 대비 5% 이하의 광결합 특성저하를 보여줌을 확인하였다.
전완 골절 후 도수 정복 시 골절 부위 간격에 따른 골절 인접 연부 조직의 생체역학적 특성 평가: 유한요소해석
박준성,이상현,송찬희,노정훈,이치승,Park, Jun-Sung,Lee, Sang Hyun,Song, Chanhee,Ro, Jung Hoon,Lee, Chiseung 대한의용생체공학회 2022 의공학회지 Vol.43 No.5
The purpose of this study is to evaluate the biomechanical properties of fractured adjacent soft tissue during closed reduction after forearm fracture using the finite element method. To accomplish this, a finite element (FE) model of the forearm including soft tissue was constructed, and the material properties reported in previous studies were implemented. Based on this, nine finite element models with different fracture types and fracture positions, which are the main parameters, were subjected to finite element analysis under the same load and boundary conditions. The load condition simulated the traction of increasing the fracture site spacing from 0.4 mm to 1.6 mm at intervals of 0.4 mm at the distal end of the radioulnar bone. Through the finite element analysis, the fracture type, fracture location, and displacement were compared and analyzed for the fracture site spacing of the fractured portion and the maximum equivalent stress of the soft tissues adjacent to the fracture(interosseous membrane, muscle, fat, and skin). The results of this study are as follows. The effect of the major parameters on the fracture site spacing of the fractured part is negligible. Also, from the displacement of 1.2 mm, the maximum equivalent stress of the interosseous membrane and muscle adjacent to the fractured bone exceeds the ultimate tensile strength of the material. In addition, it was confirmed that the maximum equivalent stresses of soft tissues(fat, skin) were different in size but similar in trend. As a result, this study was able to numerically confirm the damage to the adjacent soft tissue due to the fracture site spacing during closed reduction of forearm fracture.
제2형 당뇨병 환자의 말초 혈관 질환의 위험 인자에 관한 연구
박준성,강준구,함준수,강종명,유원섭,박충기,안유헌 대한혈관외과학회 2002 Vascular Specialist International Vol.18 No.2
Purpose: Peripheral artery disease (PAD) is thought one of the most serious complications caused by atherosclerosis, and the principle cause of death and disability in persons age 50 years or older. But, there is very little information on the prevalence of PAD in diabetic patients and relationship between risk factors and PAD in Korea. Thus, the authors conducted this study to find the risk factors for PAD in diabetic patients and help to improve patients' health. Method: A total of 149 Korean NIDDM patients were enrolled. All subject's systolic blood pressures in arm and ankle were measured with a Doppler ultrasonic instrument, from which ankle-brachial pressure index (ABPI) was derived. We also examined clinical and biochemical parameters in all patients. Result: Systolic pressure, total cholesterol, TG, LDL were higher and albumin were lower in diabetic patients with PAD than in diabetic patients without PAD (p value <0.01). Logistic regression analysis showed that hypoalbuminemia and hypertrigly-ceridemia were independent risk factor of PAD. Conclusion: In the light of these results, it seems reasonable to suggest that hypoalbuminemia and hypertriglyceridemia in diabetic patients may play a role in the pathogenesis of PAD.