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LCD 백라이트용 렌티큘라 렌즈필름의 광구조 최적화에 관한 연구
서재석,고재현,Seo, Jae-Seok,Ko, Jae-Hyeon 한국광학회 2011 한국광학회지 Vol.22 No.6
최근 확산기능과 집광기능을 동시에 가지는 복합필름에 대한 관심이 커지고 있다. 본 시뮬레이션연구에서는 복합필름으로 주목 받고 있는 렌티큘라 렌즈필름의 광학구조를 최적화하고 이를 기존의 백라이트가 보이는 광학 성능과 비교하였다. 보다 정확한 시뮬레이션의 수행을 위해 시험적으로 제작된 렌티큘라 렌즈필름이 보이는 휘도의 시야각 분포를 측정하였고 이 실험 결과를 재현할 수 있는 시뮬레이션 조건, 특히 도광판의 산란 패턴이 가지는 쌍방향 산란분포함수의 수학적 모델을 확보하였다. 이에 근거해서 시뮬레이션을 수행한 결과 렌티큘라 렌즈의 종횡비가 1.25, 굴절률이 1.65인 조건에서 이 필름의 집광성능이 최대가 됨을 확인하였다. 최적화된 렌티큘라 렌즈필름이 1매 포함된 백라이트 모델은 프리즘필름이 1매 포함된 기존의 백라이트에 비해 집광성능이 현저히 떨어졌지만 렌티큘라 렌즈필름 2매를 직교해서 적용하게 되면 프리즘필름 1매가 가지는 집광 성능과 비슷한 성능을 달성함과 동시에 부드러운 시야각 특성의 구현에 기여할 수 있다는 점을 확인하였다. The optical performance of LLF(Lenticular Lens Film)-based backlight was studied by using optical simulation as functions of the aspect ratio and the refractive index of lenticular lenses. In order to perform reliable simulation, the BSDF(bi-directional scattering distribution function) of the scattering dots on the bottom surface of the light guide plate was obtained as a superposition of the Lambertian and the elliptic Gaussian distribution components by comparing the experimental results and the simulation for the luminance distribution on the light guide. Based on this approach, an appropriate BSDF of the scattering dots of the light guide was constructed. The resultant values of the optimized aspect ratio and the refractive were found to be 1.25 and 1.65, respectively. In spite of the hybrid aspects of LLF incorporating both diffusing and collimating functions, the optical performance, in particular the on-axis luminance of LLF-based backlight was inferior by about 20% compared to that of conventional backlights adopting one prism film. However, the combination of two lenticular lens films resulted in comparable luminance gain as well as smooth decrease in the luminance with the viewing angle without exhibiting any side lobes.
중수로 압력관 및 피더관 국부 감육의 응력집중계수에 관한 연구
서재석(Jae Seok Seo),김종성(Jong Sung Kim) 대한기계학회 2010 대한기계학회 춘추학술대회 Vol.2010 No.11
In this study, stress concentration factors of the various local wall thinning in CANDU feeder pipe and pressure tube are calculated by using finite element analysis. The feeder pipes made of SA-106 Grade B carbon steel have some elbows and bends. An active degradation mechanism for the carbon steel outlet feeder piping is local wall thinning due to flow-accelerated corrosion. This local wall thinning can cause increase of peak stress due to stress concentration by notch effect. The pressure tube were made zirconum alloy. This study investigates the effect of local wall thinning geometry on stress concentration by performing finite element elastic stress analysis.
서재석 ( Jae Seok Seo ),이응갑 ( Eung Kap Lee ),오종택 ( Jong Taek Oh ),김철태 ( Cheol Tae Kim ) 대한내과학회 2010 대한내과학회지 Vol.79 No.4
Congenital carpal coalition is an uncommon anomaly that results from an incomplete joint cavitation of the primitive carpus. Congenital carpal coalition between the capitate and hamate is generally believed to be asymptomatic and, thus, is usually discovered on radiographs taken for unrelated reasons. We report two cases of congenital carpal coalition (capitate-hamate) associated with pain of the wrist. (Korean J Med 79:457-460, 2010)
나노 은 콜로이드 입자의 안정성에 대한 $NaBH_4$ 및 Laponite의 영향
이정백,김동환,서재석,김유혁,Lee, Jung-Baek,Kim, Dong-Hwan,Seo, Jae-Seok,Kim, You-Hyuk 한국결정성장학회 2006 한국결정성장학회지 Vol.16 No.6
본 연구에서는 수용액에서 화학적 환원 방법을 사용하여 나노미터 수준의 은을 합성하는데 있어서 입자크기 및 응집에 영향을 줄 수 있는 $NaBH_4$의 농도, 반응 온도, 반응물 첨가속도 및 laponite의 농도에 대하여 연구하였다. laponite가 없는 조건하에서는 $NaBH_4/AgNO_3$의 몰 비가 3일 때 안정한 나노 은 졸이 형성되었으며 또한 환원반응의 온도가 증가 할수록 은 입자의 평균 크기는 증가하였다. 또한 $AgNO_3$의 첨가속도가 빠르면 초기반응단계에서 형성된 높은 농도의 은 입자들이 응집되어 입자크기가 큰 나노 은이 생성됨을 보여 주고 있다. 보호층 콜로이드로 laponite를 사용하였을 때 고온 $(>\;100^{\circ}C)$에서 안정한 나노 은 졸을 합성할 수 있었다. The synthesis and characterization of silver colloidal nanoparticles by chemical reduction of silver ions in aqueous $AgNO_3$ using sodium borohydride $(NaBH_4)$ as the reducing agent are described. The experimental conditions for aggregation and paricle size of nanosilver particles in water is investigated in terms of concentration of $NaBH_4$, reaction temperature, dropping rate of $AgNO_3$ and concentration of laponite. Stable nanosilver sol is obtained at three molar ratio of $NaBH_4/AgNO_3$ in conditions of without laponite. The size of nanosilver particles is increased as the reaction temperature is increased. The large size of nanosilver sol is obseved as the dropping rate of $AgNO_3$ is increased due to the aggregation of initial high local concentration of nanosilver particles. Stable nanosilver sol at high temperature $(>\;100^{\circ}C)$ can be prepared when laponite is used as protective colloid.
김건우 ( Gun Woo Kim ),서재석 ( Jae Seok Seo ),한승우 ( Seung Woo Han ),강영모 ( Young Mo Kang ) 대한류마티스학회 2003 대한류마티스학회지 Vol.10 No.4
Protein losing enteropathy (PLE) is characterized by the loss of protein into the gastrointestinal tract that results in hypoalbuminemia and generalized edema. PLE is associated with several clinical disorders, but it is a rare manifestation of systemic lupus erythematosus (SLE), and it may be the presenting manifestation of SLE. We report a patient with SLE presenting with PLE, in whom methylprednisolone pulse therapy was highly effective. A 29-year-old women was admitted to our hospital with generalized edema. Laboratory findings revealed hypoalbuminemia, hypercholesterolemia and antinuclear antibody 1:160, speckled type. Mucosal biopsies of the duodenal bulb and terminal ileum revealed edema and dilated lymphatics with infiltration of chronic inflammatory cells. PLE was diagnosed by marked elevation of alpha-1 antitrypsin clearance in stool and abnormal radioactivity within small intestine on 99mTc-labeled human serum albumin scan. Hypoalbuminemia and generalized edema improved rapidly after methylprednisolone pulse therapy.
중수로 피더관 국부 감육의 응력집중계수에 미치는 굽힘 각도의 영향 고찰
김종성(Jong Sung Kim),서재석(Jae Seok Seo) 대한기계학회 2010 대한기계학회 춘추학술대회 Vol.2010 No.4
In this study, stress concentration factors of the various lcoal wall thinnings in CANDU feeder pipe are calculated by using finite element analysis. In particular, the effect of bending angle on the stress concentration factor is investigated via the parametric study considering variations of local wall thinning depth and location, and bending angle. As a result of the investigation, it is identified that the effect of bending angle is insignificant for the feeder pipe with local wall thinning under internal pressure.