• 한국전기전자재료학회논문지
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• 제24권1호
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• pp.32-35
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• 2011

Top-emission device has a merit of high aperture ratio and narrow emission spectrum compared to that of bottom-emission one. Emission spectra of top-emission organic light-emitting diodes depending on a layer thickness and view angle were analyzed using a theory of microcavity. Device structure was manufactured to be Al (100 nm)/TPD/$Alq_3$/LiF (0.5 nm)/Al (2 nm)/Ag (30 nm). N,N'-diphenyl-N,N'- di (m-tolyl)-benzidine (TPD) and tris (8-hydroxyquinoline) aluminium (Alq3) were used as a hole-transport layer and emission layer, respectively. And a thickness of TPD and Alq3 layer was varied in a range of 40 nm~70 nm and 60 nm~110 nm, respectively. Angle-dependent emission spectrum out of the device was measured with a device fixed on a rotating plate. Since the top-emission device has a property of microcavity, it was observed that the emission spectrum shift to a longer wavelength region as the organic layer thickness increases, and to a shorter wavelength region as the view angle increases. Layer thickness and view-angle dependent emission spectra of the device were analyzed in terms of microcavity theory. A reflectivity of semitransparent cathode and optical path length were deduced.

• 반도체디스플레이기술학회지
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• 제16권2호
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• pp.44-48
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• 2017

We explain optical and electrical properties of top and bottom-emission structured alternating-current powder electroluminescent devices (ACPELDs) with Ga-doped ZnO(GZO) transparent electrode. The top-emission ACPELDs were layered as the metal electrode/dielectric layer/emission layer/top transparent electrode and the bottom-emission ACPELDs were structured as the bottom transparent electrode/emission layer/dielectric layer/metal electrode. The yellow-emitting ZnS:Mn, Cu phosphor and the barium titanate dielectric layers were layered through the screen printing method. The GZO transparent electrode was deposited by the sputtering, its sheet resistivity is $275{\Omega}/{\Box}$. The transparency at the yellow EL peak was 98 % for GZO. Regardless of EL structures, EL spectra of ACPELDs were exponentially increased with increasing voltages and they were linearly increased with increasing frequencies. It suggests that the EL mechanism was attributed to the impact ionization by charges injected from the interface between emitting phosphor layer and the transparent electrode. The top-emission structure obtained higher EL intensity than the bottom-structure. In addition, charge densities for sinusoidal applied voltages were measured through Sawyer-Tower method.

• Journal of the Optical Society of Korea
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• 제14권3호
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• pp.277-281
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• 2010

We propose a design and optimization method for a dielectric-loaded surface plasmon polariton waveguide using a genetic algorithm. This structure consists of a polymer ridge on top of two layers of substrate and gold film. The thickness, width and refractive index of the ridge are designed to optimize the figures of merit including mode confinement and propagation length. The modal analysis combined with the effective index method shows that the designed waveguide exhibits a fundamental propagation mode with high mode confinement while ensuring that the propagation loss remains relatively low.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1987년도 전기.전자공학 학술대회 논문집(I)
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• pp.98-100
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• 1987

A granite optical table with a vibration isolator system is designed and constrvcted. The table top is made with granite and the vibration isolation system is constrvcted using a pneumatic isolator. The performance of the table is evalvated by the vibration measurement.

• 한국광학회:학술대회논문집
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• 한국광학회 1989년도 제4회 파동 및 레이저 학술발표회 4th Conference on Waves and lasers 논문집 - 한국광학회
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• pp.185-192
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• 1989

It is shown that GaAs/GaAs stripe Roof-Top-Reflector LD is better than cleaved mirror LD by numerical analysis. And surface light emitting device is developed by LPE melt-back growth, which is of good controllability for OEIC. OEIC transmitter using RTR LD structured device and FET has been made and modulated, expected to show good modulation characteristics after solving process problem. Beam-Lead LD mounted on Si carrier has been made and shows low heat-resistance and so long life and good characteristics of LD.

• 소성∙가공
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• 제17권5호
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• pp.322-327
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• 2008

LGP is a key component of LCD back light unit because it determines brightness and sharpness of the display image. Usually, it has optical patterns fabricated on the bottom surface. These optical patterns convert point or line sources placed in the side of LGP to plane source at the top surface by changing the propagating direction of the incident light. In the present paper the LiGA-reflow method was applied to fabricate the LGP mold. Furthermore, the optical simulation considering the replication ratio of pattern height was applied to the pattern design. The optical simulation through systematic correction scheme was adopted to find the optimum distribution of pattern density. Finally, the stamper fabricated by this method was installed in the mold and LGP was produced by injection molding. As a result of luminance measurement for the final product, the average luminance and luminance uniformity was measured 3,180 nit and 84%, respectively. Consequently, the mold fabrication method using the LiGA-reflow and optical simulation(CAE) can save the expense and time compared with the existing fabrication methods(laser ablation and chemical etching).

• Current Optics and Photonics
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• 제1권2호
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• pp.113-117
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• 2017

With the increasing use of high-power laser diode bars (LDBs) and stacked LDBs, the issue of thermal control has become critical, as temperature is related to device efficiency and lifetime, as well as to beam quality. To improve the thermal resistance of an LDB set, we propose and analyze a bypass heat sink with a top canopy structure for an LDB set, instead of adopting a thick submount. The thermal bypassing in the top-canopy structure is efficient, as it avoids the cross-sectional thermal saturation that may exist in a thick submount. The efficient thickness range of the submount in a typical LDB set is guided by the thermal resistance as a function of thickness, and the simulated bypassing efficiency of a canopy is higher than a simple analytical prediction, especially for thinner canopies.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2012년도 제42회 동계 정기 학술대회 초록집
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• pp.440-440
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• 2012

The optical characteristics of transparent electrode with various kind of materials and thickness to be used for organic photovoltaic cells were studied by simulation methodology. It demonstrated that the transmittance varies with the kinds of materials, the number of layers and change in the thickness of each layer. In the case of the structure composed of dielectric/Ag/dielectric, optimized transmittance was higher than 90% at 550 nm and the thickness of the Ag layer was ~10nm. Top and bottom dielectric materials can be changed with different refractive index and extinction coefficient. The relation between the optical transmittance of device and transparent electrode with different refractive indices was discussed as well. By processing numerical simulations, an optimized optical transmittance can be obtained by tunning the thickness and materials of transparent electrode.

• 한국정밀공학회지
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• 제31권5호
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• pp.417-422
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• 2014

A guitar pickup is a transducer that converts string vibration to an electrical signal. The magnetic and piezo pickups are the most commonly used for the respective electric and electroacoustic guitars. The magnetic pickups are prone to magnetic interference between the steel strings and permanent magnets, while the piezo ones are not free from signal inference between the strings. Thus, this paper presents the development of an optical pickup for the electroacoustic guitar. The proposed optical pickup has the top-to-bottom structure. It uses two of Infrared (IR) Light Emitting Diode (LED) and one photodetector. The developed optical pickup is subjected to the evaluation with commonly used piezoelectric pickup. It becomes obvious that SNR with the optical pickup is increased by 45 percent in average, compared with the piezoelectric pickup. It can be concluded that the developed optical pickup has a potential to be applied to the acoustic guitar.

• 스마트미디어저널
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• 제11권1호
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• pp.46-57
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• 2022

본 논문에서는 딥러닝을 기반으로 입력영상의 옵티컬 플로우(optical flow)와 그래디언트(gradient)를 이용하여 종단간 행동인식이 가능한 다중영역 기반 방사성 GCN(MRGCN: Multi-region based Radial Graph Convolutional Network) 알고리즘에 대해 기술한다. 이 방법은 데이터 취득이 어렵고 계산이 복잡한 스켈레톤 정보를 사용하지 않기 때문에 카메라만을 주로 사용하는 일반 CCTV 환경에도 활용이 가능하다. MRGCN의 특징은 입력영상의 옵티컬플로우와 그래디언트를 방향성 히스토그램으로 표현한 후 계산량 축소를 위해 6개의 특징 벡터로 변환하여 사용한다는 것과 시공간 영역에서 인체의 움직임과 형상변화를 계층적으로 전파시키기 위해 새롭게 고안한 방사형 구조의 네트워크 모델을 사용한다는 것이다. 또 데이터 입력 영역을 서로 겹치도록 배치하여 각 노드 간에 공간적으로 단절이 없는 정보를 입력으로 사용한 것도 중요한 특징이다. 30가지의 행동에 대해 성능평가 실험을 수행한 결과 스켈레톤 데이터를 입력으로 사용한 기존의 GCN기반 행동인식과 동등한 84.78%의 Top-1 정확도를 얻을 수 있었다. 이 결과로부터 취득이 어려운 스켈레톤 정보를 사용하지 않는 MRGCN이 복잡한 행동인식이 필요한 실제 상황에서 더욱 실용적인 방법임을 알 수 있었다.