• Current Optics and Photonics
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• 제3권6호
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• pp.590-596
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• 2019

To improve the color gamut of a liquid-crystal display (LCD), we propose a bandpass filter that is added to the backlight unit to optimize the backlight spectrum. The bandpass filter can only transmit red, green and blue light in the visible range, while reflecting the unwanted light. We study the optical properties of the bandpass filter using the transfer-matrix method, and the effect of the bandpass filter on the color gamuts of LCDs is also investigated. When a bandpass filter based on a 5-layer configuration comprising low and high refractive indices ((HL)²H) is used in phosphor-converted white-light-emitting diode (pc-WLED), K₂SiF₆:Mn⁴⁺ (KSF-LED), and quantum-dot (QD) backlights, the color gamuts of the LCDs improve from 72% to 95.3% of NTSC, from 92% to 106.7% of NTSC, and from 104.3% to 112.2% of NTSC respectively. When the incident angle of light increases to 30°, the color gamuts of LCDs with pc-WLED and KSF-LED backlights decrease by 2.9% and 1% respectively. For the QD backlight, the color gamut almost does not change. When the (HL)²H structure is coated on the diffusion film, the color gamut can be improved to 92.6% of NTSC (pc-WLED), 105.6% of NTSC (KSF-LED), and 111.9% of NTSC (QD). The diffusion film has no obvious effect on the color gamut. The results have an important potential application in wide-color-gamut LCDs.

• 마이크로전자및패키징학회지
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• 제13권3호
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• pp.13-17
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• 2006

밀도가 높고 주기적인 배열의 기공과 나노패턴이 된 텅스텐 나노점이 실리콘 산화물/실리콘 기판위에 형성이 되었다. 기공의 지름은 25 nm이고 깊이는 40 nm 이었으며 기공과 기공 사이의 거리는 60 nm이었다. nm 크기의 패턴을 형성시키기 위해서 자기조립물질을 사용했으며 폴리스티렌(PS) 바탕에 벌집형태로 평행하게 배열된 실린더 모양의 폴리메틸메타아크릴레이트(PMMA)의 구조를 형성했다. 폴리메틸메타아크릴레이트를 아세트산으로 제거하여 폴리스티렌만 남아있는 건식 식각용 마스크를 만들었다. 실리콘 산화막은 불소 기반의 화학반응성 식각법을 이용하여 식각했다. nm크기의 트렌치 안에 선택적으로 증착된 텅스텐 나노점을 만들기 위해서 저압화학기상증착(LPCVD)방법을 이용하였다. 텅스텐 나노점과 실리콘 트렌치의 지름은 26 nm 와 30 nm였다.

• 한국인터넷방송통신학회논문지
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• 제16권1호
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• pp.129-137
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• 2016

전송계층 프로토콜처럼 전송제어 프로토콜은 안정적인 데이터 전송 서비스를 제공한다. 다양한 네트워크에서 TCP의 성능을 저해하는 일부 심각한 문제가 있다. TCP 네트워크 환경에서 중요한 문제는 빠른 전송 속도로 인해 또는 동시에 네트워크로 접속하는 다수의 새로운 접속으로 인하여 발생하는 혼잡이다. 그러므로 라우터에서 큐의 크기는 패킷 하락에 기인하여 증가한다. 손실된 패킷의 재전송과 감소된 처리량은 많은 비용을 발생시킨다. RED처럼 AQM과 ECN은 패킷 하락 보다는 패킷 마킹에 사용된다. IP 패킷 헤더에서 ECN 비트는 불필요한 패킷 하락을 피하기 위한 혼잡 표시로 추가할 수 있다. 제안하는 ECN과 AQM 메커니즘은 NS2 시뮬레이터의 도움으로 구현할 수 있으며, 그 성능은 다른 TCP 변종에서 테스트할 수 있다.

• 한국지열·수열에너지학회논문집
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• 제2권1호
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• pp.1-7
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• 2006

This paper was studied for optimum design of the used vaporizer at a satellite station. Generally, the cold air is created by temperature drop on the vaporizer surface. In addition, the frost creates ice deposit layer, therefore, heat transfer on vaporizer decreases into the adiabatic condition. By this reason, recent vaporizer system is installed as parallel type, and it takes three times of vaporizer capacity. But this vaporizer system requires much installation costs and restricted by some space. It is very important to solve this problem. This study paper is regarding $LN_2$ vaporizer where the utilization increases recently. There are three variable conditions which are used in this study research. First, fin lengths of 4000mm, 6000mm, 8000mm and 0, 4, 8 fin types were applied rut each vaporizer. Second, we applied four season condition which consist of humidity, temperature and air velocity to the experimental environment. Finally, pressure was applied to get flow rate during experiment. This paper objective is to propose vaporizer type and length data for best performance of vaporizer through experiment.

• 한국콘텐츠학회:학술대회논문집
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• 한국콘텐츠학회 2005년도 춘계 종합학술대회 논문집
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• pp.107-111
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• 2005

본 논문에서는 MSSL에서 사용되는 전달 계층에서의 암호화 알고리즘을 개선하였는데 보다 높은 효율성을 보장하기위해 기존의 SEED 알고리즘에서 G-함수를 개선한 ISEED (Improved SEED) 알고리즘을 제안하였다. 이를 위해 라운드키 생성과정에서 가장 많은 시간이 소요되는 라운드키 값을 계산할 때 라운드 함수의 구현에서 사용된 모듈만으로 서브키를 생성할 수 있도록 알고리즘을 구현하였다. 또한 키생성 알고리즘에서 암 복호화 과정에서 필요로 하는 암호키를 서브키의 형태로 변환하는 과정에서 ISEED 알고리즘에서는 이 변환 알고리즘을 분석하고 서브키 간의 규칙성을 이용, 차분분석에 필요한 평문의 개수를 최소화함으로써 암 복호화에 소요되는 시간을 줄였다. ISEED를 기존의 알고리즘과 라운드키 생성 시간, 라운드 증가에 따른 키 생성시간과 암호화 및 복호화의 평균 수행속도를 측정하여 비교 분석하여 개선되었음을 증명하였다.

• 한국전산유체공학회지
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• 제18권4호
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• pp.74-81
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• 2013

A numerical design analysis is conducted to search for an optimal shape of outlet in a rotating-disk CVD reactor. The goal is to suppress flow recirculation that has been found in a reactor having a sudden expansion of flow passage outside of the rotating disk. In order to streamline gas flow, the sidewall at which the flow in the Ekman layer is impinged, is tilted. The axisymmetric laminar flow and heat transfer in the reactor are simulated using the incompressible ideal gas model. For the conventional vertical sidewall, the flow recirculation forming in the corner region could be expanded into the interior to distort the upstream flow. The numerical results show that this unfavorable phenomenon inducing back flow could be dramatically suppressed by tilting the sidewall at a certain range of angle. The assessment of deviation in deposition rate based on the characteristic isotherm illustrates that the sidewall tilting may expand the domain of stable plug-like flow regime toward higher pressure. A physical interpretation is attempted to explain the mechanism to suppress flow recirculation.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2002년도 International Meeting on Information Display
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• pp.773-776
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• 2002

Efficient organic white light-emitting diodes are fabricated by doping [bis(2-methyl-8-quinolinolato) (tripheny-siloxy)aluminium (III)] (SAlq), a blue-emitting layer, with a red fluorescent dye of 4-dicyanomethylene-2-methyl-6-{2-(2,3,6,7-tetrahydro-1H,5H-benzo[i,j]quinolizin-8-yl)vinyl}-4H-pyran (DCM2). The incomplete energy transfer from blue-emitting SAlq to red-emitting DCM2 enables to obtain a balanced white light-emission. A device with the structure of ITO/TPD (50 nm)/SAlq:DCM2 (30 nm, 0.5 %)/$Alq_3$ (20 nm)/LiF (0.5 nm)/AI shows emission peaks at 456 nm and 482 nm from SAlq and at 570 nm from DCM2. The white light-emitting device shows an external quantum efficiency of about 2.3 %, a luminous efficiency of about 2.4 lm/W, and the CIE chromaticity coordinates of (0.32, 0.37) at 100 cd/m^2. A maximum luminance of about 23,800 cd/m^2. is obtained at 15 V and the current density of 782 mA/cm^2.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 추계학술대회 논문집 Vol.14 No.1
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• pp.545-549
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• 2001

We have produced electrolyte solution out of 1.15M $LiPF_6$ EC/EMC/DEC/PC(30/55/10/5 by vol%) as a reference, and at the same time, performed basic physical property test using a single solvent of 1.15M $LiPF_6$ DEC, DMC, EMC and a 2 component electrolyte solution of 1.15M $LiPF_6$ EC/DEC(1/2 by vol%) and PC/DEC(1/2 by vol%). Cyclic Voltammetry Analysis showed that, compared to existing carbonate organic solvent, the addition of DEC,DMC and EMC brought the de-decomposition peak of salt anion of $PF_6$ and the solvent at lower oxidization potential of 2.3V, 0.7V and 2.1V(vs. $Li/Li^+$). In addition, a kinetics current peak, in which intercalation of Lt is proceeded at 750mV, 450mV(vs. $Li/Li^+$), was confirmed. These findings suggest that the DEC solvent decomposition occurred at an electric potential lower than that of oxidization of existing carbonate organic solvent. Through the impedance analysis, we checked electric charge transfer resistance($R_{ct}$) according to the electric potential of $Li^+$ intercalation at 750mV(vs. $Li/Li^+$), which was the same as the resistance ($R_f$) and cyclic voltammetry of SEI film that was formed at Reference. By doing so, we found that the significant decrease of polarization resistance($R_p$) when Reference was played a part in the formation of compact SEI layer at the initial decomposition reaction.

• 한국산학기술학회논문지
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• 제14권4호
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• pp.1976-1981
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• 2013

본 논문에서는 직접 대역 확산 (direct-sequence spreading spectrum) 시스템을 위한 주파수 영역 간섭 (tone interference) 신호 제어 알고리듬을 제안한다. 기존에 제안된 주파수 영역 간섭 제거 기법들에서는 프로토콜들의 모음을 의미하는 전송제어 프로토콜(TCP: Transmission Control Protocol) 트랜스포트 계층에서 가장 광범위하게 사용되어 왔다. 양방향 트래픽을 네트워크 경로를 통해 동일한 종단 노드 쌍 사이의 반대 방향에서 데이터를 전송하는 두 개 또는 그 이상의 TCP 연결로부터 생긴 트래픽 패턴을 사용하고 네트워크의 교환기와 라우터들을 공유하므로 승인의 결과를 초래한다. per-flow 입출력 반응을 사용하여 LTS 상관 구조를 온라인으로 평가할 때 이는 중요한 요인이 된다. TCP-MT는 연결 지속 기간이 길 때 가장 큰 성능 이득을 제공한다.

• 대기
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• 제19권4호
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• pp.319-329
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• 2009

The intensive dust observation experiment has been performed at Korea Global Atmosphere Watch Center (KGAW) in Anmyeon, Korea during each spring season from 2007 to 2009. Downward and upward hyper-spectral spectrums over the dust condition were measured to understand the hyper-spectral properties of Asian dust using both ground-based Fourier Transform Infrared Spectroscopy (FT-IR) and space-borne AIRS/Aqua. To understand the impact of the Asian dust, a Line-by-Line radiative transfer model runs to calculate the high resolution infrared spectrum over the wave number range of $500-500cm^{-1}$. Furthermore, the radiosonde, a $PM_{10}$ Sampler, a Micro Pulse Lidar (MPL), and an Aerodynamic Particle Sizer (APS) are used to understand the vertical profile of temperature and humidity and the properties of Asian dust like concentration, altitude of dust layer, and size distribution. In this study, we found the Asian dust distributed from surface up to 3-4 km and volume concentration is increased at the size range between 2 and $8{\mu}m$ The observed dust spectrums are larger than the calculated clear sky spectrums by 15~60K for downward and lower by around 2~6K for upward in the wave number range of $800-1200cm^{-1}$. For the characteristics of the spectrum during the Asian dust, the downward spectrum is revealed a positive slope for $800-1000cm^{-1}$ region and negative slope over $1100-1200cm^{-1}$ region. In the upward spectrum, slopes are opposed to the downward one. It is inferred that the difference between measured and calculated spectrum is mostly due to the contribution of emission and/or absorption of the dust particles by the aerosol amount, size distribution, altitude, and composition.