• 한국게임학회 논문지
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• 제7권2호
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• pp.21-32
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• 2007

물체 내부에서의 빛의 산란 현상 (subsurface scattering)에 기반한 조명 모델은 사실적인 이미지 생성에서 매우 중요하지만, 복잡한 계산으로 인하여 게임, 가상현실 등의 대화형 환경에 적용되기 어려웠다. 우리는 빛의 단일 산란과 다중 산란 현상에 의한 조명을 이미지 상에서 근사하는 보다 실용적인 기법을 제안한다. 먼저 광원 시점에서 렌더링한 이미지의 각 픽셀에 물체 내부로 투과된 조사도 정보를 저장하고, 쉐이딩 단계에서 이 정보를 사용하여 조명을 빠르게 계산한다. 단일 산란은 그림자 매핑과 유사한 알고리즘과 적응적인 결정적 샘플링을 통해 수행 비용을 효율적으로 줄인다. 다중 산란은 빛의 확산 이론에 기반한 계층적인 샘플링을 사용한다. 복잡한 함수의 테이블화은 속도를 보다 향상 시킨다. 실험을 통해 제안된 기법이 초당 수 십에서 수 백 프레임의 빠른 속도로 사실감있는 장면을 렌더링할 수 있으며, 게임과 같은 기존의 대화형 환경에 쉽게 적용될 수 있음을 보여준다.

• 대한전기학회논문지
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• 제41권8호
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• pp.858-868
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• 1992

0.085Ba(LaS11/2TNbS11/2T)OS13T-0.915Pb(ZrS1yTTiS11-yT)OS13T (0.45$\leq$y$\leq$0.65) transparent electrooptic ceramics were fabricated by two-stage sintering method. The structural, ferroelectric and electrooptic properties were investigated varying composition and second sintering time. Also the possibility of application to electrooptic device was studied. If we increase the PbZrOS13T contents, dielectric constants were increased and Curie temperature was decreased. In the composition of 0.55[mol] PbZrOS13T, electromechanical coupling factor and piezoelectric charge constant were the highest values of 43[%] and 173x10S0-12T[C/N], respectively. Mechanical quality factors were decreased with the increasing PbZrOS13T contents. Light transmittance was increased with wavelength when measured from 300[nm] to 900[nm], and with PbZrOS13T contents in the range of 0.50[mol]-0.65[mol], and had the highest value of 67[%] in the composition of 0.65[mol] PbZrOS13T. From the results of ferroelectric hysteresis loop and transmitted light intensity with electric field, the specimens with compositions of 0.65,0.60,0.55[mol] PbZrOS13T were applicable to electrooptic memory device and those with compositions of 0.50,0.45[mol] PbZrOS13T were applicable to linear electrooptic device.

• 한국포장학회지
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• 제27권3호
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• pp.203-210
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• 2021

With the development of package printing technology, the package has expanded from the basic function of protecting products to the marketing function through package design. Color, the visual element that composes the package design, is delivered to the consumer most quickly and effectively. As color marketing of these package designs expands, accurate color reproduction that the product wants to express is becoming more important. The color of an object is transmitted by absorption and scattering of light. Spectral reflectance refers to the intensity of light reflected by an object at different wavelengths by the spectral effect. As a result, the color of the object is expressed in various colors. Packaged printing inks have their own absorption and scattering coefficients, and the Kubelka-Munk model for color reproduction and prediction defines the relationship between these correlation coefficients through reflectance. In the Kubelka-Munk model for color reproduction and prediction, the relationship between the absorption and scattering coefficients (K/S) of printed material is predicted as the sum of the K/S values according to the mixing ratio of all color ink used. In this study, the reflectance of the measured print is reversely calculated at the mixing ratio of print ink using the Kubelka-Munk model. Through this, the relationship value of the ink-specific absorption/scattering coefficient constituting the final printed material is predicted. Delta E is derived through the predicted reflectance, and the similarity between the measured value and the predicted value is confirmed.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제44회 동계 정기학술대회 초록집
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• pp.176-177
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• 2013

Surface plasmon polaritons (SPPs) have attracted the attention of scientists and engineers involved in a wide area of research, microscopy, diagnostics and sensing. SPPs are waves that propagate along the surface of a conductor, usually metals. These are essentially light waves that are trapped on the surface because of their interaction with the free electrons of conductor. In this interaction, the free electrons respond collectively by oscillating in resonance with the light wave. The resonant interaction between the surface charge oscillation and the electromagnetic field of the light constitutes the SPPs and gives rise to its unique properties. In this papers, we studied theoretical and experimental extraordinary transmittance (T) and reflectance (R) of 2 dimensional metal hole array (2D-MHA) on GaAs in consideration of the diffraction orders. The 2d-MHAs was fabricated using ultra-violet photolithography, electron-beam evaporation and standard lift-off process with pitches ranging from 1.8 to $3.2{\mu}m$ and diameter of half of pitch, and was deposited 5-nm thick layer of titanium (Ti) as an adhesion layer and 50-nm thick layer of gold (Au) on the semiinsulating GaAs substrate. We employed both the commercial software (CST Microwave Studio: Computer Simulation Technology GmbH, Darmstadt, Germany) based on a finite integration technique (FIT) and a rigorous coupled wave analysis (RCWA) to calculate transmittance and reflectance. The transmittance was measured at a normal incident, and the reflectance was measured at variable incident angle of range between $30^{\circ}{\sim}80^{\circ}$ with a Nicolet Fourier transmission infrared (FTIR) spectrometer with a KBr beam splitter and a MCT detector. For MHAs of pitch (P), the peaks ${\lambda}$ max in the normal incidence transmittance spectra can be indentified approximately from SP dispersion relation, that is frequency-dependent SP wave vector (ksp). Shown in Fig. 1 is the transmission of P=2.2 um sample at normal incidence. We attribute the observation to be a result of FTIR system may be able to collect the transmitted light with higher diffraction order than 0th order. This is confirmed by calculations: for the MHAs, diffraction efficiency in (0, 0) diffracted orders is lower than in the (${\pm}x$, ${\pm}y$) diffracted orders. To further investigate the result, we calculated the angular dependent transmission of P=2.2 um sample (Fig. 2). The incident angle varies from 30o to 70o with a 10o increment. We also found the splitting character on reflectance measurement. The splitting effect is considered a results of SPPs assisted diffraction process by oblique incidence.

• 융합정보논문지
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• 제12권2호
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• pp.30-36
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• 2022

본 논문에서는 가시광 통신시스템의 조명과 통신의 기능을 동시에 사용할 때, 조명의 Dimming Level 향상과 Flicker 현상을 줄일 수 있는 기법에 대해서 제안한다. 가시광 통신은 통신과 조명의 성능을 함께 만족해야 한다. 그러나 기존의 Data Code Mapping 방식은 전체 조명의 밝기를 감소시키는 결과를 나타낸다. 이는 조명의 성능 저하와 Flicker 현상을 유발한다. 이를 해결하기 위해, 본 논문에서는 전송 알파벳에 대해서 binary code 할당하고, 문자열에 알파벳의 발생 빈도율에 따라 할당된 binary code를 최적화하여 매칭 시키는 적응 학습형 코드 할당 기법을 제안하였다. 이를 통해, 각각의 문자열의 최대 Dimming level을 유지하면서 동시에 'OFF' 패턴이 연속적으로 발생하지 않도록 코드를 할당하여 통신 기능뿐만 아니라 조명으로써의 역할을 충실히 할 수 있는 기법에 대해서 연구하였다. 성능평가 결과, 전체 통신 성능에 큰 영향을 주지 않으면서, '1'의 발생 빈도가 유의미하게 증가하였고 반대로 연속적인 '0' 빈도율이 감소하여 시스템의 조명 성능이 크게 향상된 것을 보였다.

• ETRI Journal
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• 제7권4호
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• pp.3-10
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• 1985

비간섭성 LED 광원으로 부터의 빛이 다중모우드 광섬유를 약 10km이상 지났을 때 광의 입사조건에 무관하게 정상상태(Steady-state) 에 이르며, 정상상태의 광섬유 출사단의 near-field 광 파워 분포가 가우시안(Gaussian) 함수 형태임을 알 수 있었다. 이 가우시안 함수형태의 정상상태에서 측정된 광섬유의 손실은 매우 안정된 측정치를 나타내었다. 한편 가간섭성 LD광원을 사용할 경우 10km까지 near-field광 파워 분포에서 스페클(Speckle) 현상을 볼 수 있었고, LD의 간섭성과 발광 모우드 형태의 불균일로 인하여 20km 이상까지 LED에서와 같은 정상상태에 이르지 않고 있었으나 이 상태에서 측정된 광섬유의 손실치는 비교적 안정하였다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2003년도 ICCAS
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• pp.41-44
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• 2003

We propose portable equipment that monitors current and voltage of high-potential power transmission lines. In the equipment, a current and voltage sensor are attached to an insulator that supports a power transmission line: A clamped to the power line and the detected current signal is transmitted to the ground station by a wireless optical link using transmission line is detected by a high resistance element, zinc oxide (ZnO). That acts as a potential divider between the power line and ground. We make an experimental device for 66kV power line and demonstrate that it can monitor currents proposed equipment is small-sized, light, and inexpensive in comparison with the conventional CT (current transformer) and PT (potential transformer) since it does not require high potential insulators and magnetic cores, further, the equipment is easily installed owing to its small size and its simple structure.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2002년도 ITC-CSCC -1
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• pp.568-570
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• 2002

With the development of Wavelength Division Multiplexing (WDM) and Optical Cross-Connect (OXC) systems, an efficient integration of IP and WDM has been focused. The Optical Internetworking Forum (OIF) proposes a new model that is called Overlay model for the integration of IP and WDM. In the Overlay model, UNI 1.0 signaling is adopted to establish signaling interface between Optical and IP network. UNI 1.0 signaling consists of a lot of functions; especially, reliability, light traffic, and etc. For that reason, Srefresh and ACK messages in UNI signaling support reliable messaging and reduce the amount of information that must be transmitted and processed in order to maintain RSVP states and processing time. This paper focuses on an implementation of Srefresh and ACK messages based on UNI 1.0 signaling and comparison between before and after implementing. The results show that Srefresh and ACK messages improve intelligence in the control plane of the optical network, which will make them more survivable, flexible, reliable, and controllable.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1991년도 추계학술대회 논문집 학회본부
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• pp.325-328
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• 1991

In this study, $0.085Ba(La_{1/2}Nb_{1/2})O_3-0.915Pb(Zr_yTi_{1-y})O_3$(y=0.45, 0.50, 0.55, 0.60, 0.65[mol]) transparent electrooptic ceramics were fabricated by two-stage sintering method. Increasing the $PbZrO_3$ contents, dielectric constant was increased and Curie temperature was decreased. In the composition of 0.55[mol] $PbZrO_3$, electromechanical coupling factor was 0.43. From the results of ferroelectric hysteresis loop and transmitted light intensity with electric field, the compositions of 0.65, 0.60, 0.55[mol] $PbZrO_3$ was applicable to electroopticmemory device and the compositions of 0.50, 0.45[mol] $PbZrO_3$ was applicable to linear electrooptic device.

• Journal of Welding and Joining
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• 제25권2호
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• pp.43-48
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• 2007

Laser Transmission Joining (LTJ) of plastics is a process in which light of suitable wavelength is transmitted through a transparent substrate that is in contact with an absorbing one. In this paper, LTJ is investigated by preliminary experiments from the viewpoint of mechanical engineering. To understand transmitting characteristics of each polymer substrate, transmission rate, reflection rate and absorption coefficient of polymer are measured by using a laser power-meter. Characteristics of joining in the spot welding and seam welding are investigated by measuring the fracture load. Fracture load increases in accordance to the laser power and irradiation time. However, when the laser power is over 60W and irradiation time over 4seconds, fracture load decreases. This phenomenon is probably due to heat-softening of materials. Besides, cavities are generated at a joint by evaporation of water molecules, which can be suppressed by introduction of a gap between two substrates.