• 한국항행학회논문지
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• 제13권1호
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• pp.27-33
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• 2009

채널 전송률이 40 Gbps인 WDM 채널들의 성능을 개선시키는 새로운 광전송 링크 기술을 제안하였다. 제안된 광전송 링크는 전체 전송로 중간에 광 위상 공액기 (optical phase conjugator)를 두고 전송로에서 축적된 분산은 분산 제어 (DM; dispersion management)을 통해 보상하는 구조이다. DM이 OPC와 결합하면 DM을 통해 전송 링크 전체에서 축적된 분산량을 줄여줌과 동시에 OPC에 의한 비선형성 보상의 정도를 더욱 좋게 하여 결과적으로 모든 채널들의 Q-factor가 크게 개선되는 것을 확인하였다. 그리고 모든 WDM 채널들의 Q-factor 개선은 광전송 링크의 전체 잉여 분산 (NRD; net residual dispersion)에 크게 의존한다는 것을 알 수 있었다.

• 한국실내디자인학회논문집
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• 제17호
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• pp.60-64
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• 1998

The results of simulation on greenery ratio using CG are as follows: arrangement type of optimal condition and greenery ratio were summarized as below as dispersion type and 5% ratio greenery for 20 pairs of assessment items and these assessment items were classified into 5 factors as a result of factor analysis,. These factors were Harmony Animation Atmosphere texture Peculiarity. Verification results of factors differences according to each condition can be. there was no apparent difference among factors in accordance with gender, In case of arrangement type dispersion type was higher than concentration type in all factors. Based on the above results dispersion type was assessed higher than concentration type the most suitable condition of Harmony Factor was 5% dispersion type Animation Factor was 5% dispersion type Animation Factor was 7% dispersion type Atmosphere Factor was 10% dispersion type Texture Factor was 5% concentration type and $\ulcorner$Peculiarity Factor$\lrcorner$was 7% concentration type.

• Journal of electromagnetic engineering and science
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• 제8권4호
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• pp.139-143
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• 2008

In this paper, a new scheme to calculate the weighting factor of the 2-D isotropic-dispersion finite difference time domain(ID-FDTD) is proposed. The weighting factor in [1] was formulated in free space, so that it may not be optimal in dielectric media. Therefore, the weighting factor was reformulated by considering the material properties and using the least mean square method. As a result, a minimum numerical dispersion error for any dielectric media is guaranteed.

• 방사성폐기물학회지
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• 제19권2호
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• pp.177-186
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• 2021

Radioactive materials from nuclear power facilities can be released into the atmosphere through various channels. Recently, the dispersion of radioactive materials has become critical issue in Korea after Kori Unit 1 and Wolsong Unit 1 were permanently shut down. In this study, annual atmospheric dispersion factors were compared based on the continuous release and purge release using the XOQDOQ computer program, a method for calculating atmospheric dispersion factors at commercial nuclear power stations. The meteorological data analyzed in this study was based on the Shin Kori nuclear power meteorological tower which has the largest operating nuclear power plants in Korea, for three years (from 2008 to 2010). The analysis results of the dispersion factor of the radioactive material release obtained using the XOQDOQ program showed that the difference between the continuous release and purge release was within two times. This study will be valuable helpful for revealing the uncertainty of the predictive atmospheric dispersion factor to achieve regulation.

• 한국음향학회지
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• 제18권4호
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• pp.47-52
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• 1999

본 논문에서는 특징 파라미터의 분산과 인식성능에 대한 기여도를 고려하여 각 특징 파라미터를 가중시키는 방법을 제안하였다. 각 특징 파라미터의 인식률에 비례하게 전체 기여도를 설정하고, 각 특징 파라미터의 분산에 따라 가중요인을 설정하였다. 전체 기여도와 분산에 따른 가중요인을 사용하여 각 특징 파라미터의 상태별 가중치를 설정하였다. 제안한 방법의 유효성을 살펴보기 위해 유사음소 단위의 HMM 음성인식시스템을 사용하여 인식실험을 하였다. 인식실험에서 제안한 방법으로 가중치를 설정하였을 경우에 인식률이 7.7% 향상됨을 볼 수 있었다.

• 대한공간정보학회지
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• 제14권1호
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• pp.57-63
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• 2006

본 연구에서는 신호연동화에 관한 기초적인 이론에 대하여 고찰하고 광주시 죽봉로의 광천4거리에서 농성광장에 이르는 3개 교차로를 사례지구로 하여 포화교통류율 및 차량군 분산계수 산정기법들을 적용하여 분산계수에 따른 민감도를 분석하는 과정으로 연구를 진행한 결과 다음과 같은 성과를 얻을 수 있었다. 1. 차량군 분산계수는 0.28-0.33으로 같은 지점의 교차로에서도 관측위치에 따라 상류부보다는 하류부가 더 작은 값을 나타내었다. 2. 차량군지수는 큰 변화를 보였으나 수행지수는 미세한 편차를 보였다. 이는 차량분산계수를 0.34로 설정하여 평가하여도 무리가 없음을 나타내었다. 3. T7F 모형에서 연동화 설계 시 차량분산계수 변화에 따른 수행지수값의 민감도가 미소한 것으로 나타났다.

• 한국대기환경학회지
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• 제13권5호
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• pp.383-396
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• 1997

Numerical prediction of the pollutant dispersion over a two-dimensional hilly terrain is presented. The dispersion model used in the present work is based on the gradient diffusion theory and the finite-volume method on a non-orthogonal boundary-fitted grid system. The numerical model is validated by comparing the results with the available experimental data for the flat-floor dispersion within a turbulent boundary-layer. The numerical error analysis is performed based on the guideline of Kasibhatla et al.(1988) for the elevated-source dispersion in the flat-floor boundary layer having a power-law velocity and linear eddy-diffusivity profile. The influences of the two-dimensional hilly terrain on the dispersion from a continuously released source are numerically investigated by changing the emission locations and heights. It is found that the distributions of ground-level concentration are strongly influenced by the source location and the emission height. Hence, the terrain amplification factor is greatly enhanced when the pollutant source is located within a flow separation region. Dispersion from a source of short duration is also simulated and the duration time of the pollutant is compared at several downstream locations on a hilly terrain. The results of the numerical prediction are applied to the evaluation of environmental impacts due to the automobile exhausts at the seashore highway with a parallel mountain range.

• Journal of electromagnetic engineering and science
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• 제13권3호
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• pp.158-164
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• 2013

This paper expands a previously proposed optimized higher order (2, 4) finite-difference time-domain scheme (H(2, 4) scheme) for use with lossy material. A low dispersion error is obtained by introducing a weighting factor and two scaling factors. The weighting factor creates isotropic dispersion, and the two scaling factors dramatically reduce the numerical dispersion error at an operating frequency. In addition, the results confirm that the proposed scheme performs better than the H(2, 4) scheme for wideband analysis. Lastly, the validity of the proposed scheme is verified by calculating a scattering problem of a lossy circular dielectric cylinder.

• Journal of Radiation Protection and Research
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• 제41권3호
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• pp.260-267
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• 2016

Background: This study analyzes the differences in the annual averaged atmospheric dispersion factor and ground deposition factor produced using two classification methods of atmospheric stability, which are based on a vertical temperature difference and the standard deviation of horizontal wind direction fluctuation. Materials and Methods: Daedeok and Wolsong nuclear sites were chosen for an assessment, and the meteorological data at 10 m were applied to the evaluation of atmospheric stability. The XOQDOQ software program was used to calculate atmospheric dispersion factors and ground deposition factors. The calculated distances were chosen at 400 m, 800 m, 1,200 m, 1,600 m, 2,400 m, and 3,200 m away from the radioactive material release points. Results and Discussion: All of the atmospheric dispersion factors generated using the atmospheric stability based on the vertical temperature difference were shown to be higher than those from the standard deviation of horizontal wind direction fluctuation. On the other hand, the ground deposition factors were shown to be same regardless of the classification method, as they were based on the graph obtained from empirical data presented in the Nuclear Regulatory Commission's Regulatory Guide 1.111, which is unrelated to the atmospheric stability for the ground level release. Conclusion: These results are based on the meteorological data collected over the course of one year at the specified sites; however, the classification method of atmospheric stability using the vertical temperature difference is expected to be more conservative.

• 한국전자파학회논문지
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• 제21권7호
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• pp.805-814
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• 2010

기존 Crank-Nicolson FDTD 기법(CN FDTD 기법)의 비등방성 분산 특성을 개선하기 위한 CN ID-FDTD 기법을 제안하였다. 제안한 CN ID-FDTD 기법은 공간 미분 연산을 위해 기존 CN FDTD 기법의 centered 유한 차분식 (Finite Difference equation: FD 연산식)이 아닌 isotropic-dispersion 유한 차분식(ID-FD 연산식)$^{[1],[2]}$을 이용한다. 본 논문에서는 손실 매질에 대한 CN ID-FDTD 기법의 분산 관계식을 유도하였고, 이 분산 관계식을 이용해 ID-FD 연산식에서 분산 오차(dispersion error)를 줄이는 가중치(weighting factor)와 보정값(scaling factor)을 제시하였다. 그리고 해석 결과의 정확성 비교를 통해 CN ID-FDTD 기법에서는 기존 CN FDTD 기법의 단점이었던 비등방성 분산 오차가 확연하게 감소하는 것을 확인하였다.