• 한국전자파학회논문지
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• 제22권4호
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• pp.407-415
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• 2011

본 논문에서는 등방성(isotropic) 특성과 작은 분산 오차(low dispersion error)를 갖는 3차원 등방성 시간 영역 유한 차분법(ID-FDTD: Isotropic Dispersion Finite Difference Time Domain) 방법의 stability condition과 광대역 해석 특성에 대해 논의하였다. 3차원 ID-FDTD 방법은 기존의 Yee FDTD 방법의 비등방성 특성과 큰 분산 오차를 개선하기 위해 제안되었다. 기존 연구에서는 3차원 ID-FDTD 방법의 stability condition을 수치적으로 계산하였지만, 이에 대한 검증이 충분히 이뤄지지 않은 상태이다. 이에 본 논문에서는 단일 주파수와 광대역 주파수 신호를 입력원으로 한 모의 실험 환경에서 3차원 ID-FDTD 방법의 stability condition 검증을 수행하였다. 또한 광대역 특성에 대해 3차원 ID-FDTD 방법과 유사한 알고리즘들을 비교 분석해 해보았고, 마지막으로 3D ID-FDTD을 적용하여 대형 크기 구 모델에 대해 radar cross section(RCS) 해석을 수행함으로써, 실질적 해석을 통한 알고리즘 검증 및 분석을 마무리 하였다.

• 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.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2011년도 추계학술대회
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• pp.650-652
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• 2011

축적된 분산(dispersion)과 비선형 효과에 의한 광 신호의 왜곡을 보상하기 위해 중계 구간의 잉여 분산 (RDPS; residual dispersion per span)이 랜덤하게 분포하는 분산 제어 (DM; dispersion management)가 적용되고 전체 전송로 중간에 광 위상 공액기 (OPC; optical phase conjugator)를 둔 광전송 링크를 통해 40 Gbps 광 신호를 최상의 성능으로 전송하기 위한 RDPS 랜덤 분포 조건을 도출하였다.

• 한국지하수토양환경학회지:지하수토양환경
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• 제20권2호
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• pp.10-21
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• 2015

The present study introduces a novel numerical approach for solving dispersion dominated problems with Cauchy boundary condition in an Eulerian-Lagrangian scheme. The study reveals the incapability of traditional Neuman approach to address the dispersion dominated problems with Cauchy boundary condition, even though it can produce reliable solution in the advection dominated regime. Also, the proposed numerical approach is applied to a real field problem of radioactive contaminant migration from radioactive waste repository which is a major current waste management issue. The performance of the proposed numerical approach is evaluated by comparing the results with numerical solutions of traditional FDM (Finite Difference Method), Neuman approach, and the analytical solution. The results show that the proposed numerical approach yields better and reliable solution for dispersion dominated regime, specifically for Peclet Numbers of less than 0.1. The proposed numerical approach is validated by applying to a real field problem of radioactive contaminant migration from radioactive waste repository of varying Peclet Number from 0.003 to 34.5. The numerical results of Neuman approach overestimates the concentration value with an order of 100 than the proposed approach during the assessment of radioactive contaminant transport from nuclear waste repository. The overestimation of concentration value could be due to the assumption that dispersion is negligible. Also our application problem confirms the existence of real field situation with advection dominated condition and dispersion dominated condition simultaneously as well as the significance or advantage of the proposed approach in the real field problem.

• 한국해안해양공학회지
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• 제12권4호
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• pp.190-194
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• 2000

선형파 이론에서 제시되는 유속분포를 이용하여 파랑인자에 의하여 영향을 받는 분산계수를 이론적으로 유도하였다. 유도된 분산계수는 수심평균, 주기 평균된 값으로 천해조건보다 심해조건에서 큰 값을 보이고 있다. 또한, 분산계수 값은 연직 방향 혼합시간에 비하여 큰 주기 값에서는 특정한 값으로 수렴하고, 매우 작은 주기 값에서는 0으로 되는 일반적인 경향도 보이고 있다. 한편, 단순한 지형 및 가정 하에서 유도된 본 분산계수를 보다 실질적인 상황에서도 적용할 수 있고, 천해영역의 조건을 반영할 수 있도록 보완·수정할 필요가 있다.

• Composites Research
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• 제26권6호
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• pp.337-342
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• 2013

나노입자를 이용하여 강화 효과를 높이기 위해서는 고분자 기지 내부의 균일한 분산 상태를 확보하여야 한다. 또한 균일분산 조건 확보 후 균일 분산상태를 증명할 평가자료가 필요하다. 본 연구는 에폭시 수지와 SiC 나노입자를 혼합한 SiC/에폭시 복합 수지를 제조할 경우 커패시턴스 측정법을 이용한 강화재 분산도 예측 연구를 진행하였다. 커패시턴스는 전기용량을 의미하며 측정 재료의 내부 전하량과 비례한다. 기존 에폭시 수지에 비해 나노 SiC 입자를 함유할 경우 전하량이 증가되는 이론을 바탕으로 구간별 커패시턴스 측정에 따른 분산도 평가를 진행하고, 커패시턴스 분산도 예측방법에 대한 타당성을 FE-SEM과 물리적 강도 증가 방법으로 평가하였다. 소니케이션 분산 방법과 교반기 분산 방법을 이용하여 분산 방법에 따른 SiC 나노입자 분산도 상태를 비교하였다. 인장강도와 커패시턴스 간의 상관관계가 있었으며, 파단면에 대한 비교를 할 때 분산성 향상에 대한 차이를 확인할 수 있었다.

• 대한화장품학회지
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• 제24권3호
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• pp.73-80
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• 1998

This Study was performed to get the suitable oil dispersion agent by assessment of color strength of organic pigment in non-aqueous systems. Organic pigment is used as a color expression material with other body pigments in the make-up products. But occasionally aggregation or agglomeration occurs for the lack of affinity with medium, This function is the cause of disturbing homogeneous dispersion, and then bring about an instability of products. Our study, research of dispersion mechanism between the pigment and oil phase, has been executed to solve this problem, and find a oil dispersion agent having optimum dispersion condition. Generally dispersion is related to between the solid-liquid mutual properties and electrical phenomena associated with solid-liquid interface. This factor is determined to input energy, milling time, optical properties, particle size, rheological properties, etc. Ideal dispersion state is told that coloring primary solid particle is homogeneously dispersed in medium. Good dispersed colorants are strongly and clearly appeared. We are already known that the particle size of organic pigment, chemical properties and viscosity of medium, refractive index. Consequently We determine the affinity of medium and organic pigment by measuring of color strength in the same mechanical condition. UV-VISIBLE RECORDING SPECTRO PHOTOMETER is used for measuring apparatus. We can decided the dispersion level of oil dispersion agent by measuring absorbance of color strength in the visible range that diluted medium for colloid colorant particles.

• 대한기계학회논문집B
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• 제28권1호
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• pp.89-98
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• 2004

In this paper, we develope a dispersion model based on the Generalized Langevin Model. Thomson's well-mixed condition is the well known criterion to determine particle dispersion. But, it has 'non-uniqueness problem'. To resolve this, we adopt a turbulent model which is a new approach in this field of study. Our model was greatly simplified under the self-similarity condition, leaving model only two model constants $C_{0}$ and ${\gamma}$$_{5}$ that control the dispersion and spin which measures rotational property of the Lagrangian particle trajectory. We investigated the sign of spin as well as magnitude by using the Direct Numerical Simulation. Model calculations were performed on the neutrally stable boundary layer flow. We found that spin has weak effect on the particle dispersion but it shows the significant effect on the horizontal flux compared to the zero-spin model.

• 한국축산시설환경학회지
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• 제21권1호
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• pp.1-8
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• 2015

This study was conducted to investigate the dispersion prediction of odor from Hanwoo and dairy farms. Gaussian Plume model used in considering of farm size, wind velocity, atmospheric stability and threshold odor unit to prediction of odor dispersion based on the survey on current state of odor emission and control from 9 site of Hanwoo and 9 site of dairy farms. Farm size, wind velocity and atmospheric stability were affected the distance of odor dispersion, showed longer distance in cases of large farm, low wind velocity and stable atmospheric condition. We will suggestion the adjusted distance of odor dispersion according to farm size was estimated to 50~100 m in Hanwoo farm and 50~150 m in dairy farm when apply the 3OU, 5 m/s wind velocity and stable atmospheric condition.

• 한국축산시설환경학회지
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• 제20권2호
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• pp.41-48
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• 2014

This study was conducted to investigate the dispersion prediction of odor from swine farms in Korea. Gaussian Plume model used in considering of farm size, wind velocity, atmospheric stability and threshold odor unit to prediction of odor dispersion based on the survey on current state of odor emission and control from 48 site of swine farms. Farm size, wind velocity and atmospheric stability were affected the distance of odor dispersion, showed longer distance in cases of large farm, low wind velocity and stable atmospheric condition. We will suggestion the adjusted distance of odor dispersion according to farm size was estimated to 180 m in small farm and 320 m in large farm when apply the 3 OU, 5 m/s wind velocity and stable atmospheric condition.