• 한국음향학회지
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• 제25권8호
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• pp.389-394
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• 2006

중주파수 양상태 잔향음 준위는 음선이론을 사용하여 산출되었다. 제안된 알고리즘은 음파전달 경로 내 전방/후방 산란의 상호작용을 가정한다. 해양환경 (지형. 해저면 산란, 해수면 산란 등)은 거리 독립 해양환경으로 가정되었고 중주 파수 산란 모델이 사용되었다. 해상실험 자료를 사용한 알고리즘 검증 결과 양상태 잔향음 모델 알고리즘이 관측 해역의 양상태 잔향음 특성을 잘 반영하고 있음을 확인하였다.

• 대한기계학회논문집
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• 제16권2호
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• pp.267-280
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• 1992

This paper describes a numerical analysis of the light scattering patterns of roughness profiles. This analysis was based upon the light scattering theory developed by Beckmann. In the analysis, the roughness profile was regarded as a profile whose irregularities depend on the production process and the shape of cutting tool. Generally, waviness of an actual surface seriously distorts the scattered pattern of roughness profile. In order to avoid the effects of waviness of actual surfaces, several theoretically calculated scattering patterns, instead of actual scattering patterns, were used to analyze the scattering patterns of typical engineering roughness profiles. The characteristics of the light scattering patterns for five model surfaces were studied.

• 한국음향학회지
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• 제22권3호
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• pp.162-168
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• 2003

콘서트홀의 음향성능을 결정짓는 중요한 요소 중의 하나로 알려진 확산현상은 실내마감재료의 "확산계수"에 의해 결정된다. 확산음장에서 임의입사 확산계수를 측정하도록 제안한 ISO (International Organization for Standardization)측정방법을 기반으로 목재 반구 확산체와 각재확산체의 크기 및 점유밀도 변화에 따른 확산계수를 축소잔향실에서 측정하였다. 측정결과 15㎝이상 높이의 반구가 가장 높은 확산계수를 보였으며, 반구의 경우 전체 점유밀도가 50%에서, 각재의 경우는 약 30% 점유에 각각 높은 확산계수를 보였다.

• 반도체디스플레이기술학회지
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• 제13권2호
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• pp.37-44
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• 2014

In this study, the performance of dye-sensitized solar cells with different thickness of the photelectrode film was simulated by using the electron-diffusion differential model. Through this simulation, the relationships between the thickness of the photoelectrode film and the performances (open-circuit voltage, short-circuit current density, and overall photoelectric-conversion efficiency) of cells were understood and the performances with different thickness of the photoelectrede film were also examined. For considering the refractive index in the liquid electrolyte and exploring the scattering effect of titanium dioxide particles with different sizes using the Mie light-scattering theory, the highest scattering effect of each particles was found out and the optimal size of the titanium dioxide particle was determined for light scattering in the photoelectrode film of dye-sensitized solar cell. Through experiment, the mixed titanium dioxide cell was better than the single titanium dioxide cell and generated a higher overall conversion efficiency because the optimal titanium dioxide particles in the phoelectrode film as light scattering.

• 전자공학회논문지D
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• 제35D권8호
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• pp.31-37
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• 1998

A new self-consistent hole mobility model that includes lattice and hole temeprature has been proposed. By including the lattice and hole temperatures as well as the effective transverse field and the interface fixed charge, the model predicted the saturation of hole drift velocity and showed the effects of coulomb scattering, surface phonon scattering, and surface roughness scattering. The calculated data by the model were compared with the reported experimental data and they were shown to agree quite well. The new model is expected to estimate the characteristics of very short channel devices in the in the hydrodynamic model simulation.

• 대한기계학회논문집A
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• 제26권11호
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• pp.2457-2465
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• 2002

Numerical modeling of a nondestructive testing system plays an important role in many aspects of quantitative nondestructive evaluation (QNDE). The ultimate goal of a model is to predict test results for a specific flaw in a material. Thus, in ultrasonic testing, a system model should include the transducer, its radiation pattern, the beam reflection and propagation, and scattering from defects. In this paper attention is focused on the scattering model and the scattered fields by defects are observed by an elastodynamic boundary element method. Flaw types addressed are void-like and crack-like flaws. When transverse ultrasonic waves are obliquely incident on the flaw, the angular distribution of far-field scattered displacements are calculated and presented in the form of A-scan mode. The component signals obtained from each scattering problem are identified and their differences are addressed. The numerical results are also compared with those obtained by high frequency approximate solutions.

• 한국수산과학회지
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• 제43권4호
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• pp.380-385
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• 2010

Several theoretical acoustic scattering models were applied to estimate the target strength (TS) for assessing the biomass of zooplankton, to overcome the difficulty of direct measurements. Acoustical scattering characteristics of copepods were estimated using three theoretical models, and the application of the models was evaluated for four frequencies of a scientific echo sounder. The scattering directivity by the body shapes of copepods at 200 kHz and 420 kHz was significantly affected by TS patterns. Averaged TS, however, were similar at higher frequencies. Consequently, a low frequency model, such as a truncated fluid sphere model, provides a good acoustical biomass estimation. The regressions of TS and 30 logL were < $TS_{200\;kHz}$ >= 30logL-118.4 ($R^2=0.716$) and < $TS_{420 kHz}$ > =30 logL-108.8 ($R^2=0.758$), respectively.

• 대한조선학회논문집
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• 제42권4호
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• pp.421-426
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• 2005

Scattering center extraction schemes for radar cross section reduction of large complex targets, like warships, was developed, which are an 1-D radar image method(range profile), and a direct analysis based on an object precision method. The analysis result of partial dihedral model shows that the presented direct analysis method is more efficient than the 1-D radar image method for scattering center extraction of interested targets, in terms of radar cross section reduction design, not signal processing. In order to verify the accuracy of the direct analysis method, a scattering center analysis of an naval weapon system was carried out, and the result was coincident with that of another well-known RCS analysis program. Finally, an analysis result of RCS and its scattering center of an 120m class warship-like model presented that the direct analysis method can be an efficient and powerful tools for radar cross section reduction of large complex targets.

• 한국멀티미디어학회논문지
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• 제8권1호
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• pp.88-100
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• 2005

인간의 피부를 사실적으로 렌더링하는 것은 그 동안 컴퓨터 그래픽스 분야에서 난제로 여겨져 왔으며 지금까지도 중요한 연구 과제로서 남아있다. 피부와 같은 반투명성 물질은 표면하 산란을 포함한 복잡한 광학 특성을 가진다. 본 논문에서는 사실적인 피부 렌더링을 위해 표면하 산란을 고려한 쉐이더를 제안하고 3D 패키지, 마야의 플러그인 형태로 구현하였다. 구현된 피부 쉐이더를 적용한 렌더링 이미지는 기존의 전통적인 쉐이딩 기법을 이용한 이미지에 비해 보다 더 사실적인 피부의 표현이 가능하였고 피부의 피지, 표피, 진피 층을 각각 정반사, 다중 산란, 단일 산란으로 모델링할 수 있었다.

• Ocean and Polar Research
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• 제26권2호
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• pp.133-143
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• 2004

For the purpose of understanding the cloud scattering effect of UV radiation at King Sejong station In West Antarctica, we analyzed the data measured by UV-Biometer at surface and compared its result with solar radiation model. The parameterization of UV radiation by cloud ice crystal was applied to solar radiation model and the sensitivity of this model for the variation of ice crystal was tested. The cloud optical thickness was calculated by using this solar radiation model. It was compared the result from calculation with CERES satellite data. In solar radiation model, the UV radiation was less scattered with increase of ice crystal size in cloud and this scattering effect was more important to UV-A radiation than Erythemal UV-B radiation. But scattering effects by altitude of cloud was not serious. The calculated cloud optical thicknesses in Erythemal UV-B and UV-A region were compared with CERES satellite data and the result by UV-A was more accurate than Erythemal UV-B region.