• Journal of Korean Society for Atmospheric Environment
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• 제22권E1호
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• pp.27-34
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• 2006

Although the importance of size-resolved raindrops study has been known, it has not been popularized up to the present. In the present study, an attempt was made to generalize the size-resolved raindrops study by a combination of the frozen raindrop collection method and a commercially available high-performance capillary electrophoresis (HPCE). Samplings were carried out at Kyoto, Japan in October 2002. The inorganic ions (chloride, nitrate, sulphate, calcium, ammonium, sodium, magnesium, potassium) in size classified raindrop samples were successfully analyzed by HPCE with good repeatability. To assure the accuracy and precision of HPCE data, t-test was conducted with paired analytical data, which were experimentally constructed by analyzing standard solutions with HPCE and IC, respectively. T-test showed that there is no notable difference between the concentrations determined by the two analytical methods. Every ionic concentration in both cation and anion was found to be strong raindrop size dependence. Though there was slight increase of sodium and sulphate concentrations between 0.85 mm and 1.15 mm raindrop radius, it showed a strong decrease for every ionic component with increasing droplet radius. The combination of the frozen raindrop collection method and a commercially available HPCE can meet the need of size-resolved raindrops study.

• 디지털융복합연구
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• 제12권1호
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• pp.519-524
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• 2014

본 연구는 빗방울 렌더링에 관한 연구이다. 기존 게임에서 빗방울을 렌더링하는 경우에는 스프라이트 이미지를 이용하거나 대략적으로 빗방울이 맺힌 텍스처를 이용한다. 이 방법은 모든 빗방울이 비슷한 모양과 크기로 렌더링되기 때문에 플레이어들에게 실제감을 제공하기에는 한계가 있다. 이 한계를 개선하기 위해 본 논문에서는 빗방울이 물체와 접촉했을 때 표면 장력을 고려한 빗방울 생성 방법을 제안하고 이를 Unity3D 엔진을 이용하여 구현한다. 본 논문의 유용성을 보여주기 위해, 표면 장력 수식의 요소인 면적과 당기는 힘의 변화에 따른 빗방울 생성을 보여준다. 본 논문은 빗방울을 게임에서 렌더링 하는 경우 실제감 있는 게임 제작에 도움을 줄 수 있다.

• 한국지구과학회지
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• 제22권2호
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• pp.105-111
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• 2001

충남 보령시 명암 지역에 분포하는 트라이아스기 후기의 아미산층으로부터 7개의 빗방울자국 표본이 발견되었다. 빗방울자국은 습윤한 아열대의 호성환경하에서 일시적 또는 계절적으로 건조한 기후에 수면의 저하시기에 형성된것으로 해석된다. 이들 빗방울자국은 하부 중생대 남포층군에서는 처음으로 발견된 것이다.

• Asian Journal of Atmospheric Environment
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• 제11권3호
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• pp.176-183
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• 2017

Although it is well known that rain plays an important role in capturing air pollutants, its quantitative evaluation has not been done enough. In this study, the effect of raindrop size on pollutant scavenging was investigated by clarifying the chemical nature of individual size-resolved raindrops and their residual particles. Raindrops as a function of their size were collected using the raindrop collector devised by our oneself in previous study (Ma et al., 2000) during high atmospheric loading for $PM_{2.5}$. Elemental analyses of solid residues and individual residual particles in raindrops were subsequently analyzed by Particle Induced X-ray Emission (PIXE) and Scanning Electron Microscopy (SEM) with Energy Dispersive X-Ray Analysis (EDX), respectively. The raindrop number concentration ($m^{-2}h^{-1}$) tended to drastically decrease as the drop size goes up. Particle scavenging rate, $R_{sca.}$ (%), based on the actual measurement values were 38.7, 69.5, and 80.8% for the particles with 0.3-0.5, 0.5-1.0, and $1.0-2.0{\mu}m$ diameter, respectively. S, Ca, Si, and Al ranked relatively high concentration in raindrops, especially small ones. Most of the element showed a continuous decrease in concentration with increasing raindrop diameter. The source profile by factor analysis for the components of residual particles indicated that the rainfall plays a valuable role in scavenging natural as well as artificial particles from the dirty atmosphere.

• Journal of information and communication convergence engineering
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• 제4권1호
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• pp.46-52
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• 2006

Precipitation measurement with ground-based radar needs an information of the raindrop size distribution (RSD) characteristics. A 10-month dataset was collected in tropical Atlantic coastal zone of northeastern Brazil where the weather radar was installed. The number of drop was mainly recorded in 300 - 500 drop $mm^{-3}$, of which the maximum was registered around 1.1 mm drop diameter.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2002년도 ITC-CSCC -1
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• pp.527-530
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• 2002

The frequencies for HAPS used in fixed wireless access are allocated in the millimeter wave bands. The systems using these frequencies can have a serious impact on the radio communication qualities due to rain. In this paper, we compare the specific rain attenuation using CM(combined) raindrop size distribution with those using different sevral raindrop size distributions for the frequency bands 28/48㎓. The rain attenuations using CM raindrop size distribution for the path between the earth and HAPS platform according to the elevation angle are described.

• 응용통계연구
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• 제18권2호
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• pp.471-485
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• 2005

범주형 자료분석에서 차원축소(collapsibility)는 오즈비로 설명되었다. 실제의 $2{\times}2{\times}K$ 분할표 자료를 이 이론에 적응시켰을 때 오즈비의 값으로 차원축소가 가능한지의 여부를 판단하기는 어렵다. 오즈비를 시각적으로 표현하는 방법 중에서 Doi, Nakamura와 Yamamoto(2001)가 제안한 Contour plot을 통해서 분할표 자료를 설명하는 것은 가능하지만 차원축소의 가능성을 결정하기에는 한계가 있다. 본 연구에서는 오즈비의 신뢰구간을 시각적으로 표현할 수 있는 방법으로 Barrowman과 Myers(2003)가 제안한 Raindrop plot을 이용하여 $2{\times}2{\times}K$ 분할표 자료를 설명할 수 있으며 동시에 차원축소의 가능성을 판단할 수 있는 방법을 제안하고자 한다.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 1999년도 Proceedings of International Symposium on Remote Sensing
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• pp.290-295
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• 1999

Lineament extraction from mountain area often provides valuable geological information. In many cases, the lineaments correspond to a series of continuous large valleys. This paper introduces a new lineament extraction method from Digital Elevation Model (DEM) using Raindrop Tracing Algorithm (RTA). The main advantage of this algorithm over conventional Segment Tracing Algorithm (STA) is that it utilizes DEM directly unlike the STA Which utilizes the shaded relief of DEM. The RTA simulates the real life of raindrops that converge into a large valley. The simulation has been done by sprinkling the randomized raindrops over DEM and counting the number of raindrop path that follows the negative gradient of the DEM. The large counting number indicates the location of a big valley where the raindrops converge. With the help of the counting number array (accumulator array) recording the flowing path information, RTA can produce perfectly unbiased binary image of the lineament.

• 한국우주과학회:학술대회논문집(한국우주과학회보)
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• 한국우주과학회 2003년도 한국우주과학회보 제12권2호
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• pp.35-35
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• 2003

In satellite communication, attenuation, scattering, and depolarization of relatively high frequency waves such as millimeter waves are strongly influenced by rain. In order to study the rain attenuation, we introduce a new theoretical method, which enables us to obtain the reflection and transmission coefficients in arbitrary medium. We adopt this method to examine how the electromagnetic radiation is affected by homogeneous spherical raindrops. It is assumed that the raindrop shape is spherical and linearly locate in one direction. For the radiation of wave in raindrops, we consider the effective permittivity, in which the raindrop is assumed to be spherical. By adopting the invariant imbedding approach, the 1st order differential equations are derived for the reflection and transmission coefficients. We investigate the transmission and reflection of waves for various incident angles when the spherical raindrops are assumed to have random sizes.

• 한국통계학회:학술대회논문집
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• 한국통계학회 2004년도 학술발표논문집
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• pp.175-178
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• 2004

범주형 자료분석에서 차원축소(collapsibility)는 오즈비로 설명되었다. 실제의 $2\times2\timesK$ 분할표 자료를 이 이론에 적용시켰을 때 오즈비의 값으로 차원축소가 가능한지의 여부를 판단하기는 어렵다. 오즈비를 시각적으로 표현하는 방법 중에서 Doi, Nakamura와 Yamamoto(2001)가 제안한 Contour plot을 통해서 분할표 자료를 설명하는 것은 가능하지만 차원축소의 가능성을 결정하기에는 한계가 있다. 본 연구에서는 오즈비의 신뢰구간을 시각적으로 표현할 수 있는 방법으로 Barrowman과 Myers(2003)가 제안한 Raindrop plot을 이용하여 $P_{\lambda,;,T}^M-policy$ 분할표 자료를 설명할 수 있으며 동시에 차원축소의 가능성을 판단할 수 있는 방법을 제안하고자 한다.