• Journal of Information Processing Systems
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• 제13권4호
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• pp.818-833
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• 2017

This paper introduces a new algorithm that renders motion blur using triangular motion paths. A triangle occupies a set of pixels when moving from a position in the start of a frame to another position in the end of a frame. This is a motion path of a moving triangle. For a given pixel, we use a motion path of each moving triangle to find a range of time that this moving triangle is visible to the camera. Then, we sort visible time ranges in the depth-time dimensions and use bitwise operations to solve the occlusion problem. Thereafter, we compute an average color of each moving triangle based on its visible time range. Finally, we accumulate an average color of each moving triangle in the front-to-back order to produce the final pixel color. Thus, our algorithm performs shading after the visibility test and renders motion blur in real time.

• 한국대기환경학회지
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• 제25권4호
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• pp.325-338
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• 2009

National parks provide recreation, health, and science to human being. The provision of beautiful landscape view of the national park improves an economic and social phase of a nation. However, visibility impairment frequently occurred in the national park area of Gyeongju. The purpose of this study is to investigate the physical and the chemical characteristics of visibility reduction observed at the national park area of Gyeongju. Optical, chemical, meteorological characteristics and scenic monitoring were performed at the visibility monitoring station of Gyeongju University located at the Seoak section of Gyeongju national park from April 28 to May 9, 2008. Light extinction, light scattering, and light absorption coefficients were continuously measured using a transmissometer, a nephelometer, and an aethalometer, respectively. In order to investigate the impact of aerosol chemistry on visibility impairment, size-resolved aerosols were collected at intervals of 2-hour (from 8 A.M. to 6 P.M.) and 14-hour (from 6 P.M. to 8 A.M.) interval each sampling day. The average light extinction coefficient and the average visual range were measured to be $270{\pm}135\;Mm^{-1}$ and $14.5{\pm}6.3\;km$ during the intensive monitoring period, respectively. It was revealed that sulfate particle was the largest contributor to the light extinction under hazy condition. Organic mass accounted for about 26% of the average light extinction. The mass extinction efficiencies for $PM_{1.0}$, $PM_{2.5}$, and $PM_{10}$ were estimated to be 9.0, 4.7, and $2.7\;m^2\;g^{-1}$ under the consideration of water growth function of hygroscopic aerosols, respectively.

• 접착 및 계면
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• 제17권3호
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• pp.110-116
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• 2016

야간 우천시 수막에 의한 차선의 재귀반사 효율 감소로 운전자의 시인성이 저하되고 있으며 이로 인해 많은 사고가 발생한다. 시인성을 높이기 위해 메틸메타크릴레이트의 현탁중합 시 소수성으로 표면이 개질된 $SrAl_2O_4:Eu^{2+}$,$Dy^{3+}$ 축광 물질을 도입하고 이를 캡슐화하였다. 표면 개질에 사용된 물질과 라디칼 개시제의 종류, 사용된 축광 물질의 양, 그리고 캡슐의 입도가 캡슐 내부의 축광 물질 함량($W_{TGA}$)에 미치는 영향을 TGA를 사용하여 분석하였다. 그 결과 축광 물질의 함량은 7~81 wt%까지 넓은 분포를 나타내었으며, 이러한 결과는 현탁중합이 넓은 함량 범위의 축광 물질을 캡슐화하는데 적합한 것을 의미한다. 축광 물질의 함량이 낮은 경우에는 캡슐의 입도가 감소함에 따라 $W_{TGA}$이 증가하였으나, 축광 물질의 함량이 높을 때에는 캡슐의 입도에 별 영향을 받지 않았다. 축광 캡슐 중 지름 $425{\sim}710{\mu}m$의 축광 캡슐을 활용하여 형광 차선 시편을 제작하였으며 LED램프를 20 min 동안 조사한 후 광원을 제거하였을 때, 100 s 동안 약 $300mcd/m^2$ 이상의 휘도를 유지했다. 이러한 결과로 미루어 보아 제조된 축광 캡슐은 차선 위의 유리 비드를 대체하기에 충분한 가능성을 가짐을 알 수 있었다.

• 한국정밀공학회지
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• 제34권4호
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• pp.259-264
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• 2017

Spectrally resolved interferometry (SRI) is an attractive technique to measure absolute distances without any moving components. In the spectral interferogram obtained by a spectrometer, the optical path difference (OPD) can simply be extracted from the linear slope of the spectral phase. However, SRI has a fundamental measuring range limitation due to maximum and minimum measurable distances. In addition, SRI cannot distinguish the OPD direction because the spectral interferogram is in the form of a natural sinusoidal function. In this investigation, we describe a direction determining SRI and propose the optimal conditions for determining OPD direction. Spectral phase nonlinearity, caused by a dispersive material, effects OPD direction but deteriorates spectral interferogram visibility. In the experiment, various phase nonlinearities were measured by adjusting the dispersive material (BK7) thickness. We observed the interferogram visibility and the possibility of direction determination. Based on the experimental results, the optimal dispersion conditions are provided to distinguish OPD directions of SRI.

• Journal of Astronomy and Space Sciences
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• 제28권4호
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• pp.319-332
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• 2011

The objectives of this study are to analyze the satellite visibility at the randomly established ground sites, to determine the five optimal ground sites to perform the optical surveillance and tracking of domestic satellites, and to verify the acquisition of the optical observation time sufficient to maintain the precise ephemeris at optimal ground sites that have been already determined. In order to accomplish these objectives, we analyzed the visibility for sun-synchronous orbit satellites, low earth orbit satellites, middle earth orbit satellites and domestic satellites as well as the continuous visibility along with the fictitious satellite ground track, and calculate the effective visibility. For the analysis, we carried out a series of repetitive process using the satellite tool kit simulation software developed by Analytical Graphics Incorporated. The lighting states of the penumbra and direct sun were set as the key constraints of the optical observation. The minimum of the observation satellite elevation angle was set to be 20 degree, whereas the maximum of the sun elevation angle was set to be -10 degree which is within the range of the nautical twilight. To select the candidates for the optimal optical observation, the entire globe was divided into 84 sectors in a constant interval, the visibility characteristics of the individual sectors were analyzed, and 17 ground sites were arbitrarily selected and analyzed further. Finally, five optimal ground sites (Khurel Togoot Observatory, Assy-Turgen Observatory, Tubitak National Observatory, Bisdee Tier Optical Astronomy Observatory, and South Africa Astronomical Observatory) were determined. The total observation period was decided as one year. To examine the seasonal variation, the simulation was performed for the period of three days or less with respect to spring, summer, fall and winter. In conclusion, we decided the optimal ground sites to perform the optical surveillance and tracking of domestic satellites and verified that optical observation time sufficient to maintain the precise ephemeris could be acquired at the determined observatories.

• 전자공학회논문지B
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• 제31B권8호
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• pp.160-171
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• 1994

The wide dynamic range and severely attenuated contrast in mediastinal area appearing in typical chest radiographs have often caused difficulties in effective visualization and diagnosis of lung diseases. This paper proposes a new adaptive image enhancement technique which potentially solves this problem and there by improves observer performance through image processing. In the proposed method image processing is applied to the chest radiograph with different processing parameters for the lung field and mediastinum adaptively since there are much differences in anatomical and imaging properties between these two regions. To achieve this the chest radiograph is divided into the lung and mediastinum by gray level thresholding using the cumulative histogram and the dynamic range compression and local contrast enhancement are carried out selectively in the mediastinal region. Thereafter a gray scale transformation is performed considering the JND(just noticeable difference) characteristic for effective image displa. The processed images showed apparenty improved contrast in mediastinum and maintained moderate brightness in the lung field. No artifact could be observed. In the visibility evaluation experiment with 5 radiologists the processed images with better visibility was observed for the 5 important anatomical structures in the thorax.

• 한국의류학회지
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• 제22권5호
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• pp.597-606
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• 1998

The purposes of the study were 1) to evaluate the visual image of colored Korean traditional dress for woman 2) to analyze the colors and, color combinations effect on the image perception using gestalt theory. The research method was a quasi-experimental with a between subjects design. The experimental materials developed for the study were a set of stimuli and a response scale. The stimuli was consisted of 17 drawings of females wearing Korean tradinational dress, by using CAD simulation. A response scale consisted of semantic differential scales. The subjects were 1138 undergraduate students of Taejon city, Chungnam province and Chungbuk province. Their responses to the semantic differential scales were analyzed using factor analysis, one-way ANOVA, Duncan's multiple range test, 1-test. Results were as follows; 1) The image of the stimulus was consisted of the 4 different dimensions.(sociability, evaluation, visibility, attractiveness) 2) Clothing colors had significant effects on image perception of the evaluation dimension, visibility dimension and attractiveness dimension in the mono-color set. The blue showed the most positive image on the evaluation dimension, and the yellow and the gray showed negative image on the same dimension. The yellow showed the most salient image and the gray showed the least salient image on the visibility dimension. The red showed the most attractive image and the green showed the least attractive image on the attractiveness dimension. 3) In hi-color set stimulus, the perceived image was influenced by color combinations. The yellow blouse-the red skirt set showed the most sociable image on the sociability dimension. The blue blouse-the green skirt set showed the most positive image on the evaluation dimension. The yellow blouse-the red skirt set showed the most salient image and the blue blouse-the green skirt set showed the least salient image on the visibility dimension. And the red blouse-the yellow skirt set showed the most attractive image on the attractiveness dimension. On conclusion the visual image of Korean traditional dress wearer was affected by dress colors and color combinations.

• 한국표면공학회지
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• 제56권2호
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• pp.152-159
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• 2023

The night visibility of pavement is being considered as a global issue in the field of traffic safety. Although the spreading glass beads on the lane paints has been mainly used to secure night-visibility by utilizing the effect of retroreflection, obvious shortcoming of this method is that retroflection does not occur in the range where the headlights do not reach the glass beads. The use of functional paints including phosphorescent constituents could be a solution for overcoming fore-mentioned problem. SrAl₂O₄ based chemicals have not only good phosphorescent property, but also are chemically stable compared to existing ZnS based materials. However, this chemicals also need the improvement due to slightly reduced luminous effect in time. Herein, we developed novel paints showing enhanced phosphorescent properties by putting rare earth elements such as Eu, Dy and Y into SrAl₂O₄. These prepared phosphorescent pigments have displayed improved properties in terms of durability and long afterglow. For instance, the property of afterglow has been persisted after 5 hours with luminace of 20.6 mcd/m².

• 천문학회보
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• 제40권1호
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• pp.54.1-54.1
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• 2015

We report results of investigation of amplitude calibration for very long baseline interferometry (VLBI) observations with Korean VLBI Network (KVN). Amplitude correction factors are estimated based on comparison of KVN observations at 22 GHz correlated by Daejeon hardware correlator and DiFX software correlator in Korea Astronomy and Space Science Institue (KASI) with Very Long Baseline Array (VLBA) observations at 22 GHz by DiFX software correlator in National Radio Astronomy Observatory (NRAO). We used the observations for compact radio sources, 3C 454.3 and NRAO 512 which are almost unresolved for baselines in a range of 350-477 km. VLBA visibility data of the sources observed with similar baselines as KVN are selected, fringe-fitted, calibrated, and compared in their amplitudes. We found that visibility amplitudes of KVN observations should be corrected by factors of 1.14 and 1.40 when correlated by DiFX and Daejeon correlators, respectively. These correction factors are attributed to the combination of two steps of 2-bit quantization in KVN observing systems and characteristics of Daejeon correlator.

• 한국안전학회지
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• 제22권5호
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• pp.21-26
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• 2007

The computer program is developed to simulate the evacauation time for a building which is made geometrically complex. The program is intended for use both as a search and a design tool to analyze the evacuation safety through a wide range of structure environments. The computer program has a function of importing FDS's result to each individual resident in the building. These attributes include a walking speed reduction by producing visibility reduction for each person on the fire. $A^*$ pathfinding algorithm is adopted to calculate the simulation of escape movement, overtaking, route deviation, and adjustments to individual speeds due to the proximity of crowd members. Finally, a case study for a theater is presented to compared the calculated evacuation time with SIMULEX in detail. This program contribute to a computer program that evaluates the evacuation time of individual occupants as they walk towards, and through the exits especially for building, underground spaces like a subway or tunnel.