• Journal of Korean Society for Atmospheric Environment
• /
• 제24권E2호
• /
• pp.92-101
• /
• 2008

The objective of this study is to evaluate and improve the capability of the Weather Research and Forecasting (WRF) model in simulating fog and visibility in local airports over Korea. The WRF model system is statistically evaluated for the 48-fog cases over Korea from 2003 to 2006. Based on the 4-yr evaluations, attempts are made to improve the simulation skill of fog and visibility over Korea by revising the statistical coefficients in the visibility algorithms of the WRF model. A comparison of four existing visibility algorithms in the WRF model shows that uncertainties in the visibility algorithms include additional degree of freedom in accuracy of numerical fog forecasts over Korea. A revised statistical algorithm using a linear-regression between the observed visibility and simulated hydrometeors and humidity near the surface exhibits overall improvement in the visibility forecasts.

• 한국실내디자인학회논문집
• /
• 제21권5호
• /
• pp.106-113
• /
• 2012

A study on techniques to evaluate auditorium assignment visible efficiency using three-dimensional simulation. The most important thing to be considered is to ensure the visibility to the podium upon assigning auditorium of venues, classrooms or seminar rooms. However, since there are so many variables to be considered such as the form of the stage, the area and height of the stage, size of screen, and the distance and angle of the auditorium from the podium, the methods to assign auditorium are staying at the level of basic for a long time. Thus, in this study, we proposed simulation methodology to quantitatively evaluate the three-dimensional visible efficiency based on Visual Graph Analysis (VGA) theory. After analytical methodology manufactures application, it sets examples of visibility depending on location of screen, visibility depending on degree of height difference and visibility about three-dimensional Mass Zoning like a stage and verifies the efficacy. In addition, based on results, visibility expectation curve is drawn and the method to calculate the stepped height depending on necessary visibility is proposed.

• 대한건축학회논문집:계획계
• /
• 제35권1호
• /
• pp.83-92
• /
• 2019

Advertising signboards are designed for the visibility to affects recall and recognition of costumers. It is well know that the visibility from images is created by the value difference among colors. The research defines whether the background color combination of outdoor signboards is configured to maximize visibility, by a series of color value variation in complex commercial facilities. The subject of study is to examine how the visibility is made by the color combination since visibility cannot be obtained independently. Two steps of analysis were performed to confirm that the color composition of signboards was based on the color value difference. The first is to analyze that the entire colors of signboards are clearly categorized as different value groups. All components of colors, hue, value and chroma had been analyzed by color aesthetic measures to prove that the value variation has the only regularity and the principle of composition. The second step is a further verification with an ample amount of samples to determine whether series of signboards create a value altering pattern. The data for analysis is gained by colorimetric survey and the color data are used for exponentializing the degree of combining, which shows selective affinity between each pair colors.

• 한국도로학회논문집
• /
• 제17권5호
• /
• pp.57-66
• /
• 2015

PURPOSES: Nighttime driving is very different from daytime driving because drivers must obtain nighttime sight-distances based on road lights and headlights. Unfortunately, nighttime driving conditions in Korea are far from ideal due to poor lighting and an insufficient number of road lights and inadequate operation and maintenance of delineators. This study is conducted to develop new standards for nighttime road visibility based on experiments of driver perception for nighttime visibility conditions. METHODS : In the study, perception level and satisfaction of nighttime visibility were investigated. A total of 60 drivers participated, including 34 older drivers and 31 young drivers. To evaluate driver perceptions of nighttime road visibility, fuzzy set theory was used because the conventional analysis methods for driver perception are limited in effectiveness for considering the characteristics of perception which are subjective and vague, and are generally expressed in terms of linguistic terminologies rather than numerical parameters. RESULTS : This study found that levels of nighttime visibility, as perceived by drivers, are remarkably similar to their satisfactions in different nighttime driving conditions with a log-function relationship. Older drivers evaluated unambiguously degree of nighttime visibility but evaluations by young drivers regarding it were unclear. CONCLUSIONS : A minimum value of brightness on roads was established as YUX 30, based on final analyzed results. In other words, road lights should be installed and operated to obtain more than YUX 30 brightness for the safety and comfort of nighttime driving.

• 교육녹색환경연구
• /
• 제11권1호
• /
• pp.23-31
• /
• 2012

The number of school crime has grown continuously for last ten years and its intensity also has reached to serious condition. The concept of CPTED(Crime Prevention through Environmental Design) needs to be focused for improving school environment regarding this context. The exterior space of school environment is variously exposed to school crimes committed by colleague students and also intruders. From the perspective of school CPTED, Natural surveillance as one of the practical strategies requires the micro-scale analysis which clarifies local visibility at each different school exterior space. Thus, the purpose of this research is to develop the analysis method clarifying visibility condition at exterior space of school environment, which supports finding the condition of natural surveillance. The programmed analysis algorithm generated quantitative results clarifying Degree for static visibility and Clustering Coefficient for user tracking visibility. The result of this study produced the analysis method feasible to clarify weak natural surveillance conditions at school exterior spaces. Also, it is expected that the developed analysis method will be used to improve the layout of school exterior space from the perspective of CPTED.

• 한국염색가공학회지
• /
• 제33권4호
• /
• pp.288-301
• /
• 2021

The purpose of this study was to verify the degree of visibility of FOLED (fiber optic light-emitting diode) materials applied to safety-enhancing clothes of micro-mobility users during the day and night by conducting an empirical test targeting 50 people in their teens, 20's, 30's, 40's, and 50's or older. First, the results of the visibility test at 10 m-intervals from 10 to 70 m based on the clothes sample showed that the light detection of FOLED material was very good without daytime or night-time distinction. Second, the results of directional sign detection of FOLED were confirmed to be very high without any daytime or night. Third, the results of identifying a pictogram design showed that the distance was shorter than that of light detection or directional indication. However, the FOLED pictogram design could be confirmed at a distance of 50 m or less. Therefore, if a clothes product using FOLED material is worn and micro-mobility is used, the experimental results indicate that safety will be sufficiently secured due to the excellent visibility.

• Imaging Science in Dentistry
• /
• 제31권3호
• /
• pp.153-158
• /
• 2001

Purpose : To determine the head position that the superior border of the mandibular canal as well as mental foramen can be more clearly visualized in panoramic radiography Materials and Methods : Ten dry mandibles were radiographed bilaterally using PM 2002 CC panoramic machine. A 20 mm thick aluminium filter was added to the slit collimator to obtain radiographs with acceptable density. The specimens were tilted by 2, 4, 6, 8, and 10 degrees downward with and without radiopaque markers. Radiopaque markers were inserted into the mandibular canals and the mental canals of each side of the specimens to serve as reference image when assessing the radiographs. The visibility of the mandibular canal and the mental foramen was estimated by 4 observers on all radiographs. The obtained results were analyzed statistically. Results: Mandibular canals were significantly more clearly visible in the radiographs with 4 and 6 degree downward position on both sides (P<0.05). Mental foramens were significantly more clearly visible in the radiographs with 4, 6, and 8 degree downward on right side and 6 degree downward on left side (P<0.05). There was not significant difference between right and left sides. Conclusion: Panoramic radiographs with 4 to 6 degree downward tilting could be valuable in locating the mandibular canal as well as the mental foramen.

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

• 대한지리학회지
• /
• 제38권4호
• /
• pp.478-489
• /
• 2003

기존의 국내에서 안개 관련된 연구는 안개 자체에 대한 연구와 안개의 지역적인 분포에 대한 연구가 그 주류를 이루어 왔다. 본 연구는 도로상에서 시정을 저하시켜서 안전한 운행에 지장을 주고 교통-사고를 유발시킬 수 있는 안개를 도로위험안개로 정의하고 그 위험정도를 정량적으로 나타낼 수 있는 위험안개 발생지표를 개발하였다. 이 지표는 안전운행에 영향을 주고 사고를 유발시킬 수 있는 다양한 사항, 즉 안개의 발생빈도를 나타내는 안개발생일수, 안개의 지속시간, 시정거리 등을 고려하여 개발되었으며 개발된 지표에 근거하여 국내의 위험안개발생지역의 분포와 그 위험정도를 파악할 수 있었다. 본 연구는 한국의 안개특성을 고려하여서 위험정도를 정량화하고 가중치를 개발한 국내 최초의 연구라는 점에서 의의가 있고 개발된 지표에 근거한 위험지역의 안전관리 대상 선정과 그에 대한 안전시설물의 설치, 사고위험지점의 원인분석 및 그에 대한 대처방안 등을 수립하는데 유용한 자료로 사용될 수 있다. 더 나아가, 외국의 경우와 같이 도로의 노선선정시 위험안개발생지표가 높은 지역에 대해서는 노선의 변경 또는 노선선택 후 그에 대한 대책수립과 같은 적극적인 안전관리가 가능하다.

• 대한인간공학회지
• /
• 제29권4호
• /
• pp.575-584
• /
• 2010

The aim of study is to suggest the design procedure of automobile headlamp by considering driver's experience in regard of the visibility and glare during nighttime driving. The characteristics of driver were investigated in terms of the drivers' cognitive ability and reaction time, headlamp specification and visibility, light source and glare. And, the degree of visual discomfort was categorized and recognized as a tool to represent the subjective user experience. The UX point of view was stated when the existing results were seemingly lacking of it. The visual comfort and safety of elderly drivers were also discussed by reviewing the studies of ageing regarding the visibility and driving responses. Finally, this study suggested how to reduce the negative effect of nighttime driving due to the height of headlamp, angle of lighting, color spectrum, discomfort glare, source of light by using the UX perspective and methodology.