• Journal of Korean Society for Atmospheric Environment
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• v.25 no.4
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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.

• Journal of Korea Foresty Energy
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• v.19 no.1
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• pp.20-29
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• 2000

This study was carried out to investigate the effects of shading on the growth of 1 -year-old seedlings of Cornus controversa. The height growth was highest in relative light intensities of 100% and 50%, but relative growth rate in 50% was higher than that in 100% treatment. The growth did not occur under 9% relative light intensity. The root collar diameter growth at different light intensities is similar to height growth. The leaf area was highest in 50% relative light intensity, and the leaf area under the light intensity was small compared with the control. SLA and LAI of seedlings increased with decreasing relative light intensity. The LAR and LWR of seedlings increased with decreasing light intensity, but LWR decreased at 9% relative light intensity. The dry weight of root, stem, leaf and branch, and the number of branch and leaf decreased with decreasing relative light intensity. T/R ratio was highest in 17% and 30% relative light intensity. Lateral root growth decreased with decreasing light intensity except for that in 50% light intensity.

• Proceedings of the KSR Conference
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• 2003.05a
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• pp.257-262
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• 2003

Now, the population and economical power is deeply concentrated to Seoul-metropolitan region, therefoere the provinces is so lagging behind and the country cannot get balance development. And, like metropolitan region, the more outer the living area of local wide-area city is spreading, the more serious wide-region transportation problems are. But the railroads near wide-area city fun seldom commuter train, so they cannot absorb the transportation demand of wide-area city metropolitan region. To solve above transportation problem, local wide- area cities try to make a subway or a light rail transit. But it is so difficult because the limit of public finance and original small capacity of light rail. In the paper, I propose 'Local city wide-area electric railways' system of the consortium of 'Local wide-city and province transportation union', Korean National Railroad (KNR) and local capital. A 'Local wide-city and province transportation union' operates commuter railways directly using the facilities of KNR, and local capital invests to the stations of above railways system. Therefore the commuter railway system around local wide-city region will be constructed quickly and the stations will be the strong point of local development and investment.

• KIEAE Journal
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• v.10 no.2
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• pp.71-78
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• 2010

Spill light by street lighting is a kind of light pollution creating cozy night atmosphere, interfere visual private and cause insomnia at night. This study was to survey light trespass of the windows in residential buildings. According to outdoor lighting control guidance in Seoul, three different areas were selected to investigate the trespass light to windows. The results were as follows: 37% of the buildings of 386 buildings were influenced by street lighting, and 47% of windows were occurred light trespass. Therefore, the street lighting affected light trespass at night in survey area. The main reasons of light trespass were luminaire type, luminaire pole height, and street width. For protecting the light trespass to windows, it is necessary to non-cutoff fixture to full cutoff fixture by the street width.

• Proceedings of the Korean Fiber Society Conference
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• 2003.04a
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• pp.358-359
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• 2003

Organic light-emitting device have attracted much interest due to their potential application in large area, full color, flat panel displays. Poly(p-phenylene)(PPP), as a blue light-emitting materials, have studied in our previous report. Thus, we selected poly(p-phenylene) (PPP) to fabricate the organic light-emitting filaments(OLEF) [1-2]. In this paper, we fabricated an organic light-emitting filaments(OLEF), which can be woven into fabric. The key concept was flexibility in one-dimensional structures. (omitted)

• Proceedings of the KIEE Conference
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• 2008.09a
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• pp.140-143
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• 2008

In this study, it was studied about the improved road light design for drivers and pedestrians using ray- or reverse ray-tracing method. Many of conventional road lights are not suitable for drivers and pedestrians because it has some serious problems such as glare effect or randomicity of illuminated areas. It was oriented from customary design method which was pointed at simple target such as luminance or electrical power. But it was not truth any more that the high luminance or electrical power consumption mean more bright and good mad light. We studied ray-tracing method for road light reflector design to get the several goals. It means that good road light has easy for drivers and Pedestrians eyes and illuminating objects on the road clearly. So, we set the design targets such as uniformity on the road area per one road light, shading angles and continuous luminance uniformity on the long distance road. We designed ideal road light conditions using ray-tracing method. We set the height of drivers and pedestrians eyes and calculated design guideline to make above design targets. Then we designed road light reflector using reverse ray-tracing method. And we achieved same luminance on the road almost half power consumption because we reduced loss of light. We achieved ideal design guide as 75 degrees of shading angles and 0.5 of luminance uniformity on the road area. Finally, we suggested reflector design for 250 watts power consumption CDM light source.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.58 no.3
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• pp.347-350
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• 2009

In this study, it was studied about the improved road light design for drivers and pedestrians using forward or reverse ray-tracing method. Many of conventional road lights are not suitable for drivers and pedestrians because it has some serious problems such as glare effect or randomicity of illuminated areas. It was oriented from customary design method which was pointed at simple target such as luminance or electrical power. But it was not truth any more that the high luminance or electrical power consumption mean more bright and good road light. We studied ray-tracing method for road light reflector design to get the several goals. It means that good road light has easy for drivers and pedestrians eyes and illuminating objects on the road clearly. So, we set the design targets such as uniformity on the road area per one road light, shading angles and continuous luminance uniformity on the long distance road. We designed ideal road light conditions using ray-tracing method. We set the height of drivers and pedestrians eyes and calculated design guideline to make above design targets. Then we designed road light reflector using reverse ray-tracing method. And we achieved same luminance on the road almost half power consumption because we reduced loss of light. We achieved ideal design guide as 75 degrees of shading angles and 0.5 of luminance uniformity on the road area. It is superior than conventional road light ability such as 0.35 of luminance uniformity of 400 watts power consumption lamp. Finally, we suggested reflector design for 250 watts power consumption CDM Iight source.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.11a
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• pp.327-328
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• 2008

In this study, it was studied about the improved road light design for drivers and pedestrians using ray- or reverse ray-tracing method. Many of conventional road lights are not suitable for drivers and pedestrians because it has some serious problems such as glare effect or randomicity of illuminated areas. It was oriented from customary design method which was pointed at simple target such as luminance or electrical power. But it was not truth any more that the high luminance or electrical power consumption mean more bright and good road light. We studied ray-tracing method for road light reflector design to get the several goals. It means that good road light has easy for drivers and pedestrians eyes and illuminating objects on the road clearly. So, we set the design targets such as uniformity on the road area per one road light, shading angles and continuous luminance uniformity on the long distance road. We designed ideal road light conditions using ray-tracing method. We set the height of drivers and pedestrians eyes and calculated design guideline to make above design targets. Then we designed road light reflector using reverse ray-tracing method. And we achieved same luminance on the road almost half power consumption because we reduced loss of light. We achieved ideal design guide as 75 degrees of shading angles and 0.5 of luminance uniformity on the road area. Finally, we suggested reflector design for 250 watts power consumption CDM light source.

• Tribology and Lubricants
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• v.15 no.1
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• pp.29-38
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• 1999

In recent years, the tribological behavior of coated ceramic material has been the issue of much interest. Particularly, the understanding of the tribological performance of thin film under light load is important for its potential in applications of MEMS. The friction and wear behavior of ceramic material that occur at light load depends on several factors such as surface roughness, contact area and material properties. In this work, the tribological behavior of coated silicon under light load and low speed was investigated. Particularly, the effects of coated materials, humidity and undulated surface were also studied. The results show that the effect of humidity on fiction was influenced by the apparent area of contact between the two surfaces. Also both adhesive and abrasive wear occurred depending on the sliding condition. Finally, undulations on the silicon wafer were found to be effective in trapping wear particles and resulted in the reduction of friction.

• Journal of the Korean Institute of Navigation
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• v.16 no.1
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• pp.65-75
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• 1992

The Waterway System for the Very Large Ships is One of the Important System connected between Marine Transport System and Exclusive Terminal. This study analyzed the Turning Configurations and Placement of Fairway Buoys in Waterway at the Port of Kwangyang to make Optimal Suggestion of for Ship's Safe Navigation. The following Conclusions are drawn : 1) In Area Section A, Starboard hand Buoy No14 should be changed its Location and Light Rhythms, and Buoy Nos.13 '||'&'||' 16 are required their Light Rhythms to be changed. 2) Especially in Area Section B located before the Turning Basin, The Location and Light Rhythms of Nos.20 '||'&'||' 22 buoys at Starboard Hand should be changed, Port Hand No.21 also should be done, and East Cardinal Buoy located between Nos.21and 23 should be changed its Light Rhythms, or removed if possible. 3) Buoy no.19 of Lateral Port Hand in Section B should be changed "Preferred Channel to Startboard" to distinguish Main Channel from Secondary One.