• Journal of Environmental Science International
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• v.16 no.5
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• pp.583-591
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• 2007

In this study, meteorological characteristics concerning the occurrence of fog are analyzed using 4-years (2000-2003) data at Chuncheon. From the analysis of meteorological characteristics, the fog at Chuncheon occurred before sunrise time and disappeared after that time and lasted for 2-4 hours. When fog occurred, on the whole, wind direction was blew the northerly and wind speed was below 2.1 m/s. Especially, about 42 % of foggy day fell on the calm($0{\sim}0.2m/s$) conditions. The difference between air temperature and dew point temperature near the surface were mainly less than $2^{\circ}C$. For the lack of water surface temperature, the water sur-face temperature was calculated by using Water Quality River Reservoir System (WQRRS). In Chuncheon, there is close correlation between the frequency of fog day and outflow from Soyang reservoir and high frequency of occurrence due to the difference between air and cold outlet water temperature.

• Proceedings of KOSOMES biannual meeting
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• 2004.11a
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• pp.123-127
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• 2004

It is known that cold water appears and fog frequently forms in the southwest coastal waters of Korea in summer. The authors investigate the time and place. of cold water existence, and also whether the cold water affects the occurrence of fog formation. As a result, cold water begins to appear around Daeheugsando at the early summer. It gets colder with times and cold water area moves toward southwest of Jindo in mid-summer, then disappears in this area around mid-Oct. Fog mostly forms in April through August and most frequently occurs at Chukdo(Jindo) where sea surface temperature shows lower than that at the adjacent area. Accordingly it is taken that the cold water is considerably contributed to form the dense and frequent fog around Jindo area.

• Korean Journal of Optics and Photonics
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• v.8 no.5
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• pp.426-430
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• 1997

A signal processor is implemented to verify the possibility of a closed-loop signal processing for the open-loop fiber-optic gyroscope (FOG). As an all-digital implementation of phase tracking scheme, it does analog-to digital conversion of the detector output and signal processing all-digitally thereafter for a noise-immune FOG signal processor. It has a potential of 36-bits resolution in the $2\pi$ range which is best in the number and sets no limit in the magnitude of the phase shift. The new signal processor was tested on an all-fiber gyroscope and turned out to have a resolution of $3\mu$rad(corresponds to 0.74 deg/hr), which is good enough to measure the Earth's rotation rate.

• Journal of Environmental Impact Assessment
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• v.12 no.2
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• pp.109-120
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• 2003

This paper examined the impacts of dam construction on fog characteristics over surrounding areas. Juamdam which only supplies the water for use and Chungjudam which generates electricity were selected. The number of foggy days, fog occurrence and dissipation time and the differences of each lake water temperature and air temperature at Sunchun and Chungju were analyzed. After the construction of dam, the relative humidity and water vapor pressure were decreased at Sunchun and Chungju. The number of foggy days did not increase at Sunchun while largely increased at Chungju. Just because Juamdam were contained water, the water vapor pressure at surrounding areas of the weather station were largely decreased. It delayed the time of fog occurrence by bringing out the decrease of steam fog. The foggy days increased over the Chungju area due to the difference between air and cold outlet water temperature. The increase of foggy days mainly resulted from evaporation during colder seasons and from the temperature inversion over the water surface during warmer seasons.

• Magazine of the Korean Society of Agricultural Engineers
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• v.41 no.1
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• pp.60-71
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• 1999

This study was performed to improve underirable warm greenhouse environment by fog cooling system in summer season. The resultsof droplet size analysis and cooling effects for fog cooling system are summarized as follows ; 1. At the pump pressure of 70kgf/$\textrm{cm}^2$ , the mean (SMD) drop size was 22.6${\mu}{\textrm}{m}$ and the maximum and minimum drop size was 45.68${\mu}{\textrm}{m}$ and 1.73${\mu}{\textrm}{m}$ , respectively, and almost all of the drop size was less than 40${\mu}{\textrm}{m}$. 2. The temperature of fog cooling greenhouse with 60% shading was dropped more than 2$^{\circ}C$ below the ambient temperature , while the greenhouse temperature without shading was 1$^{\circ}C$ higher than the ambient temperature. 3. It was found that fog spraying intervals were significantly influential on cooling effect. 4. When the greenhouse was ventilated sufficiently by natural vent system, green house temperature could be maintained by 2.5$^{\circ}C$ lower than the ambient temperature, while it was difficult to drop the greenhouse temperature below ambient temeperature without sufficient ventilation. 5. It was found that the temperature of experimental greenhouse could be maintained 3$^{\circ}C$ to 14$^{\circ}C$ lower that of control greenhouse though there were variations depending on experimental and weather conditions.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.11 no.10
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• pp.758-762
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• 1998

Electrical conduction property of insulator surface is most important factor to assess the insulation performances of outdoor insulating materials. In this paper, contamination performance of the materials to be used for outdoor insulator such as porcelain, EPDM, silicone rubber was discussed by measuring properties of average leakage current and scintillation discharge pulses under salt fog conditions. The fog was applied by nozzle in chamber and fogging fluids were deionized distilled water, 0.5wt% NaCI solution and 2wt% NaCl solution. The average leakage current showed linearly with applied voltage at dry and clean surface condition. The magnitude of leakage current was almost same at different kinds of samples. In case of deionized distilled water fog, the characteristics of leakage current and applied voltage were much different to those in case of dry and clean condition with 2wt% salt fog. In case of slat fog pollution condition, the leakage current was increased above critical voltage. the scintillation discharges were also activated at the level. The leakage current and scintillation discharges were increased with increasing pollution degree. The resistance to pollution properties of silicone rubber appeared excellent among them.

• Smart Media Journal
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• v.8 no.1
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• pp.35-42
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• 2019

With IoT device technology developments, such devices now can perceive the surrounding environment and operate upon the condition, but a method for efficiently processing an enormous amount of IoT device data is required. The existing cloud computing has a transmission delay problem due to load and distance. Fog Computing, an environment to control IoT devices, therefore, emerged to solve this problem. In Fog Computing, IoT devices are located close to each other to solve the shortcomings of the cloud system. While many earlier studies on Fog Computing for IoT mainly focus on its structure and framework, we would like to propose an integrated Fog Computing platform that monitors, analyzes, and controls IoT devices.

• ETRI Journal
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• v.44 no.4
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• pp.686-694
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• 2022

Fog screens offer a great advantage to be used as scattering screens in three-dimensional displays. In the absence of a fixed rigid form, fog screens work as screens without any physical obstruction. The density of water droplets can be regulated to adjust the screen's transparency and scattering level. This study proposes a method for crosstalk reduction between adjacent viewing windows by decreasing the divergence of view of the projector, with concentration lenses. By applying the Scheimpflug principle, we also reduce the keystone effect, which occurs when the fog screen is slanted with respect to the optical axis. In this study, we have realized a tabletop multiview fog display without any structures on the table and established that the proposed method is feasible for decreasing crosstalk effectively.

• Journal of the Korean Society of Visualization
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• v.22 no.1
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• pp.34-39
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• 2024

With the fine particulate matter (PM) poses a serious threat to public health and the environment. The ultrafine PM in particular can cause serious problems. This study investigates the effectiveness of a submicron dry fog system in removing fine PM. Two methods are used to create fine dust particles: burning incense and utilizing an aerosol generator. Results indicate that the dry fog system effectively removes fine dust particles, with a removal efficiency of up to 81.9% for PM₁₀ and 61.9% for PM_2.5 after 30 minutes of operation. The dry fog, characterized by a mean size of approximately 1.5 ㎛, exhibits superior performance in comparison to traditional water spraying methods, attributed to reduced water consumption and increased contact probability between water droplets and dust particles. Furthermore, experiments with uniform-sized particles which sizes are 1 ㎛ and 2 ㎛ demonstrate the system's capability in removing ultrafine PM. The proposed submicron dry fog system shows promise for mitigating fine dust pollution in various industrial settings, offering advantages such as energy consumption and enhanced safety for workers and equipment.

• Journal of Korean Society of Forest Science
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• v.96 no.6
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• pp.676-683
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• 2007

In an attempt to develop an efficient method for the propagation of mature Prunus yedoensis (45 to 55 years old), green wood cuttings from normal branch and sprouts branch were treated with three different kinds of auxin (Rootone < 1-naphthylacetamide 0.4% >, IBA 100 ppm, and control and two different kinds of fog systems (0.9 L/min. and 0.54 L/min.). The Rootone treatment showed higher values in the percentage of rootings (PR) and the mean number of roots per cutting (NR) than the IBA treatment in the early stage. However, in the late stage, the values of PR and NR in the Rootone treatment become lower than those in the IBA 100 ppm treatment. On the other hand, root development ceased 62 days after taking cuttings for all of the treatments. The IBA 100 ppm treatment showed the best performance in root development (PR= 89.5%, NR = 6.5, LR=6.4 cm). The values of PR (76.5%) and NR (6.4) in the 0.9 L/min. of fog treatment was higher than those (PR = 71.7% and NR = 5.4) in the 0.54 L/min. of fog treatment. The cuttings from sprouts (PR: 74.8%, NR: 5.9, LR: 5.7 cm) showed slightly better performance in rooting rate that the cuttings from shoots (PR : 73.3%, NR: 5.9, LR: 5.4 cm). Statistically significant interactions were presented among most of the different combinations of three factors (auxin treatments, fog treatments, and types of cuttings). The PR showed the highest value of 98.0% in the combination of cuttings of shoots+IBA 100 ppm+0.54 L/min. fog treatments. In case of NR, the cuttings from normal branch showed a higher value than the cuttings from sprouts branch under the fog treatment of 0.9 L/min., while this tendency was reversed under the fog treatment of 0.54 L/min.. The perigon development of roots, which reflects the number and the direction of roots, was best in the IBA treatment (85.6%).