• Journal of Korean Society for Atmospheric Environment
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• v.8 no.1
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• pp.45-51
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• 1992

A study on acidity in fog, dew and frost was carried out. Samples were taken during May 1990-February 1991 at two sites in Chongwon, Choongbook. The acidity of dew and of fog collected from grass at site A was 4.89 and 5.46, respectively. Dew in summer showed very strong acidity. The volume of dew deposited on grass was much less than the volume of rain, but dew is effective to diffuse acid predursors and acid materials. Dew and fog can remove more effectively atmospheric acid materiasl deoposited on grass by diurnal turbulent motion rather than direct absorption of acid predursors and materials in the atmosphere. In a polluted area, acidic dew and fog can be occurred by the direct absorption and oxidation of acidic predursors in the atmosphere as well as the role of wet removal on grass surface. Acidity of frost collected on teflon surface showed little difference to acidity of dew and fog on teflon surface. This suggests a similar absorption mechanism of atmospheric precursors and materials into dew and frost in the atmosphere. Strong acidity in dew, fog and frost appeared to occur from local pollution sources of several ten kilometres. In particular, strong acidity in dew, fog, and frost together with acid rain can accelerate a damage in ecosystems. Discussion is made on scientific analyses and seasonal variations of acidity of fog, dew and frost. A mechanism on acidification of fog, dew and frost is also discussed.

• International Journal of Highway Engineering
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• v.15 no.5
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• pp.195-202
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• 2013

PURPOSES : This study analyzed the regional dew possibility in road sign using meteorological data. METHODS : Four years of meteorological data such as temperature, humidity, dew point, wind velocity were collected and analyzed. As a result of literature review, dew was frequent in large diurnal range, high humidity and weak wind. So, dew possibility was analyzed by (temperature-dew point ${\leq}1^{\circ}C$ and wind velocity ${\leq}$ 1.5m/s). RESULTS : The possibility was analyzed for each meteorological observation point and the point of Suncheon and Bonghwa were selected as the most likely points of dew in road sign. The area of East Coast, Kyungbuk and Kyungnam were relatively low potential. CONCLUSIONS : Alternative with high effect of preventing dew should be selected in high possibility dew area despite of low economics.

• International Journal of Highway Engineering
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• v.14 no.2
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• pp.55-61
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• 2012

Road signs are important facilities in terms of providing information to driver, they are helpful for driver's judgment as deliver it's own information. However if there is occurrence dew on the road sign because of the change of temperature and humidity, it can be cause of accidents. Therefore it is necessary to develop anti-dew or dew resistance technology. In this research the anti-dew technologies such as insulation road sign and anti-dew film were compared with normal road sign, and the effectiveness analysis was conducted for each alternatives. The quantity of dew on the road sign was check using ANOVA and Tukey HSD and the relation between the retro-reflectivity and quantity of dew on the sign was check using Pearson correlation coefficient. As a result, the sample of anti-dew film attached road sign showed lesser quantity of dew compared with normal road sign. After 90 seconds, the difference of dew quantity for anti-dew film and insulation road sign showed statistically significant result. The relation of between quantity of dew and retro-reflectivity was inverse correlation. As a result, when analyzed the quantity of dew and retro-reflectivity a point of view anti-dew effectiveness, the anti-dew film and insulation road sign showed meaningful result.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.11 no.5
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• pp.588-597
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• 1999

Sokkuram grotto, a UNESCO cultural heritage in Kyongju Korea, was originally covered with crushed rocks over its dome with ventilating holes. The grotto was perfectly preserved for more than 12 centuries until the upper structure was replaced with a concrete dome in the early 20th century to protect from total collapse. Since then, heavy dew formed on the granite surface to seriously damage the sculptures until it was further remodeled with air-conditioning facilities in the 60s. It is considered that the original upper porous structure had a dehumidifying capability. This research is made to unveil the dehumidifying mechanism of the rock layer during the rainy season in that area. A rock layer and a concrete layer are tested in a temperature/humidity-controlled room. No dew formation is observed for the two specimen for continued sunny days or continued rainy days. However, heavy dew formed on the concrete surface for a sunny day after long rainy days. It is thought that the sun evaporates water on the ground and dew is formed at the surface as the highly humid air touches the yet cold concrete. On the contrary, no dew formation is observed for the rock layer at any time. Even in the above worst situation, air flows downward through the cool rock layer and moisture is removed before reaching inside. Temperature measurement, flow visualization, observation of dew formation and measurement of air velocity are made to verify the mechanisms.

• Journal of IKEEE
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• v.22 no.3
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• pp.645-650
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• 2018

IT-based automatic controller that control the temperature and humidity to prevent dew condensation of distributing board was designed and implemented in this paper. The dew condensation temperature was deduced from room temperature and humidity of distributing board. Based on the comparisons between the deduced dew condensation temperature and the temperature of surface condensation, the facilities that can prevent the condensation was implemented to be operated in due order. Also, the remote monitoring module to monitor operation status of controller was implemented using LoRa technique. The performances for controller operation and data transmission were validated from the transmission and operation test for dew condensation prevention. The controller can be put to good use at the facilities that requires the condensation prevention.

• Korean Chemical Engineering Research
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• v.47 no.5
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• pp.565-571
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• 2009

This study was conducted to evaluate hydrocarbon and water dew points of natural gas. For this purpose, algorithm of suppressing divergence was devised to evaluate hydrocarbon dew point up to near critical point and algorithm for finding water dew points lower than that of hydrocarbon, which cannot be calculated by commercial dew point program, was developed. The evaluated values were compared to commercial program and ISO reference values, and the results showed that deviations were zero.

• Journal of Sensor Science and Technology
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• v.26 no.1
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• pp.50-55
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• 2017

The measurement of absolute humidity of gases is essential in many industries. The effect of temperature on aluminum oxide and chilled mirror dew-point hygrometers is investigated. The temperature of laboratory, pipe line, and sensor is varied and the dew point is measured by two different aluminum oxide hygrometers. In all cases, the dew point of hygrometers is increased as the temperature is elevated. The reason behind this observation is due to desorption of water from the inside of pipe line and/or sensor surroundings at elevated temperature that result in the increase of the absolute humidity. Moreover, the sensor itself shows a certain degree of temperature dependency in sensing the humidity especially at low temperature. It is also studied that chilled mirror dew-point hygrometer may indicate a higher dew point than the reference at high temperature because the cooling capability of mirror is decreased at high temperature. Our study will provide evidences in the incorporation of the temperature effect as uncertainty factors in the standard calibration procedure for dew point hygrometers.

• Journal of the Korean Society for Precision Engineering
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• v.28 no.6
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• pp.724-731
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• 2011

Dew generation on an outer surface is considered as an important issue to be settled in the field of home appliances. In the case of a refrigerator that is subject to the dew generation problem on the surface of an outer-door of refrigeration thread, and so as to solve this problem, the electric heater is generally used for drying the dew. However, the heater inevitably requires electrical power consumption that is one of critical issues on the refrigerator. In this study, to prevent dew generation without the heater, a method of using induced heat from room temperature was proposed. In edge sides of a door, high conductive plates are installed and received the heat from outside that is relatively high temperature, and the heat is transferred onto dew generation region. Using prototypes, performance test was conducted under a certain temperature and humidity condition. The experimental results show that the surface temperature on the dew generation region was increased about $0.3{\sim}2.5^{\circ}C$ without use of any heater.

• Korean Journal Plant Pathology
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• v.14 no.6
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• pp.578-582
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• 1998

In greenhouse studies, control efficacy of water chestnut (Eleocharis Kuroguwai) by Epicoccosorus nematosporus was affected by temperature and dew condition. The appressoria were formed abundantly in the range of 20~28$^{\circ}C$. When stem segments o(30 cm long) of the water chestnut were inoculated with the conidial suspension of E. nematorporus, the mean conidial number attacted amounted to 2,545 conidia. Out of 2545 conidia attacted to the stem pieces, 1,733 (68%) conidia formed appressoria. When these stem pieces were treated for 24 hr at 28$^{\circ}C$ under dew condition, 183,1 (7.2%) lesions were formed 10 days after incubation. The time necessary for the death of the plants was about 24 days. Appressoria were formed at 15~35$^{\circ}C$, but decreased rapidly in their numbers at the temperature lower than 1$0^{\circ}C$ or at 35$^{\circ}C$. The appressoria formation seemed to be depended on the dew duration, which was effective to the lesion formation and plant mortality. Under dew duration of 16~24 hr with temperature range of $25^{\circ}C$ to 3$0^{\circ}C$, the weed control was increased up to 93.9%. There were no differences between the first and second or third dew treatments. A delay of 2 or 3 days in dew treatment did not increase the mortality of plants. For the use of E. nematosporus as a mycoherbicide of water chestnut, a conidial suspension should be applied when dew conditions are kept for 12 hr after inoculation.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.7 no.4
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• pp.600-610
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• 1995

When combustion gas is cooled down below the dew point of sulfuric acid vapor in the heat recovery systems, condensation occurs. Since the condensed sulfuric acid solution causes low-temperature corrosion in materials, it is important to measure the SOx dew point by electric measurement. In this study, two kinds of probes having electric gaps of 1mm or 2mm were used. and experiments were carried out by the parameters of sulfuric acid vapor and water vapor concentration. The changes of electric current caused by sulfuric acid condensed on the surface of probe according to the cooling rate and the probe head surface temperature were sudied. The opimum cooling rate was decreased with the increasing of water vaper concentration regardless of sulfuric acid concentration. The sensitivity of electric current is improved for the narrower gap(1mm) of ring electrodes, but it rarely affects the SOx dew point measuring of different probes according to the change of cooling rate.