• Journal of Auto-vehicle Safety Association
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• v.13 no.2
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• pp.30-34
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• 2021

Electrical failures and reliability problems of electronic components by ionic migration between adjacent device terminals have become an issue in automotive electronics. Especially unlike galvanic corrosion, ionic migration is occurred at high temperature and high humidity under applied electric field condition. Until now, although extensive studies of the ionic migrations dealing with PCBs, electrodes, and solders were reported, there is no study on the effect of insulation polymers and metallic fillers for ionic migration. In this research, therefore, ionic migration induced by the types and contents of polymers and metallic fillers, and variety conditions of temperature, humidity, and applied voltage was studied in detail. Ester and amide types of liquid crystal polymer (LCP) and poly (phthalamide) (PPA) were used as base polymers, respectively and compounded with the metallic fillers of Copper iodide (CuI), Zinc stearate (Zn-st), or Calcium stearate (Ca-st) in various compositions. The compounding polymers were fabricated in IPC-B-24 of SIR test coupon according to ISO 9455-17 with Cu electrodes for ionic migration test. While there is no change in LCP-based samples, ionic migration in PPA compounding sample with a high water absorption property was accelerated in the presence of 0.25 wt% or above of CuI at the environmental conditions of 85℃, 85% RH and 48V. The dendritic short-circuit growth of Cu caused by ionic migration between the electrodes on the surface of compounded polymers was systematically observed and analyzed by using optical microscopy and SEM (EDX).

• Journal of the Korean Society of Environmental Restoration Technology
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• v.6 no.3
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• pp.1-8
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• 2003

This study was carried out in order to investigate of effects of environmental conditions which influence negative ions development. Negative ions are nature' most powerful air-cleaning agents, are created by nature, and found at their most optimal levels where the air is most pure and healthy. Negative ions are regarded as one of the important factors which indicate the quality of the air. Therefore, the focus of this study was to clear relationship among negative ions development induced by plant cultivar and environmental conditions such as air temperature, light intensity and relative humidity. As the results of this study, it was found that negative ions development was promoted during the period with plants compared to the period without plants. In Particular, negative ions development was high under air temperature $20^{\circ}C$, relative humidity 90% and dark condition. Temperature and humidity factors on this experiment was strongly affected on negative ions development, but light intensity had almost slight effect. It was shown that these results can contribute to the application of environmental control techniques to negative ions. Among plant cultivar of Spathiphyllum spp. Mentha spicata, and Cupressu arizonica, Mentha spicata was higher negative ions than the other plants, and also the leaves were higher than the stems and roots. The effect of plants on the perception of the inte끼r air quality may, therefore, be one explanation of this results about negative ions. on the other hand, it seems that a green indoor environment might be an increase in general well-being due to the plants.

• International Journal of Industrial Entomology and Biomaterials
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• v.39 no.2
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• pp.74-81
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• 2019

Freeze-dried 3^rd day of 5^th instar silkworm powder (FDSP) has been produced and consumed as functional food ingredient in Korea. Generally, FDSP is distributed in the dehumidification state. In this study, the effect of humid condition (30%, 50%, 70%, and 90% RH) on the quality characteristics of FDSP was examined. The color of FDSP, greenish yellow, becomes dark with the change of redness and yellowness. When FDSP is exposed for 4 h at 90% RH, the lightness was changed from 56 to 51, redness from -0.8 to 3.7, and yellowness from 26.5 to 21.6. The proximate composition of FDSP was not significantly changed except 90% RH condition. At that condition, moisture content (5.7%) was increased to 26.8% and crude fat (11.3%) decreased to 1.9% (3 wk 90% RH). Mineral content change during storage can be classified to 3 types; sulfur rapidly decreased, potassium mostly stable with some decreased with humidity, and sodium increased with high humid condition. Vitamins were not significantly affected. However, DNJ was abruptly decreased to 0.03 g/100g in humid condition.

• Polymer(Korea)
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• v.31 no.4
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• pp.302-307
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• 2007

The resistive-type humidity sensors were prepared from the copolymers of [2-[(methacryloyloxy)ethyl]dimethyl]propylamonium bromide (MEPAB), [2-[(methacryloyloxy)ethyl]-2-hydroxyethyl]dimethylammonium bromide (MEHDAB), 2- [(methacryloyloxy)ethyl]trimethylammonium chloride (METAC), and n-butyl methylacrylate (MBA). Four component copolymers MEPAB/BMA/MEHDAB/METAC=4/4/1/1, 3/5/1/1, 2/6/1/1, 1/7/1/1 crosslinked with blocked-isocyanate on Ag/Pd electrode/alumina substrate showed a good durability at high humidities. The various electrical properties such as frequency dependency, temperature dependency, hysteresis, response time and water durability were examined. In the case of copolymer composed of MEPAB/BMA/MEHDAB/METAC=2/6/1/1, the resistance varied from $1.4\;M{\Omega}$ to $2.9\;k{\Omega}$ at $25^{\circ}C$ in the range of $30{\sim}90\;%RH$ and this copolymers showed a good linearity and low hysteresis.

• Journal of Environmental Science International
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• v.5 no.4
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• pp.453-462
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• 1996

This study was conducted to evaluate the level of atmospheric heavy metals and the relationship of that concentration with weather conditions. This research monitored the concentration of Total Suspended Particulates (TSP) at every three hours by using High Volume Air Sampler from December 24th, of 1995 to Febuary 20th, 1996 in Kimhae area, which recently became a rapidly growing residential and industrial sitc. The items such as air-temperature, relative humidity, radition, wind speed, and wind direction were monitored by using Atmospheric Weather System at the same time. From the collected TSP, the concentration of heavy metals were analyzed by using the Atomic Absorption Spcetrophotometry. The mean concentration of TSP was 110.4 $\mu\textrm{g}$/$m^3$, and the mean concentration of lead (Pb), copper(Cu), chromium (Cr), manganese (Mn), cadmium (Cd), were 0.837 $\mu\textrm{g}$/$m^3$, 0486 $\mu\textrm{g}$/$m^3$, 0.264$\mu\textrm{g}$/$m^3$). The concentration of Pb and Mn was higher in the moring and that of Cu, Cr and Cd was higher in the afternoon and the evening. Regarding the relationship between the concentration of pollutants and weather condition, the-concentration TSP revealed positive correlation with temperature, humidity, wind speed, but negative correlation with tradition (p<0.01). The concentration of Mn revealed positive correlation with temperature and humidity, but negative correlation with wind speed (p<0.01). And the the concentration of pollutants and weather condition revealed higher correlation within the same time period. In summary, the paralleled mornitoring of air conditions and weather condition should be recommended to. get the correct informations concerning the pollution and to prevent the deterioration of air conditions.

• Atmosphere
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• v.29 no.4
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• pp.439-450
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• 2019

Present weather plays an important role not only for atmospheric sciences but also for public welfare and road safety. While the widely used state-of-the-art visibility and present weather sensor yields present weather, a single type of measurement is far from perfect to replace long history of human-eye based observation. Truly automatic present weather observation enables us to increase spatial resolution by an order of magnitude with existing facilities in Korea. 8 years of human-eyed present weather records in 19 sites over Korea are compared with visibility sensors and auxiliary measurements, such as humidity of AWS. As clear condition agrees with high probability, next best categories follow fog, rain, snow, mist, haze and drizzle in comparison with human-eyed observation. Fog, mist and haze are often confused due to nature of machine sensing visibility. Such ambiguous weather conditions are improved with empirically induced criteria in combination with visibility and humidity. Differences between instrument manufacturers are also found indicating nonstandard present weather decision. Analysis shows manufacturer dependent present weather differences are induced by manufacturer's own algorithms, not by visibility measurement. Accuracies of present weather for haze, mist, and fog are all improved by 61.5%, 44.9%, and 26.9% respectively. The result shows that automatic present weather sensing is feasible for operational purpose with minimal human interactions if appropriate algorithm is applied. Further study is ongoing for impact of different sensing types between manufacturers for both visibility and present weather data.

• Journal of Korean Society for Atmospheric Environment
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• v.32 no.5
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• pp.513-525
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• 2016

To propose an effective ensemble methods in predicting $PM_{10}$ concentration, six experiments were designed by different ensemble average methods (e.g., non-weighted, single weighted, and cluster weighted methods). The single weighted method was calculated the weighted value using both multiple regression analysis and singular value decomposition and the cluster weighted method was estimated the weighted value based on temperature, relative humidity, and wind component using multiple regression analysis. The effects of ensemble average methods were significantly better in weighted average than non-weight. The results of ensemble experiments using weighted average methods were distinguished according to methods calculating the weighted value. The single weighted average method using multiple regression analysis showed the highest accuracy for hourly $PM_{10}$ concentration, and the cluster weighted average method based on relative humidity showed the highest accuracy for daily mean $PM_{10}$ concentration. However, the result of ensemble spread analysis showed better reliability in the single weighted average method than the cluster weighted average method based on relative humidity. Thus, the single weighted average method was the most effective method in this study case.

• Korean Journal of Materials Research
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• v.2 no.3
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• pp.163-171
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• 1992

The $SnO_2/TiO_2$ thick film type humidity sensing devices containing 5 to 50 wt% $TiO_2$ have been fabricated by a typical screen printing technique. The surface crystal structure and microstructure were investigated by XRD, SEM and FTIR analyses. And the measurement of sensing characteristics of the thick film devices have been carried out. The crystalline phase of the thick flus were mainly identified as $(SnO_2){\cdot}6T$ crystal structure with XRD analysis, and the thick films sintered at $1300^{\circ}C$ showed an average particle size of $2.0{\mu}m$. The $SnO_2/TiO_2$ device sintered at $1300^{\circ}C$ containing 10 wt% $TiO_2$ showed high sensitivity to humidity in the range of R.H. 20-90%.

• Carbon letters
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• v.8 no.4
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• pp.280-284
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• 2007

Samples of active carbon of $1150\;m^2/g$ surface area were impregnated with ammoniacal salts of copper, chromium and silver, with and without triethylenediamine. The samples of impregnated carbon were aged at $50^{\circ}C$, with and without 90% RH (relative humidity), for a little more than one year and chemically evaluated periodically. Initially copper (II) and chromium (VI) reduced very fast in the samples in humid atmosphere to the extent of 30% and 60% respectively in four months. These values were found to be unaffected by the presence of triethylenediamine (TEDA) indicating that the chemical did not retard the reduction process of chromium (VI) and copper (II). However, in the absence of humidity the reduction of the impregnants was significantly less (10-12%, w/w) in four months. It was quite evident; therefore, that the moisture was mainly responsible for the reduction of chromium (VI) and copper (II) species in impregnated carbons. The prolonged ageing of the samples with and without triethylenediamme after four months with and without humid atmosphere showed that the extent of reduction of chromium (VI) was very low, i.e. 5-10% and of copper (II) was 2-25%. Silver is not reduced due to carbon, as it remained unchanged in concentration on storage. The impregnated carbon samples (100 g) without triethylenediamine, which were aged at room temperature for 5 years in absence of humidity and unaged when evaluated against cyanogen chloride (CNCl) at a concentration of 4 mg/L and airflow rate of 30 lpm showed a high degree of protection (80- 110 minutes).

• Environmental and Resource Economics Review
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• v.25 no.2
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• pp.277-297
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• 2016

This study is to analyze the effects of changing pattern of climate vaariables on total factor productivity of Korea manufacture industry. Changes in temperature, rainfalls and humidity which are the representative climate variables are used as main factors. Not only average values of the variables but those highest values are used as independent variables in the model, in order to consider the characteristic pattern of recent climate change, the high volatilities. The OLS results are unlike to previous literature that temperature and humidity had no significant impact on manufacturing productivity. An increase in the amount of precipitation was analyzed that impact negatively impacted. The analysis of panel data showed that temperatures and precipitation all that does not significantly affect the manufacturing. While the increase of the average humidity is shown to increase the total productivity of manufacture industry. In Korea, adaptation capability is important in determining the effects of climate change on productivity of manufacture industry.