• Journal of Korean Society for Atmospheric Environment
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• v.24 no.5
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• pp.613-621
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• 2008

The purpose of this study is to understand the impact that temperature and relative humidity have on the volatilization loss of particulate nitrate $(NO_3^-)$ from Teflon filters during measurements of ambient fine particles $(PM_{2.5})$. Fine particles $(d_p<2.5{\mu}m)$ were measured using an annular denuder system (ADS) at four representive areas in Seoul. The measurements were made during 28 different days at 24-hr sampling intervals from February 14 to October 15, 1997. In this study, nitrate losses. calculated by the ratio of nitrate on the nylon filter to their sum in both Teflon and nylon titters, varied seasonally in the following order: summer (45.5%) > spring (23.8%) > fall (20.6%) > winter (19.7%). The results showed strong correlations with temperature, but we did not observe any significant effects of relative humidity. However, we observed that both temperature and relative humidity influenced the ambient gas/particle nitrate ratio in a different case study using a denuder.

• Journal of Korean Society for Atmospheric Environment
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• v.11 no.4
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• pp.315-321
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• 1995

The purpose of this report is to describe the lidar measurement of depolarization ratios of particulate matter (Depolarization Ratio of Yellow Sand) and to discuss the transformation of aerosols due to Yellow Sand event. The scattering profile shows high level during Yellow Sand event and scattering layers are thicker as compared to other seasons in about 3 .sim. 8km, and the values and mode height of scattering ratio corresponed with depolarization ratio. A distribution of total depolarization ratio during the observation period was 44.7 percent among total cases of 0.03 < Dt < 0.5 with scattering ratio > 30 and relative humidity < 30 was satisfied (popular Yellow Sand type).

• Applied Chemistry for Engineering
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• v.31 no.1
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• pp.57-60
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• 2020

An acetaldehyde, a representative food waste odor, was decomposed using a hybrid system comprised of a non-thermal plasma and catalyst at an ambient temperature under high humidity. A five wt.% Mn was impregnated on two differently structured microporous zeolites, namely Beta and ZSM-5, with a different molar ratio of SiO₂/Al₂O₃. Under high humidity conditions, the acetaldehyde degradation was higher in zeolites with the high ratio of SiO₂/Al₂O₃. Among studied catalysts, a five wt.% Mn/Beta (SiO₂/Al₂O₃ = 300) showed the highest acetaldehyde removal activity owing to its high hydrophobicity and reducibility. During long term stability test using the same catalyst for 110 hours, the acetaldehyde removal activity was relatively well-maintained.

• Journal of Mechanical Science and Technology
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• v.18 no.6
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• pp.1002-1009
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• 2004

Direct contact air conditioning systems, in which heat and mass are transferred directly between air and water droplets, have many advantages over conventional indirect contact systems. The purpose of this research is to investigate the cooling and heating performances of direct contact air conditioning system for various inlet parameters such as air velocity, air temperature, water flow rate and water temperature. The experimental apparatus comprises a wind tunnel, water spray system, scrubber, demister, heater, refrigerator, flow and temperature controller, and data acquisition system. The inlet and outlet conditions of air and water are measured when the air contacts directly with water droplets as a counter flow in the spray section of the wind tunnel, and the heat and mass transfer rates between air and water are calculated. The droplet size of the water sprays is also measured using a Malvern Particle Analyzer. In the cooling conditions, the outlet air temperature and humidity ratio decrease as the water flow rate increases and as the water temperature, air velocity and temperature decrease. On the contrary, the outlet air temperature and humidity ratio increase in the heating conditions as the water flow rate and temperature increase and as the air velocity decreases.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.17 no.10
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• pp.891-897
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• 2005

The characteristics of energy Performance for total heat exchanger have been investigated under various conditions. In cooling operation the latent and enthalpy efficiency are affected by the difference of absolute humidity ratio between indoor and outdoor air. In addition to this the characteristics of absorbing material in the element affects the energy performance. Low dry bulb temperature of indoor air or high absolute humidity ratio in outdoor air give high latent and enthalpy efficiency even with the same temperature difference of dry bulb temperate between indoor and outdoor air.

• Magazine of the Korea Concrete Institute
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• v.8 no.5
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• pp.145-154
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• 1996

Polymer-modified mortars have an excellent water proofness and water retentivity. Therefore, the study on the moisture diffusion behavior- is very important. The purpose of' this study is to investigate the effects of relative humidity and moisture content in mortars on the moisture diffusion, and the relationship between the shrinkage and moisture diffusion coefficient of polymer-modified mortars cured at $20{\circ}C$ 50% R.H and 80% R.H. The pore size distribution of the polymer-modified mortars was also measured. From the test results, the relative humidity and moisture content in mortars influenced on the moisture diffusion of polymer-modified mortars. The shrinkage and moisture diffusion coefficient of polymer-modified mortars cured at $20{\circ}C$ 50% R.H. was bigger than that cured at $20{\circ}C$ 80% R.H.. and decreased with increasing polymer-cement ratio regardless of polymer type.

• Journal of the Korea institute for structural maintenance and inspection
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• v.6 no.1
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• pp.149-158
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• 2002

The carbonation process is affected by both the concrete material properties such as W/C ratio, types of cement and aggregates, admixture characteristics and the environmental factors such as $CO_2$ concentration, temperature, humidity. Based on results of preliminary study on carbonation, this study is to develop a carbonation prediction model by taking account of $CO_2$ concentration, temperature, humidity ad W/C ratio among major factor affecting the carbonation process. And to constitute a model formula which correspond to the mix design of the nuclear power plant, test coefficient that correspond to the design of the nuclear power plant is obtained based on the results of accelerated carbonation test. Also a field coefficient which is obtained based on results of the field examination is included to improve the conformity of the actual structures of nuclear power plant.

• Journal of the Korean Wood Science and Technology
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• v.44 no.2
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• pp.191-203
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• 2016

To investigate the dynamic sorptive and hygroexpansive behaviors of wood by different cyclic hygrothermal changing effects, poplar (populus euramericana Cv.) specimens, were exposed to dynamic sorption processes where relative humidity (RH) and temperature changed simultaneously in sinusoidal waves at 75-45% and $5-35^{\circ}C$ (condition A) and where RH changed sinusoidally at 75-45% but temperature was controlled at $20^{\circ}C$ (condition B), both for three cyclic periods of 1, 6, and 24 h. Moisture and dimensional changes measured during the cycling gave the following results: Moisture and transverse dimensional changes were generally sinusoidal. Moisture and dimensional amplitude increased with increasing cyclic period but all were lower for thicker specimens. The amplitude ratio of condition A to condition B ranged from 1.0 to 1.6 with the maximum value of 1.57 occurring at the shortest cyclic period, not as much as expected. T/R increased as cyclic period increased or specimen thickness decreased. T/R from condition B was weaker than that from condition A. Sorption and swelling hysteresis existed in both conditions. Sorption hysteresis was negatively related to cyclic period but in positive correlation with specimen thickness. Sorption hysteresis was found more obvious in condition B, while moisture sorption coefficient and humidity expansion coefficient showed the opposite results.

• Journal of the Korean Wood Science and Technology
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• v.43 no.5
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• pp.539-547
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• 2015

To investigate dimensional responses of wood under dynamic temperature condition, poplar (populous euramericana Cv.) specimens, 20 mm in radial (R) and tangential (T) directions with two thicknesses of 4 and 10 mm along the grain, were exposed to cyclic temperature changes in square wave between $25^{\circ}C$ and $40^{\circ}C$ at 60% relative humidity (RH) for three different cycling periods of 6 h, 12 h and 24 h. R and T dimensional changes measured during the cycling gave the following results: 1) Transverse dimensional changes of the specimens were generally square but at an opposite phase and lagged behind the imposed temperature changes. The phase lag was inversely correlated with cycling period, but positively related to specimen thickness, while the response amplitude was directly proportional to cycling period, but in a negative correlation with specimen thickness. 2) The specimens showed swelling hysteresis behavior. The heat shrinkage coefficient (HSC) became greater as cycling period increased or specimen thickness decreased. 3) Dimensional changes of the specimens produced deformation accumulation during repeated adsorption and desorption. The deformation accumulating ratio decreased with an increase in cycling period and specimen thickness. 4) Wood suffered 1.5 times as many dimensional changes per unit temperature variation as per unit humidity variation, and this deformation behaved even more seriously under static condition.

• Journal of Environmental Health Sciences
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• v.28 no.2
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• pp.89-98
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• 2002

This study was taken in general hospital, hotel, shopping center, underground cafe, school, house, for the purpose of investigating the distribution of indoor radon concentration in urban area, by E-PERM which approved U.S. EPA, between August and November 1999. There are two sampling Places were exceed 148 ㏃/㎥(4 pCi/L; U.S EPA remedial level), difference mean is 24.0㏃/㎥ when compared with underground vs. aboveground indoor radon concentration in the same building and ratio is 1.6, so underground area is higher than aboveground (p<0.05). Influencing factors were examined. They related to the location of sampler(detector) open or near the door is lower radon concentration than inside portion, which explains probably open area has better ventilated air and dilutes indoor radon concentration. Temperature has a negative relationship (p<0.05) with indoor radon concentration and relative humidity has a positive (p<0.05) Simultaneously to investigate water radon concentration, collected piped-water and the results were very low, which is the same in piped-water concentration other countries. In conclusion, underground indoor radon concentration is higher than aboveground. Concentration was related to sampling spot, open portion is lower than inside. Higher the temperature, lower the indoor radon concentrations. On the other hand higher the relative humidity, higher the indoor radon concentrations. Indoor radon concentration is influenced by sampling point, temperature, relative humidity.