• Journal of Environmental Health Sciences
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• v.40 no.3
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• pp.204-214
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• 2014

Objectives: Vehicular emissions are one of the main sources of air pollution in urban areas. Correlation analysis was conducted between air pollutants and traffic volume in order to identify causes of air pollution in Gwangju. Methods: Using traffic volumes and air quality monitoring data from 2002 to 2012 from nine stations (seven urban areas, two roadside areas), especially at three sites where traffic volumes were high, the correlation coefficients were obtained between air pollutants as PM-10 (particulate matter), $NO_2$, $SO_2$, CO and $O_3$ at the stations and traffic volumes near the air monitoring stations. Results: Due to traffic volume and distance between the station and the traffic road, concentrations of pollutants at roadside areas were higher than at urban areas, with the exception of $O_3$. The concentration of $O_3$ showed statistically significance with those of other gas materials as $NO_2$, $SO_2$, and CO in winter (p<0.001) and spring (p<0.05). During the period of October 7 to 20, 2012, excluding periods of yellow dust, smog and rainy season, the ratio of $NO/(NO+NO_2)$ showed the highest value 0.57 and 0.40 at Unam and Chipyeong of two roadside stations, followed by 0.35 at Nongseong with vehicular effects. The correlation coefficient between traffic volume and $O_3$, CO, $NO_2$ became higher when the data on mist and haze days were excluded, than when all hourly data were used in that period, at the three sites of Unam, Chipyeong, and Nongseong. Conclusions: Air quality showed a considerable effect from vehicles at roadside areas compared to in urban areas. Air pollutant diminishment strategies need to be aggressively adopted in order to protect atmospheric environment.

• Proceedings of the Korea Air Pollution Research Association Conference
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• 2007.10a
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• pp.106-108
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• 2007

• Korean Journal of Human Ecology
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• v.17 no.5
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• pp.1001-1013
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• 2008

The purpose of this study were to make clear the actual state of indoor air quality by cooling in private institute classrooms and to analyze influencing factors on indoor air quality. The measurements of physical elements and observations of architectural characteristics and living conditions were carried out in each 1 classroom of 5 private institutes. Measuring elements were indoor temperature, relative humidity, $PM_{10}$, HCHO, CO, and $CO_2$ concentration. As results, the averages of indoor temperature each classroom were $21.7\sim28.1^{\circ}C$. 3 classrooms were lower than the Maintenance standard($26\sim28^{\circ}C$) of School Health Law. The means of relative humidity were 48$\sim$63%, all classrooms were ranged within the standard(30$\sim$80%). The means of $PM_{10}$ concentration were 2.1 $\sim$ 17 $\mu g/m^3$, all classrooms were kept within the standard(100 $\mu g/m^3$). The means of HCHO concentration were 0.02$\sim$0.16 ppm, 2 classrooms were exceed the standard(0.1 ppm). The means of CO concentration were 1.4$\sim$3.6 ppm, all classrooms were kept within the standard(10ppm). The means of $CO_2$ concentration were 1,593$\sim$3,819 ppm, all classrooms were exceed the standard(1,000ppm). The results of analysis on influencing factors of the physical elements are as follow; the air conditioner set of temperature, personal necessities like hair spray, teacher's smoking in corridor, windows and doors opening time, the number of students, and volume of classroom.

• Journal of the Korean Society of Safety
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• v.14 no.4
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• pp.60-70
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• 1999

In this study, the computer code for the optimal design of road tunnel ventilation system based on one-dimensional analysis of the air flow was developed. The control volume method was used to calculate the air velocities and the concentration distribution of pollutants(CO, NOx, Particulate) for various tunnel ventilation system. This code was validated by comparing the calculation results to the practical design data for the road tunnel ventilation system. The calculation results were in accord with the practical design data.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.17 no.2
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• pp.125-130
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• 2005

This study was peformed to investigate the phase change temperature, the supercooling, the maintenance time of liquid phase and the change rate of volume of TMA 30 $wt\% clathrate compound with additives. TMA 30 $wt\% clathrate compound with additive was cooled at heat source temperature of $-6^{circ}C$. The additives are ethylene glycol and chloroform. Their concentration are 0.1$wt\% respectively. The experimental results showed that the phase change temperature was not affected by additives and this was average $5.3^{circ}C$. Also the supercooling and the maintenance time of liquid phase were decreased by additives. Especially, the average value of supercooling showed by $8.8^{circ}C$ and the maintenance time of liquid phase was by 19 minutes in the case of chloroform 0.1$wt\%. Additionally, the average change rate of volume showed by $1.26{\~}1.31\%$ according to additives and the volume was decreased by the phase change from liquid to solid.

• Journal of Environmental Health Sciences
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• v.38 no.4
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• pp.360-368
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• 2012

Objective: This study was carried out to use pine needles as a passive air sampler (PAS) of atmospheric Polychlorinated Biphenyls (PCBs). Methods: PCB concentrations in ambient air ($C_a$, ng/$m^3$) and deposited on pine needles ($C_p$, ng/g dry) were analyzed simultaneously from June 1 to December 31. Air samples were taken using a low volume PUF active air sampler and the overall average air volume was about 900-1,000 $m^3$. Pine needles were collected at the end of August and December near the air sampler. Results: $C_a$ were higher at higher air temperature and lower chlorinated PCB congeners, but $C_p$ showed irregular distribution. The average PCB sampling rates from air to pine needles were 0.116 (0.002-0.389) $m^3$/day - g dry. Conclusions: A poor correlation was shown between $C_a$ and $C_p$. However, a good correlation was shown between the logarithm of octanol-air partitioning coefficient ($logK_{oa}$) and log ($C_p/C_a$), and the interrelation was better with longer sampling time (June to December) than shorter sampling time (June to August). The average PCB sampling rates from air to pine needles were the lowest with respect to PUF disk, XAD-2 resin and semipermeable membrane devices (SPMDs) PAS. The average ratio ($C_{a-calc}/C_{a-meas}$) of calculated ($C_{a-calc}$) and measured ($C_{a-meas}$) PCB concentration was 0.69 with a shorter sampling time and 1.24 with a longer, so $C_{a-calc}$ was close to $C_{a-meas}$. It was found that pine needles can be used as PAS of atmospheric PCBs, and are especially suitable for long-time PAS.

• Transactions of the Korean Society of Automotive Engineers
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• v.5 no.3
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• pp.54-65
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• 1997

To quantify the LII signals from soot particle of flames in diesel engine cylinder, a new method has been proposed for correcting LII signal attenuated by soot particles between the measuring point and the detector. It has been verified by an experiment on a laminar jet ethylene-air diffusion flame. Being proportional to the attenuation, the ratio of LII signal at two different detection wavelengths can be used to correct the measured LIIsignal and obtain the unattenuated LII signal, from which the soot volume fraction in the flame can be estimated. Both the 1064-nm and frequency-doubled 532-nm beams from the Nd : YAG laser are used. Single-shot, one-dimensional(1-D) line images are recorded on the intensified CCD camera, with the rectangular-profile laser beam using 1-mm-diameter pinhole. Two broadband optical interference filters having the center wavelengths of 647 nm and 400 nm respectively and a bandwidth of 10 nm are used. This two-wavelength correction has been applied to the ethylene-air coannular laminar diffusion flame, previously studied on soot formation by the laser extinction method in this laboratory. The results by the LII measurement technique and the conventional laser extinction method at the height of 40 nm above the jet exit agreed well with each other except around outside of the peaks of soot concentration, where the soot concentration was relatively high and resulting attenuation of the LII signal was large. The radial profile shape of soot concentration was not changed a lot, but the absolute value of the soot volume fraction around outside edge changed from 4ppm to 6.5 ppm at r=2.8mm after correction. This means that the attenuation of LII signal was approximately 40% at this point, which is higher than the average attenuation rate of this flame, 10~15%.

• Journal of the Korean Institute of Educational Facilities
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• v.25 no.2
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• pp.3-9
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• 2018

This study is designed to measure the indoor environment and research on the environmental situation in the lecture room where the lecture is conducted during the winter time in order to understand the level of environment in the lecture room and then suggest the method of improving the environment in the lecture room in the future. The findings are as follows. First, the number of ventilation measured at Lecture Room 1 was 1.2 times/hour while that at Lecture Room 2 was 2.2 times/hour. Second, the lighting at Lecture Room 1 and 2 was 650~700 lux while the noise at Lecture Room 1 and 2 was not more than 60dB. Third, Group 1 and Group 2 felt in the same way that the air quality in the lecture room was not good when the air quality was measured in 30 minutes after the start of lecture. Fourth, both Group 1 and Group 2 showed the lowered concentration on the class in 30 minutes after the start of the class when the room was heated. But Group 1 got less drop in the concentration when they was put in the non-heated room. Fifth, As for the change in the carbon dioxide volume during lecture, the carbon dioxide volume in the room where the windows was closed rose 1,000~1,400ppm from that at the time of start, thus showing that the indoor air quality got worsened. In addition, it is hard to control the indoor temperature due to the heating and non-heating. Accordingly, it is necessary to get the heating system which can make the ventilation in order to keep the environmental level in the lecture room to a certain level and keep the proper indoor temperature.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.18 no.10
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• pp.826-834
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• 2006

A heat sink system using nanofluidic thermosyphon for electronics systems was studied. The experimental results indicate that a cooling capacity of up to 150 W at an overall temperature difference of $50^{\circ}C$ can be attainable. The heat sink design program also showed that a computer simulation can predict the most of the parameters involved. In the experimental study, the volume concentration of nano particles affect the system performance. Nanofluidic thermosyphon with 0.5% volume concentration showed the best performance. Nanofluid can increase CHF of the system compared with water as a working fluid. The current simulation results were close to the experimental results in acceptable range. The simulation study showed that the design program can be a good tool to predict the effects of various parameters involved in the optimum design of the heat sink.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.12 no.2
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• pp.73-82
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• 2009

The traffic volume of Seoul is extremely high in comparison to other major cities in Korea, and the result has been harmful physical and mental exposure to pollution by Seoulites on a regular basis. The street air pollution is more important than the others, because the air pollution generated by street traffic directly impacts the health of nearby pedestrians. This problem requires urgent attention and resolution. Among the factors creating the air pollution originating from the street, is the configuration of streets, which have emerged as the most significant because it is related to air and pollutant dispersion. Therefore, this study was conducted under the assumption that street form affects the air quality. Study sites were classified by street characteristics, and air quality was analyzed in each class. Then the OSPM (Operational Street Pollution Model) was employed to simulate the relationship between street configuration and air quality of streets within the old city center and new city center in Seoul. After that this study analyzed the correlation between air pollution and the spatial configuration of urban streets (ex. street width, building height, building density, etc.) to determine their contributions to air pollution. The outcome of this study is as follows : First, the result that was derived from the correlation analysis between street configuration and air quality hewed that the air pollution of the street is influenced by the average height of building, width of the roads as well as traffic volume. On the roadside, the concentration level of $NO_2$ is mainly affected by the average height of building and the deviation of building height along the street and CO is affected by street width. The outcome of this study can be used as a basis for more sound urban design policies, and the promotion of desirable street environments for pedestrians.