• Journal of Korean Society for Atmospheric Environment
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• v.32 no.3
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• pp.320-328
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• 2016

Among biogenic volatile organic compounds (BVOCs) in the natural ecosystem, monoterpenes, along with isoprene, play important roles in atmospheric chemistry and make significant impacts on air pollution and climate change, especially due to their contribution to secondary organic aerosol production and photochemical ozone formation. It is essential to measure monoterpene concentrations accurately for understanding their oxidation processes, emission processes and estimation, and interactions between biosphere and atmosphere. Thus, traceable calibration standards are crucial for the accurate measurement of monoterpenes at ambient levels. However, there are limited information about developing calibrations standards for monoterpenes in pressured cylinders. This study describes about developing primary standard gas mixtures (PSMs) for monoterpenes at about 2 nmol/mol, near ambient levels. The micro-gravimetric method was applied to prepare monoterpene (${\alpha}$-pinene, 3-carene, R-(+)-limonene, 1,8-cineole) PSMs at $10{\mu}mol/mol$ and then the PSMs were further diluted to 2 nmol/mol level. To select an optimal cylinder for the development of monoterpene PSMs, three different kinds of cylinders were used for the preparation and were evaluated for uncertainty sources including long-term stability. Results showed that aluminum cylinders with a special internal surface treatment (Experis) had little adsorption loss on the cylinder internal surface and good long-term stability compared to two other cylinder types with no treatment and a special treatment (Aculife). Results from uncertainty estimation suggested that monoterpene PSMs can be prepared in pressured cylinders with a special treatment (Experis) at 2 nmol/mol level with an uncertainty of less than 4%.

• Journal of Korean Society for Atmospheric Environment
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• v.30 no.6
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• pp.586-599
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• 2014

During the last two decades, indoor air quality and volatile organic compounds (VOCs) have been of concern in Korean society due to their nature of potential health impacts. In order to investigate the pollution levels of VOCss in indoor environments, establishment of a solid test method for monitoring the airborne VOCss is essential. In Korea, a method based on adsorbent sampling and GC analysis coupled with thermal desorption was proclaimed as the Korea Standard Method for Indoor Air Quality Test. This study was carried out to examine some inherent problems of the VOCs measurement method. The VOCs method does not describe in detail preparing the standard samples. The standard samples may be prepared by impregnation of either liquid standard solutions or a mixture of standard gases. In this study, we investigated the optimal temperature condition for transferring the liquid standards onto a standard adsorbent tube. As a result, keeping the impregnation temperature at $250^{\circ}C$ will be recommended in regard of the boiling points of multiple target analytes and the thermal stability of the adsorbent. We also demonstrated some problems associated with handling of a syringe used for transferring the standard solutions onto the adsorbent tubes, and a best way to get rid of the syringe problems was suggested. Finally, a number of field works were conducted to evaluate the performance of adsorbent sampling methods. Comparison of different adsorbent tubes, i.e. tube packed with single sorbent (Tenax) and double sorbents (Tenax with Carbotrap), revealed that 30 to 40% differences between the two groups, implying that sampling efficiency is depending on the volatility and the strength of adsorbents. However, duplicate precisions for VOCs sampling with a same type of adsorbent and at same flow rates appeared to be satisfactory to be all within 20%, which is a quality control guideline. Distributed volume precisions were also found to be within a guideline value, 25%, although the precision was in general inferior to the duplicate precision. The Korea indoor VOCs test method should be more refined and improved in many aspects, particularly procedure and instrumentation for preparing the standard samples and specification of quality control assessment.

• Korean Journal of Soil Science and Fertilizer
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• v.20 no.1
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• pp.63-67
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• 1987

A laboratory experiment was conducted to find out the concentration of phytotoxin in intensively cultivated hot-pepper, garlic and chinese cabbage, and effects of these phytotoxin to the germination and growth of young hot-pepper plant. Also this experiment presents describes of the bio-assay method and results of phytotoxin application to the toxicity of hot-pepper plant. The results obtained were summarized as follows; 1. A series of non-volatile (aromatic) phenolic compounds such as hydroquinone, benzoic-, p-hydroxybenzoic, and vanillic acid were quantitatively and qualitatively analysed using BSA(N, O-bis(trimethylsilyl)acetamide) by means of gas chromatography method. 2. Phytotoxin as hydroquinone, benzoic-, p-hydroxybenzoic- and vanillic acid were determined in intensively cultivated hot- pepper, garlic and chinese cabbage. Highest concentration of phytotoxin was obtained in hot-pepper cultivated soil. 3. Direct toxic action of the applied phytotoxin to the germination and young hot-pepper plant growth was observed at the levels of 200 ppm. Benzoic acid was obtained the highest toxicity to the young hot-pepper plant growth. 4. Mode of actions of phytotoxins to the young hot-pepper plant growth were observed as stunting of stem elongation, discoloration of leaf and oxygen depletion from consideration as causes of symptom.

• Journal of the Korean Vacuum Society
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• v.16 no.2
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• pp.99-104
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• 2007

Porous silicon exhibiting dual optical properties, both $Febry-P{\acute{e}}rot$ fringe (optical reflectivity) and photoluminescence had been developed and used as chemical sensors. Porous silicon samples were prepared by an electrochemical etch of p-type silicon wafer (boron-doped, <100> orientation, resistivity ; $1-10{\Omega}cm$). Two different types of porous silicon, fresh porous silicon (Si-H terminated) and oxidized porous silicon (Si-OH terminated)by the thermal oxidation, were prepared. Then the samples were exposed to the vapor of various organics, such as methanol, acetone, hexane, and toluene. Both reflectivity and photoluminescence were simultaneously measured under the exposure of organic vapors for sensing VOC's. These surface-modified samples showed unique respond in both reflectivity and photoluminescence with various organic vapors. While polar molecules exhibit greater quenching photoluminescence, molecules having higher vapor pressure show greater red shift for reflectivity.

• Microbiology and Biotechnology Letters
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• v.19 no.2
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• pp.200-207
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• 1991

Jariieot is a local food prepared by fermentation of salted fish, Chromis notatus. Since its NaC' content is around 20% like other fermented seafoods, reduction NaCl concentration is desirable to minimize the risk of health hazard. Addition of KCl and enrichment of lactic acid fermentation were attempted to solve the problems resulting from low salt concentration. NaCl and KCl were added to a fish, Chromis notatus simultaneously at concentrations of 10 to 4% and 5 to 2%, respectively. Lactic acid bacteria and glucose at final concentration of 2% were also mixed with the above-salt treated fish to prepare jarijeot. The jarijeot was examined periodically for chemical changes during aging and compared with reference jarijeot containing only 20% of NaCl to find out an appropriate method for quality improvement. The content of ATP and its related compounds was not affected by the concentration of NaCl or the presence of lactic acid bacteria. Nearly no difference in contents of free amino nitrogen, trimethylamine oxide, trimethylamine and volatile basic nitrogen was observed between the jarijeot containing 20% of NaCl only and that containing 10% of NaCl, 5% of KCl, 2% of glucose and cells of Pediococcus halophilus. Moreover, sensory evaluation of both kinds of jarijeots revealed almost the same scores. The number of cells of P. halophilus was maintained at concentration of $10^5$cell/ml for 60days' fermentation in the above mentioned jarijeot containing 10% of NaCl. Its pH was dropped down to 4.2. Accordingly it is possible to prepare jarijeot enriched with lactic acid bacteria if KCl and glucose are added at concentration of 5% and 2%, respectively, in addition to NaCl at a final concentration of 10%.

• Proceedings of the Korean Environmental Health Society Conference
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• 2005.06a
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• pp.254-258
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• 2005

The purpose of this study is to characterize the indoor-outdoor relationship of airborne pollutants and recognize probable sources in inside and outside individual apartments in Seoul metropolitan. Simultaneous air monitoring in inside and outside of the 16 Korean Apartments classified into 2groups: less than 1 year old and more than 4 years old from October, 2004 to February, 2005were sampled f3r airborne pollutants(volatile organic compounds, formaldehyde, respiratory particles, carbon dioxide and bacteria) using the Korean Indoor Air Quality Official Method. The concentrations of $CO_2$, TVOCs, HCHO, bacteria and PM10 in the less than 1 year old apartments were determined to be $773.6{\pm}422.3ppm$, $4,393.8{\pm}2,758.2{\mu}g/m^3$, $98.0{\pm}56.4{\mu}g/m^3$, $254.0{\pm}186.3CFU/m^3$ and $31.7{\pm}14.8{\mu}g/m^3$, respectively, Also, the concentrations of those in the more than 4 years old apartments were determined to be $798.9{\pm}266.5ppm$, $792.7{\pm}398.3{\mu}g/m^3$, $70.0{\pm}30.7{\mu}g/m^3$, $245.6{\pm}122.0CFU/m^3$, $49.7f28.7{\pm}g/m^3$, respectively. The average ratios of the indoor and outdoor concentrations of $CO_2$, TVOCs, HCHO, bacteria and PM10 were 2.2, 3.6, 3.1, 3.9 and 1.4, respectively. These results of this analysis is suggested that $CO_2$, TVOCs, HCHO, bacteria and PM10 in indoor air are both emitted from source within the apartment environment and partly come from outdoor air. With the above considerations in mind, it is suggested that the research for source contribution of indoor air pollutants should be expanded and the detailed interpretation of the results on these needed further study(using principal component analysis(PCA).

• Journal of Korean Society for Atmospheric Environment
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• v.21 no.2
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• pp.191-204
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• 2005

Building and furnishing materials and consumer product are important sources of volatile organic compounds(VOCs) and other aldehydes in the indoor environment. Some available evidence indicates that VOCs can cause adverse health effects to the building occupants and contribute to some of the symptoms of what we call, 'Sick House Syndrome' in Korea. The aims of this study were to evaluate the efficiency of emission system and to investigate comparison of the emission characteristics of different building materials such as wall-papers, paints, and adhesives. The emission of VOCs from building materials were determined in the small chambers defining the temperature, relative humidity, and ventilation rate in this study. VOCs were sampled for 20 minutes using Tenax-TA tubes and analysed by GC-MS with thermal desorption. The stability of conditions for temperature and relative humidity in this small chamber system showed that the fluctuation of temperature was between 25.4$\pm$0.3$^{\circ}C$ and that of relative humidity was 50.2$\pm$0.6$\%$ under the airflow rate of 167 mL/min. The emission tests from building materials resulted in TVOC emission rates of 0.011 $\~$ 3.108 mg/m$^{2}$h after 7 days. The general wall-papers emitted toluene abundantly and the natural wall-papers mainly emitted n-butanol and a minor amount of alkanes compound such as n -tetradecane. The remainder consisted of toluene, m,p -xylene, and styrene. The paints mainly emitted toluene and the adhesives mainly emitted chloroform as well as toluene. As a result, this study is expected to suggest meaningful data for future studies in exposure control through selecting healthy building materials and for the establishment of guidelines for various building materials in Korea.

• Toxicological Research
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• v.25 no.4
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• pp.209-216
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• 2009

We have recently reported that the continuous exposure of rats to a concrete building environment under cool temperatures had adverse effects on general health parameters and embryo-fetal development. This study examined to compare the potential effects of concrete and wood building environments on pregnant dams and embryo-fetal development in rats. Groups of 10 mated females were exposed to polycarbonate (control), concrete, or wood cages from gestational days (GD) 0 to 20 under cool temperatures $(11.9\sim12.3^{\circ}C)$. All the females underwent a caesarean section on GD 20, and their fetuses were examined for any morphological abnormalities. The temperatures in the cages were similar in all groups but the relative humidity in the concrete and wood groups were higher than in the control group. The concentration of volatile organic compounds in the wood group was higher than in the control group. In the concrete group, maternal effects manifested as an increase in the incidence of clinical signs, a lower body weight, and a decrease in the thymus and ovary weights. Developmental effects included increased post-implantation loss and decreased litter size. Infrared thermal analysis showed that the skin temperature of the rats in the concrete group was lower than that in the control group. In contrast, there were no exposure-related adverse effects on the maternal and developmental parameters in the wood group. Overall, the exposure of pregnant rats to a concrete building environment under cool temperatures has adverse effects on the clinical signs, body weight, skin temperature, organ weight, and embryo-fetal development. On the other hand, exposure to a wood building environment does not have any adverse effects in rats.

• Asian Journal of Atmospheric Environment
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• v.5 no.2
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• pp.121-133
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• 2011

This study suggests criteria to conduct a risk assessment of VOCs and formaldehyde in uncontrolled public facilities. Pollutants and facilities were selected based on two years of monitoring data and exposure scenarios in 573 uncontrolled public facilities, composed of 10 types of public institutions. With the exception of social welfare facilities, lifetime ECRs of formaldehyde and benzene in each facility were higher in employees than in users, except in social welfare facilities. In social welfare facilities, the risk of benzene for users ($1{\times}10^{-5}$) was higher than that of workers ($1{\times}10^{-6}$) because facility users live in the facility 24 hours per day, compared to workers who spend an average of 8 hours per day in the facility. The risk of benzene to workers in restaurants, academies, performance halls, internet cafe and pubs were estimated as high as $1{\times}10^{-4}$ and the risk to workers in the theaters and karaoke bars were recorded as $1{\times}10^{-5}$. Because lifetime ECRs of carcinogens exceeded $1{\times}10^{-4}$ for workers and users in most facilities, risk management of formaldehyde and benzene in these facilities is necessary. Although HQs of toluene and xylenes did not exceed 1.0, their HQs did exceed 0.1 in some facilities, so they were evaluated as potentially harmful materials. Additionally, criteria for health protection in IAQ by facility are suggested at $60-100\;{\mu}g/m^3$ for formaldehyde, $400-500\;{\mu}g/m^3$ for TVOCs, $10-20\;{\mu}g/m^3$ for benzene, $150-170\;{\mu}g/m^3$ for toluene and $100\;{\mu}g/m^3$ for xylenes, based on the survey on IAQ and HRA methodology. The excess rates of IAQ to health protection criteria in all facilities were 16% for formaldehyde, 8% for TVOCs and benzene, 9% for toulene, and 5% for xylenes.

• Journal of Korean Society for Atmospheric Environment
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• v.32 no.5
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• pp.536-546
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• 2016

The diurnal variations of $O_3$ and $NO_2$ in an urban park and the effects of air temperature and wind speed on the diurnal variations are investigated. $O_3$ and $NO_2$ concentrations were observed at a site in an urban park of Seoul from 27 July 2015 to 9 August 2015. The $O_3$ and $NO_2$ concentrations observed in the urban park are compared to those observed at the Gangnam air quality monitoring station (AQMS). The $O_3$ concentration is higher in the urban park than at the Gangnam AQMS in the daytime because the amount of $O_3$ dissociated by NO is smaller as well as partly because the amount of $O_3$ produced in the oxidation process of biogenic volatile organic compounds (VOCs) is larger in the urban park than at the Gangnam AQMS. The $NO_2$ concentration is lower in the urban park than at the Gangnam AQMS during day and night because the observation site in the urban park is relatively far from roads where $NO_x$ is freshly emitted from vehicles. The difference in $NO_2$ concentration is larger in the daytime than in the nighttime. To examine the effects of air temperature and wind speed on the diurnal variations of $O_3$ and $NO_2$, the observed $O_3$ and $NO_2$ concentrations are classified into high or low air temperature and high or low wind speed days. The high $O_3$ and $NO_2$ concentrations in the daytime appear for the high air temperature and low wind speed days. This is because the daytime photochemical processes are favorable when the air temperature is high and the wind speed is low. The scatter plots of the daytime maximum $O_3$ and minimum $NO_2$ concentrations versus the daytime averages of air temperature and wind speed show that the daytime maximum $O_3$ and minimum $NO_2$ concentrations tend to increase as the air temperature increases or the wind speed decreases. The daytime maximum $O_3$ concentration is more sensitive to the changes in air temperature and wind speed in the urban park than at the Gangnam AQMS.