• Advances in environmental research
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• v.7 no.2
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• pp.139-159
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• 2018

Green Leaf Volatiles (GLVs) is a class of biogenically emitted oxygenated hydrocarbons that have been identified as a potential source of Secondary Organic Aerosols (SOA) via aqueous oxidation. The physico-chemical properties of GLVs are vital to understanding their fate and transport in the atmosphere via fog processing, but few experimental data are available. We studied the aqueous solubility, 1-octanol/water partition coefficient, and Henry's law constant ($K_H$) of five GLVs at $25^{\circ}C$: methyl jasmonate, methyl salicylate, 2-methyl-3-buten-2-ol, cis-3-hexen-1-ol, and cis-3-hexenyl acetate. Henry's law constant was also measured at temperatures and ionic strengths typical of fog. Experimental values are compared to scarcely-available literature values, as well as estimations using group and bond contribution methods, property-specific correlations and molecular dynamics simulations. From these values, the partition coefficients to the air-water interface were also calculated. The large Henry's law constant of methyl jasmonate ($8091{\pm}1121M{\cdot}atm^{-1}$) made it the most significant GLV for aqueous phase photochemistry. The HENRYWIN program's bond contribution method from the Estimation Programs Interface Suite (EPI Suite) produced the best estimate of the Henry's constant for GLVs. Estimations of 1-octanol/water partition coefficient and solubility are best when correlating an experimental value of one to find the other. Finally, the scavenging efficiency was calculated for each GLV indicating aqueous phase processing will be most important for methyl jasmonate.

• Journal of Environmental Science International
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• v.21 no.12
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• pp.1511-1521
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• 2012

An attempt is made to analyse characteristic features of heavy rainfalls which occur at the metropolitan area of the Korean peninsular the on- and off- Changma season. For this, two representative heavy rainfall episodes are selected; one is the on-Changma season wherein a torrential rain episode happened at Goyang city on 12 July 2006, and the other is the off-Changma season, a heavy rainfall event in Seoul on 21 September 2006. Both recorded considerable amounts of precipitation, over 250mm in a half-day, which greatly exceeded the amount expected by numerical prediction models at those times, and caused great damage to property and life in the affected area. Similarities in the characteristics of both episodes were shown by; the location of upper-level jet streak and divergence fields of the upper wind over heavy rainfall areas, significantly high equivalent potential temperatures in the low atmospheric layer due to the entrainment of hot and humid air by the low-level jet, and the existence of very dry air and cold air pool in the middle layer of the atmosphere at the peak time of the rainfall events. Among them, differences in dynamic features of the low-level jet and the position of rainfall area along the low-level jet are remarkable.

• Journal of Environmental Science International
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• v.19 no.2
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• pp.217-227
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• 2010

This paper was studied $CO_2$ respiration rate with physicochemical properties of soils at wetland, paddy field and forest in Nongju-ri, Haeryong-myeon, Suncheon city, Jeollanam-do. Soil temperature and $CO_2$ respiration rate were measured at the field, and soil pH, moisture and soil organic carbon were analyzed in laboratory. Field monitoring was conducted at 6 points (W3, W7, W13, W17, W23, W27) for wetland, 3 points (P1, P2, P3) for paddy field and 3 points (F1, F2, F3) for forest in 10 January 2009. $CO_2$ concentrations in chamber were measured 352~382 ppm for wetland, 364~382 ppm for paddy field and 379~390 ppm for forest, and the average values were 370 ppm, 370 ppm and 385 ppm, respectively. $CO_2$ respiration rates of soils were measured $-73{\sim}44\;mg/m^2/hr$ for wetland, $-74{\sim}24\;mg/m^2/hr$ for paddy field and $-55{\sim}106\;mg/m^2/hr$ for forest, and the average values were $-8\;mg/m^2/hr$, $-25\;mg/m^2/hr$ and $38\;mg/m^2/hr$. $CO_2$ was uptake from air to soil in wetland and paddy field, but it was emission from soil to air in forest. $CO_2$ respiration rate function in uptake condition increased exponential and linear as soil temperature and soil organic carbon. But, it in emission condition decreased linear as soil temperature and soil organic carbon. $CO_2$ respiration rate function in wetland decreased linear as soil moisture, but its in paddy and forest increased linear as soil moisture. $CO_2$ respiration rate function in all sites increased linear as soil pH, and increasing rate at forest was highest.

• Economic and Environmental Geology
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• v.39 no.4 s.179
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• pp.495-505
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• 2006

Atmospheric infrasound is defined as low frequency inaudible sound waves generated from natural phenomena and human activities. One property of long-distance travelling of infrasound makes it possible to detect the wave propagated from remote sound sources and to understand many geophysical phenomena generating it. Recently, advanced global infrasound sensor arrays are being deployed to monitor the clandestine nuclear test and to study geophysical phenomena in the world. In Korea, five seismo-acoustic arrays consisting of co-located seismometer and micro-barometer have been operated to discriminate the artificial explosions from the natural earthquakes in and around the Korean Peninsula. In addition to the discrimination purpose, these ways also record distinct infrasonic signals from natural phenomena on global scale such as large earthquake, bolide event, volcanic explosion, typhoon, and so on. As a new frontier in monitoring the earth, infrasound is being applied to understand various phenomena in and above the earth's surface.

• Proceedings of the KSRS Conference
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• 2007.10a
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• pp.49-52
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• 2007

This study uses empirical method to estimate absorption coefficient of colored dissolved organic matter $(a_{dom})$ from GOCI satellite data with the relationship between band ratio of remote sensing reflectance $(R_{rs})$ and $a_{dom}$. For development of $a_{dom}$ estimation algorithm, the used data is in-situ data about ocean optical properties in the around seawater area of the Korean Peninsula during 1998 - 2005. The relationship of $R_{rs}$(412)/$R_{rs}$(555), $R_{rs}$(443)/$R_{rs}$(555), $R_{rs}$(490)/$R_{rs}$(555), $R_{rs}$(510)/$R_{rs}$(555) and $a_{dom}$(412) showed $R^2$ values of 0.707, 0.707, 0.597 and 0.552, respectively. The spectrum of $a_{dom}({\lambda})$ is shape of exponential function $a_{dom}({\lambda})$ value decreases with increasing wavelength. For estimation of $a_{dom}$ from satellite data, we developed an algorithm from the relationship of $a_{dom}$(412) and $R_{rs}$(412)/$R_{rs}$(555). This algorithm was employed on SeaWiFS imagery to estimate $R_{rs}$(412) in the South Sea, East Sea, Yellow Sea and northern East China Sea areas. Also, SeaDAS-derived $a_{dg}$(412) from same SeaWiFS imagery, These $a_{dg}$(412) was then compared with in-situ and empirical-algorithm-derived $a_{dom}$(412), but these values were different. We think two points that such different values are caused by discrepancy related to failure of standard atmospheric correction scheme, the other are caused by error related to definition of $a_{dom}$(412) and $a_{dg}$(412).

• 한국신재생에너지학회:학술대회논문집
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• 2009.11a
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• pp.619-619
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• 2009

Recently, silica nanostructures are widely used in various applicationary areas such as chemical sensors, biosensors, nano-fillers, markers, catalysts, and as a substrate for quantum dots etc, because of their excellent physical, chemical and optical properties. Additionally, these days, semiconductor silica and silicon with high purity is a key challenge because of their metallurgical grade silicon (MG-Si) exhibit purity of about 99% produced by an arc discharge method with high cast. Tremendous efforts are being paid towards this direction to reduce the cast of high purity silicon for generation of photovoltaic power as a solar cell. In this direction, which contains a small amount of impurities, which can be further purified by acid leaching process. In this regard, initially the low cast rice-husk was cultivated from local rice field and washed well with high purity distilled water and were treated with acid leaching process (1:10 HCl and $H_2O$) to remove the atmospheric dirt and impurity. The acid treated rice-husk was again washed with distilled water and dried in an oven at $60^{\circ}C$. The dried rice-husk was further annealed at different temperatures (620 and $900^{\circ}C$) for the formation of silica nanospheres. The confirmation of silica was observed by the X-ray diffraction pattern and X-ray photoelectron spectroscopy. The morphology of obtained nanostructures were analyzed via Field-emission scanning electron microscope(FE-SEM) and Transmission electron microscopy(TEM) and it reveals that the size of each nanosphares is about 50-60nm. Using the Inductively coupled plasma mass spectrometry(ICP-MS), Silica was analyzed for the amount of impurities.

• Transactions of the Korean hydrogen and new energy society
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• v.13 no.2
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• pp.110-118
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• 2002

The hydrogen storage vessel having a good heat conductivity along with a simple structure and a low cost for these alloys was designed and manufactured, and then its characteristic properties were studied in this study. The various parts in hydrogen storage vessel consisted of copper pipes and stainless steel of 250 mesh reached the setting temperature after 4~5 minutes, which indicated that storage vessel had a good heat conductivity that was required in application. And also the storage vessel had a good property of hydrogen transport considering that the reaction time between hydrogen and rare-earth metal alloys in storage vessel was found to be within 10 min at $18^{\circ}C$ under 10 atmospheric pressure. It showed that the average capacity of discharged hydrogen volume was found to be $120{\ell}$ for $MmNi_{4.5}Mn_{0.5}$ under discharging conditions of $40^{\circ}C{\sim}80^{\circ}C$ at a constant flow rate of $5{\ell}$/min. It was found that the optimum discharging temperature for obtaining an appropriate pressure of 3atm was determined to be $60^{\circ}C$ for $MmNi_{4.5}Mn_{0.5}$ hydrogen storage alloy.

• Journal of the Korean Society of Propulsion Engineers
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• v.20 no.6
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• pp.76-82
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• 2016

Recently, environmental sustainability of the transitional explosives and propellants is an issue of growing importance in energetic materials. For examples, ammonium perchlorate(AP) as an solid propellants oxidizer could create a poisonous gas and atmospheric pollutions, such as HCl. Among the several oxidizers, hydrazinium nitroformate(HNF) is an effective candidate substance for eco-friendly oxidizer, which has high density, pressure index, and less smog generating property during combustion for the thrust control system. This study was controlled the size distribution and shapes through various conditions. Length and diameter ratio(L/D) of crystals has below 1 : 3, and the particle size was two types of $200{\mu}m$ and $50{\mu}m$.

• Korean Chemical Engineering Research
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• v.51 no.5
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• pp.602-608
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• 2013

Gas hydrate studies are attracting attention of many researchers as an innovative, economic and environmentally friendly technology when it is applied to $CO_2$ capture, transport, and storage. In this study, we investigated whether $CO_2$ hydrate shows the self-preservation effect or not, that is the key property for developing a novel $CO_2$ transport/storage method. Especially the degree of self-preservation effect for $CO_2$ hydrate was studied according to the particle size of $CO_2$ hydrate samples. We prepared three kinds of $CO_2$ hydrate samples varying their particle diameter as millimeter, micron and nano size and measured their change of weight at $-15{\sim}-30^{\circ}C$ under atmospheric pressure during 3 weeks. According to our experimental result, the lower temperature, larger particle size, and compact structure for higher density are the better conditions for obtaining self-preservation effect.

• Fire Science and Engineering
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• v.31 no.4
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• pp.1-6
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• 2017

A fire resistance certification needs to be obtained before fire protection paint can be used in Korea. In the case of paint, the tests for certification are fire, gas hazard and bond strength. According to the hazard test standard of combustion gas, 16 mice are sacrificed every test. Therefore, there are ethical problems for the experimenter and legal problems for the laboratory. Accordingly, many alternatives are being assessed, such as combustion gas analysis, but they have not replaced animal testing yet. With gas hazard testing, the exhaust gas temperature can be measured. The property of the initial reaction of a specific fire paint can be characterized by this temperature. The purpose of this study was to consider the improvement point for a gas hazard test through comparative analysis of the exhaust temperature and the time of death of the mice.