• Analytical Science and Technology
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• v.13 no.2
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• pp.166-172
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• 2000

The life expectation of power transformers is basically dependent on the aging deterioration of insulating paper which can not be obtained from operating transformers. Therefore, it will be very useful if we can manage transformers by indirect analysis of degradation products. "Furan derivatives" are known the decomposition products which are generated by the degradation of cellulose in insulating paper. We proved that 2-furfural is the only measurable product from our transformers, and determined easily the concentration of 2-furfural by HPLC without any specific pretreatments, Compared to concentration of $CO_2$ and CO by GC, the concentration of 2-furfural by HPLC can estimate more accurately aging characteristics of transformers. We expect that these results can be utilized to predict the aging characteristics and life diagnosis of power transformers.

• Korean Journal of Agricultural and Forest Meteorology
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• v.3 no.2
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• pp.88-95
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• 2001

This study was conducted to investigate vertical movement properties of water quality or chemical composition in three different forest stands (Pinus koraiensis, Larix leptolepis and Quercus spp. stands) in Gwangju-gun and Gyunggi-do. The results were as follows ; The pH range of precipitation was 4.62 ~ 6.72, and the average pH showed 5.74. The relationship of pH among throughfall, stemflow and precipitation showed difference of buffering capacity in tree species. According tree species, acided stemflow and alkalized stemflow had the characteristic value. In three stands, changes of the pH in early rain were larger than those of succeeding rain, except October 1998 and April 1999. Early rain influenced the cation in the acidity and concentration, but succeeding rain influenced the anion such as S $O_{4}$$^{2-}$, N $O_{3}$$^{[-10]}$ , C $l^{[-10]}$ etc. And anion components exist with gas type and minute particles, as a result, succeeding rain influenced to chemical properties by the sustaining washout.

• Korean Chemical Engineering Research
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• v.50 no.1
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• pp.155-161
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• 2012

A dynamic biofilter model was suggested to integrate the effect of biofilter-medium adsorption capacity on the removal efficiency of volatile organic compound (VOC) contained in waste air. In particular, the suggested biofilter model is composed of four components such as biofilm, gas phase, sorption volume and adsorption phase and is capable of predicting the unsteady behavior of biofilter-operation. The process-lumping model previously suggested was limited in the application for the treatment of waste air since it was derived under the assumption that the adsorbed amount of VOC equilibrated with biofilter-media would be proportional to the concentration of dissolved VOC in the sorption volume of biofilter-media. Therefore a Freundlich adsorption isotherm was integrated into a robust biofilter process-lumping model applicable to a wide range of VOC concentration. The values of model parameters related to biofilter-medium adsorption were obtained from the dynamic adsorption column experiments in the preceding article and literature survey. Furthermore a separate biofilter experiment was conducted to treat waste air containing ethanol and the experimental result was compared with the model predictions with various values of Thiele modulus (${\phi}$). The obtained value of Thiele modulus (${\phi}$) was close to 0.03.

• The Journal of Engineering Geology
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• v.21 no.2
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• pp.163-178
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• 2011

A test borehole was drilled in the Cheongwon area to investigate the relationship between geochemical environment and the natural occurrence of radioactive materials (uranium and Rn-222) in borehole groundwater. The borehole encountered mainly biotite schist and biotite granite, with minor porphyritic granite and basic dykes. Six groundwater samples were collected at different depths in the borehole using the double-packed system. The groundwater pH ranges from 5.66 to 8.34, and the chemical type of the groundwater is Ca-$HCO_3$. The contents of uranium and Rn-222 in the groundwater are 0.03-683 ppb and 1,290-7,600 pCi/L, respectively. The contents of uranium and thorium in the rocks within the borehole are 0.51-23.4 ppm and 0.89-62.6 ppm, respectively. Microscope observations of the rock core and analyses by electron probe microanalyzer (EPMA) show that most of the radioactive elements occur in the biotite schist, within accessory minerals such as monazite and limenite in biotite, and in feldspar and quartz. The high uranium content of groundwater at depths of -50 to -70 m is due to groundwater chemistry (weakly alkaline pH, an oxidizing environment, and high concentrations of bicarbonate). The origin of Rn-222 could be determined by analyzing noble gas isotopes (e.g., $^3He/^4He$ and $^4He/^{20}Ne$).

• Korean Journal of Agricultural and Forest Meteorology
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• v.12 no.4
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• pp.307-316
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• 2010

Complex terrain refers to irregular surface properties of the earth that influence gradients in climate, lateral transfer of materials, landscape distribution in soils properties, habitat selection of organisms, and via human preferences, the patterning in development of land use. Complex terrain of mountainous areas represents ca. 20% of the Earth's terrestrial surface; and such regions provide fresh water to at least half of humankind. Most major river systems originate in such terrain, and their resources are often associated with socio-economic competition and political disputes. The goals of the TERRECO-IRTG focus on building a bridge between ecosystem understanding in complex terrain and spatial assessments of ecosystem performance with respect to derived ecosystem services. More specifically, a coordinated assessment framework will be developed from landscape to regional scale applications to quantify trade-offs and will be applied to determine how shifts in climate and land use in complex terrain influence naturally derived ecosystem services. Within the scope of TERRECO, the abiotic and biotic studies of water yield and quality, production and biodiversity, soil processing of materials and trace gas emissions in complex terrain are merged. There is a need to quantitatively understand 1) the ecosystem services derived in regions of complex terrain, 2) the process regulation occurred to maintain those services, and 3) the sensitivities defining thresholds critical in stability of these systems. The TERRECO-IRTG is dedicated to joint study of ecosystems in complex terrain from landscape to regional scales. Our objectives are to reveal the spatial patterns in driving variables of essential ecosystem processes involved in ecosystem services of complex terrain region and hence, to evaluate the resulting ecosystem services, and further to provide new tools for understanding and managing such areas.

• Journal of Korean Society of Environmental Engineers
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• v.28 no.4
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• pp.355-361
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• 2006

In this study, effects of influent C/N(COD/Nitrate) ratio and dissolved oxygen(DO) concentration on biological nitrate removal from groundwater were investigated in the fixed-type biofilter. Influent nitrate of 30 mg/L was removed completely by biological denitrification at the C/N ratio of 10 and 4.0, while residual nitrate of 5 mg/L occurred at the C/N ratio of 2.0, which resulted from deficiency of organic electron donor. Furthermore, nitrite was accumulated up to about 5 mg/L as the C/N ratio decreased to 2.0. Increase in DO concentration also inhibited denitrification activity at the relatively high C/N ratio of 5.0, which decreased the nitrate removal efficiency. Although the influent DO concentration was reduced as low as 0.3 mg/L using sodium sulfite($Na_2SO_3$), effluent nitrite was up to 3.6 mg/L. On the other hand, nitrate was completely removed without detection of nitrite at the DO concentration of 0.3 mg/L using nitrogen gas($N_2$) sparging. The organic matter for denitrification in biofilter were in the range from 3.0 to $3.5gSCOD/g{NO_3}^--N$, while utilized these values increased at the high DO concentration of 5.5 mg/L. In addition to the high DO concentration and the low influent C/N ratio, DO control by chemical such as sodium sulfite affected on biological denitrification, which resulted in the reduction of nitrate removal efficiency and nitrite build-up in a biofilter.

• Journal of Soil and Groundwater Environment
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• v.14 no.4
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• pp.33-44
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• 2009

Water curtain of an underground LPG storage cavern is a facility to prevent leakage of high pressure gases, for which groundwater should flow freely towards the cavern and groundwater level also must be stably maintained. In this study, in order to evaluate qualities of seepage water and surrounding groundwater of an underground LPG storage cavern in Yeosu, 4 rounds of samplings, field measurements and laboratory analyses (February, May, August, October of 2007) were conducted. According to field measurements, pH was weak acidic to neutral but it gradually increased with time. Electrical conductivity (EC) of groundwater near a salt stack showed very high values between 10.47 and 38.50 mS/cm. Dissolved oxygen (DO) showed a very wide range of 0.20~8.74 mg/L and a mean of oxidation-reduction potential (ORP) was 159 mV, which indicated an oxidized condition. Levels of $Fe^{2+}$ and $Mn^{2+}$ were mostly less than 3 mg/L. All of seepage waters showed a Na-Cl type while only groundwater near the salt stack showed a Na-Cl type with a high total dissolved solid. The other groundwaters exhibited typical $Ca-HCO_3$ types. Levels of aerobic bacteria were mostly very high (573-39,520 CFU/mL). Based on the analyses of these hydrochemistry and biological characteristics, it is concluded that there are no particular problems in groundwater and seepage water, which not causing a trouble in the cavern operation. However, both for control of bio-clogging and for sustainable operation of the water curtain system, a regular hydrochemical and microbiological monitoring is required for the seepage water and surrounding groundwater.

• Korean Journal of Mineralogy and Petrology
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• v.35 no.3
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• pp.313-331
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• 2022

Natural or native abiotic molecular hydrogen (H₂) is a major component in natural gas, however yet its importance in the global energy sector's usage as clean and renewable energy is underestimated. Here we review the occurrence and geological settings of native hydrogen to demonstrate the much widesprease H₂ occurrence in nature by comparison with previous estimations. Three main types of source rocks have been identified: (1) ultramafic rocks; (2) cratons comprising iron (Fe²⁺)-rich rocks; and (3) uranium-rich rocks. The rocks are closely associated with Precambrian crystalline basement and serpentinized ultramafic rocks from ophiolite and peridotite either at mid-ocean ridges or within continental margin(Zgonnik, 2020). Inorganic geological processes producing H₂ in the source rocks include (a) the reduction of water during the oxidation of Fe²⁺ in minerals (e.g., olivine), (b) water splitting due to radioactive decay, (c) degassing of magma at low pressure, and (d) the reaction of water with surface radicals during mechanical breaking (e.g., fault) of silicate rocks. Native hydrogen are found as a free gas (51%), fluid inclusions in various rock types (29%), and dissolved gas in underground water (20%) (Zgonnik, 2020). Although research on H₂ has not yet been carried out in Korea, the potential H₂ reservoirs in the Gyeongsang Basin are highly probable based on geological and geochemical characteristics including occurrence of ultramafic rocks, inter-bedded basaltic layers and iron-copper deposits within thick sedimentary basin and igneous activities at an active continental margin during the Permian-Paleogene. The native hydrogen is expected to be clean and renewable energy source in the near future. Therefore it is clear that the origin and exploration of the native hydrogen, not yet been revealed by an integrated studies of rock-fluid interaction studies, are a field of special interest, regardless of the presence of economic native hydrogen reservoirs in Korea.

• Journal of Animal Environmental Science
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• v.18 no.2
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• pp.99-110
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• 2012

The purpose of the study is to collect basis data for to establish standard administrative processes of liquid fertilizer treatment. From this survey we could make out the key point of each step through a case of effective liquid manure treatment system in pig house. It is divided into six step; 1. piggery slurry management step, 2. Solid-liquid separation step, 3. liquid fertilizer treatment (aeration) step, 4. liquid fertilizer treatment (microorganism, recirculation and internal return) step, 5. liquid fertilizer treatment (completion) step, 6. land application step. From now on, standardization process of liquid manure treatment technologies need to be develop based on the six steps process.