• Economic and Environmental Geology
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• v.35 no.5
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• pp.395-406
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• 2002

The sixty natural springs and community wells used as a drinking water in the Daejeon area are mainly located at the parks and the natural green districts. The purpose of this study is to investigate the characteristics of water quality and the contamination of the springs and the wells, and to suggest the management strategy for the springs and wells. For this study, we undertook water quality data from Daejeon City. According to the statistic analysis of water quality data, unacceptable rate as a drinking water was about 28 percent in 1999 and 24.5 percent in 2000, respectively. Major unacceptable factor is coliform, and others are bacteria, yersinia, color, turbidity, Fe and F. The unacceptable rate shows a roughly positive relationship with precipitation, that is, it shows highest rate during a rainy season between June and September. The major contamination source is likely to be the excrement of wild animals around natural springs and wells. Most of springs are vulnerable to the contamination of coliform and bacteria because of short residence time and shallow circulation in subsurface environment. The water samples collected from 31 springs or wells show weak acidic pHs, the electrical conductivity ranging from 63 to 357 $\mu\textrm{S}$/cm, and the hydrochemical types of Na(Ca)-HC0$_3$ and Ca-HC0$_3$. The groundwater samples of low total dissolved solid(TDS) belong to Na(Ca)-HC0$_3$. type, and the groundwater of high total dissolved solid is shifted towards Ca-HC0$_3$ type in the chemical composition. These hydrochemical characteristics indicate that most natural springs is in the early stage of geochemical evolution. The natural springs should be closed during a rainy season, which shows a high contamination rate. We suggest that a protection barrier around the springs should be built to keep wild animals away from the springs.

• Journal of Korean Society of Forest Science
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• v.77 no.1
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• pp.43-52
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• 1988

One-year-old seedlings of Ginkgo biloba were treated with various simulated acid rains(pH 2.0, pH 3.0, pH 9.0 and pH 5.0) to examine the effects of simulated acid rain on the chemical properties of the tested soil. The seedlings were grown in a pot($4500cm^3$)containing one of three different soils(nursery soil, mixed soil and sandy soil). Simulated acid rain was made by diluting sulfuric and nitric acid solution($H^1SO^4$ : $HNO^3$ =3 : 1, V/V) with tap water and tap water(pH 6.4), and treated by 5mm each time for three minutes during the growing seasons(April to October 1985). Acid rain treatments were done three times per week to potted seedlings by spraying the solutions. The chemical properties of potting media were compared among three soil types as well as among the various pH levels. The results obtained in this study were as follows : 1. Exchangeable calcium and magnesium contents and base saturation of the soil decreased with decreasing pH levels of acid rain, and their decreasing rates were as follows : sandy soil was the highest, followed by mixed and nursery soils, However, exchangeable aluminum content rather increased as the pH levels decreased. 2. Available phosphate in the soil decreased as the pH levels of acid rain decreased. Its content increased in nursery soil, compared with those before acid gain treatment, Gut decreased in mined and sandy soils. 3. Soil sulfate and nitrate contents increased remarkably as the pH levels decreased, and the only significant difference in the sulfate was found among the pH levels. Soil sulfate content was the highest in nursery soil, followed by mixed and sandy soils.

• Journal of Food Hygiene and Safety
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• v.34 no.6
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• pp.551-556
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• 2019

Recently, due to the fact that the mineral content in the wash water of the GAP-certified melon exceeds the GAP wash water standards, there are cases where the certification cannot be maintained. Therefore, agricultural industry demand requesting relaxation of the inorganic elements standard for water quality has been increasing, taking into account the consumption characteristics of Korean melon, which is eaten after removing the peel. This study was conducted to evaluate the human risks of four inorganic materials (fluorine, arsenic, iron and manganese) based on the water quality data of 142 samples of groundwater that was used for washing GAP-certified Korean melon in Seongju area from 2017 to 2019. As a result, the HQ of four minerals in Koreans who consumed groundwater used for washing GAP-certified Korean melons in the Seongju area was below 0.10 on average. In particular, in the case of iron and manganese which are esthetic influence substances, the average HQ was 0.00. The overexposure group showed 0.01, which was lower than the HQ (average 0.01, overexposure group 0.03) of the group that consumed Korean melon. Based on all the results, even if the groundwater of the Seongju area is used to wash GAP-certified Korean melon, the impact from these four inorganic materials, including iron and manganese, for Korean population consuming Korean melon will be minimal.

• Journal of the Korean Institute of Gas
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• v.4 no.1 s.9
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• pp.26-32
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• 2000

The fretting wear corrosion characteristics between the SM20C and the SM20C, the YBsC3 and the STC4H was experimented by using radical type friction experimental device under the corrosion environment of atmosphere, neutral solution, acid solution and chemical factors of the sea water. The affection of underground water that affect fretting wear corrosion of the SM20C which is moving specimen was more sensitive at the STC4H and more insensible at the YBsC3. The affection of underground water that affect fretting wear corrosion of the STC4H was less, but in the $0.5\%\;H_2SO_4$ and $0.5\%\;HNO_3$ solutions the fretting wear corrosion of the STC4H was more large. The fretting wear corrosion of the SM20C which is moving specimen in the underground water was less than in the $3.5\%\;NaCl$, $0.5\%\;H_2SO_4$ and $0.5\%\;HNO_3$ solutions. As time passed, the fretting wear corrosion is increased in the $HNO_3$ solution and dull in the $0.5\%\;H_2SO_4$ solution.

• Journal of Korean Society of Environmental Engineers
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• v.28 no.6
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• pp.620-625
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• 2006

In this investigation, an ICP-DRC/MS method to measure arsenic with ultra-trace concentration without any interference by the compounds such as $^{40}Ar^{35}Cl^+\;and\;^{40}Ca^{35}Cl^+$, which disturb the precise measurement of arsonic was described. Thus, the oxgen was introduced into the dynamic reaction cell as reaction gas and reacted with arsenic ion created in plasma gas, $AsO^+$ was formed and detected with m/z of 91 by ICP-MS. It resulted in better detection limit than the old method with m/z of 75($As^+$). The optimum condition for oxygen supply as the reaction gas was 0.5 mL/min. The analytical features of the method are as follows: detection limit of $0.02{\mu}g/L$, precision(RSD) of 3.4%, and recovery of 96%. Arsenic in the water samples from the tributary streams to the Han River and the main stream of Paldang were analyzed with this method to identify the characteristics in its distribution. The concentration of As ranged from 0.53 to $1.26{\mu}g/L$. We could measure As with very low concentration, less than $1.0{\mu}g/L$, with excellent reproducibility. The method developed is expected to be applied to analyze As of the samples from sea water, food, and domestic and industrial waste water which have high concentration of Cl and/or Ca.

• Korean Journal of Food Science and Technology
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• v.21 no.4
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• pp.575-582
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• 1989

An investigation was carried out to improve the quality and yield of barley tea(water extracts) by modifying the roasting method. The modified methods employed were crushing the barley into 4-10 parts and soaking in water at room temperature for 20 minutes followed by roasting (light brown or dark brown) at $250^{\circ}C$ before boiling with water. The varieties of barley used for this study were Ol-bori(with hulls) and Youngsan-bori(without hulls) and the qualities measured were the physical, chemical and sensory characteristics of roasted barley and its extracts. The results showed that the higher solid yields in barley tea was obtained with an increase in soaking and roasting time. The solid yields increased rapidly with extraction time in boiling water until 30 minutes and then slowed down thereafter. However the intrinsic viscosity of barley tea was reduced by increase in soaking and roasting time. The color of barley tea expressed as Hunter L, a, b values showed that lower L value and higher a and b values were measured for those prepared without soaking and with more extensive roasting. Organoleptic evaluation clearly showed that the sensory quality of barley tea was significantly improved in intensity of odor and taste by crushing, soaking and dark brown roasting.

• Clean Technology
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• v.19 no.4
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• pp.464-468
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• 2013

In this study, in order to increase solid content of coal water fuel (CWF), various experimental parameters (i.e., coal type, additive, particle size distribution, drying method) were evaluated. To investigate the drying method, specimen is compared to using flash dry, fluidized bed dry and oil deposit stabilized coal. Difference of the solid content between low rank coal and high rank coal in this case indicate that high rank coal exhibits more higher than 20% of the solid cotent. And specimen for dispersibility was prepared by using dispersing agent of 4 types. As a result, using the dispersing agent was shown 5% higher in sold content than the case of not using the dispersing agent. Efficiency of CWF was improved by using fine coal of 80% in the particle size distribution of coal. Result of CWF using drying methods of 3 types, oil deposit stabilized (ODS) coal dried and stabilized was effective 12% higher in sold content than raw coal.

• Journal of Korean Society on Water Environment
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• v.28 no.5
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• pp.729-742
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• 2012

Recently, to using chemical coagulation process for T-P removal in STP effluent as tertiary treatment process is generalized in the country. The importance of analysis technique to save the treatment & maintenance cost during coagulation process is becoming more increased each day. Thus, it is necessary for the analysis technique during coagulation process to be presented well the characteristic of coagulation in field apply. There are a few analysis techniques such as Jar Test, zeta potential analysis and streaming current detecting techniques. But there are difficult to apply in field immediately due to long test time and difficult analysis techniques. And using PDA technique, it is reviewed applicability of the techniques as field index on pilot plant of P-CAP system The P-CAP system is composed of an in-line static mixer, a Flocculation Tank and the CAP reactor with 2 stage weir for effluent. Pre-test is performed to fix the mixing velocity in the Flocculation Tank using the PDA equipment and it fixed with 30RPM. Also, Jar Test is performed to select optimum dose of each coagulant for each T-P concentration level of influent. Result of continuous test on pilot plant of P-CAP system, the FSI in the Flocculation Tank is increased consistently by increasing each dosing concentration of coagulant such as LAS and PAC in the low level influent T-P concentration comparatively. It is considered that formed Al-hydroxide complexes for dosed coagulant are caused FSI variation. Furthermore, it seems that FSI value in the high level influent T-P concentration appeared lower than the opposite influent condition relatively because it is formed simultaneously Al-hydroxide complexes as solid type and Al-phosphorus complexes as soluble type. Thus, relation of FSI by PDA technique and T-P removal of final effluent on pilot plant of P-CAP system are very limited for the kind of coagulant and the characteristics of influent. And it though that FSI value by PDA technique with analyzing of turbidity in Flocculation Tank will be used restrictedly on field as the relative field-index.

• Transactions of the Korean hydrogen and new energy society
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• v.26 no.5
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• pp.423-430
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• 2015

$Cu/ZnO/Al_2O_3$ catalysts for water gas shift (WGS) reaction were synthesized by co-precipitation method with the fixed molar ratio of Cu/Zn/Al precursors as 45/45/10. Copper and zinc precursor were added into sodium carbonate solution for precipitation and aged for 24h. During the aging period, aluminum precursor was added into the aging solution with different time gap from the precipitation starting point: 6h, 12h, and 18h. The resulting catalysts were characterized with SEM, XRD, BET surface measurement, $N_2O$ chemisorption, TPR, and $NH_3$-TPD analysis. The catalytic activity tests were carried out at a GHSV of $27,986h^{-1}$ and a temperature range of 200 to $400^{\circ}C$. The catalyst morphology and crystalline structures were not affected by aluminum precursor addition time. The Cu dispersion degree, surface area, and pore diameter depended on the aging time of Cu-Zn precipitate without the presence of $Al_2O_3$ precursor. Also, the interaction between the active substance and $Al_2O_3$ became more stronger as aging duration, with Al precursor presented in the solution, increased. Therefore, it was confirmed that aluminum precursor addition time affected the catalytic characteristics and their catalytic activities.

• Journal of Life Science
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• v.23 no.2
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• pp.249-258
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• 2013

The antioxidative activity and bioactivity of water, ethanol, and methanol extracts from Paecilomyces japonica (PJ), Cordyceps militaris (CM), and cordycepin-enriched C. militaris JLM0636 ($CM{\alpha}$) were tested in in vitro experimental models. The PJ water extract showed the highest extraction yield (42.53%). The highest content of phenolic compounds and flavonoids were found in the water extract of PJ, 2.72% and 1.73%, respectively. The major minerals were K, Mg, and Ca. The water extracts of PJ also showed the highest DPPH free radical scavenging activity and reducing power. Linoleic acid peroxidation and antioxidative activities were strong in $CM{\alpha}$. The methanol extracts of PJ showed the highest inhibition activity against tyrosinase. Fibriolytic activity was higher in $CM{\alpha}$ than in CM. These results may provide basic data to understand the biological activities of bioactive materials derived from $CM{\alpha}$ for the development of functional foods, cosmetics, and antithrombotics.