• The Korean Journal of Pesticide Science
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• v.13 no.2
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• pp.79-86
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• 2009

In order to elucidate the residual characteristics of the insecticides, bifenthrin and imidacloprid, the pesticides were sprayed onto the squash and their residues were analyzed with GC-ECD and HPLC. Detection limits of the pesticides were $0.005\;mg;kg^{-1}$ and recoveries of bifenthrin and imidacloprid in squash were from 100.87 to 104.31 and from 79.71 to 92.54%, respectively. Half-lives of bifenthrin and imidacloprid in squash were from 1.8 to 2.9 and from 1.5 to 2.5 days, respectively. Initial concentration of bifenthrin and imidacloprid sprayed at the recommended rate and double rate of recommendation were less than their MRLs. And also, residueal concentrations of the pesticides were rapidly decreased in squash with time. At harvest, estimated daily intakes (EDIs) of the pesticides were less than 0.6% of their acceptable daily intakes (ADIs).

• Tunnel and Underground Space
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• v.24 no.4
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• pp.297-307
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• 2014

Cavern Thermal Energy Storage system stores thermal energy in caverns to recover industrial waste heat or avoid the sporadic characteristics of renewable-energy resources, and its advantages include high injection-and-extraction powers and the flexibility in selecting a storage medium. In the present study, the structural stability of rock mass pillar between these silo-type storage caverns was assessed using a coupled thermal-mechanical model in $FLAC^{3D}$. The results of numerical simulations showed that thermal stresses due to long-term storage depended on pillar width and had significant effect on the pillar stability. A sensitivity analysis of main factors indicated that the influence on the pillar stability increased in the order cavern depth < pillar width < in situ condition. It was suggested that two identical caverns should be separated by at least one diameter of the cavern and small-diameter shaft neighboring the cavern should be separated by more than half of the cavern diameter. Meanwhile, when the line of centers of two caverns was parallel to the direction of maximum horizontal principal stress, the shielding effect of the caverns could minimize an adverse effect caused by a large horizontal stress.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.26 no.3
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• pp.277-285
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• 2016

Objectives: This study was performed in order to evaluate whether 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) could be detected among residents living near Camp Caroll in Waegwan and whether serum concentrations of dioxins, including 2,3,7,8-TCDD, and organochlorine pesticides (OCPs) are associated with length of residence. Methods: Study subjects totaled 113 (for dioxins) and 190 (for OCPs) adults who were selected from participants in a medical investigation. Serum concentrations of dioxins and OCPs were measured using HRGC/HRMS. Information on length of residence was obtained through questionnaires. Results: 2,3,7,8-TCDD was not detected in serum among all subjects. When length of residence was classified as a categorical variable, after adjusting for confounding variables, only residents living in Waegwan for 40 years or longer tended to have high total TEQ values and 2,3,4,7,8-PeCDF with marginal significances. There was no dose-response relation between length of residence and serum concentrations of these chemicals. In multiple regression models with continuous values of the length of residence, total TEQ value and 1,2,3,4,6,7,8-HpCDF were positively associated with length of residence. However, they explained about 3-5% of total variations of serum concentrations of these compounds, while age, consumption of fatty fish, body mass index, alcohol drinking, and cigarette smoking were main variables affecting serum concentrations of dioxins or OCPs. Conclusions: In the current study, high concentrations of certain compounds were mainly observed among persons who lived in Waegwan for at least for 40 years without a dose-response relation. Therefore, it seems difficult to conclude that length of residence meaningfully contributed to the current serum concentrations of dioxins or OCPs among residents in Waegwan. However, considering the half-life of 2,3,7,8-TCDD and indirect exposure routes, the limitations of the current study design should be considered in the interpretation of the study findings.

• Korean Journal of Plant Tissue Culture
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• v.26 no.4
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• pp.275-280
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• 1999

In order to find optimum conditions for somatic embryogenesis from different individual (2-year-old) in Aralia elata were cultured on MS medium supplemented with 1.0 mg/L 2,4-D, 3% sucrose, and 0.3% gelrite. We also investigated the effect of MS medium salt concentration, BA and ABA on the embryo germination and plant regeneration. While noticeable difference was observed on somatic embryo induction among different individual tree, no apparent difference was seen in both germination and regeneration frequencies. Compared with nonembryogenic calli, embryogenic calli tended to look yellow and/or pale brown in color, slowly growing and soft in their texture. Regardless of BA or ABA treatment, half-strength MS salt medium proved to be better than full strength MS medium in both embryo germination and plant regeneration. Both hypocotyl and cotyledon developments were slightly promoted by adding 0.1 mg/L BA. However, its effect on germination and regeneration seemed inferior to control. ABA treatment on somatic embryos at their torpedo and early cotyledonary stages resulted in poor response in germination and regeneration. Although most regenerated plantlets varied greatly in cotyledon number and shape, they could be developed into normal plants after 4 weeks in culture. More than 95% plantlets were acclimatized in an artificial soil mixture, successfully transplanted to nursery bed and grew normally without any phenotypic abnormalty.

• Journal of Life Science
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• v.22 no.8
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• pp.1046-1051
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• 2012

In order to investigate the changes in bioactive materials induced in goldfish brains by $^{18}F$ irradiation, the variations in the neurotransmitter levels in the whole brain were studied. The distance between the goldfish and 580 mCi of $^{18}F$ was about 4 cm, and the exposure lasted for 4 hrs. The absorption level calculated based on the distance, exposure time, and half-life of $^{18}F$ was approximately 2 Gy. After sacrifice by $^{18}F$ irradiation or untreated conditions, ten brains were dissected or immediately frozen, respectively. The tissues were extracted in acetic acid. After lyophilization, the samples were dissolved in distilled water and were further purified on a reverse-phase HPLC column. There were no differences in the intensities of the bioactive materials between $^{18}F$-exposed goldfish and control goldfish, while the only peak corresponded to 13 min, which indicated a significant increase in the irradiated brains. Our analysis has found that this compound is tryptophan. This result suggests that $^{18}F$ leads to changes in a classical neurotransmitter, tryptophan, in both the brains of control goldfish and goldfish contaminated by irradiation.

• Korean Journal of Food Science and Technology
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• v.23 no.2
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• pp.188-191
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• 1991

A study was carried out to investigate the control effect of sodium and potassium phosphates, sodium citrate and three different salts mixtures on kimchi fermentation when they were added into half-fermented kimchi in the concentration range of $0.001{\sim}0.01\;M$. The salts mixtures added were sodium phosphates mixture(CA-A), addition of $NaNO_2$, Ca-EDTA and BHA to CA-A(CA-B) and substitution of BHA with sodium citrate in CA-B. The results showed that sodium phosphates and sodium citrate significantly inhibited the kimchi fermentation while potassium phosphate had little effect. The order of control effect was $Na_3PO_4-Na_2HPO_4-sodium\;citrate-NaH_2PO_4-K_2HPO_4-KH_2PO_4$. Among the salts mixtures, CA-A showed the most reducing effect in the fermentation rate followed by CA-C and CA-A. The mixture of CA-C could extend the time of holding pH $4.2{\sim}4.4$ by approximately 6 times at $4{\sim}25^{\circ}C$ when it was compared to control. The microbial growth study of total and Leuconostoc mesenteroides also showed a very significant decrease in their numbers.

• Applied Biological Chemistry
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• v.12
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• pp.25-31
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• 1969

The characteristics of crude enzyme produced from Trichoderma viride($O_2-1$) which isolated from half spoiled Locust acacia wood (Robinia Pseudacacia Linne) were examined in this paper. The results obtained were summarized as follows: 1) As a results of enzymatic action on several cellulose substrate it was found that there were some sorts of cellulase in crude enzyme. 2) The activity of C.M.C. ase and ${\beta}-glucosidase$ were decreased in accordance with increasing concentration of substrate, and filter paper saccharifying enzyme relatively increased in accordance with increasing concentration of substrate and enzyme in couse of time. 3) The optimal pH of each enzyme was 5.0 and the range of stability on pH generally from 3 to 6. 4) In disintegrating activity on filter paper, in decomposing activity on C.M.C. and $p-nitrophenyl-{\beta}-D-glucoside$, and in saccharifying activity on filter paper, the optimal temperatures were $50^{\circ}C.,\;60^{\circ}C,\;and\;65^{\circ}C$. 5) The order of stability on temperature was as follow; saccharifying activity on filter paper decomposing activity on C.M.C. disintegrating activity on filter paper>decomposing activity on $p-nitrophenyl-{\beta}-D-glucoside$. 6) The activity of the enzymes was inhibited with mercuric and silver ion, and activated with potassium.

• Journal of Soil and Groundwater Environment
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• v.8 no.2
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• pp.55-61
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• 2003

The objective of this study was to investigate the characteristics of nitrate removal by conducting the column test in order to see the performance of surfactant modified zeolite (SMZ) as a permeable reactive barrier material. The prediction of nitrate removal was tested using the one-dimensional advective-dispersive model fitted to the experimental breakthrough curve. A methodology for scaling up to in-situ permeable reactive barrier was also proposed. The breakthrough of nitrate in the column packed with SMZ was well predicted using linear equilibrium adsorption model. The breakthrough time and half-life obtained by breakthrough experiment with variation of flowrates were decreased with the increase of flowrates. When 10㎥/day of groundwater containing the 50 mg/l of nitrate is to be treated to satisfy the potable water quality criteria (10 mg/l) by SMZ reactive barrier, 300 tons of SMZ and about 6 years of breakthrough time will be required, suggesting that 165 million wons are needed as barrier material expenses in each 6 years besides the initial design and construction expenses and the minimal monitoring and maintenance expenses.

• Journal of Plant Biotechnology
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• v.40 no.3
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• pp.147-155
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• 2013

In this experiment, we report for the first time mass propagation by in vitro mircrotuberization of Codonopsis lanceolata. We first examined the effect of cytokinins on multiple shoot induction. 2.0 $mg{\cdot}L^{-1}$ of kinetin not only gave the highest rate of shoot induction (19.1%) but also the elongation of shoot (17.1 mm). Secondly, we investigated the effect of sugars on in vitro microtuberization from nodal segments. The diameter of tuberous roots was enlarged in the half-strength MS medium supplemented with 145.9 mM sucrose. Histological analysis revealed that the number of parenchymatous cell containing starch grains increased in the tuberous roots. In addition, unlike in non-tuberous root, vascular bundles were scattered inner cortex layer. Thirdly, in order to preserve and stimulate the germination, microtubers were stored at $4^{\circ}C$ refrigerator during 9 months and then transplanted to the artificial soils (vermiculrite : peatmoss = 1:1 v/v), resulting that the rates of survival and germination were 75% and 70%, respectively. These results indicated that mass propagation of C. lanceolata was achieved by in vitro microtuber formation, suggesting that this protocol might be applied for not only the propagation of elite clones but also conservation of C. lanceolata germplasm.

• Korean Journal of Organic Agriculture
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• v.25 no.2
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• pp.295-310
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• 2017

This study investigated the growth of five phytopathogenic fungi including Colletotrichum gloeosporioides, Diaporthe citri, Phytophthora capsici and others according to different concentrations of water extract in order to provide reference data for developing environment-friendly agricultural materials using five native Fagaceae species including Quercus acuta, Quercus salicina, Quercus glauca, Quercus gilva and Castanopsis cuspidata var. sieboldii. As the concentration of aqueous extracts of Fagaceae increased according to donor plants, the mycelial growth of phytopathogens showed a decreasing tendency. Differences were found in the degree of inhibition according to types of donor plants and pathogenic fungi. Diaporthe citri, Phytophthora capsici, Pythium graminicola on the water extract of Castanopsis cuspidata var. sieboldii inhibited mycelial growth by 84% in 25% of the treatment group and by 87% in more than half of the treatment group. The water extract of Quercus acuta was found to have no inhibitory effect against the mycelial growth of Diaporthe citri. The aqueous extracts of Quercus salicina, Quercus glauca and Quercus gilva insignificantly inhibited mycelial growth by approximately 15%. The total phenolic content of receptor plants exhibiting antifungal activity was highest in Castanopsis cuspidata var. sieboldii with a content of 22.32 mg/g phenols, followed by Quercus salicina with 8.32 mg/g, Quercus glauca with 6.83 mg/g, Quercus gilva with 5.95 mg/g, and Quercus acuta with 5.24 mg/g. The aqueous extracts of Castanopsis cuspidata var. sieboldii among the five Five Fagaceae Plants of were the most effective antifungal activity.