• Journal of Korean Tunnelling and Underground Space Association
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• v.18 no.5
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• pp.401-412
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• 2016

It is extremely difficult to apply conventional grouting methods to subsea tunnelling construction in the high water pressure condition. In such a condition, the rapid artificial freezing method can be an alternative to grouting to form a watertight zone around freezing pipes. For a proper design of the artificial freezing method, the influence of salinity on the freezing process has to be considered. However, there are few domestic tunnel construction that adopted the artificial freezing method, and influential factors on the freezing of the soil are not clearly identified. In this paper, a series of laboratory experiments were performed to identify the physical characteristics of frozen soil. Thermal conductivity of the frozen and unfrozen soil samples was measured through the thermal sensor adopting transient hot-wire method. Moreover, a lab-scale freezing chamber was devised to simulate freezing process of silica sand with consideration of the salinity of pore-water. The temperature in the silica sand sample was measured during the freezing process to evaluate the effect of pore-water salinity on the frozen rate that is one of the key parameters in designing the artificial freezing method in subsea tunnelling. In case of unfrozen soil, the soil samples saturated with fresh water (salinity of 0%) and brine water (salinity of 3.5%) showed a similar value of thermal conductivity. However, the frozen soil sample saturated with brine water led to the thermal conductivity notably higher than that of fresh water, which corresponds to the fact that the freezing rate of brine water was greater than that of fresh water in the freezing chamber test.

• Research in Plant Disease
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• v.16 no.1
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• pp.59-65
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• 2010

This study was conducted to select the cultivars and strains which are suitable in cultivation of the Chinese cabbage having good horticultural characteristics and the resistance to clubroot caused by Plasmodiophora brassicae, which is a widespread disease that causes serious problems in many Brassica growing areas. Thirty four cultivars and nineteen strains of the Chinese cabbage were planted in the contaminated fields in highland and investigated the wilting symptom due to the initial disease occurrence and high temperature. Disease occurrence rate and severity of clubroot and the horticultural characteristics were also examined. According to the results, Bulamplus, Kangryeokyeoleumbaechu among cultivars of Chinese cabbage, SP-05, SP-02, CR DB 50, and CR DB 29 among strains of Chinese cabbage were resistant to hot weather by showing delayed above-ground symptom (wilting) of clubroot in 30 days after transplanting. In case of below-ground clubroot rate, Daetong, super CR Kimi 85 and super CR Hiroki among the cultivars of Chinese cabbage were resistant to clubroot in 60 days after transplanting. When fresh weight of Chinese cabbage among cultivars were compared, super CR Hiroki of over 2,500 g was the highest among other cultivars. Although the resistant and susceptible reactions of Chinese cabbage cultivars and strains against clubroot disease were somewhat different from the above-ground symptoms (wilting) of clubroot in 30 days and below-ground symptoms of clubroot in 60 days, we recommend that super CR Hiroki, CR Kimi 85, CR Janggun among cultivars of Chinese cabbage and CR DB 50 and CR DB 29 among strains of Chinese cabbage will be more suitable in cultivation of Chinese cabbage in highland.

• Journal of Mushroom
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• v.16 no.1
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• pp.22-30
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• 2018

This study was performed to determine optimal extraction conditions of fermented Polygonum multiflorum root by Lentinula edodes (JMI10079) Pegler mycelials using response surface methodology. The independent factors were extraction temperature (X1: $40-100^{\circ}C$), extraction time (X2: 2-10 hrs.), and the ratio of water to sample (X3: 33-100 mg/mL). Their effects were assessed on dependent variables of the extract properties, which included soluble solid contents (Y1), $^{\circ}Brix$ of sample extract (Y2), total polyphenol content (Y3), total flavonoid content (Y4), 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) radical cation scavenging activity (Y5) and 2,2-diphenyl-1-picrylhydrazyl radical scavenging activity (Y6). The experimental data obtained were fit to a second-order polynomial equation. The optimal extraction conditions for fermented P. multiflorum root were: X1: $91.22^{\circ}C$, X2: 7.72 hrs, and X3: 39.71 mg/mL.

• Economic and Environmental Geology
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• v.49 no.5
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• pp.389-410
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• 2016

Wide ranges of fission-track (FT) ages were obtained from the Jurassic granite batholith in Jeonju-Gimje-Jeongeup area, southwestern Okcheon Belt: sphene=158~70 Ma; zircon=127~71 Ma; apatite=72~46 Ma. Thermochronological analyses based on undisturbed primary cooling and reset or partially-reduced FT ages, and some track-length data reveal complicated thermal histories of the granite. The overall cooling of the batholith is characterized by a relatively rapid earlier-cooling (${\sim}20^{\circ}/Ma$) to $300^{\circ}C$ isotherm since its crystallization and a very slow later-cooling ($2.0{\sim}1.5^{\circ}/Ma$) through the $300^{\circ}C-200^{\circ}C-100^{\circ}C$ isotherms to the present surface temperature. It is indicated that the large part of Jurassic granitic body experienced different level of elevated temperatures at least above $170^{\circ}C$ (maximum>$330^{\circ}C$) by a series of igneous activities in late Cretaceous. Consistent FT zircon ages from duplicate measurements for two sites of later igneous bodies define their formation ages: e.g., quartz porphyry=$73{\pm}3Ma$; diorite=$73{\pm}2Ma$; rhyolite=$72{\pm}3Ma$; feldspar porphyry=$78{\pm}4Ma$ (total weighted average=$73{\pm}3Ma$). Intrusions of these later igneous bodies and pegmatitic dyke swarms might play important roles in later thermal rise over the study area including hot-spring districts (e.g., Hwasim, Jukrim, Mogyokri, Hoebong etc.). On the basis of an assumption that the latercooling of granite batholith was essentially controlled by the denudation of overlying crust, the uplift since early Cretaceous was very slow with a mean rate of ~0.05 mm/year (i.e., ~50 m/Ma). Estimates of total uplifts since 100 Ma, 70 Ma and 40 Ma to present-day are ~5 km, ~3.5 km and ~2 km, respectively. The consistent values of total uplifts from different locations may suggest a regional plateau uplift with a uniform rate over the whole granitic body.

• Journal of the Korea Organic Resources Recycling Association
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• v.9 no.1
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• pp.56-64
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• 2001

Composting of livestock feces is economic and safe process to decrease the possibility of direct leakage of organic pollutants to ecosystem from commercial and environmental point of view. This study was conducted with three different experiments related to composting of livestock feces. The purpose of experiment 1 was to investigate changes of characteristic of compost pile during composting period by low temperature in cold season. To compare composting effect of experimental compost pile and control pile exposed in cold air, experimental compost piles were warmed up by hot air until their temperatures were reached at $35^{\circ}C$. Sawdust, Ricehull and Ricestraw were mixed with livestock feces as bulking agent. The highest temperatures of compost pile during composting period were in sawdust, rice hull, rice straw, and control were $75^{\circ}C$, $76^{\circ}C$, $68^{\circ}C$, $45^{\circ}C$ respectively. Moisture content, pH, C/N and volume of compost were decreased during composting period. Experiment 2 was carried out to study utilization effect of compost by plant. A corn was cultivated for 3 years on fertilized land with compost and chemical fertilizer. The amount of harvest and nutrition value of corn were analyzed. In first year of trial, the amount of harvest of corn on land treated with compost was lower by 20% than that of land treated with chemical fertilizer. In second year, there was no difference in yield of com between compost and chemical fertilizer. In third year, the yield of com on land fertilized with compost was much more than that of land fertilized with chemical fertilizer. The purpose of experiment 3 was to estimate the decrease of malodorous gas originating from livestock feces by bio-filter. Four types of bio-filters filled with saw dust, night soil, fermented compost and leaf mold were manufactured and tested. Each bio-filter achieved 87-95% $NH_3$ removal efficiency. This performance was maintained for 10 days. The highest $NH_3$ removal efficiency was achieved by leaf mold on the first day of operation period. It reduced the concentration of $NH_3$ by about 95%. Night soil and fermented compost showed nearly equal performance of 93 to 94% for 10 days from the beginning of operation. The concentration of hydrogen sulfide and methyl mercaptan originating for compost were equal to or less than $3mg/{\ell}$ and $2mg/{\ell}$, respectively. After passing throughout the bio-filter, hydrogen sulfide and methyl mercaptan were not detected.

• Korean Journal of Food Science and Technology
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• v.41 no.3
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• pp.302-306
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• 2009

The principal objective of this investigation was to identify adequate species for the harvest of Perilla frutescens leaves, which provide profound antioxidant activities, and harbor abundant caffeic acid and rosmarinic acid. Namchun, Donggeul-2, Bora, Sae-bora and Neul-bora variants of the plant were assessed herein. In this study, we evaluated the antioxidant effects of these plants, and utilized an HPLC system to verify their caffeic acid and rosmarinic acid contents. Dried Perilla frutescens leaves were boiled at a temperature of $100^{\circ}C$ for three hours, and were lyopholized in a freezedryer. The extracts were then processed in order to confirm their antioxidant activities via 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical-scavenging activity assay, ferric-reducing antioxidant power (FRAP) assay, total flavonoid content and total polyphenol content assays. According to the observed antioxidant results of the five tested species of Perilla frutescens leaves, Bora and Donggeul-2 were shown to have more potent antioxidant activities than the other tested variants. The scavenge 50% of DPPH radical ($SC_50$ of DPPH) values were 241 ${\mu}g$ DM/mL in Donggeul-2 and 261 ${\mu}g$ DM/mL in Bora. Based on the results of the FRAP assay, the Bora variant showed a value of 796 mM $FeSO_4$ $7H_2O/g$ DM, and Donggeul-2 exhibited a value of 748 mM $FeSO_4$ $7H_2O/g$ DM, of which the total polyphenol contents were measured as 69.4 g GAE/kg DM and 61.8 g GAE/kg DM, respectively. Moreover, the Bora variant had the highest level of caffeic acid, and Donggeul-2 showed the highest rosmarinic acid content among the tested samples (0.87 mg/100 g wet base and 121 mg/100 g wet base, respectively). According to the results of this experiment, we selected two species, Bora and Donggeul-2, which were both verified to contain adequate and favorable antioxidant activities.

• Journal of Life Science
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• v.27 no.7
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• pp.754-759
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• 2017

The 100 l culture system was made on the basis of LED light, and Nannochloropsis oculata was cultured in f/2 medium at light intensity ($100{\mu}mol/m^2/s$), culture temperature ($20^{\circ}C{\pm}1^{\circ}C$) and LD cycle (12hr). As a result, the maximum biomass of 1.07 g/l was cultured as a result of 100 l mass culture at $100{\mu}mol/m^2/s$ and 24 mg/l nitrate concentration in LED blue (475 nm). The extraction was carried out using sonicator, homogenizer and chemical method 0.5M HCl shredding method. The contents of chlorophyll a, chlorophyll b and carotenoid were 1.6, 0.5 and 0.3 mg/g cell. When using homogenizer, it was measured at 1.0, 0.6 and 0.2 mg/g cell. The chemical breakdown method of 0.5M HCl, chlorophyll a, b, and carotenoid contents were measured as 0.9, 0.8, 0 mg/g cell. The highest amount of biomass during the distruption time was measured at 3.6 mg/g cell at 15 min disintegration and acetone, 3.6 mg/g cell of acetone, methanol, and ethanol were measured as effective solvents. Concentration was measured by using microfilter, disk type continuous centrifuge and tubular type continuous centrifuge were 16.0, 1.1 and 0.5 g/l, respectively. Four kinds of equipment such as hot air dryer, vacuum dryer, spray dryer and freeze dryer were tested to optimize the drying process. As a result, the recovery rates of spray dryer and freeze dryer were 80% and 60%.

• Food Science and Preservation
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• v.24 no.5
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• pp.565-575
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• 2017

This study was carried out to investigate shelf-life and quality of fresh-cut Dungkunma (Dioscorea bulbifera) in order to elevate utilization of Dungkunma a fresh food. Before vacuum-packaging (in polyethylene/polypropylene film ($100{\mu}m$, $15{\times}20cm$, $75{\pm}2cmHg$) and storaging at $2^{\circ}C$, Dungkunma was peeled out and cut to dice type ($2.0{\pm}0.5cm^3$), and then washed and blanched using hot water (at $90{\pm}2^{\circ}C$ with 2% NaCl solution for 30 sec). Blanched Dungkunma was pre-dried at room temperature, $40^{\circ}C$ and $50^{\circ}C$ for removing surface water. Each peeled dice Dungkunma was packed 50 g in polyethylene/polypropylene film ($100{\mu}m$, $15{\times}20cm$) with vacuum treatment ($75{\pm}2cmHg$) and stored at $2^{\circ}C$ for 90 days. Hardness and adhesiveness of Dungkunma blanched by 2% NaCl and pre-dried at $50^{\circ}C$ (SB50) were the highest, but changes were the least during storage. Lightness and yellowness of stored Dungkunma in all treatments decreased slightly while redness increased during storage. Changes of color of SB50 was the least. Total concentration of aerobic bacteria in SB50 was $1.88{\pm}0.18log\;CFU/g$ during 90 days and E. coli was detected in all treatments during whole storage periods. Dioscin and allantoin contents of SB50 were virtually unchanged during the storage. Consequently, the results of this study suggest that vacuum packaged Dungkunma after blanching using 2% NaCl solution could be effective to prolong the quality of fresh-cut Dungkunma.

• Journal of the Korean Chemical Society
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• v.54 no.5
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• pp.556-566
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• 2010

A new kinetic spectrophotometric method is developed for the measurement of Mn(II) in natural water samples. The method is based on the catalytic effect of Mn(II) with the oxidation of Gallocyanin by $KIO_4$ using nitrilotriacetic acid (NTA) as an activation reagent at 620 nm. The optimum conditions obtained are $4.00{\times}1^{-5}\;M$ Gallocyanin, $KIO_4$, $1.00{\times}10^{-4}\;M$ NTA, 0.1 M HAc/NaAc buffer of pH = 3.50, the reaction time of 5 min and the temperature of $30^{\circ}C$. Under the optimum conditions, the proposed method allows the measurement of Mn(II) in a range of $0.1\;-\;4.0\;ng\;mL^{-1}$ and with a detection limit of down to $0.025\;ng\;mL^{-1}$. The recovery efficiency in measuring the standard Mn(II) solution is in a range of 98.5 - 102%, and the RSD is in a range of 0.76 - 1.25%. The newly developed kinetic method has been successfully applied to the measurement of Mn(II) in both some environmental water samples and certified standard reference river water sample, JAC-0031 with satisfying results. Moreover, few cations and anions interfere with the measurement of Mn(II). Compared with the other catalytic-kinetic methods and instrumental methods, the proposed kinetic method shows fairly good selectivity and sensitivity, low cost, cheapness, low detection limit and rapidity. It can easily and successfully be applied to the real water samples with relatively low salt content and complex matrices such as bottled drinking water, cold and hot spring waters, lake water, river water samples.

• The Korean Journal of Mycology
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• v.34 no.1
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• pp.7-14
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• 2006

Entomopathogenic fungus Cordyceps militaris is famous for its medicinal efficacies. It has been reported to have various pharmacological activities such as anti-tumour, insecticidal, antibacterial, immunomodulatory and antioxidant. In this study, we investigated the effect of the extract of C. militaris (MPUN8501), which was identified by the analysis of the nucleotide sequences of 5.8S ribosomal RNA, on the function of liver. C. militaris powder was extracted using hot water extracts method as time, volume and temperature and using method as differential polarity of organic solvent. Each fraction was tested for the improvement of hepatic enzyme alcohol dehydrogenase (ADH) and acetaldehyde dehydrogenase (ALDH) activity. The BuOH extracts (CME) had highest activity which was used for the test of toxicity and efficacy of C. militaris. The enhancing effect of CME on the activity of ADH and ALDH was much more than medicine, drink, natural tea etc. Thus CME promoted the resolution of alcohol and acetaldehyde in rats, inducing recovery to normal condition rapidly. Furthermore, oral administration of CME effectively protected the carbon tetrachloride-induced acute hepatic injury as revealed by the hematological parameters (levels of sGOT and sGPT) and histological observation. CME was ascertained to be safe by regulatory toxicity studies of single dose toxicity and genotoxicity. These results suggest that CME would be useful for the maintaining normal hepatic activity as a functional health food.