• Journal of Korean Tunnelling and Underground Space Association
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• v.21 no.1
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• pp.31-48
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• 2019

The artificial ground freezing (AGF) method is a groundwater cutoff and/or ground reinforcement method suitable for constructing underground structures in soft ground and urban areas. The AGF method conducts a freezing process by employing a refrigerant circulating through a set of embedded freezing pipes to form frozen walls serving as excavation supports and/or cutoff walls. However, thermal expansion of the pore water during freezing may cause excessive deformation of the ground. On the other hand, as the frozen soil is thawed after completion of the construction, mechanical characteristics of the thawed soil are changed due to the plastic deformation of the ground and the rearrangement of soil fabric. This paper performed a field experiment to evaluate the freezing rate of marine clay in the application of the AGF method. The field experiment was carried out by circulating liquid nitrogen, which is a cryogenic refrigerant, through one freezing pipe installed at a depth of 3.2 m in the ground. Also, a piezo-cone penetration test (CPTu) and a lateral load test (LLT) were performed on the marine clay before and after application of the AGF method to evaluate a change in strength and stiffness of it, which was induced by freezing-thawing. The experimental results indicate that about 11.9 tons of liquid nitrogen were consumed for 3.5 days to form a cylindrical frozen body with a volume of about $2.12m^3$. In addition, the strength and stiffness of the ground were reduced by 48.5% and 22.7%, respectively, after a freezing-thawing cycle.

• Korean Journal of Agricultural and Forest Meteorology
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• v.24 no.3
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• pp.164-178
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• 2022

Uncertainties in weather forecasts would affect the reliability of yield prediction using crop models. The objective of this study was to compare uncertainty in crop yield prediction caused by the use of the weather forecast data. Daily weather data were produced at 10 km spatial resolution using W eather Research and Forecasting (W RF) model. The nearest neighbor method was used to downscale these data at the resolution of 5 km (W RF5K). Parameter-elevation Regressions on Independent Slopes Model (PRISM) was also applied to the WRF data to produce the weather data at the same resolution. W RF5K and PRISM data were used as inputs to the CROPGRO-SOYBEAN model to predict crop yield. The uncertainties of the gridded data were analyzed using cumulative growing degree days (CGDD) and cumulative solar radiation (CSRAD) during the soybean growing seasons for the crop of interest. The degree of agreement (DOA) statistics including structural similarity index were determined for the crop model outputs. Our results indicated that the DOA statistics for CGDD were correlated with that for the maturity dates predicted using WRF5K and PRISM data. Yield forecasts had small values of the DOA statistics when large spatial disagreement occured between maturity dates predicted using WRF5K and PRISM. These results suggest that the spatial uncertainties in temperature data would affect the reliability of the phenology and, as a result, yield predictions at a greater degree than those in solar radiation data. This merits further studies to assess the uncertainties of crop yield forecasts using a wide range of crop calendars.

• Applied Chemistry for Engineering
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• v.25 no.5
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• pp.481-486
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• 2014

This study was performed to test combustive properties of medium density fibreboard (MDF) plates treated with piperazinomethyl-bis-phosphonic acid (PIPEABP), methylpiperazinomethyl-bis-phosphonic acid (MPIPEABP), and N,N-dimethylethylenediaminomethyl-bis-phosphonic acid (MDEDAP). MDF specimens were painted three times with 15 wt% solution of the alkylenediaminoalkyl-bis-phosphonic acids at room temperature. After drying specimen treated with chemicals, combustive properties were examined using the cone calorimeter (ISO 5660-1). As a result, combustion-retardation properties increased due to the treatment of bare MDF with alkylenediaminoalkyl-bis-phosphonic acid solution. Especially, the specimens treated with chemicals showed the ignition (TTI) (148 s~116 s) was retarded and the flameout (Tf) (633 s~529 s) time increased, while the total heat release rate (THRR) (61.1~67.0) $MJ/m^2$ was lowered than those of using virgin plate by reducing the burnig rate. Compared with virgin MDF plate, the specimens treated with the alkylenediaminoalkyl-bis-phosphonic acids showed low combustive properties. However the specimens treated with bis-(dimethylaminomethyl) phosphinic acid (DMDP) showed the higher peak heat release rate (PHRR) ($185.08kW/m^2$) than that of the virgin plate.

• Journal of the Korean Geotechnical Society
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• v.29 no.4
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• pp.23-32
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• 2013

In order to evaluate the bearing capacity behaviour of a monopod suction bucket foundation for an offshore wind tower at the western sea of Korea, a centrifuge load test and numerical analyses were performed. The monopod bucket foundation was designed to be installed in a silty sand layer. The model soil was prepared to simulate a target site by using soil samples having similar properties and controlling relative density. In-flight miniature cone penetration test and bender element array were used to confirm that the model soil had represented the target site conditions. The load - rotation curve of the centrifuge load test was analysed. A series of numerical analyses were performed to validate the experimental conditions. Self-weight of the model, distance to the boundary and elastic modulus of the soil layer were varied to study their effects on the load - rotation curves.

• Fire Science and Engineering
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• v.28 no.3
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• pp.55-61
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• 2014

This study was performed to test the combustive properties of pinus rigida specimens treated with methylpiperazinomethyl-bis-phosphonic acid $M^{n+}$ ($PIPEABPM^{n+}$)s and methylpiperazinomethyl-bis-phosphonic acid (PIPEABP). Pinus rigida Plates were painted in three times with 15 wt% $PIPEABPM^{n+}s$ and PIPEABP solutions at the room temperature respectively. After drying specimen treated with chemicals, combustive properties were examined by the cone calorimeter (ISO 5660-1). It was indicated that the specimens treated with $PIPEABPM^{n+}s$ showed the lower speed to peak mass loss rate ($MLR_{peak}$), (0.104~0.121) g/s than that of PIPEABP plate. In adition, the specimens treated with $PIPEABPM^{n+}s$ showed both the lower total smoke release rate (TSRR), (224.4~484.0) $m^2/m^2$ and $CO_{mean}$ production (0.0537~0.0628) kg/kg than those of PIPEAB plate. Especially, for the specimens treated with $PIPEABPM^{n+}$ by reducing the smoke production rate except 2nd-smoke production rate (2nd-SPR), (0.0254~0.02270) g/s treated with $PIPEABPNi^{2+}$, 2nd-SPR (0.0117~0.0146) g/s was lower than that of PIPEABP plate. Thus, It is supposed that the combustion-retardation properties were improved by the partial due to the treated $PIPEABPM^{n+}s$ in the virgin plate.

• Korean Journal of Microbiology
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• v.49 no.2
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• pp.112-117
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• 2013

Wheat streak mosaic virus (WSMV), a member of the genus Tritimovirus in Potyviridae, severely impacts wheat and corn seed worldwide, but has yet to be detected in Korea, and hence, every effort should be made to prevent its introduction. To prevent WSMV from entering the country, it is necessary to prepare a specific, sensitive, simple, and fast detection method for routine application to plant quarantine procedures. For this reason, a two-step diagnosis system consisting of RT-PCR and nested PCR is being used for WSMV detection. In addition, a novel positive control was developed for use with the system. WSMV has been detected in seed sweet corn from Japan and seed wheat from USA by a two-step diagnosis system, the details of which are described in this study. After sequence analysis, similarities of 80.6 and 100.0% with other isolates were determined by BLAST. They showed the same topology, which was classified as 4 genotypes by various phylogenetic trees, using a poly protein encoding sequence amplification. In this analysis, WSMV-JSweet-corn2868 (JX845574) is classified as clade B, while WSMV-Uwheat1944-1 (KC754959) and WSMV-Uwheat1944-2 (KC754960) belong to clade D.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.37 no.4
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• pp.351-356
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• 2011

Citrus unshiu (C. unshiu) Markovich were dried peel of mandarin orange, of which fresh fruit was one of the famous foods in Korea and Eastern Asia. In the oriental medicine, C. unshiu peel was known to have a diuretic effect and to strengthen spleen function. Recently, natural flavonoids of C. unshiu peel have been investigated. In this study, C. unshiu peel extract containing flavonoid-glycosides was cultured with Schizophyllum commune (S. commune) mycelia producing ${\beta}$-glu- cosidase and its biological activities were investigated. ${\beta}$-glucosidase of S. commune mycelia converted the flavonoid-glycosides (rutin and hesperidin) into aglycones (naringenin and hesperetin). Fermented C. unshiu peel extract compounds were analyzed by HPLC system. The photoprotective potential of fermented C. unshiu peel extract was tested in human dermal fibroblasts (HDFs) exposed to UVA. Fermented C. unshiu peel extract extract also showed notable in vitro anti-inflammatory effect on cellular systems generating cyclooxygenase-2 (COX-2) and 5-lipoxygenase (5-LOX) metabolites. Also, UVB-induced production of interleukin-$1{\alpha}$ in human HaCaT cells was reduced in a dose-dependent manner by treatment with fermented C. unshiu peel extract. These results suggest that fermented C. unshiu peel extract may mitigate the effects of photoaging in skin by reducing UV-induced adverse skin reaction.

• Korean journal of applied entomology
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• v.52 no.4
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• pp.341-348
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• 2013

We desinged and evaluated a remote-sensing sex pheromone trap for real-time monitoring of Mythimna separata (Lepidoptera: Noctuidae), a migratory insect in Korea. The system consisted of a modified cone-trap with a sex pheromone lure, a sensing module based on light interruption, a signal transmission module based on code division multiple access, a main electronic board for system control, a power supply based on a solar collector, a stainless steel-pole supporting the system, and a signal collection and display system based on an internet web page. The ratio (>92%) of the actual number of insects to the signal number in the remote-sensing trap was improved by sensing only within a limited period at night on the basis of the insect's circadian rhythm, control of signal sensitivity on the basis of sensing software programming, 1-h interval for signal transmission, and adjustment of the signal transmission program. The signal occurrence pattern in the remote-sensing trap was conclusively similar (correlation coefficient, >0.98) to the actual pattern of adult occurrence in the trap. The result indicated that the remote-sensing trap based on the attraction of the sex pheromone lure for M. separata has a promising potential for practical use. Occurrence of M. separata adults was observed several times in 2011 and 2012, and the peaks were sharp.

• Applied Chemistry for Engineering
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• v.26 no.4
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• pp.505-510
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• 2015

This study was performed to test the combustive properties of pinus rigida specimens treated with methylpiperazinomethyl-bis-phosphonic acid $M^{n+}$ ($PIPEABPM^{n+}$)s and methylpiperazinomethyl-bis-phosphonic acid (PIPEABP). Each pinus rigida plates were painted three times with 15 wt% $PIPEABPM^{n+}s$ or PIPEABP solutions at the room temperature. After drying specimens treated with chemicals, combustive properties were examined by the cone calorimeter (ISO 5660-1). It was indicated that the speed to peak mass loss rate ($MLR_{peak}$), (0.104~0.121) g/s for specimens treated with $PIPEABPM^{n+}s$ was lower than that of PIPEABP plate. In addition, the total smoke release rate (TSRR), $(224.4{\sim}484.0)m^2/m^2$ for $PIPEABPM^{n+}s$ treated specimens except specimen treated with PIPEABPAl3+ and $CO_{mean}$ production (0.0537~0.0628) kg/kg was smaller than that of PIPEABP plate. In particular, for the specimens treated with $PIPEABPM^{n+}$ by reducing the smoke production rate, the second-smoke production rate (2nd-SPR) $(0.0117{\sim}0.0146)m^2/s$ was lower than that of PIPEABP plate. It can thus be concluded that combustion-retardation properties of the treated $PIPEABPM^{n+}s$ were partially improved compared to those of the virgin plate.

• Journal of the Korean Wood Science and Technology
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• v.44 no.5
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• pp.639-654
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• 2016

This study building materials by relates to human hazard assessment in accordance with the combustion gas SEM, the flame-retardant foam FTIR and cone calorimeter to configure the Forest products of MDF and preservative treated Lauan two kinds of Retardant styrofoam, Styrofoam, Urethane foam and gypsum board four kinds of plastics material by the combustion gas were each analyzed. MDF was burned to the structure of the wood and the glue evenly mixed combustion area preservative treated Lauan, kept constant even in the form of high heat to penetrate deep into the wood flame retardant agents. Retardant styrofoam is due to feed my Dropped dissolved inorganic flame retardant without the fire-stick and confirmed that the weak form of gypsum board, but keep the column. In MDF ammonia ($NH_3$), lethal concentration (750 ppm) compared to 795 ppm, preservative treated Lauan is carbon dioxide ($CO_2$) that was greater than 2.5 times the lethal concentration (100,000 ppm) to 256,965 ppm, the lethal concentration (500 ppm) of hydrogen chloride (HCl). The Urethane greater than 697 ppm, 434 ppm also greatly exceeding the nitrogen dioxide ($NO_2$) lethal concentration (250 ppm) in Retardant styrofoam and 398 ppm was released. It is confirmed that the human body is extremely harmful gas emitted from most of the materials to be utilized as basic data for evaluating the hazard-specific human future building material.