• Journal of Bio-Environment Control
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• v.8 no.2
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• pp.90-98
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• 1999

This study was conducted to select proper substrate and nutrient solution concentration for favorable growth and quality in common thyme (Thymus vulgaris L.). The growth of common thyme was better in deep flow culture (DFT) than in other substrate cultures. As the nutrient solution concentration rose, the ratio of dry matter increased, while the fresh weight and the number of lateral shoots decreased. The contents of total chlorophyll and vitamin C were higher in DFT than others. Ca, K, P were showed high contents in cocopeat, but Mg content was the highest at half-fold concentration in DFT. Common thyme showed low content of nitrate in DFT compared with that in other substrate culture. DFT was the most effective system for pronoting growth and quality of common thyme. The optimal concentration of nutrient solution in common thyme was half-fold(EC=1.2mS/cm) of herbs nutrient solution by European Vegetable R&D Center.

• Journal of Soil and Groundwater Environment
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• v.16 no.4
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• pp.23-30
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• 2011

Risk based pollution level of Pb and Cd in metal contaminated soils depending on physicochemical properties of soil in a target site was assessed using biotic ligand model. Heavy metal activity in soil solution defined as exposure activity (EA) was assumed to be toxic to Vibrio fischeri and soil organisms. Predicted effective activity (PEA) determined by biotic ligand model was compared to EA value to calculate risk quotient. Field contaminated soils (n = 10) were collected from a formes area and their risk based pollution levels were assessed in the present study using the calculated risk quotient. Concentrations of Pb determined by aqua regia were 295, 258, and 268 mg/kg in B, H and J points and concentrations of Cd were 4.73 and 6.36 mg/kg in G and I points, respectively. These points exceeded the current soil conservation standards. However, risk based pollution levels of the ten points were not able to be calculated because concentrations of Pb and Cd in soil solution were smaller than detection limits or one (i.e., non toxic). It was because heavy metal activity in soil solution was dominant toxicological form to organisms, not a total heavy metal concentration in soil. In addition, heavy metal toxicity was decreased by competition effect of major cations and formation of complex with dissolved organic carbon in soil solution. Therefore, it is essential to consider site-specific factors affecting bioavailability and toxicity for estimating reliable risk of Pb and Cd.

• The Journal of the Korea Contents Association
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• v.14 no.11
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• pp.476-485
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• 2014

This study was to examine the effectiveness of the Solution Focused Group Counseling Program for elementary school students by meta-analysis. For the purpose of the study, master's theses, doctoral dissertations, and journal articles published in Korea up to May, 2014 were systematically reviewed. As a result, a total of 20 studies were eligible for the inclusion criteria. The mean effect sizes and test for homogeneity of effect size (Q-statistic) were analyzed by using Comprehensive Meta-Analysis software 2.0. The main findings of the study were as follows: First, the average effect sizes for Solution Focused Group Counseling Program were ES=1.61 in self-esteem, ES=1.35 in school adjustment capacity, ES=1.07 in interpersonal relationship and ES=1.03 in self-efficacy, Second, the statistically significant moderate variables of the effect size for the Solution Focused Group Counseling Program were 'sessions' of self-esteem and 'sessions', 'running times' in school adjustment capacity. Based on the study results, the research and practice implications were discussed.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.39 no.2
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• pp.177-182
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• 2015

The NOx emissions from diesel engines and industrial boilers are a major cause of environmental pollution. The selective catalytic reduction of urea is an aftertreatment technology that is widely used for the reduction of NOx emissions. The objective of this study was to investigate the characteristics of the thermal decomposition of a urea aqueous solution using laboratory-scale experimental equipment under conditions similar to those of marine diesel engines. A 40 wt. urea aqueous solution was used in this study. It was found that the total conversion rate varied with the inflow gas conditions and flow rates of the urea aqueous solution. In addition, there were conversion rate differences between NH3 and HNCO. At inflow gas temperature conditions of $210^{\circ}C$ and $250^{\circ}C$, the $NH_3$ conversion rate was found to be higher than that of the HNCO, depending on the residence time.

• Environmental Engineering Research
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• v.14 no.1
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• pp.41-47
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• 2009

Column experiments were performed in this study to investigate humic acid adhesion to iron oxide-coated sand (ICS) under different experimental conditions including influent humic acid concentration, flow rate, solution pH, and ionic strength/composition. Breakthrough curves of humic acid were obtained by monitoring effluents, and then column capacity for humic acid adsorption ($C_cap$), total adsorption percent (R), and mass of humic acid adsorbed per unit mass of filter media ($q_a$) were quantified from these curves. Results showed that humic acid adhesion was about seven times higher in ICS than in quartz sand at given experimental conditions. This indicates that humic acid removal can be enhanced through the surface charge modification of quartz sand with iron oxide coating. The adhesion of humic acid in ICS was influenced by influent humic acid concentration. $C_cap$ and $q_a$ increased while R decreased with increasing influent humic acid concentration in ICS column. However, the influence of flow rate was not eminent in our experimental conditions. The humic acid adhesion was enhanced with increasing salt concentration of solution. $C_cap$, $q_a$ and R increased in ICS column with increasing salt concentration. On the adhesion of humic acid, the impact of CaCl2 was greater than that of NaCl. Also, the humic acid adhesion to ICS decreased with increasing solution pH. $C_cap$, $q_a$ and R decreased with increasing solution pH. This study demonstrates that humic acid concentration, salt concentration/composition, and solution pH should be controlled carefully in order to improve the ICS column performance for humic acid removal from water.

• Asian-Australasian Journal of Animal Sciences
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• v.16 no.12
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• pp.1743-1748
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• 2003

The effect of pH on the fermentation characteristics and the formation of cis-9, trans-11 conjugated linoleic acid (CLA) and trans-11 octadecenoic acid by mixed ruminal bacteria was examined in vitro when incubated with linseed or rapeseed. Concentrate (1%, w/v) with ground linseed (0.6%, w/v) or rapeseed (0.5%, w/v) was added to 600 ml mixed solution of strained rumen fluid with artificial saliva (1:1, v/v), and was incubated anaerobically for 12 h at $39^{\circ}C$. The pH of culture solution was maintained at level close to 4.5, 5.3, 6.1 and 6.9 with 30% $H_2SO_4$ or 30% NaOH solution. pH increment resulted in increases of ammonia and total volatile fatty acid (VFA) concentration in culture solutions containing both oilseeds. Fermentation did not proceeded at pH 4.5. Molar proportion of acetate decreased but that of propionate increased as pH increased when incubated with oilseeds. While the hydrogenating process was very slow at the pH range of 4.5 to 5.3, rapid hydrogenation was found from the culture solutions of pH 6.1 and 6.9 when incubated with linseed or rapeseed. As pH in culture solution of linseed or rapeseed increases proportions of oleic acid (cis-9 $C_{18:1}$) and trans-11 octadecenoic acid increased but those of linoleic acid and linolenic acid decreased. The CLA proportion increased with pH in culture solution containing rapeseed but CLA was mostly not detected from the incubation of linseed.

• Journal of the Korean institute of surface engineering
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• v.47 no.4
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• pp.186-191
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• 2014

Double layer films which consisted of aluminum(Al) and magnesium(Mg) have been prepared by e-beam deposition. The structure, alloy phase, and corrosion resistance of the prepared films were investigated before and after heat treatment. The first (bottom) layer fixed with Al, and the thickness ratio between Al and Mg layers has been changed from 1 : 1 to 5 : 1, respectively. Total thickness of Al-Mg film was fixed at $3{\mu}m$. The cold-rolled steel sheet was used as a substrate. Heat treatment was fulfilled in an nitrogen atmosphere at the temperature of $400^{\circ}C$ for 2, 3 and 10 min. Surface morphology of as-deposited Al-Mg film having Mg top layer showed plate-like structure. The morphology was not changed even after heat treatment. However, cross-sectional morphology of Al-Mg films was drastically changed after heat treatment, especially for the samples heat treated for 10 min. The morphology of as-deposited films showed columnar structure, while featureless structure of the films appeared after heat treatment. The x-ray diffraction data for as-deposited Al-Mg films showed only pure Al and Mg peaks. However, Al-Mg alloy peaks such as $Al_3Mg_2$ and $Al_{12}Mg_{17}$ appeared after heat treatment of the films. It is believed that the formation of Al-Mg alloy phase affected the structure change of Al-Mg film. It was found that the corrosion resistance of Al-Mg film was increased after heat treatment.

• Journal of Biosystems Engineering
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• v.32 no.6
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• pp.455-461
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• 2007

The electric current of a flow injection type enzyme-sensor was measured to confirm the stable operating conditions of the sensor. The current of the sensor was decreased as the buffer solution velocity increased. Under the limitation of the cycle time to be below 10 minutes, the effective ranges of the buffer solution velocity were suggested $0.10{\sim}0.26$, $0.12{\sim}0.24$, $0.1{\sim}0.25$ and $0.05{\sim}0.10\;cm/s$ of 1.0, 1.4, 2.4 and 3.4 mm of the electrode diameters, respectively. As the reaction time of the enzyme and the substrate was increased, the current was decreased because of the dilution between the sample and buffer solution. Therefore, it could be recommended that the reaction time was able to be selected as shortly as possible in consideration of the total cycle time. As the result of the experiments using a different volume ratio of the enzyme to substrate, it was concluded that the substrate had to be mixed with the same amount of the enzyme. The current have increased remarkably in proportion to the electrode diameter under 0.1 cm/s of the buffer solution velocity but there was no difference over 0.1 cm/s of the buffer solution velocity. The cross type arrangement of the electrode was highly suggested for application and machining of the sensor.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.43 no.1
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• pp.1-5
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• 1998

Experiments were carried out to find out the optimum water potential, temperature, and duration for the priming of rice seeds, Oryza sativa L. (cv. Ilpumbyeo) for better germination at sub-optimal temperatures. Seeds were primed in 0, -0.2, -0.4, -0.6, -0.8, and -1.0 MPa PEG (polyethylene glycol) solutions at $25^{\circ}C$. The optimum water potential for seed priming, the highest water potential at which rice seeds did not germinate, was -0.6 MPa. To find out optimum priming temperature and duration rice seeds were primed in -0.6 MPa PEG solution and 0 MPa (water as a control) for various durations at 15 and $25^{\circ}C$ and the seeds were germinated at 17, 20, and $25^{\circ}C$. Considering germination rate and speed, the optimum priming time in water (0 MPa) was 4 days at 15$^{\circ}C$ and 1 day at $25^{\circ}C$, while 4 days was the optimum priming time in a -0.6 MPa PEG solution, regardless of the priming temperature. Priming reduced the actual time of germination, especially at sub-optimal temperatures. Priming did not affect germination rate in -0.6 MPa PEG solution at 15$^{\circ}C$, but overpriming reduced the final germination rate in water at 15$^{\circ}C$ and in -0.6 PEG solution at $25^{\circ}C$. Total sugars and $\alpha$-amylase activity induced during the seed priming were negatively correlated with the final germination rate and there was no noted relationship with the speed or uniformity of germination.

• Journal of the Korean institute of surface engineering
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• v.49 no.5
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• pp.454-460
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• 2016

Double-layered Al-Mg films have been deposited by using an e-beam deposition method on a cold-rolled steel sheet(CR), which the structure of the film was Al/Mg/CR. The micro-structure, alloy phase, and corrosion resistance of the Al-Mg coated CR were investigated before and after heat treatment at $400^{\circ}C$ for 2, 3, and 10 min in a nitrogen atmosphere. Total thickness of Al-Mg films was fixed at $3{\mu}m$ and the thickness ratio of Al and Mg layers(Al:Mg) has been changed from 5:1 to 1:5. The cross-sectional morphology of the films, which had the thickness ratio of 2:1(Al:Mg), 1:1, and 1:2, was changed after heat treatment from columnar to featureless structure. The x-ray diffraction data for as-deposited films showed only pure Al and Mg peaks. Al-Mg alloy peaks such as $Al_3Mg_2$ and $Al_{12}Mg_{17}$ phase appeared after the heat treatment. The Al-Mg coating with the thickness ratio of 1:1(Al:Mg) showed the best corrosion resistance of up to 500 hours by salt spray test.