• Journal of vocational education research
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• v.35 no.6
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• pp.39-63
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• 2016

The purpose of this study was to identify the factors affecting the actual employment rate and job retention rate after completion of the training program the unemployed. Survival analysis was conducted by utilizing employment insurance status and subscription data over two years of 840 patients who finally completed a training course from 889 patients in response to survey about the training service quality in 2012. The finding of the study were as follows. First, the highest employment rate (36.8%) after the completion time was within three months, a period more than 50% of the trainees were employed within six months. While employment continued to occur even with the lapse of one year and two years after the completion point, the employment rate over time was found to decrease gradually. Second, the factors affecting employment rate after completing training, appeared teaching competency(-) among training service quality and potential employability(+), which low awareness of teaching capacity and high awareness potential employability increased the possibility of their employment. Third, the highest periods (each 22.0%, 22.3%) of employment loss rate were within three months and within three to six months, and more than 50% of the trainees have lost their unemployment insurance were less than 8.8 months. Fourth, the factors affecting job retention rates after employment, appeared relationship between teachers and students(+), a fellow student relationships(+) among training service quality and training satisfaction(+), which high awareness of teacher-student relationships, fellow student relationships and training satisfaction increased the possibility of their maintaining employment.

• Journal of Electrochemical Science and Technology
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• v.2 no.3
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• pp.157-162
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• 2011

We report a simple route for synthesizing multi-dimensional structured silicon anode materials from commercially available bulk silicon powders via metal-assisted chemical etching process. In the first step, silver catalyst was deposited onto the surface of bulk silicon via a galvanic displacement reaction. Next, the silver-decorated silicon particles were chemically etched in a mixture of hydrofluoric acid and hydrogen peroxide to make multi-dimensional silicon consisting of one-dimensional silicon nanowires and micro-scale silicon cores. As-synthesized silicon particles were coated with a carbon via thermal decomposition of acetylene gas. The carbon-coated multi-dimensional silicon anodes exhibited excellent electrochemical properties, including a high specific capacity (1800 mAh/g), a stable cycling retention (cycling retention of 89% after 20 cycles), and a high rate capability (71% at 3 C rate, compared to 0.1 C rate). This process is a simple and mass-productive (yield of 40-50%), thus opens up an effective route to make a high-performance silicon anode materials for lithiumion batteries.

• Journal of Wetlands Research
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• v.7 no.3
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• pp.75-85
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• 2005

The Construction of industrial complex areas means the increase of imperviousness rate and the increase of nonpoint pollutant emissions during a rainfall. Generally the retention basin can become the alternative for removing and controling these nonpoint pollutants. Recently Ministry of Environment are trying to change the purpose of retention basins from flooding control to nonpoint pollutant control. In order to propel the stormwater management program, administration plan of stormwater management is enacted in Spring, 2005. Hereafter, in a newly developing area, the best management practices should be established to control the nonpoint pollutant. Landuses of the research area are classified to the categories of the 1st manufacturing industry, metal industry, fiber and chemical product manufacturing industry, etc. Therefore, this research was performed to understand washed-off characteristics of stormwater and to suggest the controling method of nonpoint pollutants. The optimum capacity of the retention basin can be determined by analyzing the relationships among data of rainfall, runoff, washed-off pollutants from the areas. The rainfall analysis using the data of normal year, recent 2, 5 and 10 years shows that the 80% rainfall frequency was occurred on 10mm accumulated rainfall, but which is not considered the first flush effect. However, by considering the first flush effect, the appropriate treatment capacity of rainfall can be decreased to 4-5mm accumulated rainfall. Using the criteria, the optimum capacity of retention basin is determined to $12,000m^3$ in the research area. The washed-off nonpoint pollutant loading from the areas have beeb calculated to 435ton/yr for TSS, 238ton/yr for COD, 8,518kg/yr for TKN and 1,816kg/yr for TP. The mass of 78.3ton/yr for TSS, 20.4ton/yr for BOD, 128.6ton/yr for COD, 4.6ton/yr for TKN and 980kg/yr for TP can be reduced by constructing the retention basin. The sediment accumulation rate is also calculated by $6.53kg/m^2-hr$.

• Journal of Electrochemical Science and Technology
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• v.3 no.3
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• pp.116-122
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• 2012

As an effort to address the chronic capacity fading of Si anodes and thus achieve their robust cycling performance, herein, we develop a unique electrode in which silicon nanoparticles are embedded in the carbon nanotubes network. Utilizing robust contacts between silicon nanoparticles and carbon nanotubes, the composite electrodes exhibit excellent electrochemical performance : 95.5% capacity retention after 140 cycles as well as rate capability such that at the C-rate increase from 0.1C to 1C to 10C, the specific capacities of 850, 698, and 312 mAh/g are obtained, respectively. The present investigation suggests a useful design principle for silicon as well as other high capacity alloying electrodes that undergo large volume expansions during battery operations.

• Korean Journal of Environmental Agriculture
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• v.19 no.2
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• pp.183-187
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• 2000

Removal rate of nitrogen compound containing swine wastewater was 97 percent in case of high loading rate treatment of swine wastewater at studies for process development using soil microorganism. Minimum hydraulic retention time(HRT) for nitrification process was 11 days and solid retention time was 25 days. Nitrification was between 5 and 11 days but this time $NO_2-N$ was remained. Reactor condition was injured to nitrosomonas according to pH, $NO_2\;^--N$, and $NH_3\;^--N$ concentration but this condition was recover to pH controlling.

• Journal of Powder Materials
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• v.25 no.6
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• pp.466-474
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• 2018

The high theoretical energy density ($2600Wh\;kg^{-1}$) of Lithium-sulfur batteries and the high theoretical capacity of elemental sulfur ($1672mAh\;g^{-1}$) attract significant research attention. However, the poor electrical conductivity of sulfur and the polysulfide shuttle effect are chronic problems resulting in low sulfur utilization and poor cycling stability. In this study, we address these problems by coating a polyethylene separator with a layer of activated carbon powder. A lithium-sulfur cell containing the activated carbon powder-coated separator exhibits an initial specific discharge capacity of $1400mAh\;g^{-1}$ at 0.1 C, and retains 63% of the initial capacity after 100 cycles at 0.2 C, whereas the equivalent cell with a bare separator exhibits a $1200mAh\;g^{-1}$ initial specific discharge capacity, and 50% capacity retention under the same conditions. The activated carbon powder-coated separator also enhances the rate capability. These results indicate that the microstructure of the activated carbon powder layer provides space for the sulfur redox reaction and facilitates fast electron transport. Concurrently, the activated carbon powder layer traps and reutilizes any polysulfides dissolved in the electrolyte. The approach presented here provides insights for overcoming the problems associated with lithium-sulfur batteries and promoting their practical use.

• Journal of the Korean Wood Science and Technology
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• v.33 no.3 s.131
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• pp.64-71
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• 2005

In this study, we attempted to apply ultrasonic treatment for the preservative treatment of two softwood species, Korean pine and Japanese red pines to evaluate its effectiveness. Wood samples were submerged in oilborne preservative, copper naphthenate (NCU) and waterborne preservative, alkyl ammonium compound (AAC) and then treated with ultrasonic wave of 40 kHz, 400 W. After the treatment, the retention and penetration depth of these preservatives in the specimens were measured as a function of treatment time. Both the retention and penetration depth were continuously increased with increasing the treatment time up to 120 hours, where the retention reached about 95% by the application of AAC and the penetrating depth of 95% and 83% by the application of NCU, respectively for both species. The results of electronic microscopic observation showed that the improved retention capacity could be attributed to air deflation, wood extractive deflation working of ultrasonic wavelength, and destruction of wood pits which served as the pathway of preservatives. The results suggested that the use of ultrasonic treatment could be applied to thick wood veneers for the production of laminated wood products.

• Journal of the Korean Wood Science and Technology
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• v.27 no.2
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• pp.70-77
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• 1999

Objective of this research is to obtain fundamental data of carbonized wood wastes for soil condition, de-ordorization, absorption of water, carrier for microbial activity, and purifying agent for water quality of river. The carbonization technique and the properties of carbonized wood wastes(thinned trees) are analyzed. Proximate analysis shows the thinned wood contains 0.22-0.73% ash, 77-80% volatile matter, and 10-14% fixed carbon. The charcoal yield decreases and the shrinkage rate increases as the carbonization temperature and time increase. The charcoal yields of Larix leptolepis, Pinus rigida and Pinus densiflora are high, whereas those of Pinus koraiensis and Quercus variabilis are low. The shrinkage rate by carbonization has same trend as water removal of wood. The specific gravity after the carbonization decreases about 50% comparing to green wood. The charcoal has 0.89-4.08% ash, 6.31-13.79% volatile matter, and 73.9-83.5% fixed carbon. As the carbonization temperature and time increase, pH of charcoal increases. When the carbonization temperature is $400^{\circ}C$, pH is about 7.5. When the temperature is between 600 to $800^{\circ}C$, pH is about 10 with small difference. The water-retention capacity is not affected by the carbonization temperature and time. The water-retention capacity within 24hr is about 2.5 - 3times of sample weight, and the equivalent moisture content becomes 2-10% after 24 hr.

• Korean Journal of Food Science and Technology
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• v.3 no.1
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• pp.52-56
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• 1971

The cooked surf clam meat was treated with BHA or EDTA, and then dehydrated by means of hot-air dehydration or sun drying. The dehydrated products were packed in glass bottle and stored for three months in the dark place. After three month storage, the pigment loss and water absorbing capacity of dehydrated products were compared with those of directly after dehydration. Both of the sun dried and hot-air dehydrated surf clam products showed a great deal of pigment loss during storage. The BHA treatment prior to dehydration of surf clam meat had good effects on the pigment retention, and the EDTA treatment had a weak effect on it during storage. The rate of rehydration of dehydrated surf clam products had markedly decreased during storage. And it could be seen that there was little difference among the rate of rehydration of the BHA or EDTA treated product and untreated one during storage.

• Journal of Electrochemical Science and Technology
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• v.12 no.3
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• pp.346-357
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• 2021

In recent years, supercapacitors have been developed rapidly as a rechargeable energy storage device. And the performance of supercapacitors is depending on electrode materials, the preparation method and performance of electrode materials have become the primary goal of scientific development. This study synthesizes Co₃O₄@MnO₂@PPy cathode material with porous pattern core-shell structure by hydrothermal method and electrodeposition. The result samples are characterized by X-ray diffraction transmission/scanning electron microscope, and X-ray photoelectron spectroscopy. Electrochemical evaluation reveals that electrochemical performance is significantly enhanced by PPy depositing. The specific capacitance of Co₃O₄@MnO₂@PPy is 977 F g^-1 at 1 A g^-1, the capacitance retention rate of 105%. Furthermore, the electrochemical performance of Co₃O₄@MnO₂@PPy//AC asymmetric supercapacitor assembles with AC as the negative electrode material is significantly better than that of MnO₂//AC and Co₃O₄@MnO₂//AC. The capacity of Co₃O₄@MnO₂@PPy//AC is 102.78 F g^-1. The capacity retention rate is still 120% for 5000 charge-discharge cycles.