• Resources Recycling
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• v.27 no.6
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• pp.44-52
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• 2018

In this study, copper was recovered from copper containing sludge by selectively controlling electro-refining process conditions in copper sulfate electrolyte solution. Electro-refining process was performed by LSV (Linear Sweep Voltammetry) result according to copper sulfate electrolyte solution concentration, applied current density, additive type and concentration. SEM (Scanning Electron Microscope) and PSA (Particle Size Analyzer) were used to analyze the shape and size of copper powder. In the 0.1 ~ 0.4 M copper sulfate electrolyte solution without organic additives, the copper powder size decreased as the applied current density became closer to the limiting current density and the copper powder size tended to decrease in 0.2 ~ 0.3 M copper sulfate electrolyte solution. In addition, when the shape and size of the copper powder were analyzed by adding various types and concentrations of organic additives to the previous experimental, fine spherical copper powder having the smallest size (nm) was obtained under the condition of cellulose type additive 2,000 ppm.

• Korean Journal of Environmental Biology
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• v.18 no.1
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• pp.77-93
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• 2000

Field survey on the spatio-temporal distribution of water quality and chlorophyll a concentration, and the environmental factors on the variation of phytoplankton biomass were carried out at the 23 stations for four seasons in the Shiahae, southwestern coast of Korean Peninsula from February to October in 1995. I made an analysis on biological factor as chlorophyll a concentration as well as environmental factors such as water temperature, salinity and nutrients; ammonia, nitrite, nitrate, dissolved inorganic nitrogen, phosphate, N/P ratio, silicate and Si/P ratio. The waters in the Shiahae were not stratified due to the tidal mixing and high velocity of tidal current. And the high productivity in photic layer were supported by high nutrients concentration from freshwater on lands and bottom waters The low depth of transparency in the Shiahae had a bad influence upon primary production and marine biology. In Shiahae had a sufficient nutrients for primary production during a year. Especially dissolved inorganic nitrogen and silicate were high, the other side, phosphate was low. The source of nutrients in summer and silicate supply depend on input of freshwater from lands, the other side, dissolved inorganic nitrogen and phosphate were depend on rather supplied from bottom layer by the mixing and input of seawater from outside than input of freshwater from lands. Phosphate seemed to become a limiting nutrient for the primary production at all area of Shiahae in winter and at the northern parts in other seasons. However, dissolved inorganic nitrogen seemed to do it at the southern parts in other seasons except winter. Silicate didn't become a limiting nutrient for diatoms in Shiahae. Phytoplankton biomass as measured by chlorophyll a concentration was very high all the year round, it was controlled by the combination of the several environmental factors, especially of nitrogen, phosphorus and the physical factors such as light intensity. [Spatio-temporal distribution, Seasonal fluctuation, Nnutrients, Chlorophyll a, Environmental factors, Nutrient source, Limiting Nutrient, Light, Shiahae] .

• Korean Journal of Materials Research
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• v.15 no.4
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• pp.275-280
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• 2005

The growth of hafnium oxide thin films by atomic layer deposition was investigated in the temperature range of $175-350^{\circ}C$ using $Hf[N(CH_3)_2]_4\;and\;O_2$ as precursors. A self-limiting growth of $0.6\AA/cycle$ was achieved at the substrate temperature of $240-280^{\circ}C$. The films were amorphous and very smooth (0.76-0.80 nm) as examined by X-ray diffractometer and atomic force microscopy, respectively. X-ray photoelectron spectroscopy analysis showed that the films grown at $300^{\circ}C$ was almost stoichiometric. Electrical measurements performed on $MoW/HfO_2$(20 nm)/Si MOS structures exhibited high dielectric constant$(\~17)$ and a remarkably low leakage current density of at an applied field of $1.5-6.2\times10^{-7}A/cm^2$ MV/cm, probably due to the stoichiometry of the films.

• Applied Chemistry for Engineering
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• v.21 no.6
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• pp.621-626
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• 2010

Anion exchange membranes can be used for reverse electrodialysis for electric energy generation, and capacitive deionization for water purification, as well as electrodialysis for desalination. In this study, anion exchange membranes of poly((vinylbenzyl) trimethylammonium chloride-2-hydroxyethyl methacrylate)/poly(vinyl alcohol) were prepared through the polymerization of (vinylbenzyl)trimethylammonium chloride and 2-hydroxyethyl methacrylate in aqueous poly(vinyl alcohol) solutions, esterification with glutaric acid, and cross-linking reaction with glutaraldehyde. We investigated electrochemical properties for the anion exchange membranes prepared according to experimental conditions. Ion exchange capacity and electrical resistance for the membranes were changed with a variation in the monomer ratio in polymerization. Water uptake and conductivity for the membranes decreased with an increase in the content of glutaric acid in esterification. The change in the time of crosslinking reaction with the formed film and glutaraldehyde affected electrochemical properties such as water uptake, conductivity, or transport number for the membranes. Chronopotentiometry and limiting current density for the anion exchange membranes prepared were measured.

• Journal of the Korean Dietetic Association
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• v.16 no.1
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• pp.1-12
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• 2010

This study was conducted to characterize well-being menus and to examine the service frequency and profitability of those served in the contract-managed workplace foodservice. In-depth interviews were conducted with six persons who were in charge of menu management in the headquarters of six different foodservice management companies during March, 2007. In addition, 122 set menus consisting of 777 menu items, which were on one month menus served during January to April, 2007, were collected from three workplace operations managed by three different foodservice management companies. As a result of the in-depth interviews, four categories of well-being menu items were extracted: 'medicinal functional menu item', 'environmentally-friendly menu item', 'natural food menu item', and 'harmful components-limiting menu item'. Accordingly, a well-being menu item was defined as 'a menu item with increased nutrition value or decreased health risk by changing food material or cooking method'. When the menu items (n=777) were analyzed by applying the definition and categories, approximately 14% of the items were identified as well-being menu items and most of them were either medicinal functional (65%) or natural food menu items (33%). Approximately 59% of the 122 set menus included at least one well-being menu item, and therefore they were named the well-being set menus. These well-being set menus, however, were not significantly different from the rest set menus in terms of profitability as measured by the contribution margin. The results of this study could be useful for foodservice management companies to develop and plan well-being menus targeting workplace foodservice operations.

• Fashion & Textile Research Journal
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• v.20 no.3
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• pp.279-286
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• 2018

This study conducted a qualitative research based on interviews with school teachers and instructors operating external activities about how the management of one's own appearance influence the changes in subjective happiness and self-esteem by focusing on maladjusted students of two alternative schools and ordinary middle and high schools in Gyeongsangnam-do province. Happiness refers to a positive emotion that can be felt continuously throughout life such as life satisfaction, good experience, and positive way of thinking. The sense of happiness is the satisfaction that one feels by interpreting and evaluating his or her experience in a positive way and can be defined as the positive emotions that can be felt when one perceives and uses the strengths and resources that he or she has. Although the self-esteem is formed, changed, and developed throughout life, the self-awareness and self-evaluation develop more actively than other stages of development particularly in adolescence, and the adolescents with low self-esteem are faced with more serious behavioral, scholastic, and psychological issues. I hope the results of this study not only help current adolescents at risk to improve their self-esteem but also become a chance to see the issue of adolescents at risk as a part of social issue instead of limiting the issue as personal or domestic issue by expanding the application scope of the results to adolescents in middle schools and high schools who have the potential of going astray in order to approach the issue on the level of the entire society.

• Journal of the Korea Society of Computer and Information
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• v.6 no.2
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• pp.8-13
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• 2001

We demonstrate a pulsed CO$_2$laser with long pulse duration of millisecond order in the low pressure less than 30 Torr. A new power supply for our laser system switches the voltage of AC power line(60㎐) directly. The power supply doesn't need elements such as a rectified bridge, energy-storage capacitors. and a current-limiting resistor in the discharge circuit. In order to control the laser output power, the pulse repetition rate is adjusted up to 60㎐ and the firing angle of SCR gate is varied from 30˚ to 150˚. A ZCS(Zero Crossing Switch) circuit and a PIC one-chip microprocessor are used to control the gate signal of SCR precisely. The maximum laser output is 23W at the total pressure of 18 Torr, the pulse repetition rate of 60㎐, and SCR gate firing angle of 90˚. In addition, the obtained laser pulse width is approximately 3㎳(FWHM)

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.8 no.1
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• pp.151-159
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• 1998

Elelctrical properties of $BaTiO_3$ were characterized with addition of $Y_2O_3, CaO,SiO_2$ and Mn to develope the composition of PTC thermistor suitable as a current limiting device for automobile motor system. With the addition of 0.2 mol% $Y_{2}O_3$ to $BaTiO_3$, the minimum resistance of 16.5 ${\Omega}{\cdot}$cm was obtained at room temperature. $(Ba_{0.996}Y_{0.004})TiO_3$ exibited a minimum resistance of 50${\Omega}{\cdot}$cm with addition of 1.6 mol% $SiO_2$. The grain size of $(Ba_{0.996}Y_{0.004})TiO_3$ decreased from 34.95 ${\mu}$m to 13.4 ${\mu}$m and thus breakdown voltage could be improved by changing the composition as $(Ba_{0.996}Y_{0.004}Ca_{0.05}) TiO_3$ with substition of 5 mol% Ca into Basites. When 0.04 mol% Mn was added, the optimum PTCR properties could be obtained : the resistivity at room temperature and ${\rho}_{max}/{\rho}_{min}$ were 30~40${\Omega}{\cdot}$cm and $1.5{\times}10^5$ respectively.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.35 no.1
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• pp.43-51
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• 2011

Natural convection heat transfer phenomena on a horizontal cylinder have been studied experimentally in order to investigate the applicability of analogy experimental methodology using a copper electroplating system and to visualize the local heat transfer rates depending on the angular position and the diameter of the horizontal cylinder. In the copper electroplating system, the copper ion produced at the anode moves by convection and diffusion to the cathode and reduces at the cathode, representing the heat transfer. By using aluminum cathode with a distinguishable color, the amount of copper plated could visualize the amount of heat transferred depending on the angular position of the cylinder. The diameter of the cylinder is varied from 0.01m to 0.15m, which correspond to Rayleigh numbers in the range of $1.73{\times}10^7$ to $5.69{\times}10^{11}$. The test results are in good agreement with existing heat transfer correlations.

• Journal of Korean Society for Quality Management
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• v.43 no.2
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• pp.141-150
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• 2015

Purpose: The purpose of this paper is to motivate small/medium business challenged masterpiece development and to develop masterpiece strategic system. Methods: Each checklists are developed based on WC300 (World Class 300) and MQI (Masterpiece Quality Index). Correlation between the evaluation items about MQI and WC300 is analyzed. MQI is derived associated with main improvement areas of WC300 through IPA (Importance Performance Analysis). Compliance and ranking are analyzed through HOQ (House Of Quality) using masterpiece quality main factor and limiting factor. Strategy establishment base is secured through improvement derivation and correlation analysis between MQI and GQM 4.0(Global Quality Management 4.0). Results: Detail strategy is derived considering work condition about small/medium business's three kinds of industries (machine, electric and electronic). Conclusion: It is necessary to determine the potential capacity of the current domestic small/medium businesses. Small/medium businesses should be given the opportunity to self identify and manage their strengths and improvement.