• Resources Recycling
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• v.25 no.1
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• pp.60-67
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• 2016

A scale-up test with a continuous solvent extraction and electro-winning system was carried out to separate and recover copper from a synthetic sulfuric acid solution (Cu 10.5 g/L, Co 2.0 g/L, Ni 15.0 g/L, Fe 0.2 g/L). The solution was introduced into mixer-settlers with four stages of extraction and two stages of stripping for continuous countercurrent solvent extraction to separate copper from nickel and cobalt. The loading was carried out using 40% LIX 84-I(v/v) as extractant with a phase ratio of A : O = 1 : 1. Meanwhile, the stripping was undertaken at a phase ratio of A : O = 1 : 1.5 using depleted electrolyte containing 35.0 g/L Cu and 180 g/L $H_2SO_4$ as stripping solution. The extraction and stripping efficiencies were found to be 96.7% and 91.0%, respectively. The copper composition of the stripped solution (pregnant electrolyte) was 50.0 g/L Cu with impurities of 25 ppm nickel, 5 ppm cobalt and 3 ppm iron. In the electro-winning process, copper metal of 99.833 purity was yielded with current efficiency of 98.9% and current density of $1.50A/dm^2$.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.39 no.1 s.119
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• pp.48-55
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• 2007

The aim of this article is to review the general property of the famous traditional Korean paper, "rice straw paper"(Bast-Fiber mixed with straw pulp), and to compare the paper qualities varying with the composition ratio of straw pulp, in order to revive the traditional paper in modem Korea. The experiment was carried out by making first the two different mixture papers, i. e., one is the paper of 50% bast fiber mixed with 50% straw pulp, and the other is the paper of 75% bast fiber with 25% oats straw pulp, and finally the 100% bast fiber paper was made for the purpose of comparison. The qualitative properties of these three kinds of paper with the different mixing ratio of the straw pulp were evaluated, and the findings of the experiment can be summarized as follow: 1. As to the quality aspects of the paper strength like tensile strength, breaking length, elongation, and tear strength, the test proved the 100% bast fiber paper as best, and the 50% mixed paper as the next good one. 2. In aspect of the printing adaptability such as density, opacity, brightness, whiteness, lab colors, air permeability, and roughness, the 50% mixed paper proved to be the best, due to the short cells in the straw pulp. 3. As to the air permeability, the larger ratio of straw pulp was found to be the lesser, and 75% bast fiber with 25% straw pulp mixture paper and the 100% bast fiber one were found 1/5 degree efficient. 4. In terms of the water absorption degree, 100% bast fiber paper was the fastest, but in case of mixture paper, 50% mixed one was a little faster up to the point of 1cm, while the two kinds of mixed ones appear to be almost similar to each other beyond the point. 5. The straw pulp mixed paper, especially the 50% mixed one was evaluated as the highest by the calligraphers who had experienced using the papers in terms of movement and feeling of the caligraphy and painting. In addition, although the 25% mixed paper is judged to be good for book printing because of the strength, the 50% mixed paper can be thought to be more desirable for painting and calligraphy. In conclusion, we will be able to make the quality paper with durability, by mixing the straw pulp with the bast fiber in proper ratio, following the tradition of Korean paper making.

• Journal of Korean Society of Transportation
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• v.21 no.3
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• pp.47-56
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• 2003

Considering the high density developments along the major traffic corridors in Seoul, transit-oriented street designs will be a very effective to control traffic congestion along the corridors. For testing the effectiveness, we selected. for our case study, Kangnam Street, which is one of the most highly developed corridors in Seoul The traffic study on Kangnam street in 2000 shows that the daily average bus speed is 11.73km/h, which is 5km/h lower than the auto speed. The Central Bus Lane system was applied on the Kangnam street to test impact on bus speed as well as auto speed. Simulation results show that with Central Bus Lane have been improved the travel speeds of bus as well as auto on Kangnam street from 14.4km/hr to 35.0km/hr and from 25.1km/hr to 26.1km/hr, respectively. The bus market share increases about 6-8 percentages. Especially, 13.4% of bus users are increased for long-distance trips.

• Journal of Veterinary Clinics
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• v.30 no.2
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• pp.115-118
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• 2013

An 8-year-old spayed female domestic shorthair cat was presented with a chief complaint of chronic nasal discharge and dyspnea. Physical examination revealed pyohemorrhagic nasal discharge, inspiratory dyspnea and stertor, and an enlarged right mandibular lymph node. Abnormalities of blood works and serum chemistry included mildly increased hematocrit, and globulin concentration. Serologic tests for FeLV and FIV, and a panel of polymerase chain reaction tests for Chlamydophila felis, Feline Calicivirus, Herpesvirus, Bordetella, Mycoplasma felis, and H1N1 influenza was all negative. Only radiographic finding showed increasing soft tissue density in the right nasal cavity and computed tomography disclosed soft tissue/fluid opacification in the right nasal cavity, paranasal sinus, and pharyinx along with slight deviation to the right of the osseous nasal septum. Focal lysis of ventral nasal septum was also suspected in CT scan. Cytological evaluation of fine needle aspirate smears of the enlarged mandibular lymph nodes revealed numerous fungal yeasts having variably thick capsule both extracellularly and intracellularly with low numbers of macrophages. Some yeasts showed narrow based budding, which was a consistent finding with Cryptococcus organisms. Serum protein electrophoresis was a polyclonal consistent with chronic infection and serum was submitted for a fungal serology panel test. In serologic tests Cryptococcus antigen titer was 1 : 32,768. In vitro culture was unsuccessful. Treatment was initiated with administration of fluconazole, clindamycin, and tocopherol. Clinical signs resolved within 3 days after the initial treatment. The cat was discharged and scheduled for periodic evaluation and continued therapy, but was lost to follow-up thereafter.

• Korean Journal of Materials Research
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• v.10 no.10
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• pp.665-670
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• 2000

Linear annealing method was developed to increase the bond strength of Si wafer pair mated at room tem­perature instead of conventional furnace annealing method. It has been known that the interval of the two mating wafer surfaces decreases and the density of gaseous phases generated at the interface increases with increase in an-nealing temperature. The new annealing method consisting of one heat source and light reflecting mirror used these two phenomena and was applied to Si$\mid$$\mid$Si and Si$\mid$$\mid$$SiO_2/Si$ bonding. The bonding interface observed directly by using IR camera and HRTEM showed clear bonding interface without any unbonded areas except the area generated by the dusts inserted into the mating interface at the room temperature. Crack opening method and direct tensile test was ap­pplied to measure the bond strength. The two methods showed similar results. The bond strength increased continuous­tly with the increase of annealing temperature.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.31 no.3
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• pp.256-263
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• 1995

This paper presents the evidence on the considerably strong stratification - destratification(SD) phenomena during spring - neap tidal cycle in summer of 1992 based on the observed temperature, salinity and density data. To find out the main factors causing SD in the bay, we computed the rate of potential energy balance of the surface heat flux, tidal and wind stirring proposed by Simpson and Hunter (1974) and Simpson and Bowders (1981) using observed data. It was found that the energy of the wind stirring was one - order smaller than those of the heat flux and the tidal stirring. It means that the variation of stratification phenomena in the bay mainly depend on tidal stirring and sea surface heating in summer if there was no exceptionally strong wind event like a typhoon. Finally, we tested the effects of typhoon on the mixing characteristics of the bay using the example of a empirical typhoon model. It was found that when wind speed is larger than 15m/sec in Deukryang Bay, the wind energy was always larger than the average heating energy based on empirical typhoon model test. Particularly, typhoon passed on the left side of the bay, strong wind energy happened, which is almost the same as tidal energy of spring tide.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.8
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• pp.3719-3725
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• 2012

Due to the recent shortage of well-graded river sand resulting from a rapid growth of concrete construction, sea sand, crushed sand, and etc. are increasingly used instead. It is, however, well noted that non-washed sea sand leads to corrosion of the reinforcing steel in concrete, and thus eventually results in damage to concrete. Also, the crushed sand is not being widely used, since it is difficult to maintain the allowable amount of passing 0.08mm sieve and to adjust grading. On the other hand, because the fine sand of Nakdong-River has a poor grading but good quality as a fine aggregate for concrete, it is strongly needed to investigate the fine sand as an alternative fine aggregate. Thus, the purpose of this research is to evaluate the physical properties of the fine sand of Nakdong-River to utilize it actively as a fine aggregate. For this purpose, after the sand samples were collected according to typical location of main stream of Nakdong-River, the physical properties such as density in oven-dry condition, grading, unit volume mass, and etc. of them were estimated. It was observed from the test results that physical properties of the fine sand of Nakdong-River except grading were found to be excellent.

• Korean Journal of Remote Sensing
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• v.24 no.2
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• pp.107-115
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• 2008

Recently, a considerable number of studies have been conducted on the high resolution imagery showing the boundaries of objects clearly. When urban areas are analyzed in detail using the high resolution imagery, the size of analyzed zone is apt to be decided arbitrarily. Sufficient prior information about study area makes the decision of analysis zone possible; otherwise, it is difficult to determine the optimized analysis zone using only satellite imagery. In this study, the variograms of artificial simple images are analyzed before applying to the real satellite images. As a result of the analysis of simple images, the sill has an effect on the density of objects and also the size of objects and spacing influence the range. The variograms of real satellite images are analyzed with reference to the result of model test and are applied to determining the optimized analysis zone. This study shows that variogram can be applied to determining effectively the optimized analysis zone in case of no prior information on study area; moreover it will be expected to be used for an index to express the characteristics of urban imagery as well as conventional kriging and simulation.

• KEPCO Journal on Electric Power and Energy
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• v.5 no.3
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• pp.141-147
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• 2019

Recently, the biggest issue in the electricity industry is the increase in renewable energy, and various technologies are being developed to ensure the capacity of the power system. In addition, super-grids linking power systems are being pushed to utilize eco-friendly energy between countries and regions worldwide. The HVDC transmission technology is required to link the power network between regions with different characteristics of the power system such as frequency and voltage. Until now, Korea has applied HVDC transmission technology that connects mainland and Jeju Island with submarine cables. But, the HVDC transmission technology is still developing for long-distance high-capacity power transmission from power parks on the east coast to load-tight areas near the metropolitan area. Considering the high population density and mountainous domestic environment, it is pushing for commercialization of the design technology of the ${\pm}500kV$ Double Bipole with metallic return wire transmission line to transmit large-scale power of 8 GW using minimal right of ways. In this paper, the insulation characteristics were studied for the design of double-bipole transmission tower with metallic return wire, which is the first time in the world. And the air insulation characteristics resistant to the various overvoltage phenomena occurring on transmission lines were verified through a full-scale impulse voltage test.

• Food Science and Preservation
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• v.24 no.3
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• pp.421-430
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• 2017

This study was conducted to investigate the effect of Lentinus edodes powder on the quality characteristics and antioxidant of rice cookies. The cookies for this experiment was made by 3 main ingredients including rice powder, flour, Lentinus edodes powder. The proportion of rice powder was fixed to 50% for the total amount of ingredients. The amount of reminded 2 ingredients (flour and Lentinus edodes powder) were varied. The amount of flour was decreased up to 38%, and the addition of Lentinus edodes powder was increased to 4%, 8% and 12%. Density of the dough, hardness, total polyphenol content, DPPH free radical scavenging activity, and reducing power increased with increasing Lentinus edodes powder content. Moisture content, pH of the dough, spread factor, loss rate, leavening rate, and L values of the cookies were decreased with increasing Lentinus edodes powder content. The result of consumer acceptance test revealed that there were no significant differences in smell, taste and overall acceptability, while the preference of color decreased as the amount of Lentinus edodes powder increased. To sum up, the cookies with 12% Lentinus edodes powder can produced the best results in terms of quality and antioxidant potential.