• Journal of the Korea Academia-Industrial cooperation Society
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• v.8 no.2
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• pp.380-384
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• 2007

The COD removal capacity of aquatic plants, when foamed glasses were not used, showed 56% for Pistia straiotes, 48% for Phragmites japonica and 41% for Oenanthe javanica, but no significant COD removal was observed for Lythrum anceps. When the foamed glasses were used as support materials, the COD removal efficiency increased for all aquatic plants used in this study showing 69% fur Pistia straiotes, 68% for Pharagmites japonica 62% for Oenanthe javanica, respectively. The T-N removal efficiency of aquatic plants when foamed glasses were used as support materials showed 91% for Lythrum anceps and 93% for Phragmites japonica. Similar removal efficiency was observed as 94% for all aquatic plants planted as a group used in this study. The T-P removal efficiency of aquatic plants when foamed glasses were not used showed 35% for Lythrum anceps, 8% for Phragmites japonica, however, that, when foamed glasses were used, ranged 78% for Lythrum anceps, 43% for Phragmites japonica, showing that the foamed glasses increase the T-P removal efficiency of aquatic plants used in this study.

• Journal of Korean Library and Information Science Society
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• v.26
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• pp.131-168
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• 1997

The future of a country is influenced by the youth. Sound fostering of the youth is important for the country's future. Because of mechanization, industrialization and urbanization of our society, many social problems, such as confusion of the sense of value, dehumanization, money worshi n.0, ppings, juvenile delinquency are increasing. For the solution of problems of juvenile crime and dehumanization, bibliotherapy should be practiced in juvenile reformatories, schools and societies. The purpose of this study is to investigate the effectiveness and value of reading. And also the characteristics, brief history, principles and procedures of bibliotherapy are examined. In addition, the book catalog suitable for bibliotherapy is considered. The results of the study are as follows. (1) In order to solve the problem of dehumanization, and the confusion of the sense of value among young adults, we should enrich and cultivate the characters of young adults through the bibliotherapy. So, bibliotherapy for the treatment of human nature of juveniles should be practiced in the juvenile reformatories, schools and societies. (2) The values of reading in the past were inspiration, information and recreation. But, in recent times, the interest in therapeutic value of reading is increasing. (3) Bibliotherapy is a kind of psychotherapy using selected reading materials. A n.0, pplication scopes of bibliotherapy are very wides, including mental medicine, alcoholic poisoning, drug addiction, juvenile delinquency, counselling and education for school life, etc. (4) The principles of bibliotherapy consist of identification, catharsis, insight and it has self therapeutic principles through the reading. The procedures of bibliotherapy is similar to any other kind of psychotherapy: the participant's statement, diagnosis, treatment, continuous recognition of remedial value. (5) The well suited reading materials for bibliotherapy are literature and biography. Literature and biography are familiar to everyone, because they describe the mentalities, emotions and life styles of human beings. (6) The standard reading lists for bibliotherapy for the proper guidance of juvenile delinquency should be prepared for the solution of developmental tasks, such as, drinking, smoking, friendship, family, love, money, marriage, pregnancy, violence, etc. Finally, Bibliotherapy should be introduced to our school settings and corrections institutions for the proper guidance and prevention of the malpractice of the youths. In addition, we should be endeavor to develop the standard reading lists for bibliotherapy and case study.

• Resources Recycling
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• v.27 no.5
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• pp.49-53
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• 2018

In developing an optimum steelmaking process, the purity of the product, environmental impact, capability and cost of the process should be considered. Desulfurization of molten iron is conducted during preliminary treatment stage before converter operation. Although fluorite is added as a desulfurizing agent in CaO and $CaCO_3$ based agents, the concentration of fluorine in slag is strictly regulated. In order to develop desulfurizing agent without fluorine, CaO was mixed with Al dross and ladle slag containing alumina. The characteristics and desulfurizing capacity of the CaO based desulfurizing agent thus prepared were tested by varying temperature of Kanvara Reactor. Our results showed that the desulfurizing capacity of the samples prepared in this work was found to be similar to that of the traditional desulfurizing agents with fluorine.

• Korean Journal of Materials Research
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• v.23 no.8
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• pp.430-434
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• 2013

Quantum dots(QDs) with their tunable luminescence properties are uniquely suited for use as lumophores in light emitting device. We investigate the microstructural effect on the electroluminescence(EL). Here we report the use of inorganic semiconductors as robust charge transport layers, and demonstrate devices with light emission. We chose mechanically smooth and compositionally amorphous films to prevent electrical shorts. We grew semiconducting oxide films with low free-carrier concentrations to minimize quenching of the QD EL. The hole transport layer(HTL) and electron transport layer(ETL) were chosen to have carrier concentrations and energy-band offsets similar to the QDs so that electron and hole injection into the QD layer was balanced. For the ETL and the HTL, we selected a 40-nm-thick $ZnSnO_x$ with a resistivity of $10{\Omega}{\cdot}cm$, which show bright and uniform emission at a 10 V applied bias. Light emitting uniformity was improved by reducing the rpm of QD spin coating.At a QD concentration of 15.0 mg/mL, we observed bright and uniform electroluminescence at a 12 V applied bias. The significant decrease in QD luminescence can be attributed to the non-uniform QD layers. This suggests that we should control the interface between QD layers and charge transport layers to improve the electroluminescence.

• 보존과학연구
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• s.21
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• pp.233-271
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• 2000

This study has proved if there are homogeneities in crystal structures, firing temperaures and element compositions of 69 specimens for potteries and soils from Changdo, Kangjin-gun, Jinjuk-Ri in Korea and Yaezhou inChina and obtained the following results.1. XRD analyses showed that soft potteries seemed to contain ($\alpha$)quartz, feldspar, while hard potteries seemed to contain ($\alpha$-)quartz, mullite, tridymite, feldspar. Jinjuk-Ri soils consisted of clays such as Kiolinite, Montmorillonite, Muscovite, Illite and, mica and feldspar etc.2. It was estimated that the firing temperatures which are determined by crystals using XRD, ranged from $550^{\circ}C$ to $870^{\circ}C$ for soft potteries and $870^{\circ}C$ to $975^{\circ}C$ for hard potteries.3. The firing temperatures for 4-pieces of Changdo pottery were measured by using TG-DTA, and it was found that specimen No. 10 was fired at temperatures below $600^{\circ}C$, while specimens No. 14, No. 23 and No. 29 were fired at temperatures above $1000^{\circ}C$.4. It was found that the specimems for potteries and porcelains from Changdo, Kangjin-gun, Jinjuk-Ri in Korea and Yaezhou in China were apparently classified into 4 clusters. This suggests that there are no correlations between the raw materials used in each 4 regions. Among the porcelains from Changdo, there were many typologically similar ones to those from Yaezhou in China in the 9th centry, but the analyses of porcelains only from Changdo, Kangjin in Korea and Yaezhouin China showed that they were classified into 3 clusters. This suggest that there are no correlations between the raw materials used for making porcelains in Changdo, Kangjin-gun, Jinjuk-Ri in Korea and Yaezhou in China.

• Journal of Korean Society of Water and Wastewater
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• v.21 no.5
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• pp.621-629
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• 2007

This study intends to investigate the characteristics of the foul smell of sewer pipes near large apartment complexes as complaints about offensive odors have drastically increased in urban residential areas. Targeting apartments where people actually complained about foul orders, the study result revealed that components in the smell of the water-purifier tank of the target apartment were very similar to those of sewage treatment plants and night soil treatment plants. Measuring components of odors inside the management layer of tank showed that the concentration of hydrogen sulfide was 10ppm, which is approximately 160 times the safety standard of 0.06ppm; the concentration of mercaptan was 0.9ppm, which is about 220 times the safety standard of 0.004ppm. The source materials of foul odors were discharged outside through ducts, and those households living near outlets producing bad smell complain that it gets worse depending on the air pressure or wind direction and strength, and they could not even open windows. As well, these source materials were transferred by discharge pumps to public sewer pipes outside the apartment complex. While discharge pumps starts operating, they remain on the sewer pipe and then begin to spread over to roads through small openings of manholes on the road. Then, the smell offends passers-by and residents near the road, leading to a lot of complaints. The study results suggest that, among the sources of foul odors in sewer pipes of residential areas, especially those from the water-purifier tank of large apartments, hydrogen sulfide should be the main target for follow-up treatment.

• Tribology and Lubricants
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• v.36 no.2
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• pp.88-95
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• 2020

In this study, we investigate the mechanical properties of high manganese steel, and the friction and wear characteristics of brake friction material containing this steel, for passenger car application, with the aim of replacing copper and copper alloys whose usage is expected to be restricted in the future. These steels are prepared using a vacuum induction melting furnace to produce binary and ternary alloys. The hardness and tensile strength of the high manganese steel decrease and the elongation increases with increase in manganese content. This material exhibits high values of hardness, tensile strength, and elongation; these properties are similar to those of 7-3 brass used in conventional friction materials. We fabricate high manganese steel fibers to prepare test pad specimens, and evaluate the friction and wear characteristics by simulating various braking conditions using a 1/5 scale dynamometer. The brake pad material is found to have excellent friction stability in comparison with conventional friction materials that use 7-3 brass fibers; particularly, the friction stability at high temperature is significantly improved. Additionally, we evaluate the wear using a wear test method that simulates the braking conditions in Europe. It is found that the amount of wear of the brake pad is the same as that in the case of the conventional friction material, and that the amount of wear of the cast iron disc is reduced by approximately 10. The high manganese steel is expected to be useful in the development of eco-friendly, copper-free friction material.

• Korean Journal of Materials Research
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• v.12 no.8
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• pp.600-607
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• 2002

The Ni-Zn synthetic ferrite were acquired from thermally decomposing the metal nitrates Fe(NO$_3$)$_3$.$9H_2$O, Zn($NO_3$)$_2$.$6H_2$O, Ni($NO_3$)$_2$. $6H_2$O, and Cu($NO_3$)$_2$. $3H_2$O at $150^{\circ}C$ for 24 hours and was calcined at $500^{\circ}C$. Each of those was pulverized for 3, 6, 9, and 12 hours in a steel ball mill and was sintered between $700^{\circ}C$ and $1,000^{\circ}C$ for 1 hour, and then their microstructures and electromagnetic properties were examined. We could make the initial specimens chemically bonded in liquid at the temperature as low as $150^{\circ}C$, by using the melting points less than $200^{\circ}C$ of the metal nitrates instead of the mechanical ball milling, then narrowed a distance between the particles into a molecular level, and thus lowed sintering temperature by at least $200^{\circ}C$ to$ 300^{\circ}C$. Their initial permeability was 50 to 400 and their saturation magnetic induction density and coercive force 2,400 G and 0.3 Oe to 0.5 Oe each, which were similar to those of Ni- Zn ferrite synthesized in the conventional process. In the graph of initial permeability vs frequencies, we could observe a $180^{\circ}C$rotation of the magnetic domain, which appears in a broad band of microwave near the resonance frequency.

• Korean Journal of Materials Research
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• v.5 no.1
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• pp.140-148
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• 1995

Optical properties of $TiO_{2}$. Ag filrns and $TiO_{2}/Ag/TiO_{2}$ multilayer filrns with different thickness were predicted using the transfer matrix, and these results were compared with real transmittance curves of the sputterdeposited films. With the complex refractive indices, it was possible to predict transmittance characteristics which were close to real data for $TiO_{2}$ and Ag films. Due to the diffusion and agglomeration of Ag during $TiO_{2}$ deposition, optical properties of the sputterdeposited $TiO_{2}/Ag/TiO_{2}$ films were found to be very different from the transmittance curves predicted using the transfer matrix. Using deposition of 4nm-thick or 6nm-thick TI layers as a diffusion barrier, however, the transmittance curves of $TiO_{2}/Ti/Ag/Ti/TiO_{2}$ five-layer films became similar to ones predicted for $TiO_{2}/Ag/TiO_{2}$ threeiayer films.

• The Journal of Advanced Prosthodontics
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• v.9 no.5
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• pp.387-393
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• 2017

PURPOSE. Beverages may affect the translucency of esthetic dental restorative materials.The aim of the present study was to investigate the effects of coffee and red wine on the translucency of a PICN material with two translucency levels, and finished with different methods. MATERIALS AND METHODS. 2M2 high translucent and translucent VITA Enamic hybrid ceramic blocks were investigated. Rectangular specimens with the dimensions of $12mm{\times}14mm{\times}2mm$ were prepared. The specimens were finished and polished with different methods as suggested by the manufacturer. The translucency parameters of the specimens were evaluated before and after 24 hours, 7 days, and 28 days immersion in distilled water, coffee and red wine. Translucency parameters were measured using a portable spectrophotometer. RESULTS. At the end of 28 days, there was no statistically significant difference between the groups of specimens kept in coffee (P>.05). In the red wine groups, there was a statistically significant difference between the control group and all other groups (P<.05) at the end of 28 days. CONCLUSION. The translucency of hybrid ceramic for a restoration may not be important regarding the effects of coffee on translucency change because the specimens with different translucencies and finishing methods that were immersed to coffee had similar translucency parameters at the end of 28 days. The translucency of hybrid ceramic may be important in the case of red wine, however, since the results showed that highly translucent specimens exposed to red wine demonstrated better translucency parameters than specimens made from translucent blocks at the end of 28 days.