• Journal of Conservation Science
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• v.26 no.3
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• pp.213-228
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• 2010

The composition of Chinese ceramic shards has been the subject of analysis in Europe, beginning in the 18th century, and in China from the 1950s. Scientific studies of traditional Korean shards commenced in the United States and Germany in the 1980s, and studies within Korea began in the 1990s. From analysis of a large systematically collected dataset, the composition of porcelain produced during the Kory. dynasty, including 21 celadon and 10 whiteware groups, was characterized and compared with that of Chinese ceramics. The average composition of the body and glaze of several shards (usually three to five) from each group was determined, enabling comparisons between groups. The results show that the majority of groups were derived from mica-quartz porcelain stone, which was commonly used in Yuezhou, Jingdezhen, and other southern Chinese kilns. The composition of glazes includes clay and flux components; the latter were typically wood ash and limestone, initially as burnt but later as crushed forms. The earliest of the Kangjin glazes contained substantially less titanium oxide than did the Yuezhou glazes, which were typically formulated from body material and wood ash. The present study provides a comparative framework for the growing number of analytical investigations associated with excavations occurring in Korea.

• 한국신재생에너지학회:학술대회논문집
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• 2006.11a
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• pp.348-351
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• 2006

Bipolar plate, which forms about 50% of the stack cost, is an important core part with polymer electrolyte membrane in PEMFC. Bipolar plates have been commonly fabricated from graphite meterial having high electrical conductivity and corrosion resistance. Lately, many researchers have concentrated their efforts on the development of metallic bipolar plate and stainless steel has been considered as a potential material for metallic bipolar plate because of its high strength, chemical stability, low gas permeability and applicability to mass production. However, it has been reported that its inadequate corrosion behavior under PEMFC environment lead to a deterioration of membrane by dissolved metal ions and an increase in contact resistance by the growth of passive film therefore, its corrosion resistance as well as contact resistance must be improved for bipolar plate application. In this work, several types of coating were applied to 316L and their electrical conductivity and corrosion resistance were evaluated In the simulated PEMFC environment. Application of coating gave rise to low interfacial contact resistances below $19m{\Omega}cm^2$ under the compress force of $150N/cm^2$. It also made the corrosion potential to shift in the posit ive direct ion by 0.3V or above and decreased the corrosion current from ca. $9{\mu}A/cm^2$ to ca. $0.5{\mu}A/cm^2$ in the mixed solution of $0.1N\;N_2SO_4$ and 2ppm HF A coat ing layer under potentiostatic control of 0.6V and $0.75V_{SCE}$ for 500 hours or longer showed some instabilities, however, no significant change in coat Ing layer were observed from Impedance data. In addition, the corrosion current maintained less than $1{\mu}A/cm^2$ for most of time for potentiostatic tests. It indicates that high electrical conductivity and corrosion resistance can be obtained by application of coatings in the present work.

• Journal of Microbiology and Biotechnology
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• v.26 no.10
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• pp.1708-1716
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• 2016

Glucose dehydrogenase (GDH) is an oxidoreductase enzyme and is used as a biocatalyst to regenerate NAD(P)H in reductase-mediated chiral synthesis reactions. In this study, the glucose 1-dehydrogenase B gene (gdhB) was cloned from Bacillus thuringiensis subsp. kurstaki, and wild-type (GDH-BT^WT) and His-tagged (GDH-BT^N-His, GDH-BT^C-His) enzymes were produced in Escherichia coli BL21 (DE3). All enzymes were produced in the soluble forms from E. coli. GDH-BT^WT and GDH-BT^N-His showed high specific enzymatic activities of 6.6 U/mg and 5.5 U/mg, respectively, whereas GDH-BT^C-His showed a very low specific enzymatic activity of 0.020 U/mg. These results suggest that the intact C-terminal carboxyl group is important for GDH-BT activity. GDH-BT^WT was stable up to 65℃, whereas GDH-BT^N-His and GDH-BT^C-His were stable up to 45℃. Gel permeation chromatography showed that GDH-BT^WT is a dimer, whereas GDH-BT^N-His and GDH-BT^C-His are monomeric. These results suggest that the intact N- and C-termini are required for GDH-BT to maintain thermostability and to form its dimer structure. The homology model of the GDH-BT^WT single subunit was constructed based on the crystal structure of Bacillus megaterium GDH (PDB ID 3AY6), showing that GDH-BT^WT has a Rossmann fold structure with its N- and C-termini located on the subunit surface, which suggests that His-tagging affected the native dimer structure. GDH-BT^WT and GDH-BT^N-His regenerated NADPH in a yeast reductase-mediated chiral synthesis reaction, suggesting that these enzymes can be used as catalysts in fine-chemical and pharmaceutical industries.

• Journal of the Korean Society of Marine Environment & Safety
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• v.26 no.6
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• pp.681-688
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• 2020

Approximately 6,000 chemicals are transported through the sea, including hazardous and noxious substances (HNS), which cause marine pollution and are harmful to marine life. The HNS discharged into the sea during the maritime transportation process undergoes physical and chemical changes on the sea surface and in seawater, and some types of HNS sink and are deposited on the seabed. The HNS deposited on the seabed adversely affects the benthic ecosystem, and hence, it is desirable to detect, treat, and recover the HNS on the seabed. Therefore, this study was conducted to analyze the performance requirements that should be considered as the top priority when developing a mechanical system for recovering the HNS deposited on the seabed. Various types of existing dredging devices used for collecting and recovering pollutants from river beds and seabeds were investigated, and 10 performance indices for the mechanical devices were selected. The new performance requirements for the development of the seabed-deposited HNS recovery system were proposed using performance indices. By considering the depth of water in domestic seaports, some of the performance requirements of the mechanical system for recovering deposited HNS from the seabed were obtained as follows: production rate (50-300 ㎥/hr), maximum operation depth (50 m), sediment type (most forms), percentage of solids (10 % or higher), horizontal operating accuracy (±10 cm), limiting currents (3-5 knots). These performance requirements are expected to be useful in the conceptual and basic design of mechanical systems for recovering seabed-deposited HNS.

• Tuberculosis and Respiratory Diseases
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• v.47 no.2
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• pp.272-278
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• 1999

The primary lymphoma in the lung is very rare. Moot of the primary pulmonary lymphomas, which represent 3-4 % of extra-nodal lymphomas, are low-grade B-cell lymphoma. The low-grade B-cell lymphomas progress slowly and the prognosis of these are more favorable than that of the nodal lymphomas. However, high-grade forms progress rapidly with more severe course. The diagnosis of primary pulmonary lymphomas generally relies on the histopathologic findings of lung specimens obtained by surgical excision of the lesions or open-lung biopsy. Recently, less aggressive biopsies(transbronchial, transthoracic) and/or immunocyto-chemical, immunochemical and gene rearrangement studies on materials obtained by bronchoalveolar lavage have been used occasionally. The treatment of the primary pulmonary lymphomas has not been precisely codified. Several clinical data suggest that limited surgery or non-aggressive chemotherapy can provide long-term survival in patients with such slowly developing neoplasm, and demonstrated the need for the development of noninvasive diagnootic methods. In this study, we report a case of high-grade B-cell lymphoma of the lung which was treated with combination chemotherapy.

• Applied Chemistry for Engineering
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• v.26 no.6
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• pp.737-742
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• 2015

An environmentally favorable solid oxidizer, guanidine dinitramide ($H_2C(NH_2)NH_2N(NO_2)_2$), with high purity and synthesis yield was prepared using guanidine carbonate ($NH_2C(=NH)NH_2{\cdot}1/2H_2CO_3$). Two different crystalline forms (${\alpha}$-form and ${\beta}$-form) were obtained depending on the solvent used and synthesis process. Despite of the same chemical composition, Raman-IR and TGA-DSC revealed that different structures existed between them. In particular, the thermal analysis showed the exothermic temperature of ${\alpha}$-form at $155.7^{\circ}C$ while $191.6^{\circ}C$ for ${\beta}$-form. The caloric value of ${\alpha}$-form was 536.4 J/g which was 2.5 times larger than that of ${\beta}$-form, 1310 J/g. In addition, ${\alpha}$-form was steeply decomposed with one-step variation, but ${\beta}$-form followed a two-step thermal decomposition pattern.

• Proceedings of the Korean Society of Crop Science Conference
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• 2017.06a
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• pp.233-233
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• 2017

Algal communities are important to maintain the aquatic ecosystems function. Algae have short life cycles, they respond quickly to environmental change and their diversity and density can indicate and the quality of their habitat. The bloom forms before the rice seedings have emerged, it may present a physical barrier that prevents the seedlings from penetrating the floodwater. Wind may also move the algal bloom, pushing the young plants beneath the surface. Another harmful action develops when the water dries up and the algae form a layer at the bottom of the field. The layer envelops the seedlings, which are not yet deeply rooted, and drag them to the surface when the water is let in again. Soil utilization pattern can be the mail facter affecting soil physico-chemical properties, especially in soil phosphorus (P). Solid content of the algae culture solution increased with the increase in the nitrogen rather the phosphors concentration. Phosphoric acid was treated with conventional treatments (100-0%, before transplanting time-tillering stage), 50-50%, 0-100%, and un-treated. The herbicide was treated on the 7 DAT (day after transplanting). Green algae samples were collected 20 DAT. Total phosphoric acid was the highest at 0.06 in 50-50% treatment in 20 DAT. The amount of green algae was about twice (9.8 mg/20ml) that of un-treated. Total number of green algae was 54 species(Green algae 35 species, Euglena 9 species, Stone wheel 10 species). Among the phosphoric acid treatment methods, the number of occurrences of green algae were the highest with 39 species in 0-100%, followed by 50-50%, 28 species, conventional treatments, 22 species, non-treatment, 18 species, respectively. Rice Yield was not significantly different by phosphoric treatment time, but slightly higher than un-treated. The maximal algal biomass was observed about 2weeks or 1 month after transplanting; the subsequent decrease of the biomass was related to the consumption by grazers and to a deficient light under the rice canopy. Maximal algal growth was observed just before tillering. To estimate the suitable method of phosphorus application in puddled-soil drill seeding of rice, available phosphorus appearance of algal water bloom, and rice yield were investigated in paddy soil of rice-barley double cropping system.

• Journal of Energy Engineering
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• v.25 no.4
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• pp.13-29
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• 2016

In this study, we analyzed the causes of major faults in the biogas plant through the case of gas engine failure when cogenerating electricity and heat using biogas as a fuel in the actual sewage treatment plant and suggested countermeasures. Hydrogen sulfide in the biogas entering the biogas engine and water caused by intermittent malfunction of the water removal system caused intercooler corrosion in the biogas engine. In addition, the siloxane in the biogas forms a silicate compound with silicon dioxide, which causes scratches and wear of the piston surface and the inner wall of the cylinder liner. The substances attached to the combustion chamber and the exhaust system were analyzed to be combined with hydrogen sulfide and other impurities. It is believed that hydrogen sulfide was supplied to the desulfurization plant for a long period of time because of the high content of hydrogen sulfide (more than 50ppm) in the biogas and the hydrogen sulfide was introduced into the engine due to the decrease of the removal efficiency due to the breakthrough point of the activated carbon in the desulfurization plant. In addition, the hydrogen sulfide degrades the function of the activated carbon for siloxane removal of the adsorption column, which is considered to be caused by the introduction of unremoved siloxane waste into the engine, resulting in various types of engine failure. Therefore, hydrogen sulfide, siloxane, and water can be regarded as the main causes of the failure of the biogas engine. Among them, hydrogen sulfide reacts with other materials causing failure and can be regarded as a substance having a great influence on the pretreatment process. As a result, optimization of $H_2S$ removal method seems to be an essential measure for stable operation of the biogas engine.

• Economic and Environmental Geology
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• v.36 no.5
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• pp.349-356
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• 2003

As industrial activities are growing, pollutants found in the contaminated land are getting diverse. Some contaminated areas are subject to mixed wastes containing both organic and inorganic wastes such as hydrocarbon and heavy metals. This study concerns with the influence of the degradation of organic pollutants on the coexisting heavy metals, expecially for As. As mainly exists as two different oxidation state; As(III) and As(V) and the conversion between the two chemical forms may be induced by organic degradation in the soil contaminated by mixed wastes. We operated microcosm in an anaerobic chamber for 60 days, using sandy loam. The soils in the microcosm are artificially contaminated both by tetradecane and As, with different combination of As(III) and As(V); As(III):As(V) 1:1, As(III) only and As(V) only. Although not systematic, ratio of As(III)/As(Total) increase slightly at the later stage of experiment. Considering complicated geochemical reactions involving oxidation/reduction of organic materials, Mn/Fe oxides and As, the findings in the study seem to indicate the degradation of the organics is connected with the As speciation. That is to say, the As(V) can be reduced to As(III) either by direct or indirect influence induced by the organic degradation. Although Fe and Mn are good oxidising agent for the oxidation of As(III) to As(V), organic degradation may have suppressed reductive dissolution of the Fe and Mn oxides, causing the organic pollutants to retard the oxidation of As(III) to As(V) until the organic degradation ceases. The possible influence of organic degradation on the As speciation implies that the As in mixed wastes may be have elevated toxicity and mobility by partial conversion from As(V) to As(III).

• Journal of the Korean Vacuum Society
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• v.6 no.1
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• pp.9-19
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• 1997

The reaction mechanisms of dry cleaning with UV-excited chlorine radical for Zn, Fe and Ti trace contaminants on the Si wafer have been studied by SEM, AFM and XPS analyses in this work. The patterned Zn, Fe and Ti films were deposited on the Si wafer surface by thermal evaporation and changes in the surface morphology after dry cleaning with $Cl_2$and UV/$Cl_2$at $200^{\circ}C$ were studied by optical microscopy and SEM. In addition, changes in the surface roughness of Si wafer with the cleaning was observed by AFM. The chemical bonding states of the Zn, Fe and Ti deposited silicon surface were observed with in-line XPS analysis. Zn and Fe were easily cleaned in the form of volatile zinc-chloride and iron-chloride as verified by the surface morphology changes. Ti which forms involatile oxides was not easily removed at room temperature but was slightly removed by UV/$Cl_2$at elevated temperature of $200^{\circ}C$. It was also found that the surface roughness of the Si wafer increased after $Cl_2$and UV/$Cl_2$cleaning. Therefore, the metallic contaminants on the Si wafer can be easily removed at lower temperature without surface damage by a continuous process using wet cleaning followed by UV/$Cl_2$dry cleaning.