• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.4
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• pp.596-601
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• 2020

Silicon carbide is considered a potentially useful material for high-temperature electronic devices because of its large band gap energy and p-type or n-type conduction that can be controlled by impurity doping. Accordingly, the thermoelectric properties of -SiC powder prepared by refined diatomite were investigated for high value-added applications of natural diatomite. -SiC powder was synthesized by a carbothermal reduction of the SiO₂ in refined diatomite using carbon black. An acid-treatment process was then performed to eliminate the remaining impurities (Fe, Ca, etc.). n-Type semiconductors were fabricated by sintering the pressed powder at 2000℃ for 1~5h in an N2 atmosphere. The electrical conductivity increased with increasing sintering time, which might be due to an increase in carrier concentration and improvement in grain-to-grain connectivity. The carrier compensation effect caused by the remaining acceptor impurities (Al, etc.) in the obtained -SiC had a deleterious influence on the electrical conductivity. The absolute value of the Seebeck coefficient increased with increasing sintering time, which might be due to a decrease in the stacking fault density accompanied by grain or crystallite growth. On the other hand, the power factor, which reflects the thermoelectric conversion efficiency of the present work, was slightly lower than that of the porous SiC semiconductors fabricated by conventional high-purity -SiC powder, it can be stated that the thermoelectric properties could be improved further by precise control of an acid-treatment process.

• Proceedings of the Korea Society for Energy Engineering kosee Conference
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• 1999.05a
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• pp.185-191
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• 1999

An air-conditioning system based on the chemical heat storage principle was considered. $H_2O$ was chosen as the reaction gas and the working fluid as well. Na$_2$S, CaCl$_2$, MnCl$_2$, BaCl$_2$, MgCl$_2$, Fe$_2$(SO$_4$)$_3$ and MnSO$_4$ were tested as the solid reactants by using Cahn pressure balance. Na$_2$S was superior to other salts in respect of high capability of absorption of water gas, 5 moles of $H_2O$ per unit mole of Na$_2$S, and adequate temperature of adsorption, $65^{\circ}C$ at 7torr, and of desorption, 13$0^{\circ}C$ at 76torr. Clausius-Clapeyron diagram of Na$_2$S was obtained via adsorption experiments at several vapor pressures of water gas. To enhance heat and mass transfer characteristics, usually below 1W/m K, of the reactor bed of general adsorption systems, expanded graphite block was adapted as the support of Na$_2$S salt. Expanded graphite blocks had thermal conductivity values of 20~80W/mK with respect to 100~400kg/㎥ of block bulk density. Permeability values of expanded graphite blocks were 10$^{-13}$ ~ 10$^{-14}$ $m^2$ with respect to 100~300kg/㎥ of block bulk density showing highly decreasing values of permeability, below 10$^{-l4}$$m^2$, in the range of above 150kg/㎥ of block bulk density.y.

• Korean Journal of Food Science and Technology
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• v.23 no.3
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• pp.375-378
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• 1991

Bangah (Agastache rugosa O. Kuntze), one of the wild plant grown in Korea and used for deodorizing some of the fish foods because it's strong and unique flavor, was determined for chemical composition in leaf, flower and stem. The highest protein content of 14.7% was found in leaf and lipids was in the range of $5.25{\sim}7.74%$. Total sugar content in leaf and flower were 27.53% and 14.86%, reducing sugar content were 11.80% and 2.75%, respectively. Fifteen fatty acids in bangah were identified and the major fatty acids were linolenic, palmitic, lauric and linoleic acids. Seventeen total amino acids were determined in leaf and flower. Glutamic acid, aspartic acid and leucine were high in each portion. The major free amino acids were histidine, serine, proline and glutamic acid. Most of minerals were high in leaf and flower than those in stem of bangah except for Ca and Fe. Especially K was higher in leaf and flower than stem by 4 times.

• Proceedings of the Korean Society of Organic Agriculture Conference
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• 2009.12a
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• pp.308-308
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• 2009

유기농액비 자가제조 방법의 표준화를 위해 농가 현황조사를 통해 유기농액비 제조방법을 분류하고 제조 시기별 성분함량 변동상을 분석하였다. 조사대상 액비는 경기 9, 강원 5, 충북, 1, 충남 20, 전남 6, 경북 5, 경남 8 등 총 54종이었다. 자가제조 유기농액비에 사용된 재료는 감, 매실, 복숭아, 사과, 참다래, 토마토, 파프리카, 양파, 파, 인삼, 미나리, 민들레, 쇠비름, 쑥, 익모초, 산야초, 황기, 환삼덩굴, 으름열매, 은행과피, 배 어린 열매, 감껍질, 깻묵, 들깨대, 물미역, 쌀뜨물, 쌀겨, 꽁치, 바다생선 (잡어), 불가사리, 생선부산물(내장, 뼈 등), 액젓부산물(해산물의 뼈가 많이 함유된 물질), 동물뼈(돼지, 닭 등), 골분, 혈분, 천매암, 천일염, 계란껍질, 조개껍질, 게껍질, 새우껍질, 굴껍질, 농가부산물, 음식부산물, 구아노, 들깨 대 숯, 참깨 대 숯 등이었다. 제조방법은 기본재료+물, 기본재료+물+미생물, 기본재료+당밀, 기본재료+당밀+미생물, 기본재료+흑설탕, 기본재료+흑설탕+미생물 등이었다. 유기농액비의 화학적 특성은 다양하였으며, 혈분을 주 원료로 한 유기농액비의 화학성변화는 시간의 경과함에 따라 pH는 4.99에서 3.85로 낮아졌지만, EC, T-C, T-N, $P_2O_5$, $K_2O$, CaO, MgO, $Na_2O$, Fe, Mn, Zn 등은 높아졌다.

• Korean Journal of Soil Science and Fertilizer
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• v.32 no.2
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• pp.123-131
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• 1999

To get the basic information for the improvement of the optimum levels of upland soil fertility and fertilizer application, the soil samples in two hundred fifteen site were collected from the major condiment vegetable cultivation areas such as red pepper, garlic and onion fields. Physico-chemical properties of the soil samples were investigated. Soil texture distribution of soil samples in red pepper, garlic and onion cultivation areas was in order of loam (L), sandy loam (SL), silt loam (SiL) and clay loam (CL) (35.4, 31.6, 14.9 and 7.0%, respectively). The average pH of soil in garlic and onion cultivation areas were over pH 6.0, whereas in red pepper was under pH 5.5. The frequency distribution of soil pH in total sampling sites were 58.7% in under pH 6.0 and 21.4% in below pH 5.0, in contrast to 10.3% in over pH 7.0. The organic matter contents were in the range of $20{\sim}30g\;kg^{-1}$, and the onion field soils was a little higher than those in red pepper or garlic. The available phosphate contents were in the range of $719{\sim}746mg\;kg^{-1}$ and were not different among in red pepper, garlic and onion. The frequency distribution of available phosphate in total sampling sites were found 62.8% of above $600mg\;kg^{-1}$, which was over the standard level for upland soil improvement, and then 22.3% was exceeded $1,000mg\;kg^{-1}$, especially. In the exchangeable cations, the K and Ca contents in garlic (1.27 and $9.11cmol\;kg^{-1}$) and onion (1.20 and $8.39cmol\;kg^{-1}$) were higher than in red pepper (0.96 and $5.87cmol\;kg^{-1}$), respectively. The Mg contents in garlic field soils ($2.17cmol\;kg^{-1}$) were higher than those in red pepper and onion (1.51 and $1.80cmol\;kg^{-1}$). This exchangeable K, Ca and Mg contents were higher than the standard level for upland soil improvement. The contents of microelement were ranged in $54.3{\sim}60.1mg\;kg^{-1}$ for Fe, $31.3{\sim}42.3mg\;kg^{-1}$ for Mn, $1.7{\sim}2.3mg\;kg^{-1}$ for Cu and $4.8{\sim}5.5mg\;kg^{-1}$ for Zn, respectively.

• Korean Journal of Medicinal Crop Science
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• v.22 no.1
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• pp.32-37
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• 2014

To study the cause of physiological disorder in leaf of ginseng cultivated at paddy soil, the degree of brown-colored symptom (BCS) and the contents of inorganic matter in leaf were investigated by irrigating the solution of ferric and ferrous iron of 0.1 ~ 2.0%, and citric acid of 1.0 ~ 4.0% on bed soil, respectively. Ratio of BCS by variety was as high as 85.0% in Yoenpoong, while it was as low as 5.4%, 7.5% in Chunpoong and Hwangsook, respectively. The contents of inorganic matter of leaf in Yoenpoong were lower in $P_2O_5$, Ca, and Mg, while it were higher in K, Fe, and Mn than other variety. Iron solution caused BCS more distinctly when each ferric and ferrous iron were dissolved with 1.0% citric acid than when each iron was dissolved without citric acid. Ferric iron caused BCS more effectively than ferrous iron. BCS occurred in 4.0% citric acid was as same as 2.0% ferric iron mixed with 1.0% citric acid. Low $P_2O_5$ and high Fe content in leaf appeared in both of artificial and natural symptoms. We concluded that excessive Fe uptake caused BCS to leaf because the solubility of iron was increased in condition of low soil pH.

• Clean Technology
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• v.19 no.4
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• pp.453-458
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• 2013

Fly ash has capacity to oxidize or adsorb mercury in a flue gas. Mercury oxidation and adsorption efficiencies of fly ash vary depending on the properties of fly ash. This study was designed to understand reaction characteristics of mercury with fly ash components. The fly ash components were tested to determine their oxidation and adsorption capabilities for elemental mercury and oxidized mercury. A sample was synthesized with fly ash components and tested. The test results were compared with those of the fly ash sample obtained from a coal-fired power plant. $Fe_2O_3$, CuO and carbon black showed higher oxidation or adsorption efficiency for elemental mercury while CaO, MgO, CuO and carbon black showed higher adsorption efficiency for mercury chloride. In addition, the synthesized sample showed comparable mercury oxidation and adsorption efficiencies to the fly ash sample.

• Journal of the Mineralogical Society of Korea
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• v.21 no.4
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• pp.415-423
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• 2008

Earth outer core is composed of iron mainly with some diluent elements, which account for the observed ca. 10% density deficit compared to the pure iron. Among candidates as the light diluents, hydrogen and oxygen were selected, and the thermodynamic stability of the following reaction was calculated; hematite + hydrogen $\to$ goethite + iron. At ambient conditions, Gibb's free energy of this reaction is 12.62 kJ/mol. On increasing pressure at room temperature, it decreases to zero at 0.068 GPa. This energy decreases at constant rate down to 200 GPa, which shows -208.26 kJ/mol at that pressure. From these results, this chemical reaction prefers the reduction environment forming the iron element and iron oxyhydroxide, so possible presence of iron oxyhydroxide with iron at proto-core can not be ruled out.

• Journal of the Korean Recycled Construction Resources Institute
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• v.9 no.2
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• pp.152-160
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• 2021

Converter steel slag(BOF slag) is a vast amount of solid waste generated in the steelmaking process which has very low utilization rate in Korea. Due to the presence of free CaO which can derive bad volume stability in BOF slag, it usually land filled. For recycling BOF and identify its applicability as fine aggregate, this study investigates the fundamental characteristics of mortar with cement replaced ferronickel slag(FNS), which has the potential to be used as a binder. The results suggest that the mineral phases of BOF slag mainly include larnite(CaSiO₄), mayenite(Ca₁₂Al₁₄O₃₃) and wuestite(FeO) while olivine crystallines are shown in FNS. The results of flow and setting time reveals that the flowability and process of hardening increased when the amount of FNS and BOF slag incorporated was increased. The length change shows that the amount of change in the length of the mortar was almost constant regardless of mix proportion while compressive strength was reduced. Micro structure test results revealed that FNS or/and BOF slag mix took a long time to react in the cement matrix to form a complete hydration products. To achieve the efficient utilization of B OF slag as construction materials, proper replacement rate is necessary.

• BMB Reports
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• v.28 no.2
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• pp.170-176
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• 1995

Rhodanese from mouse liver was purified to near homogeneity by ammonium sulfate precipitation, CM-Sephadex ion exchange, hydroxyapatite and Sephacryl S-200-HR gel filtration chromatographies with a purification of 776 folds. The molecular weight was determined by Sephadex G-150 gel filtration and found to be 34.8 KDa. SOS-PAGE showed molecular weight 34 KDa and two identical subunits splitting by aging for 3 weeks at $-70^{\circ}C$ the molecular weight of which was 17 KDa. The optimal pH of enzyme activity was 9.4 and the pI value of the enzyme was 6.6. Rhodanese showed the optimal reaction temperature of $25^{\circ}C$ and near linear increasing pattern until 10 min. incubation. $K_m$ values of rhodanese for KCN and $Na_{2}S_{2}O_{3}$ as substrates were 12.5 mM and 8.3 mM, respectively. Rhodanese activity was inhibited by more than 70% at a concentration of 100 ${\mu}M$ of $Ni^{2+}$, $Zn^{2+}$, $Cd^{2+}$, $Hg^{2+}$ and $Cu^{2+}$. Other metal ions, such as $Mn^{2+}$, $Mg^{2-}$, $Ca^{2+}$, and $Fe^{2+}$ showed no effect on rhodanese activity.