• Korean Journal of Materials Research
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• v.4 no.6
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• pp.611-619
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• 1994

The formation of , $\beta$-quartz solid solution in the $LiO_2-Al_2O_3-SiO_2$glasses containing $TiO_{2}$ and $ZrO_{2}$ as nucleating agents was investigated for various temperatures and times. Linear thermal expansion coefficients of base glasses and crystallized glasses were $45\sim 55 \times 10^{-7} \textrm{cm}/^{\circ}C$ and $ -8\sim +8 \times 10^{-7}\textrm{cm}/^{\circ}C$ ($25^{\circ}C \sim 525^{\circ}C$), respectively. The crystal phase formed by heat-treatment below $900^{\circ}C$was , $\beta$--quartz solid solution, and the crystal sizes were less than 0.21m. On the other hand, the crystal size of the base glasses containing 3.5 wt% MgO is relatively uniform and is independent with temperature. The specimen containing 3.5 wt% ZnO shows a minimum crystal size(O.l8$\mu \textrm{m}$), and it strongly depends on temperature of heat-treatment.

• Korean Journal of Materials Research
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• v.30 no.10
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• pp.566-572
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• 2020

In the recent years, thin film solar cells (TFSCs) have emerged as a viable replacement for crystalline silicon solar cells and offer a variety of choices, particularly in terms of synthesis processes and substrates (rigid or flexible, metal or insulator). Among the thin-film absorber materials, SnS has great potential for the manufacturing of low-cost TFSCs due to its suitable optical and electrical properties, non-toxic nature, and earth abundancy. However, the efficiency of SnS-based solar cells is found to be in the range of 1 ~ 4 % and remains far below those of CdTe-, CIGS-, and CZTSSe-based TFSCs. Aside from the improvement in the physical properties of absorber layer, enormous efforts have been focused on the development of suitable buffer layer for SnS-based solar cells. Herein, we investigate the device performance of SnS-based TFSCs by introducing double buffer layers, in which CdS is applied as first buffer layer and ZnMgO films is employed as second buffer layer. The effect of the composition ratio (Mg/(Mg+Zn)) of RF sputtered ZnMgO films on the device performance is studied. The structural and optical properties of ZnMgO films with various Mg/(Mg+Zn) ratios are also analyzed systemically. The fabricated SnS-based TFSCs with device structure of SLG/Mo/SnS/CdS/ZnMgO/AZO/Al exhibit a highest cell efficiency of 1.84 % along with open-circuit voltage of 0.302 V, short-circuit current density of 13.55 mA cm^-2, and fill factor of 0.45 with an optimum Mg/(Mg + Zn) ratio of 0.02.

• Bulletin of the Korean Chemical Society
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• v.32 no.9
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• pp.3281-3289
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• 2011

The materials composed of the 3d series transition metals are introduced into the hydrocarbon steam-reforming reaction in order to enhance the $H_2$ production and abruptly depress the catalytic deactivation resulting from the strong sintering between the Ni component and the ${\gamma}-Al_2O_3$ support. The conventional impregnation method is used to synthesize the Ni/3d series metal/${\gamma}-Al_2O_3$ materials through the sequentially loading Ni source and the 3d series metal (Ti, V, Cr, Mn, Fe, Co, Cu, and Zn) sources onto the ${\gamma}-Al_2O_3$ support. The Mnloaded material exhibits a significantly higher reforming reactivity than the conventional Ni/${\gamma}-Al_2O_3$ and the other Ni/3d series metal/${\gamma}-Al_2O_3$ materials. Particularly the addition of Mn selectively improves the $H_2$ product selectivity by eliminating the formation of $CH_4$ and CO. The $H_2$ production is maximized at a value of 95% over Ni(0.3)/Mn(0.3)/${\gamma}-Al_2O_4$(1.0) with a butane conversion of 100% above $750^{\circ}C$ for up to 55 h.

• Journal of the East Asian Society of Dietary Life
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• v.13 no.1
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• pp.56-63
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• 2003

The dough fermentation and the quality of bread prepared with different kinds of water such as distilled water, tap water and diluted hot spring water(SW) from Gyungsan Sipan hot spring were investigated. Content of total soluble solid in the hot spring water was 8,765 ppm and contents of Na, Ca, Mg and K as major elements was 2,296, 287, 65 and 8 ppm, respectively. Content of Fe, Cu, Co, F, Zn, Al, S, Mo, Se and Si as minor elements was in the range of 0.002~5.2 ppm. The pH(6.95~7.68) of the dough prepared with diluted hot spring water(I, 55 times; II, 4 times; III, 2 times) was higher than that of distilled water. The dough volume after the 1st fermentation was expecially lower in the III, but the volume of the dough prepared with III adjusted pH to 5.5 was higher than that of the control. The hardness and the strength were higher than those of the control, but the scores were love. than those of the control in case of pH adjustment(pH 5.5). The cohesiveness was also lower than that of the control in the bread with diluted hot spring water. Softness and stickiness of the bread(III) were hisher than those of the control. But overall acceptability was the highest in the II.

• Korean Journal of Microbiology
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• v.47 no.3
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• pp.194-199
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• 2011

An alkalophilic bacterium producing alkaline protease was isolated from waste water and solar saltern sample and identified as Bacillus pseudofirmus HS-54 based on morphological, biochemical characteristics as well as 16S-rRNA gene sequencing. The HS-54 protease was purified to homogeneity using ammonium sulfate precipitation, DEAE cellulose column chromatography, and sephadex G-100 gel filtration with a 4.0 purification fold. The molecular mass of the purified enzyme was estimated by SDS-PAGE to be 27 kDa. The optimal pH and temperature for the purified protease activity were 10.0 and $50^{\circ}C$, respectively. The purified enzyme was relatively stable at the pH range of 6.0-11.0 and at the temperature below $50^{\circ}C$. This enzyme was activated by $Ca^{2+}$ and $Mg^{2+}$ and inhibited by $Hg^{2+}$, $Cu^{2+}$, $Zn^{2+}$, $Al^{3+}$, $Ag^{2+}$. And this enzyme was strongly inhibited by PMSF, suggesting that it belongs to the serine protease superfamily.

• Journal of Korean Society on Water Environment
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• v.28 no.2
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• pp.277-284
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• 2012

This study developed a new ceramics in which natural zeolite was mixed and calcined with industrial by-product such as converter slag, red mud, and fly ash and evaluated the feasibility of the ceramics for removal of heavy metals in acid wastewater. The removal rate of heavy metal by ceramics increased in the order of ZS (zeolite and slag) > ZR (zeolite and red mud) > ZF (zeolite and fly ash) ceramics. The alkalinity increment and coherence of ceramics were increased in the order of ZS > ZR > ZF ceramics. The mixing ratio of natural zeolite to industrial by-product for maximum removal efficiency of heavy metal was 1:1 for ZS ceramics and 1:3 for ZR and ZF ceramics. The order of removal efficiency of heavy metal was observed to be ZS > ZR > ZF ceramics under the mixing ratio of 1:1 for ZS ceramics and 1:3 for ZR and ZF ceramics. The removal efficiency of heavy metal by ZS ceramics with 1:1 mixing ratio was Al 100%, Cd 54.6%, Cr 99.9%, Cu 98.7%, Fe 99.9%, Mn 42.2%, Ni 59.9%, Pb 99.8%, Zn 87.6%, respectively. In addition, the removal capacity of heavy metal by ZS ceramics was observed to be Al 2.01 mM/g, Cd 0.27 mM/g, Cr 1.02 mM/g, Cu 0.83 mM/g, Fe 0.95 mM/g, Mn 0.41 mM/g, Ni 0.55 mM/g, Pb 0.25 mM/g, Zn 0.70 mM/g, respectively. The comparative evaluation in the light of removal capacity, alkalinity increment, and coherence of ceramics showed the ZS ceramics had higher feasibility as a media than others for removal of heavy metals in acid wastewater.

• Economic and Environmental Geology
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• v.30 no.3
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• pp.209-222
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• 1997

The Hoenam area, up the Taecheong lake, composed mainly of low grade coal-bearing metapelites within the Ogcheon Supergroup. These coal formations are developed discontinuously several hundred meters and swelling from 10 to 300 cm along the host metapelites. Although the formations have been mined for coal, but already mined out, and the formations were higher content (mean value of 42 samples) of environmental toxic elements as As (13 ppm). Ba (1.81 wt. %), Cd (2 ppm), Cr (188 ppm), Cu (87 ppm), Mo (214 ppm), Pb (25 ppm), Sb (3 ppm), Se (12 ppm), U (55 ppm), V (2124 ppm) and Zn (234 ppm) than the host metapelites and the NASC. The Al, Ti, Mg, K and Na contents in stream sediments derived from the Hando and Bugook mine area were highly concentrations than the samples from the Samseongjeil mine area. The mean value (wt. %) of Fe (10.07), Mn (0.15), Ca (0.84), P (0.18) and Ba (0.77) influenced by the Samseongjeil mine were higher than the other mine drainage sediments. The mean content (ppm) of environmental toxic elements in drainage sediments from the Samseongjeil mine were taken As (2083), Cu (447), Mo (202), Ni (720), Pb (42), U (250), V (1070) and Zn (2632), which are extremely high concentrations against NASC and EPA. Characteristics of elemental behavior and dispersion of the all toxic elements are the same as increased with increasing U, V, and Cu. Rare earth elements in the sediments are enriched with LREE (La, Ce and Nd) from the drainage on strong concentration of toxic elements. The pH of stream water is neutral, but pH of the sediments ranged from 4.92 to 6.93 (mean 6.22), those are slightly acid in the Hando mine area. Major elements in the host rocks at the Hoenam area are mostly depleted especially Ca, excepting Ti and Ba, normalized with NASC. The sediments were highly enriched of Ti, Fe, Mg, Mn and Ba, but depleted of Al, K, Ca, Na and P on the basis of host rocks and NASC. Minor and environmental toxic elements in the host rocks were strongly enriched all elements (As, Cd, Mo, Se, D, V and Zn), excepting Co, Ni and Sr. Enrichment index (mean value) about toxic elements (As, Cr, Cu, Fe, Ni, Pb and Zn) of the sediments in this area have taken 41.35 (Hando mine drainage; 2.73, Samseongjeil mine drainage; 113.14 and Bugook mine drainage; 8.19), those are seriously contaminated by environmental toxic elements.

• Proceedings of the Korean Society of Postharvest Science and Technology of Agricultural Products Conference
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• 2003.04a
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• pp.121.1-121
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• 2003

증류수, 수도수, 온천수(경산 사이판 온천) 희석액 (55배 희석; I, 4배 희석; II, 2배희석; III을 사용한 반죽의 발효와 빵의 품질에 미치는 영향을 조사하였다. 경산사이판 온천수는 총고형물이 8,765 ppm 이였으며 주요 무기질로는 Na가 2296 ppm, Ca가 287 ppm, Mg와 K가 각각 65 및 8 ppm을 함유하였다. Fe, Cu, Co, F. Zn Al, S, Mo, Se 및 Si 등이 0.002~5.2 ppm을 함유하였다. 온천수를 사용한 반죽의 pH는 6.95~7.68로 증류수의 6.40보다 높았다. 반죽부피는 온천수의 농도가 높아짐에 따라 감소하였다. pH를 5.5로 조정한 온천수를 사용한 반죽의 부피는 대조구 보다 오히려 높았다. 온천수를 사용한 빵의 경도 (hardness)와 신장성(strength)는 대조구 보다 높았으나 pH를 조정한 온천수의 경우는 낮았다. 점착성은 경도 및 신장성과는 역으로 희석 온천수에서 낮았다. pH 조정 없이 구운 빵의 부드러운 정도는 4배로 희석한 온천수가 증류수 및 55배, 2배 희석 온천수보다 높았다. 쫄깃한 맛도 온천수가 대조구에 비하여 높았으며 종합적인 기호도는 4배 희석 온천수가 가장 좋았다.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.1 no.1
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• pp.71-78
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• 2002

Since the early 1980's the use of zinc-aluminum alloy-coated steel sheet(Galvalume) for vehicular corrosion protection has increased drastically. It is consisting of 55%Al-43.4% Zn-1.6%Si. Galvalume has a good corrosion resistance, heat reflectivity and shiny appearance, which has a dendritic structure of alloy layer. It has a good corrosion resistance due to dendritic structure. But, this also has a weak point against moisture during long period of transportation as sheeted and or coiled without any relation of chromating on the surface of steel sheet or not because of high humidity and temperature. Here, We studied the corrosion mechanism by the moisture.

• Journal of Korean Society of Environmental Engineers
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• v.34 no.4
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• pp.239-246
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• 2012

This study was performed to investigate the removal characteristics and mechanism of heavy metals using pellet-type ceramics(ZS ceramics), in which natural zeolite was mixed and calcined with converter slag. The optimal calcination temperature range was measured to be $600{\sim}800^{\circ}C$. The calcination time had little effect on the removal of heavy metal in acid wastewater. The adequate dose of ceramics was shown to be 2~5% for removal of heavy metals in acid wastewater. The maximum removal capacity of ZS ceramics for heavy metals were observed to be Al 84.7 mg/g, Cd 37.3 mg/g, Cr 81.7 mg/g, Cu 55.6 mg/g, Fe 57.2 mg/g, Mn 32.1 mg/g, Ni 38.0 mg/g, Pb 71.6 mg/g, Zn 46.3 mg/g. The pH played a pivotal role in the removal of heavy metals by ZS ceramics. The analysis results of mechanism exhibited that the ZS ceramics could act as a multi-functional ceramics for removal of heavy metals in acid wastewater by adsorption, ion-exchange, or precipitation.