• Applied Chemistry for Engineering
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• v.19 no.1
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• pp.92-97
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• 2008

Selective catalytic reduction (SCR) of NO with ammonia was carried out over the physical mixture of $MnO_2$ and K or Cu-loaded activated carbons (AC) at low temperature. Introduction of oxygen affected positively the reduction of NO. Metal-impregnated AC showed significantly enhanced catalytic activity. Without water, the mixed catalyst of $MnO_2$ and K-loaded AC exhibited the best activity in the reduction of NO at $120^{\circ}C$. On the contrary, the activities of all the catalysts were significantly diminished in the presence of water. The mixed catalyst of $MnO_2$ and Cu-loaded AC treated with nitric acid and heat (1 : 1, w/w) exhibited the better activity for the reduction of NO than each single catalyst in presence of water.

• Analytical Science and Technology
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• v.10 no.4
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• pp.231-239
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• 1997

We developed a procedure that can effectively separate and determine tertiary amines and quaternary ammonium salts in some samples with reverse phase ion-pair high performance chromatography, employing indirect spectrophotometric detection method. Detection and ion-pairing reagents used in this study were benzyl trimethylammonium chloride (BTMACl) and sodium dodecyl sulfate(DDSANa), respectively. Eluting the electrolyte solutions of some commercial electrolytic capacitors with a MeOH(40):water(60) eluent (pH 8.5 adjusted with NH4Cl-NH3 buffer) containing 0.010M DDSANa and 0.004 M BTMACl through Supelco LC-18 or ${\mu}$-Bondapak phenyl column, amines and ammonium salts contained in the sample were successfully separated and determined. Varying the composition, especially the content of quaternary ammonium salts, of electrolyte solutions based on this analysis. we could prepare the low impedance(0.08~0.13) electrolytic capacitors with excellent electrical properties and it was a confirmation that the analysis is favorable.

• Fire Science and Engineering
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• v.30 no.2
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• pp.7-18
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• 2016

This study evaluated the toxicity of the burning gas from the synthetic wood products used in housings or warehouses. The combustion products of five materials, viz. impregnated laminated board, MDF, Douglas fir plywood, core plywood, and Lauan retardant, were analyzed using SEM, FTIR and a Cone Calorimeter. For the Lauan retardant, 256,965 ppm of carbon dioxide ($CO_2$) and 1,475 ppm of sulfur dioxide ($SO_2$) were measured, which are 2.5 times and 3.6 times as high as their lethal concentrations of 100,000 ppm and 400 ppm, respectively. For the impregnated laminated board, 1,569 ppm of nitrogen dioxide ($NO_2$) was measured, which is 6 times as high as its lethal concentration of 250 ppm. For MDF, 795 ppm of ammonia ($NH_3$) was measured, which is higher than its lethal concentration of 750 ppm. As a result, most internal-finishes generated toxic combustion products at levels higher than their lethal concentrations, which underlines the importance of the selection and manufacturing of internal-finish materials.

• Applied Biological Chemistry
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• v.24 no.4
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• pp.238-244
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• 1981

The thin Layer chromatographic determination of ${\alpha}-solanine $ in potato tuber was investigated. The solanine was extracted with methanol-chloroform mixture (2 : 1, v/v) and precipitated as the crude glycoalkaloid by the addition of ammonium hydroxide. The solanine in the crude precipitate was separated by TLC using a solvent system of 1% $NH_4OH-absolute$ ethanol-chloroform (1:2:2, v/v). The purity of ${\alpha}-solanine $ was confirmed by infrared spectrophotometry. The ${\alpha}-solanine $ separated by TLC was determined at the wavelength of 310nm after coloration with concentrated sulfuric acid-1% paraformaldehyde, with the molar absorptivity of 2,090.

• Proceedings of the Materials Research Society of Korea Conference
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• 2003.03a
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• pp.134-134
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• 2003

SnO$_2$를 모물질로 하는 가스센서는 n형 산화물 반도체로서 공기중의 산소의 흡탈착 및 전자의 수수에 의해 전기전도도의 변화로 특정 가스를 감지한다. 지금까지 반도체식 가스센서의 모물질로 가장 많이 연구되어 왔지만 아직도 선택성, 안정성 등 여러 가지 문제를 안고 있다. 그리고 개선방안으로 귀금속 촉매의 첨가 및 입자의 크기의 조절 등이 흔히 연구되어 왔다. 따라서 본 연구에서는 순수한 SnO$_2$ 를 이용하여 소결 온도 및 입자 크기에 의한 영향을 CO가스 및 수분에 대한 감도, 반응 시간을 통해 알아보았다. 수열 합성 및 침전 법으로 나노 크기의 SnO$_2$ 분말을 합성하여 스크린 인쇄법으로 후막 가스센서를 제조하였다 침전법에서 SnCl$_4$에 암모니아수로 pH=10.5로 적정하여 SnO$_2$ 분말을 얻었다. 그리고 입자 크기를 조절하기 위해 수열 합성 시 autoclave 내의 수열처리 온도를 100, 150, 20$0^{\circ}C$로 조절하여 SnO$_2$ 분말을 제조하고 입자 크기와 성분분석을 위해 XRD, SEM, TEM, BET 측정을 하였다. 그 결과 침전법으로 제조한 입자의 크기는 20nm 정도였으며 수열 처리한 SnO$_2$ 입자는 10nm이하의 미세한 입자를 얻을 수 있었다. 수열 합성 시 온도가 높아질수록 더 작은 입자 크기를 얻을 수 있었고 600, 7()0, 80$0^{\circ}C$ 열처리 후 입자성장이 침전법에 의한 SnO$_2$ 분말보다 더 작게 일어났다. 이렇게 제조한 나노크기의 SnO$_2$ 분말을 이용하여 습도 및 CO 가스에 대한 그 특실을 평가하였다. CO 20ppm에 대하여 40%정도의 감도를 보였으며 입자가 작아질수록 높은 감도를 보이는 것을 확인 할 수 있었다. 반면 CO 가스와 반응 후 회복 시 입자 의기가 작아질수록 회복이 늦어짐을 알 수 있었다. 그리고 15$0^{\circ}C$에서 습도에 대한 반응 후 회복시간을 조사해보니 같은 결과를 얻을 수 있었다. 이것은 입자 필기가 작아질수록 많은 흡착 사이트를 제공함으로써 높은 감도를 가지지만 반면 다량의 흡착된 가스들이 탈착 하는데 더 많은 시간이 소요되었기 때문이다.

• Applied Biological Chemistry
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• v.49 no.1
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• pp.7-14
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• 2006

This study was carried out to examine the quality characteristics of soybean pastes made of Meju with mold-producing pretense isolated from traditional Meju. The changes in moisture content, enzyme activity (amylase, protease, lipase), reducing sugar, amino-type nitrogen contents and anti-oxidant activity were investigated during the aging period. The moisture contents decreased gradually with time. Amylase activity decreased during the aging period while pretense and lipase activities increased until 30-45 days of aging, but decreased thereafter, Especially pretense activity in soybean paste with mold was greater than that in the control. Amino-type nitrogen and ammoniacal nitrogen contents increased, but reducing sugar contents decreased with time. Amino-type nitrogen contents were greater in soybean paste made of Meju with isolated mold than those in the control. Antioxidative activity was also confirmed in soybean paste.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.8
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• pp.2935-2941
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• 2010

This study used 3 kinds of experimental toothpaste with different contents(0%, 1.1%,2.2% of SLS. A total of 150 young adults in their 20's without any systemic disease were recruited for the study. These 150 subjects were subdivided into three groups(each having 50 subjects) according to the results of preliminary oral examination.After 4 weeks application of the three groups of toothpaste, Group C showed the highest halitosis index, followed by Groups A and B which had similar halitosis indices. Both oral sulfur compound and aerobic sulfur compound were measured at high content possibly because higher SLS content which is associated with the lower salivary flow rate is causing the xerostomia. SLS content was correlated with oral sulfur compound (r=0.412) and aerobic sulfur compound (r=0.285).

• Journal of the Korea Academia-Industrial cooperation Society
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• v.8 no.2
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• pp.372-379
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• 2007

The converter slag can be used to remove phosphate ion into the form of solid state from the wastewater. This research aims to evaluate the change of pH, alkalinity, leaching of positive ion in the wastewater and the removal of phosphate from the initial condition of wastewater. The change of pH was abruptly increased upto pH 11 for the initial condition of pH from 7.0 to 8.5 fer 0.5 unit of pH. The alkalinity was steadily increased from 10 hours of reaction time not same as pH increase. The removal of phosphate was very effective till 10 hours of reaction then it was slow after that time. The positive ion, magnesium ion was leached from the concentration of 2.0 mg/L to 4.3mg/L at the reaction time of 27 hours and 36 hours. Therefore, converter slag can be used to remove the phosphate in the form of Struvite from the wastewater.

• Journal of Aquaculture
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• v.6 no.3
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• pp.187-197
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• 1993

Studies related to water quality in catfish ponds were conducted on commercial catfish production ponds and compared with its receiving streams' water quality in central and west-central Alabama. The ponds were stocked with 10,000 fish/ha. The ponds were aerated nightly (0000-0600 hrs). Fish were fed to satiation at about the same time, six-days a week. In order to assess the pollutional strength of effluents from commercial channel catfish ponds, water samples were collected during each calender season from fall 1990 through summer 1991, and selected water quality variables were monitored. Mean values for water temperature, dissolved oxygen concentration, pH, settleable solids, total suspended soilds, volatile solids, total phosphorus, soluble reactive phosphate, biochemical oxygen demand, total ammonia nitrogen, nitrite, nitrate, and total Kjeldahl nitrogen were basically the same (P> 0.05) between samples taken from the surface and near the bottom. Concentrations of most water quality variables of catfish ponds were higher than those of receiving streams, and especially it had much higher average concentrations of nitrogen and phosphorus than streams.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.2 no.2
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• pp.110-116
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• 1997

Changes of fish species composition were analyzed using seasonal samples collected from Lake Shihwa and adjacent coastal water from October 1995 to August 1996. Pelagic clupeids, Cynoglossus joyneri and Johnius belengerii predominated in abundance in the adjacent coastal water. In the lake, clupeids, gobies and freshwater Carassius carassius were collected in autumn. The clupeids, unable to overwinter in the open water, disappeared after winter. The gobies and C. carassius were also disappeared in spring except a few number of Acanthogobius hasta. A large number of Tridentiger trigonocephalus and Eleotris oxycephala were collected in summer, supposed to move into the lake during the exchange of water in lake and sea water. However, they were all died in the middle of August. The concentration of ammonium-nitrogen was higher than 2 mg/l, which was higher than 50% lethal concentraton in other fishes. Increase in temperature and pH in spring may elevate the toxicity of ammonium to fish. We discussed the effect of the other factors of the polluted water in the lake on the disappearance of fish.