• Environmental Engineering Research
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• 제10권1호
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• pp.22-30
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• 2005

Nitrite accumulation is not unusual in batch processes such as sequencing batch reactor (SBR) with high-strength of ammonium or nitrate wastewaters. A possible mechanism of nitrite inhibition on Acinetobacter was depicted in a biochemical model, which the protonated species, nitrous acid form of nitrite, affects proton relating transport at the proton-pumping site crossing the cell membrane under unlimited carbon and phosphorus conditions. This effect exerts inhibition of phosphorylation under aerobic condition and yields low APT/ADP ratio, consequently decrease poly-P synthesis and phosphorus uptake from outside the cell in the model.

• Toxicological Research
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• 제24권1호
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• pp.23-28
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• 2008

Voltammetric analysis of mercury ions was developed using paste electrodes (PEs) with DNA and carbon nanotube mixed electrodes. The optimized analytical results of the cyclic voltammetry (CV) of the $1{\sim}14ng\;L^{-1}Hg(II)$ concentration and the square wave (SW) stripping voltammetry of the $1{\sim}12ng\;L^{-1}Hg(II)$ working range within an accumulation time of 400 seconds were obtained in 0.1 M $NH_4H_2PO_4$ electrolyte solutions of pH 4.0. For the relative standard deviations of the $1ng\;L^{-1}Hg(II)$, which were observed at 0.078% (n = 15) at the optimum conditions, the low detection limit (S/N) was pegged at $0.2ng\;L^{-1}(7.37{\times}10^{-13}M)$ for Hg(II). The results can be applied to assays in biological fish kidneys and wastewater samples.

• 소성∙가공
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• 제6권3호
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• pp.213-220
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• 1997

The microstructure of the inconel 690 alloy was varied by the solution treatment and the thermal treatment. The specimens having different microstructures were examined in order to understand the strengthening mechanism of the inconel 690. The level of supersaturation of carbon in the solid solution was increased by applying a longer solution treatment at 115$0^{\circ}C$. As increased carbon content in the solid solution, more carbides precipitated during the thermal treatment at $700^{\circ}C$. Since the carbides played a role of obstacle on the movement of dislocations, a higher tensile strength was obtained in the sample having a large number of carbider. The accumulation of dislocations at the grain boundary carbides caused the development of intergranular fracture which led to a lower elongation.

• 한국응용과학기술학회지
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• 제33권4호
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• pp.726-733
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• 2016

A voltammetric analysis of doxycycline was developed using DNA immobilized onto a carbon nanotube paste electrode (PE). An anodic peak current was indicated at 0.2 V (versus Ag/AgCl) in a 0.1M $NH_4H_2PO_4$ electrolyte solution. The linear working range of the cyclic and square wave stripping voltammetry was obtained to $1-27ngL^{-1}$ with an accumulation time of 800 s. Final analytical parameters were optimized to be as follows: amplitude, 0.35 V; frequency, 500 Hz; and pH, 5.43. Here detection limit was found to be $0.45ngL^{-1}$, this result can be applied in foods systems and in the biological diagnostics

• The Korean Journal of Ecology
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• 제21권5_1호
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• pp.427-433
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• 1998

The standing crop and net production were estimated in Moojaechi on Mt. Jungjok. By using the decay model of organic carbon, absolute year of bog peat was calculated. Pollen analysis to bog peat revealed vegetational history and climate change around Moojaechi. The time required for amount of the accumulated peat in the bog was estimated in terms of the balance of the accumulation and decay of organic carbon of the deposit peat. Absolute year of the peat surveyed in this study was about 314 years. Pollen of Pinus was predominant in all the pollen zone, Geamineae and Cyperaceae increased in lower pollen zone while Pinus in upper pollen zone. This showes that climate of the past was probably more humid than that of present. In addition, middle pollen zone showed warming trend which is suggested by high pollen concentration of Quercus, Juglans, Carpinus and Corylus. It suggests that overall environment and vegetation were changed from warmer and more humid to dry condition in Moojaechi and it is considered as the course of boggy ground formation by retrogressive successions.

• KSBB Journal
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• 제15권5호
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• pp.514-520
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• 2000

Simultaneous nitrification and denitrification of ammonia and organic compounds-containing wastewater were performed in a fluidized bed biofilm reactor with polysulfone(PS) hollow fiber as a double layer biomass carrier. The PS hollow fiber fragment has both aerobic and anoxic environments for the nitrifiaction and denitrification at the shell and lumen-side respectively. The reactor system showed about 80% nitrification efficiency stably throughout the ammonia load conditions applied in the experiment. Denitrification efficiency depended on organic load and C/N ratio. High free ammonia concentration and low dissolved oxygen resulted in nitrite accumulation which leads to enhance organic carbon efficiency in denitrification when compared to nitrate denitrification. The simultaneous nitrification and denitrification reactor system has an economic advantages in reduced chemical cost of organic carbon for denitrification as well as compact reactor configuration.

• Toxicological Research
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• 제9권2호
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• pp.167-175
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• 1993

Protective effects of dithiol malonate derivatives (DMDs), YH-100, YH-150 and YH-439 on carbon tetrachloride-induced hepatotoxicity were investigated in primary rat hepatocytes culture. Treatment of DMDs to hepatocytes culture did not affect total cytochrome P-450 content and ECOD and AHH activities. Protein and RNA synthesis was also similar to control. Meanwhile, DMDs significantly decreased LDH release and in vitro lipid peroxidation induced by $CCI_4$. Accumulation of cellular triglyceride and decreased secretion of VLDL from liver cells by $CCI_4$ treatment were also significantly protected.

• 한국응용과학기술학회지
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• 제35권4호
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• pp.1379-1385
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• 2018

The hand held voltammetry systems searched diabetic assay using glucose sensor of fluorine nafion doped carbon nanotube electrode (FCNE). An inexpensive graphite carbon pencil was used as an Ag/AgCl reference and Pt counter electrode. Upon combining and using three electrode systems, optimum square wave (SW) stripping results were attained to 1.0-9.0 ug/L with 8 points. Statistic RSD precision was of 6.02 % with n=15 in 0.1 mg/L glucose. After a total of 200 second accumulation times, analytical detection limit of 0.8 ug/L was obtained. This developed technique was applied to urine samples from diabetic patients urine for fluid analysis, it was determined that the sensor can be used with a diagnostics in the ex vivo of live cells and non treated biological fluid.

• 한국가스학회지
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• 제27권3호
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• pp.134-140
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• 2023

활성탄은 주로 기체나 액체상의 흡착제로 사용되는 탄소질 재료이다. 휘발성 유기화합물의 흡착열 축적 및 산화 등에 의해 화재가 꾸준히 발생함에 따라 석탄과 야자껍질을 원료로 하는 분말 및 입상활성탄을 대상으로 폭발특성 및 열안정성을 평가하였다. 입도분석을 통해 분말활성탄은 입도범위 (0.4~3) ㎛를 가지는 것을 확인하였으며, 시차주사열량계와 열중량분석기를 사용하여 발열개시온도 및 분해거동 등의 열적 특성을 분석하였다. 부유분진에 대한 폭발위험성을 평가한 결과, 석탄계 및 야자계 분말활성탄 모두 St1 등급으로 폭발에 의한 위험성이 약한 분진으로 분류되지만 이는 상대적인 크기를 나타내는 것으로 폭발에 의한 위험성이 절대적으로 작음을 의미하는 것이 아니므로 피해저감을 위한 대책을 수립할 필요가 있다.

• 한국전기전자재료학회논문지
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• 제11권6호
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• pp.465-471
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• 1998

Diamond-like carbon (DLC) films have been prepared by means of the plasma enhanced chemical vapor deposition (PECVD) method using vertical-capacitor electrodes. The deposition rata in our experiment is relatively small compared with that in the conventional PECVD methods, which implies that the accumulation of the neutral $CH_n$ radicals on the substrates due to the gravitational movement may not contribute to the deposition of DLC films. The hardness and the transparency were measured as a function of the ratio of the partial pressure of $CH_4-H_2$ mixtures or the hydrogen contents of specimens. The coefficients of friction between DLC films and a $Si_3N_4$ tip measured by using a lateral force microscope are in the range of 0.024 to 0.033 which depend on the hydrogen contents in DLC, and the surface roughness depends mainly on the deposition rate. The optical gaps increase with increasing the hydrogen contents. DCL films deposited on Pt-coated Si wafers show the stable emission characteristics, and the turn-on fields are in the range of 11 to 20 $V/\mu$m.