• Bulletin of the Korean Chemical Society
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• 제20권11호
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• pp.1335-1339
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• 1999

The function of 5S rRNA, a constituent of a large subunit of ribosome, is not clearly known yet. To identify RNA motifs interacting with 5S rRNA, and thereby to get an insight into the function of 5S rRNA in the ribosome, a SELEX (Systematic Evolution of Ligands by Exponential Enrichment) experiment was performed. RNA molecules binding to Escherichia coli 5S rRNA were selected from a 48-mer random sequence library through 12 rounds of selection, cloned, and sequenced. Two groups of the selected RNA molecules had the consensus sequences GCGG and GUGAAA, respectively, which are present in the segment, G688 through A696, of E. coli 16S rRNA. The gel mobility shift assay showed that 5S rRNA interacted with the 16S rRNA fragment containing the GCGG and GUGAAA sequences. The enzymatic protection experiment shows that the A29CCUGA34 and G51AAGUG56 sequences of 5S rRNA and the C680AGG683 and G688CGG691 sequences of the 16S rRNA fragment are involved in the interaction between the two RNA molecules. On the basis of this observation, we suggest that 5S rRNA and 16S rRNA play a role for the association of two ribosomal subunits.

• 웰빙융합연구
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• 제6권3호
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• pp.33-36
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• 2023

Purpose: Since the food wastewater contains a high concentration of nitrogen, it is very important to find a way to efficiently remove it. Research design, data and methodology: A total of four experiments were conducted under different conditions to remove ammonia nitrogen present in the food wastewater. The experiment was designed by adding sodium hypochlorite to the raw food wastewater and varying conditions such as pH control, aeration/precipitation, and stirring. Results: The ammonia nitrogen removal rate in Experiment 1 was about 12% (sodium hypochlorite added), ammonia nitrogen increased about 4.7% in Experiment 2 (sodium hypochlorite added after aeration/precipitation in a bioreaction tank, stirring), and decreased about 52.5% (sodium hypochlorite added after controlling and stirring). Conclusions: When the concentration of sodium hypochlorite was high, ammonia nitrogen was best removed, and the pH was adjusted to 12, and sodium hypochlorite was added after stirring, and the removal was the second best. If the method of this study is further studied and developed, it can be basic data for ammonia nitrogen removal in the future.

• 한국연초학회지
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• 제4권2호
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• pp.75-80
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• 1982

During the process of curing of the tobacco (Nicotiana tabacum L. ) leaves the concentration change of Nonvolatile organic acids and Higher fatty acids of the flue-cured tobacco leaves was observed. The contents of Nonvolatile organic acids in flue-cured tobacco leaves were as follows, malic> oxalic>malonic>citric>succinic acid. Higher fatty acids was linolenic>Palmitic>oleic >stearic$\geqq$linoleic acid, Citric acid content of last curing time was increased about 4~5 times in compare to before curing tobacco. It was concluded that significant changes of three variety flue-cured tobacco but a significant difference was observed in the composition of Daegu gold variety.

• 대한화학회지
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• 제10권2호
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• pp.76-90
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• 1966

Ammonium sulfate synthesized by the air oxidation methods without catalyst using the reaction vessel which was fitted with fritted glass at the bottom of it and introducing, through the bottom, ammonia and air with constant flow rates to sulfurous acid solution of constant concentrations at the given temperatures. The experiment showed that the oxidation process was accelerated in accord with the increase of the air flow rates when the ammonia flow rate was constantly kept at ca. 100ml/min. in high temperatures. When the pH of the solution reached 9.0, the oxidation was nearly completed. It is assumed that in the process of reaction, $[O_{2}{\to}HSO_{3}^-]^{\neq}$ would be produced as an activated complex and the reaction was thought to be first order. The experiment indicated that the 0.5M sulfurous solution could be oxidized up to 98.54% at the flow rates of ammonia and air, 100ml/min., and 4l/min., respectively at $50^{\circ}C$.

• Environmental Engineering Research
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• 제18권3호
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• pp.157-161
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• 2013

Treatment of textile wastewater by the electrocoagulation (EC) process is being investigated by this experimental study. The objective of this experiment is to observe the efficiency of the EC process in removing chemical oxygen demand (COD) and turbidity. In this experiment an iron electrode is used in the EC process, and different working parameters such as pH, current density and operating time were studied in an attempt to achieve a higher removal capacity. The results show that the maximum COD removal occurred at neutral pH at operating time 30 min. COD and turbidity removal reaches at maximum, with optimum consumption of electrodes, between current density 85-95 $A/m^2$, and only trace amounts of metals were determined in the EC treated effluent.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2004년도 추계학술대회 논문집 Vol.17
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• pp.711-714
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• 2004

Chemical mechanical polishing (CMP) has been widely accepted for the global planarization of multi-layer structures in semiconductor manufacturing. However, it still has various problems to the CMP equipment, in particular, among the CMP components, process variables are very important parameters in determining the removal rate and non-uniformity. Using a design of experiment (DOE) approach, this study was performed investigating the interaction between the various parameters such as turntable and head speed, down force and back pressure during CMP. Using statistical analysis techniques, a better understanding of the interaction behavior between the various parameters and the effect on removal rate, no-uniformity and ETC (edge to center) is achieved.

• Bulletin of the Korean Chemical Society
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• 제20권4호
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• pp.445-450
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• 1999

Molecular dynamics (MD) simulation of non-rigid H-Y zeolite framework are performed at 298.15 and 5.0 K. Usual bond stretching, bond angle bending, torsional rotational, and non-bonded Lennard-Jones and electrostatic interactions are considered as intraframework interaction potentials. Calculated atomic parameters are in good agreement with the experiment, which indicates the successful reproduction of the framework structure and its motion. Both calculated bond lengths and bond angles are also in good agreement with the experiment except generally for a little longer bond lengths and a little smaller T-O-H bond angles. The calculated overall site occupation of HI keeps the order O(2) > O(3) > O(4) > O(t) at 298.15 K, which is very different from the experimental prediction, O(l) > O(3) > O(2) at 5 K. Calculated IR spectra of the H-Y zeolite framework show that most of the main peaks of the O-H bonds are in the broad region 3700-5000 cm-1 and that the O-T stretching bands appeared in 0-2000 cm-1 and at 2700 cm-1

• Bulletin of the Korean Chemical Society
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• 제9권4호
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• pp.202-206
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• 1988

In order to investigate the oligomerization state of the plasma membrane proteolipid apoprotein purified from the bovine kidney, fluorescence polarization experiment was carried out in the two different solvent systems, i.e., water and organic solvent(chloroform-methanol). The molecular volumes of the proteins estimated from the Perrin equation, were to be 45,258$A^3$ and 17,608$A^3$ in water and organic solvent, respectively. These values indicate that a trimerization is possibly occurring in the aqueous environment. As an auxiliary experiment for the calculation of the molecular volume using Perrin equation, fluorescence quenching constants ($K_q$) with the quencher acrylamide and fluorescence lifetimes (${\tau}_F$) of the intrinsic fluorophore tryptophan residue were estimated in the two different solvent systems. $K_q$ in water was 18.21$M^{-1}$ and it was 46.24$M^{-1}$ in organic solvent. Fluorescence lifetimes of tryptophan residue were calculated to be 2.80 nsec. in water and 3.81 nsec. in organic solvent, respectively.

• 대한화학회지
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• 제47권5호
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• pp.487-494
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• 2003

이 연구에서는 탐구화학실험을 통해 고등학교 학생들의 과학 성취도 향상정도를 논리적 사고력, 과학탐구기능, 실험 태도, 수공적 기능, 탐구과정 기능 등의 측면에서 조사하였다. 이를 위해 수도권 소재의 남녀 고등학교 2개교의 5개조 150명을 대상으로 하여 논리적 사고력, 과학탐구기능의 지필평가와 탐구과정 기능의 보고서평가, 실험태도, 수공적 기능의 실험관찰 평가를 통하여 자료를 수집하였다. 연구 결과에 의하면 학생들의 탐구과정기능과 실험 태도, 수공적 기능은 전반적으로 매우 낮은 수준으로 조사되었으나 탐구과정 기능을 제외 한 나머지의 측면에서는 유의미한 향상을 보였다. 또한 탐구화학실험이 지속적으로 수행될 때 학습자의 과학 성취도가 향상됨을 알 수 있었다.

• 공업화학
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• 제34권3호
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• pp.327-329
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• 2023

본 연구에서는 Clostridium ljungdahlii 배양에서 유기질소공급물인 tryptone과 sodium tungstate의 배양액 내 농도가 균주 성장과 아세트산, 에탄올 생산에 대한 영향을 확인하기 위한 실험을 수행하였다. 대조군 실험의 배지 조건(0 g/L tryptone)보다 tryptone 2.5 g/L를 투입한 경우 균주 성장이 144.6% 증가하였고, 에탄올 및 아세트산 생산은 각각 8.6%와 36.7% 향상되었다. 대조군 실험에 사용된 배지의 조건(0.01 µM Na₂WO₄·2H₂O)보다 100배인 1 µM Na₂WO₄·2H₂O를 사용한 실험군에서, 균주 성장과 C2 대사산물의 총생산량에는 큰 차이가 없지만, 에탄올 생산 증가하고 아세트산 생산은 감소하여 에탄올/아세트산 생산비가 0.56로 대조군의 0.24에서 크게 증가하였다.