• Bulletin of the Korean Chemical Society
• /
• 제35권1호
• /
• pp.151-157
• /
• 2014

We have reported the reaction probability, integral reaction cross section, and rate constant for the title system calculated with the aid of a time-dependent wave packet approach. The ab initio potential energy surface (PES) of Prudente et al. (Chem. Phys. Lett. 2009, 474, 18) is employed for the purpose. The calculations are carried out over the collision energy range of 0.05-1.4 eV for the two reaction channels of H + LiH ${\rightarrow}$ Li + $H_2$ and $H_b$ + $LiH_a$ ${\rightarrow}$ $LiH_b$ + $H_a$. The Coriolis coupling (CC) effect are taken into account. The importance of including the Coriolis coupling quantum scattering calculations are revealed by the comparison between the Coriolis coupling and the centrifugal sudden (CS) approximation calculations.

• 방사성폐기물학회지
• /
• 제11권1호
• /
• pp.55-61
• /
• 2013

본 논문에서는 염소화 반응을 통해 Zircaloy-4 (Zry-4) 피복관으로부터 Zr의 회수 연구를 수행하였다. 피복관의 Zr을 전부 $ZrCl_4$로 전환시키기 위해, Zry-4 피복관을 380도에서 70 cc/min $Cl_2$ + 70 cc/min Ar 기체를 이용하여 8시간 동안 반응시켰다. 피복관의 초기 무게는 51.7 g이었으나, 8 시간 반응 후에는 0.49 g만이 잔류물로 남아있는 것을 확인하였는데 이는 초기 무게의 0.95wt%에 해당하는 값이다. 반응 생성물의 무게는 121.7 g 이었으며, Zr의 순도는 99.80wt%였다. 주요 불순물로는 Fe (0.18wt%)와 Sn (0.02wt%)를 확인할 수 있었다. 실험 결과를 통해 확인한 Zr의 회수율은 96.95wt%였으며, 실험상 손실은 2.34wt%로 확인되었다. 반응 잔류물의 관찰을 통해 염소화 반응이 길이 방향으로 주로 일어나며, 표면의 산화층이 반응 잔류물로 남는다는 것을 확인할 수 있었다. 본 연구를 통해 확인된 Zr의 높은 순도와 회수율은 염소화 공정이 폐 피복관 처리 방법으로 매우 유망한 기술임을 의미한다고 볼 수 있다.

• 한국식품과학회지
• /
• 제34권2호
• /
• pp.194-199
• /
• 2002

8품종의 국산밀에 대한 이화학적 특성 및 white layer cake 제조 특성을 조사하였다. 국산밀의 제분율은 $62.5{\sim}71.8%$의 분포로 품종간의 차이가 큰 것으로 나타났다. 국산밀가루의 단백질 함량은 $7.70{\sim}10.58%$의 범위였으며, 회분 함량는 $0.51{\sim}0.71%$의 범위로 수입밀 박력분에 비해 다소 높았다. 국산밀가루의 mixograph 반죽특성에서 우리밀, 알찬밀, 올그루밀의 반죽 물성이 매우 약해 cake의 제조에 적합하였고 은파밀, 그루밀은 단백질 함량에 비해 안전성이 다소 떨어졌으며, 금강밀과 탑동밀가루는 반죽의 안정성이 높은 경질밀의 특성을 보여 cake의 제조에 부적합함을 보여주었다. 국산밀 cake반죽의 pH와 비중은 각각 $6.71{\sim}7.08,\;0.73{\sim}0.76\;g/cc$의 범위로 박력분 반죽과의 차이가 크지 않은 것으로 나타났다. White layer cake의 부피, 비체적은 각각 $837.5{\sim}952.5\;cc,\;2.16{\sim}2.40\;cc/g$의 범위로 알찬밀이 가장 높은 값을 주었다. 국산밀 cake은 symmetry와 uniformity에서 박력분 제조 cake 보다 약간 떨어지는 경향을 주었다. 국산밀 cake의 crumb 색도는 박력분 보다 다소 어둡고 황색도가 높은 것으로 나타났다. 국산밀 cake의 텍스쳐는 품종에 따라 차이를 보였으며 알찬밀, 우리밀에서 경도가 낮아 부드러운 것으로 나타났다.

• Journal of Biosystems Engineering
• /
• 제23권5호
• /
• pp.445-456
• /
• 1998

This study was carried out to evaluate the performance of a medium scale rice polisher of 2.5 t/h and to improve its performance for producing the clean rice with high quality. The maximum internal pressure, broken rice ratio. whiteness in the rice polisher were investigated, and the effects of outlet resistance, water spraying rate, shaft revolution speed and rice moisture content on the polishing performance were analyzed to find out proper operating conditions. The conclusions of this study were as follows: 1. In the performance evaluation of the polisher, the broken rice ratio increment of 0.1%, the max. internal pressure of about 11 N/${cm}^2$, and whiteness increment of 2.2~3.7 resulted at the conditions of 20 PS driving power, 950 rpm, 150 cc/min water spraying rate, 44.1 Nㆍcm outlet resistance and about 15% rice moisture content. 2. Though max. internal pressure and whiteness at the 17% rice moisture content were higher than those at the 15% moisture content under the same operating conditions of the polisher, but the broken rice rate at the 17% moisture content was absolutely low compared with that at 15% moisture content. The water spraying effect to reduce broken rice and to increase whiteness was much significant at the 15% moisture content not significant at 17% moisture content. 3. The main parameter of the performance was outlet resistance, and low resistance of about 44.1 Nㆍcm was recommended at the polisher. 4. The proper water spraying rate in the polisher was about 150 cc/min. 5. As the shaft revolution speed decreased from 950 rpm and 800 rpm to 650 rpm, the broken rice ratio increased and whiteness decreased. 6. As the driving power of the polisher increased from 20 PS to 30 PS, the max. internal pressure decreased by about 1~2.5 N/${cm}^2$ and whiteness increased by about 1~2, but the broken rice rate was not changed. 7. The proper operating conditions of the polisher seemed to be the revolution speed of 800-950 rpm, the water spraying rate of about 150 cc/min, the oulet resistance of about 44.1 N.cm and 30 PS driving power.

• 자원환경지질
• /
• 제12권1호
• /
• pp.13-15
• /
• 1979

Iron ore waste discarded around Choong-ju iron district, Choongchong-Bukdo is as low as 25 per cent of iron, mainly consisting of hematite and magnetite. In this mineral dressing test procedure 93 per cent of magnetite was separated and concentrated into the magnetite concentrate as high as 62 per cent. The remaining sample, mostly, hematite averages about 19.8 per cent of iron which can be concentrated with very good results with the optimum flotation conditioning-pH 3.0 and 3 cc per litre of aero-promoter #845 (0.5% sol.) and 1.5cc per litre of hydro-fluoric acid (40% sol.) and four times of cleaning flotation. Hematite concentrate averages 64.2 per cent of iron. The overall iron concentrate averages 63 per cent of iron with recovery 86 per cent of iron contained.

• KSBB Journal
• /
• 제14권6호
• /
• pp.696-701
• /
• 1999

본 연구에서는 lipase를 이용해서 ricinoleic acid를 대량생산하기 위해 피마자유의 완전가수분해 조건을 찾고자 하였다. 널리 알려진 lipase CR, lipase CC, lipase PP를 대상으로 피마자유의 가수분해의 가능성을 시험하고, 유기용매를 사용함으로써 가수분해도를 향상시킬 수 있음을 확인하였다. 일반적으로 lipase의 활성을 감소시키는 극성용매의 경우 피마자유의 가수분해에 있어서도 효소의 활성을 감소시켰고, 물과 섞이지 않는 hydrophobic solvent가 피마자유의 가수분해도를 크게 증가시키는 것을 확인하였다. 본 연구에서는 isopropyl ether의 효과가 가장 크며, 조건에 따라 가수분해도를 두 배 이상 증가시킨다는 것을 확인하였다. 그리고 유기용매를 사용함으로써 pH의 영향을 바꾸거나 감소시킬 수 있다는 사실도 확인하였다. 용매와 물의 부피비에 의해서 가수분해가 영향을 받는다는 사실과 특히 유기용매보다는 물의 양에 절대적으로 영향받는다는 사실을 발견하였다. 하지만, 물과 유기용매의 부피비와 함께 lipase와 피마자유의 무게비도 매우 중요하다는 것을 확인하였다. 30$^{\circ}C$에서 isopropyl ether를 사용할 경우 무게 비로 2 wt%일 때는 약 82%, 4 wt% 이상의 lipase CC나 lipase CR을 사용하면 피마자유가 완전히 가수분해되는 사실을 발견하였다.

• 한국응용과학기술학회지
• /
• 제19권3호
• /
• pp.213-221
• /
• 2002

Activated carbons with high surface area of 2,600 $m^{2}/g$ and high pore volume of 1.2 cc/g could be prepared by KOH activation of rice hulls at a KOH:char ratio of 4:1 and $850^{\circ}C$. In order to increase the adsorption capacity of hydrogen sulfide, which is one of the major malodorous component in the waste water treatment process, various contents of $Na_{2}CO_{3}$ and $KIO_{3}$ were impregnated to the rice-hull activated carbon. The impregnated activated carbon with 5 wt.% of $Na_{2}CO_{3}$ showed improved $H_{2}S$ adsorption capacity of 75 mg/g which is twice of that for the activated carbon without impregnation and the impregnated activated carbon with 2.4 wt.% of $KIO_{3}$ showed even higher $H_{2}S$ adsorption capacity of 97 mg/g. The improvement of $H_{2}S$ adsorption capacity by the introduction of those chemicals could be due to the $H_{2}S$ oxidation and chemical reaction with impregnated materials in addition to the physical adsorption of activated carbon.

• 한국자기학회지
• /
• 제5권5호
• /
• pp.819-823
• /
• 1995

The oil-based magnetic fluids were sysnthesized using ultra-fine $Fe_{3}O_{4}$ powder dispersed in hydrocarbon oil. To synthesize ultra-fine $Fe_{3}O_{4}$, we carried out the experiments varying the pH of reacting medium and the initial concentration of $Fe^{2+}$. We also investigated the amount of oleic acid to obtain a stable dispersion and the proper base oil of MF for loudspeaker application. The limits of adsorbed amount of oleic acid on the $Fe_{3}O_{4}$ surface were approximately 35~40 percents of the total magnetite weight. As the $Fe_{3}O_{4}$ content increased from 0.1g/cc to 0.6g/cc, the viscosity of oil-based magnetic fluid increased from 1,063cP to 1,828cP, and its saturation magnetization at 10kOe increased from 66G to 242G. When we tested the MF sample to a commercial speaker, improvements were noted.

• Bulletin of the Korean Chemical Society
• /
• 제24권6호
• /
• pp.792-796
• /
• 2003

Polychlorinated dibenzo-p-dioxins (PCDDs) are extremely toxic and persistent environmental pollutants. Their chemical reactivities and other physicochemical/biological properties show a strong dependence on the chlorination pattern. With increasing the number of chlorines, dioxin congeners become more electronegative and gain higher electron affinities. The vertical electron affinities (VEA) are related with the LUMO energies of neutral molecules. LUMO energies of all PCDD congeners were calculated at the B3LYP/6-31G** level and those of some selected congeners at the level of B3LYP/6-311G**//B3LYP/6-31G** and B3LYP/cc-pvtz/ /B3LYP/6-31G**. The total energies of neutral and anionic species for dibenzo-p-dioxins (DD), 1469-TCDD, 2378-TCDD, and OCDD were calculated at the level of B3LYP/6-31G**, B3LYP/aug-cc-pvdz, and B3LYP/ aug-cc-pvtz//B3LYP/6-31G**. By using the four congeners with D2h symmetry as reference molecules, we could estimate VEA (B3LYP/aug-cc-pvdz) of 75 PCDD congeners based on the linear correlations between LUMO energy and VEA (B3LYP/6-31G**) and between VEA (B3LYP/6-31G**) and VEA (B3LYP/aug-ccpvtz// B3LYP/6-31G**). Results show that all PCDDs with the number of Cl ≥ 3 have positive electron affinities. The PCDD electron affinity values provided in this work can be a useful data set in understanding the congener-specific reactivities of dioxins in various environmental media.

• Archives of Pharmacal Research
• /
• 제20권2호
• /
• pp.158-170
• /
• 1997

New HMG-CoA reductase inhibitors, in which 3-substituted 4, 5-polymethylenepyrazoles are employed as a hydrophobic anchor connected to tetrahydro-4-hydroxy-2H-pyran-2-one by a two-carbon bridge, were designed and synthesized to exhibit significant inhibitory activity comparable to mevinolin. The most potent enzyme inhibitor $(11cc, IC_{50}=0.01{\mu}M)$ is 4-fold more potent than lovastatin.