• Membrane and Water Treatment
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• 제9권5호
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• pp.327-334
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• 2018

The nano/micro composites with highly porous surface area have attracted of great interest, particularly the synthesis of porous and thin film sheets of high performance. In this paper, an easy method of cost-effective synthesis of thin film ceramic fiber membranes based on Hydroxyapatite, and activated carbon by turned into studied to be applied within the service-facilitated the transport of radioactive waste such as $^{90}Sr$, $^{137}Cs$ and $^{60}Co$) as activated product of radioisotopes from ETRR-2 research reactor and dissolved in 3M $HNO_3$, across a thin flat-sheet supported liquid membrane (TFSSLM). Radionuclides are transported from alkaline pH values. The presence of sodium salts in the aqueous media improves in $HNO_3$, the lowering of permeability because the initial $HNO_3$ concentration is improved. The study some parameters on the thin sheet ceramic supported liquid membrane. EDTA as stripping phase concentration, time of extraction and temperature were studied. The study of maximum permeability of radioisotopes for all parameters. The pertraction of a radioactive waste solution from nitrate medium were examined at the optimized conditions. Under the optimum experimental 98.6-99.9% of $^{90}Sr$, 79.65-80.3% of $^{137}Cs$ and $^{60}Co$ 45.5-55.5% in 90-110 min with were extracted in 10-30 min, respectively. The process of diffusion in liquid membranes is governed by the chemical diffusion process.

• 한국응용과학기술학회지
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• 제23권3호
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• pp.223-229
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• 2006

Methanol and formaldehyde were produced directly by the partial oxidation of methane over mixed oxide catalysts. The catalysts were composed of Mo and Bi with late-transition metals, such as Mn, Fe, and Co. The reaction was carried out at $450^{\circ}C$, 50 bar in a fixed-bed differential reactor. The prepared catalysts were characterized by $O_2-TPD$ and BET apparatus. Among the catalysts used, the catalyst composed of 1:1:2.5 molar ratio of Mo:Bi:Mn showed the best methane conversion and methanol selectivity. The change in ratio of methane to oxygen affected at the conversion and selectivity, and the most proper ratio was 10:1.5. Methane conversion, methanol and formaldehyde selectivities increased with the surface areas of the catalysts. From the $O_2-TPD$ result, it was found that the oxygen species responsible for this reaction might be the lattice oxygen species desorbed at high temperature around $800^{\circ}C$.

• 자원리싸이클링
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• 제16권2호
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• pp.32-39
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• 2007

폐자동차 ASR의 소각재를 대상으로 물리화학적 물성측정 및 리싸이클링을 위한 경량재료 제조실험을 수행하였다. 대상시료는 국내 ASR 소각장에서 채취한 바닥재 2종류와 비산재 4종류이었으며, 이들의 주요 성분 및 입도분석을 실시하고 공정시험법에 의한 중금속 용출량을 조사하였다. 또한, 비산재인 boiler ash를 원료로 하여 경량물질과 무기바인더를 첨가하여 성형 및 소성하는 방법으로 경량재료를 제조하였다. 바닥재에 Cu 함량이 3wt% 내외로 상당히 높은 것으로 나타나 Cu의 사전 분리가 필수적인 것으로 나타났다. 수용성물질을 많이 함유한 SDR(semi-dry reactor) ash와 Bag filter ash의 주성분은 각각 $CaCl_2{\cdot}Ca(OH)_2{\cdot}H_2O$ 및 $CaCl_2{\cdot}4H_2O$인 것으로 나타났다. boiler ash를 원료로 사용하여 제조한 경량재료 시편의 경우 중금속 용출이 크게 감소하였으며, 그 이유는 중금속 성분이 불용성 화합물천 안정화 또는 encapsulation 되었기 때문으로 판단되었다.

• 한국수소및신에너지학회논문집
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• 제17권4호
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• pp.362-370
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• 2006

The purpose of this paper was to investigate the reforming characteristics and optimum operating condition of the plasmatron assisted $CH_4$ reforming reaction for the hydrogen-rich gas production. Also, in order to increase the hydrogen production and the methane conversion rate, parametric screening studies were conducted, in which there were the variations of the $CH_4$ flow ratio, $CO_2$ flow ratio, vapor flow ratio, mixing flow ratio and catalyst addition in reactor. High temperature plasma flame was generated by air and arc discharge. The air flow rate and input electric power were fixed 5.1 l/min and 6.4 kW, respectively. When the $CH_4$ flow ratio was 38.5%, the production of hydrogen was maximized and optimal methane conversion rate was 99.2%. Under these optimal conditions, the following synthesis gas concentrations were determined: $H_2$, 45.4%; CO, 6.9%; $CO_2$, 1.5%; and $C_2H_2$, 1.1%. The $H_2/CO$ ratio was 6.6, hydrogen yield was 78.8% and energy conversion rate was 63.6%.

• 대한기계학회논문집A
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• 제34권1호
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• pp.103-110
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• 2010

본 연구에서는 프랑스의 RCC-MR A16 절차에 기초하여 Mod.9Cr-1Mo 강(ASME Grade 91) 구조의 크리프-피로 균열 개시 및 성장 평가법을 확장 개발하였다. 현재의 A16 지침은 오스테나이트 스테인리스강에 대해서만 크리프-피로 균열 개시 및 성장 평가법을 제시하고 있지만, 현재 초초임계(USC) 화력발전소는 물론 미래형 원자로 시스템의 구조재료로서 폭넓게 채택되고 있는 Mod.9Cr-1Mo 강에 대한 지침은 제시하지 않고 있다. 본 연구에서는 FMS(페리틱-마르텐사이트강)에 대한 크리프-피로 균열 개시 및 성장 평가법을 제시하고 있고, 구조물에 대한 크리프-피로 균열 거동 평가를 수행하였다. 평가결과는 구조시험을 수행한 결과 얻은 관찰 이미지와 비교하였다.

• 생명과학회지
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• 제17권9호통권89호
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• pp.1260-1265
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• 2007

자석으로 분리가 가능한 ${\alpha}-Amylase$가 코팅된 나노고분자를 제조하여 녹말의 분해공정에 활용하였다. 본 연구에서 개발된 고정화 효소의 안정성은 크게 증가하여 상온에서 200rpm으로 교반하면서 보관한 경우 30일 동안에 92.7%의 활성도를 유지하였다 . 고정화 효소를 자석을 이용하여 재사용한 경우 10 회 동안 사용했을 경우 95.2%의 활성도 회수율을 보 여 효소의 재사용 가능성을 확인시켜 주었다 . 고정화 효소 0.5mg을 사용하여 녹말 분해 공정 에 활용하였을 때 2 ml의 40 g/l 녹말 용액을 40분만에 완전히 분해 시켰다, 이러한 고정화 효소를 사용하여 연속 효소반응기를 개발하여 녹말 분해공정에 활용한 결과 체류시간을 1시간으로 하였을 때 녹말 30 g/l를 76% 분해시켜 산업적으로 활용 가능성을 보여 주었다.

• 한국대기환경학회지
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• 제32권5호
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• pp.526-535
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• 2016

Recently, fine dust in atmosphere have been considerably issued as a harmful element for human. Nitrogen oxide ($NO_x$) exhausted from diesel engines and power plants has been disclosed as a main source of secondary production of fine dust. In order to prevent exhausting these nitrogenous compounds into atmosphere, a treatment system with selective catalytic reduction (SCR) catalyst with ammonia as a reductant has been used in various industries. Urea solution has been widely studied to supply ammonia into a SCR catalytic reactor, safely. However, the conversion of urea solution to ammonia has several challenges, especially on a slow conversion velocity. In the present study, a fast urea conversion system including a plasma burner was suggested and designed to evaluate the performances of urea conversion and initial operation time. A designed lab-scale facility has a plasma burner, urea nozzle, mixer, and SCR catalyst which is for hydrolysis of isocyane. Flow rate of methane that is a fuel of the plasma burner was varied to control temperatures in the urea conversion facility. From experimental results, it is found that urea can be converted into ammonia using high temperature condition of above $400^{\circ}C$. In the designed test facility, it is found that ammonia can be produced within 1 min from urea injection and the result shows prospect commercialization of proposed technology in the SCR facilities.

• Environmental Engineering Research
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• 제25권1호
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• pp.114-122
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• 2020

This study was aimed at using the Central Composite Design (CCD) and Box-Behnken Design (BBD) to compare the efficiency and to elucidate the main interacting parameters in the upflow anaerobic sludge blanket (UASB) reactor, namely: Organic Loading Rate (OLR), Hydraulic Retention Times (HRT) and pH at a constant temperature of 35℃. Optimum HRT (15 h), OLR (3.5 kg.m^-3.d^-1) and pH (7) resulted in biogas production of 5,800 mL/d and COD removal of 80.8%. BBD produced a higher desirability efficiency of 94% as compared to the CCD which was 92%. The regression quadratic models developed with high R² values of 0.961 and 0.978 for both CCD and BBD, respectively, demonstrated that the interaction models could be used to pilot the design space. BBD model developed was more reliable with a higher prediction of biogas production (5,955.4 ± 225.3 mL/d) and COD removal (81.5 ± 1.014%), much close to the experimental results at a 95% confidence level. CCD model predictions was greater in terms of COD removal (82.6 ± 1.06% > 80.8%) and biogas production (4,636.31 mL/d ± 439.81 < 5,800 mL/d) which was less than the experimental results. Therefore, RSM can be adapted for optimizing various wastewater treatment processes.

• Nuclear Engineering and Technology
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• 제52권7호
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• pp.1571-1578
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• 2020

As a critical material in very/high-temperature gas-cooled reactors, graphite material directly affects the safety of the reactor core structures. Owing to the complex structures of graphite material in reactors, the material typically undergoes complex stress states. It is, therefore, necessary to study its mechanical properties, failure modes, and strength criteria under complex stress states so as to provide guidance for the core structure design. In this study, compressive failure tests were performed for graphite material under the condition of different confining pressures, and the effects of confining pressure on the triaxial compressive strength and Young's modulus of graphite material were studied. More specifically, graphite material based on the fracture surfaces and fracture angles, the graphite specimens were found to exhibit four types of failure modes, i.e., tension failure, shear-tension failure, tension-shear failure and shear failure, with increasing confining pressure. In addition, the Mohr strength envelope of the graphite material was obtained, and different strength criteria were compared. It showed that the parabolic Mohr-Coulomb criterion is more suitable for the strength evaluation for the graphite material.

• 한국환경과학회지
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• 제11권9호
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• pp.971-977
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• 2002

The isolated strain, Rhodococcus sp. EL-GT was able to degrade high phenol concentrations up to 10 mM within 24 hours in the medium consisting of 5.3 mM $KH_2PO_4$. 95 mM $Na_2HPO_4$, 18mM $NH_4NO_3$, 1 mM $MgSO_4{\cdot}7H_2O$,\;50{\mu}M CaCl_2$,\;0.5 {\mu}M FeCl_3$, initial pH 8.0, temperature $30^{\circ}C$ in rotary shaker at 200 rpm. This strain was good cell growth and phenol degradation in the alkaline pH range range, and the highest in the pH range of 7 to 9. The microorganism was able to grow at the various chlorinated phenols, benzene, toluene, and bunker-C oil. As Rhodococcus sp. EL-GT was good capable of attachment on the acryl media, it would be used as microorganism to consist of biofilm in wastewater treatment.