• 한국수소및신에너지학회논문집
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• 제30권3호
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• pp.201-208
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• 2019

Recently, a fuel reforming plant for supplying high purity hydrogen is being applied to submarines. Since steam reforming is an endothermic reaction, it is necessary to continuously supply heat to the reactor. A fuel reforming plant for a submarine needs a multi-stage burner (MSB) to acquire heat and convert the combustion gas to $CO_2+H_2O$. The MSB has problems that the combustion imbalance occurs during start-up due to the temperature restriction of the combustion gas. This problems can be solved by burning $H_2O$ together with fuel and $O_2$. In this study, the simulation results of MSB were analyzed to determine the optimum flow rate of $H_2O$ supplied to the 6-stage burner. When the flow rate of $H_2O$ was low, combustion was concentrated on the burner#6 in comparison with the burner#1-#5. This combustion concentration improved as the supply amount of $H_2O$ increased. As a results, it was necessary to supply at least 4.9 kmol/h of $H_2O$ (per 1 kmol/h of fuel) to burner#1 in order to maintain the combustion gas temperature of each stage at $750^{\circ}C$ and to convert the final stage burner gas composition to $CO_2+H_2O$.

• 공업화학
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• 제30권2호
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• pp.190-197
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• 2019

활성탄을 사용하여 수용액으로부터 메틸 그린 염료의 흡착에 대해 초기농도와 접촉시간 및 온도를 흡착변수로 사용하여 조사하였다. 흡착평형관계는 Freundlich 등온식에 잘 맞았다. 평가된 Freundlich 분리계수(1/n = 0.212~0.305)로부터 이 흡착공정이 효과적인 처리영역(0 < $R_L$ < 1)에 속하는 것을 알았다. BET식으로부터 얻은 등온포화용량은 온도가 증가할수록 커졌다. Dubinin-Radushkevich식으로 구한 흡착에너지값(E = 316.869~340.049 J/mol)으로부터 흡착공정이 물리흡착공정임을 알았다. 흡착속도실험결과는 유사 2차 반응속도식에 잘 맞는 것으로 나타났다. 자유에너지(-5.421~-7.889 kJ/mol)와 엔탈피(31.915 kJ/mol)는 흡착공정이 자발적이고 흡열반응으로 진행되었다고 알려주었다. 등량흡착열은 평형흡착량이 증가함에 따라 커졌으며, 표면 덮임이 증가됨에 따라 흡착제-흡착질의 총 상호작용도 증가하였다.

• Nuclear Engineering and Technology
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• 제53권1호
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• pp.164-171
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• 2021

The europium sorption on Tamusu clay was investigated by batch sorption experiments and spectroscopic study under the condition of strong ionic strength. The results demonstrated that europium sorption on Tamusu clay increased rapidly with pH value, but decreased with the ionic strength of solution increased. The europium sorption also increased in the presence of humic acid, especially at low pH value. The sorption could be fitted by Freundlich isotherm model and the europium sorption on clay was spontaneous and endothermic reaction. Besides, the result indicates that ion exchange was the main process at low pH value, while inner-sphere surface complexation dominated the sorption process at high pH value. The Backscatter electron scanning/Energy Dispersive Spectrometer(BSE/EDS) and the effect of Na for europium sorption results further suggested that europium sorption on Tamusu clay mainly competed with Na at low pH value. Overall, the results in this research were of significance to understand the sorption behavior of europium on the geological media under high ionic strength.

• 한국환경농학회지
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• 제40권4호
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• pp.239-247
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• 2021

BACKGROUND: Enormous amounts of the wood biomass wastes have been produced through various wood processing. This study characterizes the surface characteristics of biomass powders of Cornus controversa (CC) and Quercus mongolica (QM) and investigates their removal efficiency and mechanism for Pb (II) in aqueous solution on which to base potential recycling alternative of the wood biomass. METHODS AND RESULTS: Batch experiments were conducted under different conditions of Pb concentrations, temperatures, time and solid/solution ratios. Adsorption isotherm of Pb by CC and QM biomass was explained significantly by the Langmuir model, indicating Pb was likely adsorbed on the monolayer of the surfaces. The adsorption kinetics were fitted significantly to the double first-order model consisting of rapid and slow steps. The respective rate constants (k1) of CC and QM for the rapid adsorption kinetic steps were 0.051 and 0.177 min^-1, and most of the sorption reactions proceeded rapidly within 6-20 minutes. The maximum adsorption quantities (q_max) of Pb were 17.25 and 23.47 mg/g for CC and QM, respectively. Thermodynamic parameters revealed that adsorption of Pb on the biomass of CC and QM was a spontaneous endothermic reaction. CONCLUSION(S): Results demonstrate that biomass wastes of CC and QM can be used as Pb adsorbents judging from adsorption isotherm, kinetics, and thermodynamic parameters.

• 한국환경과학회지
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• 제31권8호
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• pp.691-706
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• 2022

Magnetic activated carbon was prepared by adding a magnetic material to activated carbon that had been prepared from waste citrus peel in Jeju. The adsorption characteristics of an aqueous solution of the antibiotic trimethoprim (TMP) were investigated using the magnetic activated carbon, as an adsorbent, and response surface methodology (RSM). Batch experiments were carried out according to a four-factor Box-Behnken experimental design affecting TMP adsorption with their input parameters (TMP concentration: 50~150 mg/L; pH: 4~10; temperature: 293~323 K; adsorbent dose: 0.05~0.15 g). The significance of the independent variables and their interaction was assessed by ANOVA and t-test statistical techniques. Statistical results showed that TMP concentration was the most effective parameter, compared with others. The adsorption process can be well described by the pseudo-second-order kinetic model. The experimental isotherm data followed the Langmuir isotherm model. The maximum adsorption capacities of TMP, estimated with the Langmuir isotherm model were 115.9-130.5 mg/g at 293-323 K. Also, both the thermodynamic parameters, ΔH and ΔG, have both positive values, indicating that the adsorption of TMP by the magnetic activated carbon is an endothermic reaction and proceeds via an involuntary process.

• 한국분말재료학회지
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• 제31권2호
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• pp.132-136
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• 2024

This study investigated the effects of revolution speed and ball size in planetary milling on the microstructure and dehydrogenation behavior of TiH₂ powder. The particle size analysis showed that the large particles present in the raw powder were effectively refined as the revolution speed increased, and when milled at 500 rpm, the median particle size was 1.47 ㎛. Milling with a mixture of balls of two or three sizes was more effective in refining the raw powder than milling with balls of a single size. A mixture of 3 mm and 5 mm diameter balls was the optimal condition for particle refinement, and the measured median particle size was 0.71 ㎛. The dependence of particle size on revolution speed and ball size was explained by changes in input energy and the number of contact points of the balls. In the milled powder, the endothermic peak measured using differential thermal analysis was observed at a relatively low temperature. This finding was interpreted as the activation of a dehydrogenation reaction, mainly due to the increase in the specific surface area and the concentration of lattice defects.

• 한국도로학회논문집
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• 제7권4호
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• pp.113-123
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• 2005

본 연구에서는 기존의 염화물계 제설제인 염화칼슘$(CaCl_2)$ 및 염화나트륨(NaCl)과 비염화물계 제설제(NS 100) 초산화합물 함유 염화물 제설제(NS 40), 그리고 이들 제설제를 중량대비 일정비율로 혼합$(NaCl\;70%+CaCl_2\;30%,\;NS\;40\;70%+CaCl_2\;30%,\;NaCl\;70%+NS\;40\;30%,\;NS\;40\;70%+NaCl\;30%)$하였을 때 제설성 능과 특성, 콘크리트의 동결융해저항성 및 강재의 부식에 미치는 영향을 실내시험을 통하여 비교 검토하였다. 이상의 시험결과를 바탕으로 동절기 구조물이 동해를 받을 수 있는 지역에서 염화물계 제설제를 사용할 경우 제설성능 및 효과, 강재의 부식성 콘크리트의 동결융해저항성 및 스켈링저항성에 미치는 영향을 고려해 볼 때 하나의 제석제를 사용하기 보다는 두가지 제설제를 적정 비율로 혼합하여 사용하는 것이 바람직한 방법임을 알 수 있었다. 혼합 사용시에는 제설성능 강재 및 콘크리트에 미치는 영향을 고려해 볼 때 NS40(70%)+염화칼슘(30%)이 가장 효과적인 것으로 나타났다.

• 한국광물학회지
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• 제18권2호
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• pp.109-115
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• 2005

딕카이트로부터 스멕타이트를 수열법으로 합성하고 XRD, IR, TG, DTA, EDS 및 XRF를 사용하여 물리${\cdot}$화학적 특성을 분석하였다. 합성 스멕타이트에 대해 Greene-Kelly 시험을 한 결과, 베이델라이트임을 확인하였다. IR 분석결과, 합성 베이델라이트의 Al-OH 진동에 의한 특징적인 흡수띠인 818, $770\;cm^{-1}$ 피크가 관찰되었으므로 순수한 베이델라이트임을 확인되었다. DTA-7G 실험결과 합성된 베이델라이트는 약 $16\%$의 수분을 함유하고 있었으며, $117^{\circ}C$에서 탈수 작용이 발생하고, $482^{\circ}C$와 $685^{\circ}C$ 두 곳에서 탈수산화 작용에 의한 흡열 반응이 나타났다. 또한, $1028^{\circ}C$에서 합성 반응물은 뮬라이트와 크리스토발라이트로 재결정되었다. CEC, M.B. 시험 및 팽윤도를 분석한 결과, 각각 $l16\~l18$ cmol/kg, $84\~91\%,\;29\~32$ mL/2 g으로 양호한 결과를 나타내었다. EDS 및 XRF 분석 결과, 구조식은 $Na_{0.5}Al_{2.5}Si_{3.5}O_{10}(OH)_2$이었다.

• 한국수소및신에너지학회논문집
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• 제11권1호
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• pp.43-49
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• 2000

현재 증기나 온수에 의한 열수송은 배관을 통하여 열손실 및 마찰손실 등이 발생하므로 수송거리는 3 내지 5km가 한계이다. 그러나 대부분의 공단이 도시지역에서 10km 이상 떨어져 있으므로 이들 지역에서 발생되는 폐열을 적절히 활용하기 위해서는 새로운 열수송 시스템이 개발되어야 한다. 수소저장합금은 수소를 흡수 또는 방출하면서 발열반응과 흡열반응을 일으키는 특성을 가지고 있으므로 산업공단지역의 폐열로부터 수소저장합금의 수소를 방출시키고, 이 수소를 인근 도시지역에 파이프라인으로 수송한 후 필요시 또 다른 수소저장합금과 반응시켜 열을 얻을 수 있다. 이 시스템에서는 난방의 목적 외에도 수소의 흡수 방출온도가 낮은 합금을 이용하여 냉열을 얻을 수도 있다. 따라서 수소저장합금은 폐열의 저장이나 열수송의 수단으로 활용할 수 있다. $MmNi_{4.5}Al_{0.5}Zr_{0.003}$, $LaNi_5$, $Zr_{0.9}Ti_{0.1}Cr_{0.6}Fe_{1.4}$, $MmNi_{4.7}Al_{0.1}Fe_{0.1}V_{0.1}$ 합금들이 열수송에 적합한 합금으로 선정되어 그 특성을 검토하였으며, 열수송시스템의 설계 및 제어기술에 대하여 검토하였다.

• 한국식품영양학회지
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• 제29권3호
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• pp.371-381
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• 2016

The present study investigated the effects of processing parameters such as time (10, 20, 30, 40 min), pressure (25, 50, 75, 100 MPa), and the salinity of brine (0~10%(w/v)) on jacopever (Sebastes schlegeli Hilgendorf) in order to establish optimization of the three factors using a high hydrostatic pressure (HHP) machine. To do so, it analyzed the quality characteristics of volatile basic nitrogen (VBN), trimethylamine (TMA), total bacterial counts, dynamic viscoelasticities, and differential scanning calorimetry (DSC) properties. First, when the time increased to 40 mins, by 10 min intervals, the total bacterial counts in HHP groups under $25^{\circ}C$, 100 MPa, and 4%(w/v) brine were significantly decreased except for the first 10 min in comparison to the control group. In regards to DSC properties, the onset temperature ($T_O$) of the first endothermal curve was significantly reduced. Second, when the pressure level increased up to 100 MPa by 25 MPa increments, the total bacterial counts in the HHP samples significantly decreased for 20 min at 50 MPa or higher. As the pressure increased, G', G" and the slope of tan ${\delta}$ decreased (except for 50 MPa). Third, in regards to the salinities of brine, when the HHP processing was treated at 100 MPa, $25^{\circ}C$ for 20 min, the total bacterial counts of all the HHP groups significantly decreased in comparison to those of the control group. A significant difference was found in the enthalpy of the second endothermic curve in the 6~10%(w/v) (except 7%(w/v)) HHP groups. Therefore, the salinity of the immersion water under the HHP condition was appropriate when it was lower than 6%(w/v). The present study demonstrated that the optimum parameter condition according to/under the condition of the microbial inhibition and economic effects using an HHP would be the reaction time for 20 min, reaction pressure at 100 MPa, and the salinity of 4%(w/v) brine.