• 대한조선학회논문집
• /
• 제61권1호
• /
• pp.51-60
• /
• 2024

Hi Air Korea and Hanwha ocean are currently developing an Onboard Carbon dioxide Capture System (OCCS) to absorb CO₂ emitted from ship's engine using a sodium hydroxide(NaOH) solution, and converting the resulting salt into a solid form through a chemical reaction with calcium oxide (CaO). The system process involves the following steps; 1)The reaction of CO₂ gas absorption in water, 2)The reaction between carbonic acid (H₂CO₃) and NaOH solution to produce carbonate or bicarbonate, and 3)The reaction between carbonate or bicarbonate and CaO to form calcium carbonate (CaCO₃). And ultimately, the solid material, CaCO₃, is separated and discharged using a separator. The OCCS has been installed on an ship and the test results have confirmed significant reduction effects of CO₂ in the ship's exhaust gas. A portion of the exhaust gas emitted from the engine was transferred to the OCCS using a blower. The flow rate of the transferred gas ranged from 800 to 1384 m³/hr, and the CO₂ concentration in the exhaust gas was 5.1 vol% for VLSFO, 3.7 vol% for LNG and a 12 wt% NaOH solution was used. The results showed a CO₂ capture efficiency of approximately 42.5 to 64.1 vol% and the CO₂ capture rate approximately 48.4 to 52.2kg/hr. Additionally, to assess the impact of the discharged CaCO₃on the marine ecosystem, we conducted "marine ecotoxicity test" and performed Computational Fluid Dynamics (CFD) analysis to evaluate the dispersion and dilution of the discharged effluent.

• Advances in environmental research
• /
• 제2권1호
• /
• pp.35-49
• /
• 2013

Research work on removal of fluoride from water, referred to as water defluoridation, has resulted into the development of a number of technologies over the years but they suffer from either cost or efficiency drawbacks. In this work, enhancement effects of phosphate and silicate on defluoridation of water by low-cost Plaster of Paris (calcined gypsum) were studied. To our knowledge, the influence of silicate on defluoridation was not reported. It was claimed, that the presence of some ions in the treated water samples, was decreasing the fluoride removal since these ions compete the fluoride ions on occupying the available adsorption sites, however, phosphate and silicate ions, from its sodium slats, have enhanced the fluoride % removal, hence, precipitation of calcium-fluoro compounds of these ions can be suggested. Percentage removal of $F^-$ by neat Plaster is 48%, the electrical conductance (EC) curve shows the typical curve of Plaster setting which begins at 20 min and finished at 30 min. The addition of phosphate and silicate ions enhances the removal of fluoride to high extent > 90%. Thermodynamics parameters showed spontaneous fluoride removal by neat Plaster and Plaster-silicate system. The percentage removal with time showed second-order reaction kinetics.

• 상하수도학회지
• /
• 제8권1호
• /
• pp.18-26
• /
• 1994

This research investigated efficient operation mode for the successful performance of SBR(sequencing batch reactor) treating fish processing wastewater, and the effect of sodium chloride (NaCl) on treatment efficiency. 2-hour-annerobic, 6-hour-aerobic and 3-hour-anoxic operation during reaction period was found an effective operating method for organic and nitrogen removal from fish processing wastewater in SBR system. The average removal efficiencies of COD, BOD, and total nitrogen in SBR operated continuousely were 91%, 95%, and 67.1%, respectively. The estimated values of biomass yield coefficient(Y), microbial decay coefficient($K_d$), and bioreaction rate constant(K) were $0.35gMLSS/gCOD_{removed}$, $0.015day^{-1}$, and $0.209hr^{-1}$, respectively. As NaCl concentration increased from 5 to 30g/L, sludge settleability was cnhanced but organic removal in the reactor was decreased. NaCl of influent had considerable relationship with COD removal, whereas it did not significant affect nitrogen removal.

• Fisheries and Aquatic Sciences
• /
• 제15권1호
• /
• pp.9-14
• /
• 2012

The objectives of this research were to improve the film-forming properties of Channel Catfish Ictalurus punctatus skin gelatin (CSG) by cross-linking with transglutaminase (TG), determine and optimize the TG reaction time, and characterize the mechanical and barrier properties of CSG edible film. Cross-linking of CSG was performed by TG for 0, 10, 20, 30, and 40 min at $50^{\circ}C$, and the reaction was confirmed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). The color and mechanical and barrier properties of edible films fabricated with CSG cross-linked with TG were characterized. Gelatin yields from the extraction ranged from 18.2% to 23.3%. SDS-PAGE exhibited dark bands at 120 and 250 kDa, indicating successful TG-mediated cross-linking. The color of CSG film was not affected by TG cross-linking. The tensile strength of CSG films cross-linked with TG decreased from 42.59 to 21.73 MPa and the percent elongation increased from 42.92% to 76.96% as reaction times increased from 0 to 40 min. There was no significant difference in water vapor permeability of CSG films.

• 한국재료학회지
• /
• 제15권11호
• /
• pp.717-721
• /
• 2005

Silica powders were synthesized using emulsion solution containing water, nonionic surfactant of Triton N-57, and cyclohexane. Silica powders were prepared at low cost using inexpensive starting material of sodium silicate and ammonium sulfate. Morphology, size and size distribution were observed and determined using SEM. The powder was identified as silica by FT-IR and XRD analysis. Particle size and size distributions were affected by concentration of reactants, reaction time, and concentration of surfactant. Particle size were increased with increasing concentration of reactants and particles became dense with increasing reaction time. As R value increased, tile particle size was increased, reached a certain value and then decreased again. The silica powders synthesized under optimum condition were spherical in shape, $0.8{\mu}m$ in average particle size, narrow in particles size distribution, and well dispersed.

• Nuclear Engineering and Technology
• /
• 제41권6호
• /
• pp.785-796
• /
• 2009

A KALIMER-600 concept which is a type of sodium-cooled fast reactor, has been developed at KAERI. It uses sodium as a primary coolant and is a pool-type reactor to enhance safety. Also, a supercritical carbon dioxide ($CO_2$) Brayton cycle is considered as an alternative to an energy conversion system to eliminate the sodium water reaction and to improve efficiency. In this study, a simplified model for analyzing the thermodynamic performance of the KALIMER-600 coupled with a supercritical $CO_2$ Brayton cycle was developed. To develop the analysis model, a commercial modular modeling system (MMS) was adopted as a base engine, which was developed by nHance Technology in USA. It has a convenient graphical user interface and many component modules to model the plant. A new user library for thermodynamic properties of sodium and supercritical $CO_2$ was developed and attached to the MMS. In addition, some component modules in the MMS were modified to be appropriate for analysis of the KALIMER-600 coupled with the supercritical $CO_2$ cycle. Then, a simplified performance analysis code was developed by modeling the KALIMER-600 plant with the modified MMS. After evaluating the developed code with each component data and a steady state of the plant, a simple power reduction and recovery event was evaluated. The results showed an achievable capability for a performance analysis code. The developed code will be used to develop the operational strategy and some control logics for the operation of the KALIMER-600 with a supercritical $CO_2$ Brayton cycle after further studies of analyzing various operational events.

• 폴리머
• /
• 제38권1호
• /
• pp.16-23
• /
• 2014

A novel poly(AM-DMDAAC)/MMT superabsorbent nanocomposites are prepared by radical polymerization using ammonium persulfate (APS) and anhydrous sodium sulfite as a free radical initiator and N,N-methylene bisacrylamide (MBA) as a crosslinker. In this paper, an optimization study on the synthesis of superabsorbent nanocomposites is carried out. Orthogonal array experiment indicates that the optimized conditions is acrylamide (AM) content 23 wt%, diallyl dimethyl ammonium chloride (DMDAAAC) content 6 wt%, montmorillonite (MMT) content 4 wt%, initiator content 0.2 wt% and crosslinker content 0.02 wt%. Under the optimization syntheses conditions concluded, the maximum water absorbency in distilled water is $659.53g{\cdot}g^{-1}$ and in 2 wt% sodium chloride solution is $116.25g{\cdot}g^{-1}$. Compared with the range values of different factors ($R_j$), the order of significance factors in distilled water is C (MMT) > B (DMDAAC) > A (AM) > D (crosslinker) > E (initiator). MMT is intercalated during polymerization reaction and a nanocomposite structure is formed as shown by TEM analysis and XRD analysis.

• 한국수산과학회지
• /
• 제14권3호
• /
• pp.139-147
• /
• 1981

식품 방부제인 2-(2-furyl)-3-(5-nitro-2-furyl) acrylamide의 사용이 금지된 후로 어묵 및 어육햄(ham) 및 소시지(sausage) 등의 보존성을 높이기 위한 수단의 하나로 제품의 $a_w$치를 0.94이하로 떨어뜨리는 방법이 권장되고 있다. 본 연구에서는 포장 어묵을 제조할 때에 수분량을 일정하게 조정하여 식염, 당류 및 다가알코올류를 첨가하였을 경우 제품에 미치는 첨가제의 수분 활성저하 효과를 조사하였다. 1. 식염은 $4\%$이상 첨가하면 $a_w$를 0.94이하로 저하시킬 수 있었다. 그러나, 제품의 맛을 고려할 때 실용성이 없을 것으로 생각된다. 2. sucrose, lactose, maltose보다 g1ucese의 수분활성 저하 효과는 현저히 컸으나 갈변을 유발하므로 다량 첨가는 문제가 될 것으로 생각된다. 3. glycerin, sorbitol 및 propylene glycol 등의 다가알코올류는 대체로 수분 활성 저하 효과가 좋았다. 그 효과는 glycerin, propylene glycol, sorbitol의 순이었고, 특히 glycerin은 효과가 좋아서 식염의 1/3정도의 저하 효과가 있었다. 4. 동일 첨가제에 있어서는 제품의 수분함량이 저하 경우가 수분 활성 저하 효과가 다소 나은 경향을 보였다.

• 한국미생물·생명공학회지
• /
• 제18권1호
• /
• pp.35-38
• /
• 1990

정제된 저해물질의 Rf치는 0.12-0.71 사이였으며 melting point는 154.3-155.3$^{\circ}C$로 나타났다. 물, formic acid, ethylene glycol monomethyl ether에는 용해되지만 그외 대부분의 용매에서는 불용성이었고 흡습성이 매우 큰 물질이었다. Phenol-sulfuric acid, ninhydrin, silvernitrate-sodium hydroxide 반응은 양성이었으나, DNS 반응에서는 음성이며 자외선 조사하에서 형광을 나타내었다. 저해물질의 구성성분은 fructose와 aspartic acid로 확인되었으며 분자량이 약 1,050 정도였다.

• Environmental Engineering Research
• /
• 제24권3호
• /
• pp.376-381
• /
• 2019

In this study, a poly(vinyl) alcohol/sodium alginate (PVA/SA) mixture was used to fabricate core-shell structured gel beads for autotrophic single-stage nitrogen removal (ASNR) using aerobic and anaerobic ammonia-oxidizing bacteria (AAOB and AnAOB, respectively). For stable ASNR process, the mechanical strength and oxygen penetration depth of the shell layer entrapping the AAOB are critical properties. The shell layer was constructed by an interfacial gelling reaction yielding thickness in the range of 2.01-3.63 mm, and a high PVA concentration of 12.5% resulted in the best mechanical strength of the shell layer. It was found that oxygen penetrated the shell layer at different depths depending on the PVA concentration, oxygen concentration in the bulk phase, and free ammonia concentration. The oxygen penetration depth was around $1,000{\mu}m$ when 8.0 mg/L dissolved oxygen was supplied from the bulk phase. This study reveals that the shell layer effectively protects the AnAOB from oxygen inhibition under the aerobic conditions because of the respiratory activity of the AAOB.