• Clean Technology
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• v.25 no.3
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• pp.189-197
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• 2019

In this study an optimization of the preparation conditions of activated carbon with a ternary metal ion material to treat $H_2S$, which is classified as a representative odor substance, was carried out. For a metal ion material for enhancing the adsorption performance of hydrogen sulfide, performance enhancement was confirmed by combining Li and Fe or a ternary combination (K, Li, Fe) based on KI, which is a substance promoting hydrogen sulfide adsorption performance. Also, it was determined by XRD analysis that the reaction of each active substance with $H_2S$ was because of binding. The adsorption performance increased more than 3 times with heat treatment of the adsorbent with nitrogen compared with heat treatment with air. The maximum adsorption constant ($q_m$) value of the optimum adsorbent was 97.07, which is 6 times higher than that of the existing K-based impregnated activated carbon. It was confirmed that the objective adsorption amount ($0.3g\;g^{-1}$) was secured by an equilibrium between the mass transfer rate and adsorption rate. From the results, it was confirmed that the performance improvement was noticeable even when activated carbon with a reagent grade activated carbon particle size was modified. It was confirmed that the adsorption performance exists at high relative humidity levels of 60 and 100%, and the optimized preparation can be applied to a wet process such as a scrubber downstream.

• Current Research on Agriculture and Life Sciences
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• v.30 no.2
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• pp.61-67
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• 2012

In this study, hydroxypropyl methylcelluloses (HPMCs) were added to prepare the rice noodle and the effects of water dosage, HPMC content, and viscosity level of HPMC on the noodle-making properties of rice dough were examined. As the water dosage was increased, the rice dough after roller pass became more flat and homogeneous. However, when the water dosage was over a certain range, the rice noodle became more waved. In the test result of various HPMC contents, 3% HPMC addition was turned out to be an optimum condition for the best noodle-making properties of rice dough. As the viscosity level of HPMC decreased, the rice dough after roller pass became inhomogeneous. However, the lowest viscosity level HPMC (PMC 40H) did not show any waved rice noodle at even high water dosage indicating the improved noodle-making properties of rice dough. On the whole, it seems that 56~58% water dosage, 3% HPMC content, and high viscosity HPMC (PMC60U) were the optimum condition for preparation of good rice noodle.

• Resources Recycling
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• v.28 no.5
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• pp.60-67
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• 2019

A valuable metal recovery from waste resources such as spent rechargeable secondary batteries is of critical issues because of a sharp increase in the amount of waste resources. In this context, it is necessary to research not only recycling waste lithium-ion batteries (LIBs), but also reusing valuable metals (e.g., Li, Co, Ni, Mn etc.) recovered from waste LIBs. In particular, the lithium hydroxide ($LiOH{\cdot}xH_2O$), which is of precursors that can be prepared by the recovery of Li in waste LIBs, can be reused as a catalyst, a carbon dioxide absorbent, and again as a precursor for cathode materials of LIB. However, most studies of recycling the waste LIBs have been focused on the preparation of lithium carbonate with a recovery of Li. Herein, we show the preparation of high purity lithium hydroxide powder along with the precipitation process, and the systematic study to find an optimum condition is also carried out. The lithium carbonate, which is recovered from waste LIBs, was used as starting materials for synthesis of lithium hydroxide. The optimum precipitation conditions for the preparation of LiOH were found as follows: based on stirring, reaction temperature $90^{\circ}C$, reaction time 3 hr, precursor ratio 1:1. To synthesize uniform and high purity lithium hydroxide, 2-step precipitation process was additionally performed, and consequently, high purity $LiOH{\cdot}xH_2O$ powder was obtained.

• The Korean Journal of Malacology
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• v.21 no.1
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• pp.25-31
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• 2005

The embryos of marine bivalves have been commonly used in bioassays for the quality assessment of marine environments. Although several standard protocols for developmental bioassay with bivalves have been already proposed, there have been few trials for applying these protocols in environmental assessment, or for developing new protocol with Korean species. So, there is a strong need to establish the standard bioassay protocols using bivalves commonly found in Korean waters. Prior to developing a new protocol, it is essential to know the optimum conditions for the reliable bioassay procedures. Here, we established the purpose of this study to determine the optimum bioassay conditions for successful development of a common mussel, Mytilus galloprovincialis. The conditions considered as critical for developmental bioassay, and determined in this study were; (1) temperature, (2) salinity, and (3) initial density of embryo. The optimal temperature for developmental bioassay of M. galloprovincialis was determined as $15^{\circ}C$. At this temperature, the required time for the embryo to become veliger larva was 48 hr. The acceptable range of salinity for the embryotoxicity test using M. galloprivincialis was from 30 to 35 psu, which was narrower than that of the natural habitat of adult populations. The optimum density of embryo at the beginning of bioassay was 100 embryos/ml. Over this density, the proportion of normally developed larvae decreased significantly. The results obtained in this study will serve as a basis for preparation of the standard bioassay protocol using embryo of M. galloprovincialis.

• Analytical Science and Technology
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• v.13 no.2
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• pp.208-214
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• 2000

The formation and dissolution of hydroxides, carbonates and hydroxyapatite (HAp), which depend on the pH of solution, are important factor for the preparation of homogeneous and fine HAp, $Ca_{10-x}(HPO_4)_x(PO_4)_{6-x}(OH)_{2-x}(x=0)$, ceramic powder from the $Ca-PO_4-H_2O$ system. Since the solubility of each complex ion is a linear function of pH, the solubility diagram can be obtained by plotting the logarithmic molar concentrations calculated from the values of the equilibrium constants and solubility products for hydroxides, carbonates, and hydroxyapatite. The optimum pH condition for the formation of single phase $Ca_{10-x}(HPO_4)_x(PO_4)_{6-x}(OH)_{2-x}(x=0)$ powder in $Ca-PO_4-H_2O$ system at $25^{\circ}C$ was estimated as $10.5{\pm}0.5$ through the theoretical consideration. The HAp powder dried at $80^{\circ}C$ showed a fine agglomerated particles with a size of 75 nm. The HAp powder calcined at $1,000^{\circ}C$ consisted of nearly homogeneous particles with a size of 450 nm. Even though the dried HAp particles consisted of agglomeration, mechanical properties were superior due to fine microstructure after sintering.

• Journal of the Korean Society of Clothing and Textiles
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• v.29 no.7 s.144
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• pp.997-1007
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• 2005

The textile finishing methods utilizing chitosan have been mostly focused on the applications in the improvement of the dyeing of cotton fabrics, or the improvement of hand of the cotton or wool fabrics. On the other hand, it Is difficult to find the application examples in the synthetic fiber fabrics including polyester and nylon fabrics. The aim of this study is to improve the stiffness and the poor wash fastness of the fabrics treated only with chitosan. We tried to improve the softness by employing chitosan and polyurethane mixture solution and to prevent the detachment of the chitosan from the fabric. The treatment was applied to cotton, polyester, and nylon fabrics. The change of the properties of the treated fabrics were investigated. The optimum finishing condition was sought by changing the mixture ratio of the chitosan/PU(polyurethane) solutions. The adjusted ratios of the chitosan/PU solutions were 1 : 0, 1 : 0.25, 1 : 0.5, and 1 : 2 during the mixture solution preparation. Using the KES(Kawabata Evaluation System), the physical and mechanical properties of the finished fabric specimens were analyzed, and hand values of the specimens were calculated through the use of translational formulas. According to the chemical composition of the fibers, chitosan solution or chitosan/PU mixture exhibited wide range of coating effect. Since the chitosan acid solution has high polarity, the bonding force with the cotton fibers is high. By the appropriate addition of PU in the chitosan treatment of cotton, KOSHI and HARI values of the fabric improved. The air permeability of the chitosan/PU treated cotton fabric specimen improved, resulting in the highest value at the mixture of chitosan : PU=1:0.25.

• Fisheries and Aquatic Sciences
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• v.7 no.2
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• pp.51-57
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• 2004

Total phosphorus contents in rice bran and soybean meal were determined to be 5.81 and $2.77\%$, respectively, and $97.2\%$ of phosphorus in rice bran and $66.4\%$ in soybean meal were presented as phytate phosphorus. Optimum pH condition for hydrolysis of phytate in rice bran and soybean was determined to be in the pH range of 3.7 and 5.3. The highest activity of phytase for hydrolysis of phytate in both samples was determined to be at $55^{\circ}C$ for rice bran and $55-60^{\circ}C$ for soybean. Hydrolysis of phytate in soybean meal at pH 5.0 increased with the co-reaction or consecutive reaction with protease; however, in rice bran hydrolysis decreased with co-reaction with protease. Phytate degradation of soybean meal in the presence of pepsin at pH 2.5 showed higher than that of rice bran. Phytate degradation of rice bran in the presence of trypsin or pancreatin at pH 7.0 increased the activity around 2-times compared with the activity in the absence of trypsin or pancreatin. The results of this study suggest that hydrolysis of phytate in rice bran or soybean meal with phytase and protease may provide an alternative process for the preparation of aquacultural feed with a low level of organic phosphorus.

• The Korean Journal of Mycology
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• v.16 no.3
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• pp.128-134
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• 1988

For the preparation of fermented feed with Lyophyllum decastes, optimum cultural conditions for the production of cellulase were $30^{\circ}C$, pH 6.0, 60-70% moisture content and the cultural of 15 days. Among the submaterial added, 30-40% of rice bran and 0.72% of $(NH_4)_2PHO_4$ were effective for the cellulase production and its production increased when rice straw treated with 4% alkaline peroxides. Solid state fermentation of rice straw with Lyophyllum decastes for 40 days removed 19.9% of lignin, and increased the total nitrogen content to 1.6% from 1.1%. As the fermentation proceeded, the in vitro dry matter digestibility of fermented feed was increased and it increased 21.1% after 35 days.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.28 no.3
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• pp.331-337
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• 1995

Seaweed Jellys(Muks) were prepared with sea mustard and sea tangle. Optimum storage condition was also investigated in terms of bacterial counts, pH, titratable acidity, gel strength and total volatile nitrogen(TVN) as soaking temperature and time in distilled water. Gel strength of Muk decreased, and TVN and baterial counts increased during storage in water. Seaweed Muk has a shelf life of 3 days at $32^{\circ}C$ in water and 15 days at $18^{\circ}C$. Shelf life of seaweed Muk with soy milk was 3 days at 18's and shorter than that of seaweed Muk without soy milk.

• Journal of the Korean Ceramic Society
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• v.44 no.6 s.301
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• pp.325-330
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• 2007

High porous AlO(OH) gel is used in precursor of ceramic material, coating material and porous catalyst. For use of these, not only physiochemical control for particle morphology, pore characteristic and peptization but also studies of synthetic method for preparation of high porous AlO(OH) gel were required. In this study, high porous AlO(OH) gel was prepared through the aging and filtration process of aluminum hydroxides gel precipitated by the hydrolysis reaction of $Na_2CO_3$ solution and $Al_2(SO_4)_3$ and $Na_2SO_4$ mixed solution. In this process, optimum synthetic condition of AlO(OH) gel having excellent pore volume as studying the effect of hydrolysis pH on gel precipitates has been studied. Hydrolysis pH brought about numerous changes on crystal morphology, surface area, pore volume and pore size. Physiochemical properties of gel were investigated as using XRD, TEM, TG/DTA, FT-IR and $N_2$ BET method.