• Journal of Conservation Science
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• v.37 no.3
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• pp.282-288
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• 2021

This basic research was conducted to support the development of woodcraft bio-adhesives using peach gum, which is the resin produced by peach trees. The synthesis conditions of these adhesives were optimized by performing 144 experiments. The application potential of peach gum adhesives was explored by comparing their properties with those of three natural adhesives and four synthetic adhesives. The best adhesive strength was obtained by dissolving the resin in 80 mL of distilled water containing 1.5 g NaOH, 1.65 g H₂O₂ ( pH 8.0-9.0), 0.5 g NaClO, and 0.5 g H₂BO₂. The adhesive strength, which showed minimal changes and excellent reversibility, was 125.39 kgf/cm². Ultraviolet radiation-mediated deterioration in strength in the absence of total aerobic bacteria was negligible (△E^*ab = 2.75). These data confirm the potential value of peach gum-based bio-adhesives for woodcraft as well as their utility as alternatives for natural and synthetic adhesives used for the manufacture and restoration of handicrafts and preservation of cultural assets.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.12
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• pp.362-368
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• 2020

In this study, the gallic acid content of various varieties of chestnuts (Daebo, Okgwang, Chukpa, Samjosaeng) was investigated during the period between May 2018 to July 2019. A quantitative analysis was performed by HPLC using extracts of chestnut, inner skin, outer skin, branches, chestnut, male flower, and the male flower for each type of chestnut tree. Gallic acid was identified by dissolving standard gallic acid in water and analyzed three times in the concentration range of 100, 200, 250, and 500ppm. Linearity was confirmed by the peak area ratio at each concentration. Among the different chestnut varieties, the gallic acid content was highest at 0.0863% in Chukpa, followed by Daebo, Okgwang, and Samjosaeng. While comparing the average gallic acid content of each part of the chestnut tree, it was observed that the falling male flower had the highest content at 1.2100%, followed by chestnut leaves, chestnut pines, and branches. In a comparison of the inner skins, the Daebo variety had the highest gallic acid content at 0.7463% followed by Chukpa, Okgwang, and Samjosaeng. The outer skin of Samjosaeng had the highest content at 0.4918%, followed by Chukpa, Daebo, and Okgwang. The pines of the Samjosaeng chestnut had the highest content at 1.3035%, followed by Daebo, Chukpa, and Okgwang.

• Journal of the Korean Society of Food Science and Nutrition
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• v.34 no.5
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• pp.707-714
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• 2005

Ingredient ratio for making nabak kimchi and the manufacturing method were standardized from the available literatures. Fermentation properties and $CO_2$ production of the nabak kimchi were investigated during the fermentation at $5^{\circ}C,\;10^{\circ}C,\;and\;20^{\circ}C$. Standardized ingredients ratio of nabak kimchi that added 100 mL of water was as follows: 45.0 g baechu cabbage, 26.9 g radish, 1.9 g green onion, 1.0 g red pepper, 1.2 g crushed garlic, 0.9 g crushed ginger, 0.7 g red pepper powder. The standardized manufacturing method of nabak kimchi was as follows: washing ingredients, cutting radish and baechu cabbage $(2.5\times2.5\times0.5\;cm)$, salting for 20 min, washing and draining, pretreatment of ingredients, dissolving red pepper powder in water, blending, mixing, and adding the water to the mixed ingredients. Fermentations at $5^{\circ}C$ for 8 days, at $10^{\circ}C$ for 3 days, and at $20^{\circ}C$ for 1 day led to the acidity levels of $0.21\%,\;0.20\%,\;and\;0.31\%$, respectively. From the relationships between optimally ripened pH and acidity, nabak kimchi showed lower acidity of $0.20\~0.25\%$ with pH $4.2\~4.5.$ Like other kinds of kimchi, the Levels of Leuconostoc sp. were high specially at later stage of fermentation at low temperature $(5^{\circ}C)$. However, the levels of Lactobacillus sp. were low at $5^{\circ}C$. Nabak kimchi produced high levels of $CO_2$ in the initial fermentation period and followed by rapid decrease of $CO_2$ production with the fermentation. From the relationships between pH and $CO_2$ content, the highest $CO_2$ contents were found pH $4.0\~4.4$, 3.8 and 3.4 at $5^{\circ}C,\;10^{\circ}C$, and $20^{\circ}C$, respectively. This fact indicated that fermentation at $5^{\circ}C$ has the highest $CO_2$ content at optimally ripened pH of 4.3 and the fermentation at lower temperature such as $5^{\circ}C$ could extend the eatable time of nabak kimchi.

• Resources Recycling
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• v.32 no.3
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• pp.26-37
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• 2023

Good control of the solution pH and temperature is required to recover vanadium from the water leaching solution of vanadium ore after sodium roasting. However, such adjustments could lead to aluminum-vanadium and sodium-vanadium co-precipitation, which greatly affects the efficiency of vanadium recovery. In this study, a process that can increase the efficiency of vanadium recovery as ammonium metavanadate [NH₄VO₃] and ammonium polyvanadate [(NH₄)₂V₆O₁₆·H₂O] was investigated by examining the characteristics of vanadium-containing aqueous solutions during precipitation. The aluminum content of vanadium-containing water leaching solutions has a great effect on the loss of vanadium when the pH of the aqueous solution is adjusted to 9. Therefore, a process to minimize aluminum leaching is also required. In this study, ~99% or more of vanadium present in vanadium-containing aqueous solutions was precipitated and recovered as NH₄VO₃ by adding 3 equivalents of ammonium chloride relative to the vanadium content at pH 9 and room temperature. (NH₄)₂V₆O₁₆·H₂O was precipitated from the aluminum-vanadium coprecipitates generated during the pH-adjustment of the aqueous solutions to 9 by dissolving the coprecipitate in the solutions at pH 2.5 and controlling their sodium content to 2,000 mg/L or less. Approximately, 98% or more of the available (NH₄)₂V₆O₁₆·H₂O could be precipitated and recovered from a solution with a vanadium content of 2,200 mg/L and a sodium content of 1,875 mg/L at pH 2.5 by adding approximately 3 equivalents of ammonium chloride relative to the vanadium content at 95℃ or higher. The overall process could precipitate and recover, approximately 91% or more of the total vanadium in the water leaching solution as NH₄VO₃ and (NH₄)₂V₆O₁₆·H₂O.

• Journal of the Korean Society for Marine Environment & Energy
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• v.16 no.1
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• pp.9-16
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• 2013

An experiment was conducted to evaluate the biochemical adverse effect of increased carbon dioxide in seawater on marine polychaete, Perinereis aibuhitensis. We measured the available energy reserves, Ea (total carbohydrate, protein, and lipid content) and the energy consumption, Ec (electron transport activity) of Perinereis aibuhitensis exposed for 7-d to a range of $CO_2$ concentration such as 0.39 (control =390 ppmv), 3.03 (=3,030 ppmv), 10.3 (=10,300 ppmv), and 30.1 (=30,100 ppmv) $CO_2$ mM, respectively. The cellular energy allocation (CEA) methodology was used to assess the adverse effects of toxic stress on the energy budget of the test organisms. The results of a decrease in CEA effect of increased carbon dioxide in seawater from all individual in Ea and Ec. Increase of carbon dioxide reduced pH in seawater, significantly. The chemical changes in sea- water caused by increasing $pCO_2$ might cause stresses to test organisms and changes in the cellular energy allocations. Results of this study can be used to understand the possible influence of $CO_2$ concentration increased by the leakage from sub-sea bed storage sites as well as fossil fuel combustion on marine organisms.

• Journal of the Korean Electrochemical Society
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• v.17 no.2
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• pp.111-118
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• 2014

The electrochemical properties using the cells assembled with the synthesized $LiCoO_2$(LCO) were evaluated in this study. The LCO was synthesized from high-purity cobalt sulfate($CoSO_4$) which is recovered from the cathode scrap in the wastes lithium ion secondary battery(LIB). The leaching process for dissolving the metallic elements from the LCO scrap was controlled by the quantities of the sulfuric acid and hydrogen peroxide. The metal precipitation to remove the impurities was controlled by the pH value using the caustic soda. And also, D2EHPA and $CYANEX^{(R)}272$ were used in the solvent extraction process in order to remove the impurities again. The high-purity $CoSO_4$ solution was recovered by the processes mentioned above. We made the 6 wt.% $CoSO_4$ solution mixed with distilled water. And the 6 wt.% $CoSO_4$ solution was mixed with oxalic acid by the stirring method and dried in oven. $LiCoO_2$ as a cathode material for LIB was formed by the calcination after the drying and synthesis with the $Li_2CO_3$ powder. We assembled the cells using the $LiCoO_2$ powders and evaluated the electrochemical properties. And then, we confirmed possibility of the recyclability about the cathode materials for LIBs.

• Journal of Bio-Environment Control
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• v.22 no.1
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• pp.65-72
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• 2013

This study was conducted to investigate the influences of bicarbonate ($HCO_3^-$) concentrations in irrigation solution on growth of lettuce and change in chemical properties of root media. The blue leaf and red leaf lettuces with two true leaf stages were transplanted into 10 cm diameter plastic pots filled with perlite. The five treatments were made by dissolving $NaHCO_3$ into irrigation solution to reach 30, 70, 110, 150 and $180mg{\cdot}L^{-1}$ $HCO_3^-$. The crops were fed with fertilizer solution contained $HCO_3^-$ with various concentrations and controlled to $100mg{\cdot}L^{-1}$ in nitrogen concentration. The pH in soil solution of root media 10 weeks after transplant of blue lettuces were 7.04 and 7.10 in the treatments of 30 and $70mg{\cdot}L^{-1}$ of $HCO_3^-$, respectively. But those rose gradually after week 3 and finally reached 7.39, 7.48 and 7.56 at week 10 in the treatments of 110, 150 and $180mg{\cdot}L^{-1}\;HCO_3^-$, respectively. The pH in the treatments of 30 and $70mg{\cdot}L^{-1}\;HCO_3^-$ in cultivation of red leaf lettuce were around 6.65 during week 4 to week 8, but this rose abruptly and reached 6.92 and 7.01 at week 10, respectively. Those in the treatments of 110, 150, and $180mg{\cdot}L^{-1}\;HCO_3^-$ rose gradually and finally reached to 7.49, 7.53, and 7.58, respectively. The EC rose gradually after week 2 in all treatments of blue and red leaf lettuces. The change of macro ion concentrations in both blue and red leaf lettuces showed similar trends. The concentrations of $PO_4-P$, $Ca^{2+}$ and $Mg^{2+}$ increased gradually in all treatments of $HCO_3^-$ during cultivation of blue and red leaf lettuces. As the concentrations of $HCO_3^-$ in irrigation solution were elevated, the concentrations of $PO_4-P$, $Ca^{2+}$ and $Mg^{2+}$ became higher and that of ${SO_4}^{-2}$ became lower in soil solution of root media. The main reason of concentration changes were that $HCO_3^-$ influenced pH and the pH changes also affect the activities of the ions in soil solution of root media.

• The Korean Journal of Nuclear Medicine Technology
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• v.16 no.2
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• pp.139-148
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• 2012

Purpose : Since standard solution is the one that knows its exact concentration, the curve of the dissolution has been determined according to the amount of the solution, compared to the amount of the unknown sample. Therefore, the antigen that makes up standard materials should be made in a pure form. The configuration of the standard substance solution in the kit we use is a freeze-dried material, or made and comes as a liquid. Lyophilized reference material is used after dissolving in usually D.W. (Distilled Water), and if the antigen to use is too sensitive, reagents should be freeze-dried. Furthermore, when freeze-dried reference has to be frozen again after being dissolved, it should be kept under $-20^{\circ}C$ until the expiration date according to the reports. Since it is not expressed in the experiment if it is safe or stable to reuse the solution which was dissolved a few times, thus, this time it is tested and evaluated that the changes of the standard solution by freezing and melting several times, and its results and the effectiveness of it were compared to the solution which was kept in a fridge. Materials and Methods : Among Vitro diagnostic kits on the market made by radioimmunoassay, parathyroid hormone (PTH), adrenocorticotropic hormone (ACTH), luteinizing hormone (LH) are made of freeze-dried standard solution and all composed of the same Lot.NO. These hormones melted in D.W. and were separated into three groups. In the first group, melting and freezing were repeated, and in the second group, The solution only for one time use was put into a test tube after melting and freeze it. The third group was kept in the refrigerator. This experiment has been conducted from January to February in 2012. January to 2012. PH test was employed because ph is prone to changing depending on the change of protein. Each group of the standard solution, cpm (counter per minute), and the patient relative concentration values were compared by date, and Through the correlation coefficient and Paired t-test, the significant level of each group was analyzed. Results : ACTH, PTH, LH pH values were too subtle denaturation rather than numerical changes in the protein. In addition, when the standard solution of ACTH, PTH, LH was refrigerated, after 3 days and 7 days, there was a significant difference observed between the solution being kept in a refrigerator and a freezer within a significance level. Conclusion : Standard solution should be kept in a freezer, and being kept in a fridge, it is recommended to use the solution as soon as possible.

• Restorative Dentistry and Endodontics
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• v.34 no.1
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• pp.42-50
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• 2009

Deterioration of long-term dentin adhesion durability is thought to occur by hydrolytic degradation within hydrophilic domains of the adhesive and hybrid layers. This study investigated the hypothesis that priming the collagen network with an organic solvent displace water without collapse and thereby obtain good bond strength with an adhesive made of hydrophobic monomers and organic solvents. Three experimental adhesives were prepared by dissolving two hydrophobic monomers, bisphenol-A-glycidylmethacrylate (Bis-GMA) and triethyleneglycol dimethacrylate (TEGDMA), into acetone, ethanol or methanol. After an etching and rinsing procedure, the adhesives were applied onto either wet dentin surfaces (wet bonding) or dentin surfaces primed with the same solvent (solvent-primed bonding). Microtensile bond strength (MTBS) was measured at 48 hrs, 1 month and after 10,000 times of thermocycles. The bonded interfaces were evaluated using a scanning electron microscope (SEM). Regardless of bonding protocols, well-developed hybrid layers were observed at the bonded interface in most specimens. The highest mean MTBS was observed in the adhesive containing ethanol at 48 hrs. With solvent-primed bonding, increased MTBS tendencies were seen with thermo cycling in the adhesives containing ethanol or methanol. However, in the case of wet bonding, no increase in MTBS was observed with aging.