• Journal of the Korean Chemical Society
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• v.56 no.5
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• pp.628-637
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• 2012

In this research, the textbook contents related to the ionization degree of strong acid in water were analyzed from 1945 year syllabus to chemistry II textbook in 2009 revised curriculum. Fifty chemistry teachers' cognition related to the species of strong acid in water, and the relationship between the degree of ionization was surveyed by a questionnaire and interviews. As results, most of the teachers thought the species of strong acid in water based on the degree of ionization represented on the chemistry II textbooks. They didn't recognize the conflict of the degree of ionization and definition of strong acid on the textbooks, and then they awakened the conflict, they could not solve the problem.

• Journal of the Korean Chemical Society
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• v.57 no.2
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• pp.279-288
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• 2013

In this study, we analyzed the values of ionization and ionization constants in the chemistry textbooks developed during 1945-2009 year. The chemistry teachers compared strength of strong acids in aqueous solution by questionnaire. In the questionnaire, we searched chemistry teachers' cognitions about the discordance reason of ionization constant formulation and the values in the textbooks. The subjects were 46 chemistry teachers. As results, the teachers compared the strength of strong acids in aqueous solution based on the ionization and ionization constant values in the textbooks. They didn't notice the problem of discordance of ionization constant formulation and the values in the textbooks. Even though they recognized the problem, they could not find the solution, and thought the problem arrived by experiment error or measurement error.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2006.04a
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• pp.166-170
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• 2006

본 연구에서는 폐광산 주변에 산재되어 있는 광미/광폐석을 처리하기 위하여 고형화 실증 실험을 수행하였다. 고형화 공정에서 흔히 사용하는 포틀랜드 시멘트와 MSG-E, MSG-N을 고화제로 사용하였으며 현장 광미 및 광폐석을 대상으로 고화체를 양생하고 고화체의 압축강도 및 중금속 용출 정도를 측정하였다. 고화체의 물리/화학적 특성을 비교하기 위해 광미/고화제 비율, 배합수/고화제 비율 그리고 고화체 양생기간을 실험인자로 설정하였다. 실험 결과 광미/고화제의 비율 1:1 만을 고려하더라도 중금속 용출의 급격한 감소가 이루어지는 것을 확인할 수 있었으며 광미/고화제의 비율을 3:1 이하로 유지시키는 경우, 고화체의 압축강도가 현행 폐기물 관리법(20조 관련)에서 규정하고 있는 차단형 매립시설 내부막의 압축강도 기준인 $0.21kgf/mm^2$ 보다 높은 것으로 나타났다. 다양한 pH를 갖는 수용액에 대하여 시간에 따른 고화체의 중금속 용출률을 측정한 결과, 수용액의 pH가 1과 13인 강산/강염기 용액에서 일부 중금속의 용출 농도가 지하수 생활용수 기준치를 초과하였으나, pH와 3 - 11인 경우에는 중금속 용출률이 급격히 감소하여 모두 기준치 이하를 나타내었다. 또한, pH가 1과 13인 수용액의 경우에도 고화체와 반응하는 시간이 증가할수록 고화체의 buffering 효과에 의해 수용액의 pH가 감소하였다. 이러한 결과는 현장에서 접촉수의 pH가 강산이나 강염기라 하여도, 고화체의 buffering 효과에 의해 시간이 지남에 따라 수용액의 pH가 낮아져 고화체로부터의 중금속 용출은 매우 감소할 것임을 의미한다.ss of an active application defined using the model. The technique is developed in a platform- and language-independent way, and it is algorithmic and can be automated by computer program. We give an example dealing with network auction to illustrate the use of the model and the verification technique.품으로 내부 온도분포를 측정하였으며, 유한차분법 프로그램으로 대류열전달계수를 결정하였다. 대류열전달계수는 792에서 2,107 W/m$^2$로 분석되었다. 대류열전달 계수는 액상식품과의 상대속도가 증가함에 따라서 증가하였고, 점도가 증가함에 따라서는 감소하였다.ce of precision/recall of 90.99%/92.52%, and 93.39%/93.41% respectively. 의한 변성에 부분적으로 보호 작용을 나타 낼 것으로 추정된다.경(製麴72時間頃)의 활성(活性)은 보리쌀국(麴), 밀가루국(麴), 찹쌀국(麴), 고구마국(麴)의 순이었다.험 결과 오전용 사료는 관행적인 산란계 배합사료에서 Ca공급제를 제외한 것을 급여하고, 오후용 사료는 Ca공급제를 3배 첨가한 T2처리로 15:00~16:00시에 교체급여를 하면 사료섭취량 감소와 사료비 절감면에서 바람직할 것으로 사료되며, 고에너지-고단백질-저Ca의 분말사료와 저에너지-저단백질-고Ca의 펠렛사료를 혼합급여하면 산란계의 사료

• Clean Technology
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• v.17 no.2
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• pp.156-165
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• 2011

The process for bioethanol production from lignocellulosic biomass was studied through process simulation using PRO/II. Process integration was conducted with concentrated acid pretreatment, hydrolysis process, SMB (simulated moving bed chromatography) process and pervaporation process. Energy consumption could be minimized by the heat recovery process. In addition, material and energy balance were calculated based on the results from the simulation and literature data. A net production yield of 4.07 kg-biomass and energy consumption value of 3,572 kcal per 1 kg ethanol were calculated, which is indicating that 26% yield increase and 30% energy saving compared to the bioethanol production process with dilute-acid hydrolysis (SRI report). In order to make it possible, sugar conversion yield of cellulose and hemi-cellulose is to be reached up to 90% and fermentation of xylose needs to be developed. In order to reduce the energy consumption up to 30%, the concentration of acid solution after being separated by 5MB should exceed 20%. If acid/sugar separation by SMB process is to be practical, the bioethanol process designed in this study can be commercially feasible.

• Applied Chemistry for Engineering
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• v.32 no.1
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• pp.20-27
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• 2021

Effects of the etching treatment of SAPO-34 catalyst were investigated to improve the catalytic lifetime in DTO reaction. The aqueous NH3 solution was a more appropriate treatment agent which could control the degree of etching progress, compared to that of using a strong acid (HCl) or alkali (NaOH) solution. Therefore, the effect on characteristics and lifetime of SAPO-34 catalyst was observed using the treatment concentration and time of aqueous NH3 solution as variables. As the treatment concentration or time of aqueous NH3 solution increased, the growth of erosion was proceeded from the center of SAPO-34 crystal plane, and the acid site concentration and strength gradually decreased. Meanwhile, it was found that external surface area and mesopore volume of SAPO-34 catalyst increased at appropriate treatment conditions. When the treatment concentration and time were 0.05 M and 3 h, respectively, the lifetime of the treated SAPO-34 catalyst was the longest, and was significantly enhanced by ca. 36% (based on DME conversion of > 90%) compared to that of using the untreated catalyst. The model for the etching progress of SAPO-34 catalyst in a mild treatment process using aqueous NH3 solution was also proposed.

• Applied Chemistry for Engineering
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• v.21 no.2
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• pp.188-194
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• 2010

The electrolyzed sterilizing water is useful functional aqueous solution, which is produced by electrolyzing aqueous solution. Electrolytic supplement such as salt or hydrochloric acid is added into tap water. Electrolyzed sterilizing water is classified as three types; strongly acidic electrolyzed water, weakly acidic electrolyzed water, and sodium hypochlorite water. In this study, preparation principles, advantages, and disadvantages of electrolyzed sterilizing water were analyzed. The technology trend in electrolyzed sterilizing water was analyzed based on patent application year, countries, main applicants, and each technologies.

• Resources Recycling
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• v.27 no.4
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• pp.44-49
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• 2018

$MoO{_4}^{2-}$ is the stable chemical species of Mo(VI) in alkaline solution. In the pH range of 2 to 6, condensation polymerization between $MoO{_4}^{2-}$ and hydrogen ion results in the formation of various polyanions of Mo(VI). Polycations of Mo(VI) begin to form when solution pH is less than 2. As the concentration of inorganic acid increases, polycations of Mo(VI) can react with the anion of the inorganic acid, resulting in the formation of heteranions of Mo(VI). The distribution of Mo(VI) species at pH < 6 depends on the concentration of Mo(V) and inorganic acid. In order to analyze the solvent extraction and ion exchange data on Mo(VI) from concentrated inorganic acid solution, it is necessary to elucidate the nature of Mo(VI) complexes.

• Resources Recycling
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• v.31 no.6
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• pp.25-35
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• 2022

The adsorption/desorption behavior and separation conditions of vanadium and tungsten ions were investigated using a gel-type anion-exchange resin. In the adsorption experiment with the initial acidity of the solution, the adsorption rate of vanadium was remarkably low in strong acids and bases. Additionally, the adsorption rate of tungsten was low in a strong base. An increase in the reaction temperature increased the adsorption reaction rate and maximum adsorption. The effect of tungsten on the maximum adsorption was minimal. The adsorption isotherms of vanadium and tungsten on the ion-exchange resin were suitable for the Langmuir adsorption isotherms of both the ions. For tungsten, the adsorption isotherms of vanadium and tungsten were polyoxometalate. Both ion-exchange resins were simulated using similar quadratic reaction rate models. Vanadium was desorbed in the aqueous solutions of HCl or NaOH, the desorption characteristics of vanadium and tungsten depended on the desorption solution, and tungsten was desorbed in the aqueous solution of NaOH. It was possible to separate the two ions using the desorption process. The desorption reaction reached equilibrium within 30 min, and more than 90% recovery was possible.

• Korean Journal of Food Science and Technology
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• v.38 no.6
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• pp.742-750
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• 2006

This study was carried out to investigate the efficacy of two kinds of electrolyzed water with added 0.5% (v/v) citron juice, SAEW-CJ[Strong Acidic Electrolyzed Water with added Citron Juice, pH 2.57, ORP (oxidation-reduction potential) 1,122 mV, HClO 23.05ppm] and LAEW-CJ (Low Alkaline Electrolyzed Water with added Citron Juice, pH 4.67, ORP 997mV, HClO 42.55mV) as storing liquid for peeled taro. During storage at $5^{\circ}C$ until 30 days, SAEW-CJ and LAEW-CJ inhibited the growth of microorganisms more effectively than 0.2% (w/v) APS (aluminium potassium sulfate) and 0.85% (w/v) NaCl did. Total phenolic contents, PRO (polyphenol oxidase) activity, color differences value (${\Delta}E$) and vitamin C contents of peeled taro stored in SAEW-CJ and LAEW-CJ were lower than those stored in 0.2% APS and 0.85% NaCl. The hardness decrement of peeled taro stored in LAEW-CJ was lower than that of the others. In addition, the contents of moisture, crude protein, crude ash, total sugars, and reducing sugars were gradually decreased during storage. However, no difference by peeling methods or immersion liquid was found.

• Clean Technology
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• v.18 no.4
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• pp.446-450
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• 2012

Strong alkaline electrolyzed water which is produced in cathode by electrolyzing the solution where electrolytes (NaCl, $K_2CO_3$ etc.) are added in diaphragm electrolytic cell, is eco-friendly and has cleaning effects. So, it is viewed as a substitution of chemical cleaner. In addition, strong alkaline electrolyzed water is being used by some Japanese automobile and precision parts manufacturing industries. When strong alkaline electrolyzed water is produced by using diaphragm electrolytic cell, it is necessarily produced at the anode side. Since strong acidic electrolyzed water produced is discarded when its utilization cannot be found, production efficiency of electrolyzed water is consequently decreased. Also, there is a weakness electrolytic efficiency is decreasing due to the pollution of diaphragm. In order to overcome this, non-diaphragm all-in-one electrolytic cell integrated with electrode reaction chamber and dilution chamber was applied. Strong alkaline electrolyzed water was produced for different composition of electrolytes, and their properties and characteristics were identified. In comparing the properties between strong alkaline electrolyzed water produced in diaphragm electrolytic cell and that produced in all-in-one electrolytic cell, the differences in ORP and chlorine concentration were found. In emulsification test to confirm surface-active capability, similar results were obtained and strong alkaline electrolyzed water produced in non-diaphragm all-in-one electrolytic cell was identified to be useable as a cleaner like strong alkaline electrolyzed water produced in diaphragm electrolytic cell. Strong alkaline electrolyzed water produced in non-diaphragm all-in-one electrolytic cell is thought to have sterilizing power because it has active chlorine which is different from strong alkaline electrolyzed water produced in diaphragm electrolytic cell.