• Korean journal of food and cookery science
• /
• v.13 no.1
• /
• pp.78-85
• /
• 1997

To determine the optimum coagulants concentrations for preparing soybean-curds, the transmittance of soybean-curd whey using spectrophotometer has been measured. The textural properties of soybean-curds were examined by texture analyzer and sensory evaluations. The general components, oligosaccharides and amino acids in soybean-curd wheys were analyzed. Protein patterns of soybean-curd wheys comparing with soyflour and soymilk were investigated. By texture analyzer, hardness, cohesiveness, springiness, and gumminess of Cacl$_2$ soybean-curd, MgCl$_2$ soybean-curd were higher than those of CaSO$_4$ soybean-curd and GDL soybean-curd. In the sensory evaluations, CaSO$_4$ soybean-curds and GDL soybean-curds were smoother and moister than others. Glutamic acid and aspartic acid were the first two abundant amino acids in three kinds of soybean-curd wheys, but arginine was the most abundant amino acid in GDL soybean-curd whey. Total sugar content of soybean-curd wheys were about 12-13 g/l, and the main sugars among 5 kinds of sugars were sucrose and raffinose. Electrophoresis using SDS-PAGE showed that glycinin and P-conglycinin, the main proteins of soybean appeared in soy flour and soymilk, and only low molecular weight subunits appeared in soybean-curd wheys.

• Clean Technology
• /
• v.3 no.2
• /
• pp.87-93
• /
• 1997

A new process has been developed for nitrate and other salts removals from polluted waters. Alumina cement and calcium oxide served as precipitating agents to remove nitrate with stirring at basic pH. Low content of alumina in the commercialized alumina cements resulted in a increasing in nitrate removal yield. It is found that the compositions of aluminium and calcium are the most important factors in successful nitrate insolubilization. In order to remove high concentration of nitrate in polluted water, multi-stage precipitation was found to be very effective. Sulfate, chloride, and phosphate ions as well as nitrate were also removed by the precipitated reaction. After precipitation, post-treatments including Na2CO3 addition and neutralization with acid alleviated the level of aluminium and calcium in the treated water.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.10 no.1
• /
• pp.177-185
• /
• 2009

In this study, we developed the program to calculate the corrosion evaluation index for examining the corrosivity of raw water. When it was applied to the Han river and Nakdong river system, sulfuric acid ion, which accelerated corrosion, was higher in Nakdong river system than Han river system while calcium and hardness, which restrained corrosion, was the same way. Summarization of the LI and CCPP calculation result by the developed corrosion evaluation model showed that water quality of Han river system had strong tendency to corrode (is strongly corrosive). Moreover, this study evaluated the corrosivity of calcium carbonate saturation index by adding the chemicals to tap water. Saturation status was maintained in the order of $Ca(OH)_2$ > NaOH > ${Na_2}{CO_3}$ > $CaCO_3$ in the case of LI and RI.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
• /
• 2004.04a
• /
• pp.413-416
• /
• 2004

매립장 침출수로 인해 오염된 매립장 주변 지하수 정화를 위한 실내실험을 실시하였다. 오염물로는 대표적 염화용제인 TCE와 PCE, 그리고 중금속인 As, Cd, Cr, Pb에 대하여 Air-sparging, 오존 산화법, 화학적 처리방법에 의한 정화효율 실험을 실시하였다. Air-sparging은 TCE, PCE에서 높은 제거효율을 가졌으며, 오존 산화법은 Cr, Pb에서 제거 효율이 좋았다. 반응제를 첨가한 공침방법의 경우, 모든 중금속에 대하여 소석회 첨가시 매우 높은 제거효율을 보였으며, As는 황산제일철에서, Cd, Cr, Pb는 탄산칼슘과 제올라이트 첨가시 높은 제거효율을 나타내었다. 실험결과로부터, 유기오염물과 중금속이 혼합되어 나타나는 매립장 주변 오염 지하수의 경우 휘발성 유기오염물의 제거를 위해서는 폭기방법이, 중금속의 경우에는 공침방법에 의해 수산화물, 탄산염으로 만들어 고형물로 처리하는 방법이 제거효과가 좋은 것으로 나타났다.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2006.05b
• /
• pp.217-220
• /
• 2006

This paper describes a study undertaken to determine the effect of ground calcium carbonate(GCC) cement mortar with respect to sulfate attack. It were investigated visual appearance and expansion of cement mortars with GCC immersed in artificial solution of 5% sodium sulfate during 510days. According to increasing replacement of GCC, the expansion ratio was comparatively superior to GCC0 mortar specimen. The test results indicated that cement mortars with GCC was benefit the resistance of sulfate attack due to micro filler effect.

• Journal of the Korean Ceramic Society
• /
• v.33 no.12
• /
• pp.1331-1338
• /
• 1996

In order to investigate the reaction in the system of fly ash-sulfuric acid-calcium hydroxide the hydrates were produced by the addition of Ca(OH)2 to fly ash activated with sulfuric acid at various temperatures. And then they were characterized by XRD. SEM and TG-DTA. It was found that in the reaction of fly ash with sulfuric acid fly ash was not decomposed but Al2O3 and SiO2 component in it were activated. The addition of calcium hydroxide into this system resulted in the formation of ettringite and calcium silicate hydrate (C-S-H) As the concentration of sulfuric acid and reaction temperature increased the amount of calcium hydroxide decreased fast. At this time gypsum produced by the reaction calcium hydroxide with sulfuric acid was consumed to form ettringite. Accordingly the formation of ettringite increased with calcium hydroxide and reaction time. And it showed faster than the formation of C-S-H.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2008.11a
• /
• pp.385-388
• /
• 2008

Recycled fine aggregate has low quality because it contains large amount of old mortar. So, its usage is limited to a lower value-add, such as the roadbed material etc. Also, alkaline water occurred from treatment process of the waste concrete is becoming the cause of environmental problem. Accordingly, this study is to develop on the high quality recycled fine aggregate produced by low speed wet abraser using sulphuric. We investigated the properties of compressive strength of the mortar which was manufactured using recycled fine aggregate containing calcined gypsum produced by earlier mentioned process. Test results indicate that concrete using recycled fine aggregate containing calcined gypsum is higher compressive strength than concrete using other sands.

• Journal of the Korea Concrete Institute
• /
• v.17 no.4 s.88
• /
• pp.499-504
• /
• 2005

Polymer concrete shows excellent mechanical properties and chemical resistance compared with conventional normal cement concrete. The polymer concrete Is drawing a strong interest as high-performance materials in the construction industry Resins using recycled PET offer the possibility of a lower source cost of materials for making useful polymer concrete products. Also the recycling of PET in polymer concrete would help solve some of the solid waste problems Posed by plastics and save energy. An objective of this paper is to estimate the damage of sulfuric acid, through investigating recycled PET polymer concrete, immersed at sulfuric acid solution for 84 days. As a result of testing, recycled PET PC, used $CaCO_3$ as filler, makes a problem of appearance and strength if they are exposed for long term at corrosion environment. On the other hand, recycled PET PC, used fly-ash as filler, had less effect on decrease in weight and strength. Recycled PET PC is excellent chemical resistance, resulting in the role of unsaturated polyester resin which consists of polymer chain structure accomplishes bond of aggregates and filler strongly. Also, recycled PET PC, used fly-ash as filler, is stronger resistance of sulfuric acid corrosion than $CaCO_3$, because it is composed of $SiO_2$ and very strong glassy crystal structure. Therefore, recycled PET PC, used fly-ash as filler, is available under corrosion circumstances like sewer pipe or waste disposal plant.

• Journal of the Korean GEO-environmental Society
• /
• v.23 no.9
• /
• pp.33-40
• /
• 2022

Sedimentation and pH neutralization has been investigated as preteatment of acid contaminate water. The settling and neutralizing process derive more effective degradation efficiency as the pre-treatment process before the removal process of adsorption, volatile, biodegradation, or oxidation. Settling velocity, uniformity coefficient, coefficient of curvature, and grain size index can define in the sedimentation process for characteristics of the soil. The stainless steel sieve has been used to separate each particle size of the dry soil by assembling in order of 4, 10, 20, 40, 80, 100, and 200 mesh sizes. The soil from Gamcheon Port in Busan drops upper side of the sieve and shakes back and forth to separate each different size of the particle. The 1L of Imhoff cone and 200 mL of the mass cylinder were used as settling tanks to calculate settling velocity. Stokes' equation was used to figure out the average density of dry soil with a value from settling velocity. In the results, the average particle density and lowest settling velocity were 1.93 g/cm³ and 0.11 cm/s, respectively. These values can detect the range of settling points of sediment to prevent chemical accidents. In pH neutralization, the initial pH of 2, 3, 4, and 5 of nitric acid and sulfuric acid are used as an acid solution; 0.1, 0.01, and 0.001 M of sodium hydroxide and calcium hydroxide are used as a base solution. The main goal of this experiment is to figure out the volume percentage of the acid solution becomes pH 7. The concentration of 0.001 M of base solution exceeds all the conditions, 0.01 M exceeds partially, and 0.1 M does not exceed 5 v/v% except pH 2. Calcium hydroxide present less volume than sodium hydroxide at pH neutralization both sulfuric and nitric acid.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.33 no.2
• /
• pp.412-419
• /
• 2004

To investigate the utilization of calcium lactates (CaL) as coagulants for tofu manufacture, the quality characteristics and shelf-life of tofu made by CaL-P (black snail powder) and CaL-A (black snail ash) were investigated and compared to calcium chloride (CC), magnesium chloride (MC), calcium sulfate (CS ) and standard calcium lactate (CaL-S). And also, total microbe and turbidity of the tofu were determined during storage at 1$0^{\circ}C$. Coagulation ability of CaL-A was the highest, and the ability of CaL-P was higher than that of CaL-S. Yield of CaL-A tofu was similar to those of CS and CC tofu, while the yield of CaL-P tofu was 50% compared to that of CC. L＊ value of CaL-P tofu was lower, but a＊ and b＊ values were higher than those of other tofus. The hardness of tofu showed in the order of CaL-S>CS>CC>CaL-P>MC>CaL-A, while the cohesiveness showed in the order of MC>CaL-S>CC>CS>CaL-P>CaL-A. Calcium contents were 57 mg% in MC tofu, 174 mg% in CS tofu, 116 mg% in CaL-S tofu, 95 mg% in CaL-A tofu and 172 mg% in CaL-P tofu. From the results of microscopic observations, the lower hardness showed the more soft and the smaller particle. The particle of CaL-A tofu was small and uniformity but the size of CaL-P and CC tofu showed coarse. Sensory quality of CaL-P and -A tofu were better than the other tofu evaluated by texture, springiness, flavor and overall taste. The shelf-life estimated by total microbe was 4∼6 days in CC, MC, CS, CaL-S and CaL-A tofu, but 8 days in CaL-P tofu at 1$0^{\circ}C$. From the above results, the CaL-P and -A may believe to use as coagulant for tofu manufacture due to its softened taste and enhanced shelf-life, and higher calcium content which has higher absorbability in human body.