• Korean Chemical Engineering Research
• /
• v.53 no.1
• /
• pp.1-5
• /
• 2015

Lactic acid, the most widely occurring hydroxy-carboxylic acid, has traditionally been used as food, cosmetic, pharmaceutical, and chemical industries. Even though it has tremendous potential for large scale production and use in a wide variety of applications, high cost lactic acid materials are primarily problems. Lactic acid can be obtained on either by fermentation or chemical synthesis. In recent years, the fermentation approach has become more successful because of the increasing market demand for naturally produced lactic acid. Generally, lactic acid was produced from pure starch or from glucose. As an alternative, biomass which is the most abundant renewable resources on earth have been considered for conversion to readily utilizable hydrolysate. In this study, we conducted the fermentation method to produce L(+)-lactic acid production from pretreated hydrolysate was investigated by Lactobacillus rhamnosus ATCC 10863. The hydrolysate was obtained from pretreatment process of biomass using Ammonia percolation process (AP) followed by enzymatic hydrolysis. In order to effectively enhance lactic acid conversion and product yield, controlled medium, temperature, glucose concentration was conducted under pure glucose conditions. The optimum conditions of lactic acid production was investigated and compared with those of hydrolysate.

• Journal of the Korea Concrete Institute
• /
• v.28 no.3
• /
• pp.329-340
• /
• 2016

Increase in demotion and repair works on buildings in the construction market generates a large amount of construction waste. Recycling of construction waste is important for saving of resources, preservation of environment and constant advance of the construction industry. Accordingly, the environmental and economic value of recycled aggregate, which is produced after waste concrete is crushed, is increasingly highlighted. It is generally known that compared to concrete made of ordinary aggregate, concrete made of recycled aggregate has low quality, and the low quality is dependent on the amount of the bonding heterogeneous (cement paste and mortar) as well as the amount of the pores within the bonding heterogeneous. Reports on carbonation mechanism shows that the pores of cement-based materials are filled up by the progress of carbonation. Therefore, this study aims at an estimation of the period for optimum carbonation reforming appropriate for the thickness of the bonding heterogeneous of recycled aggregate, based on carbonation mechanism, with a view to improving the product quality by means of filling up the pores of the bonding heterogeneous of recycled aggregate. This study drew the carbonation depth according to the passage of age by calculating the bonding ratio and bonding thickness of the bonding heterogeneous as against the particle size distribution of recycled aggregate as well as by chemical quantitative analysis according to the age of accelerated carbonation of mock-up samples imitating bonding heterogeneous. Based on the correlation between the age of accelerated carbonation and carbonation depth, this study also proposed the estimated period of carbonation reforming of recycled aggregate appropriate for the thickness of the bonding heterogeneous.

• Journal of the Korean Recycled Construction Resources Institute
• /
• v.3 no.1
• /
• pp.15-21
• /
• 2015

Recently, attempts of replacing some of natural aggregate with mix of low quality aggregate are carried out for stable supply of aggregate. However, low quality aggregate such as recycled aggregate produced during the disposal process of construction wastes and by-product aggregate produced by industrial activities has problem of failing to comply to KS Standards. Therefore, we have compared fundamental properties of concrete by using granite crushed aggregate, recycled aggregate, blast furnace and electric arc furnace slag aggregate for effective utilization of lacking aggregate resources. As the result, slump in case of mixed use of aggregate was increased 0~10% compared to single use. Therefore, it is judged to be economically advantageous as it can expect effects in unit quantity or reduction of SP agent. Compressive strength in case of mixed use of aggregate was increased 0~10% compared to single use as it filled internal crevice of concrete with continuous particle size distribution. Accordingly, if we utilize by satisfying standard particle scope through mix of aggregate with different cause of formation in proper ratio, it was possible to confirm utility of mixed aggregate with demonstration of effects of increases of fluidity and compressive strength of concrete.

• Journal of the Korean Applied Science and Technology
• /
• v.29 no.1
• /
• pp.108-115
• /
• 2012

Archaeological waterlogged woods found under the sea, in lakes, or in swamp environments are generally weak and fragile. If waterlogged wood materials were taken out of the water and left without modification, they would collapse and lose their original dimensions completely. Conservation is performed to replace the water with chemical agents and to give dimensional stabilization and durability. EDTA and PEG are the most commonly used in the preservation of wood. pH control-precipitation method is used for recovery of EDTA from waste fluid of archeological waterlogged wood conservation treatment. The black substance is eliminated from wood as Fe-EDTA complex are formed and EDTA is separated and precipitated from Fe-EDTA complexes at pH 2.68 or less. The result of analysis of the precipitated products and the commercial EDTA by FT-IR and FE-SEM showed that precipitated product by pH adjusted was not a type of Fe-EDTA complex, but pure EDTA. Waste fluid produced in PEG treatment shows the black color and has an offensive odor by organic matter extracted from wood. Color of waste fluid is decolored with oxidation reaction by peroxy hydrate. In FT-IR and SEM-EDX of PEG after freeze-drying process, no significant change of functional groups induced from oxidation is observed, and any metal ion does not exist in the solid PEG specimen. The molecular weight of PEG is measured using GPC and viscometry. Properties of PEG before and after preservation treatment, and after oxidation with $H_2O_2$ were not changed. Consequently, the peroxidation with $H_2O_2$ is a reasonable and simple method to decolor the used PEG solution.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.24 no.2
• /
• pp.323-329
• /
• 1995

For the effective utilization of dark meat separated as by-product from skip-jack canning, the dark meat concentrate(DPC) was prepared by removal of extractable materials with ethanol from dried dark meat. Dark meat protein hydrolysate(DPH) was prepared by the hydrolysis of DPC with ${\alpha}-chymotrypsin$. ${\alpha}-Chymotrypsin$ hydrolysed DPC to the extend of 79% during 10hr. The solubility over a pH range 1~12 showed similar trend on the both of DPH and DPC. The highest solubility was 81% on the DPH and was 36% on the DPC at pH 3. The lowest solubility was 65% on the DPH and was 22% on the DPC at pH 7. The content of total free amino acid was higher in the DPC than in the DPH, but the content of total essential free amino acid was higher in the DPH. Especially, the contents of taurine in the DPC and DPH were much higher than those of other amino acids. The result of sensory evaluation on the fish sauce analogue showed good taste, color and odor at the supplemented level of 8g DPH per 100ml of raw solution of fish sauce analogue and didn't show signifcaint difference compared with market fish sauce(p<0.05). On the preparation of surimi gel, 2% substitution of DPH for the supplemented starch was the most appropriate level.

• Natural Product Sciences
• /
• v.11 no.2
• /
• pp.67-74
• /
• 2005

The ethanolic extracts of the leaves and bulbs of Allium victorialis var. platyphyllum (Liliaceae) collected from Daegwallyoung (D) and Ullung Island (U) in Korea were obtained using three different extracting methods. The first extracts, DL-1 DB-1, UL-1 and UB-1, were obtained from leaves (L) and bulbs (B) dried at $90^{\circ}C$, respectively, and the second extracts, DL-2, DB-2, UL-2 and UB-2, were obtained by extracting the leaves and bulbs of fresh plant parts. The third extracts DL-3, DB-3, UL-3 and UB-3 were obtained by incubating leaves and bulbs at $36^{\circ}C$. The six extracts obtained from A. victorialis var. platyphyllum at Daegwanllyoung (cultivated site) were orally administered to examine for a possible antihepatotoxic effect in $CCl_4-induced$ rats. DL-1 exhibited the most pronounced effect. The extracts inhibited serum ALT, AST, SDH, ${\gamma}-GT$, ALP and LDH activities elevated by $CCl_4$ injection and attenuated decreased glutathione S-transferase, glutatione reductase and ${\gamma}-glutamylcysteine$ synthetase activities and a decreased hepatic glutathione. However, the extracts obtained from Ullung Is. (native site) were less active than the extracts from Daegwallyoung, suggesting that A. victorialis var. platyphyllum from the cultivated site is more useful for functional food than of native site. These results also suggest that the antihepatotoxic effect is due to a higher content of hepatic glutathione. Gas chromatography of the twelve extracts showed significantly different sulfides, disulfides or trisulfides contents belonging to volatile sulfur substances (VSS). Nine components were identified on the basis of their mass spectra, namely, dimethyl disulfide, dimethyl trisulfide, diallyl disulfide, dipropyl disulfide, allyl methyl sulfide, allyl methyl trisulfide, 2-vinyl-4H-1,3-dithiin, 3,4-dihydro-3-vinyl-1,2-dithiin, and allithiamine. Extract DL-1 had the highest VSS content. Dried plant materials contained larger amounts of the VSSs than other extracts, and the leaves contained larger amount than the bulbs. These results suggest that heat treatment increases the antiheaptotoxic ability of A. victorialis var. platyphyllum by increasing the proportion of VSSs.

• Journal of the Korean Wood Science and Technology
• /
• v.27 no.2
• /
• pp.78-86
• /
• 1999

The two parts of chestnut peels, outer and inner layers, were collected and investigated for cultivation of various mushrooms, i.e., Pleurotus ostreatus, Lentinus edodes, Hericium ramosum and the others. The inner layer of chestnut peels was contaminated with the mycelia of the blue fungi when collected, consisted of 17~20 % holocellulose, being a good material for growths of the above fungi. The outer layer was considered to be poor materials for fungal growth, because of lower amounts of minerals. Both mushrooms of Pleurotus ostreatus and Hericium ramosum grow well, and were produced fruiting bodies on the solid media containing only inner layers of chestnut peels. The Imhyup No.6 and Imhyup No.7 varieties of Lentinus edodes grow well, but produced few fruiting bodies in the solid media containing only inner layers of chestnut peels. The growth patterns of P. ostreatus and L. edodes were evaluated by production of $CO_2$. and considered to be different according to fungi. The inner layers of chestnut peels as agricultural by-products were considered to be a good material for mushroom cultivation, and outer layers could be used as being added with the other additives. The chestnut peels, being the environmental pollutants in rural areas, was considered to be a good substrate for mushroom cultivation.

• Korean Journal of Food Science and Technology
• /
• v.9 no.3
• /
• pp.183-189
• /
• 1977

Studies were made of the continuous production of Pyridoxal 5'-phosphate (pyridoxal-p) on simultaneously immobilized cell column. Whole-cell of Pseudomonas polycolor having high activity of pyridoxine 5'-phosphate (pyridoxine-p) oxidase and Kloeckera sp. No. 2201 having high activity of catalase were used as the enzyme materials. The enzyme sources were entrapped in a polyacrylamide gel. Enzymatic properties of the simultaneously immobilized cells were investigated, comparing with those of the mixed whole-cells of the microorganisms. The simultaneously immobilized cells had higher enzyme activity than singly immobilized cells of Pseudomonas polycolor. From this result, the simultaneously immobilized pyridoxine-p oxidase-catalase system could be available to exert a protective effect upon the pyridoxine-p oxidase by destroying $H_2O_2$ which is a by-product of pyridoxine-p oxidation. The optimum pH was 9.0 for the immobilized cells and the whole-cells. The optimum temperature was $45^{\circ}C$ for the immobilized cells and $40^{\circ}C$ for the whole-cells. The pyridoxine-p oxidase of the immobilized cells were activated by $Hg^{++}$ and some SH-compounds.

• Resources Recycling
• /
• v.24 no.2
• /
• pp.62-68
• /
• 2015

The high pure tin production was conducted from crude-tin containing waste solder by electro-refining process. The electro-refining process maintained at 0.2V produced tin with purity of 99.98%, whereas a little increase of voltage to 0.3 V resulted tin purity of 99.92%. The high pure tin of 3N in the present process was produced by fixing the voltage at 0.3V. Considering the high pure tin production, the current density was maintained within $100-120A/m^2$ with current efficiency of 94%. Addition of sulfuric acid of 20 ~ 25 g/L to the electrolyte solution was performed in order to keep Pb (lead) concentration below 100 mg/L in the final tin product. The anode slime generated during electro refining process was analyzed by X-ray diffraction (XRD) study to understand the phases of impurities in it. It detected the presence of Cu and Ag in the slime as in the form of $Cu_6Sn_5$, $Ag_3Sn$, whereas Pb occurred as $PbSO_4$ compound.

• Hwankyungkyoyuk
• /
• v.5 no.1
• /
• pp.112-137
• /
• 1993

As the concern with the creation of environmental problems and regulations about them becomes internationally growing, environmental cooperations with countries concerned are emerging as the first item on the political agenda. In case of South Korea, cooperations with countries in the Asian region is needed urgently. In particular, cooperations with North Korea will be an important factor to reunify the Korean peninsula as well as to solve environmental problems in South Korea. Accordingly, it is necessary to seek feasible alternatives and possibilities of coping with international environment in South and North Korea. This study is limited to literature study based on collecting materials and the testimony of former residents in North Korea. The period of study ranges from May to December in 1992. The research findings show the following environmental problems and alternatives : It is recognized in South Korea that the creation of environmental problems is product of economic development. Currently, the Korean government makes an effort to revise environmental administration and law, to encourage environmental education, and to proceed with environmental technology policies by establishing environmental policies together with economic development plans. North Korea ascribes the cause of environmental problems to colonial exploitation by Japan and the U.S. Environmental pollutants in North Korea is relatively less than South Korea, provisions such as environmental conservation movement, environmental education, and environmental administration and law are not well organized in the country. However, North korea will speed up its economic development to solve economic crises. Therefore, it is expected that industrial wastes, corrosion of nature, and water pollution will result in serious environmental problems. The fields expected to cooperate with South and North Korea are in the following : South Korea may adopt the model of the former East and West Germany and proceed to cooperate with North Korea in public sector as well as private sector. The possible programs are such as academic exchange to conserve environment, joint research in the area of the Demilitarized Zone, conservation of ecosystems around Imjin and Pukhan Rivers, South Korea's support of advanced environmental technology and industrial and financial aid to North Korea. Conflicts between countries concerned in the North East Asian region will be caused by the responsibilities of pollutions because of the seashore development of the Yellow Sea by South Korea and increasing seashore industrial complexes around the Yellow Sea in China, Therefore, it is desirable that the two countries will participate in organizations related to environment. Joint projects between South and North Korea will be as follows : 1. Construction of long-range monitoring system : 2. Investigation of the state of pollutions around the Yellow Sea and alternatives : 3. Construction of joint monitoring system to regulate the movement of pollutants : 4. Cooperation of environmental technology and exchange of information ; and 5. Support of Cooperation of environment in private sector. Efforts to cooperate with North korea is expected to overcome differences between the two countries as well as to encourage unification of the korean peninsula, which will lead to reducing the cost of environmental recovery. These efforts will also contribute to the maintenance for peace and stability on the korean peninsula as well as in the North East Asian region.