• Journal of the Korea Concrete Institute
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• v.14 no.3
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• pp.420-429
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• 2002

The amount of $CO_2$-silicate bonded waste foundry sand(WFS) occurred in Korea is over 800,000 ton per year. WFS, as a by-product, is generated through manufacturing process of foundry may affect our environmental contamination, The reason is that WFS has been buried itself not less than 90％ out of total WFS. So, it can give damage on the ground of contamination in soil and underwater. Therefore, it is necessary to establish the method recycling WFS because of being intensified waste management law. In this study, we performed the research with respect to harmful component analysis, the qualities of WFS mortar and concrete mixed with WFS. As the results the specific gravity of WFS is the same as that of natural aggregate while unit weight and percentage of solids of WFS are smaller than those of it. But it is found that WFS can be used by substituting WFS for natural aggregate after control of poor grade of WFS. The flowability of mortar and concrete with WFS is inferior to those of natural aggregate, and the setting time of concrete with WFS is faster than that with only natural aggregate, On the contrary, the bleeding of concrete with WFS is shown good result, and compressive and tensile strength of concrete substituted WFS for 30％ are higher than those with only natural aggregate regardless of elapsed time.

• Journal of the Korean Chemical Society
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• v.48 no.6
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• pp.590-598
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• 2004

The preconcentration and determination of trace Cu(II) and Pb(II) on calcium alginate beads in aqueous solution were studied. A calcium alginate beads were prepared by adding an alginic acid to sample solution contained Ca(II). Some following conditions were optimized: the pH of sample solution, amount of alginic acid, and stirring time for effective adsorption; the type and concentration of acid, and sonication time in an ultrasonic vibrator for the perfect de-sorption. A sample solution was prepared with Cu(II) and Pb(II) in DI water. And Ca(II) and ethanol was added into the sample solution. The pH of the final sample solution was controlled with buffer solution. The alginic acid were dispersed in the sample solution by a magnetic stirrer. This mixture was stored in room temperature for 30 min to form a calcium alginate. After the beads were filtered and washed on a membrane filter, the analytes were redissolved from the beads by an ultrasonic vibration of 10 minutes in 1.0M $HNO_3$ solution. The effect of diverse ions on the adsorption of analytes were studied. This procedure was applied for the analysis of two real samples. The recoveries in spiked samples were $90.4{\sim}104.3%$ for analytes.

• Journal of dental hygiene science
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• v.2 no.2
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• pp.105-113
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• 2002

This study was aimed to investigate the practice on the infection control and dental waste disposal in dental clinic. The data used in this study had been collected in 100 dental clinics located in Seoul city from August to October, 2001. It was shown that examination instruments, oral surgery instruments, and periodontal instruments were almost sterilization in dental clinic. It was high in the recognition of individual protection but it was low in the degree of practice. Therefore, the practice in infection control is very important to dental team for safety of patients and operators.

• Journal of Ginseng Research
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• v.26 no.3
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• pp.145-150
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• 2002

The changes in sensory characteristics, physical and chemical properties of raw ginseng (4-year-root, 50 g/root) were investigated when they were packaged individually in a soft film bag (ONY/LDPE/L-LDPE ; 200$\times$300 ㎜, 90 ㎛) and stored at 25$\^{C}$ for twenty days. Seventy-five percentages of sixty raw ginseng samples were adulterated and the most phenomenon of adulterating the raw ginseng was softening. Softened ginsengs were softer and stickier and they had stronger pungent and sour odors, stronger sour and sweet tastes than normal ginseng but had weaker ginseng and fresh odors. In addition, softened ginsengs exhibited lower hardness and pH, lower contents of diol-type ginsenosides, lower ratios of unsaturated fatty acids to saturated fatty acids and higher contents of water-soluble pectins than normal ginseng while contents of moisture, crude protein, ether-soluble materials and crude ash of the softened ginsengs were similar to those of normal ginseng.

• Applied Biological Chemistry
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• v.39 no.5
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• pp.384-388
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• 1996

This research was conducted to investigate the effective methods for browning inhibition on yam (Dioscorea aimadeimo) during dehydration by physical and chemical pretreatments. Moisture, crude protein, crude fiber and N-free extract contents of yam were 81.17%, 1.43%, 0.29% and 15.81%, respectively. Yams were sliced to 0.5 cm thickness and placed to single and poly layer in plastic tray, and then changes of their weights were measured during air dehydration at $50^{\circ}C,\;65^{\circ}C,\;and\;80^{\circ}C$. The dehydration time reaching to optimum moisture level for the pulverization of the yam slices were 10, 6, 3 hours(single layered) and 12, 7, 5 hours(multi layered) at the respective temperature. To inhibit browning at $80^{\circ}C$ air dehydration, water and steam blanching, microwave treatment effects were investigated on yam slices for 30 sec. and 60 sec. Steam blanching for 30 sec. was comparatively effective to inhibit browning of yam slices. Yam slices were immersed in single and combined browning inhibitor solutions and evaluated for browing degree during dehydration by the values of Hunter L, a, b and ${\Delta}E$. The most effective pretreatment to inhibit browning of yam slices was immersion In the solution containing 500 ppm of citric acid and 1000 ppm of cysteine for 1 min.

• Journal of Food Hygiene and Safety
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• v.17 no.2
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• pp.79-86
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• 2002

Aflatoxin is a secondary fungal metabolite and is a public health hazard because it is a human carcinogenic and has many deleterious effects in men and animals. Rice is one of the better substrates far the fungus which can produce aflatoxins. This study was performed to investigate aflatoxin reduction during the cooking and processing of rice. Aflatoxin was produced by Aspergillus parasiticus ATCC 15517 on well-milled rice (Japonica type) at the level of 13.2 ppb. Cooked rice, rice cakes (baek-sol-gi, plain steamed rice bread), fermented rice (sikhye, sweet rice beverage), and popped rice were prepared from the aflatoxin-contaminated rice. Aflatoxin content in the samples was determined by high performance liquid chromatography. The total aflatoxin level was decreased to 46.9% in the cooked rice, 85.6% in the rice cakes, 11.4% in the fermented rice, and 7.6% in the popped rice, respectively (p.0.05). This reduction brought the level of aflatoxins down to below the Standard and Specification of korea (10 ppb), except for the rice cakes. These results indicate that washing, steaming, fermentation, and popping of rice was helpful in reducing the aflatoxin level in the rice and the most helpful factors were high temperature & high pressure. More research is needed to understand why the preparation of rice cakes did not reduce the level of aflatoxin as much as the other cooking methods.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.9
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• pp.196-205
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• 2016

The exhaust gas discharged by cars not only threatens the health of the human body, but also contributes to global warming, due to the resulting increase in the concentrations of ozone, fine dust and carbon dioxide. Therefore, the government has steadily implemented careful inspection systems for exhaust emissions, in order to efficiently regulate the exhaust gas of cars. Studies on reducing the exhaust emissions of automobiles have been conducted in various fields, including ones designed to reduce the generation of HC, NOx, and $CO_2$ in the exhaust emission of vehicles. However, there have been insufficient studies on the reduction of the exhaust emission for old diesel vehicles. To develop careful inspection systems for the exhaust emissions of old diesel vehicles, studies on the reduction of the exhaust emissions and improvement of power are necessary by cleaning the carbon sediment in both the intake manifold and injector. Therefore, in this study, we analyzed and compared the amounts of gas emitted when simultaneously cleaning or not cleaning the intake manifold and injector of diesel automobiles with mileages over 80,000 km and operating periods over 5 years. The experimental results showed that in the case where the intake manifold and injector were simultaneously cleaned, there was a decline of 75.2% in the gas emission compared to the cases where only the manifold or injector is cleaned. Also, it was found that simultaneously cleansing the intake manifold and injector enabled the exhaust standard to be satisfied for less than 30% within 8.5 sec.

• Proceedings of the Korea Water Resources Association Conference
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• 2016.05a
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• pp.566-566
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• 2016

정부의 4대강 물 관리 종합대책에 따르면, 수계 전체 오염원중 비점오염원이 차지하는 오염부하가 22~37%에 달하는 것으로 추정되고 있다. 하지만 이러한 중요성에도 불구하고 농업지역 비점오염물질 저감을 위한 대책은 논과 밭과 같이 농경지에 관한 것이 대부분이었으며, 축산은 관리 기준의 가장 기초라고 할 수 있는 지목분류기준에 조차 별도의 기준이 없는 실정이다. 가축분뇨공공처리시설과 가축분뇨자원화시설은 가축분뇨를 처리하여야 하는 점오염원이지만, 차량 운반시 발생되는 일부 분뇨와 처리장 세척 시 발생되는 일부 오염물질들이 비점오염원으로 작용하고 있으며 이에 대한 관리가 미흡한 실정이다. 따라서 본 연구에서는 가축분뇨공공처리시설과 가축분뇨자원화시설에서 강우시 발생되는 유출특성을 분석하였으며, 이를 통해 가축분뇨처리시설의 비점오염 관리 처리시설 설치 시에 중요한 기초자료로 활용하고자 한다. 본 연구에서는 경상북도 영천시, 경기도 용인시, 전라북도 정읍시, 강원도 횡성군 등 축산밀집 지역을 대상으로 연 5회 강우시 모니터링을 실시하였으며, 모니터링자료를 바탕으로 유량가중평균농도(Event Mean Concentration, EMC)를 산정하였다. 영천시 가축분뇨자원화시설의EMC 산정결과 평균 BOD 5.1 mg/L, TN 6.90 mg/L, TP 0.91 mg/L로 산정되었으며, 용인시 개별처리농가의 경우 BOD 6.8 mg/L, TN 3.74 mg/L, TP 1.04 mg/L로, 횡성군 가축분뇨공공처리장의 경우 BOD 4.5 mg/L, TN 3.56 mg/L, TP 1.60 mg/L로, 정읍시 가축분뇨공공자원화시설의 경우 BOD 4.3 mg/L, TN 6.82 mg/L, TP 0.48 mg/L로 산정되었다. BOD, TN은 영천시 가축분뇨자원화시설에서 가장 높게 나타났고, TP의 경우 횡성군 축산폐수공공처리장의 경우 높게 나타났다. 유출특성을 분석한 결과 가축분뇨자원화시설의 경우 대부분 콘크리트 기반으로 조성된 토지위에 조성되어 강우시 유량은 급격하게 상승하며, 강우가 종료되면 바로 감소하는 불투수층 지역의 특성을 나타났다. 본 연구에서 분석된 유츨특성과 EMC는 비점오염 처리시설이나 가축분뇨공공처리시설 설치시 기초데이터로 활용이 가능할 것으로 판단되며, 향후 가축분뇨처리시설의 지속적인 모니터링과 모니터링지점 확대로 자원화시설 강우유출수의 DataBase화를 통한 지속적인 연구 및 관리가 되어야 할 것으로 판단된다.

• Journal of Life Science
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• v.29 no.2
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• pp.198-201
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• 2019

Recently, it has been reported that Bacillus mojavensis possesses antifungal properties and plant growth-promoting activities, which are similar to the characteristics of siderophore. In this study, the siderophore produced by B. mojavensis was assessed using a solid phase extraction (SPE) cartridge and liquid chromatography quadrupole time-of-flight tandem mass spectrometry (Q-TOF MS/MS). After B. mojavensis was incubated in phenol medium for 16 hr and lyophilized, the sample was dissolved in water and loaded to an SPE cartridge to remove interferences. The cartridge was washed with 5% methanol in water and eluted with 2% formic acid in methanol sequentially. The eluted solution was evaporated under a stream of nitrogen gas and reconstituted in methanol. The reconstituted sample was filtered, and $1{\mu}l$ of the sample was assessed using Q-TOF MS/MS. The mass spectrometer was operated using the positive electrospray ionization mode. Based on the mass spectrum and tandem mass spectrum, the siderophore produced by B. mojavensis was bacillibactin, one of the catechol types of siderophore with a molecular weight of 882.2556. This siderophore analysis could provide a justification for the study of B. mojavensis as a functional food and for pharmaceutical applications.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.5
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• pp.81-86
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• 2019

Metal oxide/graphene composites have been known as promising functional materials for advanced applications such as high sensitivity gas sensor, and high capacitive secondary battery. In this study, tin dioxide ($SnO_2$) nanostructures were grown on chemically synthesized graphene nanosheets using a two-zone horizontal furnace system. The large area graphene nanosheets were synthesized on Cu foil by thermal chemical vapor deposition system with the methane and hydrogen gas. Chemically synthesized graphene nanosheets were transferred on cleaned $SiO_2$(300 nm)/Si substrate using the PMMA. The $SnO_2$ nanostuctures were grown on graphene nanosheets at $424^{\circ}C$ under 3.1 Torr for 3 hours. Raman spectroscopy was used to estimate the quality of as-synthesized graphene nanosheets and to confirm the phase of as-grown $SnO_2$ nanostructures. The surface morphology of as-grown $SnO_2$ nanostructures on graphene nanosheets was characterized by field-emission scanning electron microscopy (FE-SEM). As the results, the synthesized graphene nanosheets are bi-layers graphene nanosheets, and as-grown tin oxide nanostructures exhibit tin dioxide phase. The morphology of $SnO_2$ nanostructures on graphene nanosheets exhibits complex nanostructures, whereas the surface morphology of $SnO_2$ nanostructures on $SiO_2$(300 nm)/Si substrate exhibits simply nano-dots. The complex nanostructures of $SnO_2$ on graphene nanosheets are attributed to functional groups on graphene surface.