• 한국콘크리트학회:학술대회논문집
• /
• 한국콘크리트학회 2002년도 가을 학술발표회 논문집
• /
• pp.211-216
• /
• 2002

Recently, the more the PET bottles are needed, the more waste PET bottles were produced. So, if there was no suitable recycling, that was contaminate our environment and use up the natural resources. This paper deals with the artificial lightweight aggregate(ALA), made of waste PET bottles, and the properties of concrete replaced with ALA. As a result of experiment, it is shown that the specific gravity of PBLA is 1.39, the unit volume weight is 844 kg/$cm^3$, and absorbing rate is 0. In absorbing rate test, the rate is 10 % increased by replacing of 20 % PBLA and the mixture rate for water and cement is 44.6 % and 51.2 %, in case target strength for 240kgf/$cm^2$, and 270kg/$cm^2$, by added PBLA 75 % and 50 % respectively. So, to obtain a certain target strength, appropriate W/C ratio is required the replacement ratio of PBLA.

• 한국식품조리과학회지
• /
• 제13권1호
• /
• pp.30-39
• /
• 1997

대구, 경북지역 초등학교 급식유형별로 도시형, 농촌형 , 도서벽지 형을 대상으로 급식 제공량과 잔식량에 대한 물리적 측정과 아동자가 측정방법을 비교 분석하였고 급식학교 유형별에 따른 급식제공량에 대한 만족도를 조사하였다. 조사대상자의 일반적 특성으로 신장은 도시형이 체중은 농촌형 아동이 다른 유형보다 높게 나타났으며, 남녀간 신장의 차이는 나타나지 않았다. 부모의 교육수준은 도서벽지형의 교육수준이 낮았으며, 부모의 수입정도는 도시형이 높았고, 직업은 부의 경우 도시형, 농촌형에서 사무직이 모의 경우는 주부가 가장 높게 나타났으나 도서벽지 형의 부, 모 직업은 모두 농업으로 나타났다. 급식유형별 물리적 측정에 의한 제공량은 밥류에서 도서벽지형이 가장 많았고 농촌형, 도시형의 순으로 나타났다. 특히 비빔밥은 모두 제공량이 많았으나 농촌형이 335.9g으로 가장 많아서 잔식율에서도 286.7g으로 가장 높게 나타났다. 국종류에서는 농촌형의 제공량이 가장 많았으며 도서벽지형, 도시형 순으로 나타났다. 잔식율은 모두 높았으나 도서벽지형 , 농촌형, 도시형 순으로 나타났다 반찬류에서 알감자조림은 농촌형,도서벽지형,도시형의 순이었으며 잔식율도 높게 나타나 유의차를 보였다(p < .001). 특히 오이양배추 샐러드는 도시형, 농촌형 모두에서 잔식율이 높았다 김치류는 제공량이 농촌형, 도서벽지형, 도시형 순이었고 잔식율로는 농촌형 , 도서벽지형, 도시형의 순으로 나타났으며 배추김치(p < .001)와 깍두기(p < .01)는 유의성을 보여주었다. 급식유형별 아동자가평가에 의한 잔식율은 대부분의 음식에서 농촌형의 잔식율이 높았으며 특히 밥류와 김치류에서 도시형과 도서벽지형보다 유의차(p < .001)가 높게 나타났다. 물리적 측정과 아동자가 측정의 잔식율 비교에서는 닭강정(p < .001)과 국류(p < .001), 김치류(p < .05)를 제외하고는 유의성이 없었다. 급식제공량에 대한 만족도는 거의 모든 음식에서 만족도가 커질수록 잔식율이 낮았다. 밥에서는 모두 만족도가 높았고, 국 종류에서는 낮았으며, 김치류에서는 도서벽지형이 높았는데 거의 모든 음식에서 만족도가 커질수록 잔식율이 낮았다. 이상의 결과로 볼 때 초등학교 급식에서 잔식량을 줄이기 위해서는 여러요인들이 중요하지만 표준조리법을 개발하고 음식항목에 대한 1인분의 양을 설정하기 위하여 시간과 노력이 절감되는 아동자가 측정법을 훈련교육시켜 반복 실행하면 많은 효과가 기대되어진다.

• 한국방사성폐기물학회:학술대회논문집
• /
• 한국방사성폐기물학회 2011년도 춘계학술논문요약집
• /
• pp.93-94
• /
• 2011

• 한국방사성폐기물학회:학술대회논문집
• /
• 한국방사성폐기물학회 2018년도 춘계학술논문요약집
• /
• pp.301-302
• /
• 2018

• 한국물환경학회지
• /
• 제21권1호
• /
• pp.34-39
• /
• 2005

The performance of elutriated acid fermentation with slurry-type piggery waste was investigated, especially to evaluate the effects of temperature and pre-treatment. In the first phase, the acid elutriation reactor with piggery waste after centrifugation operated at both mesophilic and thermophilic conditions to evaluate the effect of temperature. Solubilization yield($gVFAs/gSCOD_{prod.}$) and acidification rate($gVFAs/gSCOD_{prod.}$) in the thermophilic digestion were 0.45 and 0.55, which were higher than those of the mesophilic digestion, 0.25 and 0.45. In addition, the acid elutriation reactor at thermophilic temperature is more effective in removing e-coli. In the second phase, the acid elutriation reactor was fed with piggery waste before centrifugation. With piggery wastes before centrifugation, the solubilization yield and the acidificaton rate were 0.40 and 0.80, respectively, which were higher than the rates using piggery waste after centrifugation at both mesophilic and thermophilic conditions. The higher sludge volume reduction of 80% benefits sludge management. Furthermore, economical advantages can be achieved by removing the pre-treatment process, such as centrifugation. Consequently, the treatment with piggery waste before centrifugation proved to be effective. Also, the optimum temperature condition was estimated at mesophilic or thermophilic conditions, considering solubilization yields and acidification rates, though the system should be heated.

• KSBB Journal
• /
• 제26권5호
• /
• pp.417-421
• /
• 2011

Because beverage waste contains a lot of sugar, it can be used as a valuable resource for energy. But beverage waste is discharged through the water treatment. To prevent the waste of the energy resource, we produced bioethanol by using beverage waste in this study. In order to produce bioethanol, we added distillers stillage and NaOH for fermentation condition (nutrients and pH adjustment). As a results, ethanol concentration was 5.92 vol%. In contrast, ethanol concentration of blank (not added nutrients) was low and fermentation rate was very slow. Because components of the distillers stillage help the yeast growth, fermentation yield and rate was improved. Finally, we operated distillation and dehydration process by using fermented mash and produced fuel bioethanol (more than 99.5 wt%). We think that this results may provide useful information with application of commercial ethanol production using beverage waste.

• 대한설비공학회지:설비저널
• /
• 제15권4호
• /
• pp.362-371
• /
• 1986

In the normal Refrigeration process, the condensation heat of refrigerant s not been used because of its low-temperature waste heat. To recover the condensation waste heat of R-12 refrigerator, a drying and hot water system was designed and experimented. The results obtained were summarized as follows: 1. As the temperature a temosphere was increased, the temperature of discharge gas of compressor was increased. And the temperature was $80-84^{\circ}C$ for air condensing type and was $68-71^{\circ}C$ for water condensing type during summer. 2. The condensation waste heat could be obtained up to $50-55^{\circ}C$ of drying heat-source and Hot water in summer. In this case, recovered rate was about $73\%$. And the more temperature of drying Heat-source and Hot water were increased, the more a recovered rate were decreased. 3. When comparing drying characteristics of Agro-products in dryer of waste heat utilization and Hot air, there was no quality difference in products. But drying time of the former was 3 Hours longer than the latter. 4. The condensation waste heat of compressor could be applied into the drying of marine products, the predrying of agro-products and making hot water. And showed high possibility of the waste heat using in low-temperature storage.

• 환경정책연구
• /
• 제2권2호
• /
• pp.65-79
• /
• 2003

More than 145 million tons of liquid whey is produced world-wide as dairy processing waste per year, and half of it is discarded without proper treatment. Due to its high nutrient value, the environmental impact can be significant. Bioconversion of cheese whey can provide an effective way to reduce the waste and, at the same time, generate economically attractive value-added chemicals. In this study, cheese whey was fermented with P. acidipropionici to produce propionic acid which has a high market value for chemical and pharmaceutical industries. In order to specifically enhance propionic acid production, acetic acid production was suppressed using o-iodosobenzoic acid as an enzyme inhibitor. When grown in the presence of the inhibitor, propionic acid production rate increased by a factor of 2 while acetic acid production rate decreased by a factor of 3. Furthermore, when 0.3 mM of o-iodosobenzoic acid was used, the incipient stage(creeping growth period) was considerably reduced. Therefore, the inhibitor helps the cells begin to grow earlier and speed up the production of propionic acid. Although the production rate of propionic acid effectively increased, the final concentration(or production yield) remained unchanged due to product inhibition. Methods that can reduce product inhibition are being tested combined with o-iodosobenzoic acid to optimize both the production rate and yield. The results are expected to be informative for controlling the other byproducts for other applications.

• 방사성폐기물학회지
• /
• 제19권2호
• /
• pp.271-278
• /
• 2021

In this study, a chlorination technique for recycling Li₂ZrO₃, a reaction product of ZrO₂-assisted rinsing process, was investigated to minimize the generation of secondary radioactive pyroprocessing waste. It was found that the reaction temperature was a key parameter that determined the reaction rate and maximum conversion ratio. In the temperature range of 400-600℃, an increase in the reaction temperature resulted in a profound increase in the reaction rate. Hence, according to the experimental results, a reaction temperature of at least 450℃ was proposed to ensure a Li₂ZrO₃ conversion ratio that exceeded 80% within 8 h of the reaction time. The activation energy was found to be 102 ± 2 kJ·mol^-1·K^-1 between 450 and 500℃. The formation of LiCl and ZrO₂ as reaction products was confirmed by X-ray diffraction analysis. The experimental results obtained at various total flow rates revealed that the overall reaction rate depends on the Cl₂ mass transfer rate in the experimental condition. The results of this study prove that the chlorination technique provides a solution to minimize the amount of radioactive waste generated during the ZrO₂-assisted rinsing process.

• 한국환경과학회지
• /
• 제23권2호
• /
• pp.303-312
• /
• 2014

As for chemical characteristics of cultivated media waste, the total content of nitrogen, phosphoric acid, and potassium was 6.93%; organic matter content was 67.78%; pH and EC were 7.20 and 1.46 ds/m, respectively. Organic acids identified during stabilization included citric acid, oxalic acid, fumaric acid, and acetic acid, which was highest. During the stabilization of cultivated media waste, temperature decreased and pH increased on the 15th day, and the germination index was 88 after the period, indicating that at least 15 days of stabilization is needed when cultivated media waste is used for growth material of crop. As for germination characteristics, when the mixture rate of cultivated media waste was 20% and under, germination of cucumber and oriental melon was favorable without difference compared to the control plots. For lettuce and Chinese cabbage, no statistically significant difference was found when the rate was 10% and under compared to the control plots. As for seedling quality after 20 days of sowing, cucumber, oriental melon, and Chinese cabbage showed favorable growth only when the mixture rate of cultivated media waste was 10% and under; lettuce showed lower growth characteristics regardless of mixture rate when compared to the control plots. Cultivated media waste may be significantly useful for cucumber and oriental melon, but not for Chinese cabbage and lettuce.