• 상하수도학회지
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• 제18권2호
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• pp.174-180
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• 2004

This study is a fundamental research to test the applicability of abandoned eggshell as seed material for crystallization reaction. Eggshell was calcinated at $850^{\circ}C$ and ground to lesser than 0.42mm. The calcination characteristics of eggshell were examined by X-ray diffraction (XRD). The effect of initial calcium concentration, alkalinity, reaction temperature condition, seed dosage were studied by batch test. For the low concentration sample(P concentration is under 50mg/L), more than 90% of P can be removed. The effect of initial calcium concentration(0~120mg/L) was performed. At the result of the test, more than 50mg/L calcium concentration has high removal efficiency. Alkalinity effect was studied for synthetic solution(100mg/L initial P, 50mg/L calcium, 0.025% seed dosage) with 0~300mg/L bicarbonate alkalinities. For synthetic solution(100mg/L initial P, 50mg/L calcium, 100mg/L bicarbonate alkalinity, 0.025% seed dosage), the phosphorus concentration was examined with $10{\sim}35^{\circ}C$. In addition, calcinated eggshell was injected to swine wastewater to test the applicability to actual wastewater.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2008년도 춘계 학술발표회 제20권1호
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• pp.553-556
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• 2008

전기전도도에 의한 콘크리트의 염소이온 침투저항성 시험방법에 의해 동일 배치의 10개의 콘크리트 공시체의 염소이온 투과시험을 실시하였다. 실험결과 동일한 배합의 시료에 대한 염소이온 투과시험 결과 변동계수가 24% 정도로 나타나고 있어, 이 방법에 의해 얻어진 데이터의 신뢰성은 그다지 높지 않다는 결론을 도출할 수 있었다. 이러한 오차는 구성 재료 자체의 불균질성, 배합상의 오차, 시험방법 상의 오차 등이 모두 복합적으로 작용하여 일어나는 것으로 얻어진 결과를 활용하고자 할 때 이러한 영향으로 인해 도입되는 오차의 범위를 고려하여야 할 것이다. 특히 1개의 공시체에 대한 1회의 시험값을 토대로 연구결과를 내려는 경우 큰 오류를 범할 수 있음을 주지해야 한다.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2007년도 추계 학술논문 발표대회
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• pp.61-64
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• 2007

This study progressed fresh mortar test and hardening mortar test as a characteristic analysis of high strength mortar that is not water but replaced liquid, and the results are summarized as following. As a characteristic of fresh mortar, the flow that is following by the changes of the kind of replaced liquid decreased in order of E, M, A, K, O, L, G, and H, and it is indicated that liquid except H, the flow was better then others. The test show the bending strength of G, L, K, O at and H were more increased then plain as the replaced liquid change on the first day, and on the 28th day, G, L, and K was more increased then plain. The compressive strength of G, K, and O was similar with P(-10) at the first day. On 7th day, the test show G, and L was more increased then P(-10), and other replaced liquid were similar or decreased. On the 28th day, G, K, and A was similar with P(-10) and it is decreased in order of E, L, O, and H.

• 대한환경공학회지
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• 제37권7호
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• pp.387-395
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• 2015

본 논문에서는 Graphical Statistic Analysis (GSA) 방법을 이용하여 유기성 폐자원의 최종생분해도와 다중 분해속도를 평가하였다. GSA에 의한 최종생분해도는 돈분뇨 69%, 젖소 생분뇨 45%, 도축폐기물 66%를 나타냈고 음식물류 폐기물과 음폐수는 각각 79%와 87%이었으며, 1차 슬러지와 폐활성 슬러지는 각각 68%와 39%이었다. 유기성 폐자원의 분해양상을 정확히 표현하기 위하여 사용된 다중분해속도해석(Multi k Analysis) 방법을 이용해 평가한 결과 돈분뇨는 $k_1$ ($0.116day^{-1}$)의 속도로 평균 31일 안에 전체 생분해성 유기물 중 빠르게 분해되는 분율($S_1$)인 89%가 분해되었으며, 느리게 분해되는 $S_2$의 분율은 11%로써 $k_2$ ($0.004day^{-1}$)의 속도로 남은 기간 동안 분해되었다. 젖소 생분뇨는 $k_1$ ($0.074day^{-1}$)의 속도로 평균 29일 안에 분해되었으며 $S_1$의 분율은 91%이었다. 도축폐기물과 1차 슬러지는 $k_1$ ($0.095day^{-1}$)의 같은 속도로 분해되었으며, $S_1$은 각각 89%와 85%를 보였다. 음식물류 폐기물과 음폐수는 15일의 운전기간 동안 $S_1$은 각각 89%와 93%로 기질의 대부분이 분해되었으며 $k_1$은 각각 $0.195^{-1}$과 $0.184^{-1}$로 대단히 빠른 속도로 분해되었다. 폐활성 슬러지는 $k_1$ ($0.054day^{-1}$)의 속도로 28일 동안 분해되었으며 $S_1$은 80%를 보였다. 따라서 Multi k Analysis 방법을 이용해 유기성 폐자원의 분해 속도와 분해 양상을 토대로 최소 HRT를 산정할 수 있으며, 본 대상시료를 활용한 바이오가스화 시설의 최적 설계인자 도출이 가능하다.

• 한국지하수토양환경학회지:지하수토양환경
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• 제29권1호
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• pp.72-83
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• 2024

Most of the slags generated from steel-making industry in Korea are recycled into media-contact aggregates such as fill and cover materials. For their use as media-contact aggregates, the slags must meet not only the waste quality criteria, but also the Daphnia magna acute toxicity test criteria. In this study, Korean Leaching Test ES 06150.e (Korea), Japanese Leaching Test JIS K 0058-1(Japan), Detuch Leaching Test DIN 19529 (Germany), Toxicity Characteristic Leaching Procedure (USA) were conducted for batch leaching test of slags from 6 Korean steel-making companies. In addition, Korean Standard up-flow percolation test (ES 06151.1) mimicking field conditions was conducted to assess the impact of the slag leachate on the surrounding environment indirectly. Heavy metals such as Cr⁶⁺ and Zn²⁺ were detected from both extractant and leachate samples, but all of them did not exceed waste quality criteria of each country. However, Daphnia magna acute toxicity tests using the leachate samples from up-flow percolation test with slag alone and slag/natural soil conditions exceeded ecotoxicity standard (TU=2) due to their high pH (11.3-12.5). After neutralizing the pH of the slag leachate to 6.5~8.5, the Daphnia magna mortality and immobilization were reduced to satisfy ecotoxicity standard. As the reducing pH of slag leachate would be extremely difficult, appropriate recycling management considering the physicochemical characteristics of he slags should be stuided further.

• 한국지반공학회지:지반
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• 제11권3호
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• pp.5-16
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• 1995

본 연구에서는 석탄회를 성토재로 활용시 침출 시간경과에 따른 석탄회 침출수의 성분 및 농도변화 특성을 파악하므로써 주변환경에 미치는 영향을 평가하기 위해 비회 및 혼합회를 대상으 로한 연속식 용출시험과 회분식 용출시 험을 수행하고 시험 결과를 수질기준과 비교, 검토하였다. 시험결과, 대상 석탄회는 일반 폐기물로 분류되었으며,석탄회 침출수의 농도는 시간경과에 따라 급격히 감소하여 일정시간 경과후에는 극히 미미하게 나타났다. 또한 대상석탄회 침출수의 수질은 pH를 제외한 기타 성분들이 모두 음용수 수질기준과 폐수배출 허용기준을 만족하는 것으로 나타났다.

• KSBB Journal
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• 제13권5호
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• pp.469-476
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• 1998

Among 31 water-born microbial strains isolated from various sites in Korea, strain DJ-4 was selected as a test organism for toxicity measurements in that its growth was completely inhibited by the presence of 668.4 mg/L of chloroform and 297.5 mg/L of toluene in the liquid LB medium whereas others did not. It was observed that lag periods and specific growth rates of DJ-4 batch vial cultures were prolonged and decreased, respectively, by phenol, benzene, toluene, ethylbenzene, p-xylene, perchloroethylene, trichloroethylene, and chloroform at the concentrations between 3.6 and 417.8 mg/L. There changes were found to be linear with respect to the concentrations of the toxic compounds. From the first-order regression equations, 50% effective concentrations (EC50${\mu}$ for concentrations of toxic compounds causing 50% decrease of specific growth rates and EC50lag for 50% increase of length of lag periods) were calculated for each compounds. By comparing DJ-4 EC50${\mu}$ values with Daphnia LC50's from a literature for benzene, ethylbenzene, toluene, and trichloroethlyene, it was concluded that microbial specific growth could be a new, fast, and reliable parameter for toxicity tests.

• Journal of Pharmaceutical Investigation
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• 제35권3호
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• pp.207-224
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• 2005

The objective of this study was to explore the principles of SUPAC-SS and its regulatory application in handling postapproval changes to nonsterile semisolid dosage forms. The types of postapproval changes that SUPAC-SS described were modifications in formulation (components and composition), batch size, manufacturing equipment & process, and the site of manufacturing. SUPAC-SS defined the levels of postapproval changes and what chemistry, manufacturing, and control tests should be conducted for each change level. The guidance also specified several occasions the manufacturers should perform in vitro release test (Franz cell diffusion test) and/or in vivo bioequivalence test. Finally, SUPAC-SS classified appropriate filing forms to be used in supporting postapproval changes. It was crystal clear that SUPAC-SS helped maintain the safety and quality of approved semisolid dosage forms when they were subject to certain postapproval changes. The availability of SUPAC-SS made contributions to reducing regulatory burdens of the industry, as well as expediting the postapproval process of regulatory agencies. This study also shed light on the background of relevant pharmaceutical sciences that the SUPAC-SS guidance adopted. Finally, the KFDA and the industry were strongly urged to implant a similar guidance in handling postapproval changes to semisolid dosage forms available in the Korean marketplace.

• Journal of Microbiology and Biotechnology
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• 제23권9호
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• pp.1229-1243
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• 2013

In this paper, an air isolate (NITT6L) has been screened based on hemolytic activity, emulsification activity, drop collapsing test, and oil displacement test, as well as lipase activity. It was found that strain NITT6L was able to reduce the surface tension of the medium from 61.5 to 39.83 mN/m and could form stable emulsions with tested vegetable oils. Morphological, biochemical, 16S rRNA sequencing analyses, and fatty acid methyl ester analysis using gas chromatography confirmed that the air isolate under study was Pseudomonas aeruginosa. Characterization of the biosurfactant using agar double diffusion assay revealed that the biosurfactant was anionic in nature, and CTAB-methylene blue assay and Molisch test revealed its glycolipid nature. The FT-IR spectrum confirmed that the crude biosurfactant was a rhamnolipid. Using unoptimized medium containing sucrose as the carbon source, the isolate was found to produce 0.3 mg/ml of rhamnolipid in batch cultivation (shake flask) at $37^{\circ}C$ and pH 7. Optimization of the medium components was carried out using design of experiments and the yield of rhamnolipid has been enhanced to 4.6 mg/ml in 72 h of fermentation.

• 한국생산제조학회지
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• 제20권5호
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• pp.653-658
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• 2011

In general, the purpose of packaging fasteners is a series of management activities to maintain the condition at the time of production until they get delivered to the end user. An automatic packing system for fasteners is consisted of bucket conveyor, slide feeder, vision inspection system, box-magazine conveyor system and automatic packing machine. Also, the automatic packing machine is consisted of six modules including charging device, clamping/opening device, sealing/cutting device, feeding/air-shower device, supplying/adjusting device and device frame, etc. In this paper, we proposed an automatic packing mechanism of the one station concept for packing work of fastener objects where the continuous batch work is performed in a finite space. The proposed one-station packing mechanism has been optimized through mechanical, dynamical, structural and fluid analyses. And it had been manufactured as the prototype of automatic packing machine. The field test for validation of performance was performed directly at the production line of bolt and screw. In the field test, this packing machine showed an efficiency of about 4.5 times the manual operation. It also showed 30% reduction in the consumption of packing materials compared to the manual operation. This automatic packing machine for fastener objects will be commercialized soon.