Optimization of Electric Field-assisted Ultrasonication for Disintegration of Waste Activated Sludge

( Kyung-won Jung ),( Tae-un Jeong ),( Min-jung Cha ),( Kyu-hong Ahn ) 한국폐기물자원순환학회(구 한국폐기물학회) 2014 한국폐기물자원순환학회 심포지움 Vol.2014 No.1

In the present study, an electric field is applied in order to disintegrate waste activated sludge (WAS). As a preliminary step, feasibility tests are investigated using different applied voltages of 10 to 100 V for 60 min. As the applied voltage increases, the disintegration degrees (DD) are gradually enhanced, thereby the soluble N, P, and carbohydrate concentrations increase simultaneously due to the protein decomposition. Subsequently, an optimization process is conducted using response surface methodology with a Box-Behnken design (BBD). The total solid concentration, applied voltage, and reaction time are selected as independent variables, while the DD is selected as the response variable. The overall results demonstrate that the BBD with an experimental design can be useed effectively in the optimization of the electric field treatment of WAS. In the confirmation test, a DD of 10.26±0.14% is recorded, which corresponds to 99.1% of the predicted response value under the statistically optimized conditions. Finally, the statistic optimization of the combined treatment (electric field + ultrasonication) showed that even though this is limited to highly disintegrated WAS when being applied individually, a high DD of 47.28±0.20% was recorded where the TS concentration was 6,780 mg/l, the strength of ultrasonication was 8.0 W, the applied voltage was 68.4 V, and the reaction time was 44 min. E-SEM images clearly revealed that the application of the electric field is a significant alternative method for the combined treatment of WAS, and this is first attempt to increase disintegration using electric field for combined treatment with ultrasonication.

애엽, 지각, 아교주 및 목향의 투여가 임신중 생쥐의 생식능력에 미치는 효과

정형민,차수경,임정묵,신태은,박찬,장준복,이경섭,송병기 경희대학교 2000 慶熙醫學 Vol.16 No.2

디젤엔진排出에서 나노PM 粒子計測用 凝縮核개수기(CPC) 特性에 關한 比較解析

鄭珉元,崔源鶴,柳鍾植,李海喆,車京玉 明知大學校 産業技術硏究所 2008 産業技術硏究所論文集 Vol.27 No.-

Recently, the nano-PM 's number concentration emitted by diesel internal combustion engine has focused on attention because this particulate matters are suspected being hazardous of human health. In this study, the particulate matters (PM) emissions of these vehicles were investigated by number concentration. A condensation particle counter (CPC) system was applied to measure the particle number and size concentration of diesel exhaust particles at the end of dilution tunnel along the NEDC(ECE15+EUDC) vehicle test mode using TSI 3010D and HCT 4312 CPC. As the research result, the characteristic of CPC comparison diesel nano-particle number and size distribution was investigated in this study.

교정용 열가소성 재료의 두께와 변형량이 재료의 물리적 특성에 미치는 영향

민샘,황충주,유형석,이상배,차정열 대한치과교정학회 2010 대한치과교정학회지 Vol.40 No.1

Objective: The purposes of this study were to evaluate the force and stress depending on the type, deflection and thickness of the materials and to evaluate the mechanical properties of thermoplastic materials after repeated loading. Methods: Four types of thermoplastic products were tested. Force until the deflections of 2.0 mm and the stress when the materials were restoring to its resting position were evaluated. The mechanical properties of thermoplastic materials evaluated after 5 repeated loading cycles. Results: The interaction was observed between the thickness and the deflection (p < 0.05) from the regression equation. Thickness and amount of deflection rather than products and materials showed the largest effect on force and stress. In all products, at least 159 gf of force was required for more than 1.0 mm deflection or when materials with 1.0 mm thickness were deflected. The stress recorded was more than 19 gf/mm². During repeated loading, each group showed significant difference on the force and the stress (p < 0.01), 10 - 17% reduction of force and 4 - 7% reduction of stress in average. Conclusions: Proper thickness of thermoplastic materials and deflection level of tooth movement should be decided for the physiologic tooth movement. Force decay after repeated loading should be considered for the efficient tooth movement. 다양한 열가소성 교정 재료를 이용한 성공적인 임상 결과가 보고되었지만, 재료의 물리적 성질에 관한 연구는 많지 않다. 본 연구는 열가소성 재료의 종류, 두께, 변형량과 반복변형에 따른 변형 시 필요한 하중과, 변형되었던 재료가 원래의 상태(resting position)로 돌아갈 때 재료의 복원력을 평가하였다. 실험적인 모델의 조건에서 투명교정장치의 재료로 쓰이는 4가지 종류의 열가소성 재료(0.5 mm, 0.75 mm, 1.0 mm 두께)를 최종 변형량이 2.0 mm가 될 때까지의 하중(gf)을 측정하였다. 변형 후 탄성력에 의해 원점으로 회복될 때, 재료의 복원력(gf/mm²)을 측정하였다. 동일한 방법으로 5회 반복변형 동안의 하중과 복원력의 변화를 측정하였다. 그 결과, 열가소성 재료의 두께와 변형량에 대해 상호 교호작용이 관찰되었으며 (p < 0.05), 열가소성 재료의 두께 및 변형량이 하중과 복원력에 가장 큰 영향력을 나타내었고 재료 간 혹은 제품 간의 하중과 복원력에는 유의한 차이가 없었다. 두께가 1.0 mm이거나 또는 1.0 mm 이상 변형인 경우 최소 159 gf의 하중이 필요하였고, 최소 16 gf/mm2의 복원력이 발생하였다. 각 실험군에 대한 반복하중 시 하중과 복원력에서 유의한 차이가 관찰되었고 (p < 0.01), 평균 10 - 17%의 하중 감소와 4 - 7%의 복원력 감소가 관찰되었다. 이상의 결과, 하중과 복원력에 가장 영향을 많이 주는 요소는 재료의 두께와 치아의 이동량 이었다. 제품에 상관없이 두께가 1.0 mm 이상인 재료를 사용하거나 치아를 1.0 mm 이상 이동 시에는 과도한 힘이 발생하였다. 따라서 투명교정장치를 이용하여 생리적으로 치아를 이동시키기 위해서는 초기 치아배열을 위해 사용하는 열가소성 재료의 두께와 셋업 시 치아 이동량을 고려하여 과도한 힘이 가해지지 않도록 해야 한다. 또한 반복하중 후에 열가소성 재료의 피로도에 의한 힘의 상쇄를 고려하여 임상에 적용해야 한다.

갈륨-비소 반도체 소자의 단전자 수송에 관한 몬테칼로 시늉내기

정원호,차민철 한양대학교 이학기술연구소 2001 이학기술연구지 Vol.3 No.-

본 논문에서는 two valley model(Г-L) single-electron Monte Carlo(SMC) method를 사용하여 GaAs의 격자 온도 변화, 전기장, 불순물 농도에 따른 전자 전송 특성(속도, 에너지, velly 점유율)을 조사함으로써 반도체(GaAs)내부의 물리적인 정보를 얻었다. 산란 과정으로는 polar optical phonon(POP), non-POP, acoustic phonon, ionized impurity 산란이 고려되었고, Monte Carlo method의 유일한 단점인 긴 계산 시간을 줄이기 위하여 fast self scatterning method를 적용하였다. In this paper, the electron transport characteristics of velocity, energy and valley occupancy have been investigated as a function of various parameters, such as lattice temperatures, electric fields, or impurity concentrations by using 'two valley model(Г - L) in GaAs single-electron Monte Carlo(SMC) method'. We have considered scattering due to polar optical phonons(POP), non-POP, acoustic phonons and ionized impurities. In order to reduce CPU time, which is a crucial point in the Monte Carlo method, a fast self-scattering method has been applied.

Pseudomonas stain HK-6에 의한 폭발물 RDX(Hexahydro-1,3,5-Trinitro-1,3,5-Triazine)의 생분해

정관구,차민석,오계헌 순천향대학교 기초과학연구소 2000 순천향자연과학연구 논문집 Vol.6 No.2

The feasibility using an isolate derived from the enriched microbial consortium for explosive degradation was explored. The present study reports on the isolate which was developed to grow aerobically with RDX (hesahydro-1,3,5-trinitro-1,3,5-triazine) as the sole sources of carbon and nitrogen. Complete depletion of RDX a the initial concentration of 15 mg per liter was achieved within 24 days of incubation in bench-scale bioreactors. Addition of supplemental carbons (e.g., succinate, glucose, fructose) stimulated the degradation of RDX. The isolate also could degrade structurally related explosive 2,4,6-trinitrotoluene. Degradation of RDX was verified by HPLC analysis of the residual RDX concentration in the test culture. Microscopic examination of this degrader, HK-6 revealed a Gram-negative and coccobacillus shaped cell. Strain HK-6 was characterized by using the Biolog system and an analysis of the total cellular fatty acids. The strain indicated that the bacterium could be identified and designated as pseudomonas putida HK-6

디젤 乘用車輛에서 DPF 條件에 따른 極微細粒子의 排出 特性에 關한 硏究

鄭珉元,崔源鶴,柳鍾植,李海喆,車京玉 明知大學校 産業技術硏究所 2008 産業技術硏究所論文集 Vol.27 No.-

Recent1y, the nano-PM(Particulate Matters) number concentration emitted by diesel internal combustion engine has focused on attention because this nano-PM is suspected being hazardous of human health. In this study, the PM of the diesel passenger vehicles were investigated by number concentration. A condensation particle counter (CPC) system was used to measure the particle number concentration and size of diesel exhaust particles at the end of dilution tunnel during the NEDC(ECE15+EUDC) vehicle test mode using light-duty diesel passenger vehicles with DPFs. As a research result, the characteristic of DPF performance about diesel nano-particle number concentration and size distribution was investigated in this study.

자외선 조사에 의한 피부조직 단백질의 산화에 관한 연구

차승훈,정영도,이승철,안봉환,김영표,이민화 한국노화학회 1991 한국노화학회지 Vol.1 No.1

Gitelman씨 증후군 1예

차영학,송명준,신요식,김성민,김영욱,김윤권,김소연,김영중,조민구,이권전 全南大醫大 2001 전남의대학술지 Vol.37 No.3

교정용 미니스크류의 디자인에 따른 식립 및 제거 토오크

차정열,윤태민,황충주 대한치과교정학회 2008 대한치과교정학회지 Vol.38 No.1

교정용 미니스크류의 원추 형태가 식립 후 시기별 안정성에 미치는 영향을 알아보기 위해, 시기별 제거 토오크 및 동요도와 조직시편분석을 시행하였다. 성견 6마리의 하악 협측골에 원통형과 원추형 교정용 미니스크류(Biomaterials Korea, Seoul, Korea) 48개를 식립하고, 식립 시 식립 토오크와 동요도를 측정하고 3주, 12주 동안 교정력을 부여한 후, 제거 시 제거 토오크와 동요도를 측정하였다. 식립 토오크는 원통형 미니스크류에서 13.6 Ncm, 원추형 미니스크류에서 22.3 Ncm로 원추형 미니스크류에서 높은 식립 토오크가 측정되었다 (P < 0.001). 식립 3주째 제거 토오크는 원통형 미니스크류에서 5.7 Ncm, 원추형 미니스크류에서 9.1 Ncm로 유의한 차이가 관찰되었다(P < 0.05). 식립 12주째 원추형 미니스크류의 제거 토오크는 3.6 Ncm로 유의하게 감소하여(P < 0.05) 원통형 미니스크류의 4.2 Ncm와 유의한 차이를 보이지 않았다. 이상의 결과로 미니스크류의 원추 구조는 식립 토오크를 유의하게 증가시켜 식립 후 3주간 안정성에 도움이 되었으나, 12주 후 안정성에 있어서는 원통형 미니스크류와 유사하였음을 시사한다. Objective: This study was designed to analyze the primary and secondary stability characteristics of orthodontic mini-screws of tapered design when compared with the cylinder mini-screw. Methods: A total of 48 mini-screws were placed into the buccal alveolar bone of the mandible in 6 male beagle dogs. Comparison was made between tapered and cylinder type mini-screws (Biomaterials Korea, Seoul, Korea). Maximum insertion torque (MIT) was measured using a torque sensor (Mark-10, MGT50, USA) during installation, and maximum removal torque (MRT) was recorded after 3 and 12 weeks of loading. Results: Taper mini-screws showed a higher MIT value of 22.3 Ncm compared with cylinder mini-screw showing 13.6 Ncm (P < 0.001). The MRT of the taper mini-screw showed a significantly higher value of 9.1 Ncm than those of cylinder mini-screw of 5.7 Ncm at 3-weeks after installation (P < 0.05). However, there was no difference in the MRT value between the taper and cylinder mini-screws at 12 weeks of loading. Conclusions: These results showed that the high insertion torque of the taper mini-screw design increases initial stability until 3 weeks of loading, but does not have any effect on the secondary stability at 12 weeks of loading.