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안드로이드 어플리케이션의 화이트박스 테스트를 위한 액티비티기반의 상태도 생성기법
백태산 ( Tae San Baek ),( Ajay Kumar Jha ),이우진 ( Woo Jin Lee ) 한국정보처리학회 2012 한국정보처리학회 학술대회논문집 Vol.19 No.1
본 논문에서는 안드로이드 어플리케이션의 화이트박스 테스트를 위해 안드로이드의 특성인 액 티비티의 라이프사이클을 고려하여 상태도를 생성하는 기법에 대한 연구이다. 상태도를 생성 하기 위해 소스코드에서 역공학을 통해 생성된 호출그래프에 어플리케이션내의 여러 액티비티의 라이프 사이클정보를 추가하여 액티비티 상태도를 생성한다.
Shekhar Aryal,Sailesh Chitrakar,Rajendra Shrestha,Ajay Kumar Jha 한국유체기계학회 2020 International journal of fluid machinery and syste Vol.13 No.4
The hydropower plants under Himalayan basins are mostly characterized by heavy sediment load due to geographical and metamorphic constraints. Run-off-river projects with limited size of the desilting basins allow suspended sediments to get carried into the turbine components causing wear due to sediment erosion. In the case of high head power plants consisting of Francis turbines, a large portion of the hydraulic energy is transformed into kinetic energy within the guide vanes. This causes various instabilities in the flow due to high acceleration and velocity. Some recent studies have shown that due to the combined effect of the secondary flow around the guide vanes and sediment carrying flow, the size of the clearance gap increases, which further aggravates the performance of the turbine. This study takes a reference of one of the power plants in Nepal containing high head Francis turbines. An in-depth analysis of the effect of the sediment in this power plant and sediment erosion in the turbine components has been performed. A CFD analysis of the guide vanes and runner blades corresponding to the same turbine has been conducted and the results are used to analyze the erosion pattern on the actual turbine. The detailed erosion analysis is made possible with a 3D scanner, such that the eroded regions can be captured and classified based on the flow behavior at those regions. Guide vanes and runner blades are found to be the predominant components affected by erosion. It has been seen that most of the erosion affected regions are originated from increasing clearance gaps between guide vane and facing plates caused due to continuous leakage flow within the two sides of the guide vanes.
( Liguo Zhang ),( Qiaoying Ban ),( Jianzheng Li ),( Ajay Kumar Jha ) 한국미생물 · 생명공학회 2016 Journal of microbiology and biotechnology Vol.26 No.8
The effect of pH on propionate degradation in an upflow anaerobic sludge blanket (UASB) reactor containing propionate as a sole carbon source was studied. Under influent propionate of 2,000 mg/l and 35ºC, propionate removal at pH 7.5-6.8 was above 93.6%. Propionate conversion was significantly inhibited with stepwise pH decrease from pH 6.8 to 6.5, 6.0, 5.5, 5.0, 4.5, and then to 4.0. After long-term operation, the propionate removal at pH 6.5-4.5 maintained an efficiency of 88.5%-70.1%, whereas propionate was hardly decomposed at pH 4.0. Microbial composition analysis showed that propionate-oxidizing bacteria from the genera Pelotomaculum and Smithella likely existed in this system. They were significantly reduced at pH ≤5.5. The methanogens in this UASB reactor belonged to four genera: Methanobacterium, Methanospirillum, Methanofollis, and Methanosaeta. Most detectable hydrogenotrophic methanogens were able to grow at low pH conditions (pH 6.0-4.0), but the acetotrophic methanogens were reduced as pH decreased. These results indicated that propionate-oxidizing bacteria and acetotrophic methanogens were more sensitive to low pH (5.5-4.0) than hydrogenotrophic methanogens.
Metabolic Pathways of Hydrogen Production in Fermentative Acidogenic Microflora
( Li Guo Zhang ),( Jian Zheng Li ),( Qiao Ying Ban ),( Jun Guo He ),( Ajay Kumar Jha ) 한국미생물 · 생명공학회 2012 Journal of microbiology and biotechnology Vol.22 No.5
Biohydrogen production from organic wastewater by anaerobically activated sludge fermentation has already been extensively investigated, and it is known that hydrogen can be produced by glucose fermentation through three metabolic pathways, including the oxidative decarboxylation of pyruvic acid to acetyl-CoA, oxidation of NADH to NAD+, and acetogenesis by hydrogen-producing acetogens. However, the exact or dominant pathways of hydrogen production in the anaerobically activated sludge fermentation process have not yet been identified. Thus, a continuous stirred-tank reactor (CSTR) was introduced and a specifically acclimated acidogenic fermentative microflora obtained under certain operation conditions. The hydrogen production activity and potential hydrogen-producing pathways in the acidogenic fermentative microflora were then investigated using batch cultures in Erlenmeyer flasks with a working volume of 500 ml. Based on an initial glucose concentration of 10 g/l, pH 6.0, and a biomass of 1.01 g/l of a mixed liquid volatile suspended solid (MLVSS), 247.7 ml of hydrogen was obtained after a 68 h cultivation period at 35±1oC. Further tests indicated that 69% of the hydrogen was produced from the oxidative decarboxylation of pyruvic acid, whereas the remaining 31% was from the oxidation of NADH to NAD+. There were no hydrogen-producing acetogens or they were unable to work effectively in the anaerobically activated sludge with a hydraulic retention time (HRT) of less than 8 h.
( Qiao Ying Ban ),( Jian Zheng Li ),( Li Guo Zhang ),( Ajay Kumar Jha ),( Yu Peng Zhang ),( Bin Ling Ai ) 한국미생물 · 생명공학회 2013 Journal of microbiology and biotechnology Vol.23 No.3
Propionate is an important intermediate product during the methane fermentation of organic matter, and its degradation is crucial for maintaining the performance of an anaerobic digester. In order to understand the effect of temperature on propionate degradation, an upflow anaerobic sludge blanket (UASB) reactor with synthetic wastewater containing propionate as a sole carbon source was introduced. Under the hydraulic retention time (HRT) of 10 h and influent propionate of 2,000 mg/l condition, propionate removal was above 94% at 30-35ºC, whereas propionate conversion was inhibited when temperature was suddenly decreased stepwise from 30ºC to 25ºC, to 20ºC, and then to 18ºC. After a long-term operation, the propionate removal at 25ºC resumed to the value at 30- 35ºC, whereas that at 20ºC and 18ºC was still lower than the value at 35ºC by 8.1% and 20.7%, respectively. Microbial community composition analysis showed that Syntrophobacter and Pelotomaculum were the major propionate-oxidizing bacteria (POB), and most POB had not changed with temperature decrease in the UASB. However, two POB were enriched at 18ºC, indicating they were low temperature tolerant. Methanosaeta and Methanospirillum were the dominant methanogens in this UASB and remained constant during temperature decrease. Although the POB and methanogenic composition hardly changed with temperature decrease, the specific CODPro removal rate of anaerobic sludge (SCRR) was reduced by 21.4%-46.4% compared with the control (35ºC) in this system.
Binling Ai,Jianzheng Li,Xue Chi,Jia Meng,Ajay Kumar Jha,Chong Liu,En shi 한국생물공학회 2014 Biotechnology and Bioprocess Engineering Vol.19 No.4
This study was conducted to identify theoptimum pH range and the appropriate buffer for butyricacid production from rice straw by fermentation using anundefined mixed culture. A series of experiments conductedat pH levels of 5.0 ~ 7.0 showed that neutral pH improvedrice straw conversion and consequently carboxylic acidproduction. The highest butyric acid production (up to6.7 g/L) was achieved at pH of 6.0 ~ 6.5, while it was only1.7 g/L without pH control or at pH 5.0. Another series ofexperiments conducted at pH 6.0 ~ 6.5 buffered withCaCO3, NaHCO3, NH4HCO3 and their combinationsindicated that different buffers had different effects ontheproduct spectrum, and that CaCO3 combined with NaHCO3was an effective buffer for butyric acid production. Thehighest total volatile fatty acids (about 12.6 g/L) productionand one of the two highest butyric acid concentrations(about 7.6 g/L) were obtained by buffering with CaCO3combined with NaHCO3. PCR-DGGE analysis revealedthat different pH and buffers also influenced the microbialpopulation distribution. Bacteria were suppressed at lowpH , while the bacterial community structures at higher pHvaried slightly. Overall, this study presents an alternativemethod for butyric acid production from lignocellulosicbiomass without supplementary cellulolytic enzyme.
( Jian Zheng Li ),( Li Guo Zhang ),( Qiao Ying Ban ),( Ajay Kumar Jha ),( Yi Ping Xu ) 한국미생물 · 생명공학회 2013 Journal of microbiology and biotechnology Vol.23 No.2
The diversity and distribution of methanogenic archaea in a four-compartment anaerobic baffled reactor (ABR) treating sugar refinery wastewater were investigated by polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE). At an organic loading rate of 5.33 kg COD/m3·day, the ABR could perform steadily with the mean chemical oxygen demand (COD) removal of 94.8% and the specific CH4 yield of 0.21 l/g CODremoved. The CH4 content in the biogas was increased along the compartments, whereas the percentage of H2 was decreased, indicating the distribution characteristics of the methanogens occurred longitudinally down the ABR. A high phylogenetic and ecological diversity of methanogens was found in the ABR, and all the detected methanogens were classified into six groups, including Methanomicrobiales, Methanosarcinales, Methanobacteriales, Crenarchaeota, Arc I, and Unidentified. Among the methanogenic population, the acid-tolerant hydrogenotrophic methanogens including Methanoregula and Methanosphaerula dominated the first two compartments. In the last two compartments, the dominant methanogenic population was Methanosaeta, which was the major acetate oxidizer under methanogenic conditions and could promote the formation of granular sludge. The distribution of the hydrogenotrophic (acid-tolerant) and acetotrophic methanogens in sequence along the compartments allowed the ABR to perform more efficiently and steadily.