• Title/Summary/Keyword: mixing speed

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A Study on the Optimization of Machining Process for Al6061 Using the AWJM (AWJM을 이용한 Al6061 절단조건 최적화에 관한 연구)

  • Lee, Jae-Kwang;Min, Byeong-Hyeon;Ye, Sang-Don;Jea, Wone-Soo
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.5 no.3
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    • pp.65-70
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    • 2006
  • The AWJM(Abrasive Water-jet Machining) technology is one of the cutting technologies, which can cut various materials with 2 or 3 times of the speed of sound. In this study, processing conditions such as jet-pressure, cutting speed, orifice diameter and stand-off distance, are used by following the design of experiments with 3 levels. Al6061 material which is normally applied on the field, is applied. Through the S/N ratio analysis with measured values, the optimization value of processing conditions to minimize the surface roughness and taper value is obtained. The order of significance is as follows; jet pressure, cutting speed, abrasive mixing ratio, orifice diameter and stand-off distance. RSM(Response Surface Method) is applied to find the optimal processing conditions to minimize both the surface roughness and the taper value by using jet pressure, cutting speed and abrasive mixing ratio.

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Effect of Aeration and Agitation Conditions on the Production of Glucoamylase with Aspergillus niger No. PFST-38

  • Oh, Sung-Hoon;O, Pyong-Su;Lee, Cherl-Ho
    • Journal of Microbiology and Biotechnology
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    • v.3 no.4
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    • pp.292-297
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    • 1993
  • Aspergillus niger No. PFST-38 was grown on complex media in 30L agitated fermentors at various aeration rates and stirrer speeds. We could correlate the mixing time as a function of the Reynolds number and the apparent viscosity, as follows. ${\theta}_M=2.95\;\NRe^{-0.52},\;{\theta}_M=1.88\;{\eta_a}^{0.57}$ Also, the effects of the apparent viscosity (${\theta}_a$), the impeller rotational speed (N), the air flow rate ($V_s$), and the mixing time (${\theta}_M$) on the oxygen transfer coefficient, $K_L a$ were determined experimentally, and equated as follows. $K_La=12.04N^{0.88}Vs^{0.71}{n_a}^{-0.83},\;K_La=30.2N^{0.88}Vs^{0.71}{\theta_M}^{-1.45}$ $K_La$ increased as the agitation speed and the air flow rate increased. The rate of $K_La$ increase was dependent more on the rotational speed of impeller than on the air flow rate. The glucoamylase production increased with the increase of the agitation speed upto at 500 rpm and increased with the increase of air flow rate upto at 1.0 vvm. The values calculated from the above equation confirmed that the experimental maximum production of glucoamylase was achieved when the $K_La$ and the apparent viscosity of the broth were $260\;hr^{-1}$ and 1800 cps, respectively.

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Application for Self-Supported Retaining Wall Using Deep Cement Mixing (DCM(심층혼합처리공법)에 의한 자립식 흙막이 적용사례)

  • Jeong, Gyeong-Hwan;Kim, Yong-Wan;Shin, Min-Sik;Han, Kyoung-Tae;Kim, Tae-Hyo
    • Proceedings of the Korean Geotechical Society Conference
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    • 2006.03a
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    • pp.257-267
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    • 2006
  • The earth retaining wall systems for excavation works in a populated urban area or a poor soil deposit can be limited due to various restriction. Thus there are various methods to be applied for them such as the soldier pile method, the diaphragm wall with counterfort and so on. In this study, the self-supported earth retaining wall using the DCM(Deep Cement Mixing) method, including its merits, demerits and some important characteristics occured in the design and the construction stage, was introduced. It might be reference for the other design and construction procedures using the DCM method.

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A Fundamental Study on the Development of AE Water Reducing Agent for Reduction of Bleeding (블리딩 저감용 AE감수제 개발에 관한 기초적 연구)

  • 문학용;김한준;김규용;신동인;한천구
    • Proceedings of the Korea Concrete Institute Conference
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    • 2003.05a
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    • pp.75-78
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    • 2003
  • This study is to investigate the probability to develop the AE Water-reducing agent which can decrease the bleeding by mixing melamine type super-plasticizer(SP) and methyl cellulose(MC) viscosity agent. According to the result, as the mixing ratio of melamine type SP and MC viscosity agent increases, the bleeding is reduced due to a increase of the air content. When the mixing ratio of melamine type SP and MC viscosity agent is 1:2 and 1;3 at the water content of 165kg/$m^3$ and 175kg/$m^3$ respectively, slump and air content are satisfied and bleeding is reduced to some extent, so this is determined as the mixing ratio of AE water reducing agent for reduction of bleeding. It is prove that the developed AE water reducing agent for reduction of bleeding can reduce the amount of bleeding and prohibit the plastic shrinkage crack by slowing down the bleeding speed. Compressive strength of hardened concrete does not make any difference in comparison with plain concrete.

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A Study on Mixing for Injection Molding of Ceramic Turbo-charger Rotor for Automobile Engine. (자동차엔진용 세라믹 터보차져로터의 사출성형을 위한 혼합에 대한 연구)

  • Chang, In-C.;Ko, Jin;Yoon, Jae-R.
    • Journal of the Korean Society for Precision Engineering
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    • v.9 no.4
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    • pp.109-117
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    • 1992
  • Mixing of ceramic-binder system was investigated experimentally and theoretically for application to Ceramic Injection Molding. Polypropylene, stearic acid, and paraffin wax were selected as the binder system, and silicon nitride fine powders were selected as the ceramic material. Single screw ectruder was employed as the mixing equipment. Theoretical analysis was performed to investigate the mixedness of mixture quantitatively. The analysis predicted average residence time average total strain, and average shear stress as a function of screw speed for mixtures of different volume fraction. Qualitative mixedness of mixture and characteristics of mixing were investigated by using SEM and EPMA. In addition, rheological properties of the mixture were investigated by using a capillary rheometer to examine possibility of injection molding.

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A Fundamental Study on the Prediction of Carbonation Progress Using Deep Learning Algorithm Considering Mixing Factors (배합인자를 고려한 딥러닝 알고리즘 기반 탄산화 진행 예측에 관한 기초적 연구)

  • Jung, Do-Hyun;Lee, Han-Seung
    • Proceedings of the Korean Institute of Building Construction Conference
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    • 2019.05a
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    • pp.30-31
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    • 2019
  • Carbonation of the root concrete reduces the durability of the reinforced concrete, and it is important to check the carbonation resistance of the concrete to ensure the durability of the reinforced concrete structure. In this study, a basic study on the prediction of carbonation progress was conducted by considering the mixing conditions of concrete using deep learning algorithm during the theory of artificial neural network theory. The data used in the experiment used values that converted the carbonation velocity coefficient obtained from the mixing conditions of concrete and the accelerated carbonation experiment into the actual environment. The analysis shows that the error rate of the deep learning model according to the Hidden Layer is the best for the model using five layers, and based on the five Hidden layers, we want to verify the predicted performance of the carbonation speed coefficient of the carbonation test specimen in which the exposure experiment took place in the real environment.

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Effects of Mixing Chamber Shape on Cutting Performance in AWJ (AWJ에서 혼합챔버 형상이 절단성능에 미치는 영향)

  • Lee, Hyo-Ryeol;Kwak, Yong-Kil;Kim, Hwa-Young;Ahn, Jung-Hwan;Yeo, Myeong-Heon
    • Journal of the Korean Society of Manufacturing Technology Engineers
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    • v.20 no.5
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    • pp.535-540
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    • 2011
  • It is well known that abrasive waterjet (AWJ) was developed as a kind of high-density energy processing technologies. AWJ is used to obtain cutting quality of various materials such as metal, ceramics, glass and composite materials within a short manufacturing time because of the characteristics of heatless and noncontact processing. However, surface roughness and dimension error like round, burr, taper vary severely according to the processing conditions such as pressure, cutting speed, orifice diameter, stand off distance and abrasive flow rate. In this paper, the effect of the shape of mixing chamber on surface quality is studied. Three types of mixing chamber - round, parabolic, elliptical - are suggested and each performance is compared to that of cylindrical mixing chamber experimentally. From the result, is proved to be the optimal mixing chamber in the aspect of surface quality the parabolic one.

Applicability of Washing Techniques Coupled with High-Pressure Air Jet for Petroleum-contaminated Soils (고압공기분사를 이용한 유류오염토양 세척기법의 적용성 연구)

  • Choi, Sang-Il;Kim, Kang-Hong
    • Journal of Soil and Groundwater Environment
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    • v.11 no.6
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    • pp.61-68
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    • 2006
  • Soil washing techniques coupled with high pressure air jet were applied for diesel-contaminated soils sampled by an underground oil reservoir of which the initial total petroleum hydrocarbon (TPH) ($2,828{\pm}206\;mg/kg$) exceeded 5 times of current standard level (500 mg/kg) regulated by the Soil-Environment Conservation Law. Through several tests, we found that the position of impeller has a critical impact for washing efficiencies. The highest washing efficiency was obtained at an oblique angle (30 degree) for the impeller and optimized mixing speed (300 rpm) that could have high shearing forces. Considered economical and feasible aspects, the optimum mixing time was 10 min. Rate constants of TPH removal derived from the first-order equation were not linearly increased as mixing speed increased, indicating that mechanical mixing has some limits to enhance the washing efficiencies. Application of high-pressure air jet in washing process increased the washing efficiency. This increase might be caused by the fact that the surface of micro-air bubbles strongly attached hydrophobic matters of soil particles. As the pressure of air jet increased, the separation efficiencies of TPH-contaminated soil particles increased. In the combined process of high-pressure air jet and mixing by impeller, the optimum mixing speed and air flow-rate were determined to be 60 rpm and $2\;kg/cm^2$, respectively. Consequently, the washing technique coupled with high-pressure air jet could be considered as a feasible application for remediating petroleum-contaminated soils.

Numerical Study on Characteristics of Turbulence Scheme in Planetary Boundary Layer (난류 모수화 방법에 따른 대기경계층 수치모의 특성에 관한 연구)

  • Jeon, Won-Bae;Lee, Hwa-Woon;Lee, Soon-Hwan
    • Journal of Environmental Science International
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    • v.19 no.2
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    • pp.137-148
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    • 2010
  • This paper investigates the characteristics of turbulence schemes. Turbulence closures are fundamental for modeling the atmospheric diffusion, transport and dispersion in the boundary layer. In particular, in non-homogeneous conditions, a proper description of turbulent transport in planetary boundary layer is fundamental aspect. This study is based on the Regional Atmospheric Modeling System (RAMS) and combines four different turbulence schemes to assess if the different schemes have a impact on simulation results of vertical profiles. Two of these schemes are Isotropc Deformation scheme (I.Def) and Anisotropic deformation scheme (A.Def) that are simple local scheme based on Smagorinsky scheme. The other two are Mellor-Yamada scheme (MY2.5) and Deardorff TKE scheme (D.TKE) that are more complex non-local schemes that include a prognostic equation for turbulence kinetic energy. The simulated potential temperature, wind speed and mixing ratio are compared against radiosonde observations from the study region. MY2.5 shows consistently reasonable vertical profile and closet to observation. D.TKE shows good results under relatively strong synoptic condition especially, mixing ratio simulation. Validation results show that all schemes consistently underestimated wind speed and mixing ratio but, potential temperature was somewhat overestimated.

The Characteristic Analysis and the Manufacture of Explosive ZPP on PMD using the High Speed Mixing Process (고속 혼화공정을 이용한 PMD용 화약 ZPP 제작 및 특성분석)

  • Kim, Sangbaek;Shim, Jungseob;Kim, Junhyung;Ryu, Byungtae
    • Journal of the Korean Society of Propulsion Engineers
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    • v.22 no.3
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    • pp.8-13
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    • 2018
  • Zirconium potassium perchlorate(ZPP) is an igniter composed of potassium perchlorate as an oxidizing agent and zirconium as a fuel with a Viton binder. ZPP has been used to provide an ignition source in the aerospace, propulsion, and automotive industries. This study investigates the manufacturing process and characteristics of ZPP, such performance and shape/calorimetry/pressure characteristics with respect to pyrotechnic mechanical device(PMD). During the production of ZPP, the mixing process was designed to produce uniform particle size and shape by mixing the raw materials at high speed.