• Title/Summary/Keyword: mixture experimental design

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Air Jet Effect on Performance Improvement of Non-Contact Type Seals for Oil Mist Lubrication Systems (공기분사가 오일미스트 윤활 시스템용 비접촉 시일의 성능 향상에 미치는 영향)

  • Na, Byeong-Cheol;Jeon, Gyeong-Jin;Han, Dong-Cheol
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.24 no.9 s.180
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    • pp.2159-2166
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    • 2000
  • Recently, high performance machining center requires special type of sealing mechanism that prevent a leakage of oil jet or oil mist lubrication system. Sealing of oil-air mixture plays important r oles to have an enhanced lubrication for performance machining center. Current work emphasizes on investigations of the air jet effect on the protective collar type labyrinth seal. To improve sealing capabilities of conventional labyrinth seals, air jet is injected against the leakage flow. In this study, an adapted model is introduced to improve sealing capability of conventional non-contact type seals. It has a combined geometry of a protective collar type and an air jet type. Both of a numerical analysis by CFD (Computational Fluid Dynamics) and experimental measurements are carried out to verify sealing improvement. The sealing effects of the leakage clearance and the air jet magnitude aic studied in various parameters. Gas or liquid has been used as a working fluid for most of nori-contact types seals including the labyrinth seal. However, it is more reasonable to regard two-phase flows because oil mist or oil jet are used for high performance spindle's lubrication. In this study, working fluid is regarded as two phases that are mixed flow of oil and air phase. Both of turbulence and compressible flow model are also introduced in a CFD analysis to represent an isentropic process. Estimation of non-leaking property is determined by amount of pressure drop in the leakage path. Results of pressure drop in the experiment match reasonably to those of the simulation by introducing a flow coefficient. Effect of the sealing improvement is explained as decreasing of leakage clearance by air jetting. Thus, sealing effect is improved by amount of air jetting even though clearance becomes larger

Design, Analysis and Experiment of Potato Gun with a Spherical Projectile (구형 탄환을 이용한 감자총의 설계, 해석 및 시험)

  • Kang, Hong-Jae;Kim, Ji-Hwan;Kim, Young-Sik;Son, So-Eun;Choi, Han-Ul;Choi, Jeong-Yeol
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.41 no.10
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    • pp.796-804
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    • 2013
  • The "Potato Gun," a simple heat engine, is fabricated, tested and analyzed as a part of engineering education program of combustion and propulsion classes. Combustor pressure is predicted by the chemical equilibrium analysis of a constant volume combustor. Then, the internal ballistics, the conversion of thermal energy into the mechanical energy of a projectile, is predicted though the expansion process. The trajectory of a projectile is estimated by considering the aerodynamic effect around the spherical projectile. The energy conversion efficiency and the equivalence ratio of the fuel-air mixture could be estimated by the comparison of the experimental results and the theoretical prediction. The present work would be an example of attracting the interest of students for the application of the engineering principles at undergraduate level by recycling the waste materials.

An Experimental Study on the Ready-Mixed Concrete Manufacture Performance of Ultra-High Strength Concrete using the Crushed Sand (부순모래를 사용한 초고강도 콘크리트의 레미콘 제조성능에 관한 실험적 연구)

  • Rho, Hyoung-Nam;Lim, Hyon-Ung;Choi, Se-Jin;Lee, Seong-Yeon;Lee, Sang-Soo;Song, Ha-Youg
    • Proceedings of the Korean Institute of Building Construction Conference
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    • 2007.04a
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    • pp.25-28
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    • 2007
  • In this study we measured the changes according to time respectively on the basis of 0, 30, 60 and 90 minutes, taking into consideration the decline in fluidity of concrete according to elapsed time to analyze manufacturing capability of batcher plant according to elapsed time of ready-mixed concrete manufactured in batcher plant, and offer basic data for mixture design of ultra-high strength concrete. The proportion of water-binder was 23.55, water content was 160kg/m3, proportion of replacement of crushed sand was 0, 20 and 40% at 3 level, and we applied to the same condition of triaxial component using blast furnace slag powder and silica fume as admixture. And to meet the demand of certain fluidity, we measured respectively on property before and after hardening of ultra-high strength concrete using superplasticizer. As a result of experiment, before hardening of ultra-high strength concrete showed the best fluidity in conditions of crushed sand replacement rates of 20% and superplasticizer composition of 1.95%, but it appeared that fluidity drops as time goes by in the same composition condition. And it appeared that when it comes to hardened, the changes of compression strength according to elapsed time by crushed sand replacement rates were within 1MPa. Therefore, it turned out that the difference of strength according to elapsed time was low and compression strength of 280dys in composition mentioned above appeared highly as 88MPa.

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Optimization of the Extrusion Processing Conditions of Soymilk Residue and Corn Grits Mixture (두유박과 옥분 혼합물 압출성형 제조공정의 최적화)

  • 한규홍;김병용
    • Journal of the Korean Society of Food Science and Nutrition
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    • v.32 no.8
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    • pp.1270-1277
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    • 2003
  • The extrusion conditions of the soymilk residue and corn grits mixtures were optimized. The experiment was designed according to the D-optimal design of response surface methodology (RSM), which shows 18 experimental points including 4 replicates for three independent variables (screw speed, water content and die temperature). The responses variables such as bending force, expansion ratio, bulk density, water solubility index (WSI), water absorption index (WAI), and color values (L*, a*, b*) were evaluated using response surface analysis. Expansion ratio and WSI decreased with increasing water content, whereas bulk density tended to increase with increasing water content. While greater screw speeds enhanced WSI and yellowness, higher moisture contents decreased the expansion ratio and WSI value. However, die temperature did not influence upon the response variables. The optimum extrusion conditions by numerical and graphical methods were similar: the screw speed, water content, and die temperature were 250 rpm, 22.43% and l28.16$^{\circ}C$ by the numerical method; 250 rpm, 22.43%, and 128.02$^{\circ}C$ by graphical method.

Development Ultra Rapid Hardening Construction Materials on Cold Weather Environment Considering Curing Temperature (양생온도를 고려한 극한지용 초속경 건설재료 개발)

  • Cho, Hyun-Woo;Shin, Hyun-Seop;Lee, Jang-Hwa
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.17 no.5
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    • pp.59-66
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    • 2013
  • Because ordinary concrete cannot be hardened well under sub-zero temperatures, anti-freeze agents are typically added to prevent the frost damage and to ensure the proper hardening of concrete. With the advantage of a rapid exothermic reaction property, jet set concrete may be used as a cold weather concrete because it can reach the required strength before being damaged by cold weather. Recent studies are reported that magnesia-phosphate composites can be hardened very quickly and hydrated even in low temperature, which can be used as an alternative of severe cold weather concrete in arctic regions. This study developed the magnesia-phosphate composites that can be used in severe cold regions and suggested an appropriate mixture design from the experimental results.

One-Dimensional Modeling of Hydrogen Generator (수소발생기의 일차원 모델링)

  • Park, Jae Hyun;Lee, Hyojin;Valderrama, Edgar Willy Rimarachin;Yim, Chungsik;Yang, Heesung
    • Journal of the Korean Society of Propulsion Engineers
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    • v.22 no.2
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    • pp.74-86
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    • 2018
  • This paper presents the one-dimensional model of a hydrogen generator, where the alkali solution was supplied from the top to the dry aluminum powders. Hydrogen was produced as the solution moved downward and reacted with aluminum. The species conservation equations were considered for the hydrogen gas and alkali solution, while the energy conservation equation was applied to the gas-liquid-solid mixture as a single medium. The gas rising velocity and liquid penetration velocity were also included in the theoretical approach. The developed code was validated with the experimental data of the hydrogen production amount and collector pressure. Additionally, the model successfully predicted the various reactor properties, such as the concentrations, volume fractions, and temperatures, and is expected to help significantly in the design of a novel hydrogen generator.

Suggesting a new testing device for determination of tensile strength of concrete

  • Haeri, Hadi;Sarfarazi, Vahab;Hedayat, Ahmadreza
    • Structural Engineering and Mechanics
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    • v.60 no.6
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    • pp.939-952
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    • 2016
  • A compression to tensile load transforming (CTT) device was developed to determine indirect tensile strength of concrete material. Before CTT test, Particle flow code was used for the determination of the standard dimension of physical samples. Four numerical models with different dimensions were made and were subjected to tensile loading. The geometry of the model with ideal failure pattern was selected for physical sample preparation. A concrete slab with dimensions of $15{\times}19{\times}6cm$ and a hole at its center was prepared and subjected to tensile loading using this special loading device. The ratio of hole diameter to sample width was 0.5. The samples were made from a mixture of water, fine sand and cement with a ratio of 1-0.5-1, respectively. A 30-ton hydraulic jack with a load cell applied compressive loading to CTT with the compressive pressure rate of 0.02 MPa per second. The compressive loading was converted to tensile stress on the sample because of the overall test design. A numerical modeling was also done to analyze the effect of the hole diameter on stress concentrations of the hole side along its horizontal axis to provide a suitable criterion for determining the real tensile strength of concrete. Concurrent with indirect tensile test, the Brazilian test was performed to compare the results from two methods and also to perform numerical calibration. The numerical modeling shows that the models have tensile failure in the sides of the hole along the horizontal axis before any failure under shear loading. Also the stress concentration at the edge of the hole was 1.4 times more than the applied stress registered by the machine. Experimental Results showed that, the indirect tensile strength was clearly lower than the Brazilian test strength.

Evaluation of acetaldehyde removal performance of a hybrid adsorbent consisting of organic and inorganic materials (유무기 융복합 흡착제의 아세트알데하이드 제거 성능 평가)

  • Ahn, Hae Young;Lee, Yoon Kyoung;Song, JiHyeon
    • Journal of odor and indoor environment
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    • v.17 no.4
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    • pp.372-380
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    • 2018
  • To abate the problem of odor from restaurants, a hybrid adsorbent consisting of organic and inorganic materials was developed and evaluated using acetaldehyde as a model compound was deveioped and evaluated. Powders of activated carbon, bentonite, and calcium hydroxide were mixed and calcinated to form adsorbent structure. The surface area of the hybrid adsorbent was smaller than that of high-quality activated carbon, but its microscopic image showed that contours and pores were developed on its surface. To determine its adsorption capacity, both batch isotherm and continuous flow column experiments were performed, and these results were compared with those using commercially available activated carbon. The isotherm tests showed that the hybrid adsorbent had a capacity 40 times higher than that of the activated carbon. In addition, the column experiments revealed that breakthrough time of the hybrid adsorbent was 2.5 times longer than that of the activated carbon. These experimental results were fitted to numerical simulations by using a homogeneous surface diffusion model (HSDM); the model estimated that the hybrid adsorbent might be able to remove acetaldehyde at a concentration of 40 ppm for a 5-month period. Since various odor compounds are commonly emitted as a mixture when meat is barbecued, it is necessary to conduct a series of experiments and HSDM simulations under various conditions to obtain design parameters for a full-scale device using the hybrid adsorbent.

Potential use of Flemingia (Flemingia macrophylla) as a protein source fodder to improve nutrients digestibility, ruminal fermentation efficiency in beef cattle

  • Phesatcha, Burarat;Viennasay, Bounnaxay;Wanapat, Metha
    • Animal Bioscience
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    • v.34 no.4
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    • pp.613-620
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    • 2021
  • Objective: This study aimed at studying the potential use of Flemingia (Flemingia macrophylla) as a protein source fodder to improve nutrients digestibility and ruminal fermentation efficiency in beef cattle. Methods: Four, Thai native beef cattle were randomly assigned in a 4×4 Latin square design. Four levels of Flemingia hay meal (FHM) were used to replace soybean meal (SBM) in the concentrate mixtures in four dietary treatments replacing levels at 0%, 30%, 60%, and 100% of SBM. Results: The experimental findings revealed that replacements did not effect on intake of rice straw, concentrate and total dry matter (DM) intake (p>0.05). However, the apparent digestibilities of DM, organic matter, crude protein, acid detergent fiber, and neutral detergent fiber were linearly increased up to 100% replacement levels. Moreover, the production of total volatile fatty acids, and propionate concentration were enhanced (p<0.05) whereas the concentration of acetate was reduced in all replacement groups. Consequently, the CH4 production was significantly lower when increasing levels of FHM for SBM (p<0.05). Furthermore, rumen bacterial population was additionally increased (p<0.05) while protozoal population was clearly decreased (p<0.05) in all replacement groups up to 100%. In addition, microbial nitrogen supply and efficiency of microbial nitrogen synthesis were enhanced (p<0.05), as affected by FHM replacements. Conclusion: The findings under this experiment suggest that 100% FHM replacement in concentrate mixture enhanced rumen fermentation efficiency, nutrients digestibilities, bacterial population, microbial protein synthesis, and subsequently reduced CH4 production in beef cattle fed on rice straw.

Evaluation of failure mode of tunnel-type anchorage for a suspension bridge via scaled model tests and image processing

  • Seo, Seunghwan;Lim, Hyungsung;Chung, Moonkyung
    • Geomechanics and Engineering
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    • v.24 no.5
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    • pp.457-470
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    • 2021
  • In this study, the pull-out behavior of a tunnel-type anchorage for suspension bridges was investigated using experimental tests and image processing analyses. The study focused on evaluating the initial failure behavior and failure mode of the tunnel-type anchorage. In order to evaluate the failure mode of tunnel-type anchorage, a series of scaled model tests were conducted based on the prototype anchorage of the Ulsan Grand Bridge. In the model tests, the anchorage body and surrounding rocks were fabricated using a gypsum mixture. The pull-out behavior was investigated under plane strain conditions. The results of the model tests demonstrate that the tunnel-type anchorage underwent a wedge-shaped failure. In addition, the failure mode changed according to the differences in the physical properties of the surrounding rock and the anchorage body and the size of the anchor plate. The size of the anchor plate was found to be an important parameter that determines the failure mode. However, the difference in physical properties between the surrounding rock and the anchorage body did not affect its size. In addition, this study analyzed the initial failure behavior of the tunnel-type anchorage through image analysis and confirmed that the failure was sequentially transferred from the inside of the tunnel to the surrounding rock according to the image analysis. The reasonable failure mode for the design of the tunnel-type anchorage should be wedge-type rather than pull-out type.