• 대한기계학회논문집
• /
• 제15권1호
• /
• pp.252-261
• /
• 1991

본 연구에서는 2상 횡분류의 평균 유동특성을 비교적 정확히 예측할 수 있는 방법을 제시하는데 있다. 이를 위하여 2상 기체 분류속에 유입되는 자유흐름의 질량 유입을 Keffer와 Baines의 유입함수를 이용하기로 하며, 입자와 기체분류사이의 궤적 이탈을 고려하기로 한다. 이런 모델을 이용하여 2상 횡분류의 분출초기의 입자와 기 체분류의 속도비(particle to gas velocity ratio at the jet exit)가 유동에 미치는 영향을 알아보고자 한다.

• 한국콘크리트학회:학술대회논문집
• /
• 한국콘크리트학회 2001년도 가을 학술발표회 논문집
• /
• pp.123-128
• /
• 2001

The Purpose of this study is to clarify the effect of the monomer ratio on properties of the polymer-modified mortars using methyl methacrylate-butyl acrylate latexes, and to obtain basic data necessary to develop appropriate latexes for cement modifiers. This paper deals with the effect of the monomer ratio on the typical properties of polymer-modified mortars with methyl methacrylate-butyl acrylate latexes. The polymer latex-modified mortars are prepared with 5, 10, IS and 20% of polymer cement ratio respectively, and properties of modified mortars such as water absorption, compressive and flexural strengths, chloride-ion penetration depth are tested. The test results indicate that the monomer ratio is very important factors to characterize the strength properties of polymer-modified mortars, but the water absorption and chloride-ion penetration depth are influenced by polymer-cement ratio rather than monomer ratios.

• Journal of Welding and Joining
• /
• 제35권1호
• /
• pp.74-78
• /
• 2017

In auto ancillary fabrication industry, GMAW is a very useful & important welding process and EN10025 S 235 Grade is common material used for manufacturing of two wheeler chassis. This research gives the detail influence of welding process parameters such as welding current, welding voltage, wire speed on the penetration in EN10025 S 235 Grade mild steel material. The experimentation of this research has been carried out by using three factors, three level Taguchi DOE method. To analyze & optimize the welding parameters & characteristics, analysis of variance, L9 orthogonal array & signal to noise ratio are used. Length of Penetration in addition to the depth of penetration is major concern in fillet welded joints, as the penetration decides the strength of the welded joint. After analysis of penetration in all 9 welded samples, optimize parameters readings verified & found probability value within 0.05.From this research it is come to know that welding current & welding voltage is major parameters which affects the penetration in welded joints.

• 한국지반환경공학회 논문집
• /
• 제22권1호
• /
• pp.13-20
• /
• 2021

A suite of 3D large deformation finite element (FE) analyses was performed to investigate the load transfer mechanism and penetration resistance of spudcan foundations in heterogeneous soil profile consisting of sand and clay. The Elasto-Plastic models following Mohr-Coulomb and Tresca failure criteria were adopted for sand and clay, respectively. The accuracy of the numerical model was validated against centrifuge test measurements. The dense sand behavior with dilation is modeled using the non-associated flow rule. An investigation study consisting of key parameters, which includes variation in soil stratigraphy (sand-clay, sand-clay-sand), strength parameters of sand and clay (��' and su) and normalized height ratio of the sand layer (Hs/D) was conducted to assess the penetration behavior of spudcan. Based on calculated outputs, it was demonstrated that these parameters have a significant influence on the penetration resistance of spudcan. The calculated penetration resistance profiles are compared with the published (sand overlying clay) analytical model. It is confirmed that for the case of two-layer soil, the available theoretical model provides an accurate estimate of peak penetration resistance (qpeak). In the case of three-layer soil, the presence of a third stiff layer affects the penetration resistance profile due to the squeezing of the soil.

• 한국분무공학회지
• /
• 제10권1호
• /
• pp.35-42
• /
• 2005

The present study has numerically and experimentally investigated the spray behavior of liquid jet injected in subsonic cross-flow. The corresponding spray characteristics are correlated with jet operating parameters. The spray dynamics are known to be distinctly different in the three regimes: the column, the ligament and the droplet regimes. The behaviors of column, penetration and breakup of liquid jet have been studied. Numerical and physical models are base on a modified KIVA code. The primary atomization is represented by a wave model base on the KH(Kelvin-Helmholtz) instability that is generated by a high interface relative velocity between the liquid and gas flows. In odor to capture the spray trajectory, CCD camera has been utilized. Numerical and experimental results indicate that the breakup point is delayed by increasing gas momentum ratio and the penetration decreases by increasing Weber number.

• 한국레이저가공학회지
• /
• 제1권1호
• /
• pp.30-38
• /
• 1998

This study includes the efface of shielding gas types on $CO_2$ laser weldability of low carbon automotive galvanized steel. The types of shielding gas evaluated are He, $CO_2$, Ar, $N_2$, 50%Ar＋50%$N_2$. The weld penetration, strength, formability(Erichsen test) of Laser weld are found to be strongly dependent upon the types of shielding gas used. Further, the maximum travel speed and flow rate to form a keyhole weld is also dependent upon types of shielding gas. The ability of shielding gas in removing plasma plume and thus increasing weld penetration is believed to be closely related with ionization/dissociation potential, which determine the period of plasma formation and disappearance. Further, thermal conductivity and reactivity of gas with molten pool also give strong effect on penetration and porosity formation which in turn affect on the formability and strength.

• 한국콘크리트학회:학술대회논문집
• /
• 한국콘크리트학회 2004년도 춘계 학술발표회 제16권1호
• /
• pp.838-841
• /
• 2004

This paper presents the experimental results on the penetration of chloride. ions to ordinary portland cement concrete which is subjected to 2 different artificial environments; consecutive digestion, wetting at $3\%$ NaCl for 1 day and then drying at $40^{\circ}C$ oven for 4 days. The water-cement ratio was $35\%,\;45\%,\;55\%$. Test results showed that the intrusion depth and concentration of chloride ions penetrated into concrete in repeated wetting-drying environments were respectively deeper and higher than those of consecutive digestion environment. The penetration of chloride ions deeply depend on the effect of water to cement ratio.

• Macromolecular Research
• /
• 제13권2호
• /
• pp.107-113
• /
• 2005

We developed an algorithm to simulate the generation of virtual nanowebs using the Monte Carlo method. To evaluate the pore size of the simulated multi-layered nanoweb, an estimation algorithm was developed using a ghost particle having zero volume and mass. The penetration time of the ghost particle through the virtual nanoweb was dependent on the pore size. By using iterative ghost particle penetrations, we obtained reliable data for the evaluation of the pore size and distribution of the virtual nanowebs. The penetration time increased with increasing number of layers and area ratio, whereas it decreased with increasing fiber diameter. Dimensional analysis showed that the penetration time can be expressed as a function of the fiber diameter, area ratio and number of layers.

• 한국해안해양공학회지
• /
• 제9권4호
• /
• pp.165-175
• /
• 1997

본 연구에서는 재하높이와 근입비를 달리하는 근입식 강판셀의 모형실험을 실시하여 셀 구조물의 변형특성에 미치는 재하높이와 근입비의 영향을 정성적으로 검토하였다. 또한, 채움재로 알루미늄 봉을 이용한 2차원 모형실험을 수행하여 채움재의 전단거동에 미치는 재하높이의 영향을 검토하고, Hansen의 토압이론에 근거하여 실험치와 이론치를 비교·검토하였다. 그 결과, 재하높이와 근입비에 따라 셀의 항복모벤트가 달라진다는 사실을 확인할 수 있었으며, 활동면은 재하높이가 낮아짐에 따라 셀 내부의 보다 낮은 곳에 위치함을 알 수 있었다. 그리고 Hansen의 토압이론에 의하여 이론적인 고찰을 수행한 결과, 실험치와 이론치는 비교적 잘 일치하였으며, 재하높이에 따른 활동면의 위치변화에 대해서는 동일한 결과를 얻었다.

• 한국자동차공학회논문집
• /
• 제18권3호
• /
• pp.80-87
• /
• 2010

The purpose of this paper is to analyze the effects of ethanol blending ratio and fuel temperature in diesel-ethanol blended fuel on the spray-atomization characteristics in a high pressure common-rail injection system. In this work, a diesel fuel and three blended fuels were used as test fuels. Blended fuels were made by blending ethanol with a purity 99.9% to diesel fuel, from 0% to 30%. In order to keep diesel-ethanol blending stability, 5% of biodiesel fuel as volumetric ratio was added into test fuels. The fuel temperature was controled in steps with 40K, from 290K to 370K. Macroscopic spray characteristics were investigated by analyzing the spray tip penetration and spray cone angle through spray images obtained from visualization system. In addition, in order to study microscopic spray characteristics of ethanol blended fuels, the droplet diameter, was analyzed using the droplet measuring system. It is revealed that the spray tip penetration is similar regardless of ethanol blending ratio. As ethanol blending ratio is increased, the spray cone angle becomes wider. It is shown that the spray cone angle is affected by low viscosity and density of ethanol. As the fuel temperature increases, the spray tip penetration and spray cone angle become shorter and narrower respectively. The SMD of ethanol blending fuels is smaller than that of diesel fuel because of low viscosity and surface tension of ethanol.