• Nuclear Engineering and Technology
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• 제38권7호
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• pp.681-688
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• 2006

This study investigates the dynamic response characteristics of a structure impacted by a high speed projectile. The impact of a 300 kg projectile on a water storage tank is simulated by the general purpose computer codes ANSYS and LS-DYNA. Several methods to simulate the impact are considered and their results are compared. Based upon this, an alternative impact analysis method that is equivalent to an explicit dynamic analysis is proposed. The effect of fluid on the responses of the tank is also addressed.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2001년도 춘계학술대회 논문집
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• pp.1004-1007
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• 2001

This paper presents the experimental results to verify the environmental consciousness with economic balances due to cutting fluid behaviors, effectiveness in machining process. Even though cutting fluid improves the machined part quality through the cooling and lubracating effects, its environmental impact is also increased according to the cutting fluid usage. Because cutting fluid are used by experience than science on shop floors, its environmental impact are more serious to human health hazard, shop floor environments. In this study a few cutting parameters are adopted as the machinability index (i.e. ; tool wear and surface roughness), and aerosol mist diffusion rate of cutting fluid as the environment consciousness index. These indeces are analyzed quantitatively via a few experiements. The results of this study can be facilitate the optimization of cutting fluid usage in achieving a balanced environmental consciousness consideration with economic view.

• 대한기계학회논문집B
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• 제27권6호
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• pp.744-752
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• 2003

A level set method is combined with the volume-of-fluid method so that the coupled method can not only calculate an interfacial curvature accurately but also can achieve mass conservation well. The coupled level set and volume-of-fluid(CLSVOF) method is efficiently implemented by employing an interface reconstruction algorithm which is based on the explicit relationship between the interface configuration and the fluid volume function. The CLSVOF method is applied for numerical simulation of droplet impact on solid surfaces with variable contact angles. The numerical results are found to preserve mass conservation and to be in good agreement with the data reported in the literature. Also, the present method proved to be applicable to the complex phenomena such as breakup and rebound of a droplet.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2000년도 추계학술대회 논문집
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• pp.854-857
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• 2000

This paper presents the experimental results of relationship between the machinability and environmental consciousness due to cutting fluid atomization in machining process. Even though cutting fluid improves the machined part quality through the cooling and lubracating effects, its environmental impact is also increased according to the cutting fluid usage. Cutting tool wear is one of criterion for deciding the machinability. A few turning operations were performed to know the qualitative effectiveness of cutting fluid to tool wear improvement. This research can be used as a basis for environmental impact analysis on the shop floor. It can be also facilitate the optimization of cutting fluid usage in achieving a balanced consideration of productivity and environmental consciousness.

• 한국전산구조공학회논문집
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• 제23권6호
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• pp.675-682
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• 2010

The flood impact pressure acting on a vertical wall resulting from a dam-breaking problem is simulated using a navier-Stokes(N-S) solver. The N-S solver uses Eulerian Finite Volume Method(FVM) along with Volume Of Fluid(VOF) method for 2-D incompressible free surface flows. A Split Lagrangian Advection(SLA) scheme for VOF method is implemented in this paper. The SLA scheme is developed based on an algorithm of Piecewise Linear Interface Calculation(PLIC). The coupling between the continuity and momentum equations is affected by using a well-known Semi-Implicit Method for Pressure-Linked Equations (SIMPLE) algorithm. Several two-dimensional numerical simulations of the dam-breaking problem are presented to validate the accuracy and demonstrate the capability of the present algorithm. The significance of the time step and grid resolution are also discussed. The computational results are compared with experimental data and with computations by other numerical methods. The results showed a favorable agreement of water impact pressure as well as the global fluid motion.

• 한국정밀공학회지
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• 제22권6호
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• pp.61-69
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• 2005

This paper presents the experimental results to analyze the atomization characteristics and environmental impact of cutting fluid in grinding process. Grinding is a major machining process to improve surface quality with different machining mechanism which is compared with turning or milling process. The environmental impact due to aerosol generation via grinding process is a major concern associated with environmental consciousness. Experimental results show that the generated fine aerosol which particle size less than 10 micron appears near working zone under given operational conditions. The aerosol concentration is much higher enough to affect human health risk with its generated aerosol quantities. This study can be provided a basic knowledge fur further research of environmental consciousness machining development.

• 대한의용생체공학회:의공학회지
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• 제13권4호
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• pp.285-298
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• 1992

An analysis of the dynamics in the closing phase of the occluder of a mechanical monoleaflet heart valve prosthesis is presented. The dynamic analysis of the fluid in the vicinity of the occluder was based on the control vo]use approach. The backflow velocity of the fluid was computed by applying the continuity, Bernoulli's and momentum equations in the unsteady state. By considering the fluid pressure and gravity as external forces acting on the occluder, the moment equilibrium on fine occluder was employed to analyze the motion of the occluder during closing and the force of impact between the occluder and the guiding struts. Occluder comes to rest after several oscillations in about 10-18 msec after the Inltiaton of closing. As the aortic pressure increases, the occludes closes faster and comes to the final resting position earlier and the impact force increases also. But backflow is not af footed by the variation of the aortic pressure. With decreasing time delay of the ventricle pressure, the occluder closes faster and impact force Increases. The computed magnitudes of the occluder tiP velocities as well as the backflow of the fluid during the closing phase using this model were in agreement with previously reported experimental measurements.

• 유공압시스템학회논문집
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• 제4권4호
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• pp.21-27
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• 2007

A hydraulic breaker for construction machinery generally used for the destroying and disassembling of buildings, crashing road pavement, breaking rocks at quarry and so on. So the measurement of the impact energy of a hydraulic breaker is very important thing to prove its capability to manufacturers and customers. Therefore the prediction of impact energy in design process is very helpful to the most of breaker manufacturers. In this study, we carried on modeling and simulation of a hydraulic breaker to predict impact energy via commercial CAE software. The modeling and simulation of a hydraulic breaker was achieved with two parts. One is a hydraulic circuit analysis part via AMESim and the other is impact strain analysis part via ANSYS.

• Journal of Advanced Marine Engineering and Technology
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• 제39권4호
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• pp.489-494
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• 2015

본 연구의 목적은 선박의 충돌에 의해 발생하는 원형단면을 갖는 실린더형 해양구조물의 충격손상을 최소화 시키기 위한 것이다. 기존의 설계기준, 코드 및 선급규정 등에 명시된 충격해석은 해수유체영역이 고려되지 않은 상태로 계산을 수행해 왔다. 본 연구에서는 해수유체영역을 고려한 모델링방법과 동적응답, 변형률, 내부에너지 등의 응답파라미터를 고찰하여 기존에 고려하지 않은 결과와 비교분석하였다. 충돌선박의 선속을 변화시켜 다양한 상태의 하중케이스를 고려하였고 가장 큰 충격하중상태인 2.0m/s에서의 선속에서의 응답결과를 비교분석하였다. ALE방법을 이용하여 해수유체영역을 고려한 경우 해수영역에서의 충격에너지 흡수와 유체감쇠를 통해 응답크기가 더 작고 구조물의 응력과 소성영역의 분포가 고르게 나타났다. 해수유체영역을 고려하지 않은 경우 보다 보수적인 설계가 될 수 있음을 알 수 있었다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2002년도 춘계학술대회 논문집
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• pp.943-946
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• 2002

This paper presents atomization characteristics of cutting fluids. To analyze the behavior characteristics of cutting fluid, analytical approach and experimental measurement were performed to predict the aerosol size, velocity and concentration due to cutting fluid atomization mechanism in machining operation. The established analytical model which is based on atomization theory analyzes the cutting fluid motion and aerosol generation in machining process. The predictive models can be used as a basis for environmental impact analysis on the shop floor. It can be also facilitate the optimization of cutting fluid usage in achieving a balanced consideration of productivity and environmental consciousness.