• Journal of Mechanical Science and Technology
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• v.14 no.9
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• pp.928-934
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• 2000

This paper describes a method developed for the simulation of ring pack lubrication characteristic in an internal combustion engine. In general, the quantity of oil supply for piston ring lubrication may be insufficient in filling the entire volume formed at the interference between the piston ring and the cylinder liner. Thus the oil starvation condition should be considered in analyzing piston ring lubrication. In order to reasonably estimate the amount of oil left over on the cylinder liner, the flow rate at the posterior portion of the interface should be calculated with an adequate boundary condition that confirms flow continuity condition. In this analysis, oil starvation and open-end boundary conditions are considered at the inlet and outlet of the piston rings. The lubrication characteristic of each piston ring is obtained by an iterative method with sequential steps. It is revealed that piston rings are operated under oil starvation in most operating cycles and the result under these conditions are quite different from that with the fully-flooded assumption.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2002.04a
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• pp.206-208
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• 2002

Metalworking fluids (MWFs) are fluids used during machining and grinding to prolong the life of the tool , carry away debris, and protect the surfaces of work pieces. These fluids reduce friction between the cutting tool and the work surface, reduce wear and galling, Protect surface characteristics, reduce surface adhesion or welding and carry away generated heat. Workers can be exposed to MWFs by inhaling aerosols (mists) and by skin contact with the fluid. Skin contact occurs by dipping the hands into the fluid, splashes, or handling workpieces coated with the fluids. The amount of mist generated (and the result ins level of exposure) depends on many factors. To reduce the potential health risks associated with occupational exposures to MWFs, it is required to establish optimum MWFs supply method and condition with minimum Quantity in all over the mechanical machining field including high speed type heavy cult ing process.

• Journal of the Korean Society for Precision Engineering
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• v.26 no.2
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• pp.26-34
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• 2009

This paper is related to MQL (Minimum Quantity Lubrication) milling process, which is one of the environmentally friendly cuttings. The objective is to compare MQL milling process with conventional cutting fluid systems. To this end, machinability of MQL milling process was investigated, followed by the cost evaluation. Cutting force, surface roughness, tool wear, and cutting temperature were compared with each cutting fluid method. Consequently, total production costs wear evaluated with the mathematical models in terms of machining cost and cutting fluid loss.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.1566-1570
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• 2005

The aspherical lenses are used as optical lens of HMD optical system. The optimum cutting condition of PMMA lens sample with ultra precision SPDT, the diamond tool nose radius, the cutting speed, the feed rate, the depth of cut, and cutting fluid type are found. The demanded surface roughness 10 nm Ra, aspherical form error $1.0\;\mu{m}$ P-V for aspherical lens of optical data storage device are satisfied.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.10a
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• pp.875-880
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• 2004

Stray light is the light except the light of the analytic wavelength and the source of measurement error of absorbance. Some experimental results showed that diffractive grating is the major factor of stray light in spectrophotometer. Through the ray tracing with the software tool, classified the paths of the diffractive light from grating and found the range of wavelength which reach the exit slit. The quantity of the stray light(0.025％) is more than the minimum limit of stray light(0.01％) of the single monochromator. A novel optical layout design method, which prevent the reflected rays entering the diffractive grating is proposed.

• Korean Institute of Interior Design Journal
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• no.25
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• pp.3-10
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• 2000

In a word, Behnischs architecture can be said to be the architecture of humanism based on an interpretation of the human being. The architecture of Behnisch in which it is not space but people that becomes the subject in architecture is newness or novelty, which is proceeding to position itself as one architectural style representing the times. He refrain from the environment that is defensive and oppressive, and destructive and disruptive in composing his architecture and instead is directed towards the continuos, creative and open environment. With such an architectural language, he is pursuing a minimum of the best rather than quantity based on trust and respecting for man and nature as his unchanged theme. That is, he is seeking for the purpose of architecture that does not disregard individuality such as consumers wants and needs. As can be seen from it, his architectural work has aroused freshness and stimulus to the architectural environment that can not be boring, allowed us to look back on the architectural world and triggered our interest. His architecture has the human energy that moves us.

• Journal of Korean Institute of Industrial Engineers
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• v.24 no.1
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• pp.23-35
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• 1998

This article presents a network flow analysis to form flexible machine cells with minimum intercellular part moves and a neural network model to form part families. The operational sequences and production quantity of the part, and the number of cells and the cell size are taken into considerations for a 0-1 quadratic programming formulation and a network flow based solution procedure is developed. After designing the machine cells, a neural network approach for the integration of part families and the automatic assignment of new parts to the existing cells is proposed. A multi-layer backpropagation network with one hidden layer is used. Experimental results with varying number of neurons in hidden layer to evaluate the role of hidden neurons in the network learning performance are also presented. The comprehensive methodology developed in this article is appropriate for solving large-scale industrial applications without building the knowledge-based expert rule for the cellular manufacturing environment.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.2 no.1
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• pp.63-68
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• 2003

The aspherical lenses are used as objective lens of optical pickup. To examine the design factor the sample product is made before manufacturing of injection mould of lens. The optimum cutting condition of PMMA lens sample with ultra precision SPDT, the roam spindle speed, the depth of cut, the feedrate are found. The demanded surface roughness 100m Ra, aspherical form error $0.5{\mu}m$ P-V for aspherical lens of optical data storage device are satisfied.

• Journal of Power Electronics
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• v.14 no.6
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• pp.1314-1321
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• 2014

A new simplified topology for a dynamic voltage restorer (DVR) based on direct converter with a reduced number of switches is presented. The direct converter is fabricated using only three bi-directional controlled switches. The direct converter is connected between the grid and center-tapped series transformer. The center-tapped series transformer is used to inject the compensating voltage synthesized by the direct converter. The DVR can properly compensate for long-duration, balanced, and unbalanced voltage sag and swell by taking power from the grid. The switches are driven by ordinary pulse width modulation signals. Simulation and hardware results validate the idea that the proposed topology can mitigate sag of 50% and swell of unlimited quantity.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2003.05a
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• pp.262-269
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• 2003

Recently, a multi facility, multi product and multi period industrial problem has been widely investigated in Supply Chain Management (SCM). One of the key issues in the current SCM research area involved reducing both production and distribution costs. The purpose of this study is to determine the optimum quantity of production and transportation with minimum cost in the supply chain network. We have presented a mathematical model that deals with real world factors and constructs. Considering the complexity of solving such model, we have applied the genetic algorithm approach for solving this model computational experiments using a commercial genetic algorithm based optimizer. The results show that the real size problems we encountered can be solved In reasonable time