• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1994.03a
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• pp.149-158
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• 1994

Powder forged Connecting Rods have become attractive for use in automotive engines. The powder forging process offers beneficial material utilization as well as the minimization of finishing operations over that of conventionally forged rods. In the present work, the sintering behavior of Fe-2Cu-0.6C, optimum preform design and forgeability of various forging variables were investigated. Our data were generated using a newly proposed sub-scale con-rod developed specifically to simulate the powder forging process. We obtain optimum condition of sintering and powder forging process.

• Molecular & Cellular Toxicology
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• v.3 no.2
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• pp.77-84
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• 2007

Millions of individuals worldwide are currently afflicted with neurodegenerative disorders such as Parkinson's disease and multiple sclerosis which are caused by the death of specific types of specialized cells in the Central Nervous System (CNS). Recently, Neural Stem Cells (NSCs) are able to replace these dead cells with new functional cells, thereby providing a cure for devastating neural diseases. The clinical use of neural stem cells (NSCs) for the treatment of neurological diseases requires overcoming the scarcity of the initial in vivo NSC population. Thus, we developed a novel 3-dimentional cellular automata model for optimum production of neural stem cells and their derivatives in large scale to treat neurodegenerative disorder patients.

• Microbiology and Biotechnology Letters
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• v.21 no.6
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• pp.609-614
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• 1993

The optimum conditions for the submerged mycelial culture of Lentinus edodes SR-1 were elucidated to be incubation temperature of 25C, initial pH 4.0, agitation of 300 rpm, inoculation of 10.0%(v/v), and aeration of 1.0 v/v/m in TGY medium. The optimum c/n ratio and economic yield coeffcient for the submerged mycelial culture were 13.1:1 and 0.45 respectively. As the plant growth hormones test, SCM medium containing 0.5ppm of 2,4-dicholorophenoxyacetic acid increased mycelial yield in 1.1%, but 6-benzylaminopurine was not effective.

• Journal of information and communication convergence engineering
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• v.2 no.3
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• pp.177-181
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• 2004

In this paper, we suggest an Iris recognition system with an excellent recognition rate and confidence as an alternative biometric recognition technique that solves the limit in an existing individual discrimination. For its implementation, we extracted coefficients feature values with the wavelet transformation mainly used in the signal processing, and we used neural network to see a recognition rate. However, Scale Conjugate Gradient of nonlinear optimum method mainly used in neural network is not suitable to solve the optimum problem for its slow velocity of convergence. So we intended to enhance the recognition rate by using Levenberg-Marquardt Back-propagation which supplements existing Scale Conjugate Gradient for an implementation of the iris recognition system. We improved convergence velocity, efficiency, and stability by changing properly the size according to both convergence rate of solution and variation rate of variable vector with the implementation of an applied algorithm.

• Journal of Microbiology and Biotechnology
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• v.2 no.2
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• pp.98-101
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• 1992

Continuous production of fructo-oligosaccharides employing a packed bed reactor charged with immobilized cells of Aureobasidium pullulans was investigated. The optimum conditions for reactor operation were a feed concentration of 860 g/l; a feed rate, expressed as superficial space velocity of $0.2\;h^{-1}$, and a temperature of $50^\circ{C}$. Under these optimum conditions, the productivity of the reactor was $180\;g/l\cdot{h}$. Initial activity was maintained for more than 100 days. The reactor was successfully scaled up to a production scale of 1000l.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.30 no.3 s.246
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• pp.302-309
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• 2006

Effective mixing plays a crucial role in microfluidics for biochemical applications. Owing to the small device scale and its entailing the low Reynolds number, the mixing in microchannels proceeds very slowly. In this work, we optimize the configuration of obstacles in the Y-channel mixer in order to attain maximum mixing efficiency. Before the optimum design, mixing characteristics are investigated using unstructured grid CFD method. Then, the analysis method is employed to construct the approximate analysis model to be used in the optimization procedure. The main optimization tool in the present work is sequential quadratic programming method. Using this approximate optimization procedure, we may obtain the optimum layout of obstacles in the Y-channel mixer in an efficient manner, which gives the maximum mixing efficiency.

• Journal of the Korean Mathematical Society
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• v.33 no.1
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• pp.69-79
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• 1996

• Journal of the Korean Institute of Educational Facilities
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• v.17 no.2
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• pp.64-74
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• 2010

• Transactions of Materials Processing
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• v.19 no.3
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• pp.167-172
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• 2010

Roll-to-roll forming process is one of important metal processing technology because the process is simple and economical. These days, with these merits, roll-to-roll forming process is tried to be employed in manufacturing the circuit board, barrier ribs and solar cell plate. However, it is difficult to apply to the forming of micro scale or sub-micro scale pattern. In this study, the roll forming processing for the micro scale is designed and analyzed. The forming of micro pattern for small electric device such as LCD panel by incremental roll forming process is analyzed. Firstly, the optimum analysis conditions are found by several analyses. And then, formability is analyzed for various protrusion shapes at various forming temperatures. The formability is evaluated in terms of filling ratio and damage value. The filling ratio is defined from the tool geometry and critical damage is determined from the analysis of uniaxial tensile test. Finally, optimum forming conditions that guarantee the successful forming are found.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2002.09a
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• pp.239-246
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• 2002

Viscoelastic dampers are known effective devices for response reduction under earthquakes and winds. This study addresses how to design the optimum viscoelastic dampers installed at the full scale five-story steel building and novel approach to carry out the experimental work to verify the damper performance. First, an exciter of hybrid mass-type actuator is designed, which can move the building and its mathematical model is derived. The integrated system of building-actuator is experimentally analyzed for mathematical model. Second, convex model is applied for the prediction of required additional damping ratios to reduce responses below a specified target level. Chevron-type viscoelastic dampers are manufactured and installed at the first and second inter-stories, which are optimum places for response reduction. Sine-sweep and white noise excitations, which are generated by the hybrid mass-type actuator, are applied to the full scale building without and with dampers for performance verification. The transfer function of the building with four dampers, two of them installed at each first and second inter-story, are found to be lower than that of the building with two dampers installed at the first inter-story