• Journal of the Korean Society for Heat Treatment
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• v.11 no.2
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• pp.131-139
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• 1998

The object of this research is to estimate the hardenability of quenched carbon steels AISI 1050. The equation of transient heat conduction was analyzed to derive cooling curve by finite element method. The effects of temperature on physical properties, metallic structures and the latent heat by phase transformation were considered. A good agreement was found between analytical and experimental results to show that the proposed numerical procedure was reliable. This procedure could be used as the detabase for optimal condition of heat treatment cycle.

• Proceedings of the KSME Conference
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• 2001.06d
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• pp.79-84
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• 2001

The effect of spray characteristics on desulfurization yield was evaluated by performing experiments with pilot spray drying sorber (SDS). Among the variables of operating conditions, the slurry-spraying conditions were chosen as major parameters; Stoichiometric ratio and Sauter mean diameter of slurry droplet were varied for the different gas temperatures and $SO_{2}$ concentrations in the inlet gas flow. From the experimental results, we proposed semi-empirical models of desulfurization yield for both Stoichiometric ratio and Sauter mean diameter of droplets. The optimal condition of spray can be determined based on these results, which might be applied to the design or scale-up of SDS systems.

• Proceedings of the KSME Conference
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• 2001.06d
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• pp.31-36
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• 2001

As a part of micro engine development feasibility estimation was done through fabrication and test of down scaled combustor and MEMS fabricated spark electrode. In an experimental observation of the down scaled combustion phenomena where flame propagation was observed by optical method and pressure change in combustor which gives the information about the reaction generated thermal energy was recorded and analyzed. Optimal combustor scale was derived to be about 2mm considering increased heat loss effect and thermal energy generation capability. Through the fabrication and discharge test of MEMS electrode effects of electrode width and gap was investigated. Electrode was fabricated by thick PR mold and electroplating. From the result discharge voltage characteristic in sub millimeter scale electrode having thickness of $40{\mu}m$ was obtained. From the result base technology for design and fabrication of micro engine was obtained.

• Journal of the Korean Society for Precision Engineering
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• v.5 no.3
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• pp.31-42
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• 1988

This paper describes a computer aided process planning system called "Deep-Drawing", "Deep-Drawing" is designed for the drawing sequence of cylindrical and rectangular cups with or without taper and flange. The computer program has written in BASIC language with personal computer. Design Rules for process planning are formulated from process limitation, plasticity theory and experimental results including the know-how of many manufacturing factories. "Deep-Drawing" Capabilities include the analysis of drawing sequence by the determination of optimal drawing ratio, the determination of intermediate shape, dimensions, punch and die radius etc., the calculation of drawing loads and blank holder force to perform each drawing step, and the graphic outputs for the operation sheet.tputs for the operation sheet.

• The Transactions of the Korean Institute of Power Electronics
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• v.4 no.2
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• pp.111-121
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• 1999

This paper deals with an active gate drive (AGD) technolo밍T for high power IGBTs. It is based on an optimal c combination of several requirements necessmy for good switching performance under hard switching conditions, The s scheme specifically combines together the slow drive requirements for low noise and switching stress and the fast driver requirements for high speed switching and low switching energy loss The gate drive can also effectively dampen oscillations during low cunent turnlongrightarrowon transient in the IGBT, This paper looks at the conflicting requirements of the c conventional gate dlive circuit design and the experimental results show that the proposed threelongleftarrowstage active gate dlive t technique can be an effective solution.

• 한국생물공학회:학술대회논문집
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• 2001.11a
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• pp.81-84
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• 2001

A real time optimization algorithm for fed-batch cultures of recombinant yeast to determine the optimal substrate feed rate profile has been developed. Its development involved four key steps: (1) development of reliable adaptive model. (2) development of optimization algorithm. (3) design of on-line model update algorithm to be incorporated into the optimization algorithm and (4) experimental validation. A recombinant Saccharomyces cerevisiae producing human parathyroid hormone (hPTH) was chosen as the model strain. It was found to be very successful in maintaining cell growth and galactose consumption at leigh levels, thus resulting in significant improvements in the productivity (up to 2.1 times) and intact hPTH concentration (up to 1.5 times) compared with the case of an intermittent glucose and galactose, or galactose feeding.

• 한국생물공학회:학술대회논문집
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• 2003.10a
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• pp.273-277
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• 2003

Batch culture of mutant derived from Pichia ciferrii ATCC 14091 was investigated for producing the intracellular tetraacetylphytosphingosine (TAPS). Composite experimental design was used to optimize the composition of the culture medium for maximizing the productivity of TAPS. In this experiment, various culture parameters were investigated that were the effects of temperature, the initial culture pH, the carbon-to-nitrogen ratio, the concentration of trace elements, and the concentration of cofactors. The optimal temperature for cell growth and TAPS synthesis appeared to be %25^{\circ}C$. An initial pH value of 7.5 gave the best results. Under the best condition, the maximum TAPS concentration indicated 7.2 g/L and its productivity was 0.06 g/L-hr in a 2.5 L jar

• Transactions of the Korean Society of Mechanical Engineers A
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• v.22 no.4
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• pp.859-867
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• 1998

An oil lubricated Herringbone aroove jounal bearing(HGJB) with eight-circular-profile grooves on the non-rotating bearing surface is analyzed numerically and experimentally. The load carrying capacity, attitude angle, stiffness and damping coefficients are obtained numerically for the various bearing configurations. The onset speed of instability is also examined for the various eccentricity ratios. The configuration parameters of HGJB, such as groove depth ratio, groove width ratio, and groove angle, are dependent on each other because the grooves are generated by using eight small balls rolling over the inner surface of the sleeve with press fit. Therefore, it is not allowed to suggest a set of optimal design parameters such as the one for the rectangular profile HGJB. The overall results from numerical and experimental analysis prove that the circular profile HGJB has an excellent stability characteristics and the higher load carrying capacity than the plain journal bearing.

• 한국생물공학회:학술대회논문집
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• 2003.04a
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• pp.153-156
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• 2003

The MRS medium is widely used as an optimized medium for the growth of Lactobacillus spp. and also used for the growth of Leuconostoc spp. Leuconostoc mesenteroides shows quite different physicochemical properties compared to Lactobacilli spp. and it is one of the major strain of kimchi fermenting microorganisms with its usefulness in our traditional foods and availability in biotechnology in the future, specifically tailor-made medium is necessary for the growth of Leuconostoc mesenteroides. Sequential experimental designs (Plackett-Burman, fractional factorial, steepest ascent, central composite design and response surface methodology) were introduced to optimize and improve the Leuconostoc medium. Fifteen medium ingredients were investigated and fructose, sodium acetate and ammonium citrate were determined to give a critical and positive effect for cell-growth. The yield of biomass using the optimal medium was improved more than that of the MRS medium and the result of fed-batch culture showed the capability of the improvement in cell mass similar to the E.coli system.

• Transactions of the Korean Society of Mechanical Engineers
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• v.15 no.2
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• pp.661-667
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• 1991

A performance of a regenerative pump has been analyzed using various pressure loss correlations. The predicted head and efficiency agree favorably with experimental data, which confirms the validity of the present analysis. In addition, performance improvement is made through the optimization of the open channel geometry configuration and the capacity of the regenerative pump. The optimized pump has better efficiency, higher head and larger flow coefficient. Moreover, its operation range is wider than that of the conventional unit.