• 한국생물공학회:학술대회논문집
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• 2000.11a
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• pp.398-401
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• 2000

The effect of volatile components on cell growth and polysaccharide production in suspension cultures of Aloe saponaria was investigated using an intelligent on-line gas control system which enabled to control the concentrations of oxygen, carbon dioxide and ethylene simultaneously. Aloe production was enhanced in the presence of exogenous ethylene in the concentration range of 5ppm and 15ppm. Maintaining high tension of carbon dioxide (5% v/v) was found to enhance polysaccharide production significantly.

• Proceedings of the KSME Conference
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• 2000.11b
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• pp.662-667
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• 2000

A simulation procedure for a full transient analysis of the start-up of heavy-duty gas turbines for power generation is constructed. Compressor stages are grouped into three categories (front, mid, rear) and three different stage characteristic curves are applied to consider the different low-speed operating characteristics. Start-up behavior of a typical single-shaft gas turbine for power generation is simulated. The predicted transient behavior shows a good agreement with the field data. Special attention is paid to the effects of the modulation of VIGV on start-up characteristics, which play a key role in the stable operation of gas turbines.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2000.06a
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• pp.1084-1089
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• 2000

The basic equations are derived for the analysis of a stepped labyrinth gas seal which are generally used in high performance compressors, gas turbines, and steam turbines. The Bulk-flow is assumed for a single cavity control volume and the flow is assumed to be completely turbulent in circumferential direction. Moody's wall-friction-factor formula is used for the calculation of wall shear stresses in the single cavity control volume. For the reaction force developed by the seal, linearized zeroth-order and first-order perturbation equations are developed for small motion about a centered position. Integration of the resultant first-order pressure distribution along and around the seal defines the rotordynamic coefficients of the stepped labyrinth gas seal. The leakage and rotordynamic characteristic results of the stepped labyrinth gas seal are presented and compared with Scharrer's theoretical analysis using Blasius' wall-friction-factor formula.

• Transactions of Materials Processing
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• v.12 no.8
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• pp.738-743
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• 2003

The major problems of a plastic injection mould can be devided into two kinds, one is in mould another in injected parts. Most of defects of the former comes from mould design, such as, structure and working. The latter are weld line, warpage, sink mark, burning, flow mark, scratching, shading, black hole and so on. Most of problems in injection molding are difficult to find the reason because of complexity. The purpose of this paper is to improve the quality of plastic injection mould and parts with inquiring the counter plan and analizing troubles of the part of Flat TV Front Cover by flow control method and gas-assisted injection moulding. For minimizing defects of the injection moulded parts, computer aided simulation method for injection mould filling was used. Based on these numerical results, the guidelines of mould design and injection processing condition were established. As a result, the improvement of quality, such as minimizing surface defects of injection moulding parts and troubles in mould was achieved.

• 한국연소학회:학술대회논문집
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• 2012.04a
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• pp.195-196
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• 2012

This paper describes combustion tuning methodology of double-swirl gas turbine combustor using six sigma tools. This methodology is consist of five steps-Define, Identify, Design, Optimize and Verify (DIDOV). First, the NOx reduction target was defined in the step design; second, the current status of the plant was diagnosed in the step of identify; third, the vital few control parameters to achieve the defined target were determined by analyzing the correlation between the control parameters and NOx emissions in the step of design; fourth, the optimum condition was derived from one of the six sigma tools in the step of optimize; finally, the optimum condition was verified by applying the condition to the gas turbine combustor in the step of verify. As a result of the suggested method, averaged NOx emissions were reduced by more than 70% and the standard deviation was improved by more than 60%. Thus, this methodology can be attributed to the efficient reduction of NOx emission with saving combustion tuning time.

• Tribology and Lubricants
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• v.18 no.1
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• pp.24-33
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• 2002

The basic equations are derived for the analysis of a staggered labyrinth gas seal which are generally used in high performance compressors and steam turbines. The Bulk-flow is assumed for a single cavity control volume and the flow is assumed to be completely turbulent in circumferential direction. Moody's wall-friction-factor formula is used for the calculation of wall shear stresses in the single cavity control volume. For the reaction force developed by the seal, linearized zeroth-order and first-order perturbation equations are developed for small motion about a centered position. Integration of the resultant first-order pressure distribution along and around the seal defines the rotordynamic coefficients of the staggered labyrinth gas seal. Theoretical results of leakage and rotordynamic characteristics for the staggered labyrinth gas seal are compared with those of the plain seal and see-through labyrinth seal.

• 유체기계공업학회:학술대회논문집
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• 2003.12a
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• pp.80-87
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• 2003

Micro gas turbines are designed with low turbine inlet temperature and pressure ratio. To overcome the efficiency defect of the simple cycle, adoption of the recuperator is an inevitable choice. In addition to the design performance, we should also pay attention to the off-design performance of gas turbines since they usually operate at part-load conditions for a considerable amount of the time. This study aims at analyzing off-design performance characteristics of micro gas turbines and addressing the importance of the recuperator in the part load operation. Comparative analyses have been performed to evaluate the part load performance differences among various design and operating options : simple vs recuperative cycles, single vs two shaft configurations, various operating strategies for the single shaft configuration (fuel only control, variable speed operation, variable inlet guide vane control), and current vs advanced engines. Major finding is that maintaining turbine at high level is crucial in efficient operation of micro gas turbines.

• Journal of Institute of Control, Robotics and Systems
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• v.8 no.5
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• pp.407-412
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• 2002

A measurement device for gas concentration and flow rate using hot wire is developed for the utilization in industrial applications. The device has two cells of measuring and reference, and a bridge circuit is installed to detect electric current through the hot wire in the cells. An amplification of the signal and conversion to digital output are conducted for the on-line measurement with a personal computer. The flow rate of air and carbon dioxide gas is separately measured for the performance examination of the device. Also, the concentration of air-carbon dioxide and carbon dioxide-argon mixtures is determined for the same evaluation. The outcome of the performance test indicates that the accuracy and stability of the device is satisfactory for the purpose of industrial applications.

• 한국신재생에너지학회:학술대회논문집
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• 2005.06a
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• pp.273-276
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• 2005

Performance analysis of a solid oxide fuel cell/micro gas turbine hybrid system is conducted at design-point and part-load conditions and its results are discussed in this study. With detailed considerations of the heat and mass transfer phenomena along various flow streams of the SOFC, the analysis based on a quasi-2D model reasonably predicts its performance at the design-point operating conditions. In case of part-load operations, performance of the hybrid system to three different operation modes(fuel only control, speed control, and VIGV control) is compared. It is found that the simultaneous control of both supplied fuel and air to the system with a variable MGT rotational speed mode is the optimum choice for the high performance operation. And then, the dynamic characteristics of a solid oxide fuel cell are briefly introduced.

• Proceedings of the KAIS Fall Conference
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• 2006.05a
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• pp.298-301
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• 2006

DC-Motor is needed more and more sophisticated control to follow the highest precision of industrial automation and used in a number of control equipment or industrial fields. It is also useful to control single crystal($Al_2O_3$) growth. It is possible to procure a quality crystal utilizing a DC-Motor, if you mix Hydrogen and Oxygen gas properly and keep proper temperature in accordance with time process. In this paper, we will study about electrical valve positioning system for the gas mixture to improve the quality of single crystal($Al_2O_3$) growth and we will design about realtime monitoring systems of the automatic gas contol DC- Motor for single crystal($Al_2O_3$) growth