• Journal of Power System Engineering
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• v.7 no.3
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• pp.12-17
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• 2003

The purpose of this study is to observe the purification characteristics of NOx, CO and HC in various catalysts and excess air ratio conditions. For this purpose, we installed various catalysts on the back stream of the coaxial diffusion burner with swirler. As the result, in the case of NOx, Pt-Rh catalyst shows very high value that is more than 90%-conversion efficiency without the relation with the excess air ratio. After excess air ratio of ${\alpha}=1.14$, it shows that the conversion efficiencies were more than 80% in the every Pt catalyst in the view of conversion of every exhaust with changing of the excess air ratio.

• Journal of Power System Engineering
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• v.7 no.3
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• pp.18-22
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• 2003

A Study has been made to investigate the effects of hot isostatic press(HIP) and post-HIP heat treatment on microstructures and mechanical properties of Ni-based single crystal superalloy CMSX-4. HIP process was found to heal and close micropores significantly, but did not affect the morphologies of. The elimination of as-cast micropores obtained by HIP process resulted in improved stress-rupture lives of Ni-base single crystal superalloy by 185%.

• 유체기계공업학회:학술대회논문집
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• 1999.12a
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• pp.291-300
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• 1999

Currently under development is an airborne auxiliary power unit with 100 Kw equivalent power, which is composed of a centrifugal compressor, a reverse annular combustor, and a radial turbine. Air-foil bearings are used in this power unit to eliminate the oil supplying system, which can reduce the system complexity and weight. The high speed generator is adopted as an electric power generation and engine starting system, which can also eliminate the reduction gear system. Not only electric power but also pneumatic power is provided by bleeding the compressed air This power unit is aimed for the multi-purpose use such as a primary power unit In the army weapon system, an auxiliary power and environmental control unit in a next-generation tank, and a smoke generating unit.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1997.10a
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• pp.202-206
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• 1997

항공기 부품, 터빈형 임펠라나 브레이드, 자동차나 가전제품용의 대형금형류의 정밀가공과 생산성 향상에는 5축의 NC가공이 기존 3축의 NC 가공보다 많은 이점을 갖고 있다. 제1차 선도기술개발사업을 통해 C 형의 5축머시닝센터를 성공적으로 개발한 실적을 바탕으로 제2차 선도기술개발사업을 통해 작업이송거리 12,000*3,500*1,500(X*Y*Z), 위치정밀도 $\pm0.005mm/M$, 주축동력 30/45Kw의 대형, 강력, 정밀형의 문형5축머시닝센터 개불을 목표로 추진하고 있다.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2007.11a
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• pp.339-342
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• 2007

The power control system of Smart UAV is similar to the propeller pitch governing concept of turboprop aircraft. The pilot inputs the engine power directly and the pitch governor controls the propeller pitch to maintain the propeller RPM. The manual back-up system of PW206C engine is used for the engine power control of Smart UAV. Engine performance estimation program is used to predict the control range of power lever arm(PLA) angle according to the variation of flight altitude and speed. These data provide a guide for the engine control in manual mode operation.

• Journal of Power System Engineering
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• v.13 no.6
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• pp.95-101
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• 2009

The generator for gas turbine power generation consists of the rotor which generates magnetic field, the winding coil which is the path for the field current and the wedge and retaining ring which prevents the radial movement of the coil. Relatively severe deformation was observed at the coil end section during the inspection of the generator for peaking-load operation, and the thermal-electricity and the centrifugal force were evaluated by the simple modeling of the windings to find the cause. But the simulation stress was not sufficient to induce the coil plastic deformation. The analysis result seems to be applicable to the base-load generators which runs continuously without shut down up to a year, but there had been more deformation than simulated for the generator which is started up and shut down frequently. The cause of the coil deformation was the restriction of the expansion and shrinkage. The restriction occurs when the winding coil shrinks, and the stress overwhelms the yield stress and cause the plastic deformation. The deformation is accumulated during the start-ups and shut-downs and the thermal growth occurs. The factors which induce the coil restriction during the expansion and shrinkage should be reduced to prevent the unallowable deformation. The resolutions are cutting off the field current earlier during the generator shut-down, modifying the coil end section to remove the stress concentration and making the insulation plate inserted between the coil end section and the retaining ring have the constant thickness.

• Journal of Power System Engineering
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• v.14 no.4
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• pp.63-67
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• 2010

This paper introduces the eddy current signal characteristic of magnetic and non-magnetic gas turbine rotor. In the past, Magnetic particle inspection method was used in magnetic material for qualitative defect evaluation and the ultrasonic test method was used for quantitative evaluation. Nowadays, eddy current method is used in magnetic gas turbine rotor inspection due to advanced sensor design technology. We are studying on the magnetic gas turbine rotor by using eddy current method. We prepared diverse depth specimens made by magnetic and non-magnetic materials. We select optimum frequency according to material standard penetration data and experiment results. We got the signal on magnetic and non-magnetic material about 0.2 mm, 05 mm, 1.0 mm, 1.5 mm 2.0 mm and 2.5 mm depth defects and compare the signal amplitude and signal trend according to defect depth and frequency. The results show that signal amplitudes of magnetic are bigger than non-magnetic material and the trends are similar on every defect depth and frequency. The detection and resolution capabilities of eddy current are more effective in magnetic material than in non-magnetic materials. So, the eddy current method is effective inspection method on magnetic gas turbine rotor. And it has the merits of time saving and simple procedure by elimination of the ultrasonic inspection in traditional inspection method.

• Journal of Power System Engineering
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• v.13 no.5
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• pp.52-58
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• 2009

A gas turbine consists of an upstream compressor and a downstream turbine with a combustion chamber, and also the compressor and the turbine are generally coupled using a single shaft. Many casing bolts are used to assemble two horizontally separated casings, the gas turbine casing and the compressor casing, in both of axial and vertical directions. Because drilled holes for casing bolts in vertical direction are often too close to drilled holes for casing bolts in axial direction, one can observe cracks in the area frequently during operations of a gas turbine. In this study of the root cause analysis for the cracking initiating from the drilled holes of the casings of a gas turbine, the finite element analysis(FEA) was applied to evaluate the thermal and mechanical characteristics of the casings. By applying the field operation data recorded from combined cycle power plants for FEA, thermal and thermo-mechanical characteristics of a gas turbine are analyzed. The crack is initiated at the geometrical weak point, but it is found that the maximum stress is relieved when the same type of cracks is introduced on purpose during FEA. So, it is verified that the local fracture could be delayed by machining the same type of defects near the hole for casing flange bolts of the gas turbine, where the crack is initiated.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.31 no.5
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• pp.100-109
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• 2003

A performacne simulation model of the PT6A-62 turboprop engine using the $SIMULINK^R$ was proposed to predict transient and steady state behaviors. The $SIMULINK^R$ has several advantages such as user-friendliness due to the GUI(Graphic User Interfaces) and ease in the modification of the computer program. The $SIMULINK^R$ model consists of subsystems to represent engine gas path components such as flight initial subsystem, compressor subsystem, burner subsystem, compressor turbine subsystem, power turbine, exhaust nozzle subsystem and integrator subsystem. In addition to subsystems, there are search subsystems to find an appropriate operating point by scaling from the 2-D components look-up table, Gasprop Subsystem to calculate the gas property precisely. In case of steady state validation, performance results analyzed by the proposed $SIMULINK^R$ model were agreed well with the analysis results by the commercial GASTURB program. Moreover in validation of the transient model, it was found that performance simulation results by the proposed model were reasonable agreement with analysis results by the well-proved computer program using FORTRAN.

• Journal of the Korean Society of Propulsion Engineers
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• v.5 no.1
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• pp.69-75
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• 2001

Linear GPA(Gas Path Analysis) and non-linear GPA programs for performance diagnostics of a turboprop engine were developed, and a study for selection of optimal measurement variables was performed. Simultaneous faults in the compressor, the compressor turbine and the power turbine, which occur damage of the engine, were assumed. The non-linear GPA analysis was carried out with an iterative method, where the performance degradation rate of independent parameters was divided into same intervals. It was compared with the result by the Newton-Raphson method for observing the effect of an iterative method. According to the analysis result, it was found that performance of non-linear GPA can be influenced on the type of the iterative method. For showing effects of the number of measurement variables both the linear and non-linear GPAs were analyzed with 10, 8 and 6 measurement sets, respectively. RMS error between them were compared each other. It was realized that the more measurement parameters are used, and the more accurate result may be obtained. However much better result can be obtained with measurement parameters selected properly Moreover, RMS error by using non-linear GPA was less than that by using linear GPA.