• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2000년도 춘계학술대회논문집
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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.

• Tribology and Lubricants
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• 제18권1호
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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.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2002년도 proceedings of the second asia international conference on tribology
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• pp.411-412
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• 2002

Piston-cylinder system are widely used in power engineering applications. In reciprocating refrigeration compressors, where extremely low friction losses are required, ringless pistons are being used to diminish the friction between piston rings and cylinder wall. Since the ringless piston has the freedom of lateral motion there is a potential danger that it will occasionally hit the cylinder wall while moving up and down along it's axis. A good design must therefore provide a smooth and stable reciprocating motion of the piston and ensure that the fluid film separating the piston from the cylinder wall is maintained all times. And the compromise between refrigerant gas leakage through the piston-cylinder clearance and the friction losses is required utilizing a dynamic analysis of the secondary motion for the high efficiency compressor. To this end, the computer program is developed for calculating the entire piston trajectory and the lubrication characteristics as functions of crank angle under compressor running conditions. The results explored the effects of some design parameters and operating conditions on the stability of the piston, the oil leakage, and friction losses.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 추계학술대회 논문집 학회본부 C
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• pp.898-900
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• 1998

This paper describes the motion characteristics and micro-discharge of the free conducting particles between plain electrodes under alternating voltage. The particles move between both electrodes due to electrostatic force by applied AC voltage. Various types and sizes of free conducting particles were used to study the motion and micro-discharge characteristics. The micro-discharge and breakdown were observed during the particle motion.

• 한국자동차공학회논문집
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• 제5권2호
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• pp.197-204
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• 1997

In order to investigate the relationship between the ring gap ratio and oil consumption, the axial motion of piston ring was measured by capacitance technique. The pressures of each land and the motions of each ring were calculated by orifice-volume method in which it is assumed that the ring gaps are the only gas leakage paths. The calculated results were compared with the measured ones. Consequently, it is known that the increase of ring gap ratio has the effect of lifting the first ring. The calculated results were roughly in accordance with those measured. Therefore, it is possible to predict the effect of design variables on the pattern of ring motion. It is known that the lift off of first ring accompanied by the increase of ring gap ratio make rise of oil consumption.

• 소성∙가공
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• 제26권5호
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• pp.277-285
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• 2017

Vehicle weight reduction is a known strategy to improve fuel efficiency and strengthen exhaust gas regulation. The use of high strength steel can satisfy safety, efficiency, emission, manufacturability, durability, and cost requirements. However, springback of high strength steel results in undesired shape defects. Springback is one of the most important issues of high strength steel for many applications in an automobile. Servo press has various capabilities to improve defects, process conditions, and productivity problems when forming a high strength steel. Especially, servo press can be set to function with variable slide motion in a single operation. In this study, the effect of servo press slide motion on 980MPa high strength steel was investigated through U-bending test.

• 한국해양공학회지
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• 제25권5호
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• pp.64-68
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• 2011

The motion responses of a 5-MW floating offshore wind turbine were simulated in regular and irregular waves and its RAOs and significant motion responses were calculated, respectively. The floating offshore wind turbine employed in this simulation was the OC3-Hywind designed by the National Renewable Research Laboratory, USA. The numerical simulation was carried out using MOSES (Multi-Operational Structural Engineering Simulator), which is widely used to analyze and design floating offshore structures in the gas and oil industry.

• Ocean Systems Engineering
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• 제12권2호
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• pp.173-223
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• 2022

In oil and gas industry, FPSO concept is the most popular hull form and ship shaped hull form dominants the FPSO market. Only a non-ship-shaped hull in operations with minor market shares is the cylindrical FPSO hull with medium to small storage capability. To add contracting options and competitions to reduce field development costs, an innovative turretless low motion hull, eco-FPSO, with 1MM bbls oil storage capacity and suitable for installing topsides modulars and equipping with regular SCRs, was first introduced in Zou (2020a). Dynamic characteristic responses of the eco-FPSO compared to the traditional SS-FPSO hull and DD-Semi platform are presented and discussed in this paper, suitability and feasibility of the proposed hull have been demonstrated and validated through extensive analyses in 10-yrp, 100-yrp and 1,000-yrp hurricanes in ultra-deepwater central GoM.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 추계학술대회 논문집 학회본부 C
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• pp.525-527
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• 2000

Ultra high frequency (UHF) signals caused by the bouncing motion of aluminium particles in the 352 kV gas-insulated switchgear (GIS) test chamber were measured in order to investigate the signal pattern against the applied voltage phase and ultra sonic signals.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2007년도 동계학술발표대회 논문집
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• pp.404-409
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• 2007

For a hermetic reciprocating compressor, it has been known that the gas pulsation in the suction line affects the compressor performance, and suction muffler design has been focused on both of noise reduction and minimum pressure drop across the muffler. Some studies have been carried out on the mutual interaction between the gas pulsation and the cylinder pressure to investigate some supercharging effects, but their efforts were limited on rather simple geometries. In this paper, interaction of the gas pulsation in the compressor suction line with cylinder pressure via suction valve motion has been calculated; for the gas pulsation analysis, modeling of Helmholtz resonators in series was used, and for cylinder pressure calculation, energy equations was set up for the gas inside the cylinder. For demonstration of this calculation method, four different types of suction line configurations for a hermetic reciprocating compressor were compared in terms of compressor performance and gas pulsation level.