• 한국전산유체공학회:학술대회논문집
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• 2005.04a
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• pp.173-181
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• 2005

A fluid transient analysis for the propellant flow in a monopropellant propulsion system is conducted using the method of characteristics (MOC). Algebraic simultaneous equations method and Clamor's rule method utilized to drive the compatible and characteristic equations are reviewed to understand MOC more extensively. The identification of fluid transient phenomena of propulsion system of Koreasat 1 is carried out through parametric studies. Also this work describes the reason that the propulsion system of Koreasat 1 has no orifice to control flow transients or to limit the initial hydrazine flow rate for the first-pulse firing.

• Proceedings of the KSME Conference
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• 2000.04b
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• pp.205-212
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• 2000

Induction motors. having axial cooling channels in stator and rotor are designed for better cooling performance. Traction motors are one of those examples. And, thermal analysis gain more attention with the Increased demand of the motors, for reliable operation and life prolongation. was Induced to effective thermal conductivity through modeling. Through. fundamental comparison experiment, heat source experiment and transient state experiment, the induction motor using inverter was examined to produce heat source with frequency level and traced to thermal variation at starting and stopping. And thermal analysis using thermal network was compared with a transient state experiment.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.54 no.10
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• pp.487-495
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• 2005

This paper reviews the characteristic of thermal and temperature of oil field cable in transient state such as grounding fault and lightning surge. For analysis in various conditions, many actual underground power cable systems are modeled using ATP. These results are applied for the examination of temperature increase when the single line to ground fault by the breakdown of insulation part and hitting of lightning surge are occurred. The inner part temperature of OF cable is analysed according to the various kinds of cable using the thermal model of transient state. The temperature increase of sheath and crossbonded lead bv fault current is also analysed using IEC 60949.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.05a
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• pp.830-835
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• 2002

Theoretical analysis about transient torsional vibration was started from early 1960's for high power synchronous motor application. Especially, its simulation and measuring techniques in marine engineering field have been steadily studied by classification societies and designers of large diesel engine. In this paper, the simulation method of transient torsional vibration of two stroke low speed diesel engine using the Newmark method are introduced.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.04a
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• pp.41-45
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• 2002

Transient magnetic diffusion process in a melt-cast BSCCO-2212 tube is analyzed by an analytical method. The transient diffusion equation is transformed into an ordinary differential equation by integral method. The penetration depth of magnetic field into a superconducting tube is obtained by solving the differential equation numerically. The results show that the penetration depth as a function of time which is somewhat different from the results by Bean's critical current model. The reason of the difference between the present results and that of Bean's model is discussed and compared in this paper.

• Transactions of the Korean Society of Mechanical Engineers
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• v.17 no.10
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• pp.2457-2466
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• 1993

A simple method is presented for determining transient responses of locally nonlinear structures using substructure eigenproperties and Lagrange multiplier technique. Although the method is based upon the mode synthesis formulation procedure, the equations of the combined whole structure are not constructed compared with the conventional methods. Lagrange multi-pliers are used to enforce the conditions of geometric compatibility between the substructure interfaces and they are treated as external forces on each substructure itself. Substructure eigenvalue problem is defined with the substructure interface free of fixed. The transient analysis is based upon the recurrence discrete-time state equations and offers the simplicity of the Euler integration method without requiring small time increment and iterative solution procedure. Numerical examples reveal that the method is very accurated and efficient in calculating transient responses compared with the direct numerical integration method.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.13 no.6
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• pp.514-523
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• 2001

The thermal performance characteristics of gas-loaded heat pipe(GLHP) were investigated by using transient diffuse-front model. Numerical evaluation of the GLHP is made with water as a working fluid and Nitrogen as control gas in the stainless steel tube. The transient vapor temperature and wall temperature were obtained. It is found that the temperature profiles and gas mole fraction distribution have been mainly influence by the diffusion between working fluid and noncondensable control gas in the condenser of GLHP. It is also found that he large power input make the diffusion region smaller.

• Journal of the Korea Society for Simulation
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• v.2 no.1
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• pp.91-106
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• 1993

Load sharing in distributed systems improves systems performance. Research in the field has been focused on steady state performance for load sharing algorithms. However, transient characteristics of such algorithms may be important in a distributed system in which workload for some node is changing. Simulation is the only means to analyze such characteristics. This paper presents a simulation-based analysis of the transient characteristics of four load sharing algorithms ; forward probing, reverse probing, symmetric probing, and multi-threshold symmetric probing algorithms. Discrete event system models for execution of the algorithms in a distributed system has been developed in a SIMSCRIOT II.5 environment. Simulation results indicate that the MSYM algorithm shows the shortest response time in the transient period.

• Journal of the Korean Institute of Telematics and Electronics
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• v.3 no.4
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• pp.16-24
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• 1966

The LASER Amplifier is treated in the manner of a Fabry-Perot Resonator with an active media, five layers are considered: air, reflector, active medium(ruby), reflector and air. One dimensional scalar wave equations are derived using the method of boundary value probrems in which it is assumed that incident coherent radiation falls normally on the surface wall. All equations are treated from the transient analysis point of view using the Laplace transform nethods, and are arranged steady state region as an amplifier and transient region as a self excited oscillator. Also some remarks are given on the design problem of LASER amplifier in connection with the transient terms involved.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.24 no.10
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• pp.21-25
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• 2010

This paper explains hybrid method that combines Time domain simulation technique with the direct method of Transient stability analysis. First, it calculate trajectory of real system by Time domain Simulation using OOP(Object Oriented Programming method) and evaluate Transient Energy Function to induce stability index to calculate Transient stability margin. Once the status of system(stable or unstable) has been identified, proper criteria are proposed to stop time-domain simulation to reduce CPU time.