• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2003.05a
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• pp.258-261
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• 2003

The optimal design and combustion analysis of the gas generator for Liquid Rocket Engine (LRE) were performed. A fuel-rich gas generator in open cycle turbopump system was designed for 101on1 in thrust with RP-1/LOx combination. The optimal design was done for maximizing specific impulse of main combustion chamber with constraints of combustion temperature and power matching in turbopump system. Results of optimal design show the dimension of length, diameter, and contraction ratio of gas generator. The configuration of the gas generator and the condition for performance which can maximize the objective function were determined and found to meet the design constraints. Also, the combustion analysis was conducted to evaluate the performance of designed chamber and injector of gas generator. And the effect of the turbulence ring was investigated on the mixing enhancement in the chamber.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.32 no.5
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• pp.91-96
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• 2004

An optimal design of the gas generator for Liquid Rocket Engine (LRE) was conducted. A fuel-rich gas generator in open cycle turbopump system was designed for 10ton in thrust with RP-1/LOx propellant. The optimal design was done for maximizing specific impulse of thrust chamber with constraints of combustion temperature and for matching the power requirement of turbopump system. Design variables are total mass flow rate to gas generator, O/F ratio in gas generator, turbine injection angle, partial admission ratio, and turbine rotational speed. Results of optimal design provide length, diameter, and contraction ratio of gas generator. And the operational condition predicted by design code with resulting configuration was found to maximize the objective function and to meet the design constraints. The results of optimal design will be tested and verified with combustion experiments.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.15 no.6
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• pp.257-266
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• 2015

There is no polynomial-time algorithm that can be obtain the optimal solution for economic load dispatch problem with non-convex fuel cost functions. Therefore, electrical field uses quadratic fuel cost function unavoidably. This paper proposes a valve-point optimization (VPO) algorithm for economic load dispatch problem with non-convex fuel cost functions. This algorithm sets the initial values to maximum powers $P_i{\leftarrow}P_i^{max}$ for each generator. It then reduces the generation power of generator i with an average power cost of $_{max}\bar{c}_i$ to a valve point power $P_{ik}$. The proposed algorithm has been found to perform better than the extant heuristic methods when applied to 13 and 40-generator benchmark data. This paper consequently proves that the optimal solution to economic load dispatch problem with non-convex fuel cost functions converges to the valve-point power of each generator.

• Journal of the Korean Society for Precision Engineering
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• v.19 no.4
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• pp.168-178
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• 2002

The CNC machine toots has two kinds of fault. One is the fault due to degraded parts and the other is the fault due to operation disability. The phenomena of degradation is predictable but the operational fault is unpredictable because it occurred without any warning. The major faults of CNC machine tool are operational faults which are charged over 70%. This paper describes the model of remote service and the intelligent fault diagnosis system to diagnosis operational faults of CNC machine tools. To generalize fault diagnosis, two diagnosis models such as SF(Switching Function) and SSF(Step Switching Function) are proposed. The SF is static model and SSF is dynamic model for expression of fault. The SF and SSF model can be generated using SFG(Switching Function Generator) which is developed in this research. The three major operational faults such as emergency stop error, cycle start disability and machine ready disability are applied to experiment of fault modeling. To remote service of faults fur CNC machine tool, the web server and client system based internet are proposed as the suitable environment. The developed two technologies are implemented with the internal function of open architecture controller. The implemental results for two technologies are presented to validate the proposed scheme.

• Journal of Electrical Engineering and Technology
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• v.12 no.1
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• pp.145-150
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• 2017

This paper present a unified method of steady state performance analysis and limits characteristics of an autonomous three-phase self-excited induction generator (SEIG) driven by a wind turbine under different types of loads and speeds. The proposed method is based on a new mathematical function to solve for the real and imaginary components of the complex equation of the mathematical model. Performances limits, regulation and characteristics of different configurations will be thoroughly examined and compared. The proposed system will be modeled and simulated and the performance limits characteristics will be compared with variable speed and variable capacity.

• Transactions of the Korean Society of Automotive Engineers
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• v.21 no.4
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• pp.120-127
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• 2013

Hybrid electric vehicles have applied electric parts for saving fuel consumption and reducing levels of environmental pollution. Electrification of automobiles is indispensable for entering into global market because of enhanced environment restriction. ISG (Integrated Starter & Generator) system is one of main electric parts and can improve fuel efficiency more than other components by using Idle Stop & Go function and regenerative braking system. However, if ISG motor and inverter work under the continuously high load condition, it will make them the decrease of performance and durability. So the ISG motor and inverter need to properly design the cooling system of them. In this study, we suggested the enhancement points by modifying the thermal design of ISG motor and then confirmed the improvement of the cooling performance.

• Journal of Korea Society of Industrial Information Systems
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• v.7 no.5
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• pp.67-72
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• 2002

The number of keystream cycle sequences has been proposed as a characteristic of binary sequence generators for cryptographic applications, but in general most binary sequence generators have the only one-cycle sequence. In this paper, we propose a switching-tap LFSR as a basic function of a multiple-cycle binary sequence generator and the improved Rueppel's multiple-cycle generator. Finally we analyze its period, linear complexity, and the number of its keystream cycle sequences.

• Proceedings of the Korean Nuclear Society Conference
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• 1996.11a
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• pp.85-90
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• 1996

In this paper, the self-organizing fuzzy logic controller is developed for water level control of steam generator. In comparison with conventional fuzzy logic controllers, this controller performs control task with no control rules at initial and creates control rules as control behavior goes on, and also modifies its control structure when uncertain disturbance is suspected. Selected parameters in the fuzzy logic controller are updated on-line by the gradient descent loaming algorithm based on the performance cost function. This control algorithm is applied to water level control of steam generator model developed by Lee, et al. The computer simulation results confirm good performance of this control algorithm in all power ranges. This control algorithm can be expected to be used for automatic control of feedwater control system in the nuclear power plant with digital instrumentation and control systems.

• Journal of the Korean Institute of Telematics and Electronics
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• v.26 no.10
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• pp.1606-1616
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• 1989

In this paper, the design of DYNAMIC CMOS ARRAY LOGIC which has both advantages of dynamic CMOS and array logic circuits is proposed. The major components of DYNAMIC CMOS ARRAY LOGIC are two-stage dunamic CMOS circuits and an internal clock generator. The function block of dynamic CMOS circuits is realized as a parallel interconnection of NMOS transistors. Therefore the operating speed of DYNAMIC CMOS ARRAY LOGIC is much faster than the one of the conventional dynamic CMOS PLAs and static CMOS PLA. Also, the charge redistribution problem by internl delay is solved. The internal clock generator generates four internal clocks that drive all the dynamic CMOS circuits. During evaluation, two clocks of them are delayed as compared with others. Therefore the race problem is completoly eliminated. The internal clock generator also prevents the reduction of circuit output voltage and noise margin due to leakage current and charge coupling without any penalty in circuit operating speed or chip area utilization.

• Proceedings of the KIEE Conference
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• 1989.07a
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• pp.28-30
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• 1989

This paper is analyzed the electrical characteristics of the round solid rotor of turbo-generator without damper cage influence the induction generation modes and the torsional interaction modes of the SSR phenomena, and then examines the problem of representing electrical characteristics which is dependent on frequency and different wedge materials. The basic model of turbo-generator used in the field analysis is viewed as 5-regions of different permeability and conductivity characteristics. The analytical method, which is used in this paper is based on solving a boundary value problem involving 3-D fields, and the basic function consists of the 2-D Fourier series.