• Journal of the Korean Institute of Intelligent Systems
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• v.12 no.4
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• pp.311-316
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• 2002

Difficulties of the level control in the steam generator are increased due to their nonlinear characteristics. Futhermore, parameter uncertainties of the steam generator is related with control performance and stability. The efficiency of digital conversion in control systems is proved in many recent researches. In order to solve this problem, this paper suggests robust digital fuzzy controller design methodologies of the steam generator which have unstable parameters. Takagi-Sugeno (TS) fuzzy model is used to construct a fuzzy model which has uncertainties in the steam generator. In designing procedure, intelligent digital redesign method is used to control the nonlinear system. This digital controller keeps the performance of the analog controller. Simulation examples are included for ensuring the proposed control method.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.38 no.6
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• pp.663-668
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• 2014

Mechanical and electrical devices in various forms are used in many different fields. These can be exposed to external environmental factors such as shock. Therefore, a shock test machine is commonly used to test these devices and evaluate their shock resistance. In this test, the break-down or permanent deformation and malfunction of inner parts due to a high stress or acceleration can be evaluated. As part of a shock test machine, a velocity generator is needed to create shocks between objects. In this study, a hydraulic velocity generator was conceptually designed and an AMESim model was developed to simulate the velocity under different conditions. Simulation results using this model were compared with the test results from a reduced-size velocity generator, and we designed a velocity generator that fits the target payload and velocity using the simulation results.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.9
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• pp.5452-5459
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• 2014

A resonance linear electric generator in a vehicle suspension is a system that performs self-electric generation by collecting the vibration energy when a vehicle runs on a road, and takes the resonance phenomenon to derive large electric generation from slight road surface vibrations. In this paper, the motions of an armature in three different electric generator structures were simulated and the actual generation quantity was calculated and compared with these results. Furthermore, when the vehicle runs on the road, the design improvement for a multi-degree of freedom electric generator was conducted to make the resonance respond to various excitation frequencies, and the change in the resonance points and generation quantity were identified.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.6
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• pp.3357-3362
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• 2014

The purpose of this research was to develop a resonance electric power generator to harvest vibration energy while the vehicle is driving on a road surface. The electric power generator in the paper was designed using the resonance phenomenon to effectively respond to vibrations from the road surface, which is a comparatively small energy source. Vibration displacement analysis using MATLAB and transient analysis using Ansys MAXWELL, which is a commercial electromagnetic analysis program, was performed to predict the input velocity for the generator and verify the electric power generation. If this electric power generator is applicable to hybrid or electric vehicles, it can be valuable around an automotive electric system and help maintain the performance of the vehicle battery.

• Journal of the Institute of Electronics and Information Engineers
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• v.53 no.12
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• pp.42-49
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• 2016

This paper proposes a low-complexity generator which finds the first two minimum values using bit-serial scheme. A low-complexity generator is an important part for low-area LDPC decoders based on the min-sum decoding algorithm because the hardware complexity of generators utilizes a significant portion of LDPC decoders. To reduce hardware complexity, bit-serial LDPC decoders has been studied. The generator of the existing bit-serial LDPC decoders can find only the first minimum value, and thus it leads to a BER performance degradation. The proposed generator using bit-serial scheme finds the first two minimum values. Hence, it can improve the BER performance. In addition, the area-time complexity of the proposed generator is lower than those of the existing generators finding the first two minima.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.33 no.2
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• pp.130-134
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• 2020

Metal oxide varistors (MOVs) protect circuits and devices from transient overvoltages in electric power systems. However, a MOV continuously deteriorates owing to manufacturing defects or repetitive protective operations from transient overvoltages. A deteriorated MOV may result in a short circuit or a line-ground accident. Previous studies focused on the analysis of deterioration mechanisms and condition diagnosis techniques for MOVs owing to their recent growth of use. An accelerated deterioration experiment under the same conditions in which a MOV operates is essential. In this study, we designed and fabricated a surge generator that can apply a surge current to a MOV connected to AC mains. The coupling network operates at a low impedance against the surge current from the surge generator and transfers the surge current to the MOV under test. It also acts as a high impedance against AC mains for the AC voltage not to be applied to the surge generator. The decoupling network operates at a high impedance against the surge current and blocks the surge current from AC mains. It also acts as a low impedance against AC mains for the AC voltage to be applied to the MOV under test. The prototype surge generator can apply the 8/20 us up to 15 kA on AC voltages in the approximate range of 110~450 V, and it fully operates on a LabVIEW-based program.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.34 no.9
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• pp.1217-1225
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• 2010

The possibility of a sodium-water reaction occurring in a conventional single-wall-tube steam generator in an SFR is a major problem. To improve the reliability of a steam generator, a double-wall-tube steam generator that can reduce the possibility of the occurrence of a sodium-water reaction is being developed. Current developments are focusing on improving the heat-transfer capability of a double-wall tube; further, the development of a leak-detection method to detect the occurrence of a sodium-water reaction during the reactor operation is also underway. In this study, new concepts, which will solve the above-mentioned problems, have been developed. Accordingly, a double-wall tube has been designed, fabricated, and mechanically tested for the purpose.

• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.8 no.2
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• pp.14-20
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• 2012

Full load rejection capability of nuclear power plant depends primarily on steam dump capacity (SDCAP) and steam generator level control capability. Recently, Ulchin Units 1&2 have performed stretched power uprate (SPU) and replacement steam generator (RSG) projects, which increase the power by 4.5 percent. They change major design or operating parameters and especially reduces steam dump capacity at full power due to increase of the steam flow. The reduction of SDC after SPU results in degradation of heat removal capability in full load rejection transients. Therefore, we should perform evaluation to determine whether reactor trips occur in large load rejection transients. Uchin Units 1&2 have experienced full load rejection (FLR) three times from 2004 to 2010. Operating data from the plant occurrence of FLR at Ulchin Units 1&2 showed that steam generator (SG) level transients were limiting in point of reactor trip. However the plant had never reached reactor trip in the FLR and successfully continued in house load operation. The parameters and setpoints for the SG will be changed if the SG is replaced. Therefore, we evaluated the appropriateness of steam dump, main feedwater and steam generator water level control system preventing the plant from reactor trip in case of FLR by the parameter sensitivity study whether SG water level operated smoothly after SPU and RSG projects.

• Journal of Korea Society of Industrial Information Systems
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• v.7 no.2
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• pp.74-81
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• 2002

In general, a multipath generator consists of a time delay generator, phase rotator, and amplitude attenuator, and is implemented mostly in an analog manner. Analog, or partially analog versions of a multipath generator is disadvantageous in that they may suffer from problems associated with component aging and adjustment, signal fidelity degradation stemming from repeated A/D and D/A conversion use of high frequency to achieve fine i.e., subsample fractional tin delays. This paper presents the design and implementation methodology of a full digital multipath generator which can be used in performance evaluations of digital terrestrial television as well as communications, receivers. In particular, an efficient practical method is proposed which can achieve both integer and fractional time delays simultaneously, without placing restrictions on the allowable system master clock frequency. The proposed algorithm lends itself to minimizing hardware implementation cost by relegating some fixed put of the computation involved to an IBM PC. The proposed multipath generator occupies only a single digital board space, and its experimental results are provided to corroborate the proposed implementation methodology.

• Journal of Power System Engineering
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• v.22 no.1
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• pp.41-47
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• 2018

This paper analyzes the output characteristics of a self excited induction generator with isolated mode according to change of its speeds and loads for building a hybrid electric propulsion system in special purpose ships by using power take off. The induction generators are being considered as an alternative choice to the well-developed generators because of their lower unit cost, inherent ruggedness, operational and maintenance simplicity. However, the generator working by stand alone has a few problems that the reactive power is required to establish the air gap magnetic flux, and the induced voltage and magnetizing current fluctuate when the load is varied. In spite of its advantages, basic design data of the capacitor bank and behaviors of the output characteristics of the generator are not sufficient for the system. Based on the operating condition(speed range of main engine) of the target boat, a reduced experimental equipment system was constructed to analyze the output characteristics of the SEIG. And a suitable capacitor bank of a stand-alone generator and its output characteristics under various loads was investigated in detail through these experiments. According to the experimental result, it was confirmed that the capacitor bank should be $70{\mu}F{\sim}100{\mu}F$, and the proper SEIG induced voltage should be DC 80 V ~ 250 V in order to storage electrical energy into a battery.