• The Transactions of The Korean Institute of Electrical Engineers
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• v.65 no.1
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• pp.103-107
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• 2016

In general, the voltage stability of induction generator is lower than synchronous generator. Induction generator has a number of advantages over the synchronous generator on the side of price and maintenance. So Induction generator has been applied to the small hydroelectric power of low output. Induction generator usually generates a high current during grid connection. The high current that occurs during grid connection can cause a voltage drop in the system. In order to increase the supply of the induction generator, it is necessary to propose a method of reducing high current. This paper proposes some method of the soft start to reduce voltage drop caused by the large starting current. soft-start method has high voltage drop effect than direct start method, control of firing angle can be increased the voltage drop effect.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.12 no.10
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• pp.4774-4796
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• 2018

Wireless sensor networks are composed of a large number of inexpensive and tiny sensors used in different areas including military, industry, agriculture, space, and environment. Fault tolerance, which is considered a challenging task in these networks, is defined as the ability of the system to offer an appropriate level of functionality in the event of failures. The present study proposed an intelligent throughput descent and distributed energy-efficient mechanism in order to improve fault tolerance of the system against soft and permanent faults. This mechanism includes determining the intelligent neighborhood radius threshold, the intelligent neighborhood nodes number threshold, customizing the base paper algorithm for distributed systems, redefining the base paper scenarios for failure detection procedure to predict network behavior when running into soft and permanent faults, and some cases have been described for handling failure exception procedures. The experimental results from simulation indicate that the proposed mechanism was able to improve network throughput, fault detection accuracy, reliability, and network lifetime with respect to the base paper.

• Journal of Power Electronics
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• v.11 no.1
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• pp.10-15
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• 2011

In this paper, a new soft switching three phase inverter with a quasi-resonant dc-link is presented. The proposed inverter has a dc-link switch and an auxiliary switch. The inverter switches are turned on and off under zero voltage switching condition and all auxiliary circuit switches and diodes are also soft switched. The control utilizes PWM and the auxiliary switch does not require an isolated gate drive circuit. In this paper, the operation analysis and design considerations of the proposed soft switching inverter are discussed. The presented experimental results of a realized prototype confirm the theoretical analysis.

• Journal of the Korean Society of Industry Convergence
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• v.7 no.1
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• pp.83-89
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• 2004

The analysis about consolidation characteristic in soft clay has been depending one-dimension consolidation analysis. but, drain and undrain zone are explicated as homogeneous by consolidation behavior following consoli- dated settlementsoft in soft clay. 1) Established sand drain in soft clay in many types, and measured water content, unconfined compression strength, vertical stress, horizontal stress, vertical settlement, pore water pressure. 2) Arranged the result from the test and numerically explicated effective stress, total stress, and effective stress path at the drain and undrain zone. 3) We also analyzed and comparied elastic and elastic-plastic in soft clay using measured data. The result analyzed does not approach to a special theory, but, it is well in accord with the result of other investigator's study in the same condition.

• Journal of Magnetics
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• v.22 no.1
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• pp.29-33
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• 2017

We report a micromagnetic numerical study on different quasi-crystal formations of magnetic vortices in a rich variety of dynamic transient states in soft magnetic nano-disks. Only the application of spin-polarized dc currents to a single magnetic vortex leads to the formation of topological-soliton quasi-crystals composed of different configurations of skyrmions with positive and negative half-integer numbers (magnetic vortices and antivortices). Such topological object formations in soft magnets, not only in the absence of Dzyaloshinskii-Moriya interaction but also without magnetocrystalline anisotropy, are discussed in terms of two different topological charges, the winding number and the skyrmion number. This work offers an insight into the dynamic topological-spin-texture quasi-crystal formations in soft magnets.

• Journal of Electrical Engineering and Technology
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• v.13 no.4
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• pp.1539-1548
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• 2018

This paper introduces a new soft switched AC-DC boost converter with power factor correction (PFC). In the introduced converter, all devices are turned on and off under soft switching (SS). The main switch is turned on under zero voltage transition (ZVT) and turned off under zero current transition (ZCT). The main diode is turned on under zero voltage switching (ZVS) and turned off under zero current switching (ZCS). Meanwhile, there is not any current or voltage stress on the main devices. Besides, the auxiliary switch is turned on under ZCS and turned off under ZVS. The detailed theoretical analysis of the converter is presented, and also theoretical analysis is verified by a prototype with 100 kHz and 500 W. Also, the proposed converter has 99.8% power factor and 97.5% total efficiency at soft switching operation.

• Proceedings of the KIEE Conference
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• 1999.07g
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• pp.3199-3201
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• 1999

Convolutional coding with Viterbi decoding is known as a powerful method for forward error correction among many kinds of channel coding methods. This paper presents a soft decision Viterbi decoder which has systolic array trace-back architecture[1]. Soft decision is known as more effective method than hard decision and most of digital communication systems use soft decision. The advantage of using a systolic array decoder is that the trace-back operation can be accomplished continuously in an array of registers in a pipe-line fashion, instead of waiting for the entire trace-back procedure to be completed at each iteration. Therefore it may be suitable for faster communication system. We described operations of each module of the decoder and showed results of the logic synthesis and functional simulation.

• Journal of Power Electronics
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• v.18 no.1
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• pp.137-146
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• 2018

This paper describes a single pulse-width modulation control strategy using the Single Pulse-Width Modulation (SPWM) method with a soft-switching technique for a wide range of output voltages from a bidirectional Dual-Active Bridge (DAB) converter. This method selects two typical inductor current waveforms for soft-switching, and proposes a rule that makes it possible to achieve soft-switching without any compensation algorithm from the waveforms. In addition, both the step-up and step-down conditions are analyzed. This paper verifies that the leakage inductance is independent from the rule, which makes it easier to apply in DAB converters. An integrated algorithm, which includes step-up and step-down techniques, is proposed. The results of experiments conducted on a 50-kW prototype are presented. The system efficiency is experimentally verified to be from 85.6% to 97.5% over the entire range.

• Journal of the Korean Society of Safety
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• v.32 no.1
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• pp.108-114
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• 2017

According to an increase in demand for polyurethane soft foam for thermally insulated containers, the purpose of this study is based on redefining existing rigid polyurethane foam insulation KS standard which has been limited to building material-based authentication techniques. Since there are arising concerns of consumer rights and safety due to humidifier fungicides and urethane track incidents, there are elements to be further researched on rigid polyurethane foam insulation for refregerated containers. Thus, we reviewed the prior standards for rigid polyurethane foam insulation and verified the validity of certification testing method for the new standard with self-foamed polyurethane.

• The Journal of Engineering Geology
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• v.29 no.4
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• pp.427-437
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• 2019

The purpose of this study is to improve construction cost, time, and field management when constructing a road on soft soil foundation by eliminating extra-banking of subgrade layer after completion of the consolidation process. The subgrade layer was pre-constructed before the soft ground improvement. And then it was confirmed by the field test that the compaction effect was maintained or not after consolidation settlement. As a result of the experiment, all subgrade layers were kept constant except for the top subgrade layer. So it would be advantageous to secure economical and practical in road construction if subgrade layers were constructed exclusive of the top subgrade layer.