• KSII Transactions on Internet and Information Systems (TIIS)
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• v.7 no.4
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• pp.910-922
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• 2013

In 2008, Chin et al. proposed an efficient and provable secure identity-based identification scheme in the standard model. However, we discovered a subtle flaw in the security proof which renders the proof of security useless. While no weakness has been found in the scheme itself, a scheme that is desired would be one with an accompanying proof of security. In this paper, we provide a fix to the scheme to overcome the problem without affecting the efficiency as well as a new proof of security. In particular, we show that only one extra pre-computable pairing operation should be added into the commitment phase of the identification protocol to fix the proof of security under the same hard problems.

• Proceedings of the KIEE Conference
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• 1994.07a
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• pp.379-381
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• 1994

This paper is concerned with a zero-voltage soft-switching PWM DC-DC high-pelter converter using IGBTs, which Bakes the most of the parastic LC parameters of high-voltage transformer link, for diagnostic X-Ray power generator. The converter circuit basically utilizes phase-shift pulse width modulated series resonant full-bridge PWM DC-DC high-Power converter operating at a constant frequency:20kHz. This technique brings about dramatic decreases in the switching losses of power devices and their electrical stresses as compared with the commonly-used hard-switching PWM DC-DC power converter. The high-frequency switching operation of the converters has some effective advantages, which consist in the physical reduction in size and weight and lowered acoustic noise.

• Journal of information and communication convergence engineering
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• v.9 no.5
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• pp.591-596
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• 2011

Image denoising is a key issue in all image processing researches. Generally, the quality of an image could be corrupted by a lot of noise due to the undesired conditions of image acquisition phase or during the transmission. Many approaches to image restoration are aimed at removing either Gaussian or impulse noise. Nevertheless, it is possible to find them operating on the same image, which is called mixed noise and it produces a hard damage. In this paper, we proposed noise type classification method and a mixed nonlinear filter for mixed noise suppression. The proposed filtering scheme applies a modified adaptive switching median filter to impulse noise suppression and an efficient nonlinear filer was carried out to remove Gaussian noise. The simulation results based on Matlab show that the proposed method can remove mixed Gaussian and impulse noise efficiently and it can preserve the integrity of edge and keep the detailed information.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.611_612
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• 2009

This paper deals with dynamic analysis of linear switched reluctance motor considering electromagnetic characteristics. First, inductance profile of linear switched reluctance motor calculate at align and unalign position and phase resistance using analytical method. Analytical method of this paper used space harmonics method, also, analysis result compares with data that is derived through an finite element method, and proved validity. In dynamic simulation of linear switched reluctance, we analyzed dynamic characteristic of linear switched reluctance motor according to single pulse waveform and hard chopping voltage PWM.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.16 no.3
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• pp.171-177
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• 2004

A new wave gauge using digital image of waves is developed and the performances are tested by wave tank experiments. This wave gauge uses frame frequency of 1/15 sec, conversion of analog images to digital images, and large capacity of hard disk. This wave gauge measures wave heights by detecting the buoy movement automatically from the image, where the buoy moves with the same phase of water surface. The comparison of automatic measurements of wave heights to the true data is reasonable. The wave gauge can be improved to measure wave heights on shallow waters near shorelines.

• Journal of Korean Institute of Industrial Engineers
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• v.27 no.4
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• pp.379-383
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• 2001

The restricted shortest path problem is known to be weakly NP-hard and solvable in pseudo-polynomial time. Four fully polynomial approximation schemes (FPAS) are available in the literature, and most of these are based on pseudo-polynomial algorithms. In this paper, we propose a new FPAS that can be easily derived from a combination of a set of standard techniques. Although the complexity of the suggested algorithm is not as good as the fastest one available in the literature, it is practical in the sense that it does not rely on the bound tightening phase based on approximate binary search as in Hassin's fastest algorithm. In addition, we provide a review of standard techniques of existing works as a useful reference.

• Journal of Powder Materials
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• v.16 no.3
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• pp.173-179
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• 2009

In the present study, Zr-base metallic glass(MG)/diamond composites are fabricated using a combination of gas-atomization and spark plasma sintering (SPS). The densification behaviors of mixtures of soft MG and hard diamond powders during consolidation process are investigated. The influence of mixture characteristics on the densification is discussed and several mechanism explaining the influence of diamond particles on consolidation behaviour are proposed. The experimental results show that consolidation is enhanced with increasing diamond/Metallic Glass(MG) size ratio, while the diamond fraction is fixed.

• Journal of Astronomy and Space Sciences
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• v.33 no.2
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• pp.69-73
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• 2016

We use the non-stationary three dimensional two-layer outer gap model to explain gamma-ray emissions from a pulsar magnetosphere. We found out that for some pulsars like the Geminga pulsar, it was hard to explain emissions above a level of around 1 GeV. We then developed the model into a non-stationary model. In this model we assigned a power-law distribution to one or more of the spectral parameters proposed in the previous model and calculated the weighted phase-averaged spectrum. Though this model is suitable for some pulsars, it still cannot explain the high energy emission of the Geminga pulsar. An Inverse-Compton Scattering component between the primary particles and the radio photons in the outer magnetosphere was introduced into the model, and this component produced a sufficient number of GeV photons in the spectrum of the Geminga pulsar.

• International Journal of Contents
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• v.5 no.2
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• pp.59-63
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• 2009

Since it is hard to use GPS for tracking mobile user in indoor environments, much research has focused on techniques using existing wireless local area network infrastructure. Signal strength received at a fixed location is not constant, so fingerprinting approach which use pattern matching is popular. But this approach has to pay additional costs to determine user location. This paper proposes a new approach to find user's location efficiently using an index scheme. After analyzing characteristics of RF signals, the paper suggests the data processing method how the signal strength values for each of the access points are recorded in a radio map. To reduce computational cost during the location determination phase, multidimensional indexes for radio map with the important information which is the order of the strongest access points are used.

• Korean Journal of Computational Design and Engineering
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• v.17 no.5
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• pp.342-352
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• 2012

As a futuristic construction model, building information model (BIM) based project management system (PMIS) and mobile BIM simulator apps have been showing visible sign. However, researches on the BIM based 3D simulator using mobile device are hard to find result from limitation of mobile device (slow speed at huge 3D file, display size, and etc.) and undefined standard of business processes. Therefore, this research aims at studying application of mobile BIM apps based on cloud computing. Total 8 BIM cloud apps were selected and analyzed in the 5 application feasibility characteristics (speed, view, inquiry, markup, and usability). This research would be essential phase to construct BIM based mobile project management system using cloud computing in the future.