• Journal of IKEEE
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• v.22 no.1
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• pp.61-67
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• 2018

We investigated theoretically the magnetic field dependence of the quantum optical transition of qusi 2-Dimensional Landau splitting system, in CdS and ZnO. In this study, we investigate electron confinement by square well confinement potential in magnetic field system using quantum transport theory(QTR). In this study, theoretical formulas for numerical analysis are derived using Liouville equation method and Equilibrium Average Projection Scheme (EAPS). In this study, the absorption power, P (B), and the Quantum Transition Line Widths (QTLWS) of the magnetic field in CdS and ZnO can be deduced from the numerical analysis of the theoretical equations, and the optical quantum transition line shape (QTLS) is found to increase. We also found that QTLW, ${\gamma}(B)_{total}$ of CdS < ${\gamma}(B)_{total}$ of ZnO in the magnetic field region B<25 Tesla.

• Journal of the Korean Institute of Telematics and Electronics
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• v.24 no.1
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• pp.133-139
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• 1987

A phase-locked Channel-Substrate-Planar(CSP) laser arrays is described. Arrays of emitters with weak coupling are operated in a set of discrete modes determined by the number and spacing of the emitters. The interactions between emitters lead to a splitting of the wave-length and gain which are calculated from the coupling strength. Phase-locked arrays has exhibited to CW output-power as high as 80 m W and the highest order mode will have preferred oscillation. A strong hole burning is occurred at p=30m W. The most stable lasing mode is occurred at element spacing S=3.5\ulcornerm and there is no coupling at S>7 \ulcornerm.

• Proceedings of the Optical Society of Korea Conference
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• 2000.02a
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• pp.124-125
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• 2000

We introduce a scheme with a maximized efficiency of detecting atoms passing through an optical standing-wave mode cavity. Consider a standing-wave optical cavity illuminated by a weak probe beam through one of its mirrors where the transmission through the other mirror is monitored by a photodetector. If an atom is put in the cavity, the atom-cavity coupling shifts the resonance frequency of the system via the so-called normal mode splitting, and thereby the transmission power will drop. In fact, this type of atom detection scheme has been used in recent single atom trap experiments In practice, however, the field in a standing-wave mode will have a geometrical structure having nodes and antinodes that when the atom traverses the cavity through one of the nodes, there will be no such effect of atom-field interaction. (omitted)

• Transactions of the Korean Society of Mechanical Engineers A
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• v.32 no.6
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• pp.496-503
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• 2008

With the improvement of computer power and technology, fracture modelling by finite element methods has become a topic of extensive studies. However, fracture simulation much limited to an academic study of crack propagation with a fine mesh. Element deletion method is a useful tool for estimating damage due to accidental or extreme loads on structures, provided that an effective and realistic criterion is established for simulating the material failure and subsequent element deletion. In this study, ABAQUS/Explicit is used to simulate the material failure on the basis of experimental results by X. Huang et al. Through numerical experiments, we suggest a formulation to determine the failure strain associated with the size and thickness of removed elements.

• Journal of Magnetics
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• v.16 no.4
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• pp.408-412
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• 2011

We investigated theoretically the magnetic field dependence of the quantum optical transition of qusi 2-Dimensional Landau splitting system, in GaN and ZnO. We apply the Quantum Transport theory (QTR) to the system in the confinement of electrons by square well confinement potential. We use the projected Liouville equation method with Equilibrium Average Projection Scheme (EAPS). Through the analysis of this work, we found the increasing properties of the optical Quantum Transition Line Shapes(QTLSs) which show the absorption power and the Quantum Transition Line Widths(QTLWs) with the magnetic-field in GaN and ZnO. We also found that QTLW, ${\gamma}(B)_{total}$ of GaN < ${\gamma}(B)_{total}$ of ZnO in the magnetic field region B < 25 Tesla.

• ETRI Journal
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• v.40 no.1
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• pp.61-71
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• 2018

In this study, we developed hybrid control algorithms in smart base stations (SBSs) along with devised communication, caching, and computing techniques. In the proposed scheme, SBSs are equipped with computing power and data storage to collectively offload the computation from mobile user equipment and to cache the data from clouds. To combine in a refined manner the communication, caching, and computing algorithms, game theory is adopted to characterize competitive and cooperative interactions. The main contribution of our proposed scheme is to illuminate the ultimate synergy behind a fully integrated approach, while providing excellent adaptability and flexibility to satisfy the different performance requirements. Simulation results demonstrate that the proposed approach can outperform existing schemes by approximately 5% to 15% in terms of bandwidth utilization, access delay, and system throughput.

• Applied Science and Convergence Technology
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• v.27 no.5
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• pp.105-108
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• 2018

Transparent $TiO_2$ nanotube arrays are successfully prepared by a two-step approach involving electrochemical anodization and RF magnetron sputtering. First, a Ti film is deposited on an FTO substrate by RF magnetron sputtering at room temperature. The morphologies of the Ti film are controlled by the working distance, Ar flow, and DC power. Second, an anodization treatment is electrochemically performed for the formation of nanotube arrays from the deposited Ti film, followed by post-annealing treatment in air for the formation of $TiO_2$ crystallization. The back side of the crystallized $TiO_2$ nanotube arrays is illuminated with solar light to characterize the photoelectrochemical reaction, and their photoelectrochemical properties are investigated. This work provides information on application of a thin film deposited by RF sputtering in the field of photoelectrochemical water splitting.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.26 no.2
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• pp.335-344
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• 2016

It is known that power analysis is one of the most powerful attack in side channel analysis. Among power analysis single trace attack is widely studied recently since it uses one power consumption trace to recover secret key of public cryptosystem. Recently Sim et al. proposed new exponentiation algorithm for RSA cryptosystem with higher attack complexity to prevent single trace attack. In this paper we analyze the vulnerability of exponentiation algorithm described by Sim et al. Sim et al. applied message blinding and random exponentiation splitting method on $2^t-ary$ for higher attack complexity. However we can reveal private key using information exposed during pre-computation generation. Also we describe modified algorithm that provides higher attack complexity on collision attack. Proposed algorithm minimized the reuse of value that are used during exponentiation to provide security under single collision attack.

• Journal of Communications and Networks
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• v.13 no.6
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• pp.664-677
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• 2011

In order to control interference and improve spectrum efficiency in the femtocell and macrocell overlaid system (FMOS), we propose a joint frequency bandwidth dynamic division, clustering and power control algorithm (JFCPA) for orthogonal-frequency-division-multiple access-based downlink FMOS. The overall system bandwidth is divided into three bands, and the macro-cellular coverage is divided into two areas according to the intensity of the interference from the macro base station to the femtocells, which are dynamically determined by using the JFCPA. A cluster is taken as the unit for frequency reuse among femtocells. We map the problem of clustering to the MAX k-CUT problem with the aim of eliminating the inter-femtocell collision interference, which is solved by a graph-based heuristic algorithm. Frequency bandwidth sharing or splitting between the femtocell tier and the macrocell tier is determined by a step-migration-algorithm-based power control. Simulations conducted to demonstrate the effectiveness of our proposed algorithm showed the frequency-reuse probability of the FMOS reuse band above 97.6% and at least 70% of the frequency bandwidth available for the macrocell tier, which means that the co-tier and the cross-tier interference were effectively controlled. Thus, high spectrum efficiency was achieved. The simulation results also clarified that the planning of frequency resource allocation in FMOS should take into account both the spatial density of femtocells and the interference suffered by them. Statistical results from our simulations also provide guidelines for actual FMOS planning.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.19 no.5
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• pp.55-62
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• 2019

In this paper, we consider K-user multiple-input multiple-output (MIMO) interference channel and present a transceiver design for simultaneous wireless information and power transfer (SWIPT) systems. In addition, we consider a SWIPT system where an information decoding receiver and an energy harvesting receiver are co-located at the same receiver. In the proposed scheme, signal-to-leakage plus noise ratio (SLNR) is used as a cost function and a transceiver is designed to satisfy the threshold of the harvested energy. More specifically, transmitter precoding vector, receiver filter vector, and power spitting factor are simultaneously designed to maximize SLNR with a constraint on the harvested energy. Through computer simulation, we compare the signal-to-interference plus noise ratio (SINR) performance of the proposed and conventional schemes. When a special condition among the number of transmit antennas, receive antennas, and users is satisfied, the proposed scheme showed better SINR performance than the conventional scheme at low signal-to-noise ratio (SNR) range. Also, when the condition is not satisfied, the proposed scheme showed better performance than the conventional scheme at all SNR range.