• KSII Transactions on Internet and Information Systems (TIIS)
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• v.14 no.7
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• pp.2815-2839
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• 2020

In a cloud computing paradigm, allocation of various virtualized ICT resources is a complex problem due to the presence of heterogeneous application (MapReduce, content delivery and networks web applications) workloads having contentious allocation requirements in terms of ICT resource capacities (resource utilization, execution time, response time, etc.). This task of resource allocation becomes more challenging due to finite available resources and increasing consumer demands. Therefore, many unique models and techniques have been proposed to allocate resources efficiently. However, there is no published research available in this domain that clearly address this research problem and provides research taxonomy for classification of resource allocation techniques including strategic, target resources, optimization, scheduling and power. Hence, the main aim of this paper is to identify open challenges faced by the cloud service provider related to allocation of resource such as servers, storage and networks in cloud computing. More than 70 articles, between year 2007 and 2020, related to resource allocation in cloud computing have been shortlisted through a structured mechanism and are reviewed under clearly defined objectives. Lastly, the evolution of research in resource allocation techniques has also been discussed along with salient future directions in this area.

• Information and Communications Magazine
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• v.19 no.11
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• pp.24-31
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• 2002

지금까지 SDR을 비판적인 시각으로 검토해 보았다 하지만 분명한 것은 SDR은 disruptive technology의 기능성을 가지고 있다는 점이다. 현재 domain specific하게 vertical market을 구축하고 있는 구현방식을 horizontal market으로 바꿔보자는 발상으로 전체적인 기술과 시장의 대세와 일치하기 때문이다. 저자의 관점은 SDR을 technology-driven 한발상으로 '일단 SDR이다' 라고 revolution으로 접근하는 것은 옳지 않다고 보는 것이다. SDR이란 Hype이 Real이 되려면 (1) power 소모, co-working과 같은 기술적인 문제들이 해결되고, (2) SDR 도입을 지연시키는 시장 환경이 개선되어야 하며, (3) software download, middleware 나 operating system과 관련된 정치적인 문제들이 해결되어야 한다. 이러한 문제들은 하루 아침에 해결되는 것이 아니기 때문에 market-driven한 관점에서 SDR concept이 기존의 장벽들을 극복할 수 있을 때 하나씩 SDR cencept을 채용해가는 evolution으로 접근하는 것이 중요하다. 앞으로도 Moore의 법칙은 15년에서 20년 가까이 지속될 것으로 전망하고 있다. 이미 Moore의 법칙에 의한 기술발전이 수요를 앞서는 조짐이 나타나고 있는 분야도 있어 남아도는 gate를 어떻게 활용할 것인가에 대해 회사마다 다른 전략을 펴고 있다. 특히 TI가 DSP 기반으로 벌인 다양한 사업전력, Intel이 CPU 기반으로 벌이는 Radio Free 사업 전략은 SDR에 대해 많은 시사점을 던져 준다. MMITS Forum에서 시작하여 SDR Forum 초창기, 현재의 SDR Forum 까지 SDR의 개념은 시장의 반응에 따라 변해 왔고, 일부 기술들은 더 이상 SDR 이라는 그늘에 머물지 않고 독자적인 기술군을 형성해 가고 있다. 분명한 것은 SDR 기술은 시장에서의 도전을 바탕으로 끊임없이 변해왔고 앞으로도 변해 갈 것이다. 지금의 비전이 최종적인 것이라고 섣불리 판단하고, 시장의 기술 흐름을 아전인수식으로 해석하고 만병통치 약을 만들려는 시도는 실패 잉태하고 있는 매우 위험한 발상이다. SDR이 꿈꾸는 세상은 이상향임에 틀림없지만 항상 시장을 주도하는 것은 꿈이 아니라 가격 경쟁력이기 때문이다.

• Smart Structures and Systems
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• v.5 no.4
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• pp.483-494
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• 2009

Damage detection has been proven to be a challenging task in structural health monitoring (SHM) due to the fact that damage cannot be measured. The difficulty associated with damage detection is related to electing a feature that is sensitive to damage occurrence and evolution. This difficulty increases as the damage size decreases limiting the ability to detect damage occurrence at the micron and submicron length scale. Damage detection at this length scale is of interest for sensitive structures such as aircrafts and nuclear facilities. In this paper a new photonic sensor based on photonic crystal (PhC) technology that can be synthesized at the nanoscale is introduced. PhCs are synthetic materials that are capable of controlling light propagation by creating a photonic bandgap where light is forbidden to propagate. The interesting feature of PhC is that its photonic signature is strongly tied to its microstructure periodicity. This study demonstrates that when a PhC sensor adhered to polymer substrate experiences micron or submicron damage, it will experience changes in its microstructural periodicity thereby creating a photonic signature that can be related to damage severity. This concept is validated here using a three-dimensional integrated numerical simulation.

• Nuclear Engineering and Technology
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• v.47 no.3
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• pp.323-331
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• 2015

Zirconium alloys are widely used in nuclear reactors as structural materials. During the operation, they are exposed to fast neutrons. Ion irradiation is used to simulate the damage introduced by neutron irradiation. In this article, we briefly review the neutron irradiation damage of zirconium alloys, then summarize the effect of ion irradiation on microstructural evolution, mechanical and corrosion properties, and their relationships. The microstructure components consist of dislocation loops, second phase precipitates, and gas bubbles. The microstructure parameters are also included such as domain size and microstrain determined by X-ray diffraction and the S-parameter determined by positron annihilation. Understanding the relationships of microstructure and properties is necessary for developing new advanced materials with higher irradiation tolerance.

• Macromolecular Research
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• v.9 no.3
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• pp.150-156
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• 2001

Polystyrenes(PS) were grafted onto polypropylene(PP) in the PP solution by ultrasonic irradiation-initiated polymerization of styrene. The resulting products consisted of mixtures of homopolymers and PP-PS copolymer because of the homopolymerization of styrene itself and copolymerization with PP. The dependency of the designated polymerization on sonication times was investigated to monitor the evolution lion of the copolymerization. Formation of the PP-PS copolymer was confirmed by FTIR analysis of the reaction products after a proper separation procedure of free PS and PP-PS copolymer. It was found that the tendency for the formation of PP-PS copolymer was closely related with the phase behavior of the PP/styrene mixture which was also influenced by sonication time. In order to verify the effectiveness of the PP-PS copolymer as a compatibilizer for PP/PS blend, melt mixing of PP/PS/PP-PS was performed in a batch mixer. During the mixing, the average torque was higher for the blend containing PP-PS copolymer influencing compatibilization. In accordance with the results from FRIR analysis and torque measurement, the PS domain size remarkably decreased in the PP/PS/PP-PS blend.

• Journal of Magnetics
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• v.14 no.2
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• pp.75-79
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• 2009

Nickel (Ni) and ferrite ($Fe_3O_4$, $NiFe_2O_4$) nanoparticles were synthesized by LGC using both wire feeding (WF) and micron powder feeding (MPF) systems. Phase evolution and magnetic properties were then investigated. The Ni nanopowder included magnetic-ordered phases. The LGC synthesis yielded spherical particles with large coercivity while the abnormal initial magnetization curve for Ni indicated a non-collinear magnetic structure between the core and surface layer of the particles. Since the XRD pattern cannot actually distinguish between magnetite ($Fe_3O_4$) and maghemite (${\gamma}-Fe_2O_3$) as they have a spinel type structure, the phase of the iron oxide in the samples was unveiled by $M{\ddot{o}}ssbauer$ spectroscopy. The synthesized Ni-ferrite consisted of single domain particles, including an unusual ionic state. The synthesized nanopowder bore an active surface due to the defects that affected abnormal magnetic properties.

• Journal of Microbiology and Biotechnology
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• v.20 no.12
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• pp.1696-1701
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• 2010

The ${\alpha}$-amylases activity was improved by random mutagenesis and screening. A region comprising residues from the position 34-281 was randomly mutated in B. licheniformis ${\alpha}$-amylase (AmyL), and the library with mutations ranging from low, medium, and high frequencies was generated. The library was screened using an effective liquid-phase screening method to isolate mutants with an altered pH profile. The sequencing of improved variants indicated 2-5 amino acid changes. Among them, mutant TP8H5 showed an altered pH profile as compared with that of wild type. The sequencing of variant TP8H5 indicated 2 amino acid changes, Ile157Ser and Trp193Arg, which were located in the solvent accessible flexible loop region in domain B.

• The Bulletin of The Korean Astronomical Society
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• v.41 no.1
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• pp.70.4-71
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• 2016

The links between super-massive black hole masses and their host galaxy properties are observed, indicating that black hole growth and host galaxy evolution are closely related. Reverberation mapping, which uses the time delay from the central black hole to broad line regions, is one of the best methods to estimate masses of black holes of active galactic nuclei (AGNs). However, only masses of about 50 black holes have been determined in reverberation mapping studies so far, and most of them are limited to optical luminosities below 10^45 erg/s due to the challenges of long-term time domain observations in both photometry and spectroscopy. In this project, we expand reverberation mapping samples to higher luminosities of > 10^44.5 erg/s at 0.1 < z < 0.35, that have expected time lags of 40 - 250 light days. Photometric (using LOAO 1-m and MDM 1.3-m) and spectroscopic (using MDM 2.4-m and Lick 3-m) monitoring campaigns are being conducted for a 3 year duration and 20 day cadence. Precedent photometric observations in 2015B show some targets with variability and follow-up spectroscopic observations are on-going. In this presentation, we introduce our project, present reverberation mapping simulation results, and preliminary results on photometry. These reverberation mapping masses of relatively high luminous AGNs will provide a strong constraint on black hole mass calibration, e.g., the single-epoch mass estimation.

• International Journal of Fuzzy Logic and Intelligent Systems
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• v.4 no.3
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• pp.327-336
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• 2004

In distributed autonomous mobile robot system, each robot (predator or prey) must behave by itself according to its states and environments, and if necessary, must cooperate with other robots in order to carry out a given task. Therefore it is essential that each robot have both learning and evolution ability to adapt to dynamic environment. This paper proposes a pursuing system utilizing the artificial life concept where virtual robots emulate social behaviors of animals and insects and realize their group behaviors. Each robot contains sensors to perceive other robots in several directions and decides its behavior based on the information obtained by the sensors. In this paper, a neural network is used for behavior decision controller. The input of the neural network is decided by the existence of other robots and the distance to the other robots. The output determines the directions in which the robot moves. The connection weight values of this neural network are encoded as genes, and the fitness individuals are determined using a genetic algorithm. Here, the fitness values imply how much group behaviors fit adequately to the goal and can express group behaviors. The validity of the system is verified through simulation. Besides, in this paper, we could have observed the robots' emergent behaviors during simulation.

• Journal of the Ergonomics Society of Korea
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• v.31 no.4
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• pp.557-565
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• 2012

Objective: This paper focuses on the new trend of applying NUI(natural user interface) such as gesture interaction into television and investigates on the design improvement needed in application. The intention is to find better design direction of NUI on television context, which will contribute to making new features and behavioral changes occurring in next-generation television more practically usable and meaningful use experience elements. Background: Traditional television is rapidly evolving into next-generation television thanks to the influence of "smartness" from mobile domain. A number of new features and behavioral changes occurred from such evolution are on their way to be characterized as the new experience elements of next-generation television. Method: A series of expert review by television UX professionals based on AHP (Analytic Hierarchy Process) was conducted to check on the "relative appropriateness" of applying gesture interaction to a number of selected television user experience scenarios. Conclusion: It is critical not to indiscriminately apply new interaction techniques like gesture into television. It may be effective in demonstrating new technology but generally results in poor user experience. It is imperative to conduct consistent validation of its practical appropriateness in real context. Application: The research will be helpful in applying gesture interaction in next-generation television to bring optimal user experience in.