• KSII Transactions on Internet and Information Systems (TIIS)
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• v.13 no.1
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• pp.186-205
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• 2019

Intercell interference coordination (ICIC) is considered as a promising technique to increase the spectral efficiency of OFDMA cellular systems. The soft frequency reuse (SFR) and fractional frequency reuse (FFR) are representative and efficient management techniques for ICIC. Herein, to enhance the performance of the SFR scheme, we propose a call admission (CAC) scheme. In this CAC scheme, called Spectrum handoff-SFR(S-SFR), the spectrum handoff technique is applied to the user equipment (UE) located near the cell center. We derive the traffic analysis model to describe the S-SFR. In addition, a two-dimensional (2-D) Markov chain and an outage analysis are used in our analytical model. From the traffic analysis, the significant performance measures are the outage probability, call blocking probability, system throughput and resource utilization. Based on those, the outage probability and system throughput are obtained using resource utilization as an interference pattern. The analytical results are verified with computer simulation results. Finally, we compare our proposed scheme with other ICI schemes.

• Journal of the Korean Society for Precision Engineering
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• v.11 no.1
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• pp.54-62
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• 1994

This paper presents active control methodologies to suppress structural deflections of a composite beam using a distributed piezoelectric-film actuator and sensor. Three types of different controllers are employed to achieve vibration suppression. The controllers are established depending upon the information on the velocity components of the structrue and on the deflection magnitudes as well. They are constant-amplitude controller(CAC), constant-gain mcontroller(CGC), and constant-amplitude-gain controller(CAGC). For the minimization of the residual vibration (chattering in a settled phase), which is the practical shortcoming of the conventional CAC dur to time delay phenomenon of the hardware system, a new control algoritym CAGCis designed by selecting switching constants in an optimal manner with respect to the initial tip deflection and the applied voltage. The experimental investigations of the transient and forced vibration control for the first vibrational mode are undertaken in order to compare the suppression efficiency of each control algorithm. Moreover, simultaneous controllability of various vibrational modes through the proposed scheme is also experimentally verified by pressenting both the transfer function and the phase.

• Journal of the Korean Society of Food Science and Nutrition
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• v.43 no.12
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• pp.1801-1807
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• 2014

Blue mussels (Mytilus edulis) are widely distributed among the world's oceans in various habitats. The purpose of this study was to investigate the effects of freeze-drying on the antioxidant and antigenotoxic activities of blue mussels collected in the Gyeongnam coast area of Korea. Raw (RM) and freeze-dried blue mussel flesh (FRM) were extracted with ethanol, methanol, and water. Antioxidant activities were evaluated on the basis of DPPH radical scavenging activity, oxygen radical absorbance capacity (ORAC), cellular antioxidant capacity (CAC), and antigenotoxic activity (comet assay). Except for the water extract, RM and FRM showed DPPH radical scavenging activities, which increased upon freeze-drying in MeOH extract. The highest ORAC value was observed in water extract of RM and MeOH extract of FRM. CAC was protected against AAPH-induced oxidative stress in HepG2 cells by both RM and FRM extracts. Freeze-drying lowered ORAC value of water extract, whereas it increased CAC activity, suggesting that antioxidant activities varied according to the generated radicals. All extracts from RM and FRM showed antigenotoxic activities by reducing $H_2O_2$-induced DNA damage in human leukocytes. Freeze-drying had no effect on antigenotoxicity of blue mussels. Taken together, these results indicate that blue mussels possess antioxidant and antigenotoxic properties, and freeze-drying might be a useful processing method for blue mussels to retain their maximum physiological potential as a functional food.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.10a
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• pp.145-145
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• 2003

• Ingenium
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• v.14 no.3
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• pp.20-23
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• 2007

• Journal of Information Management
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• v.10 no.4
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• pp.126-131
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• 1977

• Structural Engineering and Mechanics
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• v.56 no.4
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• pp.605-623
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• 2015

A formulation of the boundary element method (BEM) based on Kirchhoff's hypothesis to analyse stiffened plates composed by beams and slabs with different materials is proposed. The stiffened plate is modelled by a zoned plate, where different values of thickness, Poisson ration and Young's modulus can be defined for each sub-region. The proposed integral representations can be used to analyze the coupled stretching-bending problem, where the membrane effects are taken into account, or to analyze the bending and stretching problems separately. To solve the domain integrals of the integral representation of in-plane displacements, the beams and slabs domains are discretized into cells where the displacements have to be approximated. As the beams cells nodes are adopted coincident to the elements nodes, new independent values arise only in the slabs domain. Some numerical examples are presented and compared to a wellknown finite element code to show the accuracy of the proposed model.

• Bulletin of the Korean Chemical Society
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• v.34 no.11
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• pp.3377-3380
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• 2013

The spectrophotometric and electrochemical properties of tetraazo(p-carboxy)phenylcalix[4]arene (p-CAC) in the presence of various metal ions were investigated by UV/Vis spectroscopy and voltammetry in $CH_3CN$. p-CAC showed selective color changes to $Cu^{2+}$ over other metal ions from light orange to colorless, in accordance with hypsochromic shift in UV/Vis spectra. Voltammetric measurements also showed high selectivity for $Cu^{2+}$.

• ETRI Journal
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• v.29 no.1
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• pp.113-115
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• 2007

A dynamic tri-threshold call admission control scheme has been developed. This scheme supports voice, data, and multimedia services and it complies with the universal mobile telecommunications system. The performance of the proposed scheme is evaluated under varying handover rates. The QoS performance-including channel utilization, call dropping probability, and blocking probability-is investigated. The performance of the developed scheme is found to be encouraging.

• Proceedings of the KIPE Conference
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• 2013.07a
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• pp.339-340
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• 2013

본 논문은 지능형 실외기인 CAC, PAC 에어컨 실외기의 Interleaved PFC단에 사용하는 리액터에 관한 것으로써, 리액터의 부피 및 가격 저감을 목표로 하고 있다. 기존 6KW급 CAC, PAC 에어컨 실외기의 Interleaved PFC단에 사용하는 두 개의 개별 리액터를 한 개의 코어를 이용한 커플 인덕터 방식의 리액터로 대체한다. 이를 통해, 리액터의 부피 및 가격 저감이 가능하다. 실제 제품에 적용하여 실험한 결과, 기존과 동등한 수준의 입력 전류와 인덕터 전류 리플을 갖고, 역률 또한 개선됨을 검증하였다.