• Journal of applied mathematics & informatics
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• v.22 no.1_2
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• pp.113-124
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• 2006

In this paper we consider the numerical solution of the sunflower equation. We prove that if the sunflower equation has a Hopf bifurcation point at a = ao, then the numerical solution with the Euler-method of the equation has a Hopf bifurcation point at ah = ao + O(h).

• The Journal of Korean Institute of Communications and Information Sciences
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• v.11 no.5
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• pp.360-369
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• 1986

An AO TIC system for performing real-time correlation of two signals is constructed. It uses AOD(Acoustooptic Device) and CCD(Charge Coupled Device). An acoustooptic technique for achieving signal correlation isdescribed. The statistical analysis for correlator's output SNR is presented and experimental procedure for implemention of this technique are result shown. Since the correlation intergration is performed in time rather thatn space, the SNR of this system can be greatly improved.

• IE interfaces
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• v.13 no.4
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• pp.709-716
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• 2000

In this paper, We analyze a capacity dimensioning and performance of the access line to the X.25 packet network when the AO/DI internet service is connected via D-channel. We show the forecasting methodology of the traffic demand of the D-channel internet services when the TDX-1OA switching system accommodates the target number of subscriber. Based on the traffic demand forecast, the required capacity of the access line is suggested to prevent bottleneck problem in the access line to the X.25 packet network.

• Korean Journal of Microbiology
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• v.42 no.1
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• pp.47-53
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• 2006

A streptomycete strain was isolated from the soil samples from Korea. The chemotaxonomy and 16S rDNA sequencing confirmed that the strain belonged to the genus Streptomyces and we named it Streptomyces sp. AO-0511. Two antibiotics, herbimycin A and dihydroherbimycin A produced by this strain were tested for their physico-chemical and biological characteristics. Both compounds were stable under acidic pH. Dihydroherbimycin A was more heat-stable and polar compared with herbimycin A. Only weak antibacterial activities were detected against Bacillus subtilus ATCC 6633 and Micrococcus luteus ATCC 9341. However, herbimycin A and dihydroherbimycin A showed strong inhibitory activities on lung cancer cells (A549 cells) and leukemia cells (HL-60). The cytotoxicity was determined using L5178Y and P388 cell lines. The results showed that herbimycin A and dihydroherbimycin A had lower toxic effects on the cells compared with the standard compounds, comptothecin and cyclosporin A. Therefore, both compounds could be good candidates for the development of new anticancer drugs.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.20 no.3
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• pp.499-505
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• 2016

In this Paper, we propose a body-area localization technique based on WUSB (Wireless USB) over WBAN (Wireless Body Area Networks) protocol required for wearable computer systems. The proposed localization algorithm is executed on the basis of WUSB over WBAN protocol at each sensor node comprising peripherals of a wearable computer system. To increase the accuracy of input information through various body motions in wearable computer systems, a new localization technique with high precision must be developed. To achieve the goal, This paper proposes a combined TDoA/FDoA/AoA (Time Of Arrival/Time Difference Of Arrival/Angle Of Arrival) localization technique with more than four WUSB over WBAN devices to estimate body-area location accurately. The combined TDoA/FDoA/AoA technique reduces 10mm in location estimation errors comparing with a combined TDoA/FDoA technique. This performance enhancement in location error reduction can be ignored at other systems but is meaningful results in body-area localization-based communications.

• Ocean and Polar Research
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• v.38 no.2
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• pp.89-102
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• 2016

In this study, we evaluated the model performance with respect to Sea Surface Temperature (SST) and Net Heat Flux (NHF) by considering the characteristics of seasonal temperature variation and contributing factors and by analyzing heat budget terms in the Northwestern Pacific and East Asian Marginal Seas ($110^{\circ}E-160^{\circ}E$, $15^{\circ}N-60^{\circ}N$) using the HadGEM2-AO historical run. Annual mean SST of the HadGEM2-AO is about $0.065^{\circ}C$ higher than observations (EN3_v2a) from 1950 to 2000. Since 1960, the model has simulated well the long-term variation of SST and the increasing rate of SST in the model ($0.014^{\circ}C/year$) is comparable with observations ($0.013^{\circ}C/year$). Heat loss from the ocean to the atmosphere was simulated slightly higher in the HadGEM2-AO than that in the reanalysis data on the East Asian Marginal Seas and the Kuroshio region. We investigated the causes of temperature variation by calculating the heat budget equation in the two representative regions. In the central part of the Kuroshio axis ($125^{\circ}E-130^{\circ}E$, $25^{\circ}N-30^{\circ}N$: Region A), both heat loss in the upper mixed layer by surface heat flux and vertical heat advection mainly cause the decrease of heat storage in autumn and winter. Release of latent heat flux through the heat convergence brought about by the Kuroshio contributes to the large surface net heat flux. Positive heat storage rate is mainly determined by horizontal heat advection from March to April and surface net heat flux from May to July. In the central part of the subtropical gyre ($155^{\circ}E-160^{\circ}E$, $22^{\circ}N-27^{\circ}N$: Region B), unlike Region A, vertical heat advection predominantly causes the decrease of heat storage in autumn and winter. In spring and summer, surface heat flux contributes to the increase of heat storage in Region B and the period is two times longer than the period for Region A. In this season, shoaling of the mixed layer depth plays an important role in the increase of SST.

• The Korean Journal of Ecology
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• v.26 no.1
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• pp.13-18
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• 2003

We examined water flux, concentrations and contents in nutrients in precipitation, throughfall, stemflow and soil solution in natural deciduous hardwood forest(Quercus variabilis and Q. mongolica) in Chunchon, Kangwon Province. The volume of throughfall was 2∼3% higher in Q. variabilis than in Q. monglica while volume of stemflow, Ao, A and B soil solution was 10∼15% higher in Q. variabilis compared to Q. monglica. Concentrations of K/sup +/ increased in throughfall H while concentrations of Ca/sup 2+/, Mg/sup 2+/ and NO₃/sup -/ increased in Ao soil solution. The former might be related to the canopy leaching and the latter related to leaching and nitrification in Ao horizon. Nutrient concentrations in throughfall, Ao, A and B soil solution decreased with increasing amount of water and especially the decreases in concentrations of K/sup +/, Mg/sup 2+/ and Cl/sup -/ were significant. Nutrient concentrations of Ca/sup 2+/ in Ao soil solution was 1.5 times higher in Q. variabilis than in Q. mongolica. However, there were no significant nutrient concentration differences in throughfall, stemflow and A and B soil solution between the two forest types. Stemflow was less than 10% of total water volume (throughfall + stemflow) to the forest floor, and contribution of stemflow to nutrient cycling seemed to be low in the study forest.

• The Bulletin of The Korean Astronomical Society
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• v.38 no.1
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• pp.68.2-68.2
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• 2013

The Giant Magellan Telescope Integral-Field Spectrograph (GMTIFS) is a near-infrared imager and integral-field spectrograph, which will be the workhorse adaptive-optics (AO) instrument on the GMT when AO operations begin. We will describe the current design and proposed capabilities of the GMTIFS. We will also present a brief overview of GMTIFS science cases that include first-light objects, galaxy feedback and assembly, the nature of compact massive objects as well as the formation and evolution of stars and planets.

• The Journal of the Korea institute of electronic communication sciences
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• v.17 no.5
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• pp.889-896
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• 2022

Data required in a wireless sensor network environment requires more accurate figures as technology advances and its complexity increases. However, in the case of operating a large number of sensor nodes in a large area, the balance between the power consumed and the data quality that can be acquired accordingly should be considered for that purpose. In particular, in complex, densely populated urban areas or military operations with specific goals, location data requires increasingly detailed and high accuracy over a wide range. In this paper, we propose a method of mounting a Global Positioning System(: GPS) only on some of the sensor nodes deployed in the wireless sensor network and improving the error of GPS location data measured on that sensor node through Angle of Arrival(: AoA) and Received Signal Strength Indicator(: RSSI).

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.9
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• pp.3841-3848
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• 2012

The process of an analysis of alternatives(AoA) attempts to select the best and balanced solution among a set of multiple candidate solutions under the constraints of cost, schedule, performance and risk(CSPR). The traditional AoA for the acquisition of a new weapon system has usually centered on the sequence of the requirement analysis, design synthesis, and cost estimation. An improved process for AoA is developed in this paper based on a multi-objective decision-making method, which is intended to be applied in the design concept refinement and material solution analysis stage for the acquisition of naval surface ships. The presentation of the proposed AoA approach is then followed by a case study for the next generation multi-purpose training ship based on the principles of systems engineering and also using the models of the effectiveness measure, cost estimation, and risk assessments.