• Journal of the Korea Institute of Information and Communication Engineering
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• v.17 no.10
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• pp.2281-2287
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• 2013

Network Coding(NC) is a new paradigm for network communication. In network coding, intermediate nodes create new packets by algebraically combining ingress packets and send it to its neighbor node by broadcast manner. Network Coding has rapidly emerged as a major research area in information theory due to its wide applicability to communication through real networks. Network coding is expected to improve throughput and channel efficiency in the wireless multi-hop network. Prior researches have been carried out to employ network coding to wireless ad-hoc network. In our study, intermediate nodes identify one-hop bidirectional flows for network coding decision. We expect that the proposed scheme shall improve decoding success rate of network coded packet. From the simulation, the proposed network coding scheme achieved better performance in terms of coding gain and packet delivery rate than traditional network coding scheme.

• Korean Journal of Child Studies
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• v.6 no.2
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• pp.21-33
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• 1985

This study was conducted to ascertain whether a didactic mode of instruction, favored students who indicated a preference for left hemispheric information processing. The subjects were 50 fifth grade students whose California Achievement Test score percentile ranks were between 50 - 80. They were randomly selected from one elementary school in Chapel Hill, NC, USA. All Ss completed the Form CC of "Your Style of Learning and Thinking" (Torrance and McCarthy, 1980) which is a paper/pencil inventory designed to categorize the subjects according to their hemispheric preference for processing information; right hemisphere, left hemisphere, and integrated. Then all Ss received a didactic mode of instruction, a verbal question/answer followed by teacher's reading of a fictional animal story, "The Chinese Bee-eater". After completion of instruction, the Ss were asked to respond to eighteen open-ended questions about the animal. Eight of the 50 subjects were found to fall into the right hemisphere style of information processing group; fourteen into left; and fourteen into integrated. The remaining fourteen could not be assigned to either of these three categories and were not included in the analysis of the results. the mean scores of the comprehensive test among hemispheric groups and among sex groups. A two way analysis of variance also presented no significant differences among the hemispheric preference combined by sex groups. These results failed to prove the research hypothesis that students who indicate a preference for left hemispheric information processing will have higher scores on a comprehensive test after receiving a didactic mode of instruction, the so-called left style of instruction. Some limits in research process and conceptual confusion about hemisphericity were discussed. Finally, it was suggested that educators need to be more careful in drawing educational implications from neurological hemispheric research.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.19 no.7
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• pp.67-72
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• 2005

If the PNC is shutting down or wants to leave the WPAN, it uses the handover process to give control to another device in the piconet. However when the PNC is selected, only the device capability information is checked in the WPAN standard specification and no detail criteria is described. In this paper, the PNC selection method with considering the number and density of device to maximize the piconet data throughput in the WPAN is studied. From the numerical analysis results, the considering with the devices concentration has higher data throughput compared with the uniform distribution. For the efficient performance, the device distribution within the piconet should be considered in the PNC selection.

• Journal of Multimedia Information System
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• v.6 no.4
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• pp.209-216
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• 2019

Over the past decade, researchers were able to solve complex medical problems as well as acquire deeper understanding of entire issue due to the availability of machine learning techniques, particularly predictive algorithms and automatic recognition of patterns in medical imaging. In this study, a technique called transfer learning has been utilized to classify Magnetic Resonance (MR) images by a pre-trained Convolutional Neural Network (CNN). Rather than training an entire model from scratch, transfer learning approach uses the CNN model by fine-tuning them, to classify MR images into Alzheimer's disease (AD), mild cognitive impairment (MCI) and normal control (NC). The performance of this method has been evaluated over Alzheimer's Disease Neuroimaging (ADNI) dataset by changing the learning rate of the model. Moreover, in this study, in order to demonstrate the transfer learning approach we utilize different pre-trained deep learning models such as GoogLeNet, VGG-16, AlexNet and ResNet-18, and compare their efficiency to classify AD. The overall classification accuracy resulted by GoogLeNet for training and testing was 99.84% and 98.25% respectively, which was exceptionally more than other models training and testing accuracies.

• Journal of the Korean Society of Tobacco Science
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• v.16 no.2
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• pp.122-127
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• 1994

Feeding preference of cigarette beetle, Lasioderma sewicorne F., on cured tobacco leaves was investigated to obtain basic information on ecological management of the insect pest in tobacco storage warehouses. About 3, 000-4, 000 adults of the insect were released in a warehouse in which groud tobacco leaves were placed on the bottom and at 3m above the floor level, and numbers of insects attracted were examined. There was no significant difference on feeding preference between the two tobacco varieties, flue-cured(NC82) and air-cured(Br3l) tobacco leaves. However, significant differences were noted in feeding preference between thick and thin leaves and among different quality grades within a tobacco variety. Feeding preferences of cigarette beetle between flue- and air- cured tobacco varieties showed significant differences on the lower position, though there were no differences on the 3m upper position. On the 3m upper position, feeding preferences were different between thick and thin leaves of tobacco varieties, and variety X thickness and variety X thickness equality grades showed statistically significant differences. Significantly higher feeding preference by cigarette beetle adults was observed for the food placed on the 3m upper than on the lower position. There were negative correlations between quality grades of cured tobacco leaves and feeding preference on the lower position, and the regression equation was Y(feeding preference)=4.050-0.683 X (degree).

• Korean Journal of Computational Design and Engineering
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• v.6 no.2
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• pp.89-100
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• 2001

Swept volume is the sweeping region of moving objects. It is used in various applications such as interference detection in assembly design, visualization of manipulator motions in robotics, simulation of the volume removal by a cutter in NC machining. The shape of swept volume is defined by the envelope, which is determined by the boundary of moving objects and its direction of motion. In order to implement the generation of swept volume, researchers have taken much effort to develop the techniques how to generate the envelope. However, their results are confined to envelope generated only in simple shape objects, such as polyhedra or quadric surfaces. This study provided the envelope generation algorithm of NURBS objects. Characteristic points were obtained by applying the geometric conditions of envelope to NURBS equations, and then characteristic curves were created by means of interpolating those points. Silhouette edges were determined in the following procedures. First, two adjacent surfaces which have the same edge were found from B-Rep data. Then, by taking the scalar product of velocity vector of a point on that edge with each normal vector on two surfaces, silhouette edges were discriminated. Finally, envelope was generated along moving direction in the form of ruled surfaces by using both the partial information between initial and final position of objects affecting envelope along with characteristic curves and silhouette edge. Since this developed algorithm can be applied not only to NURBS objects but also to their Boolean objects, it can be used effectively in various applications.

• Journal of the Society of Naval Architects of Korea
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• v.52 no.5
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• pp.372-379
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• 2015

The blade root fillets which have strong influences on the performance of propellers in the both structural and hydrodynamic points of view, are mechanical parts for smooth connection surface with a blade and a hub. A few related researches (Sabol, 1983; Kennedy, 1997) have noted that 3T-T/3 double radius section design would be suitable for reducing Stress Concentration Factor(SCF) and increasing Cavitation Inception Speed(CIS). In this paper, it is confirmed that this compound cross-section design has come close to the optimum solution in the shape optimization standpoint so that it could protect the propeller blade under the frequent and various loading cases. On that basis, we suggest the definite and simple fillet design methodology that has the cross-section with nT-T/n compound radius and elliptic shape which could sustain the given derivatives information as well as the offsets at the boundary and all inner region of the fillet surface. In addition, the result of design is presented in form of IGES file format in order to connect with NC machine seamlessly.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.27 no.11
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• pp.1958-1966
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• 2003

Three-axis CNC surface machining entails a series of processes including rough cutting, intermediate cutting and finish cutting for a reference surface defined in CAD/CAM. This study is targeting development of an integrated NURBS surface interpolator that can incorporate rough, intermediate and finish cutting processes. In each process, volume to be removed and cutting condition are different according to the shape of a part to be machined and the reference surface. Accordingly, the proposed NURBS surface interpolator controls motion in real-time optimized for the machining conditions of each process. In this paper, a newly defined set of G-codes is proposed such that NURBS surface machining through CNC is feasible with minimal information on the surface composition. To verify the usefulness of the proposed interpolator, through computer simulations on NURBS surface machining, total machining time, size of required NC data and cutting force variations are compared with the existing method.

• Journal of Integrative Natural Science
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• v.1 no.2
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• pp.79-83
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• 2008

As a new standard for performance measurement, NEMA NU2-2001 was presented recently. In this study, I investigated the spatial resolution, sensitivity, scatter fraction, and noise equivalent count ratio (NECR) in order to know the information of physical characteristics and system performance of GE discovery ST using this new standard. Bismuth germinate crystals ($6{\times}6$ array, $6.3mm{\times}6.3mm{\times}30mm$) were used in discovery ST (energy window:375-650 keV, coincidence window:11.7 nsec). To measure the sensitivity, five aluminum sleeves (Data Spectrum Corp., Chapel Hill, NC., USA, thickness:1.25 mm)-NEMA sensitivity phantom- filled with F-18 solution were used. Successive measurements in 2D and 3D acquisition mode were made with a line source at the center of transaxial field of view and 10 cm off from the center until the count was over 500,000. Spatial resolution was estimated using a point source (F-18, 0.1 mCi) at different locations in the FOV. Scatter fraction and NECR was tested using a NEMA scatter phantom. Dynamic data were acquired for 7 half-lives using F-18 solution. And true to background ratio was averaged at last three frames when the random rate was as small as ignorable for the calculation of scatter fraction. We anticipate this overall evaluated results could be used for the quality assurance and optimized image acquisition for clinical research.

• Journal of the Earthquake Engineering Society of Korea
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• v.24 no.4
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• pp.179-187
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• 2020

Seismic qualification of equipment including piping is performed by using floor response spectra (FRS) or in-structure response spectra (ISRS) as the earthquake input at the base of the equipment. The amplitude of the FRS may be noticeably reduced when obtained from coupling analysis because of interaction between the primary structure and the equipment. This paper introduces a method using a modal synthesis approach to generate the FRS in a coupled primary-secondary system that can avoid numerical instabilities or inaccuracies. The FRS were generated by considering the dynamic interaction that can occur at the interface between the supporting structure and the equipment. This study performed a numerical example analysis using a typical nuclear structure to investigate the coupling effect when generating the FRS. The study results show that the coupling analysis dominantly reduces the FRS and yields rational results. The modal synthesis approach is very practical to implement because it requires information on only a small number of dynamic characteristics of the primary and the secondary systems such as frequencies, modal participation factors, and mode shape ordinates at the locations where the FRS needs to be generated.