• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2006.05a
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• pp.99-104
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• 2006

A semi-Lagrangian finite element scheme with objective time stepping algorithm for solving viscoelastic flow problem is presented. The convection terms in the momentum and constitutive equations are treated using a quasi-monotone semi-Lagrangian scheme, in which characteristic feet on a regular grid are traced backwards over a single time-step. Concerned with the generalized midpoint rule type of algorithms formulated to exactly preserve objectivity, we use the geometric transformation such as pull-back, push-forward operation. The method is applied to the 4:1 planar contraction problem for an Oldroyd B fluid for both creeping and inertial flow conditions.

• Knowledge Management Research
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• v.15 no.1
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• pp.45-63
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• 2014

Due to advance in Internet technology, most tourists tend to search travel information in the Online Travel Communities(OTC). Given this new paradigm in terms of finding travel information, most of relevant studies in this area are still dealt with explaining tourists' behaviors regardless of the types of communications. Therefore, to overcome some limitations in previous studies, we attempt to examine the relationships between both formal and informal communications and tourists' behavioral changes in the OTC context. Specifically, we developed a research model by employing the PPM(push-pull-mooring) framework and tested it to understand why and how tourists' behaviors might be changed. Survey data collected from 323 online tourists were used to test the model the model using SEM(structural equation modeling). The implications of our empirical findings for both research and practice are discussed.

• Proceedings of the KIEE Conference
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• 1995.07a
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• pp.368-370
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• 1995

A new three-level push-pull type quantum series resonant rectifier for the power factor correction is proposed. The proposed single phase rectifier enables a zero-current switching operation of all the power devices allowing the circuit to operate at high switching frequencies and high power levels. With the proposed control technique, an unity power factor and greatly reduced line current harmonics can be obtained.

• Applied Chemistry for Engineering
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• v.25 no.6
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• pp.624-631
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• 2014

In this study, a new series of conjugated polymer 3-(5-(5,6-bis(octyloxy)-7-(thiophen-2-yl)benzo[c][1,2,5]thiadiazol-4-yl)thiophen-2-yl)-10-(4-(octyloxy)phenyl)-10H-phenothiazine (P1) and 3-(5-(5,6-bis(octyloxy)-7-(thiophen-2-yl)benzo[c][1,2,5]thiadiazol-4-yl)thiophen-2-yl)-10-(4-((2-ethylhexyl)oxy)phenyl)-10H-phenothiazine (P2) were synthesised and organic photovoltaics (OPVs) properties were characterized. The push-pull structure polymer consisted of phenothiazine derivative as an electron donor and benzothiadiazole derivative as an electron acceptor. The aliphatic chain substituted aromatic ring was substituted at the position of N in phenothiazine for the electron-rich and improved solubility. Excellent thermal stabilities of P1 and P2 were confirmed by measured Td values as 321.9 and $323.7^{\circ}C$, respectively and the degrees of polymerization were 4,911 (P1) and 5,294 (P2). The maximum absorption wavelength of P1 and P2 were 549 and 566 nm, respectively. The device was fabricated and the OPVs property was measured. As a result, the power efficiency of conversion for P1 and P2 were 0.96 and 0.90%, respectively.

• Journal of Technology Innovation
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• v.6 no.2
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• pp.122-158
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• 1998

This study empirically examined different patterns of collaborative R&D project with their key success factors(KSFs), using data from 82 projects in the Korean electronic parts industry. The patterns of R&D collaboration were categorized into 4 types by two criteria development motive(technology Push/market pull) and Project initiator (focal firm/partner). The bivariate relationships revealed that project characteristics (technological complexity, market uncertainty), management characteristics (participation in project formulation), problem solving characteristics(problem solving performance of the focal firm, users active role in problem solving, active role of university or research institute in problem solving) and success rates appear to be different among four types of collaboration. Each type of collaborative R&D projects also had different KSFs. The KSFs of type 1 (technology Push and focal firm initiation), for instance, include the strategic importance of the project, focal firms share of cost, active role of university or research institute in problem solving, while those of type 4(market pull and customer initiation) cover reliability of partner relationship, a time at partners involvement, information sharing. The findings suggest that the different contingencies brought different patterns and KSFs of collaborative R&D project, since different information, resources, and partners roles were needed to successfully implement the projects according to development motive and project initiator Finally, managerial, policy, and theoretical implications for the collaborative R&D activities in the Korean electronics parts industry were discussed, based on empirical results of this study.

• Journal of the Korean Society of Clothing and Textiles
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• v.30 no.9_10 s.157
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• pp.1455-1463
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• 2006

The purpose of this study was to examine the advertisement effects of mobile fashion advertisements, specifically focusing on how the mobile fashion advertisement effects work according to advertisement types and categories. Two hundred female college students participated in this study. For data analysis, descriptive statistics, factor analysis, and t-test were used for this study. As the results, first, advertisement attitudes were classed into three factors such as cognitive factor emotional factor, and behavioral factor. Second, regarding the effect of advertisement types, pull advertisement type had higher advertisement attitudes, and higher purchasing intention than push advertisement type. There was not significant in brand attitudes between pull advertisement and push advertisement. Third, for the effects of advertisement categories, clothing advertisement had higher cognitive factor and behavioral factor, and higher purchasing intention than accessory advertisement. There were not significant in emotional factor and brand attitude between clothing and accessory advertisements. Based on these results, M-commerce fashion advertisement marketing strategies would be suggested.

• Journal of the Ergonomics Society of Korea
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• v.22 no.2
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• pp.57-69
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• 2003

This study was performed to investigate the isometric endurance time as percentages of maximum voluntary contraction. Electromyogram(EMG) and Borg's CR-I0 value were measured by push-pull-up-down tasks for 10 healthy males. The normalized EMG value and the MPF(mean power frequency) were used to estimate the muscle recruitment pattern and the development of muscle fatigue. The subjects exerted and maintained 5 levels of %MVC(maximum voluntary contraction) in $90^{\circ}$ shoulder flexion/ 180oelbow extension at sitting posture. The up-task showed the lower endurance time and higher Borg's CR-I0 value than the other task types. Comparing Rohmert's curve with the endurance time of task types. Rohmert's curve overestimated the endurance time of up-task and underestimated the endurance time of push-pull-down tasks. The normalized EMG value showed that muscles recruitment patterns were different from task types. The 4 muscles(biceps brachii muscle, tricep brachii muscle. middle deltoid muscle. trapezius muscle) recruitment patterns of up-task were higher than those of other tasks. The MPF value decreased with the endurance time, and the shift of MPF at up-task was larger than that of the other task types.

• Proceedings of the KSR Conference
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• 2008.06a
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• pp.1227-1232
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• 2008

High-speed train of push-pull type called as G7 train has been developed and chosen as the model of KTX-II which will be operated on Honam Line nexr year. However, the EMU-type high-speed train appeared to be the recent trend that foreign markets have shown. Also, in the near future, a great number of new train sets are needed to accommodate the increased passengers in our country. Thus, development of the high-speed EMU was decided, planned, and started. In the development, included were almost all fundamental key technologies such as noise and vibration reduction in a passenger cabin, running characteristics, aerodynamic analysis, crashworthiness evaluation, EMI/EMC analysis, design of the cooling system for the propulsion control system, enhanced performance of transformer and switching converters, synchronous traction motor with permanent magnets, new design of front nose and ergonomic interiors, application of advanced information technology(IT) and smart sensors and the cost reduction of construction of railway bridges, etc. Each key technologies are carried out as sub-project independently but under the supervision of a project. The project will develop the high advanced level of technologies and provide necessary know-why's and support the team in charge of the development of the high-speed EMU, Hyundai Rotem Co. Ltd. The high-speed EMU will be successfully developed with the support of the project.

• The Transactions of the Korean Institute of Power Electronics
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• v.12 no.3
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• pp.199-204
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• 2007

In this paper, EEFL, which is advantageous for driving multi-lamp and is able to reduce number of inverter, is used and Piezoelectric Transformer, which is able to reduce self loss, miniaturize and has high boosting transfer rate, and parallel connected to drive multi-lamp. For optimized EEFL driver circuit configuration, a Push-Pull type Piezoelectric inverter was designed and a simulation analysis was performed on the inverter circuit, and by applying multiple different type of driving methode, it is proved that a piezoelectric transformer can be used to manufacture a big screen multi-lamp driving inverter.

• Proceedings of the Korea Information Processing Society Conference
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• 2007.05a
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• pp.870-872
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• 2007

Sensor networks have been widely applied for data collection. Due to the energy limitation of the sensor nodes and the most energy consuming data transmission, we should allocate as much work as possible to the sensors, such as data compression and aggregation, to reduce data transmission and save energy. Querying extreme values is a general query type in wireless sensor networks. In this paper, we propose a novel querying method called Two-Level Filter (TLF) for querying extreme values in wireless sensor networks. We first divide the whole sensor network into domains using the Distributed Data Aggregation Model (DDAM). The sensor nodes report their data to the cluster heads using push method. The advantages of two-level filter lie in two aspects. When querying extreme values, the number of pull operations has the lower boundary. And the query results are less affected by the topology changes of the wireless sensor network. Through this method, the sensors preprocess the data to share the burden of the base station and it combines push and pull to be more energy efficient.