• Journal of the Korean Data and Information Science Society
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• v.26 no.1
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• pp.229-241
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• 2015

Nowadays, an open-market which provides sellers and consumers a cyber place for making a transaction over the Internet has emerged as a prevalent sales channel because of convenience and relatively low price it provides. However, there are few studies about CRM strategies based on VIP consumers for an open-market even though understanding VIP consumers' behaviors in open-markets is important to increase its revenue. Therefore, we propose CRM strategies targeted on VIP customers, obtained by analyzing the transaction data of VIP customers from an open-market using data mining techniques. To that end, we first defined the VIP customers in terms of recency, frequency and monetary (RFM) values. Then, we used data mining techniques to develop a model which best classifies and identifies infiluential factors customers into VIPs or non-VIPs. We also validate each of promotion types in the aspect of effectiveness and identify association rules among the types. Then, based on the findings from these experiments, we propose strategies from the perspectives of CRM dimensions for the open-market to thrive.

• Journal of the Korean Society of Propulsion Engineers
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• v.22 no.6
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• pp.28-36
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• 2018

A study was conducted to apply open-loop control to the combustion instability in a dump combustor using gaseous hydrocarbon fuels. Control power and frequency were varied by employing a loudspeaker under combustion conditions with similar characteristic chemistry times of the fuels. In the case of open-loop control where the frequency was identical to the combustion instability frequency, the open-loop control power affected the control performance. Results obtained from conducted open-loop control tests, where the frequency was different from the combustion instability frequency, show that setting the open-loop control frequency similar to the combustion instability frequency is effective.

• Journal of the Korean Society of Propulsion Engineers
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• v.24 no.2
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• pp.52-60
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• 2020

This paper deals with an optimal output tracking control for open-cycle liquid propellant rocket engine. For this purpose, we modeled simplified mathematical model of open-cycle liquid propellant rocket engine and designed optimal output feedback control system using combustion chamber pressure. For design the closed-loop system of open-cycle liquid propellant rocket engine, we designed optimal output feedback linear quadratic tracking control system using the linearized model and demonstrated the performance of the controller through numerical simulation.

• Nuclear Engineering and Technology
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• v.54 no.10
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• pp.3897-3908
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• 2022

High-fidelity nuclear data libraries and neutronics simulation tools are essential for the development of fast reactors. The IAEA coordinated research project on "Neutronics Benchmark of CEFR Start-Up Tests" offers valuable data for the qualification of nuclear data libraries and neutronics codes. This paper focuses on the verification and validation of the CEFR start-up modelling using OpenMC Monte-Carlo code against the experimental measurements. The OpenMC simulation results agree well with the measurements in criticality, control rod worth, sodium void reactivity, temperature reactivity, subassembly swap reactivity, and reaction distribution. In feedback coefficient evaluations, an additional state method shows high consistency with lower uncertainty. Among 122 relative errors in the benchmark of the distribution of nuclear reaction, 104 errors are less than 10% and 84 errors are less than 5%. The results demonstrate the high reliability of OpenMC for its application in fast reactor simulations. In the companion paper, the influence of cross-section libraries is investigated using neutronics modelling in this paper.

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 2004.11a
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• pp.257-257
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• 2004

• Proceedings of the Korean Information Science Society Conference
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• 2008.06a
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• pp.289-290
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• 2008

• Proceedings of the Korean Information Science Society Conference
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• 2007.06a
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• pp.109-110
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• 2007

• Bulletin of the Korean Mathematical Society
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• v.53 no.1
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• pp.205-214
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• 2016

Any open Riemann surface has a conformal model in any orientable Riemannian manifold of dimension 4. Precisely, we will prove that, given any open Riemann surface, there is a conformally equivalent model in a prespecified orientable 4-dimensional Riemannian manifold. This result along with [5] now shows that an open Riemann surface admits conformal models in any Riemannian manifold of dimension ${\geq}3$.

• Clinical and Experimental Pediatrics
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• v.53 no.8
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• pp.801-804
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• 2010

Purpose: This study aimed to evaluate the usefulness of the needle aspiration alternative to open surgical drainage of children with suppurative cervical lymphadenitis requiring surgical drainage. Methods: From January 1998 to June 2008, we retrospectively reviewed 38 children treated with needle aspiration as management with suppurative cervical lymphadenitis instead of open surgical drainage. Results: All 38 children underwent only 1 puncture. Two patients (5.2%) out of 38 patients experienced reformation of an abscess and all recovered completely after re-treatment with antibiotics. Minor complications were detected in 2 patients (5.2%). One complication originated from remnant necrotic tissue and the other involved formation of a small scar in two patients, which resolved spontaneously. There were no major complications. Conclusion: Needle aspiration can be a simple, safe, and effective alternative procedure to open surgical drainage of children with suppurative cervical lymphadenitis requiring surgical drainage.

• Proceedings of the IEEK Conference
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• 2008.06a
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• pp.761-762
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• 2008

This paper presents a hardware accelerator for accelerating vector graphics applications based on the OpenVG standard. Since our design mainly targets embedded applications, we focus on efficient uses of limited resources, especially the memory bandwidth. The designed accelerator can process the images of $640{\times}240$ pixels with moderate complexity at the rate of 30 frames per second.