• Transactions of the Korean Society of Automotive Engineers
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• v.11 no.2
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• pp.126-133
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• 2003

The aerodynamic characteristics of automobiles have received substantial interest recently. Detailed knowledge of the vehicle aerodynamics is essential to improve fuel efficiency and enhance stability at high-speed cruising. In this study, a numerical simulation has been carried out for three-dimensional turbulent flows around a commercial bus body. Also, the effect of rear-spoiler attached at rear end of bus body was investigated. The Wavier-Stokes equation is solved with SIMPLE method in general curvilinear coordinates system. RNG $k-\varepsilon$ turbulence model with the MARS scheme was used for the evaluating aerodynamic forces, velocity and pressure distribution. The results showed details of the three-dimensional wake flow in the immediate rear of bus body and the effect of rear-spoiler on the wake structure. A maximum of 14% reduction in drag coefficient was achieved for a model with a rear-spoiler.

• Journal of the Korea Society of Computer and Information
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• v.20 no.12
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• pp.91-99
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• 2015

In this paper, we introduce the application of several currently-representative methods for mineral resources potential assessment on Geographic information system(hereinafter referred to as GIS), and combined with mineral resources potential assessment performed in China and with lead-zinc deposits taken as an example, summarized and divided minerals prediction and assessment models; on this basis, this paper presented the process of metallogenic prognosis based on MRAS platform, and made a simple analysis on existing problems.

• Bulletin of the Korean Space Science Society
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• 2004.10b
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• pp.71-71
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• 2004

• Publications of The Korean Astronomical Society
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• v.30 no.2
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• pp.69-71
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• 2015

In our previous work, we investigated the orbital dynamics of Asteroid 1934 CT (or 1989 AC or 4179 Toutatis) from epoch 2012-Jul-24 (JDE2456132.5) using the Mercury program package. Asteroid 4179 Toutatis has an Earth and Mars crossing orbit with semimajor axis a = 2.5292 AU and eccentricity e = 0.6294, and therefore the perihelion distance is q = 0.9373 AU and the aphelion distance is Q = 4.1211 AU. After more than 300,000 years, asteroid 4179 Toutatis will escape from the Solar System, but during this time, it will have close-encounters with other planets from Venus to Uranus. As a continuation of this project, we investigated its energy changes in each close encounter. We also determine the energy of this asteroid when it escapes from the Solar System. The result is that during its orbital evolution, the energy of this asteroid changes and gives us negative, zero and positive values.

• Nuclear Engineering and Technology
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• v.42 no.6
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• pp.636-655
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• 2010

A thermal-hydraulic code, named CUPID, has been being developed for the realistic analysis of transient two-phase flows in nuclear reactor components. The CUPID code development was motivated from very practical needs, including the analyses of a downcomer boiling, a two-phase flow mixing in a pool, and a two-phase flow in a direct vessel injection system. The CUPID code adopts a two-fluid, three-field model for two-phase flows, and the governing equations are solved over unstructured grids with a semi-implicit two-step method. This paper presents an overview of the CUPID code development and assessment strategy. It also presents the code couplings with a system code, MARS, and, a three-dimensional reactor kinetics code, MASTER.

• The Bulletin of The Korean Astronomical Society
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• v.45 no.1
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• pp.57.1-57.1
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• 2020

The pandemic of COVID-19 has made it difficult to gather participants in offline astronomical programs since March, 2020. For this reason Gwacheon National Science Museum has developed online programs of the partial solar eclipse and the Asteroid Day event in June, the celebration for launching Mars 2020 in July and Perseids in August. In this poster, we present how to plan each of them and research on methods that deliver astronomical contents to viewers effectively. In addition, we introduce preparing a couple of online programs in the rest of this year.

• The KIPS Transactions:PartD
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• v.14D no.6
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• pp.573-584
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• 2007

As multimedia information recently increases fast, various types of retrieval of multimedia data are becoming issues of great importance. For the efficient multimedia data processing, semantics based retrieval techniques are required that can extract the meaning contents of multimedia data. Existing retrieval methods of multimedia data are annotation-based retrieval, feature-based retrieval and annotation and feature integration based retrieval. These systems take annotator a lot of efforts and time and we should perform complicated calculation for feature extraction. In addition. created data have shortcomings that we should go through static search that do not change. Also, user-friendly and semantic searching techniques are not supported. This paper proposes to develop S-MARS(Semantic Metadata-based Multimedia Annotation and Retrieval System) which can represent and extract multimedia data efficiently using MPEG-7. The system provides a graphical user interface for annotating, searching, and browsing multimedia data. It is implemented on the basis of the semantic metadata model to represent multimedia information. The semantic metadata about multimedia data is organized on the basis of multimedia description schema using XML schema that basically comply with the MPEG-7 standard. In conclusion. the proposed scheme can be easily implemented on any multimedia platforms supporting XML technology. It can be utilized to enable efficient semantic metadata sharing between systems, and it will contribute to improving the retrieval correctness and the user's satisfaction on embedding based multimedia retrieval algorithm method.

• Nuclear Engineering and Technology
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• v.41 no.5
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• pp.655-676
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• 2009

The first-ever integral effect test for simulating a guillotine break of a DVI (Direct Vessel Injection) line of the APR1400 was carried out with the ATLAS (Advanced Thermal-hydraulic Test Loop for Accident Simulation) from the same prototypic pressure and temperature conditions as those of the APR1400. The major thermal hydraulic behaviors during a DVI line break accident were identified and investigated experimentally. A method for estimating the break flow based on a balance between the change in RCS inventory and the injection flow is proposed to overcome a direct break low measurement deficiency. A post-test calculation was performed with a best-estimate safety analysis code MARS 3.1 to examine its prediction capability and to identify any code deficiencies for the thermal hydraulic phenomena occurring during the DVI line break accidents. On the whole, the prediction of the MARS code shows a good agreement with the measured data. However, the code predicted a higher core level than did the data just before a loop seal clearing occurs, leading to no increase in the peak cladding temperature. The code also produced a more rapid decrease in the downcomer water level than was predicted by the data. These observable disagreements are thought to be caused by uncertainties in predicting countercurrent flow or condensation phenomena in a downcomer region. The present integral effect test data will be used to support the present conservative safety analysis methodology and to develop a new best-estimate safety analysis methodology for DVI line break accidents of the APR1400.

• Journal of Energy Engineering
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• v.26 no.3
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• pp.64-70
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• 2017

The concept of Hybrid Safety Injection Tank (Hybrid SIT) proposed by the Korea Atomic Energy Research Institute (KAERI) has been introduced for the purpose of application to the Advanced Power Reactor Plus (APR+). In this study, the SBO situation of the APR+ was analyzed by using the MARS-KS code in order to evaluate whether the operation of the Hybrid SIT has an effect on the cooling performance of the Reactor Coolant System (RCS). According to the analysis, when the actuation valve on the pressure balancing line (PBL) is opened, the Hybrid SIT's pressure rises rapidly, forming equilibrium with the RCS pressure; subsequently, a flow is injected from the Hybrid SIT into the reactor vessel through the direct vessel injection (DVI) line. The analysis showed that it is possible to keep the core temperature below melting temperature during the operation of a Hybrid SIT.

• Culinary science and hospitality research
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• v.18 no.4
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• pp.59-69
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• 2012

This study examines the role of mathematics anxiety as a mediator between self efficacy and mathematics skills using a series of regression analyses suggested by Baron RM & Kenny DA(1986). The participants include college students who enrolled in the Food Service Production and Operation course in a department of hotel and restaurant management at a college in the United States. Descriptive analysis, principal component analysis, reliability test, and a series of regression analyses were used for data analysis using SPSS 19.0. In order to collect data for the study, General Self Efficacy Scale(GSES) and Math Anxiety Rating Scale(MARS) were utilized, and they turned out to be reliable(${\alpha}$=.906 and ${\alpha}$=.890, respectively). A significant negative relationship was found between self efficacy and mathematics anxiety. In addition, it was found that self-efficacious students performed better mathematics skills than those who had lower level of self efficacy. However, the relationship was no longer significant when the concept of mathematics anxiety was added, which satisfies the condition of mediation.