• Transactions of the Korean Society of Mechanical Engineers A
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• v.26 no.12
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• pp.2565-2573
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• 2002

A basic research was performed to ensure the usefulness of Small Punch-creep(SP-creep) test for residual life evaluation of heat resistant components effectively. This paper presents analytical results of initial stress and strain distributions in SP specimen caused by constant loading for SP-creep test and its experimental correlations with uniaxial creep(Ten-creep) test on 9Cr1MoVNb steel. It was shown that the initial maximum equivalent stress, ${\sigma}_{eq{\cdot}max}$ from FE analysis was correlated with steady-state equivalent creep strain rate, ${\epsilon}_{qf-ss'}$ rupture time, $t_r$, activation energy, Q and Larson-Miller Parameter, LMP during SP-creep deformation. The simple correlation laws, ${\sigma}_{sp}-{\sigma}_{TEN}$, $P_{sp}-{\sigma}_{TEN}\; and\; Q_{sp}-Q_{TEN}$ adopted to established a quantitative correlation between SP-creep and Ten-creep test data. Especially, the activation energy obtained from SP-creep test is linearly related to that from Ten-creep test at $650^{\circ}C$ as follows : $Q_{SP-P}\;{\risingdotseq}\;1.37 \;Q_{TEN},\; Q_{SP-{\sigma}}{\risingdotseq}1.53\; Q_{TEN}$.

• Journal of Digital Convergence
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• v.15 no.1
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• pp.199-208
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• 2017

This study investigates the components and rating system of reliable technology credit information for a technology finance donor who is a consumer of the information and aims to create an effective and optimal technology credit appraisal system to enlarge technology finance supply. Firstly, we calculate the optimal TCAR which becomes the maximum AUROC through the combination of ratio change, verify the substitution possibility between TAR and CR through the existing CR and system gap simulation, and propose a rating system by which financial institutes can utilize the TCAR as a credit rating. As a result, 70% : 30% is the most suitable as the weighted combination ratio of credit rating : technology rating. As a result of this study, we confirmed the possibility that the technical credit rating information could be substituted by the credit rating or the technology appraisal rating. Furthermore, it also suggests that sophisticated risk management is possible through using technology credit rating that are combined with credit and technology appraisal rating.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.47 no.5
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• pp.1-9
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• 2010

Generally, dynamic hand gesture recognition is formed through preprocessing step, hand tracking step and hand shape detection step. In this paper, we present advanced dynamic hand gesture recognizing method that improves performance in preprocessing step and hand shape detection step. In preprocessing step, we remove noise fast by using dynamic table and detect skin color exactly on complex background for controling skin color range in skin color detection method using YCbCr color space. Especially, we increase recognizing speed in hand shape detection step through detecting Start Image and Stop Image, that are elements of dynamic hand gesture recognizing, using Guideline. Guideline is edge of input hand image and hand shape for comparing. We perform various experiments with nine web-cam video clips that are separated to complex background and simple background for dynamic hand gesture recognition method in the paper. The result of experiment shows similar recognition ratio but high recognition speed, low cpu usage, low memory usage than recognition method using learning exercise.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.45 no.6
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• pp.38-43
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• 2008

Skin color information is an important feature for face region detection in color images. This can detect face region using statistical skin color model who is created from skin color information. However, due to the including of different race of people's skin color points, this general statistical model is not accurate enough to detect each specific image as we expected. This paper proposes method to detect correctly face region in various color image that other complexion part is included. In this method set face candidate region applying complexion Gausian distribution based on YCbCr skin color model and applied mathematical morphology to remove noise part and part except face region in color image. And achieved correct face region detection because using Haar-like feature. This approach is capable to distinguish face region from extremely similar skin colors, such as neck skin color or am skin color. Experimental results show that our method can effectively improve face detection results.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.28 no.5
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• pp.467-475
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• 2015

In this paper, the behaviour of a cantilevered beam was predicted to examine the difference between linear and non-linear static, dynamic analysis for a structure by using CR nonlinear formulation. Then, external transverse static and dynamic loads were applied at the free tip of the beam. Classical theories were used for the present linear analysis and co-rotational dynamic FEM program was used for the present nonlinear analysis. In the static analysis, effects of the load for the beam deflection were observed in both linear and nonlinear analysis. Then, normalized displacement at the tip of the beam was predicted for different frequency ratio and a significant difference was obtained in the vicinity of the resonant frequency. In addition, effects of frequency and time for the beam deflection were investigated to find the frequency delay.

• Journal of The Korean Association For Science Education
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• v.30 no.6
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• pp.739-751
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• 2010

The research reported in this study focused on an analysis of argumentation in the inquiry discourse among pre-service science teachers. For about 3 months, 7 groups of 24 pre-service science teachers participated in an open-ended inquiry and performed 10 inquiry discourses. All discourses were collected by video-recording and transcribed. To analyze features of argumentation discourse, analytic tools derived from Toulmin's argument pattern and cognitive argumentation scheme were applied to discussion transcripts. The results were as follows: First, the order of frequency in the analysis of 'meaning unit' was 'claim-warrant-data-rebuttal-backing.' Second, the order of frequency in the analysis of 'dialogue unit' was 'CW-CD-CDW-CWR-CR'. Third, more rebuttals were found than other discussions. Fourth, the second argumentative discussion showed a higher level than the first.

• Journal of the Society of Naval Architects of Korea
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• v.59 no.3
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• pp.157-163
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• 2022

An automatic mooring system for a ship consists of a vacuum suction pad and a mechanical part, enabling quick and safe mooring of a ship. In the development of a mooring system, the design of a vacuum suction pad is a key to secure enough mooring forces and achieve stable operation of a mooring system. In the vacuum suction pad, properly designing its rubber seal determines the performance of the suction pad. Therefore, it is necessary to appropriately design the rubber seal for maintaining a high-vacuum condition inside the pad as well as achieving its mechanical robustness for long-time use. Finite element analysis for the design of the rubber seal requires the use of an appropriate strain energy function model to accurately simulate mechanical behavior of the rubber seal material. In this study, we conducted simple uniaxial tensile testing of Chloroprene Rubber (CR) to explore the strain energy function model best-fitted to its experimentally measured engineering strain-stress curves depending on various temperature environments. This study elucidates the temperature-dependent mechanical behaviors of CR and will be foundational to design rubber seal for an automatic mooring system under various temperature conditions.

• Journal of the Korean Association of Geographic Information Studies
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• v.15 no.4
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• pp.124-137
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• 2012

Climate analysis is important in urban planning for human comfort. Synoptic weather conditions can only resolve the 30% of local variance of wind conditions whereas 70% of the variance arise from local terrain, buildings, and other small scale thermal conditions. Climate Analysis Seoul (CAS) was developed to resolve such micro-scale climate. The Local-scale air temperature Deviation (LD) analysis map from CAS showed the co-existence of built-up and suburban areas in the study region (CR, Cold-air analysis Region) despite its small extent. Temperature, humidity, wind speed, and wind direction were monitored in CR. Hourly observed cooling rate agreed well with LD. Cold air production, transportation, and stagnation was visualized by the observed Vertical Temperature Gradient (VTG) along the small stream in CR. VTG observed at the upper-most stream can be divided into two components: radiative cooling and cold air inflow from outside. Radiative cooling exists regardless of the wind speed whereas cold air inflow occurs only with calm wind. From the regression analyses based on the wind speed, the inflow portion was determined as 84% of radiative cooling. Climate analysis in the future will be able to characterize the changes in cold air by urban development plan to support the human comfort.

• Journal of Internet Computing and Services
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• v.12 no.4
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• pp.35-43
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• 2011

Cognitive Radio (CR) ad hoc network is highly considered as one of promising future ad hoc networks, which enables opportunistic access to under-utilized licensed spectrum. Similarly to other CR networks, the spectrum sensing is a prerequisite in CR ad hoc network. Collaborative spectrum sensing can help increasing sensing performance. For such an infrastructureless network, however the coordination for the sensing collaboration is really complicated due to the lack of a central controller. In this paper, we propose a novel collaborative spectrum sensing scheme in which the final decision is made by the node with the highest data reliability based on a sequential Dempster Shafer theory. The collaboration of sensing data is also executed by the proposed contention-aware reporting mechanism which utilizes the sensing data reliability order for broadcasting spectrum sensing result. The proposed method reduces the collecting time and the overhead of the control channel due to the efficiency of the ordered sequential combination while keeping the same sensing performance in comparison with the conventional cooperative centralized spectrum sensing scheme.

• Journal of the Korean Society of Radiology
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• v.10 no.7
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• pp.551-557
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• 2016

National competency standards, which are the contents of the knowledge, skills and attitudes required to perform a job in industry, is organized by the country. the job performance was evaluated based on the National competency standards from the third-year grade of radiology students by using field-based training courses. according to the evaluation results, students showed over 93% satisfactory ratio of job performance in all radiography projection methods. Therefore, it can be predicted that field-based training courses for students made a positive effect on improving their job performance. Exposure methods with CR equipment were evaluated the best rating, yet it has various problems. The standard deviation between students was very high, and the CR operation skill of students was insufficient. Film methods was evaluated also showed problems, due to the exposure condition setting and developing operation. although DR method was rated good to the students, it was evaluated that the operation skill of DR and the ancillary equipment operation skill was shortage. By supplementing the evaluation factors below proficiency levels to a course management in each exposure method, it could help students course achievement. Also, it could help students to improve job performance of clinical areas after graduation.