• Journal of The Korean Association of Information Education
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• v.14 no.3
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• pp.437-447
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• 2010

The purpose of this thesis was to design and develop an effective e-PBL(Problem-Based Learning) for cultivating consciousness of information and communication ethics. The proposed e-PBL is based on PBL which is one of the constructivism teaching-learning theories. Online learning and face-to-face classes were systematically combined for achieving the teaching-learning goals. And the main module for online learning run on Moodle, an open source learning management system. To examine educational effectiveness of the proposed e-PBL, an experimental study was conducted through the education content and method to the subject of two class in the second-grade of university located in OO city. For experiment 60 students(treatment group=30, control group=30) are participated. And they were randomly assigned to one of ten subgroups, comprising of six students, respectively. The results of this study showed that the education using proposed e-PBL is more effective in cultivating consciousness of information and communication ethics and learners responded positively than the education using traditional face-to-face PBL learning method.

• Korean Journal of Optics and Photonics
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• v.16 no.1
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• pp.63-70
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• 2005

We propose a method for evaluating the image quality of color liquid crystal display(LCD) monitors by using the polychromatic modulation transfer function(PMTF), which is calculated from the modulation transfer function(MTF) weighted by the overall color response of the system including the test LCD monitor. We confirm that experimental results using the PMTF agree well with simulated results of the PMTF of a color LCD monitor by using three bar targets with different amplitudes and three elementary colors such as red(R), green(G), and blue(B). As a results, we should choose the PMTF instead of the white color MTF or monochromatic MTF in order to evaluate correctly the image quality of color LCD monitors.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.41 no.4
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• pp.285-291
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• 2017

In this study, a case analysis for thermal design of electronic equipment using a phase change material(PCM) was performed numerically using ANSYS Fluent. Experiments were conducted to find the temperature increase(${\Delta}T_m$), melting temperature($T_m$), and volume expansion of the PCM under the melting process. To verify the accuracy of the Fluent solver model, $T_m$, ${\Delta}T_m$, and the melting time were compared with experimental results. To simulate the temperature stagnation phenomenon under the melting process, the equivalent specific heat method was applied to calculate the thermal properties of the PCM in the solver model. To determine the thermal stability of electronic equipment, we paid special attention to finding a thermal design for the PCM using fins. Further, an additional numerical analysis is currently underway to find an optimum design.

• Journal of Power Electronics
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• v.5 no.3
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• pp.233-239
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• 2005

In this paper, a new conceptual circuit configuration of a 3-phase voltage source, soft switching AC-DC-AC converter using an IGBT module, which has one ARCPL circuit and one ARDCL circuit, is presented. In actuality, the ARCPL circuit is applied in the 3-phase voltage source rectifier side, and the ARDCL circuit is in the inverter side. And more, each power semiconductor device has a novel clamp snubber circuit, which can save the power semiconductor device from voltage and current across each power device. The proposed soft switching circuits have only two active power semiconductor devices. These ARCPL and ARDCL circuits consist of fewer parts than the conventional soft switching circuit. Furthermore, the proposed 3-phase voltage source soft switching AC-DC-AC power conversion system needs no additional sensor for complete soft switching as compared with the conventional 3-phase voltage source AC-DC-AC power conversion system. In addition to this, these soft switching circuits operate only once in one sampling term. Therefore, the power conversion efficiency of the proposed AC-DC-AC converter system will get higher than a conventional soft switching converter system because of the reduced ARCPL and ARDCL circuit losses. The operation timing and terms for ARDCL and ARCPL circuits are calculated and controlled by the smoothing DC capacitor voltage and the output AC current. Using this control, the loss of the soft switching circuits are reduced owing to reduced resonant inductor current in ARCPL and ARDCL circuits as compared with the conventional controlled soft switching power conversion system. The operating performances of proposed soft switching AC-DC-AC converter treated here are evaluated on the basis of experimental results in a 50kVA setup in this paper. As a result of experiment on the 50kVA system, it was confirmed that the proposed circuit could reduce conduction noise below 10 MHz and improve the conversion efficiency from 88. 5% to 90.5%, when compared with the hard switching circuit.

• Archives of design research
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• v.17 no.3
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• pp.147-156
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• 2004

Currently, usability tests for web sites with representative users are conducted in laboratory environment that disturbs subjects' natural behavior. These test methods are inefficient for tests that require large number of subjects, because experimenters and subjects should be located in the same place at the same time during the test. In this study, a remote usability test tool, called 'RIO' has been developed to cope with these laboratory-based experiment problems - the 'synchronism' and the 'unnatural environment'. The tool is separated into three parts: 'Project Manager', 'Remote Interaction Observer', and 'Interaction Analyzer'. 'Project Manager' sets up overall experimental parameters and actual tasks to be peformed by subjects. 'Remote Interaction Observer', endued with Microsoft Internet Explorer Control, is a modified Web Browser which records user interactions, screen images and elaborate browser events while subject performs given tasks. This module is distributed to subjects as an installable software package. When they finish all the tasks, the captured interaction data is compressed and sent to 'Interaction Data Server' automatically. 'Interaction Analyzer' visualizes interaction data from the 'Interaction Data Server'. It also generates project-scope statistics which facilitate discovering peculiar cases among interaction submissions.

• Smart Media Journal
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• v.6 no.3
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• pp.41-48
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• 2017

Event detection using social media has been widespread since social network services have been an active communication channel for connecting with others, diffusing news message. Especially, the real-time characteristic of social media has created the opportunity for supporting for real-time applications/systems. Social network such as Twitter is the potential data source to explore useful information by mining messages posted by the user community. This paper proposed a novel system for temporal event detection by analyzing social data. As a result, this information can be used by first responders, decision makers, or news agents to gain insight of the situation. The proposed approach takes advantages of deep learning methods that play core techniques on the main tasks including informative data identifying from a noisy environment and temporal event detection. The former is the responsibility of Convolutional Neural Network model trained from labeled Twitter data. The latter is for event detection supported by Recurrent Neural Network module. We demonstrated our approach and experimental results on the case study of earthquake situations. Our system is more adaptive than other systems used traditional methods since deep learning enables to extract the features of data without spending lots of time constructing feature by hand. This benefit makes our approach adaptive to extend to a new context of practice. Moreover, the proposed system promised to respond to acceptable delay within several minutes that will helpful mean for supporting news channel agents or belief plan in case of disaster events.

• Nuclear Engineering and Technology
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• v.31 no.5
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• pp.506-511
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• 1999

The pilot system for radioactive liquid laundry waste was developed with treatment capacity, 1ton/hr and set up in the Yong Kwang unit #4. The system is composed of tank module, RO systems and a UV/$H_2O$$_2$photo-oxidation unit. The RO system consists of the BW unit (low-pressure RO for brackish water desalination) and the SW unit (high-pressure RO for seawater desalination). The BW unit possesses 4 RO membranes and it can reduce the feed water volume down to 1/10. This concentrated feed water can be reduced again up to 1/10 in its volume in the SW unit composed of 4 RO membranes. The UV/$H_2O$$_2$ photo-oxidation process unit was used for the detergent degradation. The operation of the pilot system was carried out and verified in its capability through the continuous operation and concentration operation using the actual liquid waste from the power plant. The design criteria and data for industrialization were yielded. The efficiency of the UV/$H_2O$$_2$ photo-oxidation process and the optimum operational procedure were evaluated. The decontamination factors for radioactive cobalt and cesium were measured. This on-site test showed the experimental result in the DF$\geq$300 and volume reduction factor$\geq$100.

• Nuclear Engineering and Technology
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• v.43 no.6
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• pp.567-572
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• 2011

A sensitivity analysis of the methods used to evaluate the transport properties of a CdZnTe detector was performed using two different radiations (${\alpha}$ particle and gamma-ray) emitted from an $^{241}Am$ source. The mobility-lifetime products of the electron-hole pair in a planar CZT detector ($5{\times}5{\times}2\;mm^3$) were determined by fitting the peak position as a function of biased voltage data to the Hecht equation. To verify the accuracy of these products derived from ${\alpha}$ particles and low-energy gamma-rays, an energy spectrum considering the transport property of the CZT detector was simulated through a combination of the deposited energy and the charge collection efficiency at a specific position. It was found that the shaping time of the amplifier module significantly affects the determination of the (${\mu}{\tau}$) products; the ${\alpha}$ particle method was stabilized with an increase in the shaping time and was less sensitive to this change compared to when the gamma-ray method was used. In the case of the simulated energy spectrum with transport properties evaluated by the ${\alpha}$ particle method, the peak position and tail were slightly different from the measured result, whereas the energy spectrum derived from the low-energy gamma-ray was in good agreement with the experimental results. From these results, it was confirmed that low-energy gamma-rays are more useful when seeking to obtain the transport properties of carriers than ${\alpha}$ particles because the methods that use gamma-rays are less influenced by the surface condition of the CZT detector. Furthermore, the analysis system employed in this study, which was configured by a combination of Monte Carlo simulation and the Hecht model, is expected to be highly applicable to the study of the characteristics of CZT detectors.

• The KIPS Transactions:PartB
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• v.17B no.3
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• pp.183-188
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• 2010

A factorization-based 3D reconstruction system is realized to recover 3D scene from an image sequence. The image sequence is captured from uncalibrated perspective camera from several views. Many matched feature points over all images are obtained by feature tracking method. Then, these data are supplied to the 3D reconstruction module to obtain the projective reconstruction. Projective reconstruction is converted to Euclidean reconstruction by enforcing several metric constraints. After many triangular meshes are obtained, realistic reconstruction of 3D models are finished by texture mapping. The developed system is implemented in C++, and Qt library is used to implement the system user interface. OpenGL graphics library is used to realize the texture mapping routine and the model visualization program. Experimental results using synthetic and real image data are included to demonstrate the effectiveness of the developed system.

• KIPS Transactions on Computer and Communication Systems
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• v.2 no.12
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• pp.553-560
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• 2013

The development of cloud computing technology and smart devices have increasingly been expanding the influence in various fields. Although DRM(Digital Rights Management) is a very important technology for secure content services, interoperability among DRM technologies must be addressed in order to provide the service without the constraints of time and place on various smart devices. In this paper, we study DRM Cloud which provides DRM functions as a service in cloud computing environment, and address interoperability problem by providing different DRM technologies as a cloud service. That is, when a user wants to play contents with the different DRM technologies on a smart device, the usage of the content is controlled by providing the corresponding DRM module and function as SaaS from DRM cloud. To do this, we define the functions and structure of DRM Proxy which performs smooth service call and provision between DRM cloud user and DRM cloud, and finally we describe the experimental implementation result.