• Transactions of the Korean hydrogen and new energy society
• /
• v.16 no.3
• /
• pp.244-252
• /
• 2005

It is very interesting and important in the academic point of view and in practical use the hydrogen-induced phase separation(HIPS) which appears during hydrogen heat treatment. Since hydrogen can be removed very fast by pumping it out the hydrogen-induced new lattice phase which can not be obtained without hydrogen can be preserved as meta-stable state. In this study it has been investigated whether the HIPS appear in Pd-Al, Pd-Co, Pd-Cr, Pd-Ti, Pd-V and Pd-Zr alloys and discussed thermodynamic representation of the HIPS. The Pd alloys were arc-melted under argon atmosphere and remelted 4 or 5 times for homogenization. The alloys were annealed at 600$^{\circ}C$ under vacuum for 24 hrs and then subjected to pressure-composition isotherm measurements at 100$^{\circ}C$. The hydrogen heat treatment(HHT) of samples was carried out at 600$^{\circ}C$ under hydrogen pressure of 70 bar for 6 days and PC isotherms at 100$^{\circ}C$ were measured. By comparing the PC isotherms measured before and after HHT, occurrence of phase separation was determined. The experimental results showed that the HIPS appeared only in Pd-0.05Co alloy. For Pd-Co alloys with various composition the PC isotherms were measured. By adopting Park-Flanagan model for ternary thermodynamics the Gibbs free energy change for Pd-Co-H solid solution was calculated and subsequently with this the HIPS in Pd-Co alloy was explained fairly.

• Aerospace Engineering and Technology
• /
• v.13 no.2
• /
• pp.80-86
• /
• 2014

In this study, we the estimated surface normalized difference vegetation index by using the KOrea Multi-Purpose SATellite-3 (KOMPSAT-3) multi-spectral images for comparative analysis. The estimated NDVI from KOMPSAT-3 is used as for comparison with the high resolution GeoEye products. The geometry conditions for atmospheric effects are selected from meta files of KOMPSAT-3 bundle data. The used geometry conditions are consist of solar zenith angle, solar azimuth angle, viewing zenith angle, viewing azimuth angle, and date. And, Atmospheric effects such as attenuation, scattering and absorption were physically simulated from water vapor, ozone and aerosol information. Generally, although ground measurements are important for accurate information, in this study, MODIS atmospheric products are used as atmospheric constituents. The surface reflectance from radiative transfer model is utilized for estimating vegetation index. The present study, to reduce atmospheric and geometry conditions between KOMPSAT-3 and GeoEye having difference observation characteristics, data acquisition time is carefully determined for reliable vegetation spectral characteristics.

• Journal of the Korea Society of Computer and Information
• /
• v.9 no.3
• /
• pp.115-120
• /
• 2004

As a part of working on development of the learning management system, a adaptive learning management system which is able to provide individual learner with different learning contents or paths customized to learner's learning behaviors by expanding SCORM was proposed in this dissertation. In terms of instructional technology interrelated with technology of CBI and ITS, new learning environments and learner preferences were analyzed. A related laboratory system was implemented by packaging a process on how to expand the meta data for contents and a process on how to utilize the web-based learning contents dynamically. In order to evaluate the usability of the implemented system, a sample content was provided to some selected learners and their learning achievement resulted from the new learning environment was analysed. A result of the experiment indicated that the adaptive learning management system proposed in this dissertation could provide every learner with the different content tailored to their individual learning preference and behavior. and it worked also to promote the learning performance of every learner.

• The Journal of the Korea Contents Association
• /
• v.9 no.12
• /
• pp.932-939
• /
• 2009

This paper implements the graphic service template authoring tool based on the service template object model of describing the meta information of the services for early childhood education in the semantic web service environment. Our proposed system provides the robot services by constructing web services automatically and making the appropriate service plans. Moreover, it can create, append, delete, and update the service templates of URC based on STDL, and provide the graphic function on service template resources. In order to provide the user friendly environment in the service template phase, we implement the various editing environment : flow view style, grid view style, and text view style. We also provide the easy editing function by realizing abstract service block based on the robot API. Finally we can offer the intelligent and autonomous service of service agent based on semantic information.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.33 no.6
• /
• pp.607-613
• /
• 2009

In this paper, we made a simple paper feeding system which is one of MTS (media transport system) and controllers. The plant has a flexible paper and two driving rollers and two driven rollers. The control system has two conventional PID controllers. Skew angle and feeding speed of MTS deteriorate the quality of feeding system. In order to control a feeding speed and skew of feeding paper, we control rotational velocity of two driving rollers. Therefore, this controller has two inputs and two outputs as MIMO (multi-input and multi-output) system. The control inputs were the feeding speed and the skew displacement of the paper. The control outputs were the rotational velocity to each driving roller. To find appropriate PID gains of two controllers, we proposed an optimization technique. We assume the system variables and performance of a whole system as follows. PID gains of two controllers for skew and feeding speed are system variables. System performance is both skew and feeding speed. We simulates to making mathematical correlation using global Kriging interpolation. To find appropriate value of system variables, optimization method is simulation in sequence as following method. First, the optimization solver simulates with DOE (design of experiment) tables to find correlation equation of both system variable and performances. Then, the solver guesses the appropriate values and simulates if the system variables are appropriate or not. If the result of validation doesn't satisfy the convergence and iteration tolerance, the solver makes a new Kriging models and iterates this sequence until satisfy the tolerances.

• Journal of the Korean School Mathematics Society
• /
• v.17 no.1
• /
• pp.23-43
• /
• 2014

This study aims to develop strategies for improving the affective characteristics of Korean students based on results from international achievement tests. In pursuing the goal, different research methods are employed including a) analysis of the theories and literature regarding the affective domains included in PISA and TIMSS studies; b) analysis of the current situation and needs of Korean students with respect to the affective factors based on PISA and TIMSS results; c) case studies of best practices in relation to students' affective domains in Korea and abroad; and d) development of strategies for improving and supporting Korean students' affective characteristics. Especially, this paper describes meta-analyses of the results from the previous PISA and TIMSS studies. Afterwards, it reports statistical analyses results on the relationship between students' affective achievements and educational context variables. Data from TIMSS 2011, TIMSS 2007, PISA 2006, and PISA 2003 are used for the analyses, and contextual variables are selected through rigorous statistical analyses including frequency and correlation, and expert consultation. The effects of educational contextual variables on students' affective achievement in mathematics and science are analyzed through Hierarchical Linear Model.

• Journal of Korean Neurosurgical Society
• /
• v.61 no.4
• /
• pp.467-473
• /
• 2018

Objective : The aim of this study was to determine outcome of ischemic stroke patients in the anterior circulation treated with endovascular treatment (EVT) with intravenous thrombolysis (IVT) versus EVT alone group. Methods : A systemic literature review was performed using online database from January 2004 to January 2017. Primary outcomes were successful recanalization seen on finial angiography and good outcome at three months. Secondary outcomes were mortality and the development of symptomatic intracranial hemorrhage (S-ICH) after the procedure. A fixed effect model was used when heterogeneity was less than 50%. Egger's regression test was used to assess publication bias. Results : Five studies were included for final analysis. Between EVT with IVT and EVT alone group, successful recanalization (odds ratio [OR] 1.467, p=0.216), good clinical outcome at three months (OR 1.199, p=0.385), mortality (OR 0.776, p=0.371), and S-ICH (OR 1.820, p=0.280) did not differ significantly. Egger's regression intercept with 95% confidence interval (CI) was 1.99 (95% CI -2.91 to 6.89) in successful recanalization and -0.27 (95% CI -6.35 to 5.80) in good clinical outcome, respectively. Conclusion : The two treatment modalities, EVT with IVT and EVT alone, could be comparable in treating acute anterior circulation stroke. Studies to find specific beneficiary group for EVT alone, without primary IVT, are needed further.

• Journal of KIISE:Software and Applications
• /
• v.31 no.1
• /
• pp.43-53
• /
• 2004

Component-based development(CBD) has acquired a substantial acceptance in both academia and industry as an effective inter-organizational reuse technology. A component framework in product line engineering(PLE) which consists of related components, connectors and their semantics has a greater potential for reusability than components. In frameworks, components are glued with association, dependency and connections. Problems occur like affecting the implementation code of components when they are glued and replaced because the association and dependency relationships between COTS components which are acquired for application development do not match exactly. Especially, a connector may not only connect related components, but also mate partially-matched COTS components fit together. However, little has been studied to date about connectors that can be used practically. In this paper, we present a meta-model for connectors and show how a connector can be designed and implemented in practice. We propose five main patterns of connectors. Proposed major patterns Provide design guidelines for practical and efficient connector configuration based on component framework. And also, applying techniques and applied case studies of the major patterns show greatly increased applicability and reusability of the component without component modification.

• Journal of KIISE:Databases
• /
• v.33 no.7
• /
• pp.741-753
• /
• 2006

As the total amount of traffic data in network has been growing at an alarming rate, many researches to mine traffic data with the purpose of getting useful information are currently being performed. However, network users' privacy can be compromised during the mining process. In this paper, we propose an efficient and practical privacy preserving sequential pattern mining method on network traffic data. In order to discover frequent sequential patterns without violating privacy, our method uses the N-repository server model and the retention replacement technique. In addition, our method accelerates the overall mining process by maintaining the meta tables so as to quickly determine whether candidate patterns have ever occurred. The various experiments with real network traffic data revealed tile efficiency of the proposed method.

• Journal of the Korean Operations Research and Management Science Society
• /
• v.41 no.3
• /
• pp.75-96
• /
• 2016

This paper investigates the usefulness of drones in an urban delivery system. We define the vehicle and drone routing problem with time window (VDRPTW) and present a model that can describe a dual mode delivery system consisting of drones and vehicles in the metropolitan area. Drones are relatively free from traffic congestion but have limited flight range and capacity. Vehicles are not free from traffic congestion, and the complexity of urban road network reduces the efficiency of vehicles. Using drones and vehicles together can reduce inefficiency of the urban delivery system because of their complementary cooperation. In this paper, we assume that drones operate in a point-to-point manner between the depot and customers, and that customers in the need of fast delivery are willing to pay additional charges. For the experiment datasets, we use instances of Solomon (1987), which are well known in the Vehicle Routing Problem society. Moreover, to mirror the urban logistics demand trend, customers who want fast delivery are added to the Solomon's instances. We propose a hybrid evolutionary algorithm for solving VDRPTW. The experiment results provide different useful insights according to the geographical distributions of customers. In the instances where customers are randomly located and in instances where some customers are randomly located while others form some clusters, the dual mode delivery system displays lower total cost and higher customer satisfaction. In instances with clustered customers, the dual mode delivery system exhibits narrow competition for the total cost with the delivery system that uses only vehicles. In this case, using drones and vehicles together can reduce the level of dissatisfaction of customers who take their cargo over the time-window. From the view point of strategic flexibility, the dual mode delivery system appears to be more interesting. In meeting the objective of maximizing customer satisfaction, the use of drones and vehicles incurs less cost and requires fewer resources.