• Journal of the Korean GEO-environmental Society
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• v.20 no.1
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• pp.67-74
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• 2019

Frost heave is one of the representative engineering characteristics in cold regions. In South Korea, which is located in seasonal frost area, structural damage caused by frost heave and thaw happens and the need for research on the frost heave is increasing. In this paper, newly developed transparent temperature-controllable cell is used to focus on the frost heave. Frost susceptible artificial soil is used to analyze water intake rate which is one of the important factors in frost susceptibility criteria. Frost heave rate and water intake rate have similar behavior after heave by freezing of pore water converges. O-ring installed in the upper pedestal to measure water intake rate generates side friction between the inner wall of the freezing cell and O-ring, thereby hindering frost heave. Therefore, the frost susceptibility criteria using the water intake rate is not reliable. It is appropriate to use frost heave rate which has similar behavior with water intake rate. Frost heave tests were performed under two different specimen heights. Overburden pressure, temperature gradient and dry unit weight were set under similar state. Based on laboratory testing results, frost heave is independent on the specimen height.

• Journal of Advanced Marine Engineering and Technology
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• v.33 no.8
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• pp.1261-1267
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• 2009

The Direct Torque Control[DTC] controls torque and flux by restricting the flux and torque errors within respective hysteresis bands, and motor torque and flux are controlled by the stator voltage space vector using optimum inverter switching table. And the Current Error Compensation method is on the basis of compensating current difference between the induction motor and its numerical model, in which the identical stator voltage is supplied for both the actual motor and the model so that the gaps between stator currents of the two can be forced to decay to zero as time proceeds. Consequently, the rotor speed approaches to the model speed, namely, setting value and the system can control motor speed precisely. This paper proposes a new sensorless speed control of induction motor using DTC and Current Error Compensation, which requires neither shaft encoder, speed estimator nor PI controllers. And through computer simulation, confirm effectiveness of proposed method.

• Journal of Digital Convergence
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• v.13 no.8
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• pp.253-260
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• 2015

Because mass of activity records of individuals and organizations are accumulated in the digital space and amount of information is also increasing exponentially, the most urgent requirements of users is the tool for 'efficient' acquisition of 'useful' information. This paper try digital convergence to combine a domain specific technology with real time issue detection and grouping based on Web media. To derive core functionalities, we collect and analyze user requirements of national defense issue detection services. By utilizing linguistic resources specialized on national defence area and discovering features for measuring issue importance, we try to seek differentiation domain specific issue detection method. Finally we compare our detection results based on the development outputs of prototype.

• Ocean and Polar Research
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• v.36 no.4
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• pp.437-445
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• 2014

A time-series sediment trap was operated at a water depth of 4950 m from July 2003 to May 2004 at KOMO station ($10^{\circ}30^{\prime}N$, $131^{\circ}20^{\prime}W$) in the northeastern equatorial Pacific, with the aim of understanding the temporal variation of planktonic foraminifera assemblages in response to the seasonal shift of Inter-Tropical Convergence Zone (ITCZ). A total of 22130 planktonic foraminifera specimens belonging to 30 species and 11 genera were identified, which shows a distinct seasonal variation with high values (125~288 specimens $m^{-2}day^{-1}$) in the winter to spring (December-May) and low values (16~23 specimens $m^{-2}day^{-1}$) in the fall (September-November). In addition, seasonal ecological differences of foraminifera assemblages are distinctly recognizable: omnivorous foraminifera occurred predominantly during the summer season, whereas herbivorous ones were dominant during the winter season. Such seasonal variations correspond to the seasonal shift of the ITCZ. Enhanced occurrence of herbivorous species during the winter-spring season seems a result of surface water mixing generated by the southward shift of the ITCZ. The increase in omnivorous species during the summer season may be due to the northward movement of the ITCZ caused by weakened wind speed, resulting in the intensification of water column stratification and nutrient-poor environment. A significant reduction of planktonic foraminifera specimens during the fall is attributed to heavy precipitation and reduction in light intensity.

• Spatial Information Research
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• v.13 no.1 s.32
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• pp.103-117
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• 2005

Information can be visualized as information technology and computers have recently made dramatic improvements. Thanks to the brisk effects of providing information in 3D on the web with the technological developments of Web 3D and virtual reality implementation in the Internet, there has been the trend to present geographic information in images and 3D. In this study, the Web 3D GIS technique was adopted in analyzing the current state of urban landscape and examining and predicting the urban landscape affected by new urban development businesses. As a result, it was expected that the study would be able to help the government agencies to reduce their errors in making urban landscape plans and policies and implementing them to provide objective and visual data, and to come up with a simulation system that could be used to reflect the residents opinions in plans and policies.

• The Journal of the Korea Contents Association
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• v.9 no.3
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• pp.1-8
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• 2009

This paper proposes a new document clustering system using fuzzy logic-based genetic algorithm (GA) and semantic vector expansion technology. It has been known in many GA papers that the success depends on two factors, the diversity of the population and the capability to convergence. We use the fuzzy logic-based operators to adaptively adjust the influence between these two factors. In traditional document clustering, the most popular and straightforward approach to represent the document is vector space model (VSM). However, this approach not only leads to a high dimensional feature space, but also ignores the semantic relationships between some important words, which would affect the accuracy of clustering. In this paper we use latent semantic analysis (LSA)to expand the documents to corresponding semantic vectors conceptually, rather than the individual terms. Meanwhile, the sizes of the vectors can be reduced drastically. We test our clustering algorithm on 20 news groups and Reuter collection data sets. The results show that our method outperforms the conventional GA in various document representation environments.

• Journal of the Korea Society for Simulation
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• v.26 no.1
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• pp.1-11
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• 2017

During the past several years the ROK military has made an effort to build LVC synthetic battlefield that reflects the real world environment. In spite of its efforts, little has been accomplished. The disappointing achievement is mainly due to the lack of operational requirements and concepts, and policies or systematic approaches on the architecture and technology. Furthermore, there is insufficient understanding on the basic concepts and principles, and conflicting interests between organizations. In this study, I propose to construct an LVC based on the HLA that focuses on the system view and technical standard view, rather than the operational view. The proposed approach employs the information centric integration, focuses on an architecture convergence efforts based on the HLA/RTI, emphasizes the HLA compliance test and federation test, adapts to DSEEP, DMAO, and FEAT, and finally invents and implements an LVC Compliance Test System.

• The Journal of Korean Association of Computer Education
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• v.23 no.1
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• pp.1-28
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• 2020

The purpose of this study is to establish the standard curriculum for informatics by reflecting the changing information technology and social needs and based on the competencies that school at each level must have. To accomplish the purpose, the informatics curriculums of 8 countries were analyzed, and the learning elements of the curriculum were extracted with the body of knowledge of the higher-level informatics standard curriculum being the frame. To establish the standard curriculum, 51 experts reviewed it and their opinions were collected 10 times. As a result of this study, the competencies that need to be fostered through the informatics curriculum were defined, and the competency-centered curriculum, including the learning elements required to acquire the competencies, and the competencies that can be manifested through the learning element, was proposed. The implication is that the informatics standard curriculum, proposed in this study, laid down the foundation for establishing the informatics curriculum scheduled to be revised in 2022.

• Korean Security Journal
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• no.16
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• pp.283-304
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• 2008

The development of IT technology help citizens demand information and public services through internet that they want, and the changes also help the government converge public opinions and become important measures for citizens to participate in deciding governmental policies. So, this thesis makes an overture of a possibility for utilizing PCRM, a way for citizens to participate in Police Administration, by utilizing IT technologies in which everybody can participate without difficulty. The utilization ways are, on a large scale, classified with a macroscopic aspect and microscopic aspect. One of the macroscopic aspects is, first, the consideration of access to services and convenience in utilization. Second, services should have a both-sidedproperty. Ultimately, citizens'participation should have a positive mutual participation level. One of the microscopic aspects is, first, that the police organizations have to establish a strategy to analyze and fractionate customers. Second, the police organizations have to make an effort to develop policy services and P.R strategies. Third, police organizations have to make an effort to manage customers. Fourth, police organizations have to execute customer management in general. So, all of the police organizations have to maintain unity, to some extent, about citizen participation plazas. In addition, at the same time, consciousness aspects have to be accompanied for the reasonable utilization of PCRM. Citizens have to cultivate citizen consciousness, ownership consciousness for society, and positive participation consciousness to solve social problems.

• Journal of Korean Society of Transportation
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• v.26 no.4
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• pp.123-133
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• 2008

Information collection systems and applications in a ubiquitous environment has emerged as a leading issue in transportation and logistics. A productive application example is a traffic information collection system based on probe vehicles and wireless communication technology. Estimation of hourly OD pairs using probe OD data is a possible target. Since probe OD data consists of sample OD pairs, which vary over time and space, computation of sample rates of OD pairs and expansion of sample OD pairs into static OD pairs is required. In this paper, the authors proposed a method to estimate sample OD data with probe data in Jeju City and expand those into static OD data. Mean absolute percentage difference (MAPD) error between observed traffic volume and assigned traffic volume was about 22.9%. After removing abnormal data, MAPD error improved to 17.6%. Development of static OD estimation methods using probe vehicle data in a real environment is considered the main contribution of this paper.