• Proceedings of the KSRS Conference
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• 2007.10a
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• pp.153-155
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• 2007

Korea Meteorological Administration (KMA) has operationally produced Atmospheric Motion Vector (AMV) from the consecutive MTSAT-1R satellite image dataset. Comparing with radiosonde data, our current AMV scheme shows more than 10 m/s RMSE. Therefore we need to improve continuously its accuracy. Many AMV producers have stated that the bad performance of the Height Assignment (HA) algorithm is the main reason of degrading the accuracy of AMV. The uncertainties in AMV HA can occur in the algorithm itself, used NWP profiles, and the performance of Radiative Transfer Model (RTM) etc. This study introduces currently operated AMV HA schemes and the impacts of NWP profile data and RTM that these schemes use were investigated. Finally we analyzed the relationship between vectors by vector tracking and heights assigned to each vector by using collocated wind profile dataset with radiosonde data. This study is a preliminary work to improve the accuracy of AMV by removing or decreasing the uncertainties in AMV estimation.

• Journal of Korean Society of Transportation
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• v.27 no.6
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• pp.167-176
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• 2009

Several travel demand management schemes have been used for controlling overloaded traffics on urban area. To maximize efficiency of the travel management, traffic manager has to set target level that we try to arrive in advance, and then to find optimal variable to attain this goal. In this regard, this paper presents two travel demand management models, expressed by mathematical program, and also presents their solution algorithms. The first is to find optimal travel demand for origin-destination (OD) pair, based on average travel time between the OD pair, and the second is based on the ratio of volume over capacity on congested area. An example is given to test the models.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.24 no.12A
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• pp.1868-1875
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• 1999

The design of LAI(Local Area Identifier), the first paging area for searching the mobile terminal has a close relation with the performance of paging channel in CDMA cellular network. This paper discussed the performance of the forward channel of IS-95 CDMA standard, known as the paging through the related messages such as call control message, channel assignment message, etc. Modeling and simulation work were conducted to quantify the performance of paging channel in terms of traffic handling capacity and blocking levels. The results shown are based on a specific system call model based on the operating system of cell cite. This serves as illustrative guidelines for the proper engineering of common control channel, which has a major impact on the overall performance of cellular network.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.7 no.12
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• pp.3037-3054
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• 2013

Interference between primary user (PU) and secondary user (SU) transceivers should be mitigated in order to implement underlay spectrum sharing in cognitive radio networks (CRN). Considering this scenario, an improved joint subcarrier and bit allocation scheme for cognitive user with primary users' cooperation (PU Coop) in CRN is proposed. In this scheme, the optimization problem is formulated to minimize the average interference power level at the PU receiver via PU Coop, which guarantees a higher primary signal to interference plus noise ratio (SINR) while maintaining the secondary user total rate constraint. The joint optimal scheme is separated into subcarrier allocation and bit assignment in each subcarrier via arith-metric geo-metric (AM-GM) inequality with asymptotical optimization solution. Moreover, the joint subcarrier and bit optimization scheme, which is evaluated by the available SU subcarriers and the allocated bits, is analyzed in the proposed PU Coop model. The performance of cognitive spectral efficiency and the average interference power level are investigated. Numerical analysis indicates that the SU's spectral efficiency increases significantly compared with the PU non-cooperation scenario. Moreover, the interference power level decreases dramatically for the proposed scheme compared with the traditional Hughes-Hartogs bit allocation scheme.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.39 no.9
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• pp.997-1005
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• 1990

Integral Error and State Feedback (IESF) controller which incorporates state feedback as a modern control scheme and integral action as a classical control scheme has better performance than that of conventional PID controller in linear time invariant system. But the structure of the IESF controller requires all the state variables of the system and is applicable only to pole assignable linear time invariant systems without time delay. Many industrial processes have large time delay and it is impossible to directly apply IESF control scheme to those processes. In this paper, a new controller structure, Modified Integral Error and State Feedback (MIESF) has been suggested in order to effectively control processes having time delay and its performance has been analyzed and its effectiveness has also been confirmed. As the proposed controller uses output feedback scheme based on integral error and state feedback (IESF) method, it can be simply designed by pole assignment algorithm irrespective of the order of the process. The MIESF controller can follow setpoint changes without overshoot. It is robuster than conventional Smith-Predictor plus PI(D) controller in case of occurring time delay mismatch and extra parameter mismatches between the process and the model. It can enhance control performance by intentional time delay mismatch.

• Spatial Information Research
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• v.5 no.2
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• pp.177-183
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• 1997

S1he concept of a class in the land-use classification system can be equally applied to a class in the land-use-change classification. The maximum likelihood method using linear discriminant function and Markov transition matrix method were integrated to a synthetic modeling effort in order to project spatial allocation of land-use-change and quantitative assignment of that prediction as a whole. The algorithm of both the multivariate discriminant function and the Markov chain matrix were discussed and the test of synthetic model on the study area was resulted in the projection of '90 year as well as '95 year land -use classification. The accuracy and the issue of modeling improvement were discussed eventually.

• Journal of The Korean Association of Information Education
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• v.16 no.1
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• pp.33-40
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• 2012

The purpose of this study is to find the relationship of academic self-efficacy, motivation, computer learning attitudes on the learning through game making activity. Through this study, it was confirmed structural relationship of the variables for learner's participant and academic goal achievement in learning with digital games. The structural equating model in this study, also indicates that academic self-efficacy, which was consisting of assignment level, self-efficacy, confidence affects meaningfully on motivation and computer learning attitudes. It is important factor that Learner's attitudes for the task and regulate of learning process in learning with digital games, which was focused on learning by doing.

• International Commerce and Information Review
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• v.6 no.1
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• pp.99-126
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• 2004

E-Trade is expected to dominate the global trade in the 21st century and thus is being introduced as a major policy assignment for each development country. e-trade has the potential to accelerate existing trends and introduce new ways of conducting trade. and e-trade is an alternative to strengthen international competitiveness. therefore, we needs to quickly adjust to this new method of e-trade and provide a number of policy suggestions that it can make best use of. However, successful implemetation, diffusion and usage of e-trade system require cooperation, commitment and the trust of all participating members in international trade process. A number of interorganizational, intraorganizational and innovation factors can influence both the extent to which e-trade is diffused and the level of subsequent performance that accure to participating firms. Considering the characteristics of e-trade, the proposed factors are based on an interdisciplinary study. The research model is based on the theories of innovation diffusion, inter-organizational system, and IS implementation. The factors proposed for this study of external firm factors, internal firm and perception factors.

• The Journal of Korean Association of Computer Education
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• v.5 no.1
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• pp.67-73
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• 2002

This paper describes the web-based collaborative learning system, in which the constructivism is used as a background theory. We designed and developed three modules (Learner Module, Instructor Module, Administrative Module) to promote the interactive communication between learners and instructors and to enable the self-directed collaborative learning. In addition, the assignment and evaluation sessions are closely linked with each other to ensure the high quality of the system. We expect this research helps to construct the efficient collaborative learning environment using the ICT(Information & Communication Technology).

• Proceedings of the Korean Institute Of Construction Engineering and Management
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• 2007.11a
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• pp.531-534
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• 2007

In the current domestic design-build contract, design and construction are separated due to prohibition of outside work. but instead the design-build contract adopts a method of fulfilling each assignment as a joint venture, which makes it difficult for participants to communicate each other and often require changes of design. also, It is difficult to performance efficiency project that they don't want to share useful information related to design and construction. In this study suggests how to maxmize the effiency of the project by proposing a process model connected with an efficient partnering and constructability in a deign development phase of design-build constract.