• The Journal of Korean Institute of Communications and Information Sciences
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• v.41 no.8
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• pp.965-973
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• 2016

As increase of IoT services in wireless communications, the performance evaluation is required to connects massive number of devices in LTE-A system. Existing performance analysis of 3GPP TR 37.868 is shown the limited results up to the number of devices only 30,000 in a cell. So, it is required the performance analysis according to various parameter values in the greater number of devices environment. In this paper, to evaluate the performance, we developed the new modules to simulate LTE-A random access procedures because of a limit that accommodate massive number of devices in existing LTE module. The simulator was developed by OPNET and it can support up to 100,000 devices per cell. This paper also represents the performance analysis results according to the number of preambles, the maximum number of preamble transmissions, backoff indicator and msg2 window size in the same environment with 3GPP TR 37.868. This results are expected to be utilized such as the transition to 5G network and standardization activities.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.17 no.4
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• pp.57-67
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• 2014

The vigor condition of trees is an important indicator for the management of urban forested area. But difficulties in how to assess the tree vigor condition still remain. Previous efforts were limited in the 1) measurement of single indicator rather than using multiple indices, 2) purpose-oriented measurement such as for air-pollution effect or specific pathological symptom, and 3) ordinal-scale evaluations by field crews 4) despite human errors based on his/her experiences or prior knowledge. Therefore, this study attempted to develop a quantitative and objective methodology for assessing tree vigor condition, by measuring multiple modules and building the profile inventory. Furthermore, the possibility and limitations were discussed in terms of schematic frames describing tree vigor condition. The vigor condition of 56 flowering cherry plants in urban park were assessed by in-situ measurements of following eight items; growth of crown(Gc), growth of shoots, individual tree volume(Vol), plant area index, woody area index, leaf area index, leaf chlorophyll content(Lc) and leaf water content(Lw). For validation, these measurements were compared with the ranks of holistic tree vigor condition, which were visually assessed using a 4-point grading scale based on the expert's knowledge. As a result, the measures of each evaluation item successfully highlighted a variety of aspects in tree vigor condition, including the states of both photosynthetic and non-photosynthetic parts. The variation in the results depending on evaluated parts was shown within an individual tree, even though the broad agreement among the results was found. The result of correlation analysis between the tested measurements and 4-point visual assessment, demonstrated that the state of water-stressed foliage of the season (Lw) or the development of plant materials since sapling phase (Vol) could be better viewed from the outer appearance of trees than other symptoms. But only based on the visual assessment, it may be difficult to detect the quality of photosynthesis (Lc) or the recent trend in growth of trees (Gc). To make this methodology simplified for the broad-scale application, the tested eight measurements could be integrated into two components by principal component analysis, which was labelled with 'the amount of plant materials' and 'vigor trend', respectively. In addition, the use of these quantitative and multi-scale indicators underlies the importance of assessing various aspects of tree vigor condition, taking into account the response(s) on different time and spatial scale of pressure(s) shown in each evaluated module. Future study should be advanced for various species at diverse developing stages and environment, and the application to wide areas at a periodic manner.

• Archives of design research
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• v.12 no.3
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• pp.227-234
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• 1999

We paid attention to the fact that a project will always tend to increase in size even if its scope is narrowing. The complexities and multidisciplinary aspects of projects require that the many parts should be put together so that the prime objectives- performance, time, and cost- are met. These aspects lead to the use of teams to solve problems that used to be solved by individuals. Firstly, We surveyed the design companies and their clients on the design projects, and categorized the design task into 5 phases, that are marketing, planning, idea development, presentation, and follow-up. Among the phases, the presentation has the most difficult task, longest processing time, and highest cost, whereas idea development phase has relatively low cost, longer processing time, and more difficult task. Most of the companies used to be faced several bottlenecks on their design projects - time control, budget control, and resource control. Secondly, for improving the project managing process, we adopted that dividing and analyzing the sub critical paths may help in the effective managing.(Badiru, Adedeji B., 1995) Some critical paths require almost as much attention as the critical path since they have a high potential of becoming critical when changes occur in the network. Therefrom we suggest the Total task weight(Gt) as a management formula for the design project management.${Gt=\mathrm{T}\ast\leftthreetimes\ast1/100}$<\TEX> ( Gt = Total task weight, mathrm{T} = Task Weight, \leftthreetimes= Criticality ) Thirdly, In order to support to managing for the design projects, we set up an application system, which is graphically planning and implementing a complex undertaking. It is helpful to make the control of a project easy. The DPMS(Design Project Management System), which has two sub system. One is Project Screening System(PSS), and another Project Managing System(PMS). In PMS, we divided the design project into three modules; Project Planning, Project Implementation, and Project Evaluation. As a result, the DPMS will contribute to supply the control of a project easily and effectively. Also teams are used for making decisions and taking action with the DPMS. But we need to get further studies on the relationships between the whole project and its tasks.

• Journal of KIISE:Software and Applications
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• v.31 no.3
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• pp.255-266
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• 2004

In the Web-based information systems, separating the business process logic from the data and presentation logic brings about a wide range of advantages. However, this separation is not easily achieved; even the data logic may be not separated from the presentation layer. So, it requires to define an model for business processes, and then to map the model into the user's dynamic interface using the logic separating strategy. This paper presents a stylesheet method to recognize the process by extending XSLT (Extensible Stylesheet Language Transformations), in order to achieve the logic separation. To do this, it provides an specification of the business process, and a scheme that extracts business model factors and their interactions using a Petri-net notation to show the business model into the process point of view. This is an attempt to separate users' interaction from the business process, that is, dynamic components of interaction Web document from the process structure of Web applications. Our architecture consist mainly of an XSLT controller that is extended by a process control component. The XSLT controller is responsible for receiving the user requests and searching the relevant templet rule related to different user requests one by one. Separation of concerns facilities the development of service-oriented Web sites by making if modular. As a result, the development of service-oriented Web sites would be very easy, and can be changed without affecting the other modules, by virtue of the modularization concept. So, it is easy to develop and maintain the Web applications in independent manner.

• Journal of KIISE:Computer Systems and Theory
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• v.32 no.2
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• pp.75-84
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• 2005

This research is to design a high performance NAND-type flash memory package with a smart buffer cache that enhances the exploitation of spatial and temporal locality. The proposed buffer structure in a NAND flash memory package, called as a smart buffer cache, consists of three parts, i.e., a fully-associative victim buffer with a small block size, a fully-associative spatial buffer with a large block size, and a dynamic fetching unit. This new NAND-type flash memory package can achieve dramatically high performance and low power consumption comparing with any conventional NAND-type flash memory. Our results show that the NAND flash memory package with a smart buffer cache can reduce the miss ratio by around 70% and the average memory access time by around 67%, over the conventional NAND flash memory configuration. Also, the average miss ratio and average memory access time of the package module with smart buffer for a given buffer space (e.g., 3KB) can achieve better performance than package modules with a conventional direct-mapped buffer with eight times(e.g., 32KB) as much space and a fully-associative configuration with twice as much space(e.g., 8KB)

• Journal of the Korean Electrochemical Society
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• v.4 no.4
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• pp.152-159
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• 2001

Electric vehicle performance is very dependent on traction batteries. For developing the electric vehicles with high performance and good reliability, the traction batteries have to be managed to get maximum performance under various operating conditions. The enhancement of the battery performance can be accomplished by implementing battery management system (BMS) that plays important roles of optimizing the control mechanism of charge and discharge of the batteries as well as monitoring battery status. In this study the battery management system has been developed for maximizing the use of Ni/MH batteries in electric vehicle. This system provides several tasks: the control of charging and discharging, overcharge and over-discharge protection, the calculation and display of state of charge, safety and thermal management. The BMS was installed in and tested using the DEV5-5 electric vehicle developed by Daewoo Motor Co. and Institute for Advanced Engineering in Korea. The 18 modules of Panasonic Ni/MH battery, 12 V-95 Ah, were used in the DEV5-5. The high accuracy within the range of $3\%$ and the good reliability were shown in the test results. The BMS can also improve the performance and cycle life of Ni/MH battery pack as well as the reliability and safety of the electric vehicles (EV).

• Journal of Korea Spatial Information System Society
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• v.6 no.1 s.11
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• pp.31-50
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• 2004

With the growth of wireless communication networks and mobile devices taking in GPS, Location-Based Service(LBS) is becoming an integral part of mobile applications. LBS can deal with location-aware features such as persons holding mobile phones or vehicles equipped with GPS, and provide the users with the location information of the features. Thus it is necessary to develop moving object database systems to store, manage, and query moving objects which change their locations continuously as time passes. In this paper, we design and implement a query processing component which deals with moving objects as a key data type. For this component, we define a new SQL-like query language(called MOQL) and as a consequence, design and implement modules that analyze and execute queries. It supports various types of operators that process range queries, infer topological relations, compute trajectories, and find k-nearest neighbors. It can be used as a subsystem if other application systems which deal moving objects and also supports ADO.NET interface that can be used to interact end-users.

• Journal of the Microelectronics and Packaging Society
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• v.15 no.3
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• pp.53-58
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• 2008

In this study, we fabricated embedded IC (Double Pole Double throw switch chip) polymer substrate and evaluate it for 2.4 GHz WiFi application. The switch chips were laminated using FR4 and ABF(Ajinomoto build up film) as dielectric layer. The embedded DPDT chip substrate were interconnected by laser via and Cu pattern plating process. DSC(Differenntial Scanning Calorimetry) analysis and SEM image was employed to calculate the amount of curing and examine surface roughness for optimization of chip embedding process. ABF showed maximum peel strength with Cu layer when the procuring was $80\sim90%$ completed and DPDT chip was laminated in a polymer substrate without void. An embedded chip substrate and wire-bonded chip on substrate were designed and fabricated. The characteristics of two modules were measured by s-parameters (S11; return loss and S21; insertion loss). Insertion loss is less than 0.55 dB in two presented embedded chip board and wire-bonded chip board. Return loss of an embedded chip board is better than 25 dB up to 6 GHz frequency range, whereas return loss of wire-bonding chip board is worse than 20 dB above 2.4 GHz frequency.

• Journal of the Korean Society of Hazard Mitigation
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• v.8 no.5
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• pp.119-128
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• 2008

Sewer rehabilitation is performed to improve the problem for urban drainage sewer system recently. However the data for the sewer system is not stored enough so that the sewer system is difficult to be managed systematically. In this study, a maintenance management system for urban drainage system is developed to store the data efficiently and manage the system systematically. In the developed system, a hydraulic and hydrologic analysis module is included to test the carrying capacity of a sewer pipe and estimate the amount of combined sewer overflows. The I/I and superannuation evaluation module is included in this system. The module distribute the total inflow/infiltration observed at the several sampling points in a drainage area to the individual pipes of the entire sewer system. Then the superannuation of a sewer pipe is evaluated according to the amount of I/I of the pipe. And in the developed system, the optimal rehabilitation priority module is included to determine the optimal priority and support the decision making for the sewer rehabilitation. The maintenance management system which is developed in this study is constructed by the association with the developed modules and the system is formed as graphical user interface system.

• Journal of Engineering Education Research
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• v.9 no.4
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• pp.28-45
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• 2006

As society has changed to being more knowledge-based, it is indispensable that Internet usage is incorporated into education. Therefore, the e-learning system is being developed in order to provide a proper environment. However, many LCMS that were developed, currently are not based on SCORM, the world e-learning standard, nor KEM, the Korea Educational Metadata of Korea Education & Research Information Service(KERIS), and hence, it is difficult to share learning contents developed from such varied environments. National Science Museum, a non-educational institution, also provides the educational science exhibits in reality or in cyber space, which cannot be produced by elementary schools, and secondary schools. Consequently, new systems are necessary, whose modules should be divided into four, for example, 'teachers', 'learners', 'managers', and 'instructors', and be associated with each other so that they are able to integrate and manage such systems, and be used in school education as well. Therefore, in this study, more advanced LMS and LCMS, which are the web-portal sites used for a cyber science class at the National Science Museum, were designed and established. These sites were surely based on the KEM, and the SCORM.