• International Journal of Automotive Technology
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• v.8 no.3
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• pp.383-394
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• 2007

Due to the clutch's non-linear dynamics, time-delays, external disturbance and parameter uncertainty, the automated clutch is difficult to control precisely during the launch process or automatic mechanical transmission (AMT) vehicles. In this paper, an enhanced fuzzy sliding mode controller (EFSMC) is proposed to control the automated clutch. The sliding and global stability conditions are formulated and analyzed in terms of the Lyapunov full quadratic form. The chattering phenomenon is handled by using a saturation function to replace the pure sign function and fuzzy logic adaptation system in the control law. To meet the real-time requirement of the automated clutch, the region-wise linear technology s adopted to reduce the fuzzy rules of the EFSMC. The simulation results have shown hat the proposed controller can achieve a higher performance with minimum reaching time and smooth control actions. In addition, our data also show that the controller is effective and robust to the parametric variation and external disturbance.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2005.10a
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• pp.321-333
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• 2005

With the limited frequency spectrum and an increasing demand for cellular communication services, the problem of channel assignment becomes increasingly important. However, finding a conflict free channel assignment with the minimum channel span is NP hard. As demand for services has expanded in the cellular segment, sever innovations have been made in order to increase the utilization of bandwidth. The innovations are cellular concept, dynamic channel assignment and hierarchical network design. Hierarchical network design holds the public eye because of increasing demand and quality of service to mobile users. We consider the frequency assignment problem and the base station placement simultaneously. Our model takes the candidate locations emanating from this process and the cost of assigning a frequency, operating and maintaining equipment as an input. In addition, we know the avenue and demand as an assumption. We propose the network about the profit maximization. This study can apply to GSM(Global System for Mobile Communication) which has 70% portion in the world. Hierarchical network design using GA(Genetic Algorithm) is the first three-tier (Macro, Micro, Pico) model, We increase the reality through applying to EMC (Electromagnetic Compatibility Constraints). Computational experiments on 72 problem instances which have 15${\sim}$40 candidate locations demonstrate the computational viability of our procedure. The result of experiments increases the reality and covers more than 90% of the demand.

• Journal of Computing Science and Engineering
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• v.9 no.2
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• pp.98-107
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• 2015

Hierarchical constraints and constraint satisfaction were analyzed in order to solve the problem of conflict detection in collaborative design. The constraints were divided into two sets: one set consisted of known constraints and the other of unknown constraints. The constraints of the two sets were detected with corresponding methods. The set of the known constraints was detected using an interval propagation algorithm, a back propagation (BP) neural network was proposed to detect the set with the unknown constraints. An immune algorithm (IA) was utilized to optimize the weights and the thresholds of the BP neural network, and the steps were designed for the optimization process. The results of the simulation indicated that the BP neural network that was optimized by IA has a better performance in terms of convergent speed and global searching ability than a genetic algorithm. The constraints were described using the eXtensible Markup Language (XML) for computers to be able to automatically recognize and establish the constraint network. The implementation of the conflict detection system was designed based on constraint satisfaction. A wind planetary gear train is taken as an example of collaborative design with a conflict detection system.

• Journal of Positioning, Navigation, and Timing
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• v.8 no.4
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• pp.153-164
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• 2019

This paper presents the development of an end-to-end numerical simulator for signal design of the next generation global navigation satellite system (GNSS). The GNSS services are an essential element of modern human life, becoming a core part of national infra-structure. Several countries are developing or modernizing their own positioning and timing system as their demand, and South Korea is also planning to develop a Korean Positioning System (KPS) based on its own technology, with the aim of operation in 2034. The developed simulator consists of three main units such as a signal generator, a channel unit, and a receiver. The signal generator is constructed based on the actual navigation satellite payload model. For channels, a simple Gaussian channel and land mobile satellite (LMS) multipath channel environments are implemented. A software receiver approach based on a commercial GNSS receiver model is employed. Through the simulator proposed in this paper, it is possible to simulate the entire transceiver chain process from signal generation to receiver processing including channel effect. Finally, numerical simulation results for a simple example scenario is analyzed. The use of the numerical signal simulator in this paper will be ideally suited to design a new navigation signal for the upcoming KPS by reducing the research and development efforts, tremendously.

• IEMEK Journal of Embedded Systems and Applications
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• v.9 no.2
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• pp.87-99
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• 2014

An AUTomotive Open System ARchitecture (AUTOSAR) is a de-facto standardized software platform, which developed for an automotive Electronic Control Unit (ECU) in global automotive industry. AUTOSAR improves the reusability and the scalability, thus the software development can be easier, faster and more reliable. However, it requires a lot of time and efforts to develop an AUTOSAR software due to the difficulties of understanding of massive AUTOSAR documentations and complicated usage of AUTOSAR design tools. AUTOSAR training is offered by AUTOSAR design tool venders but it is limited to introduction of their simplified concept and usages based on PC. Therefore the training is not enough for industrial developers or graduate students. In this paper we present an AUTOSAR starter kit which allows industrial engineers and graduate students to practice the detailed process of AUTOSAR software development easily and more conveniently. The kit is composed of a practical environment similar to actual automotive system and a textbook that explains how to design AUTOSAR software. And we demonstrated the validity of our methodology based on a case study.

• Transactions of the Korean Society of Automotive Engineers
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• v.6 no.4
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• pp.76-85
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• 1998

Recently, Genetic Algorithm(GA) is widely adopted into a search procedure for structural optimization, which is a stochastic direct search strategy that mimics the process of genetic evolution. This methods consist of three genetics operations maned selection, crossover and mutation. Contrast to traditional optimal design techniques which use design sensitivity analysis results, GA, being zero-order method, is very simple. So, they can be easily applicable to wide area of design optimization problems. Also, owing to multi-point search procedure, they have higher probability of converge to global optimum compared to traditional techniques which take one-point search method. In this study, a method of finding the optimum values of suspension parameters is proposed by using the GA. And vehicle is modelled as planar vehicle having 5 degree-of-freedom. The generalized coordinates are vertical motion of passenger seat, sprung mass and front and rear unsprung mass and rotate(pitch) motion of sprung mass. For rapid converge and precluding local optimum, share function which distribute chromosomes over design bound is introduced. Elitist survival model, remainder stochastic sampling without replacement method, multi-point crossover method are adopted. In the sight of the improvement of ride comfort, good result can be obtained in 5-D.O.F. vehicle model by using GA.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.34 no.9
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• pp.33-44
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• 2006

As many scientific phenomena are now investigated using complex computer models, the effective use of Kriging on physical problems has been expanded to provide global approximations for optimization problems. This paper is focused on the two types of strategies to improve efficiency and accuracy of approximate optimization models using Kriging. These methods are performed by the stochastic process, stochastic-localization method(SLM), as the criterion to move the local domains and the design of experiments(DOE), the classical design and space-filling design. The proposed methodology is applied to the designs of 3-bar truss, Sandgren's pressure vessel, and honeycomb upper platform of a satellite structure.

• Journal of the Architectural Institute of Korea Planning & Design
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• v.34 no.8
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• pp.23-30
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• 2018

A necessity of increasing the energy efficiency of the buildings is rising due to global warming and high energy demands prices. Commissioning is an effective way to increase the energy efficiency of the building and reduce maintenance costs. In this study, a case study was conducted to derive the commissioning process of green building and propose management factors that can be used in domestic commissioning projects. The case was a university renovation project that received a LEED Glod certification and conducted the enhanced commissioning. The commissioning is divided into planning, design, construction, and post-construction phases. In the planning stage, commissioning company selection, commissioning goal setting, tasks and responsibilities for each subject are set. In the design phase, preparations are made for inspection and construction steps to prevent design errors. In the construction phase, problems are solved through periodic on-site inspections. In the post-construction phase, a final report with all the details of the commissioning will be created and future maintenance strategies will be proposed. Based on the findings of this study, it will be a basis for the management factors that can be used in the implementation of domestic commissioning projects.

• The Journal of the Korea Contents Association
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• v.12 no.8
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• pp.411-419
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• 2012

In case that R&D results from R&D projects are well managed and archived, the research institutes can transfer the valuable technologies related to R&D results with some costs to corporations. However, it is still difficult to maintain and reuse R&D results because they are managed by each person or each department and not integrated between R&D results. Therefore, the government should undertake to manage R&D results overall by collecting meta data and distribute analyzed information from meta data. Each researching institute also makes an efforts to manage R&D results focusing on their reusing. For this purpose, in this paper, we present a process to manage R&D results; insert meta data of R&D results to the system, upload files of R&D results to the database of the system, inquire, and use meta data of R&D results. Based on the process, we design a system architecture for managing R&D results. In addition, it should be mainly considered to design a global schema for integrating R&D results into one database. The system shows detailed information on R&D results and provides R&D results conveniently to users. We expect that we may reduce the cost of reusing R&D results and improve the quality of R&D results with designing efficiently a process and a global schema of R&D result management system.

• Journal of Gifted/Talented Education
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• v.21 no.2
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• pp.547-573
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• 2011

In this study, using a questionnaire about camp programs, we surveyed 375 gifted education institutes, including 285 classes for the gifted, 70 institutes for the gifted at education offices, and 20 institutes for the gifted at universities. The survey questionnaire consists of questions relating to camp design, camp operation, and camp introspection. The questions relating to camp operation are subdivided into questions relating to content, process, product, and learning environment of the camp. In the analysis of camp design, experience-centered camps entailing visits to research institutes, science museums, and so on showed the highest ratio. The camps were generally carried out in summer vacation as two day/one night programs. The average score of camp content was 3.72, that of camp process was 3.78, that of camp product was 3.77, and that of camp environment was 3.58. In the analysis of camp introspection, the item 'a lack of information about diverse camp activities' showed the highest difficult thing. Integrating these results, we suggest that information about diverse camp activities should be developed and supplied and the camp environment strengthen the freedom of students to select camp activities.