• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2013.04a
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• pp.555-558
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• 2013

A type of electric propulsion employed by specialized purpose vessels or offshore is the azimuth thruster. Azimuth thruster application had been increasing recently and resulted to excellent vessel maneuverability. However, this system is very complex and some of its major component being exposed under the seawater level presents difficulty in sealing design. For Polar class icebreaker operating in extreme sea condition, this requires a high level of reliability and safety. In this study, the characteristics of lubricating orifice pipe structural vibration installed at the lower reduction gear were investigated and analyzed through beam analysis theory and comparison of experiments. Propeller excitation and the resonant modes of vibration causing excessive vibration and suitable countermeasures to prevent damage due to vibration fatigue on the pipe are presented.

• Journal of Applied Reliability
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• v.17 no.2
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• pp.112-121
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• 2017

Purpose: The most previous works on designing accelerated life tests (ALTs) are focused on the application of a single stress. Because of the difficulty to obtain the sufficient information in a reasonable duration using single stress only, there is needed in practice to use multiple-stress ALTs frequently. This paper presents new practical plans with two stresses for Weibull distribution. Methods: The four-level practical plans based on rectangle test region are proposed and compared with the corresponding three-level statistically optimal plans. Sensitivity analyses for assumed design parameters and life-stress relationship are conducted. Results: A procedure to choose practical ALT plans is illustrated with a numerical example and guidelines for planning two-stress ALTs are provided. Conclusion: The proposed two-stress ALT plans on practical constraints to assess a quantile of Weibull lifetime distribution at the use condition are efficient and robust.

• Journal of Korean Institute of Industrial Engineers
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• v.39 no.5
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• pp.374-382
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• 2013

Robust design method developed by Genichi Taguchi has been very popular since the 1980s and there have been many academic and applied research works on this topic. However, college students and engineers in companies have had difficulty in understanding the method. This paper presents a procedure to implement the robust design method by an easy-to-execute paper helicopter experiment. A crossed array was adopted, which consists of a resolution IV fractional factorial design with 6 control factors and a factorial design with 3 noise factors. Three performance measures were analyzed; signal-to-noise ratio, mean, and standard deviation of the falling time of the paper helicopter that is to be maximized. Control-noise interaction plots are also given to evaluate the degree of the sensitivity of each level of the control factors to the noise factors. The procedure presented in this paper can be helpful to those who want to have basic knowledge in the robust design method.

• Journal of KIISE:Computer Systems and Theory
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• v.35 no.9_10
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• pp.485-496
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• 2008

As the complexity of SoC (System-on-Chip) design increases dramatically. traditional system performance analysis and verification methods based on RTL (Register Transfer Level) are no more valid for increasing time-to-market pressure. Therefore a new design methodology is desperately required for system verification in early design stages. and hardware software (HW-SW) cosimulation at TLM (Transaction Level Modeling) level has been researched widely for solving this problem. However, most of HW-SW cosimulators support few restricted ion levels only, which makes it difficult to integrate HW-SW cosimulators with different ion levels. To overcome this difficulty, this paper proposes a multipurpose framework for HW SW cosimulation to provide systematic SoC design flow starting from software application design. It supports various design techniques flexibly for each design step, and various HW-SW cosimulators. Since a platform design is possible independently of ion levels and description languages, it allows us to generate simulation models with various ion levels. We verified the proposed framework to model a commercial SoC platform based on an ARM9 processor. It was also proved that this framework could be used for the performance optimization of an MJPEG example up to 44% successfully.

• 대한공업교육학회지
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• v.39 no.1
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• pp.128-142
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• 2014

The purpose of this study was to provide a basis information for the education direction of 'creative engineering design' lesson to highschool students and pre-technology teachers by analyzing pre-experienced the d epartment of technology professors' recognitions, according to the newly opened unit 'creative engineering design' in 2009 revised highschool technology home economics education curriculum. The survey questionnaire was composed of 34 questions and collected from 16 department of technology education professors. The data was analyzed by SPSS program. The results of study were as follows : First, in 'creative engineering design' educational objectives, the highest average level(M) of response was problem solving ability, the opportunity of engineering experience and creativity improvement were followed. In the response about 'creative engineering design' educational contents, the average level(M) of the creative thinking method education was the highest(3.94). and the following important level was the write training education for presentation. Second, in the 'creative engineering design' educational areas, the professors preferred the idea conception, design, and production manufacturing area. In the teaching learning method, the average level(M) of design-based learning method was the first. and PBL, problem solving method were favored Third, in the 'creative engineering design' lesson manage, the secure of practice room and material cost, and the check of the progress situations were needed preferentially. In the education assessments, various and combined assessment preferred such as production, portfolio, and presentation. Fourth, in the pre-technology teachers' lesson of the university course, the product manufacturing level was preferred production to improve uncomfortable thing in life. The major difficulty in product manufacturing was the lack of major knowledge and product conception.

• IEMEK Journal of Embedded Systems and Applications
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• v.2 no.3
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• pp.145-154
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• 2007

Dynamic update of kernel can change kernel functionality and fix bugs in runtime. Dynamic update is important because it leverages availability, reliability and flexibility of kernel. An instruction-granularity update technique has been used for dynamic update. However, it is difficult to apply update technique for a commodity operating system kernel because development and maintenance of update code must be performed with assembly language. To overcome this difficulty, we design the function-granularity dynamic update system which uses high-level language such as C language. The proposed update system makes the development and execution of update convenient by providing the development environment for update code which is same for kernel development. We implement this system for Linux and demonstrate an example of update for do_coredump() function which is reported it has a vulnerable point for security. The update was successfully executed.

• International Journal of Contents
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• v.10 no.2
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• pp.37-41
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• 2014

This study defined the pre-elderly as middle age people from 50 to 59. Because it is difficult to produce a design to satisfy the pre-elderly without deeply understanding them, their financial and physical characteristics and persona-based scenario method was studied. An experimental study about persona based scenario method was conducted, and as a result, the types of personas found were as follows: 1) Users enjoy the same games online and offline. 2) Users enjoy playing alone on the computer. 3) Users prefer games that end quickly with win or loss. Writing the situation scenario for each type, the pre-elderly's problems and needs occurring while they play web board games were obtained. The obtained user requests were as follows: users would like the level of difficulty to be simpler in the game of baduk; users wanted unlimited credit and refrainment from using English words in go-Stop; and there were simple comments about game screen design.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.28 no.11
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• pp.1656-1663
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• 2004

As the structures become larger, higher and more complicated, the demand for safety level has increased. In recent years, TLD(Tuned Liquid Damper) proved to be a successful control tool for reducing structural vibrations. For this reason, the influence of some key parameters of the U-type TLD on the dynamic response is studied. And simple and effectively developed learning control logic is used to control vibration of U type Tuned Liquid Damper system. The purpose of this paper is design optimal control system to deal with unknown errors from non linearity and variation that cost modeling difficulty in complex structure and is followed with the desired behavior. Finally this hybrid control method applied to U type Tuned Liquid Damper structure gives the benefit from better performance of precision and stability of the structure by reducing vibration effect. This research leads to safety design in various structure to robust unspecified foreign disturbances such as windy-load and earthquake.

• The Journal of the Korea Contents Association
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• v.9 no.11
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• pp.363-375
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• 2009

This study is to verify effects of banner advertising by context effect in web contents. For this, it analyzed the effects of banner advertising by association of internet article's contents, emotion, difficulty of article and the level of involvement. According to the result of experimental design, banner advertising effects by context effects of web contents were high in the following cases; in the case when the contents were highly associated with banner advertising; in the case when the positive emotions were formed by the internet article; in the case when the difficultly of article was low; and in the case when consumer's involvement was high. And also, when the contents were highly associated with the advertising, the content effects of web contents were high even in the case when the negative emotions were formed; in the case when the difficulty of article was high; and consumer's involvement was low.

• The Journal of Korean Association of Computer Education
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• v.6 no.2
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• pp.1-8
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• 2003

In existing the learner testing system, it has a weak point to determine differently the difficulty of each question which has been estimated by teacher's view and the subjective stand point. In this paper, we develops the learner testing system which supports the estimation of the individual ability of learner, provides the questions for suitable to the individual learner level, and able to estimate the question of individual that used by three parameters such as the difficulty parameter, discrimination parameter, and guessing parameter. Also, it is applied to three-parameters logistic model of IRT(Item Response Theory) for using CAT(Computer Adaptive Testing) technique.