• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 1995.04a
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• pp.65-92
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• 1995

The final aim of our research project is a study on assessment of automatic steering system of ships in open seas. In order to achieve this aim we need to know the characteristics of each component of the system and also to know the characteristics of disturbance to ship dynamcis. In this paper we provide calculation method of irregular disturbance to ships in autopilot navigation in open seas and also show calculation examples about two kinds of ship ore carrier and fishing boat. The disturbance consists of irregular wave and random wind, The disturbance is calculated as equivalent yaw angular velocity. Each spectrum and time history of disturbance are reasonably evaluated. Further investigation concerning to performance index of autopilot system and energy loss related to automatic course keeping will be dealt with in another paper,

• Transactions of the Korean Society of Mechanical Engineers B
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• v.23 no.9
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• pp.1121-1128
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• 1999

A single blow, transient testing method for determining the heat transfer characteristics of heat exchanger surfaces are presented. The exponential inlet temperature variations were made using screen mesh with small time constant and frontal velocities of the test section. The system is used to investigate the usefulness of a model with exponential inlet temperature variations. A data reduction program is developed to calculate the temporally and spatially averaged heat transfer coefficient using the measured disturbance and response of the fluid temperature. The results are compared with the existing theoretical and experimental data for parallel plate stacks. It was recommended to take an average for the time greater than the 99% of the final temperature had reached in order to obtain fairly good results.

• Proceedings of the KSME Conference
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• 2007.05a
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• pp.1277-1281
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• 2007

A Nano-tip as a cold field emitter for inducing a field emission current has manufactured in many ways. In the paper, the electrochemical etching method is used. Thus, in order to optimize the final shape as the field emitter, the reliable fabrication system for electrochemical etching was constructed. In addition, the effective parameters such as applied voltage, submerged length, meniscus height, electrolyte concentration and environmental condition(vibration, humidity, cut-off time) have investigated in detail. By controlling the parameters, reliable tungsten tip for field emitter was fabricated. And the fabricated tungsten tip was evaluated optically. Finally, the very sharp apex of the tungsten tip was observed with scanning electron microscope.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 2002.10a
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• pp.313-316
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• 2002

This study was performed to evaluation the consolidation behavior of agricultural reservoir in the very soft ground. The final settlement prediction methods by Hyperbolic and Asaoka methods were used to compare with the degree of consolidation estimated by exess pore water pressure. The dissipated excess pore water pressure during embankment construction and peak excess pore water pressure on the completed embankment were suggested for the estimation of the degree of consolidation. It was concluded that the degree of consolidation estimated from dissipated excess pore water pressure was more reliable than that from the peak excess pore water pressure.

• School Mathematics
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• v.1 no.1
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• pp.187-216
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• 1999

The purpose of this study is to develop mathematics performance assessment items for the 8th graders and to analyze their performance ability. First, five-themes were selected : 'Calculator', 'Cut and Paste', 'Rule finding', 'Place Assignment', 'My thinking'. Then, the assistance of Mathematics education specialists and Teachers, 10 P. A. items consisting of two subtasks and their evaluation rubric were developed. Then, items were revised by the results of pilot test. And, final version of items were administrated to the 8th graders of three regions(Seoul, Chongiu, Chungp$\acute{y}$ong). Through analyzing the performance ability of the subjects assessment items, the following conclusion were obtained: They were very insufficient in the ability to find some patterns in the given problem situation and to describe logically the patterns in terms of mathematical terminology. It is believed because they were familiar with the objective test to take one or short answer.

• IE interfaces
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• v.5 no.2
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• pp.3-17
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• 1992

In this study, an integrated economic analysis model to analyze the new telecommunication services is developed. This model considers both the technological and managerial aspests altogether with respect to the profit and public benefit criteria. To encounter the various dynamically changing environments and evaluation criteria, multiple criteria decision making (MCDM)techniques are employed. The model consists of three stages; The first stage surveys related formal or informal data, generates analysis alternatives, and performs acceptabillty test in view of marketing. The second stage generates executive alternatives for each acceptable analysis alternative and checks the executionability in view of telecommunication technologies. The third stage performs the final integrated economic analysis including the profitability analysis. This study offers a basis for the future development of decision support system or expert system on the economic analysis of the new telecommunication services.

• Journal of The Korean Society of Agricultural Engineers
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• v.52 no.4
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• pp.45-52
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• 2010

The purposes of this research are to analyze the internal settlement behavior of Concrete Faced Rockfill Dam (CFRD) typed 'D dam' and to evaluate the stability of the 'D dam' during dam construction using internal settlement measurements and results of numerical analysis. The field measurements were obtained during dam construction period. The numerical analysis was also carried out for the same construction period. The numerical analysis focused mainly on prediction of stress and displacement behavior of 'D dam' during dam construction stage using input parameters obtained from laboratory tests, i.e. large triaxial tests. The behavior of 'D dam' was evaluated to be stable from comparing the results of field measurements and numerical analysis. A simple empirical equation is also presented to predict final settlement at the completion of dam construction, using settlement measurement monitored during dam embankment.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2008.10a
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• pp.8-23
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• 2008

The purpose of this study is to develop a Cross Impact System Alternatives Tree(CISAT) model necessary for selecting the interdependent R&D planning system alternatives. This model modifies System Alternatives Tree(SAT) model developed by Kwon et al.. The SAT model is composed of several functions necessary for the achievement of a final goal and several subsystems for satisfying each function. In case that the relationship of technology alternatives is interdependent, this model overlooked a relative importance derived from occurrence or nonoccurrence of the technology alternatives in the future time varience. However, a complex evaluation process within the ballot system is another disadvantage of the SAT. To solve such problems, the Cross Impact Analysis(CIA) model is applied in the SAT model so as to consider the cross impact among interdependent system alternatives.

• Proceedings of the Korea Concrete Institute Conference
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• 1999.04a
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• pp.229-232
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• 1999

Nuclear power plant structures may be exposed to aggressive environmental effects that may cause their damage mechanisms are reasonably well understood and quantitative evaluation of their effects on time-dependent structural behavior is possible in some instances, such evaluations are generally very difficult and remain novel. The assessment of existing steel containment in nuclear power plants for continued service must provide quantitative evidence that they are able to withstand future extreme loads during a service period with an acceptable level of reliability. Rational methodologies to perform the reliability assessment can be developed from mechanistic models of structural deterioration, using time-dependent structural reliability analysis to take loading and strength uncertainties into account. The final goal of this study is to develop the analysis method for the analysis for the reliability of containment structures. The cause and mechanism of corrosion is first clarified and the reliability assessment method has been established. By introducing the equivalent normal distribution, the procedure of reliability analysis which can determine the failure probabilities has been established.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.11a
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• pp.93-96
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• 2005

Since the columns with flexure-shear failure have lower ductility than those with flexural failure, shear capacity curve models shall be applied as well as flexural capacity curve in order to determine ultimate displacement for seismic design or performance evaluation. In this paper, a modified shear capacity curve model is proposed and compared with the other models such as the CALTRANS model, Aschheim et al.'s model, and Priestley et al.'s model. Four shear capacity curve models are applied to the 4 full scale circular bridge column test results and the accuracy of each model is discussed. It may not be fully adequate to drive a final decision from the application to the limited number of test results, however the proposed model provides the better prediction of failure mode and ultimate displacement than the other models for the selected column test results.