• Proceedings of the KSME Conference
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• 2008.11a
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• pp.1215-1220
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• 2008

The aim of this paper is to perform a finite element analysis that will have the ability to predict the seal performance characteristics, such as deformation, contact load and friction and also is to provide a means of potential seal designs, which can reduce the time and cost of designing the performance of the seal. The material property tests of elastomer seal are performed to obtain the hyperelastic properties and The Mooney-Rivlin constants are determined from these test results. A 2D modelling of the seal cross section is performed to simulate the contact behavior between the seal on the piston and the cylinder bore under operation conditions. The deformation behavior, contact load and friction of an elastomer seal is analyzed by a finite element method which performs three analytic phases of interference fit, the variations of pneumatic pressure and piston movement under the operational conditions.

• Asia pacific journal of information systems
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• v.8 no.2
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• pp.85-104
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• 1998

It is assumed that employees' ethical judgements and attitudes in handling personal and organizational information differ, depending upon their hierarchical ranks in organizations and types of information. Therefore we investigated how differently employees at different ranks judge hypothetical behaviors(or situations); their manner of handling various types of information in their daily activities in business organizations. Sixteen hypotheses based on combinations of 3 ethical areas and 5 information types were developed and tested. We found that three management ranks have shown significantly different ethical attitude about i)the accessibility to strategic planning and managerial information and ii)the property of managerial, operational and informal information. This research can help organizations to design better education programs and ethical codes to guide employees who process sensitive information.

• Journal of IKEEE
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• v.19 no.4
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• pp.465-471
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• 2015

An LC-tuned sinusoidal voltage-controlled oscillator (VCO) using temperature-stable linear operational transconductance amplifiers (OTAs) is presented. Its architecture is based on Hartley oscillator configuration, where the inductor is active one realized with two OTAs and a grounded capacitor. Two diode limiters are used for limiting amplitude. A prototype oscillator built with discrete components exhibits less than 3.1% nonlinearity in its current-to-frequency transfer characteristic from 1.99 MHz to 39.14 MHz and $220ppm/^{\circ}C$ frequency stability to the temperature drift over 0 to $75^{\circ}C$. The total harmonic distortion (THD) is as low as 4.4 % for a specified frequency-tuning range. The simulated phase noise of the VCO is about -108.9 dBc/Hz at 1 MHz offset frequency in frequency range of 0.4 - 46.97 MHz and property of phase noise of VCO is better than colpitts-VCO.

• Proceedings of the Korea Society for Simulation Conference
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• 2005.05a
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• pp.34-39
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• 2005

The progress of silicon technology enables to implement a highly complex digital system on a given chip area. However, even the modern design environment is not so efficient to catch up with the progress of process technology. Design reuse is a promising approach to designing such a complex system in an efficient way. However, the rigidness and inflexibility of a model has been an obstacle to design reuse. This paper proposes a high-level model management methodology by introducing attributed AND-OR graph(AOG), a (formal semantics for representing the possible structure of a model. Using the formalism enables a designer to extract, extend and reuse the pre-modeled and pre-verified design. A complete process of constructing a cache operational model, extending the model and extracting executable models is exemplified to show effectiveness of the proposed framework.

• Proceedings of the KIEE Conference
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• 2003.07c
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• pp.1609-1611
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• 2003

This paper presents the results on the development of capacitive sensor for the diagnosis of electrical insulating oil, widely used for power transformer. To survey the dielectric properties of the new and used mineral insulating oil, we utilized the highly precise measuring system of KRISS. And the results were used to determine the design factors of the sensor. To evaluate the operational and the hysteresis characteristics of the sensor, we constructed a test chamber, including dielectric property measuring system. Through the results we could confirm the superior characteristics of the newly developed sensor.

• International Journal of Reliability and Applications
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• v.4 no.4
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• pp.183-190
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• 2003

Rail breaks and derailments can cause a huge loss to rail players due to loss of service, revenue, property or even life. Maintenance has huge impact on reliability and safety of railroads. It is important to identify factors behind rail degradation and their risks associated with rail breaks and derailments. Development of mathematical models is essential for prediction and prevention of risks due to rail and wheel set damages, rail breaks and derailments. This paper addresses identification of hazard modes, estimation of probability of those hazards under operating, curve and environmental condition, probability of detection of potential hazards before happening and severity of those hazards for informed strategic decisions. Emphasis is put on optimal maintenance and operational decisions. Real life data is used for illustration.

• Journal of the Korea Institute of Military Science and Technology
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• v.24 no.4
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• pp.449-456
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• 2021

Impatience characteristics are an important factor to be considered in the defense field, which is sensitive to time, but there are not many cases applied. In addition, due to the difficulty of analysis that must consider various probabilistic factors (breakdown/maintenance distribution, impatience characteristics, etc.), military decision makers consider only simple data (number of occurrences per year, maintenance time, etc.) Therefore, in this study, a model capable of analyzing the performance of the emergency maintenance system for determining the appropriate size and organization of military and civilian maintenance personnel was presented in consideration of impatience characteristics and probabilistic factors. And through numerical analysis, the appropriate size of the military and civilian emergency maintenance teams was analyzed. This study is significant in that it can improve readiness of operational power and prevent waste of defense budget through efficient operation of the military's emergency maintenance system.

• East Asian mathematical journal
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• v.38 no.2
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• pp.257-275
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• 2022

Recently, there are studies the argument that arithmetic rules established by the four fundamental arithmetic operations, in other words, commutative laws, associative laws, distributive laws, should be explicitly described in mathematics textbooks and the curriculum. These rules are currently implicitly presented or omitted from textbooks, but they contain important principles that foster mathematical thinking. This study aims to evaluate the current level of understanding of these computation rules and provide implications for the curriculum and textbook writing. To this end, the correct answer ratio of the five arithmetic rules for 1-4 grades 398 in five elementary schools was investigated and the type of error was analyzed and presented, and the subject to learn these rules and the points to be noted in teaching and learning were also presented. These results will help to clarify the achievement criteria and learning contents of the calculation rules, which were implicitly presented in existing national textbooks, in a new 2022 revised curriculum.

• International conference on construction engineering and project management
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• 2015.10a
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• pp.578-582
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• 2015

Lack of client involvement in construction of public projects has been identified as the main cause of many operational problems. Clients need to perform their roles and responsibilities effectively and efficiently at the right time and through the use of correct methods in order to have the optimum involvement required during all the construction project phases, namely, the planning, design, construction, handover, and operation and maintenance phase. This paper investigates the influence of clients' individual factors on their involvement in construction project delivery. A questionnaire survey was distributed to various government agencies of the Kingdom of Saudi Arabia (KSA). Explanatory Factory Analysis was performed to group nineteen individual factors. The factor analysis result suggests that the individual factors that can involve clients' involvement in construction projects can be grouped into five, which are: adequacy of knowledge and experience for decision making in the early stage of design; ability to communicate clearly; job satisfaction; personal skills; and expertise in design and construction.

• ETRI Journal
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• v.46 no.3
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• pp.367-378
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• 2024

We propose a number-theory-based quantized mathematical optimization scheme for various NP-hard and similar problems. Conventional global optimization schemes, such as simulated and quantum annealing, assume stochastic properties that require multiple attempts. Although our quantization-based optimization proposal also depends on stochastic features (i.e., the white-noise hypothesis), it provides a more reliable optimization performance. Our numerical analysis equates quantization-based optimization to quantum annealing, and its quantization property effectively provides global optimization by decreasing the measure of the level sets associated with the objective function. Consequently, the proposed combinatorial optimization method allows the removal of the acceptance probability used in conventional heuristic algorithms to provide a more effective optimization. Numerical experiments show that the proposed algorithm determines the global optimum in less operational time than conventional schemes.