• Journal of Korean Society of Transportation
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• v.14 no.1
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• pp.43-50
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• 1996

This paper is concerned with assessing goodness of fit of gravity models. The Chi-square test, or one of its asymptotic equivalents, is usually recommended for the purpose. A difficulty that frequently arises, particularly when working with urban travel data, is that the expected number of trips for most origin-destination(O-D) pairs are small. In order to test goodness of fit of gravity model, a simple approach, which depends on the number of O-D pairs and certain trip totals being large, is proposed in this paper. In addition, derivation of variance of Chi-square ratio is proposed to test the confidence interval of Chi-square ratio and application of its results with simulated data set is made to verify the usefulness of the results.

• The korean journal of orthodontics
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• v.43 no.4
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• pp.201-206
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• 2013

This article describes the orthodontic treatment of a 25-year-old Korean female patient with anterior crowding, including palatally displaced lateral incisors. Her facial profile was satisfactory, but 3.5 mm of maxillary anterior crowding was observed. To correct this crowding, we decided to minimize the use of the conventional fixed orthodontic appliances and employed a less bulky and more aesthetic appliance for applying light continuous force. We determined the final positions of the maxillary teeth via a working model for diagnostic set up and achieved space gaining and alignment with simple Ni-Ti spring and stainless steel round tubes. Tooth alignment was achieved efficiently and aesthetically without the conventional brackets.

• Journal of Advanced Marine Engineering and Technology
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• v.18 no.5
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• pp.46-55
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• 1994

The purpose of this research is to construct experimental test set-up and to establish a series of performance test program for the domestically developed hydraulic couplings, and to provide a software to store and utilize these experimental data which can be used to improve the performance of the hydraulic coupling and solve the job problems confronted during operation. The performance test consists of measurement of torque, rpm and efficiency of the hydraulic coupling for three different amounts of working fluid with various loads to the output shaft, and investigating the torque, rpm and efficiency characteristics with respect to these parameters. The results of this study can contribute to the development of variable speed hydraulic coupling and torque converter pursued by the domestic industry.

• Journal of Advanced Marine Engineering and Technology
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• v.10 no.4
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• pp.31-40
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• 1986

With the tendency toward high speed and high pressure in centrifugal pumps, the problem of sub-synchronous vibration has arisen, caused by the hydraulic forces of the working fluid, such as wearring, balance piston, impeller, etc.. These forces can drastically alter the rotor critical speeds and stability characteristics, and can be acted significant destabilizing forces. For preventing such self-excited vibration, the desing of the rotor system needs, which would secure the stability of the machine. In this paper, a procedure is presented for dynamic modeling of rotor-bearing-seal-impeller systems which consist of rigid disks, distributed parameter finite rotor elements and discrete bearings, seals and impellers. A finite element model including the effects of rotatory inertia and gyroscopic moments is developed using the consistent matrix approach. The technique of dynamic matrix reduction is applied to the shaft matrices to reduce them to a set of matrices of dynamic of significantly fewer degrees of freedom. The representation of bearing, seal and impeller elements is in term of linearized stiffness and damping matrices by reasonably small perturbations from equilibrium. The stability behavior of a typical double suction centrifugal pump is presented. Results show the influence of clearance and flow conditions on running speeds and stability characteristics.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.25 no.4
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• pp.76-82
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• 2017

I studied existing research and thesis which are relating emotional labor, job-related stress, and service level to set up the structural model and potential factors that form this structural model. The result showed that emotional labor is affecting job-related stress, service delivery level and customer-oriented activities. And service delivery level is affecting customer-oriented activities under 95% confidence levels. Also from the analysis of group survey by working group, check-in agent's emotional labor is affecting on job-related stress, service delivery level and customer-oriented activities. And service level is affecting on customer-oriented activities. By the result of how emotional labor and customer-oriented activities are related, I strongly believe it contributed the study of emotional labor theory.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.05a
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• pp.338-341
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• 2002

A human-friendly interactive system, based on the harmonious symbiotic coexistence of humans and robots, is explored. Based on this interactive technology paradigm, a robotic cane is designed to help blind or visually impaired travelers to navigate safely and quickly among obstacles and other hazards faced by blind pedestrians. We outline a set of the hardware solutions and working methodologies that can be used for successfully implementing and extending the interactive technology to complex environments, robots, and humans. The issues discussed include the interaction of human and robot, design issue of robotic cane, hardware requirements for efficient human-robot interaction.

• International Journal of Contents
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• v.10 no.1
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• pp.12-17
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• 2014

This paper will explore the problem of domestic violence in the UK. It will begin by defining the problem and then set out estimates of the extent of the problem, while also examining the problems that are involved in measurement. It will then examine the policing strategies that have been put in place to tackle this problem, such as intelligence gathering, effective investigations, and risk management techniques. The paper will also highlight the importance of multi-agency involvement when dealing with domestic violence and the wide range of orders that have been created in order to help deal with this problem.

• Journal of the Korean School Mathematics Society
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• v.1 no.1
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• pp.35-45
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• 1998

This paper will present some basic and simple graphical methods of exploratory data analysis for the instrument of data analysis at school mathematics. Human beings perceive visual patterns more readily than patterns in collections of numbers. This is especially important in exploratory data analysis because pictures dramatically reveal things that we did not expect to find in the data set. Here are graphical methods as the stem and leaf plot, the box plot, the star plot and the face plot. These methods impulse the motivation of students in real life. And the subject can be taught in secondary school with several applications. Also It is important for students to get a feel for working with and manipulating data before studying the more theoretical aspects of statistics.

• Transactions of the Korean Society of Automotive Engineers
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• v.10 no.4
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• pp.114-121
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• 2002

This paper describes the control system of the toroidal traction driver continuously variable-speed transmission(CVT) fur a tractor. The instrumentation system, the hydraulic power control system and the principle control scheme were introduced. Experimental tests in the bench and the tractor were conducted to validate the performance of the CVT utilizing the proposed controller. The speed of the vehicle was continuously changed to follow the speed set by driver under various operating conditions. Given the reduction ratio of the variator from 2.0 to 1.0, the settling time was about just 0.52 seconds which was satisfactory value for working with the tractor. It was also proved that the tractor could work with continuously variable speed under heavy load disturbances.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.15 no.1
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• pp.1-10
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• 2007

When detonation is occurred, the working fluid is compressed itself, though there are no other devices that compress the fluid. As a result, an engine which uses detonation for a combustion process doesn't need moving parts so that the engine can be lighter than other engines ever exist, and such an engine is often referred to as a pulse detonation engine. Since using detonation has higher performance than using deflagration, many studies have been attempting to control and analyze the engines using detonation as combustion. The purpose of this study is to analyze the hybrid cycle which is consisted of Brayton and Pulse Detonation Engine cycle. At first, we set the theoretical basis of detonation analysis, and after that we consider two hybrid cycles; a turbojet hybrid cycle and a turbofan hybrid cycle. The more energy released, the higher detonation Mach number the detonation wave has. In general, a cycle which has a detonation process has higher performances but thermal efficiency of hybrid turbofan engine.