• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.11a
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• pp.214-219
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• 2003

Recently, the optical disk drive that is thin in thickness has been demanded by the popularization of notebook PC. The device that controls the thickness of a drive is the height of optical pickup. Therefore, researches about this are going on and an asymmetric actuator is the good choice fur this target. However, the actuator of this design has troubles that a subsidiary resonance is likely to be actuated by discord between the center of force and the mass of renter. In this paper, relation between the tracking coil and the subsidiary resonance is analyzed and dynamic characteristics of an actuator are improved by using experiments design and response surface method.

• Journal of Educational Research in Mathematics
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• v.12 no.2
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• pp.229-246
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• 2002

In this paper, we start with the question "what is algebraic thinking\ulcorner". The problem is that the algebraic thinking is not exactly defined. We consider algebraic thinking from the various perspectives. But in the discussion relating to the definition of algebraic thinking, we verify that there is the algebraic notations in the core of algebraic thinking. So we device algebraic notations into the six categories, and investigate these examples from the school mathematics. In order to investigate this relation of algebraic thinking and algebraic notations, we present 'the algebraic thinking process analysis model' from Frege' idea. In this model, there are three components of algebraic notations which interplays; sense, expression, denotapion. Thus many difficulties of algebraic thinking can be explained by this model. We suppose that the difficulty in the algebraic thinking may be caused by the discord of these three components. And through the transformation of conceptual frame, we can explain the dynamics of algebraic thinking. Also, we present examples which show these difficulties and dynamics of algebraic thinking. As a result of these analysis, we conclude that algebraic thinking can be explained through the semiotic aspects of algebraic notations.

• Proceedings of the SAREK Conference
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• 2007.11a
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• pp.429-433
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• 2007

Cement mortar and concrete can be used as grouts but problems regarding shrinkage and the discord of coefficients of thermal expansion between grouts and HDPE pipes has to be solved. Thermal conductivities of wet condition two times larger than those of dry condition, except for pure cement mortar. The addition of sand into the cement grouts greatly increases the thermal conductivity. The addition of bentonite into the cement grouts reduces thermal conductivity thus reducing the density. Bentonite grouting must be used only below the groundwater table since bentonite grouts possesses high shrinkage property in dry condition. The addition of sand prevents the shrinkage of bentonite grouts. Bentonite manufactured in Korea can be used since they possess similar thermal conductivities with imported products. The addition of sand into the bentonite grouts greatly increases the thermal conductivity.

• Korean Journal of Child Studies
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• v.27 no.3
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• pp.117-133
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• 2006

Twenty-one adoptive parents participated in this study on adoption-related conflicts perceived by adoptive parents in open adoption. Q-methodology, which provides understanding of individual attitudes and experiences, identified three types of conflict. Type 1 experienced a great deal of conflict and concern prior to the adoption decision; they also faced difficulties stemming from lack of information about parenting an adopted child and institutional inertia. For type 2, the major factors of conflict were discord among siblings, negative bias against adoption in the community, and insufficient national assistance. Type 3 reported that they feel concerned for their adopted-child's developmental and psychological wellbeing they worried that adoption status might lead to behavioral and attitudinal problems in their adopted-child during youth and young adulthood.

• Proceedings of the Korean Institute of Interior Design Conference
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• 2008.05a
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• pp.163-168
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• 2008

In a today, our concerns have been changed from a single material to relation, communication and time. The human life made up of science, technology, philosophy and art of the modern society can decide whoerness by connecting or replacing a comprehensive and many kinds. This one is exhibited in interior actively. The space of the pluralistic world is sustained by not simple and fixed relation but complex and flexible relation. And it is shown as an undecided phenomenon by effecting and modifying each other. In here, the boundary has a phase of undecided relation but at the same time it can make possibility to be abundant to infinity. The purpose of our study with considering the uncertainty of the boundary is to solve the discord of between division and unify of modern architecture space and suggest new way to be mediation and to occupy independent area.

• Proceedings of the Korean Institute of Interior Design Conference
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• 2005.10a
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• pp.71-75
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• 2005

For last century, our country fast changed by development of industry but we justly looked away that cultural and natural environment that must preserve inside the change, and we sought quantitative growth. But consciousness about culture is rising now; thereby social request becomes strong that is improved cultural environment; and viewpoint is appearing which is thought heftily cultural environment of city. Important thing of them is the modern age architecture, but serious discord is happening in the current society that allows conservation and destruction of the modern age architecture. But, visible cultural asset such as the modern age architecture is value when it protected as the first time, When it was broken! , restoration or age architecture really necessary to us.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1996.10a
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• pp.175-181
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• 1996

The magnetic levitation system is utilized in the magnetic bearing of high-speed rotor because of little friction, no lubrication, no noise and so on. The magnetic levitation system need the feedback controller for the stabilization of system, and gap sensors are usually used to measure the gap. The use of sensor is troublesome such as sensor trouble, discord between the measurement point and the control point etc. This paper presents the design of robust stabilizing controller by H$_{\infty}$ control theory using the sensorless method proposed already by authors in the magnetic levitation system. And we investigated both the validity of the designed controller and the usefulness of the sensorless method proposed by authors of magnetic levitation system through results of actual experiment..

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.11a
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• pp.577-580
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• 2005

This paper reports the high sensitivity actuator for flexible disk. The air stabilized flexible optical disk has very small axial runout. Therefore, It is proper to develop an actuator which has high sensitivity in tracking direction rather than in focusing direction. In order to maximize driving force in radial direction, we present an efficient design of magnetic circuit with simple multi-polarized magnets and auxiliary magnets. Designed magnetic circuit has big force in tracking direction. And we shift 2$^{nd}$ resonance frequency of moving parts Into high frequency band, not causing increase of mass and discord between force and mass centers to secure high sensitivities and sufficient control bandwidth. Finally, experimental results show that designed actuator has superior sensitivity in tracking direction.

• Journal of the Korea Society for Simulation
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• v.11 no.4
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• pp.33-41
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• 2002

One of the key issues in mobile communication system is how to predict the number of calls per each cell. It is an important parameter and usually assumed as random Poisson value. For effective management of cellular network, the average number of calls should be traced and the changes in the numbers need to be promptly detected. In this paper we propose an algorithm detecting the changes in the demands of the users using the technique proposed for point-of-change problem based only on the number of call arrivals. Computer simulation reveals that the proposed method can effectively detect the discord, and the developed model is very accurate as showing mostly less than 1% differences.

• American Studies
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• v.32 no.1
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• pp.169-198
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• 2009

Unlike the Democratic nomination, Republican nomination struggle has ended with an easy victory of Senator John McCain. This paper claims that the easy victory of McCain should not be interpreted as Republican's return to the median voter, because it masks religious schism and ideological discord among the Republicans. Christian rights were still reluctant to support McCain mostly due to his liberal position on social issues. In addition, the conservatives who request stricter immigration policy presented the mixed feeling toward the Republican candidate. Even though McCain chose the harmony inside the Republican party, rather than sticked to his liberal attitude toward social issues during the campaign for 2008 general election, McCain's defeat is unlikely to result in a rapid change in the Republican party.