• The korean journal of orthodontics
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• v.21 no.3
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• pp.603-614
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• 1991

To study the possibility of attraction magnetic forces to expand maxillary arch, we used 2 big adult dogs, 2 small puppies, 1 small adult dog as experiments, and 1 small adult dog as a control. We measured the intercanine width and intermolar width and histologically observed in the suture and cervical and apex region of teeth and took occlusal X-rays to observe separation of suture line in the maxilla. The results were as follows: 1. Expansion velocities of intercanine (0.25mm/day) and intermolar widths (0.23mm/day) in puppies were faster than those (0.135mm/day, 0.09mm/day) in adults. 2. In all experiments in adults (0.135mm/day) and puppies (0.25mm/day), expansion velocity of intercanine widths were faster than those (0.09mm/day, 0.23mm/day) of intermolar width. 3. In all experiments ectatic changes were observed and cellularities of fibroblast increased in the suture line. Only in adults dogs the separations of palatal suture were observed in the occlusal X-ray view. 4. In the puppies bony deposition was particularly observed in the suture line and micro-bony fragments were often observed. 5. In the all experiments no root resorption was observed in the cervical and root area, but normal root resorption due to eruption of permanent teeth was observed in the puppies.

• Journal of Powder Materials
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• v.17 no.4
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• pp.326-335
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• 2010

In this paper, the effect of electrical characteristics and electrode shape on the alignment and attachment of multi-walled carbon nanotubes (MWNTs) has been studied. The attraction and alignment of MWNTs between the gaps has been investigated by applying electric field which is called electrophoresis and dielectrophoresis. According to the frequency of electric field, positive or negative dielectrophoretic force can be determined. The concentration of MWNTs solution was $5\;{\mu}g/ml$, and a droplet of $1.0{\sim}1.5\;{\mu}l$ was dropped between two electrodes. Through the repeated experiments, the optimal electrical conditions for aligning and attaching MWNTs in the desired places were obtained. Since the frequency range of 100 kHz~10 MHz generated positive dielectrophoretic force, MWNTs were attracted and aligned between the gaps with this frequency range. For generating enough force to attract MWNTs, the appropriate voltage range was $0.3{\sim}1.3\;V_{rms}/{\mu}m$. Furthermore, the effect of electrode shape on the alignment of MWNTs was investigated. A single MWNT attachment was accomplished on the round shaped with 70% yield.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.37 no.6
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• pp.545-550
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• 2013

We present a tactile information transceiver using a friction-tunable slider-pad. While previous tactile information devices were focused on either input or output functions, the present device offers lateral position/vertical direction detection and texture expression. In characterizing the tactile input performance, we measured the capacitance change due to the displacement of the slider-pad. The measured difference for a z-axis click was 0.146 nF/$40{\mu}m$ when the x-y axis navigation showed 0.09 nF/$750{\mu}m$ difference. In characterizing the texture expression, we measured the lateral force due to a normal load. We applied a voltage between parallel electrodes to induce electrostatic attraction in DC and AC voltages. We measured the friction under identical fingertip action conditions, and obtained friction in the range of 32-152 mN and lateral vibration in the force range of 128.1 mN at 60 V, 2 Hz. The proposed device can be applied to integrated tactile interface devices for mobile appliances.

• Journal of the Korean Institute of Traditional Landscape Architecture
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• v.33 no.3
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• pp.103-113
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• 2015

This study is an evaluation index development research based on Gyeongju Historic Heritage Sites to identify the attractive Properties of Gyeongju, which decided to competitiveness of the historical city. We got the export Indicator candidate groups by the literature reviews and UNESCO, ICOMOS, and 49 Indicator candidate groups had been selected. In the end, we chose 42 attraction indexes in charm of the cultural heritage side, Cultural heritage tourism resources Side, Restraining force Heritage tourism Side three aspects based on the analysis of Importance(M), Standard deviation(SD), Content Validity Ratio(CVR), Agreement, convergence by using Delphi Technique. We can determine these indicators will be useful basic information, for improving the city's historic attractions. In the future, used these indicators as a basis for Attractions effectiveness evaluation of Gyeongju, Through which the attractions of Gyeongju can be re-recognized.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.40 no.3
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• pp.99-106
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• 2017

With the increased interest in the quality of life of modern people, the implementation of the five-day working week, the increase in traffic convenience, and the economic and social development, domestic and international travel is becoming commonplace. Furthermore, in the past, there were many cases of purchasing packaged goods of specialized travel agencies. However, as the development of the Internet improved the accessibility of information about the travel area, the tourist is changing the trend to plan the trip such as the choice of the destination. Web services have been introduced to recommend travel destinations and travel routes according to these needs of the customers. Therefore, after reviewing some of the most popular web services today, such as Stubby planner (http://www.stubbyplanner.com) and Earthtory (http://www.earthtory.com), they were supposed to be based on traditional Traveling Salesman Problems (TSPs), and the travel routes recommended by them included some practical limitations. That is, they were not considered important issues in the actual journey, such as the use of various transportation, travel expenses, the number of days, and lodging. Moreover, although to recommend travel destinations, there have been various studies such as using IoT (Internet of Things) technology and the analysis of cyberspatial Big Data on the web and SNS (Social Networking Service), there is little research to support travel routes considering the practical constraints. Therefore, this study proposes a new mathematical model for applying to travel route recommendation service, and it is verified by numerical experiments on travel to Jeju Island and trip to Europe including Germany, France and Czech Republic. It also expects to be able to provide more useful information to tourists in their travel plans through linkage with the services for recommending tourist attractions built in the Internet environment.

• Journal of the Korea Society for Simulation
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• v.26 no.3
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• pp.47-54
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• 2017

This paper analyzed the motion characteristics of two ships according to the ship's dimension using Ship Handling Simulator. When the panamax container ship passes the smaller ship, peak point and patterns of interaction forces for the moored ship are noticeable. Accordingly, special attention should be paid to the movements of moored ship because surge force and yaw moment changes in the opposite direction before and after condition of ship's beam. However, when the container ship passes the larger moored ship in reverse, peak point stood out on the passing ship at the beginning of ship-to-ship interaction and attraction force on the passing ship occurred steadily during 1L(length overall of passing ship) interval at a point of beam. In addition, as the lateral distance between the hull of two ships decreases less than 2B(breadth of passing ship), interaction forces on the passing ship at the beginning are sharply increase.

• Earthquakes and Structures
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• v.27 no.2
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• pp.143-154
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• 2024

Friction pendulums typically suffer from poor uplift-restraining. To improve the uplift-restraining and enhance the energy dissipation capacity, this article proposed a composite isolation device based on electromagnetic forces. The device was constructed based on a remote control system to achieve semi-active control of the composite isolation device. This article introduces the theory and design of an electromagnetic chuck-friction pendulum system (ECFPS) and derives the theoretical equation for the ECFPS based on Maxwell's electromagnetic attraction equation to construct the proposed model. By conducting 1:3 scale tests on the electromagnetic device, the gaps between the practical, theoretical, and simulation results were analyzed, and the accuracy and effectiveness of the theoretical equation for the ECFPS were investigated. The hysteresis and uplift-restraining performance of ECFPS were analyzed by adjusting the displacement amplitude, vertical load, and input current of the simulation model. The data obtained from the scale test were consistent with the theoretical and simulated data. Notably, the hysteresis area of the ECFPS was 35.11% larger than that of a conventional friction pendulum. Lastly, a six-story planar frame structure was established through SAP2000 for a time history analysis. The isolation performances of ECFPS and FPS were compared. The results revealed that, under horizontal seismic action, the horizontal seismic response of the bottom layer of the ECFPS isolation structure is greater than that of the FPS, the horizontal vibration response of the top layer of the ECFPS isolation structure is smaller than that of the FPS, and the axial force at the bottom of the columns of the ECFPS isolation structure is smaller than that of the FPS isolation structure. Therefore, the reliable uplift-restraining performance is facilitated by the electromagnetic force generated by the device.

• Korea-Australia Rheology Journal
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• v.15 no.1
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• pp.1-7
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• 2003

A new method is introduced to build up organic/organic multilayer films composed of cationic poly(allylamine hydrochloride) (PAH) and negatively charged poly (sodium 4-styrenesulfonate) (PSS) using the spinning process. The adsorption process is governed by both the viscous force induced by fast solvent elimination and the electrostatic interaction between oppositely charged species. On the other hand, the centrifugal and air shear forces applied by the spinning process significantly enhances desorption of weakly bound polyelectrolyte chains and also induce the planarization of the adsorbed polyelectrolyte layer. The film thickness per bilayer adsorbed by the conventional dipping process and the spinning process was found to be about 4 ${\AA}$ and 24 ${\AA}$, respectively. The surface of the multilayer films prepared with the spinning process is quite homogeneous and smooth. Also, a new approach to create multilayer ultrathin films with well-defined micropatterns in a short process time is Introduced. To achieve such micropatterns with high line resolution in organic multilayer films, microfluidic channels were combined with the convective self-assembly process employing both hydrogen bonding and electrostatic intermolecular interactions. The channels were initially filled with polymer solution by capillary pressure and the residual solution was then removed by the .spinning process.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.1228-1231
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• 2005

This paper reports about the development of scanning probe microscopy (SPM) tip with multi-walled carbon nanotube (MWNT). For making a carbon nanotube (CNT) modified tips, AC electric field which causes the dielectrophoresis was used for alignment and deposition of CNTs to the metal coated SPM tip. By dropping the MWNT solution and applying an electric field between an SPM tip and an electrode, MWNTs which were dispersed into a diluted solution were directly assembled onto the apex of the SPM tips due to the attraction by the dielectrophoretic force. In this paper, we investigate experimental conditions about the alignment of the CNT to tip axis according to the change of the angle between a tip and an electrode. Experimental results are presented, and then fabricated CNT tips are showed and measurement results for 15nm gold particles are compared with that of the conventional silicon tip.

• Journal of The Korean Association For Science Education
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• v.8 no.1
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• pp.57-72
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• 1988

It is very important for a teacher to know what his students know and what they do not; however, it seems not true for the most Korean secondary school science techers. This study tried to find students' misconception Newton's third law and the sources of the misconceptions. The researcher examined 609 students from middle schools, high schools, and college. In this study, students' understanding on Newton's third law were examined by school level, sex, stream (science and liberal arts), and departments. The following results were obtained by this study. 1. Students' understanding seemed to be improved continuously from middle school to university; however, their misconception (the most frequent incorrect selection of options of the test items) did not changed very much. 2. Students' answers were significantly affected by size of objects, existence of physical contact and the existence of life in the objects. 3. The answer were significantly affected by the source of attraction. 4. The answer to Newton's third law were affected by the magnitude of potential force which the target bodies have, state of motion, velocity, weight, friction and acceleration. This study could show the sources of the misconception on Newton's third law. The identified sources could be very useful for designing an instruction to teach Newton's third law in schools and universities.