• Journal of Technologic Dentistry
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• v.8 no.1
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• pp.31-36
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• 1986

This treatise suggests the effective method for the dental laboratory technology teaching plan. It will present concrete practical steps for and audio-visual dental laboratory technology education approach. It will also help students to understand the dental laboratory theory and practice learned in the class and make use of it greatly in the field work. As follows: 1. Instructor should teach interestingly basic dental laboratory technology theory with illustrations and figures on the teaching method. 2. In practical traing class, instructor should teach every step, using audio-visual materials such as slides and video tapes/Instructor and his assist and should show an example to the students. 3. Instructor should make a standard and train the studtnes repeatedly until they come up to it. 4. Students should be skilled in every case through field work during their spare time and vacation. 5. Instructor should also teach job moral and manner to the students so that they can be adapted themselves to the social activities and be successful dental laboratory technician after graduation.

• Journal of Information Processing Systems
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• v.11 no.2
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• pp.205-228
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• 2015

In this paper, we present a virtual laboratory platform (VLP) baptized Mercury allowing students to make practical work (PW) on different aspects of mobile wireless sensor networks (WSNs). Our choice of WSNs is motivated mainly by the use of real experiments needed in most courses about WSNs. These experiments require an expensive investment and a lot of nodes in the classroom. To illustrate our study, we propose a course related to energy efficient and safe weighted clustering algorithm. This algorithm which is coupled with suitable routing protocols, aims to maintain stable clustering structure, to prevent most routing attacks on sensor networks, to guaranty energy saving in order to extend the lifespan of the network. It also offers a better performance in terms of the number of re-affiliations. The platform presented here aims at showing the feasibility, the flexibility and the reduced cost of such a realization. We demonstrate the performance of the proposed algorithms that contribute to the familiarization of the learners in the field of WSNs.

• 대한공업교육학회지
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• v.38 no.1
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• pp.125-143
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• 2013

The purpose of this study was to investigate the current Status and practical use of technology laboratory at the junior high school in Chungbuk Province in order to give some suggestions on hands-on activities for technology education. First, concerning present actual conditions of technology laboratory, There was a large disparity between the urban and rural schools in the possession of a technology laboratory, as the rate of the schools equipped with the rooms respectively stood at 69.84 percent and 33.38 percent in the urban and rural regions. By the type of foundation, every national school, 86.24 percent of the public schools and 37.50 percent of the private schools were equipped with the technology laboratory. By school size, 35.59 of the schools with fewer than 10 classes, 62.11 percent of the schools with 10 to fewer than 30 classes and 85.71 percent of the schools with 31 classes or more were in possession of the laboratory. Thus, the type of foundation and school size made differences to that. As a result of asking the schools without the laboratory about the reason, as many as 88.52 percent had been equipped with the laboratory in the past but converted them into spaces for another purpose. When the schools that had no such laboratory were asked a question whether they had any plans to install a technology laboratory, just five schools(8.19%) had that plan. Second, as for the practical use of the technology laboratory, for what the rooms were actually used was asked, and most of the schools made use of them as Comprehensive General laboratory. As to the size of the rooms, each of the rooms was as large as a classroom($66m^2$) in 62.12 percent of the schools, and their region, type of foundation and student gender made little significant differences to that. Regarding the time for utilizing the laboratory, the majority of the schools used the laboratory approximately once or twice a year, and their region, type of foundation, student gender and school size made few distinctive differences to that. In terms of budget for practice in the rooms, the largest number of the schools that accounted for 36.36 percent earmarked three thousand won to less than five thousand won per student.

• Journal of Technologic Dentistry
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• v.34 no.4
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• pp.413-421
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• 2012

Purpose: The purpose of this study is to investigate the improvement measure of dental technician practical examination. Methods: A survey was performed on 111 dental technicians who were self-written questionnaire. The results were analyzed by SPSS 12.0. The collected data was analyzed by frequency and chi-square test. Results: Questions most necessary work tools with the articulator was the highest with 55.9%, Electric wax carver(16.2%), heating clear(14.4%), CAD/CAM program(9.0%) was in the order. The need for additional practical test in response to actions included maxillary and mandibular comments occlusal work that you have to wax up the highest rate of 63.8%. Items most in need of improvement was strengthen of clinically oriented(48.0%), separation of written and practical(14.6%), control the degree of difficulty(11.4%) were the next order. Conclusion: Based on the results of this study, the current dental technician did not show major problems in the practical test. However, clinicians should be strengthened mainly. To do this, the use of the articulator is essential.

• Journal of Technologic Dentistry
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• v.38 no.4
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• pp.315-325
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• 2016

Purpose: This study investigated perception and plan of dental technologists regarding the old age and retirement for them to enjoy stable old age. Methods: Dental technologists working in Seoul, Incheon, and Gyeonggido were asked to fill out a self-administered questionnaire, and a total of 200 copies were used for analysis. The collected data were statistically analyzed by using SPSS 22.0(Statistical Package for Social Sciences. Chicago, IL, USA) (a=0.05). In order to compare perception toward old age preparation among the subjects, a Chi-square test was performed, and, to investigate the level of preparedness for old age according to general characteristics, t-test was performed. Results: In the analysis of the old age preparedness by age, there was a significant difference in financial preparation, Asset identification, use of retiring allowance, information gathering, senior town home, and stability (p<0.05). To the questions regarding perception toward retirement, the majority of the subjects (60.5%) answered they had thought about retirement, and many (23.9%) of them attributed the reason to job stress (23.9%). Regarding old age preparedness according to workplace, there was a significant difference in use of retirement allowance and education for old age preparedness between general dental laboratories and general hospitals (p<0.05). Conclusion: It is believed that, for preparation of dental technologists for stable old age, in addition to their personal effort, it is important to provide social support and practical measures to ensure welfare and retirement.

• Speech Sciences
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• v.8 no.1
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• pp.159-165
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• 2001

In this paper, we make an experiment on speech recognition systems with barging-in and non-barging-in utterances. Barging-in capability, with which we can say voice commands while voice announcement is coming out, is one of the important elements for practical speech recognition systems. Barging-in capability can be realized by echo cancellation techniques based on the LMS (least-mean-square) algorithm. We use three kinds of telephone interface boards with barging-in capability, which are respectively made by Dialogic Company, Natural MicroSystems Company and Korea Telecom. Speech database was made using these three kinds of boards. We make a comparative recognition experiment with this speech database.

• Journal of Information Display
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• v.3 no.1
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• pp.27-34
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• 2002

POS446M and POS430Ti alloys were investigated for application to a Flatron rail instead of conventional 28 wt%Cr alloy in order to reduce material costs. It was found that the permeability decrement of materials could be successfully minimized by proper heat treatment, and that the beam landing drift of the Flatron was not overly affected by the permeability of materials. In addition, the Flatron manufacturing process using POS430Ti was also stabilized without glass cracking by the application of the modified process conditions, which were optimized through the design of the experiment method.

• Journal of the Korean Ceramic Society
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• v.56 no.4
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• pp.331-339
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• 2019

While high-temperature ceramic composites consisting of carbides, borides, and nitrides, the so-called ultra-high-temperature ceramics (UHTCs), have been commonly produced through solid-state sintering, melt-solidification is an alternative method for their manufacture. As many UHTCs are binary or ternary eutectic systems, they can be melted and solidified at a relatively low temperature via a eutectic reaction. The microstructure of the eutectic composites is typically rod-like or lamellar, as determined by the volume fraction of the second phase. Directional solidification can help fabricate more sophisticated UHTCs with highly aligned textures. This review describes the fabrication of UHTCs through the eutectic reaction and explains their mechanical properties. The use of melt-solidification has been limited to small specimens; however, the recently developed laser technology can melt large-sized UHTCs, suggesting their potential for practical applications. An example of laser melt-solidification of a eutectic ceramic composite is demonstrated.

• Geomechanics and Engineering
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• v.8 no.3
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• pp.461-476
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• 2015

Rankine's theory of earth pressure cannot be directly employed to c-${\phi}$ soils backfill with a sloping ground subjected to complex loadings. In this paper, an analytical solution for active earth pressures on retaining structures of cohesive backfill with an inclined surface subjected to surcharge, pore water pressure and seismic loadings, are derived on the basis of the lower-bound theorem of limit analysis combined with Rankine's earth pressure theory and the Mohr-Coulomb yield criterion. The generalized active earth pressure coefficients (dimensionless total active thrusts) are presented for use in comprehensive design charts which eliminate the need for tedious and cumbersome graphical diagram process. Charts are developed for rigid earth retaining structures under complex environmental loadings such as the surcharge, pore water pressure and seismic inertia force. An example is presented to illustrate the practical application for the proposed coefficient charts.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2011.11a
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• pp.295-296
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• 2011

The DRM+ is the newest digital radio standard for in-band environment. Although various state of the art technologies are adopted, the performance evaluation information is not sufficient. It is hard that many countries and stations considering the DRM+ as their digital radio standard check the performance of DRM+. To evaluate the performance of the DRM+ system, this paper depicts the laboratory trial results of DRM+ standard. In the laboratory trial, the rack type DRM+ test bed is built. To reflect the practical broadcasting environment, various tests are executed. Many countries and stations can efficiently use these test results, which are considering converting their analog radio broadcasting to digital broadcasting.