• Tunnel and Underground Space
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• v.21 no.3
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• pp.151-163
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• 2011

The LCM test is one of the most powerful and reliable methods for designing the disc cutter and for predicting the TBM (Tunnel Boring Machine) performance. It has an advantage to predict the actual load on disc cutter from the laboratory test on the real-size large rock samples, however, it also has a disadvantage to transport and/or prepare the large rock samples and to need an extra cost for experiment. Moreover it is not easy to execute the test for jointed rock mass, and sometimes the design model estimated from the test can not be applied to the real design of disc cutter. In order to break this critical point, lots of numerical studies have been performed. PFC2D can simulate crack propagation and rock fragmentation effectively, because it is useful in particle flow analysis. Consequently, in this study, the PFC2D has been adopted for numerical analysis on cutting power of disc cutter according to the different angle of joint, the different direction of joint, and the different space of joint with jointed rock mass models. From the numerical analyses, it was concluded that the bigger cutting power of disc cutter was needed for reverse cutting direction to joint rather than for forward direction, and the cutting power of disc cutter was increased with decreasing the dip angle of joint and decreasing the space of joints in reverse cutting direction. The more precise numerical model for disc cutter can be developed from comparison between the numerical results and LCM test results, and the resonable guideline is expected for prediction of TBM performance and disc cutter.

• The Journal of Korean Society for School & Community Health Education
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• v.1 no.2
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• pp.105-125
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• 2000

The purpose of this study was to examine the influence of school safety accident on teacher's normal educational activities and to seek some desirable ways to cope with it. The subjects in this study were 351 class teachers randomly selected from Seoul and Kyonggi Province and surveyed from April through July, 2000. The conclusions were as follows; 1. Actual Condition of School Safety Accident 1) Approximately many teachers investigated had had an experience to suffer safety accident. Safety accident occurred most during break or class, but there was a significant difference according to service area. 2) Safety accident took place most in playground, and the most common cause was student's own carelessness, and the most widely occurred accident type was an injury. But there was no significant difference caused by the general characteristics of the teachers. 2. Influence of Safety Accident On Teacher's Educational Activities. 1) The largest reason they offered safety education was to ensure student safety. The greatest number of them had an opinion they would consider changing or giving up a planned normal educational activity if they recognized any possibilities of safety accident. There was a significant difference in this point according to gender and career. 2) They worried about possible safety accident most during field study, but there was a significant difference according to gender or presence or absence of safety accident experience. 3) The general characteristics of teacher produced a significant difference to an experience of avoiding educational activity due to psychological withdrawal, but safety accident experience didn't make any difference. 3. Minimization of Teacher Damage or Loss from Safety Accident. 1) The dominant opinion about teacher's small mistake for any occurrence of safety accident was that the responsibility should be escaped to maintain teacher's authority. For severe mistake, however, there were two different opinions at the same percentage: one was being exempted and the other was taking civil liability. 2) Establishing teacher insurance was preferred as a way to minimize teacher's economic loss from safety accident, but there was a significant difference according to gender. 3) The dominant opinion about the payment of insurance premium for safety accident was that it should be paid from school operating expenses.

• The Bulletin of The Korean Astronomical Society
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• v.43 no.1
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• pp.59.4-60
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• 2018

To investigate the impact of the high-redshift quasars on cosmic reionization, the faint end slope of the quasars luminosity function has to be determined precisely. More quasars with low luminosity are needed to constrain the contribution to reionization in the early universe. However, finding these quasars has been regarded as tough process owing to the improper shallow depth of imaging data. In recent days, the release data of Subaru Hyper Suprime-Cam (HSC) Strategic Program survey which provide the deep images reaching ~ 25 mag facilitates searching the faint quasars candidates. To find faint quasar candidates in ELAIS-N1 field, along with the HSC data, two near-infrared (NIR) data sets also be used : The Infrared Medium-deep Survey (IMS) and The UKIRT Infrared Deep Sky Survey (UKIDSS) - Deep Extragalactic Survey (DXS). Quasar candidates selected from the multi-band color cut were observed by the SED camera for QUasars in EArly uNiverse (SQUEAN) instrument. To trace the redshifted Lyman break efficiently, appropriate medium bands comparable to targeted redshift range are chosen. The most reliable quasar candidates are finally determined through SED fitting. Using this less luminous quasars candidates, we can speculate the relation between the quasar growth and the host galaxy unbiasedly and estimate the contribution to the cosmic reionization.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.21 no.4
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• pp.362-370
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• 2010

In this paper, a compact RF Front-end module for Wireless Fidelity(Wi-Fi) and Worldwide Interoperability for Microwave Access(WiMAX) applications is realized by low temperature co-fired ceramic(LTCC) technology. The RF Front-end module is composed of three LTCC band-pass filters, a Film Bulk Acoustic Resonator(FBAR) filter, fully embedded matching circuits, an SPDT switch for mode selection, an SPDT switch for Tx/Rx selection, and an SP4T switch for band selection. The parasitic elements of 0.2~0.3 pF are generated by the structure of stacking in the top pad pattern for DC block capacitor of SPDT switch for mode selection. These kinds of parasitic elements break the matching characteristic, and thus, the overall electrical performance of the module is degraded. In order to compensate it, we insert a parallel lumped-element inductor on capacitor pad pattern for DC block, so that we obtain the optimized performance of the RF Front-end module. The fabricated RF front-end module has 12 layers including three inner grounds and it occupies less than $6.0mm{\times}6.0mm{\times}0.728mm$.

• Korean Journal of Community Nutrition
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• v.10 no.2
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• pp.174-182
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• 2005

To investigate how the beverage consumption of middle school students are different in some respects; favorite kinds, drinking time and so on. 579 middle school students in Jeonju were participated in this study. This study shows the frequency of drinking beverage and the correlation between the frequency and the various factors to have effects on the frequency. The students usually drink water 8.55 times, milk or yogurt 3.01 times, sport beverage 2.13 times, soft drink 1.93 times, and fruit and vegetable juice 1.85 times for one week. The boy students prefer more soft or sport drink to the girl students. However the drinking of other beverages such as water, milk, juice, traditional ones don't have any meaning-ful differences between the boys and the girls. The students drink water mostly when they have meals. And the second consuming beverage is milk at table. It explains the students who drink more milk than water with bread. There is a big difference according to their excercise frequency. The students who excercise regularly or excercise over 3 hours drink more soft or sport drink and milk or yogurt than the students who exercise less than 1 hour. The beverages are firstly needed during the exercise because they sweat. And the second beverage time is when they have snacks and when they take a break. It should be suggested that nutrition education targeted to middle school students and their parents should encourage limited consumption of soft drinks. Therefore, policies that limit students' access to soft drinks at schools should be promoted.

• The Journal of the Korea Contents Association
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• v.12 no.1
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• pp.91-102
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• 2012

Generally today's culture and the arts industry has been focusing more on economic value than the arts. Therefore this paper will elucidate the meaning of the culture and the arts can be a break though which can only include commercial and economic values but transcend its values ultimately. First of all, this paper will suggest an advanced 3D stereoscopic images by analysis of examples and environments of realistic media arts. Looking into the changes of related technologies and market environments, the motion-recognition technology, as seem in SF film "Minority report", has become a feasible technology. In the past, 3D stereoscopic images were shown in the theme park theatre and exhibition halls for group viewing. but recent 3D TV and display devices have changed those environments to personal. Since domestic researches of realistic media art has been little, this paper will analyze them respecting to three broad classifications. The results are : Firstly, in CAVE method, more impact capabilities of spectators are expected that they can manipulate interactive interfaces freely and the physical movements of spectators can operate interactively. Secondly, inter-network communications and expansion of viewers' perceptions are predicted by way of HMD method, sensor suites and communication equipments. Thirdly, combinations of HMD and motion tracking utilization is foreseen. With the convergent usages of these three features, we can prospect the possibilities of interactive 4D that spectators wearing 3D stereoscopic display devices can experience and make their own 3D stereoscopic images actively at the point of their views.

• Journal of the Korea Institute of Building Construction
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• v.10 no.5
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• pp.55-67
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• 2010

The main purpose of this study is to develop a system and data model extracted from the TO-BE process model of rental apartments to promote information exchange based on knowledge obtained through maintenance status analysis. Currently, it is difficult to find examples suggesting a data model through a process analysis of maintenance in rental apartments. Thus, this study intends to suggest a process as well as a data model to promote the development of a maintenance system for rental apartments by using building management knowledge, utilization of standardized tools, and existing FM (Facility Management) techniques to break through limitations in actual application. Ultimately, this study aims to show examples of document-oriented analysis and information technology for middle managers in charge of the maintenance of rental apartments, as well as work analysts developing the maintenance system. In further research beyond this study, complex issues on the maintenance of rental apartments, legal restrictions on customary practices of maintenance activities, effects of the scales of maintenance practices, requirements to perform maintenance activities, evaluation on the status of maintenance, life cycle cost and risks will be investigated.

• Explosives and Blasting
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• v.22 no.3
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• pp.57-64
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• 2004

There are two major types of underwater blasting at Korea, bridges and harbor construction work. Pier blasting for lay the foundation bridges construction is used dry excavation working (drilling and charging) after pump out water and then fire pump in water that is same as bench blasting. In contrast, underwater blasting for harbor construction and increase of harbor load depth is used to barge with digging equipment that is in oder to drilling on the surface and blasting work(charge, hook-up) under water. Thus, there are need to special concern such as charge method and hook-up method different from tunnel blasting work and bench blasting work. If do not use special concern breaks out dead pressure and mis fire because of there are so many difficult condition such as water pressure, obstruct field of vision. In this study underwater blasting at Busan Harbor Construction have consider with special concern that is plastic pipe charge method used to MegaMITE I and specialized buoy hook- up method make far initial system detonate on the surface used to TLD. The results is designed blast pattern charge per delay effect an inspection of verify between predict velocity and measure velocity. minimized break out mis fire consideration charge method, hook up method. According to result best underwater blasting design is 105mm drilling dia, MeGAMITE II, HiNLL Plus(non electric detonator).

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.27 no.3
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• pp.393-400
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• 2009

Recently demand for the 3D modeling technology to reconstruct real world is getting increasing. However, existing geospatial data are mainly based on the 2D space. In addition, most of the geospatial data provide geometric information only. In consequence, there are limits in various applications to utilize information from those data and to reconstruct the real world in 3D space. Therefore, it is required to develop efficient 3D mapping methodology and data for- mat to establish geospatial database. Especially digital elevation model(DEM) is one of the essential geospatial data, however, DEM provides only spatially distributed 3D coordinates of the natural and artificial surfaces. Moreover, most of DEMs are generated without considering terrain properties such as surface roughness, terrain type, spatial resolution, feature and so on. This paper suggests adaptive and flexible geospatial data format that has possibility to include various information such as terrain characteristics, multiple resolutions, interpolation methods, break line information, model keypoints, and other physical property. The study area was categorized into mountainous area, gently rolling area, and flat area by taking the terrain characteristics into account with respect to terrain roughness. Different resolutions and interpolation methods were applied to each area. Finally, a 3D digital map derived from aerial photographs was integrated with the geospatial data and visualized.

• Horticultural Science & Technology
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• v.32 no.3
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• pp.296-302
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• 2014

The foliage of variegated Solomon's seal is excellent in cut flower arrangements. However, it has a restricted marketing period because the harvesting is limited in spring and summer. The increased interest requires the year-round production, thus techniques for dormancy breaking and forcing without low temperature treatment is needed. Therefore, experiments were conducted to d etermine whether gibberellic acid (GA) could break dormancy in variegated Solomon's seal. Thes prouting of dormant bud did not occur throughout the experiment when $GA_3$ $400mg{\cdot}L^{-1}$ was applied to dormant rhizomes as a soil drench. However, when plants were treated with a GA drench after scratch with razor blade or were given direct injection of GA, percent sprouting was increased up to 100 or 83.3%, respectively. However, because treatments with razor or syringe may damage internal organs, we tested another method, scarifying the rhizomes with sodium hypochlorite (NaOCl). Rhizome scarification with 4% NaOCl for 6 or 24 hours followed by drench of $GA_3$ $400mg{\cdot}L^{-1}$ increased the dormancy breaking percentage to 70 or 86.7%, respectively. Moreover, scarified and GA-treated rhizomes produced more leaves than untreated or GA-soil drenched plants in the glasshouse. These results showed the possibility of year-round production of variegated Solomon's seal foliage with rhizome scarification and GA treatments.