• Journal of Soil and Groundwater Environment
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• v.20 no.3
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• pp.41-50
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• 2015

Hydrogeologic environment of the Mega City such as Seoul, suffers from rapid changes caused by urbanization, construction of underground subway or buildings, and contaminant loading by diverse anthropogenic activities. Understanding the present condition of groundwater environment and water budget is necessary to prevent natural and manmade disasters and to prepare for sustainable water resource management of urban environment. In this study, regional groundwater flow and water budget status of Seoul was analyzed using numerical simulation. Modeling result indicated that groundwater level distribution of Seoul generally followed the topography, but the significant decreases in groundwater level were observed around the subway network. Steady-state water balance analysis showed groundwater recharge by rainfall and leakage from the water supply network was about 550,495 m³/day. Surface water inflow and baseflow rate via Han River and major streams accounted for 799,689 m³/day and 1,103,906 m³/day, respectively. Groundwater usage was 60,945 m³/day, and the total groundwater leakage along the subway lines amounted to 114,746 m³/day. Modeling results revealed that the subway could decrease net groundwater baseflow by 40%. Our study result demonstrated that the subway system can have a significant influence on the groundwater environment of Seoul.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.34 no.1
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• pp.1-10
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• 2016

Seoul, a mega city, contains many features of the modern city. When the disaster or emergency occurs in Seoul, the place for shelter is required for evacuation urgently. There are currently the numbers of shelters in Seoul City, which can hold the twice more capacity of population of Seoul. However, the population distribution fluctuation in the day and the night needs to be considered. Therefore, in order to analyze the actual capacity of shelter, it is necessary to consider the dynamic characteristics of population distribution in the metropolitan area. In the study, the substantial accessibility and the capacity of shelters in Seoul were analyzed by the floating population data of the metropolitan area. The accessibility of shelter was investigated through a network analysis that includes the pedestrian road data, while the capacity of shelter was analyzed by the local differences of daytime population distributions. Finally it was possible to identify the vulnerable areas on the basis of the distribution of shelter in the region.

• Transactions of the Society of Information Storage Systems
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• v.1 no.2
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• pp.155-160
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• 2005

In this paper, the channel decoder promising reliable data retrieving in noisy holographic channel has been developed for holographic WORM(write once read many) system. It covers various DSP(digital signal processing) blocks, such as align mark detector, adaptive channel equalizer, modulation decoder and ECC(error correction code) decoder. The specific schemes of DSP are designed to reduce the effect of noises in holographic WORM(H-WORM) system, particularly in prototype of DAEWOO electronics(DEPROTO). For real time data retrieving, the channel decoder is redesigned for FPGA(field programmable gate array) based hardware, where DSP blocks calculate in parallel sense with memory buffers between blocks and controllers for driving peripherals of FPGA. As an input source of the experiments, MPEG2 TS(transport stream) data was used and recorded to DEPROTO system. During retrieving, the CCD(charge coupled device), capturing device of DEPROTO, detects retrieved images and transmits signals of them to the FPGA of hardware channel decoder. Finally, the output data stream of the channel decoder was transferred to the MPEG decoding board for monitoring video signals. The experimental results showed the error corrected BER(bit error rate) of less than $10^{-9}$, from the raw BER of DEPROTO, about $10^{-3}$. With the developed hardware channel decoder, the real-time video demonstration was possible during the experiments. The operating clock of the FPGA was 60 MHz, of which speed was capable of decoding up to 120 mega channel bits per sec.

• Restorative Dentistry and Endodontics
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• v.28 no.1
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• pp.41-49
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• 2003

There are increasing usage of Nickel-Titanium rotary files in modern clinical endodontic treatment because it is effective and faster than hand filing due to reduced step. This study was conducted to evaluate the effect of canal preparations using 3 different rotary Nickel-Titanium files that has different cross sectional shape and taper on the maintenance of canal curvature. Simulated resin block were instrumented with Profile(Dentsply, USA), GT rotary files(Dentsply, USA), Hero 642(Micro-Mega France), and Pro-Taper(Dentsply, USA). The image of Pre-instrumentation and Post-instrumentation were acquired using digital camera and overspreaded in the computer. Then the total differences of canal diameter, deviation at the outer portion of curvature, deviation at the inner portion of curvature, movement of center of the canal and the centering ratio at the pre-determined level from the apex were measured. Results were statistically analyzed by means of ANOVA, followed by Scheffe test at a significance level of 0.05. The results were as follows； 1. Deviation at the outer portion of curvature, deviation at the inner portion of curvature were showed largest in Pro-Taper so also did in the total differences of canal diameter(p＜0.05). 2. All the groups showed movements of center Profile combined with GT rotary files and Hero 642 has no difference but Pro-Taper showed the most deviation(p＜0.05). 3. At the 1, 2, 3mm level from the apex movements of center directed toward the outer portion of curvature, but in 4, 5 mm level directed toward the inner portion of curvature(p＜0.05). As a results of this study, it could be concluded that combined use of other Nickel-Titanium rotary files is strongly recommended when use Pro-Taper file because it could be remove too much canal structure and also made more deviation of canal curvature than others.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.21 no.4
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• pp.126-136
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• 2013

Aircraft accidents these days, following the mega sizing trend of the aircraft, result in enormous losses of human lives apart from those of property, which cannot be replaced by any means. As most recently, in April 20, 2012, a Boeing 737 passenger plane departed Karachi on an augural flight to Islamabad, Pakistan, crashed close to an express highway on final approach, all 121 passengers and 6 crew members were killed. As such a large number of fatalities have been recorded in aircraft accidents while accident investigation results show that more than 95% of aircraft accidents are now survivable. There are three basic stages in surviving the aircraft accident: surviving the crash impact, the evacuation process and the hostile post evacuation environmental elements. These stages require the cabin crew's expeditious and appropriate actions on the basis of systematic and thorough cabin safety training in order to increase occupants' survivability, along with the passengers' preparedness. In this aspect, this paper examines the issues acting as the impediments to the passenger survival in inflight emergency situations, that are the deficiencies with cabin crew safety training, related performances and the shortcomings in passengers' knowledge on inflight safety information, leading to their inappropriate responses to emergency situations. These issues are analyzed and the root causes are identified, suggesting the resolving countermeasures.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.21 no.4
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• pp.77-89
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• 2013

The purpose of this study is to anticipate the air travel demands over the period of 164 months, from January 1997 to August 2010 using ARIMA-Intervention modeling on the selected sample data. The sample data is composed of the number of the passengers who in the domestic route for Jeju route. In the analysis work of this study, the past events which are assumed to have affected the demands for the air travel routes to Jeju in different periods were used as the intervention variables. The impacts of such variables were reflected in the presupposed demand. The intervention variables used in this study are, respectively, the World Cup event in 2002 (from May to June), 2003 SARS outbreak (from April to May), Tsunami in January 2005, and the influenza outbreak from October to December 2009. The result of the above mentioned analysis revealed that the negative intervention events, like a global outbreak of an epidemic did have negative impact on the air travel demands in a risk aversion by the users of the aviation services. However, in case of the negative intervention events in limited area, where there are possible substituting destinations for the tourists, the impact was positive in terms of the air travel demands for substituting destinations due to the rational expectation of the users as they searched for other options. Also in this study, it was discovered that there is not a binding correlation between a nation wide mega-event, such as the World Cup games in 2002, and the increased air travel demands over a short-term period.

• Applied Microscopy
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• v.42 no.2
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• pp.105-109
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• 2012

Electron tomography (ET) of biological specimens is performed from a series of images obtained over a range of tilt angles in a transmission electron microscope. When using the high voltage electron microscope (HVEM), various noises appear in EM images acquired from thick sections by high voltage electron beam. In order to obtain an adequate result in electron tomograms that allow visualization of rather complex and mega-cellular structure such as brain tissue, it is necessary to remove the noise in each original tilt images of thick section. Using band-pass filtering of original tilt images, the filtered images are obtained and used to assemble a reconstructed tomogram. The qualified 3D tomogram from filtered images results in a considerable reduction of the noises compared to conventional tomogram. In conclusion, this study suggests that band-pass filtering is effective to improve the brightness and intensity of HVEM produced tomograms acquired from micron-thick sections of biological specimens.

• Journal of Fashion Business
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• v.20 no.2
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• pp.32-45
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• 2016

Outdoor wear, which is typically worn for outdoor activities, has become a style that is worn on a daily basis, much like ordinary clothes, through recent megatrends. There are new approaches to outdoor wear with high-fashion brands and designers recently taking part in the trend. This indicates that outdoor wear has already reached high-fashion, no longer making it just a megatrend or daily fashion. Therefore this study aims to find new features of outdoor looks and designs, through the latest women's ready-to-wear collections from 2014 to 2015. The study will focus on mega collections, which have shown many new approaches, and searches to change and development the present day outdoor look design, by using the word 'outdoor look' which is explained as a 'style' in a broad sense, and using it a general term of 'clothes'. High fashion brands have pursued changing their styles by mixing their designs with outdoor wear's variety, functionality and details; attempting new approaches and challenges. Due to these updated changes, the outdoor look is thriving and becoming part of high fashion. Looking forward to future new approaches and the development of the outdoor look will help catapult this type of 'style' into a new category of modern fashion.

• Korean Journal of Construction Engineering and Management
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• v.14 no.4
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• pp.164-171
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• 2013

In urban planning, road facility is used not only for the transportation purpose but also for the utility line space purpose such as electrical, gas, tele communication, heating, water, sewer, and so on. However, since these utilities are built by many different groups, it becomes very difficult to communicate each other. Delay in one party can cause another party's schedule delay but they don't commuicate often. Also, some delay in utility work can cause frequent pavement cut. And, this will impact on construction cost, schedule delay, low quality, user complain and cost. This study developed spatiotemporal decision model to prevent prequent utility cut for mega project such as new urban development project. In addition, this study developed utility cut management system to manage utility cut schedule under pavement. Finally, developed system was applied to new urban development project and verified there effectiveness.

• The Journal of Advanced Prosthodontics
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• v.11 no.6
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• pp.350-357
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• 2019

PURPOSE. This study aims to evaluate the loosening torque on the implant fixture, and to assess the accuracy of difference electronic torque drivers. MATERIALS AND METHODS. Three electronic torque drivers were used to measure the loosening torque on the implant system (AnyOne; MegaGen). The implant fixtures were divided among the 3 electronic torque driver types (W&H, SAESHIN, and NSK group) and 9 for each group. The screws were fastened at the implant fixture by three electronic torque drivers using the tightening torques recommended by the manufacturers of the drivers. After 10 minutes, the screws were again fastened at the implant fixture with equal torque. Then, the loosening torques were measured with an MGT12 torque gauge (MARK-10, Inc.). This measurement procedure was repeated 10 times under loosening torques of 15 Ncm, 25 Ncm, and 35 Ncm. In the statistical analysis, all values of loosening torque were analyzed with the one-way ANOVA and Kruskal-Wallis test (α=.05) for comparative evaluation. RESULTS. There were significant inter-group differences at loosening torques of 15 Ncm and 25 Ncm (P<.05). The accuracy of the NSK driver was the highest, followed by SAESHIN and W&H. There was no significant difference between NSK and W&H at 35 Ncm (P>.05). The SAESHIN driver showed the closest loosening torque at 35 Ncm. CONCLUSION. The most accurate loosening torques were SAESHIN at 35 Ncm, and NSK at 15 Ncm and 25 Ncm. Since the loosening torque may vary depending on the tightening torques and electronic torque drivers, periodic calibration of the electronic torque driver is recommended.