• Journal of Technologic Dentistry
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• v.38 no.2
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• pp.57-62
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• 2016

Purpose: The purpose of this study was to assess precision of crown prostheses that were fabricated by using 2 kinds of bur or 3 kinds of bur. Methods: The crowns were fabricated by using the first molar of the right maxillary in this study. The abutments that were prepared were scanned by using a scanner and designed by using CAD software. Based on the crown design, NC data were created with CAM software. The created NC data were used while fabricating the crown prostheses by using 5-axis milling machine. Scanning was done for the internal and external surface of the completed crown prostheses and 3-dimensional measurement was conducted for precision assessment. Results: The $RMS{\pm}SD$ value for the external surface of the crown prostheses that was fabricated by using two burs and three burs were $28.5{\pm}4.1{\mu}m$ and $19.1{\pm}2.8{\mu}m$, respectively; and the value for two burs were bigger than that for three burs with statistical significance (p<0.001). The $RMS{\pm}SD$ value for the internal surface of the crown prostheses that was fabricated by using two burs and three burs were $14.9{\pm}1.9{\mu}m$ and $13.3{\pm}2.5{\mu}m$, respectively; and the value for two burs were bigger than that for three burs but with no statistical significance. Conclusion: Based on this study, the prostheses that were fabricated by using 3 bur presented better stability compared to those that were fabricated by using 2 bur and statistically significant difference was found only in the external surface.

• Journal of Radiation Protection and Research
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• v.39 no.2
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• pp.109-117
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• 2014

Nuclear emergency planning is to plan sheltering, evacuation and iodine prophylaxis for the residents living in the area where the emergency plan is needed, the area is confirmed based on the dose assessment using the source-term through an accident analysis and the data measured from meteorological tower. In this study, the does change before and after protective measures was assessed stochastically based on the one year meteorological data in the condition of the maximum hypothetical accident which can be considered at the research reactor 'HANARO', and the optimized protective measures were derived based on the reference levels defined as a residual dose by ICRP 2007 recommendation which can be applied in a emergency exposure situation. The optimized protective measures for the HANARO in the maximum hypothetical accident were the evacuation to radius 300 m, the sheltering from 300 m to 800 m, the iodine prophylaxis only for the emergency workers under the protective measures for non emergency workers.

• The Journal of Korean Academy of Sensory Integration
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• v.15 no.1
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• pp.10-20
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• 2017

Objective : The purpose of this study was to investigate the effect of proprioceptive-vestibular based sensory integrative intervention on handwriting and fine motor function in elementary school students in grades 1 to 3. Methods : In this study, eight students in an elementary school in Busan were enrolled. The intervention was conducted twice a week from May to October, 2016, and a total of 14 intervention sessions were conducted. In order to evaluate the writing ability and the fine-motor exercise ability before and after the intervention, the fine-motor movement items of the Korean alphabet writing test and the Bruininks-Oseretsky Test of Motor Proficiency (BOTMP) evaluation were used. Results : There was a statistically significant difference between the total scores of consonant writing and the Korean alphabet writing assessment after the intervention. In BOTMP-Fine motor, the response speed items showed statistically significant difference. Visual-motor control scores increased during intervention, but the statistical significance was not found. Conclusion : Sensory integration interventions might have positive effects on elementary school students' writing skills and fine motor functions.

• Korean Journal of Construction Engineering and Management
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• v.14 no.2
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• pp.12-21
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• 2013

The purpose of this study is to determine a national construction industry's competitiveness and establish strategies to expand into overseas construction markets. To evaluate the international competitiveness of overseas construction businesses, this study were selected as the target range of international comparisons among the countries cited by ENR, Global-Insight, IMF, OECD, and Transparency International. In result the United States ranked first, followed by China $2^{nd}$, Italy$3^{rd}$, U.K.$4^{th}$, and Germany $5^{th}$, while Korea ranked $9^{th}$ overall. In particular, Korea's competitiveness in the construction infrastructures by country ranking($11^{th}$) was higher than the competency assessment results of construction companies by country, therein ranking $12^{th}$. In addition, while Korea ranks $12^{th}$ among 22 countries, $3^{rd}$ in price competitiveness, $12^{th}$ in construction competitiveness, and $19^{th}$ in design competitiveness.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.33 no.2
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• pp.521-528
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• 2013

Urban drainage systems are generally designed as open channel flow. The system, however, shows a partially surcharged flow in its body, especially at junctions or manholes. Thus, a special case of this condition needs to be explained as pressurized flow condition for designing the sewer system. This study considered the surcharged manhole flows during an unexpected rainfall event or an excess of design frequency. Overflows from surcharged manholes and urban flooding can occur from the effect of surcharged flows. Thus, sewer systems should be designed with the concept of open channel flow and pressurized flow. Also, energy losses in a manhole need to be considered. The aim of this study is to develop the numerical model which can evaluate the effect of the energy losses at the manhole. The numerical model was verified and compared with hydraulic model and SWMM. The results showed that the water depth of numerical model was in good agreement with hydraulic model at the each manhole. However, the SWMM underestimated the water depth because that model ignored the energy losses at manholes. Thus, the developed numerical model in this study could be a useful tool for the assessment of a conveyance of urban drainage system.

• Geomechanics and Engineering
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• v.9 no.5
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• pp.619-629
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• 2015

Influenced by various mining activities, fractures in rock masses have different densities, set numbers and lengths, which induce different mechanical properties and failure modes of rock masses. Therefore, precisely expressing the failure criterion of the fractured rock influenced by coal mining is significant for the support design, safety assessment and disaster prevention of underground mining engineering subjected to multiple mining activities. By adopting PFC2D particle flow simulation software, this study investigated the propagation and fractal evolution laws of the micro cracks occurring in two typical kinds of rocks under uniaxial compressive condition. Furthermore, it calculated compressive strengths of the rocks with different confining pressures and box-counting dimensions. Moreover, the quantitative relation between the box-counting dimension of the rocks and the empirical parameters m and s in Hoek-Brown strength criterion was established. Results showed that with the increase of the strain, the box-counting dimension of the rocks first increased slowly at the beginning and then exhibited an exponential increase approximately. In the case of small strains of same value, the box-counting dimensions of hard rocks were smaller than those of weak rocks, while the former increased rapidly and were larger than the latter under large strain. The results also presented that there was a negative correlation between the parameters m and s in Hoek-Brown strength criterion and the box-counting dimension of the rocks suffering from variable mining activities. In other words, as the box-counting dimensions increased, the parameters m and s decreased linearly, and their relationship could be described using first order polynomial function.

• Smart Structures and Systems
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• v.20 no.5
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• pp.549-562
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• 2017

The US railroad network carries 40% of the nation's total freight. Railroad bridges are the most critical part of the network infrastructure and, therefore, must be properly maintained for the operational safety. Railroad managers inspect bridges by measuring displacements under train crossing events to assess their structural condition and prioritize bridge management and safety decisions accordingly. The displacement of a railroad bridge under train crossings is one parameter of interest to railroad bridge owners, as it quantifies a bridge's ability to perform safely and addresses its serviceability. Railroad bridges with poor track conditions will have amplified displacements under heavy loads due to impacts between the wheels and rail joints. Under these circumstances, vehicle-track-bridge interactions could cause excessive bridge displacements, and hence, unsafe train crossings. If displacements during train crossings could be measured objectively, owners could repair or replace less safe bridges first. However, data on bridge displacements is difficult to collect in the field as a fixed point of reference is required for measurement. Accelerations can be used to estimate dynamic displacements, but to date, the pseudo-static displacements cannot be measured using reference-free sensors. This study proposes a method to estimate total transverse displacements of a railroad bridge under live train loads using acceleration and tilt data at the top of the exterior pile bent of a standard timber trestle, where train derailment due to excessive lateral movement is the main concern. Researchers used real bridge transverse displacement data under train traffic from varying bridge serviceability levels. This study explores the design of a new bridge deck-pier experimental model that simulates the vibrations of railroad bridges under traffic using a shake table for the input of train crossing data collected from the field into a laboratory model of a standard timber railroad pile bent. Reference-free sensors measured both the inclination angle and accelerations of the pile cap. Various readings are used to estimate the total displacements of the bridge using data filtering. The estimated displacements are then compared to the true responses of the model measured with displacement sensors. An average peak error of 10% and a root mean square error average of 5% resulted, concluding that this method can cost-effectively measure the total displacement of railroad bridges without a fixed reference.

• Geophysics and Geophysical Exploration
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• v.13 no.4
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• pp.336-348
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• 2010

The Single-channel seismic survey with the source of bubble pulser and drilling survey was carried out in 2008 and 2009 for the site survey of Daecheon-Wonsando area, which was a proposed area of Korea-China subsea tunnel. The goal of this study is to analyze the depth and characteristics of acoustic basement for the stability assessment and tunnel design in this proposed area through combining drilling data with this single-channel seismic data after detailed processing. For this purpose, among the data processing schemes which are usually applied to multi-channel seismic data, we applied the F-K filtering to eliminate the AC(alternating current) noise and the post-stack depth migration to produce depth section. As a result, we verified that the improved depth section could be obtained from single-channel seismic data, and the distribution and characteristics of basement could be analyzed in survey area through the combined analysis with drilling data. However, we could not interpret the detailed structures, fault and fracture zone, due to the quality of bubble pulser source and single-channel data. We expect that those detailed structures can be analyzed when higher resolution seismic data is provided. Therefore, we recommend some items for future seismic survey of subsea tunnel to obtain the high resolution seismic data.

• Geophysics and Geophysical Exploration
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• v.10 no.4
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• pp.353-360
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• 2007

We practiced fresh water injection test to identify its applibility as a method of seawater intrusion mitigation technique, and monitored the change of borehole fluid conductivity and the behavior of injected fresh water using borehole multichannel electrical conductivity monitoring and well-logging, and DC resistivity and SP monitoring at the surface. Well-logging and multichannel EC monitoring showed the decrease of fluid conductivity due to fresh water injection. We note that such an injection effect lasts more than several month which means the applibility of fresh water injection as a seawater intrusion control technique. Although SP monitoring did not show meaningful results because of weather condition during monitoring and the defects of electrodes due to long operation time, DC resistivity monitoring showed its effectiveness and applicability as a monitoring and assessment techniques of injection test by means of imaging the behavior and the front of fresh water body in terms of the increase of resistivity with reasonable resolution. In conclusion, we note that geophysical techniques can be an effective method of monitoring and evaluation of fresh water injection test, and expect that fresh water injection may be an practical method for the mitigation of seawater intrusion when applied with optimal design of injection well distribution and injection rate based on geophysical evaluation.

• Journal of Digital Convergence
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• v.16 no.7
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• pp.107-116
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• 2018

One of the key mission is to develop and prompte the use National Competency Standards, which is defined to be the systemization of competencies(knowledge, skills and attitudes) required to perform duties at the workplace by the nation for each industrial sector and level. This provides the basis for the design of training and detailed specifications for workplace assessment. To promote the data-driven service improvement, the commercial product Splunk was introduced, and has grown to become an extremely useful platform because it enables the users to search, collect, and organize data in a far more comprehensive, far less labor-intensive way than traditional databases. Leveraging Splunk's built-in data visualization and analytical features, HRD Korea have built custom tools to gain new insight and operational intelligence that organizations have never had before. This paper analyzes the NCS homepage. Concretely, applying Splunk in creating visualizations, dashboards and performing various functional and statistical analysis and structure without Web development skills. We presented practical use and implications through case studies.