• Journal of Korean Foot and Ankle Society
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• v.14 no.1
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• pp.58-65
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• 2010

Purpose: This study was performed to evaluate the clinical outcomes of operative treatment using porous hydroxyapatite for intraarticular calcaneal fracture of joint depression type. Materials and Methods: Twenty patients with intraarticular calcaneal fracture were followed up for more than 1 year. The period to union was calculated to evaluate the osteoconductivity of porous hydroxyapatite used as bone graft substitute. The measurement of Bohler angle, Gissane angle and the degree of articular surface depression was performed through preoperative and postoperative radiographs. The clinical evaluation was performed according to hindfoot score of the American Orthopaedic Foot and Ankle Society (AOFAS) and scale of the Creighton-Nebraska health foundation (CNHF). Results: Bohler angle and Gissane angle had improved significantly from preoperative average $10.4^{\circ}$, $117.8^{\circ}$ to average $22.6^{\circ}$, $113.5^{\circ}$ immediate postoperatively, and had maintained to average $21.2^{\circ}$ and $114.4^{\circ}$ at the last follow-up. The degree of articular surface depression had improved significantly from preoperative average 4.8 mm to 1.5 mm at the last follow-up. All cases achieved bone union, and the interval to union was average 12.8 weeks. AOFAS score was average 85.2 points at last follow-up. There were 7 excellent, 10 good, and 3 fair results according to the CNHF scale. Therefore, 17 cases (85%) achieved satisfactory results. Conclusion: Plate fixation using porous hydroxyapatite seems to be one of effective treatment methods for intraarticular calcaneal fracture of joint depression type, because of supporting the reduction of subtalar articulation by augmenting bony defect and facilitating bone formation. Further evaluation about long-term radiological changes and histological analysis on hydroxyapatite implantation site should be required.

• Tunnel and Underground Space
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• v.27 no.4
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• pp.230-242
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• 2017

Seismic velocities measured from in-situ tests (n=177) and through rock core samples (n=1,035) are reviewed in light of construction standards, widely used standards as a first-hand approximation of rock classification solely based on seismic velocities. In-situ down hole tests and refraction survey for soft rocks showed seismic velocities of 1,400~2,900 m/s which is faster than those specified in construction standards. For moderate~ hard rocks, in-situ down hole tests and refraction survey showed 2,300~3,800 m/s which roughly corresponds with the range specified in the construction standards. A similar trend is also observed for seismic velocities measured from rock core samples. The observed differences between construction standards and seismic velocities can be explained in two ways. If construction standards are correct the observed differences may be explained with seismic velocities affected by underlying fast velocities and also possibly with selection of intact cores for velocity measurement. Alternatively, construction standards may have intrinsic problems, namely artificial discrete boundaries between soft rocks and moderate rocks, application of foreign standards without consideration of geologic setting and lack of independent verification steps. Therefore, we suggest a carefully designed verification studies from a test site. We also suggest that care must be exercised when applying construction standards for the interpretation and accessment of rock mass properties.

• Asia pacific journal of information systems
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• v.18 no.4
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• pp.83-103
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• 2008

In the new web based learning environment which has recently emerged, a variety of new learning objectives and teaching methods suited to this learning environment have been adopted. Recently, web based project-based learning methods have received a great deal of attention from those wishing to improve learning performance. The objective of this study is to identify the impact of characteristics of communication media and instruction behavior on collaborative interaction and project performance through web based group projects. The characteristics of communication media were divided into richness, flexibility, and ease of use, and the characteristics of instruction behavior were divided into support and expression, which are independent variables. Collaborative interaction as a mediate variable, was divided into information sharing and negotiation. Project performance was the dependent variable. To verify the proposed research model empirically, an experiment was conducted in which learners participated in on-line and off-line courses with group projects. The group project was conducted virtual product development(VPD), and designed a web-site about the VPD. At the end of the project, a survey was conducted. Of the 270 students, 239 responded. The students were assigned to groups of 3 or 4 members, and represented different genders and levels of computer competence. The reliability, validity, and correlation of research variables were analyzed using SPSS 14.0, and the measurement model and the structural goodness-of-fit of the research model were verified through SEM analysis using Lisrel 8.54. We found important results as follows; First, richness and ease of use has positive impacts on each of sharing information and negotiation. This suggests that richness and ease of use are useful in sharing information which is related to the task and agreeing in opinions among group members. However, flexibility has not positive impacts on sharing information and negotiation. This implies that there is no great difference in performance of PC and information literacy of user. Second, support and expression of instructor have positive impacts on sharing information and negotiation. This indicates that instructors play an important role in encouraging learners to participate in the project and communicating with them, sharing information related to the project, making a resonable decision and finally leading them to improve a project performance. Third, collaborative interaction has a positive impact on project performance. This result shows that if the ability to share information and negotiate among students was improved then a project performance would be improved as well. Recently, in the state of revitalized web based learning, it is opportune that web-based group project is practically conducted, and the impact of characteristics of communication media and characteristics of instruction behavior on sharing information, negotiating among group members and improving a project performance is verified. On the basis of these results, we propose that forms of learning, such as web based project, could be one of solution which is to enforce interaction among learners, and ultimately improve learning performance. Moreover web-based group project is able to make up for a weakness which makes it difficult to make interpersonal relations or friendship among learners in computer mediated communication or web based learning.

• Journal of the Korean Society for Nondestructive Testing
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• v.16 no.3
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• pp.162-173
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• 1996

Dry magnetic particle inspection(MPI) was performed to detect the surface defects of steel ingot cast billets. Magnetic properties of several materials were characterized by the measurement of the B-H hysteresis curve. The inspection results were evaluated in terms of the magnetizing current, temperature, and the amount of magnetic particles applied to billets. Magnetic flux leakage near the defect site of interest was measured and compared with the results of calculation by the finite element method in the case of direct magnetizing current. Direct and alternating magnetizing currents for materials were deduced by the comparison of the inspections. Results of the magnetic particle inspection by direct magnetizing current were compared with those of finite element method calculations, which were verified by measuring magnetic leakage flux above the surface and the surface defects of the material. For square rods, due to the geometrical effect, the magnetic flux density at the edges along the length of the rods was about 30% of that at the center of rod face for a sufficiently large direct magnetizing current, while it was about 70% for an alternating magnetizing current. Thus, an alternating magnetizing current generates rather uniform magnetic flux density over the rods, except for the region on the face across about 10 mm from the edge. The attraction of the magnetic particle by the magnetic leakage field was nearly independent of the surface temperature of the billets up to $150^{\circ}C$. However, the temperature should have been limited below $60^{\circ}C$ for an effective fixing of gathered magnetic particles to the billet surface using methylene chloride. We also found that the amount of applied magnetic particles tremendously affected the detection capability.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.24 no.5
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• pp.433-441
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• 2006

With a development of electrical technology in recent, it is possible to measure distance without direct contact to object using laser which launched at instrument and reflect from object. Furthermore, the advent of non prism total station brought the increment of application in many fields including not only road, airport, and harbors but also measurement and monitoring of structural displacement in construction fields. In this study, therefore, to evaluate accuracy of non prism total station, accuracy was analyzed by measuring certain distance which classified by both certain materials and angle of reflection. By this method, the derived values were applied to topographical survey for the efficient applicability. According to a study, result value of non prism total station was satisfBctory regardless of material when the angle of reflection was 90 degrees. RMSE increased when the angle of reflection are gradually increased to acute angle. In result of regression analysis using certain distance which classified by both materials and angles of reflection, there is relationship between distance and angle of reflection, but material has no relevance to the result value. When carrying out general topographical survey, proper application of non prism total station will go far conducting safe and prompt survey at the dangerous site such a road which have lots of traffic flow and rock joint which have high angles of inclination.

• International Journal of Highway Engineering
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• v.8 no.3 s.29
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• pp.77-88
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• 2006

The maintenance / repair of concrete pavements has become an issue as a result of increasing of concrete pavements' service year. Asphalt overlay is applied to the concrete pavements after partial repairs on all occasions. This thesis discusses the application standard, evenness, skid resistance, noise, economical efficiency, extension of life span, etc. of diamond grinding, a method of maintenance about concrete pavements. Based on this, it was applied to the field and measured the performance. It was measured the longitudinal evenness of before and after the construction through measurement equipment. and surveyed the skid resistance the each lane classified using the SN standard value. In case of noise, it is selected the kind of vehicle, velocity, then measured the noise between control and constructed site. In addition, it is evaluated the average texture depth. As a result of the analysis, longitudinal evenness is improved about $6{\sim}40%$, skid resistance is improved 66% at first section,37% at second section. Noise is reduced 3.4dB average, and average texture depth is 79% deeper than control section. Therefore, it can be concluded that diamond grinding is suitable as maintenance / repair method of concrete pavements.

• Journal of Cadastre & Land InformatiX
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• v.49 no.2
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• pp.123-134
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• 2019

The introduction of the world geodetic reference system in cadastral sector can apply the international standardization of cadastral survey and can be the basis for the creation of new industries by merging with other industries based on spatial information. With the introduction of the world geodetic reference system, non-coincidence land may cause problems which are whether the cadastral record and the real estate register are not consistent, etc. This problem infringes on the protection of ownership of citizens suggested in the main purpose of ｢Act On The Establishment, Management, Etc. Of Spatial Data｣. We have analyzed at overlapping cases between private land and overlapping cases between national and public land and suggested institutional improvement measures to solve problems arising on the site. As a result, it will be necessary to introduce a transformation verification measure by the world geodetic reference system in order to assign a function as a cadastral records to mapping converted to the world geodetic reference system. It is also expected that the legal and institutional basis should be established for alert adjustment and positioning through verification measures. Finally, it is difficult to determine the transformation factor as the co-ordinates of common points also differ because survey results vary by work area. Therefore, it is deemed necessary to consider the requirement to use the cadastral measurement basis by the world geodetic reference system in 2021.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.30 no.6_1
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• pp.539-547
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• 2012

Volume survey for earthwork is conducted periodically at every month at large scaled construction sites for request payment for the construction. Currently, the earthwork volume is calculated on the overlapped drawing for two cross sections which were created by new and previous surveying data observed by GPS and TS. However the survey is required lots of time and expenses as it is a pin-point surveying method thus surveyors intend to get data only for the heavy undulated topographic features chosen by himself to save time and expenses. Consequently, it causes poor results due to low dense measurement as well as it's not matched with the results by another surveyors. As a result, the conflicts related in earthwork volume calculation often arises among the owner, contractors and sub contractors. In this study, we developed a method to get surveying data for fast and accurate volume calculation using 3D Mobile Laser System and conducted an application test. Also we carried out experiments for topographic survey using MLS to judge for the application additionally. The results showed that we could reduce a time for cross section survey from 48 hours to 2 hours and collected high dense data which have 0.2m interval instead of 3m interval compare with existing method. Also we could make a map which has high accuracy within 10cm in horizontal through topographic survey using MLS.

• Journal of Conservation Science
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• v.29 no.4
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• pp.297-309
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• 2013

Iron objects become corroded at fast speed from the moment when they are excavated, so it is needed to control corrosion through processes of conservation treatment. However, re-corrosion mostly takes place in excavate iron objects, although they have already gone through the process of conservation treatment, and it is more difficult to carry out the second conservation treatment of re-corroded excavated iron objects than the first conservation treatment, and it requires a longer period of time to treat them as well. In this study, aims to discover factors of re-corrosion by scientifically analyzing corrosion products generated during the process of storage after the process of conservation treatment. The finished on conservation treatment of the iron artifacts, which were unearthed from three ancient site in Gyeongju by using the same conservation method between 2002 and 2009, re-corrosion condition observed on the packaging-iron artifacts. Focused on 9 target forged iron artifacts among them, this study analyzed the physical changes by mass measurement, naked-eye and microscopic observations and the chemical changes by SEM-EDS, XRD, IC and ICP analysis. The results show that the yellowish brown corrosion products formed on the facing surface of part dropped from the artifacts had different associated forms but acicular shape. In addition, the acicular shape became clearer as the color changed from red to yellowish brown. According to the process when the conservation treatment was completed, the mass of the artifacts increased in proportion to the corrosion products and the chloride ion ($Cl^-$) concentration had a tendency to increase relatively. ${\beta}$-FeOOH (akaganeite) was confirmed in the XRD analysis for the corrosion products of all the collected samples. As a result of ICP analysis, $Na^+$ and $Ca^{2+}$ components were confirmed.

• Journal of the Society of Disaster Information
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• v.8 no.3
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• pp.310-318
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• 2012

Actual condition by items based on the level of execution of Construction Company certified by Construction Safety and Health Management Systems (KOSHA 18001) was investigated, analyzed and evaluated reflecting various opinions fincluding safety experts, top management, audit experts, and construction engineers. Currently, the maintenance is being managed through internal audit after the safety and health management system has been certified, but it is difficult to identify the degree of continuous improvement. In order to present the standards to see the level of quantified system, this study was conducted. The purpose of this study is to present the system maturity evaluation tool to be used to reduce occupational accidents through proper establishment and continuous improvement of national health and safety management system. Results of this study are summarized through identification of current condition of implementation of KOSHA 18001 system, development of maturity measurement tool and verification as follows: First, priority of implementation for activities of headquarters and on-site was determined by importance of activities such as the risk assessment, safety and health accident prevention activities, performance assessment and monitoring, resource management and support, and management review and improvement in order. In addition, the expert group presented that association with continuous improvement activities could establish the system by presenting strengths, weaknesses and improvement subjects of system.