• Education of Primary School Mathematics
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• v.17 no.2
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• pp.127-157
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• 2014

The purpose of the study is to enhance the figure analysis ability for pre-service elementary teacher by using GSP. To do this, we limited to teaching competence divide into ability various problem-solving, extract key elements, predict the difficulty of student and investigated the initial of them, the reality of GSP construction. As results, pre-service elementary teachers made errors, proposed teaching focused on the character using in the problem solving, and found that in one particular difficulties to find the students. The reality of GSP construction activity was possible to explore through the partially constructed a number of various properties, but we found to have difficulty in the connection between concepts. and integrated view of the problem analysis. After visual identification and exploration through the GSP construction, problem-solving ability became a little more variety and changed their direction in order to focus the student's anticipated difficulties. From these results, we could extract some pedagogical implications helping pre-service teachers to reinforce teaching competence by GSP construction.

• Journal of the Korean Society of Safety
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• v.35 no.4
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• pp.56-63
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• 2020

The government has established various policies focusing on accident prevention to reduce the accident rate in the construction industry, but the effect is still insignificant. These results allude that there are still many problems in terms of usability. Although construction safety accidents usually have characteristics that occur during construction, the laws and systems should include the pre-construction cycle (plan/order - design - construction business management- construction) to eliminate risk factors in advance. The purpose of this study is to analyze the performance evaluation of the construction safety system before construction rather than during construction. In the pre-construction phase (plan/ order-design-constuction business management), we intend to investigate and analyze measures to prevent safety accidents and identify a system that lacks the ability to implement. Specifically, we analyzed what to focus on as precautionary measures in the planning, ordering, designing, and supervising. To improve them, we made a questionnaire based on the role related to construction safety for each subject, and seek implications for lack of performance through interviews. Based on the results, some ways to improve the safety system were proposed.

• Korean Journal of Construction Engineering and Management
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• v.13 no.6
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• pp.33-44
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• 2012

This study is as to payment improvement method of additional incidental cost to be occurred upon extension of public construction time. According to the result of analysis about the cause of non-payment of additional incidental cost of construction time extension through site examples, it was found that difficulties exist in disputes & proofing over the scope of actual cost recognition, and in this regard the result of experts opinion indicated that a construction extension pre-agreement system can be executed which agrees the scope of recognition of additional incidental cost of construction time extension once the statistical standard is clear and accurate. Accordingly, in this study, by totalling multiple sites data, calculations were implemented in terms of type of construction projects, amount of constructions, period of constructions. According to the result of calculation, the element of type of construction project and construction period appears to have none direct effect to the occurrence of additional cost of construction time extension, but direct relationship was indicated related to the contract amount element. In view of above, in this study a standard additional incidental cost of construction time extension was proposed, and presented a system improvement plan to implement the construction extension pre-agreement system.

• Journal of the Korean Geotechnical Society
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• v.23 no.10
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• pp.163-174
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• 2007

A New pre-loading system, through which a large pre-load could be charged was developed and applied to the braced wall in order to stabilize the adjacent tunnel. A pre-load larger than the designated axial force of bracing was imposed to prevent the horizontal displacement of the braced wall during the ground excavation. For this purpose, real scale model tests (1/10) were conducted, without and with pre-load on braced wall. And numerical analyses were performed for both the cases without and with pre-load, which were half (50%) and full (100%) respectively, and larger scale of the design axial farce of bracing. FEM program called PLAXIS was used for numerical analysis. As a result, it was found that the stability of the existing tunnel adjacent to the braced wall could be greatly enhanced when the horizontal displacement of braced wall was reduced by applying a pre-load, which was larger than the designated axial force of bracing.

• International Journal of Highway Engineering
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• v.17 no.6
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• pp.27-32
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• 2015

PURPOSES : It is difficult to estimate tunnel stability because of lack of timely information during tunnel excavation. Tunnel deformability refers to the capacity of rock to strain under applied loads or unloads during tunnel excavation. This study was conducted to analyze a methods of pre-evaluation of stability during tunnel construction using the critical strain concept, which is applied to the results of tunnel settlement data and unconfined compression strength of intact rock or rock mass at the tunnel construction site. METHODS : Based on the critical strain concept, the pre-evaluation of stability of a tunnel was performed in the Daegu region, at a tunnel through andesite and granite rock. The critical strain concept is a method of predicting tunnel behavior from tunnel crown settlement data using the critical strain chart that is obtained from the relationship between strain and the unconfined compression strength of intact rock in a laboratory. RESULTS : In a pre-evaluation of stability of a tunnel, only actually measured crown settlement data is plotted on the lower position of the critical strain chart, to be compared with the total displacement of crown settlement, including precedent settlement and displacement data from before the settlement measurement. However, both cases show almost the same tunnel behavior. In an evaluation using rock mass instead of intact rock, the data for the rock mass strength is plotted on the lower portion of the critical strain chart, as a way to compare to the data for intact rock strength. CONCLUSIONS : From the results of the pre-evaluation of stability of the tunnel using the critical strain chart, we reaffirmed that it is possible to promptly evaluate the stability of a tunnel under construction. Moreover, this research shows that a safety evaluation using the actual instrumented crown settlement data with the unconfined compression strength of intact rock, rather than with the unconfined compression strength of a rock mass in the tunnel working face, is more conservative.

• Journal of the Korea Safety Management & Science
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• v.10 no.3
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• pp.29-33
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• 2008

According to statistics released by the Ministry of Labor for the past 6 years, work-related accidents in the construction industry have been on the continued increase, resulting in social and economic losses that are difficult to determine at an exact amount. However, the number will likely get much bigger if unreported cases are included, considering the fact that the aforementioned statistics are based soley on the applications filed with Korea Workers' Compensation and Welfare Service. The practice of businesses choosing not to report and dealing with industrial accidents in an unauthorized manner is defined as "concealment of industrial accident". The reason the employers tend to engage in the concealment practice even at their huge cost is a "pre-qualification" scheme for the applicants in the government procurement process. Under the pre-qualification scheme, the applicants with a high rate of industrial accidents receive a low grade and become less attractive candidates in the procurement process, thus losing an opportunity to win a contract. Such failure relates directly to the fate of business organizations, to survive or not. That is why they are making all-out efforts to obtain a high grade in the pre-qualification evaluation. With regard to the accident-concealment problem, the following can be mentioned as preventive measures: (1) To exclude a rate of industrial accidents from the pre-qualification scheme; (2) To strengthen the institution of imposing penalties on the occurrence of industrial accidents; (3) To introduce private insurance system to the current industrial accident compensation insurance; and (4) To give non-recognition treatment to industrial accidents that were not reported upon occurrence. In conclusion, the concealment problem can be resolved if the aforementioned measures are to be taken continuously along with corrective measures against institutional deficiencies.

• Journal of the Korean Society for Advanced Composite Structures
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• v.6 no.4
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• pp.24-29
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• 2015

Bridge construction cost estimates have generally been conducted by using historial unit-price(per meter or square meter). The traditional estimating method based on unit-price references can never completely reflect the specialty of cable supported bridge. In this paper, we have developed the system for supporting the approximate construction cost and the quantity estimation based on 3D model information in the pre-project planning phase of 3-span continuous suspension bridge with 2-pylons. First of all, we'd analyzed the design information (such as structural design report, blueprint and quantity) and the real cost data from the existing suspension bridges and derived the design variables of the bridges. We developed the BIM wizard that generates a suspension bridge model parametrically based on derived design variables. The principle material quantities of suspension bridge are calculated directly from 3-dimensional bridge model built by using the BIM wizard. We have established the system that the construction cost can be estimated more specific than the traditional estimating method.

• International Journal of Naval Architecture and Ocean Engineering
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• v.5 no.3
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• pp.431-453
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• 2013

The principal purpose of this paper is to present a novel two phases rational scenario applied in constructing an offshore monopod platform; in which the two phases are the all-ground horizontal construction phase and the post-construction phase. Concerning the all-ground construction phase, a brief investigation of its different stages, i.e., pre-fabrication, fabrication, pre-assembling, positioning, assembling, and surface finishing is introduced. The important practical aspects of such construction phase are investigated without going into the nitty-gritty of the details involved therein. Concerning the post-construction phase, a clear investigation of its sequential stages, i.e., lifting, moving and up-righting is introduced. A finite element model (FEM) of the monopod platform is created to perform the structural analysis necessary to decide the suspension points/devices and the handling scenario during the various stages of the post-construction phase on a rational wise. Such structural analysis is performed within the framework of the three dimensional quasi-static modeling and analysis aiming at simulating the realistic handling condition, and hence introducing a reliable physical interpretation of the numerical results. For the whole effort to be demonstrated efficiently, the results obtained are analyzed, the conclusions are presented, and few related recommendations are suggested.

• Korean Journal of Construction Engineering and Management
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• v.20 no.6
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• pp.11-22
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• 2019

Current construction project processes pose difficulties for construction management as inefficient communication between project participants seldom accurately reflects the needs of the owner. To solve this problem, lean construction-based Integrated Project Delivery (IPD), which facilitates cooperation and builds trust through the formation of horizontal relationships among participants, is becoming increasingly popular. However, although lean construction-based IPD improves productivity in the construction industry, few studies have focused specifically on developing effective methods that maximize the benefits gained from lean construction-based IPD. This study therefore analyzed success factors for lean construction-based IPD projects by analyzing prior studies to identify factors that support IPD success. Application methods were analyzed and an example of how they are actually used in the field was examined through an in-depth single case analysis. The findings of this research can be applied to support lean construction-based IPD projects in Korea, improving their efficiency and boosting owner satisfaction.

• Explosives and Blasting
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• v.20 no.3
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• pp.59-71
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• 2002

The points of this design case are the planning and excavation method of a new double-tracked railroad tunnel which is approx. 11∼22 meters apart from existing single-tracked railroad tunnel. For the optimum excavation method some needs are required in design stage, such as the reduction of noise and vibration, public resentment, damage of buildings and construction costs. Hence the estimation and application of allowable noise and vibration criterion is important. The ground coefficient (K, n) of this site is determined by field trial blasting. The excavation method is chosen to satisfy the allowable noise and vibration criterion. In addition, in order to ensure the stability of existing single-tracked railroad tunnel, the instrumentation of maintenance level is accompanied during the construction stage. As a result of this design condition, central diaphragm excavation with line drilling and pre-large hole boring blasting is applied to the area within 15 meters apart from existing tunnel. And above 15 meters apart, pre-large hole boring blasting is designed.