• Journal of the Korean GEO-environmental Society
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• v.10 no.6
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• pp.79-88
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• 2009

In this study, it was studied on arching characteristics of a grand section tunnel with pre-steel-rib nail reinforcement. In this study, we examine the adaptation of tunnel plan and the case which is based on the strengthening method for preexistence tunnel and other pre-steel-rib nail while the upper part of cover depth is low or soil condition is bad. When the pre-steel-rib nail as new technology and method reinforces the foundation placed of grand section tunnel, it is much better in strengthening effect, safety and effectiveness than the conventional one. After investigation about the plan pre-steel-rib nail method, construction case and calibration data, it was confirmed and examined about the upper part of tunnel for strengthening the pre-steel-rib nail thereby arching characteristics of grand section tunnel using MIDAS/GTS finite element program. Moreover we present the method that could upgrade the accurate installation interval and adaptation method for strengthening effect to adapt the pre-steel-rib nail method in a foundation placed over a tunnel.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.48 no.1
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• pp.43-53
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• 2020

The effect of the relative location between pre-swirl nozzle and receiver hole on the performance of radial on-board injection type pre-swirl system was analyzed. In this study, tendency of the change of discharge coefficient and temperature drop efficiency were analyzed for 20 design points through the combination of 5 pre-swirl nozzle location and 4 receiver hole location. Discharge coefficient of system tended to be similar to the pressure ratio of the pre-swirl nozzle. System performance variation occurred as the flow structure in the cavity was affected by the surface, and the influence of the stationary surface is greater than that of the rotating surface. Discharge coefficient of system changed -1.39% to 1.25% and temperature drop efficiency changed -5.41% to 2.94% refer to reference design point.

• Steel and Composite Structures
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• v.30 no.2
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• pp.81-96
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• 2019

The behavior of a new Three-Tube Buckling-Restrained Brace (TTBRB) with circumference pre-stress (${\sigma}_{{\theta},pre}$) in core tube are investigated through a verified finite element model. The TTBRB is composed of one core tube and two restraining tubes. The core tube is in the middle to provide the axial stiffness, to carry the axial load and to dissipate the earthquake energy. The two restraining tubes are at inside and outside of the core tube, respectively, to restrain the global and local buckling of the core tube. Based on the yield criteria of fringe fiber, a design method for restraining tubes is proposed. The applicability of the proposed design equations are verified by TTBRBs with different radius-thickness ratios, with different gap widths between core tube and restraining tubs, and with different levels of ${\sigma}_{{\theta},pre}$. The outer and inner tubes will restrain the deformation of the core tube in radius direction, which causes circumference stress (${\sigma}_{\theta}$) in the core tube. Together with the ${\sigma}_{{\theta},pre}$ in the core tube that is applied through interference fit of the three tubes, the yield strength of the core tube in the axial direction is improved from 160 MPa to 235 MPa. Effects of gap width between the core tube and restraining tubes, and ${\sigma}_{{\theta},pre}$ on hysteretic behavior of TTBRBs are presented. Analysis results showed that the gap width and the ${\sigma}_{{\theta},pre}$ can significantly affect the hysteretic behavior of a TTBRB.

• Advances in concrete construction
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• v.10 no.1
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• pp.13-20
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• 2020

Steel corrosion in embedded steel causes a significant durability problems and this usually propagates to structural degradation. Large-scaled concrete structures, PSC (Pre-stressed Concrete) or RC (Reinforced Concrete) structures, are usually constructed with mass concrete and require quite a long construction period. When they are located near to sea shore, chloride ion penetrates into concrete through direct or indirect exposure to marine environment, and this leads durability problems. Even if the structures are sheltered from chloride ingress outside after construction, the chloride contents which have been penetrated into concrete during the long construction period are differently evaluated from the initially mixed chloride content. In the study, chloride profiles in cores extracted from anchorage concrete block in two large-scaled suspension bridge (K and P structure) are evaluated considering the exposure periods and conditions. Total 21 cores in tendon room and chamber room were obtained, and the acid-soluble chlorides and compressive strength were evaluated for the structures containing construction period around 3 years. The test results like diffusion coefficient and surface chloride content from the construction joint and cracked area were also discussed with the considerations for maintenance.

• Journal of the Korean housing association
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• v.23 no.4
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• pp.49-57
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• 2012

This study was conducted to apply the modular construction method to Han-ok. The modular method, which is differentiated from the existing one, means a construction method that equipments, windows and interior materials are prefabricated as a six-sided object at a plant and then they are assembled at the least process on the spot. As for the theoretical observation, the theoretical basis to apply the modular method to the modular housing and Hanok was divided into environmental and economic aspect. In order to apply the modular method to Hanok, the unit scale and size were selected and the plane of unit module Hanok was developed. And a standard with regard to the unit combination and material lifting transportation method was set and planned. In addition, through the comparison the unit modular Hanok to the existing Hanok, the difference was analyzed and the strength was identified in terms fo design method, structure, construction method, period and cost. In final, the conclusion, with regard to the economic, technical application in future, was drawn through arranging the study contents. The unit modular Hanok to carry out the high-quality dwelling through construction period reduction, standardized construction materials and improved insulation performance can meet the demands for a paradigm of new construction technology.

• Proceedings of the Korean Institute Of Construction Engineering and Management
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• 2007.11a
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• pp.13-18
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• 2007

The construction by the ministry of health and welfare support of the first special hospital for only children in busan and gyeong-nam is under building with YPNUH(Yangsan Pusan National University Hospital) for the best medical treatment town and is to improve the productivity and efficiency by eliminating unproductive and inefficient fact through the construction management, systemic and scientific management technique. So in this study we would like to suggest the generated effect to apply project management technique to all stage such as from pre-design phase, turn-key enterprise choice, construction, design VE(Value Engineering), PMIS (Project Management Information System) construction to maintenance phase and cost and schedule reduction effect through basic, execution design VE by using engineer of field.

• International Journal of Highway Engineering
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• v.16 no.1
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• pp.75-89
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• 2014

PURPOSES : This study evaluates the economic value of national highway construction projects using Real Option Pricing Models. METHODS : We identified the option premium for uncertainties associated with flexibilities according to the future's change in national highway construction projects. In order to evaluate value of future's underlying asset, we calculated the volatility of the unit price per year for benefit estimation such as VOTS, VOCS, VICS, VOPCS and VONCS that the "Transportation Facility Investment Evaluation Guidelines" presented. RESULTS : We evaluated the option premium of underlying asset through a case study of the actual national highway construction projects using ROPM. And in order to predict the changes in the option value of the future's underlying asset, we evaluated the changes of option premium for future's uncertainties by the defer of the start of construction work, the contract of project scale, and the abandon of project during pre-land compensation stages that were occurred frequently in the highway construction projects. Finally we analyzed the sensitivity of the underlying asset using volatility, risk free rate and expiration date of option. CONCLUSIONS : We concluded that a highway construction project has economic value even though static NPV had a negative(-) value because of the sum of the existing static NPV and the option premium for the future's uncertainties associated with flexibilities.

• Journal of Construction Engineering and Project Management
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• v.6 no.4
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• pp.7-14
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• 2016

While the idea of the existence of a set of key factors for success in planning, designing and construction of projects is not new, it remains one of the most important issues in the field of construction management. This is due to project success factors are inputs to project management practice which can lead directly or indirectly to project success. This study identifies the success factors which can be used for improving the highway projects performance in Egypt during the project pre-construction and construction phases. Through a detailed literature review 35 success factors are identified. Furthermore, the AHP is adopted to prioritize the studied factors through the application of questionnaire survey. The study establishes that implementing an effective quality control and assurance systems, allow sufficient time for feasibility studies, design, drawing and tender preparation, effective cost control system and frequency of project budget updates, preparing adequate designs and drawings and determining sufficient time to implement the desired scope of work are the most important success factors for enhancing the highway projects performance in Egypt.

• Proceedings of the KSR Conference
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• 2011.10a
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• pp.3312-3317
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• 2011

Recently, the demand regarding reliability and safety of the railroad are increased as built to Driverless LRT system. Therefore, PM and SE technique is applied for efficient management of a construction business. In case of SE(System Engineering) in domestic, most foreign companies are doing to lead but we are under effort for the environment that a domestic company can lead. In this study, We emphasize to SE importance of pre-business for operation to be effective of Driveless LRT system, and propose about activities in the SE at requirements definitions and requirements analysis steps of a highest level. To achieve this, We propose SE Application Methods of Pre-Business regarding assistance process of project planning, evaluation and control, and risk management.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.797-800
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• 2008

The pre-mixed concrete shotcrete, which can pre-bag the shotcrete materials and thus can save considerable labor activity, will be developed through extensive experiments. The proposed pre-mixed High performance Shooting concrete system included hydro-demolition will be verified though field tests in actual repair and rehabilitation construction sites. This research was on developing of the High performance Shooting concrete by evaluation of site application by field test using new automatic Hydro-demolition and Shotcrete equipment.