• Journal of Korean Society of Coastal and Ocean Engineers
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• v.32 no.4
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• pp.230-241
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• 2020

Since the construction of Pohang New Port, the problems of the low harbor tranquility caused by decreasing port operation rate has been continuously reported. In order to improve the harbor tranquility, a detached breakwater (DB) has been constructed outside the outer breakwater of Pohang New Port in 2018~2020. In this study, the effectiveness of the DB was proved by comparing the reduction rates of wave heights that were observed before and after the construction of the DB. First, the observed data were compared with the numerical model results available from a previous study, and the model data showed reasonable agreement with measured data at 3 out of 4 locations inside the port. The discrepancy in one of the locations was because the model could not accurately calculated the effect of wave interference in the inner corner of the port. The observation data showed excellent results that the number of waves that exceeded 0.3 m, the critical value to reach desired harbor tranquility, was significantly reduced after the construction of the DB. In addition, the reduction rate, the ratio of wave heights between outside and inside of the port, was decreased after the DB construction, which proved that properly designed coastal structures such as DB in this study could be effective in improving the port tranquility. The results of this study can be usefully applied for solving problems in similar cases.

• Journal of the Korean Recycled Construction Resources Institute
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• v.2 no.3
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• pp.180-187
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• 2014

The purpose of this study is to evaluate on the mechanical properties of High Volume Mineral Admixture(HVMA) high strength concrete to reduce the amount use of Ordinary Potland Cement, to discover the optimized HVMA binder and to test HVMA concrete based on the change of W/B and curing temperature. The results were shown as follows: The HVMA binder using the mixture of combined heat power plant fly ash and anhydrous gypsum known as inorganic activators with the mixture of blast furnace slag and fly ash was optimized. The mixture of HVMA high strength concrete at 26% of W/B ratio had a good result on flow characteristic and mechanical properties. High strength HVMA concrete over 50MPa is possibly manufactured over curing temperature $20^{\circ}C$.

• Journal of Technology Innovation
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• v.2 no.1
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• pp.170-190
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• 1994

The importantce of a development of competitiveness in domestic construction industry is growing as some of domestic construction markets is scheduled to open to foreign competing firms with higher level of construction technology and management. A national level of competitiveness in domestic construction industry and firms are partially, but significantly, affected by a technology level and a characteristics of production pattern. The purpose of the study is mainly to analyze and identify a technology level, production pattern and a development stage of R&D activities of domestic construction industry and firms. Based on these findings the study draws on a concluding remarks and derives technology policy implications. Results of analysis in the study impliy that (1) competitiveness of domestic construction firms(industry) in terms of technology level is relatively weak as compare to that of advanced foreign competing firms, (2) degrees of substitution of capital for labor are seemed to be relatively high, (3) R&D (investment) activities of domestic construction firms are generally spread out in forms of import, adjustment and betterment, and (4) only a small number of big domestic construction firms are seemed to afford to R&D investment for research facilities and equipments, but not enough for higher level of R&D man-power. The study suggests that technology policy for construction industry should be based on a fundamental policy directions. For example the increase in size and heightened quality level of R&D man-power should be placed in a top priority in policy agenda. Sound and specific policy items should be developed for planning and design, and maintenace and inspection technology in order to lead domestic industry to compete with foreign firms with full strength.

• Journal of the Korean Society of Systems Engineering
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• v.6 no.1
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• pp.61-68
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• 2010

Generally EPC management system was simply management concept through the normal S/W. Our LNG Plant R&D Center wanted to the excellent management system from the S/W. So We developed the R&D management S/W and EPC management S/W Built in the Microsoft Project Server. Our system made to the customer Requirements. It was just User Interface protocol. But User Interface has more Weak position, because it makes from the MS Project Servers. Ms Projector server make easy to treat the project on the WBS. EPC parts mixed WBS and normally Ms SQL Database. It has very complicated Structures. Now We planed to make the general Database and Ms Project Server, It' means to the S/W Developer and Schedule Manager ability. We will successfully integrate R&D management system and EPC system and other softwares.

• International conference on construction engineering and project management
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• 2015.10a
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• pp.540-543
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• 2015

Solar energy is one of the most important alternative energy sources which have been shown to meet high levels of heating and cooling demands in buildings. However, the efficiencies to satisfy these demands using solar energy significantly vary based on the characteristics of individual building. Therefore, this paper is focused on developing the methodology which can help to design optimal solar system for heating and cooling to be in cooperated within the existing buildings according to their load profiles. This research has established the Solar Heating and Cooling (SHC) system which is composed of collectors, absorption chiller, boiler and heat storage tank. Each component of SHC system is analyzed and made by means of Modelica Language and Pistache tool is verified the results. Sequential approximate optimization (SAO) and meta-models determined to 15 design parameters to optimize SHC system. Finally, total coefficient of performance (COP) of the entire SHC system is improved approximately 7.3% points compared to total COP of the base model of the SHC system.

• Korean Journal of Construction Engineering and Management
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• v.9 no.3
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• pp.85-94
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• 2008

The process of construction industry basically consists of many complicated phase, such as planning, design, construction, MO&R(Maintenance, Operation, and Repair), and deconstruction. And various participants communicate each other during every phase of process. Since construction components have become more complex and diverse recently, many researches on how to exchange and standardization of building. However, in Korea research on IFC(Industry Foundation Classes) which is a standard for international data exchange have been conducted with only study limited Issues, such as studies on the development of 2D extension model for IFC, researches on 3D or 4D based IFC extension, and etc. This stuff covers tests of the compatibility among commercial 3D CAD programs using IFC file format. Several problems of the current IFC model are retrieved as a result.

• Journal of the Korean Recycled Construction Resources Institute
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• v.11 no.1
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• pp.32-38
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• 2023

In this study, as part of the practical development of technology for CLSM using pond ash, the characteristics such as flowability, bleeding rate, and strength of the CLSM according to physical properties such as particle size distribution and particulate content of the pond ash were reviewed. As a result of analyzing the properties of the collected pond ash, it was found that the characteristics of density and particle size distribution were different. As a result of evaluating the characteristics of the CLSM for three types of pond ash, it was found that the blending conditions to satisfy the quality stipulated in ACI 229R were different, and mainly affected the particle size distribution characteristics and particulate content of the pond ash. In case of coarse-grained pond ash (PA-3), mixing conditions that satisfy the performance requirements stipulated in ACI 229R were not derived. But it is considered that further review is necessary according to particle size adjustment.

• 한국가스학회:학술대회논문집
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• 2003.10a
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• pp.65-72
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• 2003

현행 가스법상 지상식 LNG 저장탱크에 있어서 일정 용량의 저장탱크 주위에는 액상의 가스가 누출된 경우에 그 유출을 방지할 수 있는 방류둑(Dike) 또는 이와 동등 이상의 효과가 있는 시설을 설치하도록 규정하고 있어, 실제로 모든 지상식 LNG 저장탱크에 대해서 별도의 방류둑 설치를 의무화하고 있다. 또한, 예외규정으로 국제기준(international codes and standards)에 의해 설계되는 저장탱크는 심의를 통해 방류둑 기능을 인정할 수 있도록 하고 있다. 외국의 경우 LNG 저장탱크는 일반적으로 자국내 법령보다는 국제기준에 의해 건설됨으로써 1차 탱크로부터 일정거리의 둘레에 방류둑이 필요한 단일방호식 저장탱크 이외에 이중방호식, 완전방호식(full-containment) 및 멤브레인식(membrane) 저장탱크의 경우 외부(콘크리트, 강재)탱크가 방류둑 기능을 가지고 있어 별도의 방류둑이 필요없는 구조로 규정하고 있다. 멤브레인 LNG 저장탱크의 경우 프랑스, 일본 및 한국이 설계기술을 보유하고 있고, 최근 프랑스 및 한국에서 별도의 방류둑 없는 지상식 멤브레인 저장탱크 건설이 추진되고 있으나 양국 모두 자국법의 방류둑 규정에 의해 건설의 장애요소로 작용하고 있다. 따라서 지상식 멤브레인 LNG 저장탱크의 방류둑 기능에 대한 각 국의 법령 및 기준을 조사하고, 방류둑 일체형 저장탱크(완전방호식 및 멤브레인 저장탱크)의 형식별 안전성 평가 자료를 비교 검토함으로써 방류둑 일체형 멤브레인 저장탱크의 국내 도입의 타당성을 검토하고자 하였다. 조사결과 유럽, 미국 및 일본에서는 이중벽 LNG 저장탱크의 경우 콘크리트 외부탱크가 방류둑 기능을 가지는 것으로 규정하고 있으며, 특히 EN 1473과 제정중인 prEN 265002에서는 멤브레인 저장탱크의 경우 내부 멤브레인 탱크 누출시 단열시스템과 함께 외부 콘크리트 탱크가 액밀성 및 기밀성을 동시에 가지는 것으로 별도의 방류둑이 불필요함을 규정하고 있다. 프랑스 및 일본의 방류둑 일체형 LNG 저장탱크에 대한 위험성 평가 결과를 검토한 결과 멤브레인 저장탱크와 완정방호식 저장탱크는 안전성 차원에서 거의 동일한 것으로 나타났다. 따라서 국내에서 개발한 지상식 멤브레인 LNG 저장탱크 설계모델에 대한 안전성 제고 및 안전성 평가 등을 통해 객관적인 안전성 근거가 확보된다면 동 탱크의 경우에도 완전방호식 LNG 저장탱크와 같이 외부콘크리트 저장탱크의 방류둑 기능인정이 가능할 것으로 판단된다.

• Journal of Korean Tunnelling and Underground Space Association
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• v.24 no.6
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• pp.553-581
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• 2022

Shortly after tunnel boring machine (TBM) was introduced in the tunneling industry, the use of TBM has surprisingly increased worldwide due to its performance together with the benefit of being safely and environmentally friendly. One of the main cost items in the TBM tunneling in rock and soil is changing damaged or worn cutters. It is because that the cutter change is a time-consuming and costly activity that can significantly reduce the TBM utilization and advance rate and has a major effect on the total time and cost of TBM tunneling projects. Therefore, the importance of accurately evaluating the cutter life can never be overemphasized. However, the prediction of cutter wear in soil, rock including mixed face is very complex and not yet fully clarified, subsequently keeping engineers busy around the world. Various prediction models for cutter wear have been developed and introduced, but these models almost usually produce highly variable results due to inherent uncertainties in the models. In this study, a case study of design and construction of disc cutter change is introduced and analyzed, rather than proposing a prediction model of cutter wear. As the disc cutter is strongly affected by the geological condition, TBM machine characteristic and operation, authors believe it is very hard to suggest a generalized prediction model given the uncertainties and limitations therefore it would be more practical to analyze a real case and provide a detailed discussion of the difference between prediction and result for the cutter change. By doing so, up-to-date idea about planning and execution of cutter change in practice can be promoted.

• Journal of Korean Tunnelling and Underground Space Association
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• v.25 no.2
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• pp.65-85
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• 2023

The use of TBM (Tunnel boring machine) has increased worldwide due to its performance together with the benefit of being safely and environmentally friendly compared to conventional tunneling. In particular, EPB (Earth Pressure Balanced) TBM is widely used because it can be applied to various grounds compared to Open TBM. Also EPB TBM has a simple mechanical structure and advantages in cost, requires less ground area than Slurry TBM. EPB TBM has advantages in soft ground, and more importantly, can extend its applicability by use of appropriate soil conditioning, which improves mechanical and hydrological properties of excavated soil and increases the excavation performance of EPB TBM. Various studies suggested the proper mixing ratio and injection ratio, but almost they are limited to laboratory test under atmospheric pressure such as slump test. Actual field conditions may differ depending on the ground and mechanical condition. In this study, first the amount of used soil conditioning used in the field with various grounds from hard rock to soft ground was estimated through laboratory tests and compared with the estimate in design stage. And also it was compared with the amount used during actual excavation. In addition, experience of soil conditioning for the problems of cutter head clogging and groundwater inrush that occurred during excavation is discussed. Finally, lesson learned for the use of soil conditioning in difficult ground condition such as mixed ground are reviewed.