• Journal of the Korean Society of Industry Convergence
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• v.10 no.4
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• pp.207-211
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• 2007

The durable lifetime of RC structures is shortened by various reasons, which are the generation of cracks in construction and service term, the exterior deterioration according to climatic condition, the surface damage due to chloride attack and the corrosion of reinforced bars. The durability of concrete structures is nevertheless able to be increased by the method and the material of reinforcement and repair. The epoxy resin is widely used for reinforment and repair of concrete because of the superiority in mechanical property, adhesive property, abrasion resistance, impact resistance and chemical resistance. The epoxy cement mortar with hardening agent has a lot of disadvantages that are troublesome mixing work, weakened weatherability and high cost for hardening agent. In this study, the mix proportion of mortar is presented just only with epoxy resin and some admixtures, and the test result of mortar without hardening agent shows the higher strength than the mortar with hardening agent. In the mix proportion, the weight of epoxy resin must be less than 15% of the unit weight of cement, and 10% of unit weight of cement is adequate for the weight of admixtures.

• Korean Journal of Computational Design and Engineering
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• v.22 no.1
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• pp.10-17
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• 2017

The recent 3D printing industry has been focusing on developing 3D printers to fulfill the user's need to bring more colorful and realistic outcomes. Several 3D printers have deployed multiple extruders to print different colors. However, this method has a limit on its availability of colors. To solve this, recent research is focused on using mixing chambers to mix the possible colors to provide more color availability. In this paper, we discuss the environment and algorithm behind the development of G-code which allows a gradation effect of the mix of two filaments. The generation algorithm to make gradient G-code has been implemented in Cura using C ++ and Python.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2023.11a
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• pp.263-264
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• 2023

3D printing technology is recognized as a core technology that will lead the next generation, and is a field that can have a large ripple effect if it innovates the existing construction production method. Therefore, this study deals with the development of a 3d printing system using an articulated robot for construction purposes. In this system, ABB robot was used to control the developed cement gun accurately. The system is composed of mixer to mix cementitious materials, pump to transfer the materials, abb robot to motion control and cement gun to extrude the materials to print required construction parts. Using the system developed in this study, a suitable mix ratio of cementitious materials was found and successively printed a 1m high structure that demonstrated possibility of printing structures using 3d printer. In the future, we plan to build a foundation for automated construction through research on construction methods and materials that can be continuously layered for the system.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.12
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• pp.410-417
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• 2019

The enhancement effects of sea mustard extract (SME), starfish collagen peptide (SCP) and a mixture of the two (MIX) on skin activity were evaluated to investigate the possibility of using marine-derived extracts as cosmetic additives. The anti-inflammatory activity, whitening activity and skin elasticity activity of the extracts were analyzed to evaluate their skin-activating effects. Inhibiting the generation of nitric oxide (NO) and the tyrosinase and elastase inhibitory activities were assessed as the bio-markers for evaluating skin activity. SME, SCP and MIX did not show cytotoxicity within the concentration range of 1.0-50 ㎍/mL. In addition, SME, SCP and MIX all increased NO production and the tyrosinase and elastase inhibitory activities in a concentration-dependent manner. The activity of MIX was significantly increased compared to that with using SME or SCP alone. Taken together, when natural extracts are applied as cosmetic additives, the results demonstrate that using a mixture of SME and SCP may have a greater synergistic effect than that when using only a single extract. Therefore, this study contributes to the knowledge about the kinds and composition of several natural extracts when they are used as cosmetic additives.

• Environmental and Resource Economics Review
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• v.22 no.4
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• pp.691-726
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• 2013

We develop a hybrid model which allows the change in electricity generation mix by adding the electricity-sector components of bottom-up model to the conventional CGE model. The electricity sector is represented as a sum of separate generation technologies, each of which has the form of DRTS (Decreasing Returns to Scale) production function, unlike the conventional CGE model. We compare the effects of the 30% emission reduction target using the hybrid model with those using the conventional CGE model. The cost of meeting the target is lower with the hybrid model than the conventional CGE. It is consistent with previous studies in that adding the bottom-up components to the top-down model reduces the cost of emission reduction. In an extra analysis we find that an additional regulation like RPS (Renewable Portfolio Standard) increases the cost.

• International Journal of Concrete Structures and Materials
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• v.9 no.1
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• pp.69-88
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• 2015

Self-consolidating concrete (SCC) is a stable and cohesive high consistency concrete mix with enhanced filling ability properties that reduce the need for mechanical compaction. Limited standards and specifications have been reported in the literature on the structural behavior of reinforced self-compacting concrete elements. The significance of the research presented in this paper stems from the need to investigate the effect of enhanced fluidity of SCC on the structural behavior of high strength self-consolidating reinforced concrete beams. To meet the objectives of this research, twelve reinforced concrete beams were prepared with two different generations of superplasticizers and designed to exhibit flexure, shear, or bond splitting failure. The compared beams were identical except for the type of superplasticizer being used (second generation sulphonated-based superplasticizer or third generation polycarboxylate-based superplasticizer). The outcomes of the experimental work revealed comparable resistance of beam specimens made with self-compacting (SCC) and conventional vibrated concrete (VC). The dissimilarities in the experimental values between the SCC and the control VC beams were not major, leading to the conclusion that the high flowability of SCC has little effect on the flexural, shear and bond strengths of concrete members.

• Journal of Ubiquitous Convergence Technology
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• v.1 no.1
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• pp.23-27
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• 2007

Fruition for a diverse uIT(Ubiquitous Information Technology) service is currently required through the convergence of what is known as ubiquitous computing technology. In recent years, with the rapid growth of the need for information services, heavier demands have been made upon the supply of high-quality multimedia services that require a high bandwidth. Today, various home network solutions have been proposed to manage these service smoothly and a system able to deal with various types of network traffic without delays. In addition, in established home network environments that mix wired and wireless networks, along with the steady evolution of wireless network technology and the earnest development of ubiquitous computing technology, sensor-based wireless networks have emerged as a core solution for home networks. In this paper, a sensor network-based home control system supporting the next generation home gateway system for ubiquitous home environments is designed and implemented.

• Nuclear Engineering and Technology
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• v.54 no.10
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• pp.3695-3702
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• 2022

South Korea, a country that built a world-class nuclear power infrastructure, shifted to a nuclear phaseout during the previous government's reign. This shift was pursued as part of a larger task of electricity mix reform, and one of the integral motives for such reform is addressing greenhouse gas (GHG) and fine dust problems. Thus, verifying the relationships between the public's concerns about GHG/fine dust and their acceptance of nuclear power generation is essential for designing public communication strategies to revive nuclear power under the ongoing environmental regime. Our analysis using a nationwide survey sample of South Korea (N = 1009, through proportionated quota sampling method) showed that the more people are concerned about GHG and fine dust, the less they accept nuclear power. These relationships held even after controlling for the effect of a third variable-energy-related environmentalism. This finding means that despite past communication efforts positioning nuclear power as a generation source that can mitigate GHG/fine dust emissions and the widely accepted scientific evidence that supports such positioning, nuclear power in Korea is in jeopardy. Our finding provides implications for public communications and fundamental knowledge for research on the determinants of nuclear power acceptance.

• Structural Engineering and Mechanics
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• v.32 no.5
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• pp.685-699
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• 2009

Current research and development of high performance concrete, together with study of phenomena that are pertinent to impact resistance, have lead to a new generation of barriers with improved properties to resist impact loads. The paper reviews major properties and mechanisms that affect impact resistance of concrete barriers as per criteria that characterize the resistance. These criteria are the perforation limit, penetration depth and the amount of front and rear face damage. From the long-known, single strength parameter that used to represent the barriers' impact resistance, more of the concrete mix ingredients are now considered to be effective in determining it. It is shown that the size and hardness of the aggregates, use of steel fibers and micro-silica have different effects on performance under impact and on the resistance. Additional pertinent phenomena, such as the rate and size effects, confinement and local versus global response, are pointed out with their reference to possible future developments in the design of impact resisting concrete barriers.

• Proceedings of the KIEE Conference
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• 2008.11a
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• pp.426-428
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• 2008

현재 우리는 화석연료의 고갈 및 에너지 수입 해외의존도의 심화, 최근의 고유가 등으로 신재생에너지원의 개발 및 이용, 보급 확대가 국가적 관심사항이 되고 있으며, 신재생에너지를 전원을 보급하기 위해 노력하고 있다. 정부는 2012년부터 RPS(Renewable Portfolio Standard)를 도입하여 신재생에너지전원의 비중을 설비용량의 5%(발전량의 7%)까지 확대하는 것을 목표로 하고 있다. 따라서 본 연구에서는 가격규제가 아닌, 보급목표를 규제하여 시장에서 가격이 결정되는 RPS를 도입하였을 경우의 현 전력수급계획의 수립절차에 대한 상세한 고찰과 문제점 분석을 통해 우리나라의 RPS를 반영한 최적 전원구성비를 도출하기 위한 방안을 GATE-PRO(Generation And Transmission Expansion PROgram) 모형을 이용하여 모색하고자 한다. 또한 이를통해 우리나라의 RPS도입이 전력수급계획에 미치는 영향을 살펴보고자 한다.