• Journal of Korean Tunnelling and Underground Space Association
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• v.13 no.1
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• pp.9-18
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• 2011

The spalling phenomenon occurs in high-strength concrete when several factors such as sharp temperature increase, high water content, low water/cement ratio and local stress concentration in material combine in the concrete material. On the basis of the factors, the preventing methods from the spalling are known as reduction of temperature increase, preventing of concrete fragmentation and fast drying of internal moisture. In this study, the reduction of temperature increase was proposed as the most effective spalling-preventing method among the spalling-preventing methods. Engineered cementitious composite for fireproof and repair materials was developed in order to protect the new and existing RC structures form exterior deterioration factors such as fire, cloride ion, etc. This study was carried out to estimate the fire-resisting performance of high strength concrete slab or tunnel lining by repaired engineered cementitious composite (ECC) or fiber reinforcement cemetitious composite (FRCC) under fire temperature curve. and them we will descrike the result of HIDA tunnel in Japan.

• Journal of the Korea institute for structural maintenance and inspection
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• v.18 no.1
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• pp.68-74
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• 2014

Recently, concrete facility as advanced water treatment facilities is extending in the water treatment facilities according to raise awareness of pure drinking water and delicious water. For this reason, it is increased to the necessity need to make the standard and the development of waterproofing and anti-corrosion materials for concrete structures applied water treatment tank. So, related research has become active recently. However, as the limit of research focused on durability improvement of top coating material, it is insufficient to study on the adhesion strength between the concrete surface and primer. Therefore, there is to confirm the adhesion of between concrete surface and the three primers used as anti-corrosion waterproofing materials, and to investigate the properties of adhesion strength according to the condition such as dry condition, wet condition, and water pressure condition of the concrete surface in this study.

• Journal of KIISE
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• v.42 no.2
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• pp.183-189
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• 2015

Recently, computer systems have encountered difficulties in making further progress due to the technical limitations of DRAM based main memory technologies. This has motivated the development of next generation memory technologies that have high density and non-volatility. However, these new memory technologies also have their own intrinsic limitations, making it difficult for them to currently be used as main memory. In order to overcome these problems, we propose a hybrid main memory system, namely HyMN, which utilizes the merits of next generation memory technologies by combining two types of memory: Write-Affable RAM(WAM) and Read-Affable RAM(ReAM). In so doing, we analyze the appropriate WAM size for HyMN, at which we can avoid the performance degradation. Further, we show that the execution time performance of HyMN, which provides an additional benefit of durability against unexpected blackouts, is almost comparable to legacy DRAM systems under normal operations.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.137-140
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• 2008

Minimizing the girder number and appling the long span deck of plate girder bridge is the main factors in the practical and economic design of the Twin Steel Girder Bridge. Therefore, it is important to verify the ability of the long span concrete deck. In this paper, to improve the problem, the precast concrete full depth deck has been used instead of cast-in-place concrete deck. The precast concrete full depth deck having longitudinal and transverse prestress is efficient to design of the long span concrete slabs. This paper introduces the design concept of Twin Steel Bridge using the precast concrete full depth deck and applied design case.

• Proceedings of the Korea Water Resources Association Conference
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• 2012.05a
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• pp.469-469
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• 2012

제주 지역은 대부분 지하수를 이용하고 있으며, 제주 서부지역의 경우, 지하수의 과다한 취수로 인해 지하수 하강은 물론 해수침투현상도 나타나고 있다.(제주미디어 2009.10) 제주지역의 지하수 적정 개발량은 약 97%에 이르고 있어 국지적으로는 지하수 개발이 한계에 이른 것으로 평가된다. 따라서, 농촌용수 공급을 위한 사업이 필요하며, 농업 환경 피해를 최소화할 수 있는 방안이 필요하다. 또한 농촌지역의 도시화에 따라 하수처리장의 농촌지역에도 늘어가고 있으며 이제는 농촌지역과 도시지역이 구분되지 않고 혼합되어 있는 형태로 발전하고 있기 때문에 과거의 농업활동도 변화되고 있으며, 하천에서 취수하는 용수중에서 농업용수로의 사용이 부적합한 용수가 취수되고 있다. 따라서 하수처리수의 농업용수 재이용시스템과 같이 수처리를 이용한 농업용수의 공급방안이 확대될 것으로 판단된다. 한국농어촌공사 농어촌연구원에서는 (주)필로스, (주)블루인바이로먼트엔텍과 함께 글로벌탑 환경기술개발사업의 과제를 수행하고 있으며, 본 연구를 통하여, 고내구성 고기능성의 복합막 기능이 부여된 UF/NF 분리막 소재 및 모듈을 개발하고 전기분해/오존조합에 의한 에너지 절약형 재이용수 공정기술을 개발하여, 판포하수처리장을 Test-bed로 선정하여 개발 기술을 적용하고자 한다. 제주도 한경면 판포리에 위치한 판포하수처리장은 하수재이용 사업을 통해 수처리 및 용수 공급 관로가 설치되어 있으며, 개발한 재이용수를 현지에서 공급 활용할 수 있어, 연구개발에 국한되지 않고 실증 플랜트에서 용수 사용자까지 연결이 가능하여 최적의 입지 연건을 가지고 있다. 개발될 시스템은, 유입조, ECR 반응조, AOPs, 나노버블을 이용한 막세정 시스템, UF/NF 시스템으로 공정이 설계되며, 제염처리는 물론 제주지역의 농업용수로써 안정적인 용수를 확보할 수 있는 시스템을 구축하고 있다. 본 연구개발을 통한 최종 목표는 하수처리장의 방류수 고도처리를 통해 도시, 농촌지역에 필요한 고품질 맞춤형 재이용수로 공급하고, 국내 외 하수 재이용시장으로 진출하는데 있다.

• Applied Chemistry for Engineering
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• v.32 no.4
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• pp.456-460
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• 2021

A potentiometric sodium-ion (Na⁺) sensor was prepared using a screen-printing process with carbon and silver inks. The two-electrode configuration of the sensor resulted in potential differences in Na⁺ solutions according to Nernstian equation. The obtained Na⁺-sensor exhibited an ideal Nernstian sensitivity, fast response time, and low limit of detection. The Nernstian response was stable when the sensor was tested for repeatability and long-term durability. The Na⁺-selective membrane coated onto the carbon electrode selectively passed sodium ions against interfering ions, indicating an excellent selectivity. The portable Na⁺-sensor was finally fabricated using a printed circuit system, demonstrating the successful measurements of Na⁺ concentrations in various real samples.

• Journal of the Microelectronics and Packaging Society
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• v.30 no.1
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• pp.1-16
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• 2023

Recently, the shift to next-generation wide-bandgap (WBG) power semiconductor for electric vehicle is accelerated due to the need to improve power conversion efficiency and to overcome the limitation of conventional Si power semiconductor. With the adoption of WBG semiconductor, it is also required that the packaging materials for power modules have high temperature durability. As an alternative to conventional high-temperature Pb-based solder, Ag sintering die attach, which is one of the power module packaging process, is receiving attention. In this study, we will introduce the recent research trends on the Ag sintering die attach process. The effects of sintering parameters on the bonding properties and methodology on the exact physical properties of Ag sintered layer by the realization 3D image are discussed. In addition, trends in thermal shock and power cycle reliability test results for power module are discussed.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.27 no.4
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• pp.246-257
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• 2015

The progressive degradation paths of structures have quantitatively been tracked by using stochastic processes, such as Wiener process, gamma process and compound Poisson process, in order to consider both the sampling uncertainty due to the usual lack of damage data and the temporal uncertainty associated with the deterioration evolution. Several important features of stochastic processes which should carefully be considered in application of the stochastic processes to practical problems have been figured out through assessing cumulative damage and lifetime distribution as a function of time. Especially, the Wiener process and the gamma process have straightforwardly been applied to armors of rubble-mound breakwaters by the aid of a sample path method based on Melby's formula which can estimate cumulative damage levels of armors over time. The sample path method have been developed to calibrate the related-parameters required in the stochastic modelling of armors of rubble-mound breakwaters. From the analyses, it is found that cumulative damage levels of armors have surely been saturated with time. Also, the exponent of power law in time, that plays a significant role in predicting the cumulative damage levels over time, can easily be determined, which makes the stochastic models possible to track the cumulative damage levels of armors of rubble-mound breakwaters over time. Finally, failure probabilities with respect to various critical limits have been analyzed throughout its anticipated service life.

• Journal of the Korean Institute of Gas
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• v.20 no.6
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• pp.23-30
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• 2016

The conventional natural gas engine realized lean combustion for the improved efficiency. However, in order to cope with exhaust gas regulations enforced gradually, the interest has shifted at the stoichiometric mixture combustion system. The stoichiometric mixture combustion method has the advantage of a three-way catalyst utilization whose purification efficiency is high, but the problem of thermal durability and the fuel economy remains as a challenge. Hydrogen-natural gas blend fuel (HCNG) can increase the rate of exhaust gas recirculation (EGR) because the hydrogen increases burning speed and lean flammability limit. The increase in the EGR rate can have a positive impact on heat resistance of the engine due to the decreased combustion temperature, and further can increase the compression ratio for efficient combustion. In this study, to minimize the exhaust emission developed HCNG engine with stoichiometric combustion method, developed three-way catalyst was applied to evaluate the conversion characteristics. The tests were carried out during the steady state and transient operating conditions, and the results were compared for both the conventional and proto-three-way catalyst of HCNG engine for city buses.

• Journal of the Korea institute for structural maintenance and inspection
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• v.25 no.5
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• pp.173-181
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• 2021

Reinforced concrete structures are exposed to various environments, resulting in reinforcement corrosion due to moisture and ions penetration. Reinforced concrete corrosion causes a decrease in the durability performance of reinforced concrete structures. One solution to mitigate such issues is using FRP rebars, which offer several advantages such as high tensile strength, corrosion resistance, and light-weight than conventional rebars, in reinforced concrete instead of conventional steel rebars. The FRP rebar used should be examined at the limit state because FRP reinforced concrete has linear behavior until its fracture and can generate excessive deflection due to the low elastic modulus. It should be considered while designing FRP reinforced concrete for flexure. In the ultimate limit state, the flexural strength of FRP reinforced concrete as per ACI 440.1R is significantly lower than the flexural strength by applying both the environmental reduction and strength reduction factors accounting for the material uncertainty of FRP rebar. Therefore, in this study, the experimental results were compared with the deflection of the proposed effective moment of inertia referring to the local and international standards. The experimental results of GFRP and BFRP reinforced concrete were compared with the flexural strength as determined by ACI 440.1R and Fib bulletin 40. The flexural strength obtained by the experimental results was more similar to that obtained by Fib bulletin 40 than ACI 440.1R. The flexural strength of ACI 440.1R was conservatively evaluated in the tension-controlled section.