국내 도로표지는 국토교통부에서 제정한 「도로표지 제작·설치 및 관리지침」을 토대로 설계와 시공이 이루어지고 있으며 문형식 과 편지식 도로표지 기초는 주로 역 T형 형식을 적용하고 있다. 기초 상단이 갓길 측은 성토 비탈면에, 중앙분리대 측은 포장 면에 위 치하여 기초 연결부가 고부식성 환경조건에 놓이게 된다. 이는 지주 및 앵커볼트에 부식이 쉽게 발생하고 장기적으로는 구조성능 저 하로 이어질 수 있는 사안이다. 아울러, 중앙분리대 측 문형식 도로표지 지주에는 방호 시설이 없는 상태로 차량 충돌 시 변형 또는 전도 위험과 2차 사고 발생 가능성 있다. 본 연구에서는 문형식과 편지식 도로표지 기초를 방호울타리 상단까지 높이는 방법으로 개선하였다. 풍하중에 의한 지주 휨모멘트 가 평균 18% 감소 되어 경제적인 설계가 가능하고 기초 연결부 환경조건이 개선되었다. 중앙분리대 측은 교통차단 등 특별한 조치 없 이도 상시 육안 점검이 가능하게 되어 유지관리 효율성이 증가하였고 방호성능 확보로 차량 충돌 시 지주 변형 또는 전도 위험이 해 소되었다. 결론적으로 기초 상단을 높임으로써 내구성, 유지관리 효율성 및 방호성능 향상을 기하면서도 경제적인 설계가 가능하게 되었다.

Interim dry cask storage systems comprising AISI 304 or 316 stainless steel canisters have become critical for the storage of spent nuclear fuel from light water reactors in the Republic of Korea. However, the combination of microstructural sensitization, residual tensile stress, and corrosive environments can induce chloride-induced stress corrosion cracking (CISCC) for stainless steel canisters. Suppressing one or more of these three variables can effectively mitigate CISCC initiation or propagation. Surface-modification technologies, such as surface peening and burnishing, focus on relieving residual tensile stress by introducing compressive stress to near-surface regions of materials. Overlay coating methods such as cold spray can serve as a barrier between the environment and the canister, while also inducing compressive stress similar to surface peening. This approach can both mitigate CISCC initiation and facilitate CISCC repair. Surface-painting methods can also be used to isolate materials from external corrosive environments. However, environmental variables, such as relative humidity, composition of surface deposits, and pH can affect the CISCC behavior. Therefore, in addition to research on surface modification and coating technologies, site-specific environmental investigations of various nuclear power plants are required.

This study aims to propose a simplified equation for estimating the bond strength of corroded reinforcing bars. To this end, extensive parametric analyses were performed using the detailed analysis method presented in the authors’ previous study, where a wide range of critical variables were considered, such as compressive strength of concrete, net cover thickness, and reinforcing bar diameter. The sensitivity in bond strength of the corroded reinforcing bar according to each variable was evaluated. On this basis, a simplified formula for the bond strength of the corroded reinforcing bar was derived through regression analysis. The proposed equation was rigorously tested and verified using the bond test results of corroded reinforcing bars collected from the literature. The results confirmed that the proposed equation could estimate the bond strengths of specimens with better accuracy than the existing models, providing a reliable tool for engineers and researchers. In addition, the proposed equation was used to analyze the development length required for corroded tensile reinforcement to exert its yield strength, and it showed that the cover thickness of concrete must be at least four times the diameter of the reinforcing bar to achieve the yielding strength of reinforcing bar even at a corrosion degree of more than 5.0%.

The growing significance of sustainable energy technologies underscores the need for safe and efficient management of spent nuclear fuels (SNFs), particularly via deep geological disposal (DGD). DGD involves the long-term isolation of SNFs from the biosphere to ensure public safety and environmental protection, necessitating materials with high corrosion resistance for DGD canisters. This study investigated the feasibility of a Cu–Ni film, fabricated via additive manufacturing (AM), as a corrosion-resistant layer for DGD canister applications. A wire-fed AM technique was used to deposit a millimeter-scale Cu–Ni film onto a carbon steel (CS) substrate. Electrochemical analyses were conducted using aerated groundwater from the KAERI underground research tunnel (KURT) as an electrolyte with an NaCl additive to characterize the oxic corrosion behavior of the Cu–Ni film. The results demonstrated that the AM-fabricated Cu–Ni film exhibited enhanced corrosion resistance (manifested as lower corrosion current density and formation of a dense passive layer) in an NaCl-supplemented groundwater solution. Extensive investigations are necessary to elucidate microstructural performance, mechanical properties, and corrosion resistance in the presence of various corroding agents to simplify the implementation of this technology for DGD canisters.

국내 건축물에서는 노후한 철근콘크리트 구조물의 안전성이 중요한 문제로 대두되고 있다. 구조물 부분이나 전체의 무너짐으로 인해 경제적 손실을 초래할 수 있으며, 이는 주로 구성 재료의 내구성 결 함으로 인해 발생한다. 여러 노후화 인자 중 동결융해와 부식은 주요한 열화 요인으로 작용한다. 동결 지역의 구조물은 동결융해가 위험 요소로 작용할 수 있으며, 해양 구조물은 해수에 존재하는 염소이온 에 의해 부식될 수 있다. 이러한 문제를 해결하기 위해서는 복합 열화 작용과 철근콘크리트 부재의 성 능 저하 관계를 이해하는 것이 필요하다. 본 연구는 동결융해와 부식의 복합적 피해가 RC 보의 거동 에 미치는 영향을 실험적으로 조사하였다. 7개의 RC 보를 제작하여 각각 다른 수준의 열화 조건을 부여한 후 휨 시험을 실시하였다.

Fundamental aspects of creating passivation layers for corrosion resistance in nuclear engineering applications, specifically the ability to form complete layers versus porous ones, are being explored in this study. Utilizing a laser ablation technique, 1,064 nm fire at 10 Hz with 60 pulses per shot and 0.5 mm between impact points, aluminum samples are treated in an attempt to create a fully formed passivation layer that will be tested in a LiCl-KCl eutectic salt. By placing these samples into an electrochemical environment mimicking a pyroprocessing system, corrosion rates, resistances and material characteristics are tested for one week and then compared between treated and untreated samples. In initial testing, linear sweep voltammetry indicates corrosion current density for the untreated sample at −0.038 mA·cm−2 and treated samples at −0.024 mA·cm−2 and −0.016 mA·cm−2, respectively. This correlates to a control sample corrosion rate of −0.205 mm·yr−1 and treated rates of −0.130 mm·yr−1 and −0.086 mm·yr−1 for samples 1 and 2. In addition, electrochemical impedance spectroscopy circuits show application of a longer-lasting porous passivation layer on the treated metal, compared to the naturally forming layer. However, the current technique fails to create a uniform protection layer across the sample.

In this study, we investigated the suppression of the corrosion of cast iron in a copper–cast iron double-layered canister under local corrosion of the copper layer. The cold spray coating technique was used to insert metals with lower galvanic activity than that of copper, such as silver, nickel, and titanium, between the copper and cast iron layers. Electrochemically accelerated corrosion tests were performed on the galvanic specimens in KURT groundwater at a voltage of 1.0 V for a week. The results revealed that copper corrosion was evident in all galvanic specimens of Cu–Ag, Cu–Ni, and Cu–Ti. By contrast, the copper was barely corroded in the Cu–Fe specimens. Therefore, it was concluded that if an inactive galvanic metal is applied to the areas where local corrosion is concerned, such as welding parts, the disposal canister can overcome local or non-uniform corrosion of the copper canister for long periods.

The current study explores the possibility of graphene as a protective layer on the zinc substrate through an optimized electrophoretic deposition process. Graphene has been synthesized from H2SO4, HNO3, and HClO4 solutions by an electrochemical exfoliation route. This method is known for providing a scalable and economical approach to the synthesis of graphene. The exfoliated graphene nano-sheets were characterized by X-ray diffraction, Fourier-transform infrared spectroscopy, UV–visible, and field emission scanning electron microscope to evaluate its properties. The three different synthesized forms of graphene nano-sheets were electrophoretically deposited onto Zn substrates at two different potentials. Scratch testing was employed to check the adhesion quality of the coatings. The corrosion behaviour of Zn and graphene-coated Zn substrates was studied in borate buffer and 3.5 wt% NaCl solutions through potentiodynamic polarization and electrochemical impedance spectroscopy. It

This study systematically investigated the efficacy of incorporating graphene/cerium hydroxide (GH) composite material into epoxy-modified polyurethane resin coatings for enhancing the corrosion resistance of Q690qE steel within polluted marine atmospheric conditions. The research encompassed a range of electrochemical assessments and analyses. Notably, the E/GH-0.3% coating displayed a substantially positive open-circuit potential (OCP) and prominently reduced corrosion current density, leading to annual corrosion rates of 2.72 mm/a following 25 days of immersion. Electrochemical impedance spectroscopy (EIS) elucidated the superiority of the E/GH-0.3% coating, characterized by the highest impedance modulus |Z| at 0.1 Hz, indicative of robust corrosion protection. Remarkably, the self-healing performance of E/GH-0.3% and E/ GH-0.5% coatings was evidenced by the formation of a composite passivation layer at scratch sites, particularly pronounced after 40 days of immersion. These findings underscore the promising potential of the GH composite as an effective corrosion inhibitor, holding significant promise for the advancement of protective coatings in harsh coastal industrial environments.