• 한국건축시공학회:학술대회논문집
• /
• 한국건축시공학회 2013년도 춘계 학술논문 발표대회
• /
• pp.27-28
• /
• 2013

This study investigates the effect of a protective layer on the level of carbonation resistance of concrete. For the protective layer, a PE film, bubble sheets, double layered bubble sheets and styroform were placed in a mold before placing the concrete. In addition, PE film was retrofitted by attaching on the surface of the substrate concrete with a glue. Results showed that the carbonation depths of the control concrete were 4.6 mm and 5.2 mm at one week and two weeks exposure in an accelerated carbonation chamber, whereas the concrete with all types of protective layer except PE flim did not allow the ingress of carbon dioxide during the same period.

• 한국콘크리트학회:학술대회논문집
• /
• 한국콘크리트학회 2001년도 봄 학술발표회 논문집
• /
• pp.739-744
• /
• 2001

In this study, experimental research was carried out to develop protective finishing, coating materials and new hybrid technique for deteriorating prevention and high durability in concrete structures. It had sufficiently recommended performance for the protective finishing method of concrete structures through testings. This is more progressive double membrane method than single membrane type designed by conventional method. It was found that this hybrid construction method had very excellent performance to improve the durability of existing concrete structures and attain the beauty of concrete structures.

• 한국군사과학기술학회지
• /
• 제12권5호
• /
• pp.571-576
• /
• 2009

In terms of protective engineering, there are no noticeable researches regarding covered-positions for smaller units in South Korea. So, standards to maintain and build protective facilities for larger units have been applied in ones for smaller units without any adjustment. The previous study was to calculate penetration depth of the concrete walls because the experiment performed indoor. In this outdoor experiment, velocity of projectile impact as one of the other important factors was considered to prove the validity of 30cm concrete wall thickness as effective protective level of the covered-position. Random effects and extraneous variables which could be occurred in outdoors experiment were controlled with statistical techniques. As a result, velocity of projectile impact was significant variable and the given standard, 30cm thickness of concrete walls was as valid as ever.

• 한국안전학회지
• /
• 제38권2호
• /
• pp.44-51
• /
• 2023

With the recent increase in gas energy use, risk management for explosion accidents has been emphasized. Protective walls can be used to reduce damage from explosions. The KOSHA GUIDE D-65-2018 suggests the minimum thickness and height of protective walls, minimum reinforcement diameter, and maximum spacing of reinforcements for the structural safety of the protective walls. However, no related evidence has been presented. In this study, the blast load carrying capacity of the protective wall was analyzed by the pressure-impulse diagrams while changing the yield strength of the reinforcement, concrete compressive strength, reinforcement ratio, protective wall height, and thickness, to check the adequacy of the KOSHA GUIDE. Results show that failure may occur even with design based on the criteria presented by KOSHA GUIDE. In order to achieve structural safety of protective walls, additional criteria for minimum reinforcement yield strength and maximum height of protective wall are suggested for inclusion in KOSHA GUIDE. Moreover, the existing value for minimum reinforcement ratio and the thickness of the protective wall should be increased.

• International Journal of Internet, Broadcasting and Communication
• /
• 제12권3호
• /
• pp.74-86
• /
• 2020

This study discussesresearch and development of large-sized 3D printers that can be applied to construction and civil engineering for various designs of protective casing on foam liner for concrete exteriors. The consistent use of concrete represents the current surroundings. However, concrete exteriors in Korea have not considered the regional characteristics, but the concrete has been poured solely for economical aspects for the last decade or two. There are many cases of poor installation and not enough design development projects to correct it. This study was conducted to apply various patterns, regional characteristics, and 3D printing for protective casing design for foam liner to create various designs for the concrete walls. Therefore, we started researching on a large 3D printer, and designed and developed this system. Considering the chronological process, the properties of concrete structures were identified, the application of designs for concrete in Korea and abroad and the 3D printing materials for the protective casing were surveyed and analyzed, and a stereotype was produced in the first year to study designs for the beauty of concrete surfaces. In the second year, images of regional characteristics were gathered, design ideas for regional promotion were derived, virtual images were produced along with design modeling to simulate the appearances, and verify the effect of application and promotion. Finally, in the third year, the 3D printer for concrete foam liner was constantly improved to analyze the 3D printing program and the various library elements to complete an actual large-sized 3D printer.

• Geomechanics and Engineering
• /
• 제28권3호
• /
• pp.209-224
• /
• 2022

In this study, the numerical analysis model of π-beam explosion is established to compare and analyze the failure modes of the π-beam under the action of explosive loads, thus verifying the accuracy of the numerical model. Then, based on the numerical analysis of different protection forms of π beams under explosive loads, the peak pressure of π beam under different protection conditions, the law of structural energy consumption, the damage pattern of the π beam after protection, and the protection efficiency of different protective layers was studied. The testing results indicate that the pressure peak of π beam is relatively small under the combined protection of steel plate and aluminum foam, and the peak value of pressure decays quickly along the beam longitudinal. Besides, as the longitudinal distance increases, the pressure peak attenuates most heavily on the roof's explosion-facing surface. Meanwhile, the combined protective layer has a strong energy consumption capacity, the energy consumed accounts for 90% of the three parts of the π beam (concrete, steel, and protective layer). The damaged area of π beam is relatively small under the combined protection of steel plate and aluminum foam. We also calculate the protection efficiency of π beams under different protection conditions using the maximum spalling area of concrete. The results show that the protective efficiency of the combined protective layer is 45%, demonstrating a relatively good protective ability.

• 한국콘크리트학회:학술대회논문집
• /
• 한국콘크리트학회 1997년도 봄 학술발표회 논문집
• /
• pp.203-209
• /
• 1997

An experimental study to evaluate to evaluate corrosion protection systems was undertaken with 44 reinforced concrete slab specimens subjected to cyclic wet and dry saltwater exposure. Corrosion measurements included monitoring macrocell corrosion currents, which are genrerally accecpted in United States practice. Test results indicate that specimens containing 2 kg/$\textrm{m}^3$ of NaCl and exposed to wet(outdoor) and dry(indoor) conditions but not to saltwater show very low values of corrosion measurements regardless applying any corrosion protective systems. Corrosion currents of the specimens exposed at 10 percent of NaCl were higher than that of the specimen exposed at 5 percent of NaCl, so the density of the salt water had an influential effect on the test. For the specimens with water repellent membrane currents kept relatively low numerical values, but test specimens with surface corrosion inhibitor protective system showed high values of corrosion current. It would be expected that evaluation of the corrosion protective systems need long-term measurement.

• 한국콘크리트학회:학술대회논문집
• /
• 한국콘크리트학회 2003년도 봄 학술발표회 논문집
• /
• pp.1061-1066
• /
• 2003

Chloride penetration into concrete is the main cause of the steel corrosion in concrete structures exposed to chloride-rich environments. Protective surface coatings are increasingly being applied to concrete structures to reduce chloride penetration. In this study, the performance of various surface coatings was evaluated. Most coatings showed good results for the various tests of the performance evaluation. Surface coatings can delay deterioration such as chloride-induced reinforcing bar corrosion effectively.

• 대한방사선기술학회지:방사선기술과학
• /
• 제33권4호
• /
• pp.363-367
• /
• 2010

본 연구의 목적은 X-선촬영장치의 1차방어벽두께 계산에 관한 쉬운 방법의 연구이다. X-선촬영장치에 대한 1차방어벽의 두께 계산을 위하여, 차폐물질은 콘크리트를 선택하였다. 방어벽의 구역들은 관리구역과 비관리구역으로 분류하였다. 두께의 계산은 NCRP 보고서 49와 51의 데이터를 사용하였다. 최대관전압 100과 150 kVp를 갖는 X-선촬영장치들에 대하여, 콘크리트 두께들은 거리의 함수로서 계산되었다. 계산된 데이터로부터, 식 (3), (4), (5), 그리고 (6)은 지수감소함수의 정합을 수행하여 얻었다. 본 연구에서 얻어진 수식들로부터, 1차방어벽의 두께는 근사적으로 계산할 수 있다.

• Structural Engineering and Mechanics
• /
• 제84권2호
• /
• pp.167-180
• /
• 2022

A strategic structure when exposed to direct hit of conventional bomb/projectile are severely damaged because of large amounts of energy released by the impact and penetration of bomb. When massive concrete slabs suffer a direct hit, the energy released during impact and penetration process are able to easily break up large mass of concrete. When over stressed under such impact of bombs, the concrete structure fails showing brittle behavioural nature. This paper is intended to study and suggest the protective measures for structures used for strategic application by adopting a means to dissipate the large quantum of energy released. To quantitatively evaluate the force, displacement and energy in such scenario, a fine numerical model of the proposed layered structure of different combinations was built in ANSYS programme in which tri-nitrotoluene (TNT) explosive was detonated at penetration depth calculated for GP1000 Lbs bomb. The distinct blast mitigation effect of the proposed structure was demonstrated by adopting various layers/barriers created as protective measures for the strategic structure. The calculated result shows that the blast effect on the structure is potentially reduced due to provision of buster slab with sand cushioning provided as protective measure to the main structure. This concept of layered protective measures may be adopted for safeguarding strategic structures such as Domes, Tunnels and Underground Structures.