• Journal of the Korea Institute of Building Construction
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• v.4 no.2
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• pp.89-95
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• 2004

1) As result of specimen with shear reinforcing bar of reinforced concrete beam, ductile coefficient of specimen was high in specimen containing Cockle shells based on non-mixed specimen. In increase rate of specimens, yield strength was similar in specimens containing Cockle shells and non-mixed specimens and maximum strength was higher in specimen containing Cockle shells. 2) To sum up the above experimental results, it is found that using splitted Cockle shells as aggregate for concrete by 10%～ 15% showed the same or higher compressive strength and shear strength as concretes using general aggregate and it can be used as substitute aggregate of concrete. It is considered that for future use of splitted Cockle shells as substitute concrete aggregate, continuous researches of its durability, applicability and economy are needed.

• Proceedings of the KIEE Conference
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• 2007.10a
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• pp.489-490
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• 2007

This paper is intended to trace and management of a medical specimen and its report in a hospital. To avoid missing and decaying specimen and to establish of order in the circulation of specimen, at the moment sampling, RFID tags for each are on examiner. And then, specimen is monitored easily, quickly and, correctly. We developed implementation LIS system has better CQI (Continuos Quality Improvement) using RFID and XML, ADO.net, ASP.net, C# 2.0. RFID technology replaces to an existing the bar-code system. Also for more convenience, we used a PDA-RFID module. The LIS system consists of main sorrel, SQL 2005, event display and analysis web page developed using asp.net 2.0 and sharing specimen data information using XML technology.

• Structural Engineering and Mechanics
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• v.62 no.5
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• pp.651-661
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• 2017

This paper presents an experimental study of bond-slip behavior of reinforced lightweight aggregate concrete (LC) and normal weight concrete (NC) with embedded steel bar. Tests were conducted on tension-pull specimens that had cross-sectional dimension with a reinforcing bar embedded in the center section. The experimental variables include concrete strength (20, 40, and 60 MPa) and coarse aggregate type (normal-weight aggregate and reservoir sludge lightweight aggregate). The test results show that as concrete compressive strength increased, the magnitudes of the slip of the LC specimens were greater than those of the NC specimens. Moreover, the bond strength and stiffness approaches zero at the loaded end, or close to the central anchored point of the specimen. In addition, the proposed bond stress-slip equation can effectively estimate the behavior of bond stress and steel bar slipping.

• Journal of the Korean Society of Safety
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• v.21 no.1 s.73
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• pp.92-95
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• 2006

This study is to find out how column with hole is behaved, compared to the normal one without hole. There might be existing buildings to make holes in the reinforced concrete column. Columns are made with commercially used compressive strength $240kg/cm^{2}$, air amount 5.0%, using re-bar of diameter D13 and D10 having yielding stress $4,000kg/cm^{2}$. The specimen were cured with temperature of $21{\pm}3^{\circ}C$. All specimens of five variables and all holes are geometrically considered and configurated. D3, D5 mean diameter 3cm and 5cm respectively. H1, H2 are the number of holes. Compressive pressure was forced in accordance with KS, following $0.6{\pm}0.4N/mm^{2}$ speed. Main re-bar's were strained with almost same shape through all the specimens. Hole diameter 5cm-having specimen showed cracking around hole. strains of back and front gauges of the specimen were showed similarly. Specimen having two holes in left and right from longitudinally axis resisted 7% less than the one having hole centrically from longitudinal axis. One hole having specimen with diameter 5cm resisted only 3% less than in case of 3cm diameter hole. Hole having in left and right from longitudinal axis will be less resistant than the case longitudinally arranged. Diameter 3cm hole showed less 10% capacity than normal one without hole. Capacity loss difference between diameter 3cm and 5cm showed almost none in case that they are arranged longitudinally.

• Korean Journal of Materials Research
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• v.28 no.7
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• pp.391-397
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• 2018

This study deals with the microstructure and tensile properties of 700 MPa-grade high-strength and seismic reinforced steel bars. The high-strength reinforced steel bars (600 D13, 600 D16 and 700 D13 specimens) are fabricated by a TempCore process, while the seismic reinforced steel bar (600S D16 specimen) is fabricated by air cooling after hot rolling. For specimens fabricated by the TempCore process, the 600 D13 and 600 D16 specimens have a microstructure of tempered martensite in the surface region and ferrite-pearlite in the center region, while the 700 D13 specimen has a microstructure of tempered martensite in the surface region and bainite in the center region. Therefore, their hardness is the highest in the surface region and shows a tendency to decrease from the surface region to the center region because tempered martensite has a higher hardness than ferrite-pearlite or bainite. However, the hardness of the 600S D16 specimen, which is composed of fully ferrite-pearlite, increases from the surface region to the center region because the pearlite volume fraction increases from the surface region to the center region. On the other hand, the tensile test results indicate that only the 700 D13 specimen with a higher carbon content exhibits continuous yielding behavior due to the formation of bainite in the center region. The 600S D16 specimen has the highest tensile-to-yield ratio because the presence of ferrite-pearlite and precipitates caused by vanadium addition largely enhances work hardening.

• Journal of the Korea institute for structural maintenance and inspection
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• v.19 no.3
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• pp.113-121
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• 2015

Building using masonry accounts for most of the smaller houses in Korea but due to brittle behavior and low ductility the frequency of usage has decreased in recent years. Despite this, this form of building has been gaining attention overseas for its low cost in construction and environment-friendliness of the materials. As such, many studies are being conducted to resolve the disadvantages in structure. This study produced an specimen for masonry-filled wall and the intersection to confirm the difference in structural movement depends on the existence or lack of expansion joint and verified the reinforcement effect from inserting a connecting steel item (steel plate, stainless steel twist bar). The experiment results show that the specimen with a steel plate inserted saw an increase in durability and an improvement in the strength of the specimens, while the specimen that had stainless steel twists bar inserted saw an increase in ductility that did not cause brittle failure, indicating that the reinforcement effects of inserting a connecting steel item are effective.

• Journal of the Korea Concrete Institute
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• v.23 no.6
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• pp.809-815
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• 2011

An experimental investigations on the bond-slip properties of the steel and Glass Fiber Reinforced Polymer(GFRP) bars in engineered cementitious composite (ECC) with Polyvinyl Alcohol (PVA) fibers are presented. Total of 8 beam specimens prepared according to the Rilem procedures with 2% of PVA and PE fiber volume percentage and steel and GFRP reinforcements significantly changed the failure mechanism and slightly improved bond strength. The main objective of the tests was to evaluate the load versus displacement and load versus slip behaviors and the bond strength for the following parameters: concrete type (normal and fiber concrete) and bar diameter (10 and 13 mm). The study results showed that ordinary concrete and ECC specimens showed similar behavior for steel reinforced specimen. However, GFRP reinforced specimen showed different behavior that the steel specimen. The code analytical results showed more accuracy compared to the experimental results as expected in conservative code provisions. Based on the obtained results, it is safe to conclude that the new parameters need to be adopted to ensure safe usage of ECC for construction applications.

• Proceedings of the Korea Concrete Institute Conference
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• 1994.10a
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• pp.350-355
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• 1994

This study is aimed at the experimental investigation of the influence of the structural parameters such as concrete cover, width of specimen and bar size on the dowel action of reinforcing bari in high strength concrete members. Based on the proper combination of these parameter, a total of 46 specimens has been cast for fc'= 500 ㎏/㎠ and another 46 specimens for fc'= 700 ㎏/㎠, and cured at the laboratory. Comparative analyses have been made for the parametric contribution to the dowel strength from the test results, and a regress equation has been suggested.

• Proceedings of the Korea Concrete Institute Conference
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• 1998.10b
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• pp.785-790
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• 1998

Ground Penetrating Radar (GPR) is a powerful tool with a wide range of applications in the nondestructive testing of concrete. It's useful for the detection of steel bars and delaminations embedded inside concrete, nondestructively. The purpose of this study is to detect a reinforced bar embedded inside concrete and to determine the range of application using GPR. A concrete specimen used for this study has a 25mm diameter steel bar and it's dimensions are 1,000 mm (L)× 1,000 mm(W)×280 mm(D). The advantages and limitations of GPR in these applications for concrete are also discussed.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2011.06a
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• pp.1173-1174
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• 2011