• Journal of the Korea institute for structural maintenance and inspection
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• v.22 no.1
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• pp.99-106
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• 2018

This study presents experimental investigation on the residual capacity of fire-damaged voided slabs according to loading conditions. In this study, two voided slab specimens were fabricated, and heated by ISO standard fire during 120 minutes with different loading conditions of presence of loading. These specimens were cooled down to room temperature, and the residual capacity of fire-damaged voided slabs was investigated. Based on test results, thermal distribution of voided slab through the depth of concrete sections is different by the loading conditions. The temperature of loaded specimen is rapidly elevated through the whole depth of concrete sections compared to the unloaded specimen. The residual strength of fire-damaged voided slab specimens are 60% and 66% of that of voided slab specimen without fire damage, and the residual stiffness of fire-damaged voided slab specimens decreases by 15%~23% of that of voided slab specimen without fire damage. In case of voided slab specimens subjected ISO standard fire, the loaded specimen shows the decrease of 10% in the residual strength and the decrease of 15% in the residual stiffness compared to the unloaded specimen. It seems to result from higher temperature of bottom reinforcements in the loaded specimen due to the cracks, and more extensive damage on concrete cover of reinforcements by spalling process according to load level.

• Proceedings of the Korea Concrete Institute Conference
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• 1994.10a
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• pp.127-132
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• 1994

This study attemps to investigate the influence of heat of hydration occured during hardening on the strength development of high strength concrete. The concrete design strengths of 500kg/$\textrm{cm}^2$ and 700kg/$\textrm{cm}^2$ were considered to simulated the square columns having $80\times80cm$ and $100\times100cm$, respectively. Both standard curing and field curing specimen were prepared at the specified ages, and the cores were drilled out from the structure. The thermal sensors were installed into the specimen to measure the heat of hydration process occurred during the hardening. This paper tries to uncover the relationship between the temperature history of the concrete and strength development. The correlation of core strength and specimen strength with curing condition is also discussed. Further research is desired to enlight the relationship between strength and heat of hydration of high strength concrete.

• Transactions of the Korean Society of Automotive Engineers
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• v.7 no.6
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• pp.135-143
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• 1999

This investigation evaluates effects of notch depth, fatigue precrack length and side groove in impact specimen for estimation of a valid K1d by instrumented Charpy impact test. Specimen material is 6005-T6. for notch depth 2.0mm and 2.5mm specimens or within about 2mm fatigue precrack length with notch depth 2.0mm and 2.5mm specimens or within about 2mm fatigue precrack length with notch depth 2.0mm , dynamic fracture toughness [$K_{1d,(1)}$] obtained by crack initiation load($P_m$) should be used. Dynamic fracture toughness of side grooved specimens are overestimated to that of standard impact specimen about 15 %-20%. It is confirmed that the formula of dynamic fracture toughness obtained by impact absorbed energy is inappropriate for ductile materials.

• Fisheries and Aquatic Sciences
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• v.6 no.2
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• pp.97-100
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• 2003

The Japanese codling fish, Physiculus japonica (family Moridae) is recorded as new to the Korean fish fauna. The specimen was fished from the South-Eastern waters off Jeju Island, Korea in March 1999. Standard length of the specimen was 343.2 mm, with a thin barbel on ower jaw, 67 soft second dorsal rays, 71 soft anal rays and 12 lateral-line above scales. Identification key of this specimen as P. japonica in the family Moridae was teethless vomer, chin barbel and well-developed black ventral light organ located on the anterior of anus. We give a new Korean name Dol-dae-gu for P. japonica.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2006.05a
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• pp.230-233
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• 2006

In this study, the effects of residual stress induced by plastic injection molding process on the tensile behavior of plastic tensile test specimen were investigated. To manufacture plastic tensile test specimens, an injection mold based on the international standard system was designed and made. Cavity pressure and temperature sensors were installed inside of the presented mold to monitor pressure and temperature values during the cycle of injection molding. Injection molding simulation was performed with the same condition of experiment and linear structural tensile analysis was also performed with the initial condition of the residual stress. It was shown that the residual stress induced by injection molding has an effect on the experiment of tensile test and linear structural tensile simulation.

• Journal of Ocean Engineering and Technology
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• v.10 no.2
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• pp.98-105
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• 1996

A method is proposed to evaluate the elastic-plastic fracture resistance curve only with load displacement records without the crack length measurement in CT specimen. This method is based on the idea that the effect of plastic deformation and the crack growth can be measured only by using a load-displacement record. If we know the reference-load curve representing the hardening of specimen, then the crack extension can be calculated by the elastic compliance determined from the load ratio. The results of this proposed method were compared to those of the elastic-plastic fracture resistance curve for the ASTM standard unloading compliance method. The experimental results for two kinds of ductile materials showed that the proposed method well simulates the material J-R curves. This method is currently applied for CT specimens. but it can be extended to the other specimen geometries.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.2
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• pp.369-372
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• 2009

When measuring the luminous flux of a light source at the integrating sphere photometer, it can know the luminous flux to compare the standard lamp with the specimen lamp at the same location. But in case of PLS(plasma lighting system, microwave discharged lamp), that two lamps are cannot be the same location. If the reference illuminant and specimen lamp are cannot measure identical location, we should measure the variation of the luminous flux. For the outcome we can turn out a correction factor to revise and reflect it. But the better way is calibrate the specimen lamp locate the identical location of reference illuminant measured. In this thesis, we've test to find the correction factor for consider that change the measuring location. And it turns out the correction factor. From this, it presents the result to make a select for the reference illuminant which is against the illuminant type for newly produce.

• Fisheries and Aquatic Sciences
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• v.24 no.5
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• pp.191-196
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• 2021

A single specimen of Liparis punctulatus (30.9 mm standard length) belonging to the family Liparidae, was collected in the waters off Busan on 4 August, 2016. This species is characterized by a single pair of nostrils, unlike other Liparis species. It is distinguished from L. ochotensis by the numbers of dorsal, anal, pectoral fin rays and the location of the gill opening (above the pectoral fin in L. punctulatus vs. extending ventrally in front of the pectoral fin). In the molecular analysis, 514 bp of 16S rRNA gene of the specimen in this study were identical to that of L. punctulatus from NCBI GenBank (K2P distance < 0.002). This is the first record of the species in Korea based on a voucher specimen, and we follow the Korean name "Kko-ma-kkom-chi" for this species proposed by Myoung et al. and Kim et al.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2022.11a
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• pp.187-188
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• 2022

In this study, the compressive strength and carbonation properties of geopolymer paste according to the amount of alkali admixture added were evaluated for the development of geopolymer concrete that recycles industrial waste. A geopolymer paste specimen was prepared using Ca(OH)2 as an admixture, and the prepared specimen was standard cured for 28 days. After curing, the compressive strength of the specimen was measured. As the amount of alkali admixture increased, the compressive strength increased. After curing, carbonation was carried out for 7 days in a CO2 5% environment. As a result of comparative evaluation of the amount of CaCO3 produced according to carbonation, the amount of CaCO3 produced increased as the amount of Ca(OH)2 added increased. However, when the amount of admixture added exceeds 5%, the increase rate decreases, so the optimum addition rate is considered to be 5%.

• Journal of the Korea institute for structural maintenance and inspection
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• v.26 no.1
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• pp.73-80
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• 2022

In this study, details of NRC beam-column connections were developed in which beam and columns pre-assembled in factories using steel angles were bolted on site. The developed joint details are NRC-J type and NRC-JD type. NRC-J type is a method of tensile joining with TS bolts to the side and lower surfaces of the side plate of the NRC column and the end plate of the NRC beam. NRC-JD type has a rigid joint with high-strength bolts between the NRC beam and the side of the NRC column for shear, and with lap splices of reinforcing bar penetrating the joint and the beam main reinforcement for bending. For the seismic performance evaluation of the joint, three specimens were tested: an NRC-J specimen and NRC-JD specimen with NRC beam-column joint details, and an RC-J specimen with RC beam-column joint detail. As a result of the repeated lateral load test, the final failure mode of all specimens was the bending fracture of the beam at the beam-column interface. Compared to the RC-J specimen, the maximum strength of the specimen by the positive force was 10.1% and 29.6% higher in the NRC-J specimen and the NRC-JD specimen, respectively. Both NRC joint details were evaluated to secure ductility of 0.03 rad or more, the minimum total inter-story displacement angle required for the composite intermediate moment frame according to the KDS standard (KDS 41 31 00). At the slope by relative storey displacemet of 5.7%, the NRC-J specimen and the NRC-JD specimen had about 34.8% and 61.1% greater cumulative energy dissipation capacity than the RC specimen. The experimental strength of the NRC beam-column connection was evaluated to be 30% to 53% greater than the theoretical strength according to the KDS standard formula, and the standard formula evaluated the joint performance as a safety side.