• Korean Journal of Fisheries and Aquatic Sciences
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• v.29 no.6
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• pp.893-899
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• 1996

The studies on the detoxification of paralytic shellfish poison (PSP)-infested blue mussels, Mytilus edulis and oyster, Crassostrea gigas were performed for using of available processing resource. Toxic blue mussel and oysters from Nampo in Masan Bay, Hachong in Koje Bay and Woepori in Koje were used for experimental samples. The toxicity of low toxic blue mussel $(A,\;84{\mu}g/100g;\;B,\;166{\mu}g/100g;\;C,\;295{\mu}g/l00g;\;D,\;557{\mu}g/100g)$ and oyster $(740{\mu}g/100g)$ were reduced below the regulation limit of PSP $(80{\mu}g/100g)$ or undetected level by mouse bioassay after boiling at $98^{\circ}C$ for 10 min and retorting at $115^{\circ}C$ for 70 min, while the toxicity of high toxic blue mussel $(E,\;8,760{\mu}g/100g)$ remained beyond the regulation limit after boiling and retorting at same condition. These results suggested that the regulation limit of PSP could be level up from $(80{\mu}g/100g)$ to about $160{\mu}g/100g$.

• Journal of the Korea institute for structural maintenance and inspection
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• v.19 no.5
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• pp.75-82
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• 2015

An experimental study has been carried out to examine development length effects for high strength headed deformed bars. Current design codes limit the specified yield strength of headed bars to 400 MPa. Such the limit is due to the lack of experimental studies on headed bars made of high strength materials. Thus a test program was planed with headed bars with the yield strength of 600 MPa. The threaded head type with head shapes of round plate and circular cone was selected in this study. The experimental variables were development length, number of bars, and head shape. Specimens were classified into L-type and S-type depending on the development length. The development length of L-type was computed according to the design code without considering the limit. S-type specimens had shorter development lengths than the L-type. Further classification was made depending on the shape of heads. A-types have the head shape of round plate and B-types have the shape of circular cone. Three L-type specimens were fabricated with the variable of number of bars (1, 2, and 3). Four specimens for each of SA and SB types were made with development lengths of 50%, 45%, 40%, and 35% compared with L-type. Pullout tests was carried out with 11 specimens. The test results were compared with computed strengths with the design code equations (Appendix II). Based the current studies, it can be said that high strength headed deformed bars used in this study be able to provide such strengths computed with the current design code without considering the yield strength limit.

• Transactions of the Korean Society of Automotive Engineers
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• v.22 no.3
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• pp.148-156
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• 2014

This study is a follow-up study of "Development of Plasma Ignition System" was presented at the 2013 KSAE spring conference. This study compares lean limit of conventional ignition system with plasma ignition system on constant volume combustion test & Engine Combustion test.

• Metals and materials international
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• v.24 no.6
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• pp.1412-1421
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• 2018

Cold-expanded austenitic high nitrogen steel (HNS) was subjected to investigate the effects of grain size on the stress-controlled high cycle fatigue (HCF) as well as the strain-controlled low cycle fatigue (LCF) properties. The austenitic HNSs with two different grain sizes (160 and $292{\mu}m$) were fabricated by the different hot forging strain. The fine-grained (FG) specimen exhibited longer LCF life and higher HCF limit than those of the coarse-grained (CG) specimen. Fatigue crack growth testing showed that crack propagation rate in the FG specimen was the same as that in the CG specimen, implying that crack propagation rate did not affect the discrepancy of LCF life and HCF limit between two cold-expanded HNSs. Therefore, it was estimated that superior LCF and HCF properties in the FG specimen resulted from the retardation of the fatigue crack initiation as compared with the CG specimen. Transmission electron microscopy showed that the effective grain size including twin boundaries are much finer in the FG specimen than that in the CG specimen, which can give favorable contributions to strengthening.

• Korean Journal of Pharmacognosy
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• v.48 no.1
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• pp.88-92
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• 2017

In the present study, we carried out quantitative analysis of chrysin and pinocembrin in Korean propolis by ultra performance liquid chromatography (UPLC) equipped with diode array detector. The separation was done using BEH C18 ($2.1{\times}50mm$, $1.7{\mu}m$) column with a mobile phase consisting of MeCN and 0.1% $H_3PO_4$ at 280 nm. The chromatographic method was validated for specificity, limit of detection, limit of quantification, linearity, precision, and accuracy. A quantitative analysis exhibited that the contents of the two compounds in Korean propolis collected from 8 inland areas except Jeju-do ranged from 3.1-46.0 mg/g. These results will be valuable as basic data for standardization of Korean propolis.

• Korean Journal of Pharmacognosy
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• v.47 no.2
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• pp.186-191
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• 2016

A new UPLC-DAD method for simultaneous determination of p-coumaric acid and trans-cinnamic acid in propolis was developed using Halo-C18 column and step gradient elution of MeCN and $0.1%H_3PO_4$ in 8 min. The method was validated by specificity, linearity, limit of detection, limit of quantification, precision(intra- and inter-day variability) and recovery tests. The validated method was sufficiently applicable for quantitative analysis of propolis products as well as propolis collected from different regions in Korea. The established method is simple, appropriate and efficient, and can be used for quality assessment of Korean propolis.

• Nuclear Engineering and Technology
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• v.52 no.8
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• pp.1847-1861
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• 2020

A design study was performed to improve the limit aseismic performance (LSP) of a primary heat transport system (PHTS) pump. This pump is part of the primary equipment of a prototype generation IV sodium-cooled fast reactor (PGSFR). The LSP is the maximum allowable seismic load that still ensures structural integrity. To calculate the LSP of the PHTS pump, a structural analysis model of the pump was developed and its dynamic characteristics were obtained by modal analysis. The floor response spectrum (FRS) initiated from a safety shutdown earthquake (SSE), 0.3 g, was applied to the support points of the PHTS pump, and then the seismic induced stresses were calculated. The structural integrity was evaluated according to the ASME code, and the LSP of the PHTS pump was calculated from the evaluation results. Based on the results of the modal analysis and LSP of the PHTS pump, design parameters affecting the LSP were selected. Then, ways to improve the LSP were proposed from sensitivity analysis of the selected design variables.

• Steel and Composite Structures
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• v.17 no.5
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• pp.573-599
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• 2014

A new type of connection for steel-concrete composite bridges was developed by the Steel Structures Laboratory of Ecole Poytechinque $F{\acute{e}}d{\acute{e}}rale$ de Lausanne. Resistance to longitudinal shear is based on the development of shear stresses in the confined interfaces which form the connection. Confinement is provided by the reinforced concrete slab which encloses the connection and restrains the uplift (lateral separation) of the interfaces by developing normal stresses. The experimental investigation of the interfaces, under static and cyclic loading, enabled the development of the laws describing the structural behaviour of each interface. Those laws were presented by the authors in previous papers. The current paper focuses on the continuity of the research. It presents the experimental investigation on the new connection by means of push-out tests on specimens submitted to static and cyclic shear loading. Investigation revealed that the damage in the connection, due to cyclic loading, is expressed by the accumulation of a residual slip. A safe fatigue failure criterion is proposed for the connection which enabled the verification of the connection for the fatigue limit state with respect to the limit of fatigue. A numerical model is developed which takes into account the laws describing the interface behaviour and the analytical expressions for the confinement effect, the latter obtained by performing finite element analysis. This numerical model predicts the shear resistance of the connection and enables to assess its fatigue limit which is necessary for the fatigue design proposed.

• Korean Journal of Child Studies
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• v.38 no.1
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• pp.117-126
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• 2017

Objective: The purpose of this study was to investigate young children's nonsymbolic magnitude comparison ability according to ratio limit and task condition. Methods: The participants included 40 3-year-old children, 42 4-year-old children, and 41 5-year-old children recruited from 4 childcare centers located in Seoul, Korea. All magnitude comparison tasks were composed of image material tasks and concrete material tasks. In addition, each magnitude comparison task varied with the ratio of the two quantities; 0.5 ratio, 0.67 ratio, 0.75 ratio. Results and Conclusion: The results revealed that 3-, 4-, and 5-year-old children could perform nonsymbolic magnitude comparison tasks without learning experiences. Also, 3-, 4-, and 5-year-old children could perform concrete material tasks better than image material tasks in nonsymbolic magnitude comparison tasks. Furthermore, children's performance on nonsymbolic magnitude comparison tasks indicated the ratio signature of the approximate number system. Children have a degree of numerical capacity prior to formal mathematics instruction. Also, children were influenced by task conditions or sense stimulus when they processed numerical information. Furthermore, the approximate number system can be used in understanding the ordinality of number.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2000.04a
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• pp.375-382
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• 2000

This paper briefly summarizes the basic concepts and main characteristics of seismic design of New Zealand Standards(NZS) with regard to reinforced concrete(RC) structures. NZS used the concept of the capacity design and the limit state design to satisfy the requirements of serviceability and safety. Plastic mechanisms and details with respect to the limit state of safety are briefly presented in this paper. The understanding of this advanced seismic design concept will enable us to implement the basic theory of capacity design and contribute to the development of Korean seismic code in new generation,