• Proceedings of the Korean Society For Composite Materials Conference
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• 2000.11a
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• pp.79-83
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• 2000

Interfacial and microfailure properties of carbon liber/bismaleimide (BMI) composites were evaluated using both tensile fragmentation and compressive Broutman tests with acoustic emission (AE). Since BMI is rather difficult matrix to apply for the conventional fragmentation test because of its too low elongation and too brittle and high modulus properties, dual matrix composite system was applied. After carbon fiber/BMI composite was prepared for rod shape by controlling differing curing stage, composites rod was embedded in toughened epoxy as outer matrix. The typical microfailure modes including fiber break, matrix cracking, and interlayer failure were observed during tensile testing, whereas the diagonal slippage in fiber ends was observed during compressive test. On the other hand, AE amplitudes of BMI matrix fracture were higher than carbon fiber tincture under tensile test because BMI matrix has very brittle and high modulus. The waveform of signals coming from BMI matrix fractures was consistent with AE amplitude result under tensile tests.

• Journal of the Korea Safety Management & Science
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• v.12 no.3
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• pp.37-52
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• 2010

This study is aimed at proposing the national policy for medical device control system in Korea as deeply analysed the present status of the system. On 1979, Korean government had started to inspect 24 kinds of the medical devices such as X-ray diagnostic equipments, medical sterilizer and etc. mostly imported from advanced countries which USA, Germany and Japan for the first time according to the Pharmaceutical Affairs Law. However medical devices were becoming consideration as an important partner of diagnosis, curing and alleviation of diseases by medical doctors and also much important keeping the health at home. Furthermore medical devices industry can be designated as a national growth engine industry. So it is necessary not only to harmonize to international standards but also the harmonization of the system including pre-market application and post-market surveillance, is strongly needed by the Korea Food and Drugs Administration(KFDA).

• Bulletin of the Korean Chemical Society
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• v.33 no.7
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• pp.2224-2228
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• 2012

This study describes the ability of capillary electrochromatography (CEC) for the determination of imidacloprid and carbendazim in tomato samples. A novel liquid crystal crown ether modified hybrid silica monolithic column was synthesized, characterized and developed as separation column for the first time. Baseline separation of imidacloprid and carbendazim could be achieved using a mobile phase containing 90% (v/v) 20 mmol/L phosphate buffer (pH 7.0) and 10% (v/v) acetonitrile. The matrix matched calibration curves were linear with correlation coefficient $r^2$ > 0.9998 in the range of 0.20-10.00 mg/L. The limits of detection for imidacloprid and carbendazim were 0.061 and 0.15 mg/kg, respectively, which were below the maximum residue limits established by the European Union as well as Codex Alimentarius. Average recoveries for imidacloprid and carbendazim varied from 101.6-108.0% with relative standard deviations lower than 6.3%. This method was applied to the analysis of tomatoes collected from local markets.

• Earthquakes and Structures
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• v.8 no.3
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• pp.591-617
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• 2015

Standards for seismic assessment and retrofitting of buildings provide deformation limit states for structural members and connections. However, in order to perform fully consistent performance-based seismic analyses of soil-structure systems; deformation limit states must also be available for foundations that are vulnerable to nonlinear actions. Because such limit states have never been established in the past, a laboratory testing program was conducted to study the rotational capacity of small-scale foundation models under combined axial load and moment. Fourteen displacement-controlled monotonic and cyclic tests were performed using a cohesionless soil contained in a $2.0{\times}2.0{\times}1.2m$ container box. It was found that the foundation models exhibited a stable hysteretic behavior for imposed rotations exceeding 0.06 rad and that the measured foundation moment capacity complied well with Meyerhof's equivalent width concept. Simplified code-based soil-structure analyses of an 8-story building under an array of strong ground motions were also conducted to preliminary evaluate the implication of finite rotational capacity of vulnerable foundations. It was found that for the same soil as that of the experimental program foundations would have a deformation capacity that far exceeds the imposed rotational demands under the lateral load resisting members so yielding of the soil may constitute a reliable source of energy dissipation for the system.

• Nuclear Engineering and Technology
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• v.48 no.1
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• pp.200-210
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• 2016

The neutron radiography reactor (NRAD) is a 250 kW Mark-II Training, Research, Isotopes, General Atomics (TRIGA) reactor at Idaho National Laboratory, Idaho Falls, ID, USA. The East Radiography Station (ERS) is one of two neutron beams at the NRAD used for neutron radiography, which sits beneath a large hot cell and is primarily used for neutron radiography of highly radioactive objects. Additional fuel elements were added to the NRAD core in 2013 to increase the excess reactivity of the reactor, and may have changed some characteristics of the neutron beamline. This report discusses characterization of the neutron beamline following the addition of fuel to the NRAD. This work includes determination of the facility category according to the American Society for Testing and Materials (ASTM) standards, and also uses an array of gold foils to determine the neutron beam flux and evaluate the neutron beam profile. The NRAD ERS neutron beam is a Category I neutron radiography facility, the highest possible quality level according to the ASTM. Gold foil activation experiments show that the average neutron flux with length-to-diameter ratio (L/D) = 125 is $5.96{\times}10^6n/cm^2/s$ with a $2{\sigma}$ standard error of $2.90{\times}10^5n/cm^2/s$. The neutron beam profile can be considered flat for qualitative neutron radiographic evaluation purposes. However, the neutron beam profile should be taken into account for quantitative evaluation.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.18 no.3
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• pp.225-230
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• 2006

The overall performance and local flow fields of the fan, heat sink, and fan-sink were experimentally and numerically studied to investigate the flow characteristics of a fan-sink. The flow resistance of the heat sink was measured by small fan tester based on AMCA standards and compared with the CFD results to select available cooling fan for the fan-sink. The nonuniform velocity profile behind the fan outlet was shown by the flow visualization. The effects of nonuniform velocities on the performance of heat sink were discussed. To validate the commercial CFD code CFX-5.6, the predicted performance curve was compared with that of fan testing. The local flow fields of the fan-sink were analyzed by CFD results. MFR (multiple frame of reference) was used as a computational model combining rotating fan and stationary heat sink. Through the CFD results of the fan-sink, the flow patterns behind the fan outlet influenced the flow resistance and overall performance of the heat sink.

• Journal of the Korea Institute of Building Construction
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• v.10 no.6
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• pp.145-154
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• 2010

As buildings have become higher and larger, the use of high performance concrete has increased. With this increase, interest in and use of ultra fine powder admixture is also on the rise. The silica fume and BSF are the admixtures currently being used in Korea. However, silica fume is exclusively import dependent because it is not produced in Korea. In the case of BFS, it greatly improves concrete fluidity and long-term strength. But a problem exists in securing early strength. Furthermore, air-cooled slag is being discarded, buried in landfills, or used as road bed materials because of its low activation energy. Therefore, we investigated in this study the usability of nano-slag (both rapidly-chilled and air-cooled) as an alternative material to the silica fume. We conducted a physic-chemical analysis for the nano-slag powder and performed a mortar test to propose quality standards. The analysis and testing were done to find out the industrial usefulness of the BFS that has been grinded to the nano-level.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2013.11a
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• pp.179-182
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• 2013

Many kinds of fire-stop sealants have been used for joint sealing, cable penetration part sealing and fireproof structure finishing etc in building sectors which need water-proofing and fire-stop properties. But, fire-stop sealant itself has no specific industry standards in Korea even though there are so many required properties for the application. So, in this study, for the evaluation, we adopted and applied UL standard 94(UL 94) which is commonly used for the fire retardant testing in inflammable materials like plastics and rubbers in electronics industry. In this study, we demonstrated fire resistance properties of each fire-stop sealants which varied with different formulation, thickness and origins available in Korea. Overall, fire stop sealant had better fire resistance performance than normal construction sealant. And the thicker the material, the better the fire resistance performance was. Because there is no national or industry guideline for fire stop sealant itself, each sealant products showed different level of performances under UL94 desigation. Even certain product had very poor fire proof propeties although it claims it can be used for the application.

• KEPCO Journal on Electric Power and Energy
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• v.2 no.1
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• pp.33-41
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• 2016

To verify that the friction damper used to high buildings as a kind of control technology of wind vibration can reduce dynamic behaviors of PTTs effectively, slip dampers in this paper are proposed to absorb the energy through relatively frictional movement of slip dampers applied to main post of a PTT (Power Transmission Tower) when dynamic displacement of a PTT occurs. The result of dynamic analysis is presented to determine the capacity of the damper system by controlling damping ratio on the resonance condition. It is observed that by installing slip dampers at a PTT the strain amplitudes of the main post caused by wind load are effectively reduced. Therefore it is shown that the proposed damper satisfies the strengthened wind-load design standards, and its efficacy was also validated experimentally by field testing.

• Journal of Biomedical Engineering Research
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• v.29 no.1
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• pp.82-87
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• 2008

In this paper, the study was carried out to design and implement the medical compound stimulator based on the preexisting individual medical stimulators with Low frequency, High frequency and cooling stimulation. The proposed equipment is designed to compound all the functions including a cooling stimulation with a range of $0{\sim}20^{\circ}C$ and the verified low and high frequencies of 250Hz, 500Hz, 1KHz and 1MHz respectively from the previous clinical experiment with a consideration of its credibility and efficiency. Also, it was constructed by using a new technique, thermoelectricity semiconductor with a consideration of miniaturization and stability. In accordance with patients' treatment purpose, the hand piece of low frequency/cooling stimulation and High frequency/cooling stimulation were separately designed for convenience. The frequency, accuracy and other factors of implemented medical compound stimulator was satisfied according to its measurement. It was also tested by Korean Testing Laboratory (KTL) for its stability and efficacy and it confirmed that the medical compound stimulator is suitable for use as it fits in with the medical equipment standards.