• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.11
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• pp.3260-3268
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• 2009

A test apparatus has been fabricated to simulate chemical effect on head loss through a strainer in a pressurized water reactor (PWR) containment water pool after a loss of coolant accident (LOCA). Tests were conducted under condition of same ratio of strainer surface area to water volume between the test appratus and the containment sump. A series of tests have been performed to investigate the effects of spray, existence of calcium-silicate with tri-sodium phosphate (TSP), and composition of materials. The results showed that head loss across the chemical bed with even a small amount of calcium-silicate insulation instantaneously increased as soon as TSP was added to the test solution. Also, the head loss across the test screen is strongly affected by spray duration and is increased rapidly at the early stage, because of high dissolution and precipitation of aluminum and zinc. After passivation of aluminum and zinc by corrosion, the head loss increase is much slowed down and is mainly induced by materials such as calcium, silicon, and magnesium leached from NUKONTM and concrete. Furthermore, it is newly found that the spay buffer agent, tri-sodium phosphate, to form protective coating on the aluminum surface and reduce aluminum leaching is not effective for a large amount of aluminum and a long spray.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.43 no.9
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• pp.822-829
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• 2015

In this paper, the piezoelectric-hydraulic pump with a piezostack actuator as a driving source has been designed, fabricated, and evaluated for its application to UAV's brake system. The performance requirements of the piezoelectric-hydraulic pump were decided based on the requirements analysis of the target aircraft brake system. The geometric design of the piezoelectric-hydraulic pump to meet the performance requirements of the pump was conducted, and all components of the pump including the spring sheet type check valves were machined with close tolerance. By constructing a test apparatus for the performance check of the piezoelectric-hydraulic pump, the performance characteristics of the pump, such as the outlet flow rate for load-free condition and the outlet oil pressure for closed loop condition, have been evaluated. It has been found by the performance test result that the developed piezoelectric-hydraulic pump satisfies the design requirements effectively.

• Journal of Energy Engineering
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• v.24 no.4
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• pp.124-129
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• 2015

An experimental study was performed estimating COP(Coefficient of Performance) of air-conditioning cycle using inverter scroll compressor with and without $Al_2O_3$ nano particle. All experiments were done for various compressor speeds from 1000~4000 rpm and used the inverter controller called CANDY to change the compressor rpm. The air-conditioning cycle components in the apparatus were used as same with components of YF hybrid car. To estimate the COP, this study measured the temperature and pressure at inlets and outlets of compressor, condenser, and evaporator. And also measured the compressor input power using Powermeter. Through the experiments, the maximum error to estimate COP was shown about ${\pm}6.09%$ at 3500rpm. The COP of refrigeration cycle with $Al_2O_3$ nano-particle was similar with that of the base cycle without nano-particle between 1000~3000 rpm of the compressor speed. But, This study showed that the COP of the cycle with $Al_2O_3$ over 3000 rpm of the compressor speed was higher than that of the base cycle due to the higher heat transfer rate increased in the evaporator from the higher oil flow rate inside the cycle as well known. Those results can be used the basic and fundamental data to design the air-conditioning cycle using inverter scroll compressor with $Al_2O_3$ nano particle.

• Journal of Energy Engineering
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• v.26 no.3
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• pp.105-112
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• 2017

A lot of piping systems have been used from nuclear power systems to water supply systems. The maintenance of the piping systems is needed to ensure proper operation of the piping systems. Failure of the large pipe systems especially such as KDHC(Korea District Heating Corporation) can be a matter directly related to the enterprise productivity and profitability. It can also lead to very important issues in promoting public safety and convenience. Therefore a method of quick and safety repairs have been emerged as the most important problem. In this study, freezing seal isolation method using liquid nitrogen cryogenic refrigerant was developed for the maintenance of a pre insulated heat transport pipe of KDHC with a diameter of 300 mm. In this study, by employing computational analysis techniques we performed the flow and heat transfer analysis for the targeted pre insulated heat transfer pipe and freezing seal jacket(ice-Plug) and have selected for optimal system. The detailed design model based on the results of the computational analysis finally was produced. A laboratory-scale test apparatus were designed and the freezing seal isolation self-test carried out. Also the performance assessment tests in the test bed of KDHC were carried out for on-site application.

• Applied Microscopy
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• v.21 no.1
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• pp.1-20
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• 1991

The effects of exogenous $Ca^{2+}$ stimulation on the post-ischemic myocardial cells were studied using isolated Langendorff-perfused guinea pig hearts. At the starting point of reperfusion, Tyrode solutions, each containing 2.0mM, 4.0mM and 8.0mM $CaCl_2$ respectively, were administered for 2 minutes apart by descending, ascending, or by combined sequences followed by standard Tyrode solution containing 1.0mM $CaCl_2$. The minutes of global ischemia produced reversible but moderate to severe degree of myocardial ultrastructrual changes including focal destruction of sarcolemma, loss of nuclear matrix, clumping and margination of chromatins, mitochondrial swelling, destruction of mitochondrial cristae, shortening of sarcomeres, focal loss of myofibrils, and separation of cell junctions. In spite of reperfusion, the ultrastructure was more severely damaged and irreversible changes such as intracellular fluid accumulation, contracted sarcomeres, mitochondrial destruction, disruption of sarcolemma, loss of nuclear matrix, and separation of cell junction were observed in a large number of cells. In contrast, Tyrode-perfused $Ca^{2+}$-stimulated myocardial cells showed relatively well preserved ultrastucture, except slight changes including focal mitochondrial swelling, widening of T-tubule, and widening of cell junctions, especially at fasciae adherentes. The post-ischemic $Ca^{2+}$-stimulated reperfused myocardial cells produced focal changes such as mitochondrial destruction, disintegration of sarcolemma, widening of T-tubule, and intracellular fluid accumulation with slight variation in degree of changes by the method of $Ca^{2+}$ administration sequence. However, in a large number of the myocardial cells, chromatins were redistributed relatively evenly in the nuclear matrix, mitochondrial cristae were tightly packed, and a considerable number of intramitochondrial granules and glycogen granules reap-pealed. These results indicate that exogenous $Ca^{2+}$ stimulation in the initial period of reperfusion may be beneficial to salvage or to reduce the post-ischemic myocardium from further deleterious changes, and that the beneficial effects may be derived from the reserves of the function of the intracellular $Ca^{2+}$ regulating organelles and/or from the responsiveness of contractile apparatus to $Ca^{2+}$ stimulation.

• Applied Chemistry for Engineering
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• v.9 no.4
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• pp.504-508
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• 1998

Experimental investigation on the adsorption of heavy metal confounds as $Fe^{2+}$, $Cu^{2+}$, $Mn^{2+}$, $Zn^{2+}$, $Ni^{2+}$, $Pb^{2+}$, $Cd^{2+}$, $Cr^{6+}$ using chitosan was carried out. The adsorption of each component of heavy metal compounds was measured by Atomic Absorption apparatus. The range of optimum pH for the removal rates of heavy metal compounds was found pH 7.0~9.0. The maximum time for the removal rate of $Fe^{2+}$ was observed about 15 min. The maximum time for the removal raters of $Cu^{2+}$, $Mn^{2+}$, $Zn^{2+}$, $Ni^{2+}$, $Pb^{2+}$, $Cd^{2+}$, and $Cr^{6+}$ was observed about 25 min. The adsorption rates of heavy metal compounds by chitosan have been found in the order of $Fe^{2+}>Cu^{2+}>Mn^{2+}>Zn^{2+}>Ni^{2+}>Pb^{2+}>Cd^{2+}>Cr^{6+}$.

• Korean Journal of Agricultural and Forest Meteorology
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• v.7 no.4
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• pp.296-302
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• 2005

We investigated changes in photosynthetic characteristics of P. davidiana in order to understand damage patterns to photosynthetic apparatus under drought stress. Root sprout saplings of P. davildiana were treated with $0\%,\;2\%,\;5\%,\;and\;10\%$ of 300ml polyethylene glycol (PEG) once a weer far one month. After one month, we measured photosynthetic parameters and analyzed the photochemical and $CO_2$ fixation systems. Photosynthetic rate, stomatal conductance, and respiration rate in the leaves of P. davildiana decreased according to increasing stress strength. In the photochemical system, quantum yield of PSII was reduced by the increment of PEG concentration, The decrease of apparent quantum yield was related to reduction of electron transport. Respiration rate decreased with an increase in PEG concentration, whereas photorespiration rate in the $CO_2$ fixation system increased. In conclusion, photosynthesis of P. davidiana responded sensitively under drought stress, and the sensitivity depended upon the strength of water stress. P. davidiana exhibited an increase of water use efficiency under water stress.

• Korean Journal of Environmental Agriculture
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• v.1 no.1
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• pp.48-52
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• 1982

Methods for the measurement of aquatic bacteria can be divided into two groups. The first group of these methods is based on the 'replicon' concept that live bacterial cells, when diluted and transferred to a suitable medium, produce colonies. These methods distinguish living from dead bacteria, but they massively underestimate bacterial numbers. The second group of enumeration methods uses visual counting technique using specific apparatus such as a microscope. These methods are generally direct and simple, but it is very hard to distinguish between live and dead bacteria and between small particle and bacteria. Recently developed technique in staining methods has provided a reliable method of visual determination of aquatic bacteria. This uses epifluorescence microscopy to measure the total bacterial population. In order to present the fluorescence microscopy as a new methodology for the determination of bacterial numbers in water supplies, data were obtained from chlorine and monochloramine doses added to samples. Total counts by fluorescence microscopy were compared with standard plate count method. The total number of bacteria in water supplies can be determined with fluorescence microscopy. This technique allows better resolution of small bacteria and differentiation of particle from bacteria. Chloramine was found to persist longer in natural waters and prevent bacterial regrowth.

• Journal of Korea Port Economic Association
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• v.31 no.3
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• pp.141-153
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• 2015

This paper is an attempt to analyze the comparative advantage of Busan Port to China. For this, we use the market comparative advantage index, which is a version of the revealed comparative advantage index. The market comparative advantage index (MCA) uses trade patterns to identify the sectors in which a region has a comparative advantage, in this case by comparing Busan Port's trade profile with the world average (China). The indices are calculated at the commodity level of the HS four-digit classification. The export data used in this study are obtained from the Korea International Trade Association. Exports to China accounted for almost one third of Korean exports in 2014. There are, however, structural differences among the main export items of Busan Port. This paper, therefore, employs MCA indices to reveal the behaviors of the ten main export items, which are "HS3920-other plates/sheets/film/foil of plastics," "HS7606-aluminum plates/sheets/strip," "HS8479-unspecified machines/medical appliances," "HS8486-machines for semiconductor devices or wafers," "HS8529-parts for transmission apparatus for television," "HS8703-motor vehicles for the transport of persons," "HS8708-parts of motor vehicles," "HS9001-optical fibers," and "HS9013-liquid crystal devices." The study shows that export competitiveness of nine items increases, the exception being HS8703. However, China's import ratios of seven of the nine items for which the MCA indices go up are on the decrease, which means that it would be hard to expand the export market for these seven items, despite the higher MCA indices. Since the shares of the port's total exports to China of HS3907, HS8486, HS8529, HS9001, and HS9013 in total exports to China increase together with China's import ratio decreasing, these items may have promising export markets. MCA increases of HS7606 and HS8479 are attributable to China's lower import ratio, rather than a higher export share, so higher MCA indices do not guarantee higher export competitiveness for these items.

• Journal of the Institute of Convergence Signal Processing
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• v.19 no.2
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• pp.68-76
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• 2018

In this paper, we describe the correlation processing method of multi-polarization observation data of the Daejeon Correlator. VLBI observations include single or multiple polarized observations depending on the type of object. Polarization observations are performed to observe the characteristics of the object. During the observations of the celestial object, polarization measurements are also performed to determine the delay values and causes of changes in the object. Correlation processing of polarization observation data of the Daejeon correlator is proposed by OCTAVIA of a synchronous reproduction processing apparatus that outputs data input to each antenna unit by using an output bit selection function to convert bits and the order of the data streams is changed, And the input of the Daejeon correlator is configured to perform the polarization correlation processing by conducting correlation processing by setting the existing stream number to be the same. Correlation processing is conducted on the test data observed for the polarization correlation processing and it is verified through experiments that the polarization correlation processing method of the proposed Daejeon correlator is effective.