• Transactions of the Korean hydrogen and new energy society
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• v.13 no.4
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• pp.270-278
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• 2002

Mg and Mg alloys are attractive hydrogen storage materials because of their lightweight and high absorption capacity. Their range of applications could be further extended if their hydrogenation properties and degradation behavior could be improved, The main emphasis of this study was to find an economic manufacturing method for Mg-Ti-Ni-H systems, and to investigate their hydrogenation properties, In order to examine hydrogenation behavior, a Sieverts type automatic pressure-composition-isotherm(PCI) apparatus was used and the experiments were performed at 423, 473, 523, 573, 623 and 673K. The results of thermogravimetric analysis(TGA) reveal that the absorbed hydrogen contents are around 2.5 wt% for ($Mg_9Ti_1$)-10 wt% Ni. With increased Ni content, the absorbed hydrogen content decreases to 1.7 wt%, whereas the dehydriding starting temperatures are lowered by some 70-100K. The results of PCI on ($Mg_9Ti_1$)-20 wt% Ni show that its hydrogen capacity is around 5.3 wt% and its reversible capacity and plateau pressure are also excellent at 523K and 573K. In addition, the reaction enthalpy, $\Delta$HD.plateau, is $30.6{\pm}5.7kJ/molH_2$.

• Korean Journal of Materials Research
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• v.20 no.10
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• pp.543-549
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• 2010

The hydrogen energy had recognized clean and high efficiency energy source. The research field of hydrogen energy was production, storage, application and transport. The commercial storage method was using high pressure tanks but it was not safety. However metal hydride was very safety due to high chemical stability. Mg and Mg alloys are attractive as hydrogen storage materials because of their lightweight and high absorption capacity (about 7.6 wt%). Their range of applications could be further extended if their hydrogenation properties and degradation behavior could be improved. The main emphasis of this study was to find an economical manufacturing method for Mg-Ti-Ni-H systems, and to investigate their hydrogenation properties. In order to examine their hydrogenation behavior, a Sievert's type automatic pressure-compositionisotherm (PCI) apparatus was used and experiments were performed at 423, 473, 523, 573, 623 and 673 K. The results of the thermogravimetric analysis (TGA) revealed that the absorbed hydrogen contents were around 2.5wt.% for (Mg8Ti2)-10 wt.%Ni. With an increasing Ni content, the absorbed hydrogen content decreased to 1.7 wt%, whereas the dehydriding starting temperatures were lowered by some 70-100 K. The results of PCI on (Mg8Ti2)-20 wt.%Ni showed that its hydrogen capacity was around 5.5 wt% and its reversible capacity and plateau pressure were also excellent at 623 K and 673 K.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2001.05a
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• pp.106-111
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• 2001

The performance characteristics of heat pump system using the new refrigerant subcooling system were investigated. The new heat pump system has the ice storage tank to accumulate the latent heat of the refrigerant during the night-time. The heat is released to subcool the saturated refrigerant liquid at the outlet of a condenser in the daytime. The experimental apparatus is a well-instrumented heat pump which consisted of a refrigerant loop and a coolant loop. The test sections(condenser and evaporator) were made of tube-in-tube heat exchanger with the horizontal copper tube of 12.7[mm] outer diameter and 9.5[mm] inner diameter. The evaporating temperatures ranged from $-5[^{\circ}C]$ to $0[^{\circ}C]$ and the subcooling degrees of the refrigerant varied from $15[^{\circ}C]$ to $25[^{\circ}C]$. The test of the ice storage was carried out at evaporating temperature of $-10[^{\circ}C]$ and the ice storage mode is an ice-on-coil type. The main results were summarized as follows ; The refrigerant mass flow rate and compressor shaft power of the heat pump system were independent of the subcooling degrees. The cooling capacity o the heat pump system increases as the evaporating temperature and subcooling degree increases. The cooling capacity of the heat pump system is about 25 to 30% higher than that of normal heat pump system. The COP of the heat pump system which subcooled the refrigerant liquid at the outlet of the condenser is about 28% higher than that of the normal heat pump system.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.1
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• pp.69-73
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• 2013

Internal heat exchanger (IHX) apparatus using the temperature difference between high and low pressure lines in vehicle air conditioning system is a good method to enhance the cooling performance. In this study, we designed various double-pipe internal heat exchangers which have inner fins between the internal pipe and external pipe. We also measured the performance characteristic (pressure drop, cooling capacity, compressor work and coefficient of performance (COP)) of the modified internal heat exchangers that had the change of the fin height and the inside shape of the internal pipe. This experimental results indicated that the liner and serration type internal heat exchanger was the best cooling performance. In addition, the air conditioning system with the liner and serration type internal heat exchanger showed the improved performances of about 6.4% and 9.2%, respectively, for the cooling capacity and COP.

• Journal of Photoscience
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• v.12 no.1
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• pp.33-39
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• 2005

Plants possess the ability to dissipate the excitation energy for the protection of photosynthetic apparatus from absorbed excess light. Heat dissipation is regulated by xanthophyll cycle in thylakoid membranes of chloroplasts. We investigated the mechanistic aspects of xanthophyll cycle-dependent photoprotection against low-temperature photoinhibition in plants. Using barley and rice as chilling-resistant species and sensitive ones, respectively, chilling-induced chlorophyll fluorescence quenching, composition of xanthophyll cycle pigments and mRNA expression of the zeaxanthin epoxidase were examined. Chilled barley plants exhibited little changes in chlorophyll fluorescence quenching either of photochemical or non-photochemical nature and in the photosynthetic electron transport, indicating low reduction state of PS II primary electron acceptor. In contrast to the barley, chilled rice showed a marked decline in those parameters mentioned above, indicating the increased reduction state of PS II primary electron acceptor. In addition, barley plants were shown to have a higher capacity to elevate the pool size of xanthophyll cycle pigments in response to cold stress compared to rice plants. Such species-dependent regulation of xanthophyll cycle activity was correlated with the gene expression level of cold-induced zeaxanthin epoxidase. Chilled rice plants depressed the gene expression of zeaxanthin epoxidase, whereas barley increased its expression in response to cold stress. We suggest that chilling-induced alterations in the pool size of xanthophyll cycle pigments related to its capacity would play an important role in regulating plant's sensitivity to chilling stress.

• Transactions of the Korean hydrogen and new energy society
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• v.16 no.3
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• pp.238-243
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• 2005

Mg and Mg-based alloys are most important hydrogen storage materials. It is a lightweight and low-cost materials with high hydrogen storage capacity. However, the formation of hydride at high temperature, the deterioration effect, the hydriding and dehydriding kinetics are bad factor for application. In this study, Mg and Ni have been produced by hydrogen induced mechanical alloying(HIMA) process. The raw materials, Mg(purity 99.9%) chip and Ni(purity 99.95%) chip was prepared by using a planetary ball mill apparatus(FRITSCH pulverisette 5). The balls to chips mass ratio(BCR) are 30:1. The hydrogen pressure induced 2.0MPa and milling times were 12, 24, 48, 72, 96 hours with a rotating speed of 200rpm. X-ray diffraction(XRD) analysis was made to characterize the crystallite size and misfit strain. The crystallite size measured by laser particle size analysis(PSA). Microstructure changes were investigated by scanning electron microscopy(SEM) and the transmission electron microscopy(TEM). The hydrogen storage properties were evaluated by using an Sivert's type automatic pressure-composition-therm(PCT) apparatus.

• Journal of The Korean Society of Agricultural Engineers
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• v.51 no.5
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• pp.19-24
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• 2009

This study was conducted to provide fundamental data for design of air inflating apparatus of air-inflated double-layer plastic greenhouse. The variation of static pressure in air tube for different fans and filters, filtering performance for various kinds of filters and destruction phase of experimental greenhouse collapsed by excessive static pressure in air space were analyzed. The general type of forward centrifugal fan was recommended for inflating air space in air-inflated double-layer plastic greenhouse. The experimental greenhouse was collapsed down by excessive static pressure just like fallen by heavy snow load acting on it. The static pressure in air tube without filter decreased linearly as the number of outlet openings increased. But the pressure in air tube with filter declined quadratically, the decremental ratio diminished by the increase of outlet openings. The higher filtering efficiency and the greater decrements of static pressure in air tube, the larger capacity fan was required for maintaining proper static pressure in air space. Because the porosities of filter were blocked by dust as time goes by, the static pressure in air tube with filter decreased. The higher filtering efficiency, the less decremental ratio of static pressure in air tube as time passes by. Considering the filtering efficiency, decrement of static pressure and thickness of filter, the 5mm thickness filter of 75% efficiency was recommended for air inflating filter of air-inflated double-layer plastic greenhouse.

• ALGAE
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• v.20 no.2
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• pp.121-125
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• 2005

The modern integrated fish-seaweed mariculture has been tested to reduce the environmental impacts of an intensive fed culture. To obtain the best seaweed bioremediation performance, the effects of therapeutants used for fish disease control on the selected seaweed species should be considered. As a selected seaweed, Porphyra yezoensis was tested with six commercial antibiotics including erythromycin thiocyanate_A, erythromycin thiocyanate_B, oxytetracycline, doxycycline, pefloxacin, and amoxicillin trihydrate under the batch incubation at a photon flux density of 10 $\mu$mol ${\cdot}m^{-2}\;{\cdot}\;s^{-1}$ at 15$^{\circ}C$. Among the tested commercial antibiotics, erythromycin thiocyanate_A, erythromycin thiocyanate_B, oxytetracycline, and doxycycline showed decreases in Fv/Fm, the photochemical efficiency of photosystem II, with a dose-dependant and time-dependant manner. From the quenching analysis of chlorophyll fluorescence, three differential patterns were observed in the antibiotics-treated Porphyra: (1) high nonphotochemical quenching (NPQ) and low photochemical quenching (qP) in the cases of Erythromycin thiocyanate_B and amoxicillin trihydrate, (2) high NPQ and high qP in the case of pefloxacin and (3) low NPQ and low qP in the case of oxytetracycline. These results indicated that antibiotics affected in various ways on the photosynthetic apparatus, reflecting differential lesion sites of antibiotics. In addition, the rates of ammonium uptake also decreased with a decrease of Fv/Fm in P. yezoensis thalli treated with erythromycin thiocyanate_B and oxytetracycline. Therefore, the four antibiotics mentioned could affect the bioremediation capacity of the selected seaweed species in the integrated fish-seaweed mariculture system due to the decrease of photosynthetic activity and the simultaneous decrease of ammonium uptake.

• International Journal of Computer Science & Network Security
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• v.22 no.10
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• pp.113-130
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• 2022

Sophisticated automation-based electronics world, more electrical and electronic devices are being used by people from different regions across the universe. Different manufacturers and vendors develop and market a wide variety of power generation and utilization devices under different operating parameters and conditions. People use a variety of appliances which use electrical energy as power source. These appliances or gadgets utilize the generated energy in different ratios. Night time the utilization will be less when compared with day time utilization of power. In industrial areas especially mechanical industries or Heavy machinery usage regions power utilization will be a diverse at different time intervals and it vary dynamically. This always causes a fluctuation in the grid lines because of the random and intermittent use of these apparatus while the power generating apparatus is made to operate to provide a steady output. Hence it necessitates designing and developing a method to optimize the power generated and the power utilized. Lot of methodologies has been proposed in the recent years for effective optimization and economical load dispatch. One such technique based on intelligent and evolutionary based is Black Widow Optimization BWO. To enhance the optimization level BWO is hybridized. In this research BWO based optimize the load for multi area is proposed to optimize the cost function. A three type of system was compared for economic loads of 16, 40, and 120 units. In this research work, BWO is used to improve the convergence rate and is proven statistically best in comparison to other algorithms such as HSLSO, CGBABC, SFS, ISFS. Also, BWO algorithm best optimize the cost parameter so that dynamically the load and the cost can be controlled simultaneously and hence effectively the generated power is maximum utilized at different time intervals with different load capacity in different regions of utilization.

• Korean Chemical Engineering Research
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• v.53 no.1
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• pp.57-63
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• 2015

Absorption characteristics of 2-methylpiperidine (2MPD), 3-methylpiperidine (3MPD) and 4-methylpiperidine (4MPD) absorbents were studied by a vapor-liquid equilibrium (VLE) apparatus and a differential reaction calorimeter (DRC). Using a VLE apparatus, the $CO_2$ loading capacity of each absorbent was estimated. After reaching the absorption equilibrium, nuclear magnetic resonance spectroscopy (NMR) had been conducted to characterize the species distribution of the ($H_2O$-piperidine-$CO_2$) system. Using a DRC, the reaction of heat was confirmed in accordance with the absorption capacity. The unique characteristics of 2MPD, 3MPD and 4MPD absorbents appeared by the position of methyl group. The 2MPD possessing the methyl group at the ortho position showed its hindrance effect during the absorption process; however, piperidine derivatives possessing the meta position and para position did not show its characteristics in $H_2O$-piperidine-$CO_2$ system.