• Bulletin of the Korean Chemical Society
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• v.25 no.1
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• pp.122-126
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• 2004

Biofunctional nanohybrids are synthesized from layered double hydroxide (LDH) and the vitamins such as ascorbic acid and topopherol acid succinate. Either ion exchange or copricipitaion leads to successful intercalation of the vitamins into gallery space of LDH that offers a new route to safe preservation of bioactivity as well as controlled release. Intercalations of vitamins are clearly reflected on the increase in the basal spacing of ZnAl-(Nitrate) LDH from 8.5 ${\AA}$ to 10.5 ${AA}$ for ascorbate, and 49.0 ${AA}$ for tocopherol acid succinate, respectively. No significant change in UV-Vis and IR absorption characteristics of the intercalated vitamins strongly supports the safe maintenance of their bioactivities without any deterioration of chemical and structural integrity. Furthermore, it is shown that the hybridized vitamins could be discharged in a controlled kinetics.

• Journal of the Korean Ceramic Society
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• v.49 no.2
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• pp.161-166
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• 2012

The temperature-rasing sintering method was used in this study to fabricate the aggregates of uniform pore size and distribution containing reject ash occurred in the thermal power plant. The spheric green aggregates made of reject ash were put into the box furnace of 800~$1000^{\circ}C$, heated with a heating rate of 5~$15^{\circ}C$/min to 1200~$1275^{\circ}C$, sintered for 10 min and then discharged out of the furnace to the room temperature. The input temperature, heating rate and sintering temperature increased the bloating phenomenon of the specimen, and the sintering temperature among them was the most effective factor. The aggregate manufactured at $1275^{\circ}C$ had the specific gravity of about 1.0 and water absorption of 1~2%, and the pores of 500~1,000 ${\mu}m$ were uniformly distributed across the whole specimen. Especially, the aggregates fabricated using the temperature-rasing sintering method in this study showed an excellent bloating properties and uniform microstructure without black core phenomenon which is typical for the bloated ceramics synthesized by direct sintering method.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.21 no.4
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• pp.195-205
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• 1988

Distribution of organic materials In the surface sediments was investigated in September 1983 in Chinhae Bay System. Bottom waters containing less than 1ml/l of dissolved oxygen were found in Masan Bay, and in part of Kohyonsong Bay and Wonmunpo Bay. Organic carbon content in the surface sediments of Masan Bay was about 25mg/g and it decreased with increasing distance from the inner Masan Bay. Mean organic carbon contents in Wonmunpo Bay and Kohyonsong Bay were 25.48 and 31.39mg/g, respectively, which are higher values than those in Masan Bay where large amount of domestic and industrial wastewaters art discharged into the surface water and extensive phytoplankton occurs almost year round. Mean organic nitrogen and pheophyton contents were also the highest in Kohyonsong Bay amont eight subareas. In Masan Bay, settling of organic materials on the surface sediments seemed to be not significant because of active tidal mixing and relatively small size of particulate materials. In Kohyonsong Bay and Wonmunpo Bay large fecal pellets produced in shellfish farms could be easily settled down on the sediment because of weak current regime. DO content in the bottom waters were low in the organic material rich areas, and that suggests biodegradation of organic materials in the surface sediments could be an important oxygen consuming process during the study period of September 1983.

• Ceramist
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• v.22 no.2
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• pp.198-214
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• 2019

The possibility of economic exchange with North Korea is increasing, but there is still a shortage of information of cement industry, which occupies the largest proportion of North Korean construction material industry. Therefore, this study researched the status of cement production facility management using satellite photographs of 16 cement factories in North Korea, and examined the operating status of North Korean cement industry by observing smoke discharged from the chimneys of the cement production facilities. When the satellite photographs were analyzed, it was observed that the monthly stack fog ratio of the North Korean cement factories was 55% in 2016, 60% in 2017 and nearly 65% in 2018. This demonstrates that the average operating ratio has been increasing continuously. However, the operation rate of the five major cement factories reaches the limit, actual cement production is estimated to have maintained the previous level or small increased.

• Proceedings of the Materials Research Society of Korea Conference
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• 2003.11a
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• pp.209-209
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• 2003

The adventages of Li alloys have attracted the attention of many research groups, many of which have investigated tin-based alloys [1-2], Despite interesting performances of these, the irreversible capacity loss systematically observed on the first cycle for these compounds is a main drawback for their use as anode materials in lithium ion cells. Not only Sn is efficient in forming alloys with Li, Si can also react with Li to form alloys with a high Li/Si ratio, like Li$\_$22/Si$\_$5/ at 400$^{\circ}C$. It corresponds to a capacity of 4200mAh/g. Electrochemical Li-Si reaction occurs between 0 and 0.3 V against Li/Li$\^$+/, so that high-energy density battery can be realized. Despite the high theoretical capacity of elements like Si, however, particles of the alloys crack and fragment due to the repeated alloying and do-alloying which occurs as cell are charged and discharged. The research groups of Muggins [3] and Besenhard [4] have proposed that the volume expansion due to the insertion of Li can be reduced in micro- and submicro-structured matrix alloys. For this reason, the research group of J.R. Dahn investigated Sn/Mo sequential sputter deposition to prepare nanocomposites [5]. In this study, we investigated the characterization and the electrochemical characteristics of sequentially sputtered Si/Mo multilayer for microbattery anode.

• 한국전기화학회:학술대회논문집
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• 1998.12a
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• pp.7-27
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• 1998

In order to design capacity of lithium ion battery, some calculations were carried out based on the characteristics of materials by the given battery shape and dimension. The principle of design was built by the interpretation of the correlation of material, electrochemical and battery factors. Parameters of materials are fundamental physical properties of constituent such as cathode. separator, anode, current collectors and electrolyte. Electrochemical factor includes potential pattern as a function of specific capacity, specific discharge capacity(or initial irreversible specific capacity or Ah efficiency) as a function of specific charge capacity and material balancing. Parameters of battery are dimension, construction hardware and performance. Battery capacity was simulated for a lithium cobalt dioxide as cathode and a hard carbon as anode to achieve 1100 mAh for the charge limit voltage of 4.2V, the weight ratio(+/-) of 2.4 and ICR18650. A fabricated test cell (ICR18650) which have weight ratio(+/-) of 2.4 discharged to 1093 mAh for the charge limit voltage of 4.2V. The sequential discharge capacity show good correspondence with designed capacity.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.28 no.4
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• pp.42-48
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• 2014

Sewage treatment facilities can purify sewage enough to be send to river or sea water, that discharged from human life and industrial activities. In the sewage treatment process, we can get large amount of by-product energy resources and materials such as heat of sewage, digester gas and purified water etc., it can be utilized by applying various technologies thereby we can reduce energy consumption in the process. In this paper, it was analyzed using the data collected from the operational case study for the energy savings effect that can be obtained when using the digester gas, one of the by-product materials of sewage treatment process, for electric power generation. Cost of 623million won is an annual reduction of 4,032MWh corresponding 9% of the annual electricity consumption of the sewage treatment plant, such an alternative power generation using digester gas was proposed in this paper has been verified the feasibility of the proposed reduction of energy.

• Journal of Environmental Health Sciences
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• v.34 no.3
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• pp.219-225
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• 2008

Many building materials may contain high concentrations of volatile organic compounds (VOCs) and other hazardous pollutants(HAPs). Specifically, VOCs discharged by indoor building material may cause "new house" syndrome, atopic dermatitis etc. The diffusion coefficient and initially contained total VOC quantity were determined using microbalance experiments and small chamber tests. Interactions between volatile organic compounds (VOCs) and vinyl flooring (VF), a relatively homogenous, diffusion-controlled building material, were characterized. Rapid determination of the material/air partition coefficient (K) and the material-phase diffusion coefficient (D) for each VOC was achieved by placing thin VF slabs in a dynamic microbalance and subjecting them to controlled sorption/desorption cycles. K and D are shown to be independent of concentration for all of the VOCs and water vapor. This approach can be applied to other diffusion-controlled materials and should facilitate the prediction of their source/sink behavior using physically-based models.

• Korean Journal of Metals and Materials
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• v.47 no.8
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• pp.488-493
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• 2009

Direct syntheses of bulk $Ti_3Al$ via electro-discharge-sintering (EDS) of a stoichiometric elemental powder mixture were investigated. A capacitor bank of $450{\mu}F$ was charged with three input energies, 0.5, 1.0, and 1.5 kJ. The charged capacitor bank was then instantaneously discharged through 0.3 g of a Ti-25.0 at.%Al powder mixture for consolidation. Complete phase transformation occurred in less than $200{\mu}sec$ by the discharge and a bulk $Ti_3Al$ compact was obtained. Compared with consolidated samples fabricated by conventional methods such as high vacuum sintering and casting, the electro-discharge-sintered $Ti_3Al$ compact shows a very fine microstructure with a hardness value of 425 Hv. Electro-discharge-sintering under a $N_2$ atmosphere successfully modified the surface Ti oxide of the $Ti_3Al$ compact into Ti nitride, which concurred with the synthesis and consolidation of $Ti_3Al$. Complete conversion yielding a single phase $Ti_3Al$ is primarily dominated by the fast solid state diffusion reaction.

• Journal of Powder Materials
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• v.18 no.2
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• pp.149-158
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• 2011

Electro-Discharge Sintering (EDS) employs a high-voltage/high-current-density pulse of electrical energy, discharged from a capacitor bank, to instantaneously consolidate powders. In the present study, a single pulse of 0.57-1.1 kJ/0.45 g-atomized spherical $Ti_{52}Zr_{28}Ni_{20}$ powders in size range of 10~30 and $30\sim50{\mu}m$ consisting of ${\beta}$-(Ti, Zr) and icosahedral phases were applied to examine the structural evolution of icosahedral phase during EDS. Structural investigation reveals that high electrical input energy facilitates complete decomposition of icosahedral phase into C14 laves and ${\beta}$-(Ti, Zr) phases. Moreover, critical input energy inducing decomposition of the icosahedral phase during EDS depends on the size of the powder. Porous Ti and W compacts have been fabricated by EDS using rectangular and spherical powders upon various input energy at a constant capacitance of $450{\mu}F$ in order to verify influence of powder shape on microstructure of porous compacts. Besides, generated heat (${\Delta}H$) during EDS, which is measured by an oscilloscope, is closely correlated with powder size.