• KSBB Journal
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• v.21 no.5
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• pp.336-340
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• 2006

High-density perfusion cultivation was performed to produce extracellular polysaccharide(ECP) as immunostimulating agents in suspension cell cultures of Angelica gigas Nakai. In batch culture, the maximum cell density was 16.8 gDCW/L at day 6 and 0.9 g/L of ECP was obtained at day 8. When the medium exchange was started at the fifth day after inoculation for the perfusion culture, high concentration of the cells at 23.8 gDCW/L could be achieved with continuous production of ECP. Treatments of ultrasound and Pluronic F-68 were found to be helpful for the secretion of intracellular ECP into the culture medium.

• Korean Journal of Environmental Biology
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• v.29 no.1
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• pp.46-51
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• 2011

Distributional patterns of benthic microalgae were studied in the tidal flats of Saemangeum lake, Korea, from March 2007 to October 2009. As benthic microalgae of tidal flats of Saemangeum lake, 44 species belong to 5 classes were identified. Diatoms predominated the benthic microalgal flora with 75.0% of total species occurred. Dominant species were Achnanthes lanceolata, Aulacoseira granulata, Cymbella tumida, Fragilaria construens var. ventor, Melosira varians, Navicula cryptocephala, Navicula cryptocephala var. veneta, Nitzschia palea, and Paralia sulcata. The cell density and biomass of benthic microalgae were highest in 2009, and clear tendency of increment was observed at D1 and D2 sites. In vertical profiles, cell density and biomass of the benthic microalgae showed maximum cells and biomass at 0~1 mm depth of sediments from all sampled sites.

• Korean Journal of Veterinary Research
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• v.32 no.1
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• pp.77-82
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• 1992

A noncytopathic bovine viral diarrhea virus(NC BVDV) strain isolated and purified from persistently infected primary bovine fetal lung(BFL) cells was studied by biophysical methods. The buoyant density of particles of the NC BVDV strain was shown to be between 1,090 and $1,114g/cm^3$ and the maximum virus infectivity occured at $1,098g/cm^3$. Immunoelectron microscopic examination by using the partially purified virus revealed regular spherical particles 30~80nm in diameter. Differences in the genomic size of cytopathic and noncytopathic BVDV from infected cells were not found. A comparison of viral proteins of a noncytopathic and cytopathic strain(NADL) by immunoprecipitation using monoclonal antibody indicated that NC BVDV, compared to cytopathic NADL, was cell associated.

• Journal of Surface Science and Engineering
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• v.49 no.2
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• pp.159-165
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• 2016

The hydrogen has been recognized as a clean, nonpolluting and unlimited energy source that can solve fossil fuel depletion and environmental pollution problems at the same time. Water electrolysis has been the most attractive technology in a way to produce hydrogen because it does not emit any pollutants compared to other method such as natural gas steam reforming and coal gasification etc. In order to improve efficiency and durability of the water electrolysis, comprehensive studies for highly active and stable electrocatalysts have been performed. The platinum group metal (PGM; Pt, Ru, Pd, Rh, etc.) electrocatalysts indicated a higher activity and stability compared with other transition metals in harsh condition such as acid solution. It is necessary to develop inexpensive non-noble metal catalysts such as transition metal oxides because the PGM catalysts is expensive materials with insufficient it's reserves. The optimization of operating parameter and the components is also important factor to develop an efficient water electrolysis cell. In this study, we optimized the operating parameter and components such as the type of AEM and density of gas diffusion layer (GDL) and the temperature/concentration of the electrolyte solution for the anion exchange membrane water electrolysis cell (AEMWEC) with the transition metal oxide alloy anode and cathode electrocatalysts. The maximum current density was $345.8mA/cm^2$ with parameter and component optimization.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.13 no.3
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• pp.1325-1344
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• 2019

Recently, to satisfy mobile users' increasing data transmission requirement, energy efficiency (EE) resource allocation in distributed antenna systems (DASs) has become a hot topic. In this paper, we aim to maximize EE in DASs subject to constraints of the minimum data rate requirement and the maximum transmission power of distributed antenna units (DAUs) with different density distributions. Virtual cell is defined as DAUs selected by the same user equipment (UE) and the size of virtual cells is dependent on the number of subcarriers and the transmission power. Specifically, the selection rule of DAUs is depended on different scenarios. We develop two scenarios based on the density of DAUs, namely, the sparse scenario and the dense scenario. In the sparse scenario, each DAU can only be selected by one UE to avoid co-channel interference. In order to make the original non-convex optimization problem tractable, we transform it into an equivalent fractional programming and solve by the following two sub-problems: optimal subcarrier allocation to find suitable DAUs; optimal power allocation for each subcarrier. Moreover, in the dense scenario, we consider UEs could access the same channel and generate co-channel interference. The optimization problem could be transformed into a convex form based on interference upper bound and fractional programming. In addition, an energy-efficient DAU selection scheme based on the large scale fading is developed to maximize EE. Finally, simulation results demonstrate the effectiveness of the proposed algorithm for both sparse and dense scenarios.

• Proceedings of the KSME Conference
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• 2007.05b
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• pp.1986-1991
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• 2007

KEPRI has studied anode-supported planar SOFCs and kW class stacks operated at intermediate temperature for development of a combined heat and power unit. A single cell composed of Ni-YSZ/FL/ScSZ/LSCF showed the maximum power density of 0.55 W/$cm^2$ at $650^{\circ}C$ and 1.8 W/$cm^2$ at $750^{\circ}C$. With 37 cells of 10${\times}10cm^2$ and stainless steel interconnects, a 1kW class SOFC stack was manufactured. When a 1kW class SOFC system was operated at $750^{\circ}C$ with city gas, it showed the power output of 1.3 kWe at 50 A. It also recuperated heat of 0.57-1.2 kWth according to the loaded current through combustion of unreacted anode off-gas. Recently, KEPRI is developing a new kW class SOFC stack and system to increase efficiency and durability at intermediate temperature.

• 한국생물공학회:학술대회논문집
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• 2003.04a
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• pp.289-292
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• 2003

Effects of immobilization on the production of human granulocyte-macrophage colony-stimulating factor (hGM-CSF) by Nicotiana tabacum cells were investigated using alginate and polyurethane foam as immobilization matrices. Encapsulation of the cells in alginate decreased protein production by 50% compared with that of suspension culture. Maximum hGM-CSF concentration was obtained by the cells immobilizaed in polyurethane foam. High hGM-CSF production could be possible when polyurethane foam was used because of high specific production and easy immobilization for cell recycling process with high cell density.

• Journal of the Korean Vacuum Society
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• v.22 no.3
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• pp.162-167
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• 2013

An epitaxial layer structure for heterojunction p-InGaP/N-InAlGaP solar cell has proposed. Simulation for current density-voltage characteristics has been performed on p-InGaP/N-InAlGaP structure and the simulation results were compared with p-InGaP/p-GaAs/N-InAlGaP structure and homogeneous InGaP pn junction structure. The simulation result showed that the maximum output power and fill factor have greatly increased by replacing n-InGaP with N-InAlGaP. The thicknesses of p-InGaP and n-InAlGaP were optimized for the epitaxial layer structure of p-InGaP/N-InAlGaP.

• Ocean and Polar Research
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• v.34 no.1
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• pp.65-71
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• 2012

Gambierdiscus toxicus, Adachi et. Fukuyo, is a benthic ciguatoxin-producing armored dinoflagellate, often attached to macroalgae. This organism is the primary causative agent of ciguatera fish poisoning which occurs in tropical and subtropical regions. However, regardless of the fact that the population of Gambierdiscus spp. has expanded to such temperate areas from sub-trophic and trophic areas, monitoring of G. toxicus has been lacking in the Korean coastal waters of temperate areas. This study was performed at the uninhabited Baekdo Islands off the southern coast of Korea and at Seopsom Island in the vicinity of Seogwipo, Jeju Province during April and May, 2011. Cell densities of Gambierdiscus spp. on macroalgae at Baekdo and Jeju Island ranged from zero to 56.4 cells $g^{-1}$. Maximum density was recorded on the brown alga Cladophora japonica at St. 3 of Jeju Island. In particular, the cell densities of Gambierdiscus spp. were influenced by the substrate characteristics of macroalgae. In the future, the continuous monitoring of toxic benthic dinoflagellate is necessary to predict and prevent ciguatera poisoning in Korean coastal waters.

• The Korean Journal of Food And Nutrition
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• v.6 no.3
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• pp.178-188
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• 1993

This research was attempted to investigate changes in physicochemical properties of rice extrudate with added ginger powder extruded by single screw extruder. Graphic three dimensional analysis on response surface regression was used to evaluate effects of extrusion variables on quality factors of the extrudate according to two independent variables, ginger consent 0∼12%, moisture content 14∼26%. The summarized results are as follows : 1) Regarding proximate composition of rice extrudate with added ginger powder, as ginger powder content of raw material Increased, crude tat, crude protein, crude ash and crude fiber increased, while soluble nitrogen free extract decreased. 2) Graphic three dimensional analysis on response surface regression was conducted for each dependent variable which revealed statistically significant relationship with independent variables, 0∼120A ginger and 14∼26% moisture content. Expansion ratio had a critical point as moisture content changed. As ginger and moisture content Increased, bulk density, break strength and water absorption Index Increased, while water solubility Index decreased. The predicted maximum degree of gelatinization in 6.15% ginger and 15.56% moisture content is 88.27%, and lightness decreased as ginger content Increased. According to the microstructure for the cross section of extrudate obsorbed with image analyzer, air cell number and perimeter revealed saddle point, meanwhile total area and fractarea of air cell had critical points as moisture content changed. In view of the results, quality of rice extrudate with added ginger powder was optimum when rice flour was fed to the extruder with 2∼7% singer powder and 15∼20% moisture content.