• Journal of Marine Bioscience and Biotechnology
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• v.6 no.2
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• pp.68-75
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• 2014

This study investigated the potential use of various organic carbon sources (glucose, glycerol and acetate) and different concentrations of $CO_2$ for culturing marine microalga Dunaliella tertiolecta. Cell growth and lipid production were monitored under heterotrophic, mixotrophic and photoautotrophic modes of cultivation. D. tertiolecta showed the ability to grow under mixotrophic (acetate and glucose), heterotrophic (glucose) and photoautotrophic condition under high $CO_2$ concentration (15%). With all the organic carbon sources (glucose, glycerol and acetate) tested in this study, 1~5% acetate enhanced cell growth rate and lipid content, while higher concentrations of acetate (10% and 15%) were inhibitory and resulted in cell death.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.104.2-104.2
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• 2013

A residual gas analyzer (RGA) system has been developed in this laboratory. Characteristics of the RGA system parts such as ion source, quadrupole mass filter and sensitivity are introduced. Some efforts have been made to improve performance of the two types of ion sources, open ion source (OIS) and closed ion source (CIS). A metal mesh was placed onto the electron beam entrance of the CIS anode tube to block the filament field penetration. Sensitivity of the CIS ion sources with and without the mesh was compared by mass spectra of SF6 gas (97% He base) introduced into the CIS anode through a needle valve. About ten-times improvement in the RGA sensitivity was observed for the CIS with the mesh in the electron entrance. Computer simulation showed an axi-symmetric anode potential distribution and improved focusing of the electron beam inside the anode tube with the mesh.

• Korean Chemical Engineering Research
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• v.56 no.6
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• pp.841-855
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• 2018

The purpose of this study is to estimate the available potential heat source for heat pump in the district heating supply area in the city. Unused energy potentials were estimated and integrated based on open source based data. In particular, geographical spatial analysis of recoverable heat energy density and heat demand in the heat source area of large retailers and public sauna facilities in the DH network located in the southern part of the metropolitan area (Pyeongtaek-si) was conducted. As a result of the study, the DH network area had a total potential energy of 1,741.7 toe/year for the two heat sources of large retailers and public saunas. It is estimated that 1,006.9 toe/year, which is 57.8% of the total, can be linked to the district heating. The large retailers showed a positive correlation with the floor area and energy use of 0.4937. The recoverable energy intensity was estimated to be $0.0017toe/m^2$ per unit area and $0.0069tCO_2/m^2$ for greenhouse gas emissions. In addition, public saunas were analyzed by comparing the empirical case with the theoretical calculation, and it was estimated that energy conservation estimate of 80% was $0.0315toe/m^2$ per bath area and $0.1183tCO_2/m^2$ for greenhouse gas emissions. The total potential energy amount of this area was positively correlated with the heat demand of apartment house by administrative district, and it was confirmed that it had a relatively high potential energy especially in traffic and commercial center.

• Journal of Biomedical Engineering Research
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• v.15 no.1
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• pp.105-110
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• 1994

In this paper, we present a method to evaluate source locations and distributed region which is specified brain activity, as indicated by locations and strengths of intracranial sources, using potential gradients of interpolation polynomials and topographic mapping of the EEG records. This method can analyze the variance of source temporally or spatially and leads to enable a quantitative evaluation of potential gradients drawing methods which is now being used in the clinic. In the result, we obtained the overall potentials distribution on the entire scalp and the information of potential source locations from the EEG records of a patient which was known to epilepsy.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1996.11a
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• pp.743-747
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• 1996

A Potential Field Method is applied to the proposed algorithm for the planning of collision-free paths of redundant manipulators. The planning is carried out on the base of kinematic configuration. To make repulsive potentials, sources are distributed on the boundaries of obstacles. To escape from local minimum of the main potential and to attack other difficulties of the planning, various potentials are defined simultaneously, Inverse Kinematics Problems of the redundant manipulators are solved by unconstrained optimization method. Computer simulation result of the path planning is presented.

• The Bulletin of The Korean Astronomical Society
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• v.41 no.2
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• pp.47.1-47.1
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• 2016

We present a preliminary result of search for CO molecular outflows toward a sample of 68 candidate Very Low Luminosity Objects (VeLLOs; Lint ${\leq}0.1L_{\odot}$) to help to understand their physical properties. The sources have been identified using the data at IR to radio wavelengths by M. Kim et al. 2016 toward nearby star-forming regions in the Gould belt. These sources were observed in rotational transitions 2-1 and 3-2 of $^{12}CO$, $^{13}CO$, and $C^{18}O$ molecules with SRAO, CSO, JCMT, and ASTE telescopes. In the beginning of our survey we made a single pointing observation in $^{12}CO$ 2-1 or 3-2 lines for our sample, identifying 53 sources as potential outflow candidates from their line wing features. We made full or partial mapping observations for these candidates with the same lines, finding 33 sources with bipolar or one-sided outflow features. Out of these 33 sources, 6 VeLLOs are previously known sources to have their outflows and 27 VeLLOs are found to be new outflow sources identified from this study. We estimated outflow properties with corrections for excitation temperature, optical depth, and inclination. Their outflow forces range from $8.7{\times}10^{-10}$ to $6.0{\times}10^{-5}M_{\odot}\;km\;s^{-1}yr^{-1}$ with a median value of $3.6{\times}10^{-7}M_{\odot}\;km\;s^{-1}yr^{-1}$, indicating that most of the VeLLOs are less powerful than those for protostars. Their accretion luminosities vary from $9.7{\times}10^{-9}$ to $166L_{\odot}$ with a median value of $0.004L_{\odot}$, implying that most VeLLOs have larger ratios of the accretion luminosity to the internal luminosity but a significant number of VeLLOs have smaller ratios. This result suggests that many of the VeLLOs can be explained with episodic accretion but a significant number of VeLLOs cannot.

• Journal of Korean Society on Water Environment
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• v.38 no.2
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• pp.63-71
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• 2022

This study aimed to maximize the potential of fluorescence 3D excitation-emission matrix (EEM) for predicting the trihalomethane formation potential (THMFP) of DOM with various sources. Fluorescence spectroscopy is a useful tool for characterizing dissolved organic matter (DOM). In this study, differential spectroscopy was applied to EEM for the prediction of THMFP, in which the difference between the EEM before and after chlorination was taken into account to obtain the differential EEM (DEEM). For characterization of the original EEM or the DEEM, the maximum intensities of several different fluorescence regions in EEM, fluorescence EEM regional integration (FRI), and humification index (HIX) were calculated and used for the surrogates for THMFP prediction. After chlorination, the fluorescence intensity decreased by 77% to 93%. In leaf-derived and effluent DOM, there was a significant decrease in the protein-like peak, while a more pronounced decrease was observed in the humic-like peak of river DOM. In general, leaf-derived and effluent DOM exhibited a relatively lower THMFP than the river DOM. Our results were consistent with the high correlations between humic-like fluorescence and THMFP previously reported. In this study, HIX (r= 0.815, p<0.001), FRI region V (r=0.727, p<0.001), humic-like peak (r= 0.827, p<0.001) from DEEM presented very high correlations with THMF P. When the humic-like peak intensity was converted to a logarithmic scale, a higher correlation was obtained (r= 0.928, p<0.001). This finding suggests that the humic-like peak in DEEM can serve as a universal predictor for THM formation of DOM with various origins.

• Korean Journal of Environmental Biology
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• v.27 no.3
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• pp.279-284
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• 2009

In order to understand food sources-metabolism for the pacific oyster (Crassostrea gigas), the stable isotope ratios of carbon (${\delta}^{13}C$) and nitrogen (${\delta}^{15}N$) of its gut, gill, and muscle as well as potential food sources (particulate organic matter, sedimentary organic matter, benthic microalgae, seagrass detritus) were determined in Dongdae Bay. Average ${\delta}^{13}C$ and ${\delta}^{15}N$ values reflect that oysters primarily fed on sedimentary organic matter as opposed to suspended organic matter during summer and winter seasons. However, the relatively enriched $^{15}N$ values of particulate organic matter (>$250{\mu}m$) and sedimentary organic matter in the summer may be due to the photosynthetic incorporation of $^{15}N$-enriched nitrogen (DIN) or the spawning events of bivalves. Specific oyster tissues (gut, gill, and muscle) revealed different metabolic pathways, which were determined through analysis of ${\delta}^{13}C$ and ${\delta}^{15}N$ in each organ. The present results suggest the determination of carbon and nitrogen stable isotopes to be a useful approach in ecological research related to the food sources- metabolism of Crassostrea gigas.

• Magazine of the Korean Society of Agricultural Engineers
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• v.39 no.2
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• pp.9-18
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• 1997

Abstract This paper presents a heuristic method for optimal design of water distribution system with multiple sources and potential links. In multiple source pipe network, supply rate at each source node affects the total cost of the system because supply rates are not uniquely determined. The Linear Minimum Cost Flow (LMCF) model may be used to a large scale pipe network with multiple sources to determine supply rate at each source node. In this study the heuristic method based on the LMCF is suggested to determine supply rate at each source node and then to optimize the given layout. The heuristic method in turn perturbs links in the longest path of the network to obtain the supply rates which make the optimal design of the pipe network. Once the best tree network is obtained, the frequency count of reconnecting links by considering link failure is in turn applied to form loop to enhance the reliability of the best tree network. A sample pipe network is employed to test the proposed method. The results show that the proposed method can yield a lower cost design than the LMCF alone and that the proposed method can be efficiently used to design irrigation systems or rural water distribution systems.

• Environmental and Resource Economics Review
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• v.15 no.2
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• pp.269-296
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• 2006

With the concern of the potential problems which can be observed in terms of the power supply of renewable energies, we need to analyze the impact of additional power generation capacities of renewable energy sources on peak load. Each renewable energy sources are dependent upon wind speed, solar radiation, head differences caused by lunar calendar. Considering that these exogenous renewable energy sources follow their own stochastic distributions, we analyze the probability distribution of the impact of each renewable energy power supply on peak load. As a conclusion, we note that traditional tools used for the analysis of power supply such as capacity factors are no longer appropriate for the analysis of renewable energy sources in that perspective.