• Ocean and Polar Research
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• v.26 no.3
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• pp.453-463
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• 2004

The Antarctic Peninsula is important in terms of global warming research due to pronounced increase of air temperature over the last century. The first eddy covariance system was established at King Sejong Station located in the northern region of the Antarctic Peninsula in December of 2002 and has been operated over one year. Here, we analyze turbulent characteristics to determine quality control criteria for turbulent sensible heat flux data as well as to diagnose the possibility of long term eddy covariance measurement under extreme weather conditions of the Antarctic Peninsula. We also report the preliminary result on sensible heat flux. Based on the analyses on turbulent characteristics such as integral turbulence characteristics of vertical velocity (w) and heat (T), stationarity test and investigation of correlation coefficient, they fallow the Monin-Obukhov similarity and eddy covariance flux data were reliable. ${\sim}47%$ of total retrieved sensible heat flux data could be used for further analysis. Daytime averaged sensible heat flux showed a pronounced seasonal variation, with a maximum of up to $300Wm^{-2}$ in summer. In conclusion, continuous and long-term eddy covariance measurement may be possible at the study site and the land surface may influence the atmosphere significantly through heat transport in summer.

• Proceedings of KOSOMES biannual meeting
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• 2007.11a
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• pp.187-188
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• 2007

The fluctuations of biochemical and molecular activities III the harmful dinoflagellate, Cochlodinium polykrikoides, depending on water temperatures, were studied. In genomic DNA concentration, a similar value of 0.6 was shown at $12^{\circ}C$ and $15^{\circ}C$, but significantly increasing DNA from $18^{\circ}C$ (p<0.05), with a maximum of 1.8 at $24^{\circ}C$. After$24^{\circ}C$, the DNA significantly decreased to 0.6. Likely, the concentrations of RNA and total protein were at their highest values of 1.7 and 0.07 g $mL^1$ at $24^{\circ}C$, respectively. In contrast to ONA, RNA and total protein began to increase at $15^{\circ}C$. Oxygen availability between lower and higher temperatures was significantly different and increased from $18^{\circ}C$ according to light intensity, regardless of wavelengths (p<0.05). At $24^{\circ}C$, the highest value of the maximum electron transport rate (ETRmax), ranging from 537.9 (Ch 1) to 602.5 mol electrons $g^{-1}$ Ch1 a $s^{-1}$ (Ch 4), was also shown. Nitrate reductase (NR) and ATPase activities were at their highest values of 0.11 mol $NO_2^-g^{-1}$ Ch1 a $h^{-1}$ and 0.78 pmol 100 $mg^{-1}$ $at^2$ $4^{\circ}C$, respectively. When the cells cultured at $15^{\circ}C$, NR and ATPase activities significantly increased compared to $12^{\circ}C$ (p<0.05). In an analysis of CHN, the concentration of C and N also significantly increased (p<0.05). However, at $27^{\circ}C$, most of the molecular and biochemical movements were much lower, compared to $24^{\circ}C$. These results suggest that C. polykrikoides is very sensitive biochemical and molecular activities depending on water temperatures. Possibly, it is desirable to estimate at $18^{\circ}C$ the initiation of the massive blooming development of C. polykrikoides. In nature, it will be very difficult to maintain the massive blooms after $24^{\circ}C$ because of the possibility of significantly decreasing the molecular movement and activity of C. polykrikoides.

• Journal of the Korean Chemical Society
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• v.22 no.5
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• pp.304-310
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• 1978

The relative permeabilities, distribution coefficients and diffusion coefficient of some salts which are important components in blood plasma through a poly(HEMA) membrane were measured. The crosslinker which was used for preparing the membrane was tetraethylene glycol dimethacrylate(TEGDMA), the weight percentage of the latter was about 2.8. We found that the diffusion coefficients ($D_m$) of the solutes decrease exponentially with increasing molecular weight, and also that $D_m$'s decrease linearly (except urea) with cylindrical radius (a). These facts were explained by a sieve pore flow model. The relative permeability and diffusion coefficient of urea at various temperature were larger than those of other solutes such as glycine, ${\beta}$-alanine, D-glucose, saccharose and maleic acid. The result indicates that the poly(HEMA) membrane might be suitable for hemodialysis application.

• Journal of Magnetics
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• v.19 no.3
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• pp.221-226
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• 2014

Significantly enhanced low-field magnetoresistance (LFMR) and maximum dMR/dH {$(dMR/dH)_{max}$} values were successfully achieved from $La_{0.7}Sr_{0.3}MnO_3$(LSMO)-manganese oxide composite samples prepared by liquid phase sintering, compared with those of the same composites prepared by solid state reaction. For this study, pure LSMO and LSMO-manganese oxide composites with various nominal compositions of (1-x)LSMO-$xMn_2O_3$ (x = 0.1, 0.2, 0.3, 0.4, and 0.8) were sintered at $1450^{\circ}C$, above the eutectic temperature of $1430^{\circ}C$, for 1 h in air. The highest LFMR value of 1.28% with the highest $(dMR/dH)_{max}$ value of 21.1% $kOe^{-1}$ was obtained from the composite sample with x = 0.3 at 290 K in 500 Oe. This enhancement of LFMR and $(dMR/dH)_{max}$ values is ascribed to efficient suppression of magnetic disorder at the LSMO grain boundary, by forming a characteristic LSMO-manganese eutectic structure.

• Journal of the Korean Vacuum Society
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• v.12 no.S1
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• pp.95-99
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• 2003

We successfully grew InN/GaN single quantum well structures by metal-organic chemical vapor deposition and confirmed their formation by optical and structural measurements. We speculate that relatively high growth temperature ($730^{\circ}C$) of InN layer enhanced the formation of 2-dimensional quantum well structures, presumably due to high adatom mobility. As the growth interruption time increased, the PL emission efficiency from InN layer improved with peak position blue-shifted and the dislocation density decreased by one order of magnitude. The high resolution cross-sectional TEM images clearly showed that the InN layer thickness reduced from 2.5 nm (without GI) to about I urn (with 10 sec GI) and the InN/GaN interface became very flat with 10 sec GI. We suggest that decomposition and mass transport processes on InN during GI is responsible for these phenomena.

• Ocean and Polar Research
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• v.34 no.2
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• pp.197-199
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• 2012

According to the IPCC climate change scenario (A1B scenario), the surface seawater temperature of the South Sea of Korea by 2100 may be $2-3.5^{\circ}C$ higher than at present, and seawater pH may decrease from 8.1 to 7.8, due to the increase in atmospheric $CO_2$, which is predicted to increase in concentration from 380 to 750 ppm. These changes may not only intensify the strength of typhoons/storm surges but also affect the function and structure the marine ecosystem. In order to assess the impact of climate change on the marine ecosystem in Korean waters, the project named the 'Assessment of the impact of climate change on marine ecosystem in the South Sea of Korea' has been supported by the Ministry of Land, Transport and Maritime Affairs, from 2008. The goal of this project is to enhance our ability to adapt and prepare for the future environmental changes through the reliable predictions based on the knowledge obtained from projects like this. In this respect, this project is being conducted to investigate the effects of climate/marine environment changes (ocean warming and acidification), and to predict future changes of the structure and function of the ecosystem in the South Sea of Korea. This special issue contains 6 research articles, which are the highlights of the studies carried out through this project.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.26 no.12
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• pp.1646-1654
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• 2002

A two-phase closed thermosyphon was one of the most effective devices in the removing heat because of its simple structure, thermal diode characteristics, wide operating temperature range and so on. In this study, a two-phase closed thermosyphon(working fluid PFC(C6F14), container copper(inner grooved surface)) was fabricated with a reservoir which can change the fill charge ratio. The experiments were performed in the range of 50~600W heat flow rate and 10~70% fill charge ratio. The results were compared with some correlations that were presented by Rohsenow and Immura et al. in the evaporator, by Nusselt, Gross and Uehara et al. in the condenser and by Cohen and Bayley, Wallis, Kutateladze and Faghri et al. in heat transfer limitation etc.. The heat transfer coefficient at the evaporator increased with the input power. However the effect of the fill charge ratio was nearly negligible. At the condenser, it showed an opposite trend to the evaporator and with increase of the fill charge ratio, showed some enhancement of heat transfer. The heat transport limitation was occurred by the dry-out limitation for small fill charge ratio(10%) and presented about 100W. For the case of large fill charge ratio(Ψ$\geq$40%), it was occurred by the flooding limitation at about 500W.

• Journal of Advanced Marine Engineering and Technology
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• v.40 no.6
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• pp.458-467
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• 2016

Salt is the most important substance in physiological activities of the human body concerning transport of the ingested nutrients into the blood. Thus, the most ideal salt must not contain any harmful ingredients such as cadmium, mercury, lead, and arsenic. However, it is legal to include trace amounts of the hazardous ingredients in salt owing to a technical limitation, because salt is generally obtained from seawater. This paper reported an experimental result about a new method of manufacturing high-quality table salts without hazardous ingredients by using "$15^{\circ}C$ low-temperature vacuum drying technology," applied to the sequential extraction phenomenon of seawater with increasing the concentration. The world's best table salt can be produced if the present results are applied and extended to the traditional solar salt industry.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.18 no.2
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• pp.125-129
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• 2005

Two kinds of physical treatments were examined for the analysis both of intrinsic surface and interior nature of CuInS $e_2$[CIS] and CuGaS $e_2$[CGS] films grown in separated systems. For the first method, a selenium protection layer which was immediately deposited after the growth of the CIS was investigated. The Se cap layer protects CISe surface from oxidation and contamination during the transport under ambient atmosphere. The Se cap was removed by thermal annealing at temperature above 15$0^{\circ}C$. After the decapping treatment at 2$25^{\circ}C$ for 60 min, ultraviolet photoemission and inverse photoemission measurements of the CIS film showed that its valence band maximum(VBM) and conduction band minimum (CBM) are located at 0.58 eV below and 0.52 eV above the Fermi level $E_{F}$, respectively. For the second treatment, an Ar ion beam etching was exploited. The etching with ion kinetic energy $E_{k}$ above 500 eV resulted in broadening of photoemission spectra of core signals and occasional development of metallic feature around $E_{F}$. These degradations were successfully suppressed by decreasing $E_{k}$ below 400 eV. CGS films etched with the beam of $E_{k}$ = 400 eV showed a band gap of 1.7 eV where $E_{F}$ was almost centered.st centered.

• Environmental and Resource Economics Review
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• v.25 no.4
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• pp.545-564
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• 2016

Recently as fine and ultra fine particles become major environmental issues in Korea, it is very important to develop effective solutions to air pollution. Accordingly this study aims at detecting causes of air pollution by using models and examining if diesel price increases contribute to reduction of diesel consumption and air pollution. TSP, PM10, $NO_X$, $SO_X$, CO, and VOC are included as major air pollutants. As a result, we found invert U shape curve between pollution and income for all air pollutants except CO. Consumer price index, coal power capacity, diesel consumption, frequency of yellow dust, number of natural gas buses, number of transport business, annual average temperature, number of manufacturing businesses are also influential in explaining causes of air pollution. As diesel price increases by 1%, air pollutants decline between 0.07~0.12% in the short run. Simultaneously, the additional revenue from increases in diesel prices might be transferred to support expansion of biofuel market. Also, stronger policy should be developed to mitigate the current air pollution problem.