• 한국환경과학회지
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• 제13권5호
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• pp.469-478
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• 2004

Atmospheric bulk (wet and dry) samples were monthly collected in an urban environment (Daeyeon-dong) of Busan over a year, to assess the deposition flux and seasonality of dioxin-like polychlorinated biphenyls (DLPCBs) using stainless steel pots. Deposition fluxes of DLPCBs in bulk samples were determined using high resolution gas chromatography coupled to high resolution mass spectrometry (HRGC/HRMS). Particle deposition fluxes in the urban environment varied from 23 to 98 $mg^2$/year (mean 41 $gm^2$/year). DLPCB deposition fluxes in atmospheric bulk samples ranged from 0.09 to 0.77 ng-$TEQ/m^2$/year (mean 0.35 ng-$TEQ/m^2$/year). Seasonal atmospheric deposition fluxes of DLPCBs were high in winter and low in summer. Atmospheric deposition fluxes of particles and DLPCBs in this study were comparable to or slightly lower values than those of different locations in the world. Monthly DLPCB profiles in deposition bulk samples were similar over a year. Non-ortho PCBs were higher contributions to the total DLPCBs fluxes than mono-ortho PCBs. In particular, PCB 126 had the highest concentrartion (>75%) in all deposition samples, followed by PCB 169 and PCB 156. A highly positive correlation was found among the deposition fluxes of DLPCB species, suggesting the possibility of that the DLPCB contamination originated from one source. The deposition fluxes of DLPCBs were not significantly correlated with temperature and the amount of precipitation even though the summer season with the highest temperature and the largest amount of precipitation showed the lowest DLPCB deposition flux.

• Ocean Science Journal
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• 제43권2호
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• pp.115-126
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• 2008

Direct measurements of four radiative components at air-sea boundary layer were conducted in the southern Yellow Sea during three cruises (seasons) in 2007. Simultaneous observations of meteorological (cloud cover, air temperature and humidity) and oceanographic (sea surface temperature) parameters were carried out. Observational results of radiative fluxes and meteorological and oceanographic parameters are presented. Mean diurnal cycles of four radiative components, net radiation, and sea surface albedo are calculated to achieve averages in different seasons. Net radiative fluxes in three seasons (winter, spring, autumn) are 8, 146, $60\;W/m^2$, respectively. Comparisons between the observed radiative fluxes and those estimated with formulas are taken.

• Ocean and Polar Research
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• 제21권2호
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• pp.149-157
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• 1999

Surface sediment samples collected from the eastern half of the Yellow Sea proper in 1998 were analyzed for polycyclic aromatic hydrocarbons (PAHs), ubiquitous pollutants. Total PAHs concentrations varied from 1.0 to $320.5ng\;g^{-1}$ dw. Relatively high concentrations of PAHs were found in the muddy central part of the Yellow Sea. Sedimentary total PAHs concentrations in the Yellow Sea proper were similar to those of Californian offshores and the central Mediterranean Sea, albeit an order of magnitude lower than the Yellow Sea nearshore areas. Phenanthene/Anthracene concentration ratio of PAHs in bottom sediments suggested that pyrolytic PAHs might be dominant over petrogenic ones in the eastern Yellow Sea. Downcore depth distributions of PAHs from the relatively undisturbed core samples of the central Yellow Sea showed decreasing PAHs concentrations with core depths and suggested that the Yellow Sea has been increasingly exposed to PAH for decades. Annual total PAH flux to these sediments was estimated to be $166{\mu}gm^{-2}yr^{-1}$ in the central part of the Yellow Sea for the recent decade.

• 한국환경과학회지
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• 제15권2호
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• pp.121-131
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• 2006

Atmospheric bulk (wet and dry) samples were monthly collected in Masan and Heangam areas of Korea, to assess the deposition flux and seasonal variation of polycyclic aromatic hydrocarbons (PAHs). Deposition fluxes of PAHs in bulk samples were determined using gas chromatography coupled to mass spectrometer detector (GC/MSD). Particle deposition fluxes from Masan and Haengam areas varied from 13 to $87\;g/m^2/year$ and from 5 to $52\;g/m^2/year$, respectively. PAHs deposition fluxes in atmospheric bulk samples in Masan and Haengam areas ranged from 135 to $464\;{\mu}g/m^2/year$ and from 62.2 to $194\;{\mu}g/m^2/year$, respectively. Atmospheric deposition fluxes of particles and PAHs in this study were comparable to or slightly lower values than those from different locations in Korea and other countries. PAHs profiles of atmospheric deposition bulk samples showed slightly different from two sampling areas, however the predominant species of PAHs were similar. Indeno (1,2,3-c,d)pyrene, benzo(g,h,i)perylene, phenanthrene compounds were the most detected PAHs in deposition bulk samples. Carcinogenic PAHs occupied the contribution of approximately $30-40\%$ of the total PAHs deposition fluxes. The non-metric multi-dimensional scaling (MDS) was used, to assess the differentiation of PAHs source between two sampling areas. The result suggests that PAHs contamination sources were different according to the location and season surveyed. There was no an apparent relationship between the PAHs deposition flux against temperature and rainfall amount, even though summer season with the highest temperature and the largest amount of precipitation showed the lowest PAHs deposition flux. Benzo(e)pyrene/benzo(a)pyrene ratio indicated that the photo-degradation process was one of important factors to the seasonal variation of PAHs with the lower deposition fluxes.

• Ocean and Polar Research
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• 제33권spc3호
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• pp.385-395
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• 2011

Time-series sediment traps were deployed at 1,000 m water depth of the northwestern subtropical Pacific from July 2009 to June 2010, with the aim of understanding temporal and spatial variations of sinking-particle fluxes. The opening and closing of the traps was synchronized at 18-day periods for 20 events. Total mass fluxes showed distinct seasonal variations with high values for the summer-fall seasons and relatively low values for winter-spring. This seasonal variation at two stations was characterized by a distinct difference in $CaCO_3$ fluxes between the two seasons. The enhanced $CaCO_3$ flux in the summer - fall seasons might be attributed to an increased planktonic foraminiferal flux. Total mass flux at FM10 station was nearly 50% higher than that at FM1 station. The difference in $CaCO_3$ fluxes between two stations contributed nearly 70% of the difference of total mass fluxes. The $CaCO_3$ flux was a major component controlling temporal and spatial variation of sinking - particle fluxes in the western subtropical Pacific Ocean.

• Journal of Advanced Marine Engineering and Technology
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• 제27권5호
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• pp.624-632
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• 2003

In the gasoline engine industry. there has been a trend towards the development of high performance engines with improved fuel efficiency, reduced weight and smaller sizes. These trends help to solved engine problems related to thermal load and abnormal combustion. In order to investigate these Problems, a thin film-type probe for instantaneously measuring temperatures has been suggested. A method for manufacturing such a probe was established in this study. The instantaneous surface temperature of a constant volume combustion chamber was measured by this probe and the heat flux was obtained through Fourier analysis. A peak instantaneous temperature was obtained after 55∼60 ms from ignition and the temperature increased according to an equivalence ratio and varied differently according to the position of the probe. Total heat loss during combustion period was affected by the equivalence ratio and differed widely in accordance to the position of the probe.

• 한국마린엔지니어링학회:학술대회논문집
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• 한국마린엔지니어링학회 2002년도 춘계학술대회논문집
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• pp.41-47
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• 2002

A model of simultaneous heat and mass transfer process in absorption of refrigerant vapor into a lithium bromide solution of water-cooled vertical plate absorber was developed. The model can predict temperature and concentration profiles as well as the absorption heat and mass fluxes, the total heat and mass transfer rates and the heat and mass transfer coefficients. Besides, the effect of operating condition on absorption mass flux has been investigated, with the result that the absorption mass flux is increased as the inlet cooling water temperature decreases, the system pressure increases and the inlet solution concentration increases. And among the effects of operating parameters on absorption mass flux, the effect of inlet solution concentration is dominant.

• Journal of Advanced Marine Engineering and Technology
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• 제24권6호
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• pp.102-109
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• 2000

In this industrial induction motor speed and torque controlled drive system, the closed loop control usually requires the measurement of speed or position of amotor. However a sensorless drive of an induction motor has several advantages ; low cost and mechanical simplicity. Thus this paper investigates a field oriented control method without speed and flux sensors. The proposed control strategy is based on the Model Reference Adaptive System(MRAS) using a new flux estimator which replaces integrators with two lag circuits as the reference model. This algorithm may overcome several shortages of conventional MRAS such as integrator problems, small EMF at low speed. The simulation and experimental results indicate good speed responses.

• 한국마린엔지니어링학회:학술대회논문집
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• 한국마린엔지니어링학회 2001년도 추계학술대회 논문집(Proceeding of the KOSME 2001 Autumn Annual Meeting)
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• pp.8-14
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• 2001

The purpose of this study is to elucidate heat characteristics according to inclination angle of the hot flat plate at the spray cooling. As results of this experiment, the heat flux, the heat transfer coefficient and the cooling speed are increased as the liquid volume flux and subcooled temperature go up. And as the inclination angle of the heat transfer surface is increased, the cooling speed on the inclined flat plate becomes faster. It means that the cooling ability is increased because droplets were excluded by gravity.

• 수산해양교육연구
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• 제26권3호
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• pp.639-646
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• 2014

A heat exchanger using two-phase loop thermosyphons was developed as a waste heat recovery system. An experimental study was carried out on the heat transfer characteristics of two-phase loop thermosyphons heat exchanger and the results from the experiments were used to see the possibility which the two-phase loop thermosyphons could be an alternate solution for waste heat recovery system. In the present work, R134a has been used as the working fluid and the filling rate do working fluid and heat flux have been used as the experimental parameters. The results show that the filling rate of working fluid and heat flux are very important factors for the operation of two-phase loop thermosyphons. The experimental results showed the provisional results as a waste heat recovery system.