• 한국해양학회지
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• v.17 no.2
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• pp.74-82
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• 1982

The study on the variation coefficient of water temperature and salinity was comducted during the year from 1968 to 1980 in the Southern Sea of Korea. The results obtaland from the study as followes; 1. The variation coefficient of water temperature and salinity wewe large either at the front area or the thermocline and malocline area. 2. The variation coefficient of water temperature was the largest at the time when the power was strong ty each water mass(The largest value in Tsushima and Yellow Sea Warm Current area was occurred at the 50m layer in the Summer, and that in the South Korean Coastal Water area and the Southern Part of Yellow Sea was at all layer in the Winter). 3. The variation coefficient of salinity was the largest at the surface layer in warm current area that was influenced by the low salinity of the East China Coastal Water in the Summer ,and that of salinity in the South Korean Coastal Water area and Soutern Part of Yellow Sea was nearly half of the value of the warm current area.

• Solar Energy
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• v.8 no.2
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• pp.46-56
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• 1988

This investigation concerns thermal stratification of the water due to the temperature difference (${\Delta}T=T_{\infty}-T_i$) between the mean temperature of the water in the test tank (1m wide, 1m high, 2.1m long) and the temperature of the inflow water into the tank; flow rate of circulating water and height of the sink diffuser in the test tank. The additional objectives was to observe a stratification phenomena near an interface by measuring the velosities and the temperature difference and investigate an availabilities of the better effective hot water through establishing thermocline near an interface around the bottom of the tank. Following results were obtained through the experiments. 1. When the flow rate was constant and the temperature difference (${\Delta}T=T_{\infty}-T_i$) between the mean temperature of the flow in the test tank and the temperature of the inflow water increased by 5.6, 9.5, 13.5($^{\circ}C$), obtained the better effective advantage of hot water and the stress near an interface increased gradually. 2. When the ${\Delta}T=T_{\infty}-T_i$ was constant and flow rate increased by 4.0, 4.8, 6.4, 8.0 (LPM), obtained the better effective advent age of hot water and the mean stress near an interface increased gradually. 3. When the height of the sink diffuser was 25cm from tank bottom in comparison with 50cm, obtained the better effective advantage of hot water and the mean stress near an interface increased.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.9 no.1
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• pp.43-54
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• 1997

This paper presents an approximate analytical solution to a two-region one-dimensional model for the charging process of stratified thermal storage tanks with variable inlet temperature in the presence of momentum-induced mixing. Based on the superposition principle, an arbitrary-varying inlet temperature is decomposed into inherent discontinuous steps and continuous intervals approximated as a finite number of piecewise linear functions. This approximation allows the temperature of the upper perfectly-mixed layer to be expressed in terms of constant, linear and exponential functions with respect to time. Applying the Laplace transform technique to the model equation for the lower thermocline layer subject to each of three representative interfacial conditions yields compact-form solutions, a linear combination of which constitutes the final temperature profile. A systematic method for deriving solutions to the plug-flow problem having polynomial-type boundary conditions is also established. The effect of adiabatic exit boundary on solution behaviors proves to be negligible under the actual working conditions, which justifies the assumption of semi-infinite domain introduced in the solution procedure. Finally, the approximate solution is validated by comparing it with an exact solution obtained for a specific variation of inlet temperature. Excellent agreements between them suffice to show the necessity and utility of this work.

• Journal of the Korea Institute of Military Science and Technology
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• v.13 no.6
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• pp.1034-1042
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• 2010

This study investigates effects of three different parameterizations of vertical mixing scheme on upper ocean simulation of the East Sea, focusing on the seasonal variations of the sea surface temperature(SST) and the mixed layer depth(MLD) using an ocean general circulation model(GFDL MOM1.1). The considered vertical mixing schemes are the Laplacian scheme(L scheme) that use a constant eddy coefficient, the Mellor-Yamada scheme(MY scheme), and a new scheme(Noh scheme). The Noh scheme, a second-order turbulence closure, was developed considering recent observational evidences such as the enhancement of turbulent kinetic energy near the sea surface. During summer L scheme underestimates the SST, while MY scheme overestimates the SST, compared to climatological SST. Noh scheme produces the SST in better agreement with climatological one. During winter all schemes overestimate the SST up to $4^{\circ}C$ compared to climatological SST. Vertical profiles of the basin-mean temperature show that L scheme produces higher temperature below the thermocline than those of other schemes. The winter MLD simulated from L scheme is rather large compared to that from other schemes, but the differences in MLD during summer are not significant.

• Solar Energy
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• v.19 no.4
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• pp.33-43
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• 1999

The study on ice thermal storage system is to improve total system performance and increase the economical efficiency in actual all-conditioning facilities. To obtain the high charging and discharging efficiencies in ice thermal storage system, the improvement of thermal stratification is essential, therefore the process flow must be piston flow in the cylindrical type. With the relation of the aspect ratio(H/D) in the storage tank, the stratification is formed better as inlet flow rate is smaller. If the inlet and the outlet port are settled at the upside and downside of the storage tank, higher storage rate could be obtainable. In case that the flow directions inside the thermal storage tank are the upward flow in charging and the downward in discharging, thermal stratification is improved because the thermocline thickness is maitained thin and the degree of stratification increases respectively. In the charging process, in case of inlet flow rate the thermal stratification has a tendency to be improved with the lower flow rate and smaller temperature gradient in case of inlet temperature, the large temperature difference between inflowing water and storage water are influenced from the thermal conduction. The effect of the reference temperature difference is seen differently in comparison with the former study for chilled and hot water. In the discharging process, the thermal stratification is improved by the effect of the thermal stratification of the charging process.

• Nuclear Engineering and Technology
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• v.56 no.3
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• pp.1052-1065
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• 2024

Advanced Pressurized Water Reactors (APWRs) and Boiling Water Reactors (BWRs) employ a suppression pool as a heat sink to prevent containment overpressure. Steam can be discharged into the pool through multi-hole spargers or blowdown pipes in both normal and accident conditions. Direct Contact Condensation (DCC) creates sources of momentum and heat. The competition between these two sources determines the development of thermal stratification or mixing of the pool. Thermal stratification is of safety concern as it reduces the cooling capability compared to a completely mixed pool condition. In this work we develop a scaling approach to prediction of the thermal stratification in a water pool induced by steam injection through spargers. Experimental data obtained from large-scale pool tests conducted in the PPOOLEX and PANDA facilities, as well as simulation results obtained using validated codes are used to develop the scaling. Two injection orientations, namely radial injection through multi-hole Sparger Head (SH) and vertical injection through Load Reduction Ring (LRR), are considered. We show that the erosion rate of the cold layer can be estimated using the Richardson number. In this work, scaling laws are proposed to estimate both the (i) transient erosion velocity and (ii) the stable position of the thermocline. These scaling laws are then implemented into a 1D model to simulate the thermal behavior of the pool during steam injection through the sparger.

• Journal of the korean society of oceanography
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• v.34 no.2
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• pp.95-112
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• 1999

To investigate a phytoplankton community structure and its biomass distribution in the Korea Strait, phytoplankton pigments were quantitatively measured by HPLC method, with hydro-graphic conditions in August and October, 1996. The measured chi. a concentrations were in the range of 7.1-1,280.7 ng/1. Horizontal distribution pattern of chi. a in summer (August) was very different from that of autumn (October). High concentration of chi. a occurred near the coast with relatively low salinity (< 33%). Vertically, the highest concentrations of pigments at most of the stations were found near the surface and above the thermocline. The maximum concentration of chi. a in October was four times higher than in August. It was notable to measure relatively high concentration of chi. b up to 190.8 ng/1 in the study area, since chi. bcontaining green algae and prochlophytes have been ignored because of their minute size and sensitivity to common preservatives. Major carotenoids detected were fucoxanthin, zeaxanthin, 19'-hexanoyloxyfucoxanthin, and prasinoxanthin. Diatoms were the dominant group with secondary important groups as pryrnnesiophytes and cyanobacteria for the biomass of phytoplankton for both cruises. The dominant species of diatoms in summer were Thalassiosira sp. and Chaetoceros peruvianus. As minor groups, prasinophytes, crysophytes, and cryptophytes were confirmed by their marker pigments and dinoflgellates by microscopical observation. Degradation products of chi. a was minor. Interestingly, at 200 m depth of St A4, the deepest station in the western channel of the Korea Strait, substantial amounts of chi. a including fucoxanthin, 19'-hexanoyloxyfucoxanthin, chi. b, and degradation products of chi. a was measured from both cruises. Higher concentration (2-3 times) of those pigments were detected from samples in summer than in autumn. Small decrease in concentration of phosphate at this depth of St. A4 was also observed. It suggested that this bottom cold water was transported from the subsurface water with biomass of active phytoplankton, which was sunk and flowed southward.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.29 no.1
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• pp.1-10
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• 1993

In order to investigate the environmental properties of set net grounds located in the coastal waters of Yeosu, oceanographic observations on the fishing grounds were carried out by the training ship of Yeosu Fisheries University from Jun. 1988 to Dec. 1990. The resultes obtained are summarized as follows; 1) The water mass in the fishing grounds were divided into the inner water (29.50-31.00$\textperthousand$), the mixed water (31.10-32.70$\textperthousand$) and the offshore water (32.70-34.30$\textperthousand$) according to the distribution of salinity from T-S diagram plotted all salinity data observed from Jun. 1988 to Dec. 1990. In spring the mixing water prevailed and in summer the inner and mixing water. But in autumn and winter the mixing and offshore waters prevailed. 2) The inner water which was formed by land water from the river of Somjin and the precipitation in the Yeosu district flowed southerly along the coast of Dolsando and spread south-easterly in the vicinity of Kumodo. The inner water and offshore water which supplied from the vicinity of Sorido and Yokchido formed the thermal front and halofront. 3) As the mixing water flowing from the western sea of Cheju to the southern coast of korea was low in temperature, the water mass of low temperature which appeared at the offshore bottom of Sorido in summer was considered not to be the Tsushima warm current. 4) As vertical mixing was made frequently in spring, autumn and winter, the differences in temperature and salinity between surface and bottom was respectively small. In summer, however, the mixing was not made because of the inner water expanded offshore through the space between surface and 10m layer and so a thermocline of $2.0^{\circ}C$/10m and halocline of 4.0$\textperthousand$/10m respectively in vertical gradient was formed. 5) In the vicinity of Dolsando and Kum a water low in salinity prevailed, but in the vicinity of Namhaedo and YoKchido the reverse took place. The inner and mixing waters formed at these arease was limited to the observation area not to spread widely.

• Journal of the Korean earth science society
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• v.28 no.3
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• pp.343-356
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• 2007

This paper explored the characteristics of the interannual sea surface temperature (SST) variability in the equatorial Pacific by analyzing the simulated data from a newly coupled general circulation model (CGCM). The CGCM simulates well the realistic ENSO variability as well as the mean climatologies including SST, seasonal cycle, precipitation, and subsurface structures. It is argued that the zonal gradient of SST in the equatorial Pacific is responsible for the over-energetic SST variability near the equatorial western boundary in the model. This variability could also be related to the strong westward propagation of SST anomalies which resulted from the enhanced the zonal advection feedback. The simple two-strip model supports this by sensitivity tests. Analysis of the relationship between zonal mean thermocline depth and NINO3 SST index suggested that the ENSO variability is controlled by the recharge-discharge oscillator of the model. The lead-lag regression result reveals that heat buildup process in the western equatorial Pacific associated with the increase of the barrier layer thickness (BLT) is a precedent condition for El $Ni\widetilde{n}o$ to develop.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.50 no.4
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• pp.476-486
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• 2014

This study is aimed to understand the vertical distribution of fish in the daytime and nighttime using an acoustic survey in Yondam reservoir of Jeollabuk-do, and an acoustical backscattering strength of dominant species, bass (Micropterus salmoides) and a bluegill (Lepomis macrochirus), which are classified as the ecosystem disturbing species. The results showed that the fish school was distributed in the shallow areas of less than 10 m depth during the period of Aug. and Oct. where it had a strong thermocline, otherwise, it was distributed over 10-times density under stable water temperatures as $13^{\circ}C$ in Nov. There was no vertical patchiness difference between daytime and nighttime unlike the typical marine ecosystem. The dominant species were crucian carp, bluegill, bass. The hydroacoustic method can provide the spatial distribution and effective removal ways of the ecosystem disturbing species in inland fisheries.