• 한국신재생에너지학회:학술대회논문집
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• 2010.11a
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• pp.121.1-121.1
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• 2010

We analyzed the temperature and chemical composition of 376 hot springs in Korea. It took about three days for the temperature to stabilize after the pumping test. After the stabilization, in-situ and laboratory analyses of the hot spring water were carried out. The average temperature and TDS were $29.95^{\circ}C$ and 2,071mg/L, respectively. The temperature ranging $25-30^{\circ}C$ were recorded from 70% of hot springs, and $30-35^{\circ}C$ of 15.4%. The maximum temperature was about $78^{\circ}C$. The value of TDS in 79% of the wells was below 1,000 mg/L. 5.5% of the wells, mostly developed near seashore, shows higher values than 10,000mg/L of TDS suggesting the influence of seawater. The hot spring water shows 8.49 of pH representing a weak alkali. For the mineral compositions dissolved in the hot spring in Korea, Na (431 mg/L) and Ca (188 mg/L) are the major cations, and Cl (840 mg/L) and $SO_4$ (213 mg/L) are the major anions.

• KSBB Journal
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• v.29 no.5
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• pp.336-342
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• 2014

Asexual benthic polyp reproduction plays a major role in the jellyfish bloom. Recent studies found that temperature is the most important factor to regulate the budding rate of the polyps. We established a simple dynamic model to count the number of polyps depending on the variation of temperature with two data sets from different places. The population of polyps was counted through the budding rate and the number of budding times by Fibonacci sequence. It is assumed that the budding rate depends on the temperature only. The budding rate of the asexual reproduction shows very sensitive to the distribution of the seawater temperature. The model was tested to the temperature data of Ansan located in the west sea of Korea. The results indicate that this model can be useful to predict the blooms of Aurelia aurita polyps, which may have considerable influence on the bloom of medusa. The shape of temperature curve plays a key role in the predicting the bloom of Aurelia aurita polyps.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.32 no.5
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• pp.601-606
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• 1999

Physiological responses of cultured olive flounder (Paralichthys olivaceus) on lowering seawater temperature sharply and continuously were studied with 4 experiments of temperature changes (Exp.I$\~$IV). In Exp.1, the temperature was decreased from $18^{\circ}C$ to $9^{\circ}C$ by the rate of $1^{\circ}C$/hr, thereafter back to the initial temperature after 5 dars. With the same conditions of temperature rate and 5 days interval, the temperature changes for Exp.II, III and IV were $20^{\circ}C$ to $17^{\circ}C,\;23^{\circ}C$ to $14^{\circ}C$ and $23^{\circ}C$ to $17^{\circ}C$, respectively, Serum cortisol and glucose were measured during whole experiments. Hematocrit (Ht), hemoglobin (Hb), red blood cell (RBC) and mean corpuscular hemoglobin concentration (MCHC) were measured in the Exp.I, and osmolality, electrolytes ($Na^+,\;Cl^-,\;K^+,\;Ca^{2+}$), total protein, aspartate aminotransferase (AST) and alanine aminotransferase (ALT) of serum, in Exp.II$\~$IV. Serum cortisol levels were significantly increased by the lowering temperature sharply during whole experiments, while serum glucose levels were increased only in Exp,III and IV. Ht, RBC and Hb were decreased as the water temperature was lowered, but MCHC was increased. The serum osmolality was reduced and the unstable changes of electrolytes were shown by the changes of seawater temperature. No significant changes in total protein, ALT and AST activity were observed.

• Journal of Advanced Marine Engineering and Technology
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• v.38 no.7
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• pp.883-889
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• 2014

It is generated for cavitation erosion due to the local static boiling by pressure differentials in high speed rotating fluid environment. The cavitation is influenced by various elements such as pressure, velocity, temperature, pH of fluid and medium. In particular, the damage of material is accelerated due to the electrochemical corrosion by $C1^-$ and cavitation erosion due to cavities in seawater. In this paper, hence, it investigated for martensite stainless steel the damage behavior with applied current density and cavitation time in natural seawater solution. Less damage depth at the cavitation condition was observed than static condition as a result of galvanostatic experiment. Furthermore, it was shown that dramatic increase of weightloss, damage rate and damage depth after 3 hour of cavitation test.

• Journal of The Korean Society of Agricultural Engineers
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• v.51 no.6
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• pp.53-62
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• 2009

The EFDC (Environmental Fluid Dynamics Code), a numerical model for simulating three-dimensional (3D) flow, transport, and biogeochemical processes in surface water systems including rivers, reservoirs, and estuaries, was applied to assess the effect of sea water and fresh water exchange rates ($Q_e$) on the mixing characteristics of a conservative pollutant (tracer) induced from upstreams and salinity in Saemangeum Lake, Korea. The lake has been closed by a 33 km estuary embankment since last April of 2006, and now seawater enters the lake partially through two sluice gates (Sinsi and Garyuk), which is driving the changes of hydrodynamic and water quality properties of the lake. The EFDC was constructed and calibrated with surveyed bathymetry data and field data including water level, temperature, and salinity in 2008. The model showed good agreement with the field data and adequately replicated the spatial and temporal variations of the variables. The validated model was applied to simulated the tracer and salinity with two different gate operation scenarios: RUN-1 and RUN-2. RUN-1 is the case of real operation condition ($Q_e=25,000,000\;m^3$) of 2008, while RUN-2 assumed full open of Sinsi gate to increase $Q_e$ by $120,000,000\;m^3$. Statistical analysis of the simulation results indicate that mixing characteristics of pollutants from upstream can be significantly affected by the amount of $Q_e$.

• Journal of Environmental Health Sciences
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• v.29 no.2
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• pp.94-102
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• 2003

This study was carried out to investigated the distribution and characteristics of Vibrio spp. isolated from fish and shellfish, seawater and brackish water samples collected from Pohang, Uljin, Yeongduk and Gyeongju in Gyeongbuk Province from April 2000 to October 2000. Total 155 strains of genus Vibrio were isolated from 439 collected samples, and numbers of isolated strains of V. parahaemolyticus and V. vulnificus were 140 and 15, respectively. The isolation rate from the samples collected in Pohang was the highest as 41.5% (76 strains), and wat the highest as 71.4% (30 strains) in brackish water, and was the highest as 55.7% (34 strains) in August. And the optimal pH, temperature, and NaCl concentration for growth of V. parahaemolyticus and V. cholerae were 8.0, 3$0^{\circ}C$ and 2.0％, respectively. In a resistance test for environmental factors, heat and cold resistants of V. parahaemolyticus were higher than those of V. vulnificus, withstanding for 15 minutes at 6$0^{\circ}C$ and 6 days at -18$^{\circ}C$. The pH range for existence of V. parahaemolyticus and V. vulnificus were 4.5~l1.0 and 4.5~10.0, showing the similar resistance to pH. V. parahaemolyticus and V. vulnificus could grow in media containing up to 10.0% and 7.0% NaCl, respectively, Salt-tolerance of V. parahaemolyticus was higher than that of V. vulnificus. In an antibiotics sensitivity test against 16 strains of V. parahaemolyticus, twelve strains were resistant to ampicillin, eight strains were resistant to cephalothin. one strain was resistant to streptomycin, and one strain was resistant to ticarcillin.

• Journal of Advanced Marine Engineering and Technology
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• v.38 no.10
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• pp.1244-1250
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• 2014

The temperature of the main engine cabin of commercial vessel is very high. The material SS-316L undergoes creep damage at temperatures exceeding $450^{\circ}C$. It is essential to maintain the highly stressed engine cabin below the creep regime. Hence, seawater is employed in this kind of maritime vehicles as cooling liquid. It obtains the thermal energy at the cooling pipe line after passing through main engine cooling system. To harness the energy in the seawater, a turbine can be installed to absorb the energy in the seawater before being released into the sea. In this study, a cooling pipe line is selected to apply the tubular type hydro turbine for transferring the energy. Numerical analysis for investigating the performance and the internal flow characteristics of the tubular turbine is conducted. The results show that the maximum efficiency of 85.8% is achieved although the efficiency drops rapidly at partial flow rate condition. The efficiency descends slowly at the condition of excess flow rate. There is a relatively wide operating range of flow rate of this turbine to keep high efficiency at the excess flow rate condition. For the internal flow of the turbine, there is uniform streamline on the suction and pressure sides of the blade at the design point. However, the secondary flow appears at the suction and pressure sidesat the excess flow rate.In addition, it appears only at pressure side at the partial flow rate condition.

• 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.

• Korean Journal of Microbiology
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• v.35 no.1
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• pp.53-60
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• 1999

The biodegradation of recalcitrant polycyclic aromatic hydrocarbon, pyrene was investigated in microcosm simulating the beach sand and seawater. The natural biodegradation rates of pyrene were between 30-2,200 ng/g(ml)/day in beach sand and seawater when the pyrenc loading rates were 100- 1,000 ppm at 5-$20^{\circ}C$. The effects of the inoculum size, pyrene concentralion, incubation temperature and surfactant addition were investigated in fertilized (Inipol EAP 22) samples. Generally the biodegradation in beach sand was higher than that in seawater. A mixed inoculum (Pseudomonus, Acinetobacter, Moruxella) showed the 3,120 nglglday of biodegradation rate in beach sand with 200 ppm pyrene, which was 7.8 times higher than the natural biodegradation rate. The highest transformation rate, 4,860 ng/g/day was obtained in the bioaugmented beach sand (1,000 ppm pyrene). The glucose and surfactant addition to enhance the removal have negatively influenced on the biodegradation of pyrene. In case ol surfactants, CMC (critical micell concentration) might bc the control factor for the biodegradation.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.38 no.6
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• pp.347-352
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• 2005

These experiments investigated the conditioning pattern and the nitrification efficiency of a fluidized sand biofilter (FSB) for seawater application. The FSB fed artificial nutrient was fully conditioned within 22 weeks. The maximum nitrification efficiency of the FSB was achieved at a superficial water velocity (SWV) of 1.0 cm/sec. After fixing the superficial water velocity at 1.0 cm/sec, the nitrification rates of the FSB were assessed at 3 total ammonia nitrogen (TAN) loading rates (250, 500, 1,000 g TAN/$m^3$/day) and 3 water temperatures (12, 16, $20^{\circ}C$). The TAN concentration in the simulated culture tank ranged from 2.87 to 9.72 mg/L at TAN loading rate of 1,000 g TAN/$m^3$/day, while that ranged from 0.45 to 1.26 mg/L at TAN loading rate of 500 g TAN/$m^3$/day. The ranges of TAN concentration in the former were too high for aquatic organisms and those in the latter were acceptable. Therefore, the safe TAN loading rate for the FSB in seawater conditions was decided as 500 g TA/$m^3$/day. From these results, daily TAN removal rates (g TAN/$m^3$/day) of FSB under conditions of inlet TAN concentration (C, mg/L) and water temperature (T, $^{\circ}C$) were calculated by the following non-linear multi-regression equation: TAN removal rate: f(z)=-1,311.295+655.714LnT+225.775LnC ($r^2=0.962$).