• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2010년도 추계학술대회 초록집
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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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• 제29권5호
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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.

• 한국수산과학회지
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• 제32권5호
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• pp.601-606
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• 1999

냉수대로 인한 양식넙치 (Paralichthys olivaceus)의 생리적 반응을 알아보기 위하여, 4차례의 수온 급강하 조건 (Exp.I$\~$IV)을 설정하여 사육실험을 실시하였다. Exp.I에서는 개시시 $18^{\circ}C$에서 9시간만에 $9^{\circ}C$까지 급격히 수온을 떨어뜨린 다음 3시간만에 $12^{\circ}C$로 상승시켜 3일간 두었다가 다시 6시간만에 개시시 수온인 $18^{\circ}C$로 상승시켰다. Exp.II, III 및 IV에서는 각각 $3^{\circ}C$ ($20^{\circ}C), $9^{\circ}C$ ($23^{\circ}C) 및 $6^{\circ}C$ ($23^{\circ}C)의 수온차를 주어 5일간 둔 다음, 다시 원래의 수온으로 올려 주었고, 수온 구배는 시간당 $1^{\circ}C$씩 하강 또는 상승시켰다. 모든 실험에서 넙치의 혈청 코티졸과 글루코스를 측정하였고, Ht Hb, RBC 및 MCHC는 Exp.I에서, 혈청의 삼투질 농도, 전해질 지수 ($Na^+,\;Cl^-,\;K^+,\;Ca^{2+}$), 총단백질량, 아미노기 전이효소인 ALT 및 AST 활성의 변화는 Exp.II, III 및 IV에서 조사하였다. 코티졸 농도는 모든 실험에서 수온의 급강하에 의해 유의하게 증가하였고, 특히 수온변화의 폭이 클수록, 수온이 낮을수록 변화폭이 컸다(Exp.I>III>II>IV). 글루코스 농도는 Exp.I에 있어 유의한 변화 경향을 파악할 수 없었지만, Exp.II에서 수은이 급강하할 때 다소 상승하였고, 수온충격의 횟수가 증가함에 따라 (Exp.III과 IV) 유의하게 상승하였다. Ht, RBC, Hb는 수온 하강에 따라 유의하게 감소한 반면, MCHC는 증가하였다. 4차례의 수온급변에 따라 어체의 삼투질 농도는 감소하였고, 전해질 지수는 안정적이지 못하였다. 혈중의 총단백질량은 다소 감소하는 경향이었으나, ALT 및 AST의 활성은 뚜렷한 증감 경향을 보이지 않았다.

• Journal of Advanced Marine Engineering and Technology
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• 제38권7호
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• pp.883-889
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• 2014

고속유체 환경에서 압력차에 의한 국부적 비등으로 캐비테이션 침식 손상이 발생한다. 캐비테이션은 유체의 압력, 속도, 온도, pH, 그리고 매질 등의 다양한 환경에 영향을 받는다. 특히 해수 용액에서 캐비테이션 환경에 노출될 경우 염소이온에 의한 부식이 캐비티에 의한 침식 손상을 가속화 시킨다. 따라서 본 연구는 마르텐사이트계 스테인리스강에 대해 천연 해수 용액에서 적용 전류밀도와 캐비테이션 시간에 따른 시편 손상 경향을 규명하였다. 정전류 실험 결과 캐비테이션 조건에서 정적인 조건에 비해 비교적 적은 손상 경향이 나타났다. 또한 캐비테이션 실험 결과 3시간부터 급격하게 무게 감소량, 캐비테이션 손상률, 손상깊이가 증가하였다.

• 한국농공학회논문집
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• 제51권6호
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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 $Q_e$.

• 한국환경보건학회지
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• 제29권2호
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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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• 제38권10호
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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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• 제40권6호
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• pp.458-467
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• 2016

소금은 인간의 생리활동에서 매우 중요한 물질로서 섭취한 영양소를 혈액 안으로 수송하는 역할을 한다. 따라서 소금에는 카드늄, 수은, 납, 비소와 같은 유해성분이 전혀 포함되지 않는 것이 가장 이상적이다. 그러나 소금은 모든 물질이 용존 되어 있는 해수로부터 얻어지기 때문에 기술적 한계로 불가불 미량의 유해성분이 포함되는 것을 법적으로 용인하고 있다. 본 논문은 해수의 농도증가에 따른 순차석출 현상을 응용하여 '$15^{\circ}C$ 저온진공건조기술'로 유해성분이 전혀 포함되지 않는 식탁염의 새로운 제조방법에 대한 실험결과를 보고하였다. 본 연구결과를 전통적인 천일염의 제조공정에 확장 적용하면 세계적 명품 소금의 제조도 가능하다.

• 미생물학회지
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• 제35권1호
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• pp.53-60
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• 1999

난분해성 다핵방향족 탄화수소인 pyrene의 생분해를 해수와 해사로 구성된 microcosm에서 조사하였다. 농도 100~1,000 ppm pyrene의 5주동안 자연분해도는 5~$20^{\circ}C$에서 1~11% 이고 이때 전환율은 310~2,200 ng/g(ml).day 이었다. 생분해에 미치는 분해균주 접종량, pyrene 농도, 온도와 계면활성제 첨가의 영향등을 영양염류가 투여된 시료에서 조사하였다. 혼합 분해균주접종시 해수보다는 해사에서 전환율이 전체적으로 높았으며 $10^{7}$cells/ml 접종시 pyrene 200 ppm 농도의 해사에서 대조구보다 분해도가 7.8배 높았다. 가장 높은 전환율 4,860 ng/g/day는 1,000 ppm pyrene이 첨가된 해사에 복합균주를 접종한 시료에서 측정되었다. Glucose 첨가시 해사에서는 배양초기에만 분해도의 증가가 나타났으며, 해수에서는 분해도가 8~10% 증가하였다. 계면활성제와 mineral oil 의 첨가는 오히려 pyrene 분해도를 대부분 감소시켰는데 CMC가 생분해에 큰 영향을 미치는 것으로 판단된다.

• 한국수산과학회지
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• 제38권6호
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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 ($r^2=0.962$).