• 한국환경과학회지
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• 제6권3호
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• pp.239-247
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• 1997

The numerical experiments using a particle tracking model have been performed for predicting the change of water Quality and shoreline. In present study, comparison of the numerical model results with the analytic solution shows that the point of the mainmum concentration and the distribution pattern is very similar. The reflection effect from the boundary was newly Introduced for making clear the effect of the closed boundary which set limits to application of a particle tracking model. The present model seems to reappear physical phenomenon well. This model shows well qualitative appearance of pollutant diffusion in Kwangan beach. Therefore, this model is regarded as a useful means for predicting diffusion movement of suspended sand, and change of water quality.

• 한국환경과학회지
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• 제5권3호
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• pp.347-359
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• 1996

A study was carried out on the distribution of chlorophyll a and water quality in the dry season in Yosuhae bay and adjoining sea, Southern Korea, in July of 1994. Concentration of salinity and phosphate were lower in the outer bay than in the inner bay. While nitrate and silicate were higher in the former than in the latter. We were identified with coastal waters of origin from China with the lower salinity in outer bay. The China coastal water was characteristic of high nutrients and phytoplankton biomass, such as chlorophyll a. The principal component analysis-(PCA) on the analytical data proved that high density of phytoplankton biomass , occurred under the condition of low salinity and high concentration of nissoived Inorganic nutrients. It is thought that the thermoharine structure and biological produtions of Yosuhae bay were controlled by the China coastal water in the outer bay.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 1998년도 Proceedings of International Symposium on Remote Sensing
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• pp.58-63
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• 1998

The aim of the present study is to define and tentatively to interpret the distribution of polluted water released from Lake Sihwa into Yellow Sea using Landsat TM. Since the region is an extreme case 2 water, empirical algorithms for chlorophyll-a and suspended sediments have limitations. This work focuses on the use of multi-temporal Landsat TM. We applied PCA to detect evolution of spatial feature of polluted water after release from the lake. The PCA results were compared with in situ data, such as chlorophyll-a, suspended sediments, Secchi disk depth (SDD), surface temperature, radiance reflectance at six bands. The in situ remote sensing reflectance was analysed with PCA. On the basis of these In situ data we found good correlation between first Principal Component and Secchi disk depth ($R^2$=0.7631), although other variables did not result in such a good correlation. The problems in applying PCA techniques to multi-spectral remote sensed data are also discussed.

• 한국수산과학회지
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• 제35권4호
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• pp.348-355
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• 2002

To know characteristics of water quality in Saemankeum area, we were investigated the water quality of surface layer from July of 1999 to June of 2000. The concentrations of COD and chlorophyll a were in the range of $0.64\~6.40$ (mean 1.96)mg/L, $1.95\~51.55$ (mean 11,07)$mg/m^3$, respectively. The annual mean concentrations of DIN, DIP were found to be 21.182 $\mu$g-at/L and 0,655 $\mu$g-at/L respectively, which were exceeding second grade of seawater quality standard. The nitrogen ratio to the phosphorus was lower than 1. Therefore, nitrogen was playing an important role in phytoplankton growth as limiting factor in study area. Mean values of eutrophication index were exceeding 1, which was the eutrophication criteria. Especially Mankyung and Dongjin estuary were shown over 10 as eutrophication index. Therefore, Saemankeum area could be evaluated to possibility area for eutrophication. Released rate for ammonia nitrogen and phosphate phosphorus from sediments were 62.92 ${\mu}g-at/m^3/hr$ and 6.71 ${\mu}g-at/m^3/hr$, respectively.

• 환경생물
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• 제29권2호
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• pp.98-106
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• 2011

마산만의 수질변화와 chlorophyll-$a$의 관계를 밝히고자 이 해역을 대표할 수 있는 4개 정점에서 2010년 2월부터 2010년 11월까지 강우와 기온을 포함한 기후학적 요인, 물리 화학적 요인, 그리고 chlorophyll-$a$의 변화를 집중 조사하였다. 그 결과, 수온, 염분, SS, 규산염은 정점별 차이를 보이지 않았으며, COD 및 DIN은 마산만 내만으로 갈수록 증가하였다. 시계열적으로는 여름철 집중 강우 시 마산만 지류 하천 및 낙동강을 통해 담수가 유입되면서 염분의 급강하 및 SS량과 COD의 증가가 나타났다. 영양염류 중 DIN은 여름철 집중강우 시 일시적으로 증가하는 양상을 제외하고는 낮은 농도를 보였고 DIP와 규산염 또한 DIN과 유사한 양상을 보였다. 마산만에서 식물플랑크톤 성장에 영향을 주는 영양염류는 봄철 중반까지 규소와 인이 성장제한인자로 작용하고, 늦봄부터 가을까지는 질소원이 주 성장제한요인으로 작용할 것으로 판단된다. 다중회귀분석을 실시한 결과, 늦겨울부터 봄철까지 chlorophyll-$a$ 농도는 수온, 염분, COD, DIP의 변화에 의해 영향을 받고 있었다. 여름철에는 봄철과 달리, 염분 및 COD, 강수량이 영향을 주고 있어, 여름철 집중강우에 따른 영향인자들에 의해 chlorophyll-$a$가 빠르게 변화됨을 알 수 있었다. 따라서 마산만 해역의 chlorophyll-$a$의 변화는 영양염류와 같은 화학적 인자의 영향과 함께, 수온 및 강수와 같은 물리적 인자에 의해 크게 영향을 받고 있다.

• 환경위생공학
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• 제21권3호
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• pp.61-72
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• 2006

This study was carried out for verification of efficiency of seawater exchange breakwater which was installed in joomoongin harbor for the first time in our country. The joomoongin harbor, where seawater exchange breakwater has been constructed, shows typical for fishery and tourist port city specifics of greatest pollutants discharge volume in spring and summer, when tourist inflow and fishery activity is most vigorous. On the East Sea seawater flux through seawater exchange breakwater for the smallest waves (up to 0.5 m) was found out to be $1,526-3,052m^3/day$. After construction of seawater exchange breakwater, Zone 1 and Zone 2 of stagnant water inside the port were found to be a lot improved. Zone 3, adjacent to outport area, was found to be lower comparing with Zone 1 and Zone 2. The results of statistical analysis show that comparing with water quality improvement effect before and after seawater exchange, water quality after installation of seawater exchange breakwater became much better, primarily because of physical change around the harbour.

• 동아시아식생활학회지
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• 제11권3호
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• pp.196-203
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• 2001

This study was conducted to provide basic data for the development of natural seasoning. The quality chatacteristics of water exacts from Pleurotus ostreatus and Lentinus edodes were determind. Also, savory taste, fragrance, color and overall preference was evaluated. The preference test on the seasonings prepared from Pleurotus ostreatus and Lentinus edodes with the addition of sea tangle was also performed. The crude protein content of dried, Lentinus edodes and Pleurotur ostreatus was 20.4% and 30.4% respectively. The total organic acid contents were higher in Plourotus ostreatus than in Lentinus edodes extracts. The total free amino acid adn total nucleotide contents were higher in Pleurotus ostreatus than in Lentinus edodes extracts. Three nucleotide, adenosine monophosphate(AMP) , guanosine monophosphate(GMP), xanthine monophosphate(XMP) were found in mushroom seasonings while inosine monophosphate(IMP) was not detected. Pleurotus ostreatus extract showed higher score in savory taste and overall acceptability than Lentinus edodes extract, Pleurotur ostreatus seasoning added with 1% sea tangle and Lentinus edodes seasoning added with 1.5% sea tangle were rated as high in overall quality In a sensory test of foods cooked with mushroom seasoning. It was shown that panels in their twenties well used to the taste of monosodium glutamate while the people in their thirties preferred the specific flavor of the mushroom seasoning.

• 한국건축시공학회지
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• 제3권3호
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• pp.107-112
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• 2003

This study is to investigate the properties of concrete with crushed sand on site and to propose a quality guideline for its use as artificial sand and concrete. From our experimental result in laboratory and site, we found that demand water of concrete with crushed sand for target slump increased by 18kg/m3 compared to mixed sand and l8kg/m3 compared to sea sand respectively. The compressive strength increased by around 3∼6% when compared to concrete with sea sand. Accordingly, our study showed that the combined sand mixed with sea sand would be desirable to obtain workability and strength of concrete including dry shrinkage and bleeding test. Furthermore, the optimal replacement percentage of crushed sand was 50% with sea sand. As such, crushed sand would be sufficient as fine aggregate for concrete in terms of economic efficiency and quality. Crushed sand, on the other hand can only be used as fine aggregate when VFS(Very Fine Sand) is below 3.5 percentage of weight of sand and particle shape is above 55 percentage. Also, the particle shape and microsand passing NO.200 sieve should continually be improved to increase workability of concrete on site.

• Environmental Engineering Research
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• 제25권4호
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• pp.515-521
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• 2020

Nowadays, due to various pollution sources, it is essential for environmental scientists to monitor water quality. Phytoplanktons form the end of the food chain in water bodies and are one of the most important biological indicators in water pollution studies. Chlorophyll-A, a green pigment, is found in all phytoplankton. Chlorophyll-A concentration indicates phytoplankton biomass directly. Therefore, Chlorophyll-A is an indirect indicator of pollutants, including phosphorus and nitrogen, and their refinement and control are important. The present study, Moderate Resolution Imaging Spectroradiometer (MODIS) satellite images were used to estimate the chlorophyll-A concentration in southern coastal waters in the Caspian Sea. For this purpose, Multi-layer perceptron neural networks (NNs) were applied which contained three and four feed-forward layers. The best three-layer NN has 15 neurons in its hidden layer and the best four-layer one has 5 in each. The three- and four- layer networks both resulted in similar root mean square errors (RMSE), 0.1($\frac{{\mu}g}{l}$), however, the four-layer NNs proved superior in terms of R² and also required less training data. Accordingly, a four-layer feed-forward NN with 5 neurons in each hidden layer, is the best network structure for estimating Chlorophyll-A concentration in the southern coastal waters of the Caspian Sea.

• 한국표면공학회지
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• 제49권5호
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• pp.439-446
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• 2016

In 2015, a fin tube (Cu-Ni 70/30 alloy) of package type heat exchanger for navy vessel was perforated through the wall which led to refrigerant leakage. This failure occurred after only one year since its installation. In this study, cause of the failure was determined based on available documents, metallographic studies and computational fluid dynamics simulation conducted on this fin tube. The results showed that dimensional gap between inserted plastic tube and inside wall of fin tube is the cause of the swirling turbulent stream of sea water. As a result of combination of swirling turbulence and continuing collision of hard solid particles in sea water, erosion corrosion has begun at the end of inserted plastic tube area. Crevice corrosion followed later in the crevice between the outer wall of plastic tube and inner wall of fin tube. It was found that other remaining tubes also showed the same corrosion phenomena. Thorough inspection and prompt replacement will have to be accomplished for the fin tubes of the same model heat exchanger.