• Korean Journal of Ecology and Environment
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• v.43 no.2
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• pp.232-241
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• 2010

Epilithic diatom communities and water quality were monitored to evaluate the ecological impact of the inflow of Wonju-stream passing through the urban area in the Seom River Watershed. We selected the 14 sampling stations (5 main stream sites and 9 tributary sites), and collected diatom and water samples between October 2007 and September 2008, on the seasonal basis. The results indicate that most water quality parameters showed the site-specific patterns over the study, except for water temperature and dissolved oxygen. The levels of water quality parameters were highest at the site of Wonju stream, whereas the lowest in the upstream sites, and intermediate or gradually decreased in the downstream sites of the Seom river. One species, Achnanthes convergens, showed the highest biomass and frequency over the sites, while three saprophilous species-Navicula goeppertiana, Navicula subminuscula, Nitzschia palea were appeared only in Wonju Stream and other polluted sites. According to trophic diatom index (TDI) values, which were highly correlated with nutrients and EC, the study sites were classified into three classes: upstream and tributary (Class A and B), Wonju Stream (Class D), and mixed zone and downstream (Class C). A cluster analysis supported the result of TDI classification. Therefore, Wonju-stream located in populated urban area exerted the adverse ecological effects on the epilithic diatom community and water quality of the lower Seom River System, although its severity gradually decreased downstream.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.47 no.6
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• pp.908-926
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• 2014

This study investigated the community structure and health assessment of macrobenthic assemblages in Wonmun Bay, in the southern coast of Korea. The total number of species and mean density were 170 species and $1,269\;indivuduals/m^2$, respectively. The major dominant species were the bivalve Theora fragilis ($230{\pm}446\;indivuduals/m^2$) and the polychaetes Lumbrineris longifolia ($180{\pm}339\;indivuduals/m^2$), Sigambra tentaculata ($124{\pm}153\;indivuduals/m^2$), Paraprionospio patiens ($104{\pm}293\;indivuduals/m^2$) and Capitella capitata ($82{\pm}223\;indivuduals/m^2$). Community statistics [cluster analysis and nonmetric multidimentional scaling (NMDS) ordination] revealed that the macrobenthic community structure in the study area was classified into three station groups for both seasons. Several biotic indices based on macrobenthic communities have been developed to assess the ecological quality of coastal ecosystems. In this study, the ecological status was assessed by four biotic indices Shannon's H', the AZTI Marine Biotic Index (AMBI), multivariate-AMBI (M-AMBI) and the Ecological Conservation Index (ECI). The ecological statuses of the macrobenthic communities in Wonmun Bay were poorer in the summer than in the spring. The results of the present study indicate that three biotic indices ( i.e.; Shannon's H', M-AMBI and ECI ) were better correlated with bottom dissolved oxygen than the AMBI in Wonmun Bay.

• Proceedings of the Korea Society for Simulation Conference
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• 1999.10a
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• pp.70-74
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• 1999

발전소 시뮬레이션 시스템 기술은 종합적인 지식을 바탕으로 자료수집 및 분석, 소프트웨어 개발 환경, 수학적 모델, 전산기 구성, 각종 계기류 설계 및 구매 장착 등의 노하우를 알아야만 제작할 수 있는 종합적인 기술이다. 또 지시기반의 기술이며 부가가치가 높은 기술이기 때문에 선진 각국에서는 계측제어 시스템의 기술개발 및 시장 확대를 위하여 힘을 쓰는 동시에 타국으로의 기술정보 유출을 경계하는데 신경을 곤두세우고 있다. 현재 복잡화되어 가고 있는 산업 사회의 전력 수요에 대한 대폭적인 증가 추세에 따라 발전소에서는 보다 효율적이며 합리적이고 경제적인 전력 공급을 위해서 전력 생산에 대한 신뢰성 향상 및 안정성 확보는 물론, 효율성 높은 운전이 절실히 요구되고 있다. 한편, 국내의 시뮬레이션 시스템 분야 기술은 아직도 완벽한 수준에는 미치지 못하며, 이 분야의 기술력 확보 및 신기술 개발은 향후 미래의 모든 시스템산업의 성쇄를 판가름하는 아주 중요한 척도가 될 것이다. 이 중에서 접지 분야는 고전압 혼촉에 의한 저압측 선로의 전압상승 방지, 모선(Bus)이나 전력 기기의 절연보호 및 회로전압의 안정등으로 시스템 성능을 한층 증가 시켜줄 뿐아니라 기기의 오동작이나 낙뇌등으로 인명피해 발생을 없애주는 아주 중요한 분야임에도 불구하고 이 분야의 국내 관련법규등이 미비한 사항이다. 그래서 발전소 분산제어 시스템분야의 장기간 신뢰성 및 안정성을 가지고 있고, 국내에서 많이 사용하는 미국 Bailey의 infi-90 및 독일 ABB의 Procontrol-P를 비교 분석하여 발전소 시뮬레이션 시스템의 접지에 응용 하고져 한다.상호 발생기를 이용한 다양한 시스템 검증 및 분석에 이용할 수 있을 것이다. 본 논문은 가상호 발생기의 구조와 최대 용량 시험 방법을 소개하고, 더 나아가 호 Traffic에 대한 최대 용량 시험뿐 아니라 QoS를 향상시키기 위한 교환 시스템의 제반 성능 시험 및 분석에 이를 이용하기 위해 개선이 필요함을 서술하고자 한다.textrm{m}$~3.4$\mu\textrm{m}$ 범위에서의 투과 및 흡수 스펙트럼을 측정하였다. 결정 성장 결과 B3+, Er3+, Cr3+ 이온은 Ti4+ 이온과 이온의 크기 차이가 심하여 결정의 정상적인 성장을 방해하는 물성을 나타냈고, V5+, Cr3+ 이온은 흑색의 결정, Fe3+ 이온은 적갈색의 결정으로 성장되었다. Al3+, Zr4+, Al3+의 순서로 투과도가 높아지는 것이 관찰되었다. 불순이온의 농도에 따른 영향으로서 Al3+ 이온의 경우 주입농도가 높아질수록 low angle boundary와 oxygen deficiency가 감소하였고, 투과율은 조금 감소하거나 큰 차이가 없는 것으로 나타났다. 반면에 Cr3+ 이온을 주입한 경우 0.003 atomic%에서 최적의 물성을 보였으며, 주입농도가 높아질수록 결정성장이 어려워지고 광의 투과도가 급격히 저하되었다.은 1.3을 나타내었다.로 보인다.하면 수평축과 수직축의 분산 장벽의 비에 따라 cluster의 두께비가 달라지는 성장을 볼 수 있었고, 한 축 방향으로의 팔 넓이는 fcc(100) 표면의 경우 동일한 Ed+Ep값에 대응하는 팔 넓이와 거의 동일한 결과가 나타나는 것을 볼 수 있다. 따라서 이러한 비대칭적인

• Korean Journal of Environmental Biology
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• v.41 no.4
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• pp.720-734
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• 2023

To understand the spatiotemporal distribution pattern of zooplankton and the environmental factors influencing zooplankton abundance in Gomso Bay, major harvesting area of Manila clam (Venerupis philippinarum) in South Korea, zooplankton sampling was conducted four times in autumn (October 2022), winter (January 2023), early spring (March 2023), and spring (May 2023). Among the environmental factors of Gomso Bay, water temperature, chlorophyll a concentration (Chl-a), dissolved oxygen (DO), and pH observed different patterns, while salinity and suspended particulate matter(SPM) showed no significant statistical differences between the survey periods. The zooplankton in Gomso Bay occurred 33, 29, 27, and 29 taxonomic groups during each respective survey period. In October 2022 and May 2023, arthropod plankton were dominated, while in January and March 2023, protozoa were primarily dominant. Among the Arthropods, copepods including Acartia hongi, Paracalanus parvus s. l., Corycaeus spp., and Oithona spp. commonly found along Korean coastal areas of the Yellow Sea, were dominated. Cluster analysis based on zooplankton abundance indicated a single community (stable condition) in each season, attributed to low dissimilarity distances, while three distinct clusters (autumn, winter-early spring, spring) between seasons indicated a highly seasonal environment in Gomso Bay.

• Horticultural Science & Technology
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• v.29 no.5
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• pp.447-455
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• 2011

To investigate the effects of the improvement of postharvest quality on fresh tomato, antimicrobial microperforated (AMP) films were prepared and their antimicrobial abilities were observed. AMP films were made by coating different types of natural antimicrobial agents such as cinnamon, clove, and clary sage essential oils into microperforated (MP) films. Cinnamon essential oil of 10% (v/v) has proven to be very effective as inhibitor of the mold growth on tomato, compared to the clove and clary sage essential oils. Quality changes of fresh tomatoes packed using the natural AMP films (AMP10 and AMP30) and MP films (MP10 and MP30) during storage were evaluated. Total microbial growth, weight loss, firmness, lycopene content, and decay rate as the major quality parameters were monitored over 9 days at $15^{\circ}C$. The oxygen transmission rates and mechanical properties between the natural AMP and MP films were also compared. There was no significant difference in change of oxygen transmission rate, tensile strength and elongation between the AMP and MP films. For storage studies, the freshness of tomato packaged in AMP30 film was higher than that in OPP film (the control), MP10, MP30, and AMP10 films. Especially, AMP30 film exhibited high efficiency compared to the control for tomato decay during storage periods. Based on the results, the microperforation and antimicrobial properties of the packaged films may significantly affect the maintenance of an optimum gas composition within the package atmosphere for increasing the storage life and quality of produce. They were also effective on the inhibition of microbial growth by controlled release of antimicrobial agent at an appropriate rate from the package into the tomato. Natural antimicrobial agent coating microperforated films could use potential functional package as a method of extending the freshness of postharvest tomato for storage.

• Journal of the Korean Society of Marine Environment & Safety
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• v.16 no.4
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• pp.321-337
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• 2010

Long-term trends and distribution patterns of water quality were investigated in the Mokpo coastal areas of the Yellow Sea, Korea from 1979 to 2009. Water samples were collected at 5 stations and physicochemical parameters were analyzed including water temperature, salinity, suspended solids (SS), chemical oxygen demand (COD), dissolved oxygen (DO) and nutrients. Spatial distribution patterns of temperature, pH and DO were not clear among stations but the seasonal variations were distinct except ammonium. The trend analysis by principal component analysis (PCA) during 30 years revealed the significant variations in water quality in the study area. Spatial water qualities were discriminated into 3 clusters by PCA; station cluster 1, 2~4, and 5. Annual water qualities were clearly discriminated into 4 surface water clusters and 2 bottom water clusters by PCA. By this multi-variate analysis, the annual trends were summarized as the followings; water temperature, pH and COD tended to increase from late 1980's, salinity to decrease, phosphate to increase from 1994 and dissolved inorganic nitrogen to increase, due to the input of fresh water same as shown in Kyoungin coastal area, Asan coastal area, Choensoo bay and Gunsan coastal area.

• Economic and Environmental Geology
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• v.42 no.6
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• pp.575-589
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• 2009

Groundwater has been extracted for irrigation in Sacheon-Hadong area, which is close to the South Sea. We analyzed chemical components of groundwater to examine the effects of seawater intrusion and agricultural activities in the study area. Most groundwater samples displayed the Na/Cl concentration ratios similar to that of seawater (0.55) with an increasing tendency of electrical conductivity ($227-7,910\;{\mu}S/cm$) towards the coast. In addition, statistical interpretation of the cumulative frequency curves of Cl and $HCO_3$ showed that 30.1% of the groundwater samples were highly affected by seawater intrusion. Groundwaters in the study area mostly belonged to the Ca-Cl and Na-Cl type, demonstrating that they were highly influenced by seawater intrusion and cation exchange. The result of oxygen-hydrogen isotope analysis demonstrated slightly higher $\delta^{18}O$ ((-8.53)-(-6.13)‰) and ${\delta}D$ ((-58.7)-(-43.7)‰) comparing to mean oxygen-hydrogen isotope ratios in Korea. As a result of nitrogen isotope analysis, the $\delta^{15}N-NO_3$ values ((-0.5)-(19.1)‰) indicate two major sources of nitrate pollution (organic nitrogen in soil and animal and human wastes) and mixed source of the two. However, denitrification may partly contribute as a source of nitrogen. According to factor analysis, four factors were identified among which factor 1 with an eigenvalue of 6.21 reflected the influence of seawater intrusion. Cluster analysis indicated the classification of groundwater into fresh, saline, and mixed ones.

• Korean Journal of Crystallography
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• v.15 no.2
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• pp.59-68
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• 2004

Three crystal structures of dehydrated partially $Co^{2+}-exchanged$ zeolite A treated with 0.6 Torr of K at $300^{\circ}C$ (for 12 hrs, 6 hrs, and 2 hrs) vapor have been determined by single-crystal X-ray diffraction techniques in the cubic space group Pm3m at 21(1)$^{\circ}C(a=12.181(1)\;{\AA},\;a=12.184(1)\;{\AA},\;and\;a=12.215(1)\;{\AA})\;respectively)$. Their structures were refined to the final error indices, R(weight) of 0.090 with 10 reflections, 0.091 with 82 reflections, and 0.090 with 80 reflections, respectively, for which $1>\sigma(I)$. In each structure, all four $Co^{2+}$ and four $Na^+$ ions to be reduced by K atoms. The cobalt and sodium atoms produced are no longer found in the zeolite. K species are found at five different crystallographic sites: three $K^+$ ions lie at the planes of 8-rings, filling that position, ca. 11.5 K^+$ ions lie on threefold axes, ca. 4.0 in the large cavity and ca. 4.0 in the sodalite cavity, and ca. 0.5 $K^+$ ion is found near a 4-ring. ca. three $K^0$ atoms are found deep into the large cavity on threefold axes. In these structures, crystallographic results show that cationic tetrahedral $K_4$ (and/or triangular $K_3$) clusters have formed in the sodalites of zeolite A. The $K_4$ and/or $K_3$ clusters coordinate trigonally to three oxygens of a six-oxygen ring. The partially reduced ions of these clusters interact primarily with oxygen atoms of the zeolite structure rather than with each other. ca. 14.5K species are found per unit cell, more than the twelve $K^+$ ions needed to balance the anionic charge of zeolite framework, indicating that sorption of $K^0$ has occurred. The three $K^0$ atoms in the large cavity are closely associated with three out of four $K^+$ ions in the large cavity to form $K_7^{4+}$ clusters. The $K_7^{4+}$ cluster not interacts primarily with framework oxygens.

• Journal of the Korean Society of Marine Environment & Safety
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• v.17 no.3
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• pp.203-218
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• 2011

Long-term trends and distribution patterns of water quality were investigated in the Yeoja Bay of South Sea, Korea from 1976 to 2010. Water samples were collected at 3 stations and physicochemical parameters were analyzed including water temperature, salinity, hydrogen ion concentration (pH), dissolved oxygen (DO), chemical oxygen demand (COD), suspended solids (SS) and nutrients. Spatial distribution patterns of temperature, pH and DO were not clear among stations but the seasonal variations were distinct except ammonium. The trend analysis by principal component analysis (PCA) during 31 years revealed the significant variations in water quality in the study area. Spatial water qualities were discriminated into 2 clusters by PCA; station cluster 1 and 2~3. Annual water qualities were clearly discriminated into 4 clusters by PCA. By this multi-variate analysis, the annual trends were summarized as the followings; water temperature, COD and SS tended to increase from late 1970's, decreased salinity, and increased phosphate from 1991 to 2001 and increased dissolved inorganic nitrogen. Water quality was showed by the input of fresh water same as those of Kyoungin coastal area, Asan coastal area, Choensoo bay, Gunsan coastal and Mokpo coastal area in the Yeoja Bay.

• Journal of Life Science
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• v.31 no.6
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• pp.559-567
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• 2021

This study compared the nutritional characteristics and antioxidant effects of sea mustards sourced from five different areas (Barammaegi, Gultongmeori, Chanmulgae, Johongtaek, and Goraedeung) in Taejongdae, Youngdo, Busan. The contents of total flavonoids and phenols and fatty acid composition were measured. To evaluate their antioxidant effects, 1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2,2'-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) assays were used. Acetone/methylene chloride (A+M) extracts from all the sea mustards contained higher amounts of total flavonoids and phenols than methanol (MeOH) extracts. Among the sea mustards obtained from the different areas, the total flavonoid and total phenolic content of the A+M extract of the sea mustard from Gultongmeori was 1.44±0.04 mg/g and 1.72±0.06 mg/g, respectively. In terms of the fatty acid composition, the Gultongmeori sea mustard had higher percentages of total n-6, total n-3, eicosapentaenoic acid (EPA, 20:5n-3), and docosahexaenoic acid (DHA, 22:6n-3) than the sea mustards from the other areas. The A+M extract of the sea mustard from Gultongmeori was more effective in terms of scavenging free radicals as compared with that of the other sea mustards, as assessed by the DPPH and ABTS assays (p<0.05). In a 120-minute reactive oxygen species (ROS) production assay, all the extracts tested decreased cellular ROS production induced by H₂O₂ compared to that produced by exposure to an extract-free control (p<0.05). The extracts from Barammaegi and Gultongmeori had a greater inhibitory effect on cellular ROS production. These results indicated that the antioxidant effects of sea mustards might be associated with a higher amount of flavonoids and phenols. This study suggests that food-processed products from sea mustard can be developed as functional foods for promoting health in the local population.