• Journal of the Korean Society of Food Science and Nutrition
• /
• v.22 no.5
• /
• pp.621-628
• /
• 1993

Total lipid contents from 10 species of marine algae(2 green, 5 brown, and 3 red algae) collected from different places in Korea were examined and their fatty acid compositions were compared among species and habitats. Total lipid(TL) was prominent in green laver(about 7.3~10.1%) of the green algae, in sea mustard and seaweed fusiforme(about 3.1~4.8%) of the brown algae and purple laver(about 4.9~6.4%) of the red algae. Sea mustard and seaweed fusiforme collected at Chungmu contained a relatively high level of TL than that at Yosu and Kijang. The TL content of purple laver showed the highest portion in that collected at Nakdong. Green algae comprised the majority of n-3 fatty acids(29.0~66.3%), which mainly consisted of 16 : 4(n-3) (or 16 : 3 (n-3)), 18 : 3(n-3) and 18 : 4(n-3). Brown algae accounted for a low level of n-3 fatty acids(17.9~36.5%) mainly 18 : 4(n-3), 18 : 3(n-3) and 20 : 5(n-3), whereas the brown algae contained a significant level of n-6 fatty acids(7.23~26.5%) such as 20 : 4(n-6) and 18 : 2(n-6). In the case of red algae, the n-3 fatty acids consisted mostly of 20 : 5(n-3) which scored 53% of polyenoic acids in purple laver collected at Nakdong. The proportion of n-3 fatty acids in algae belonging to the same species was higher in algae of high TL contents. Consequently, TL and n-3 fatty acid levels from the seaweeds studied in this paper were different from their habitats.

• Korean Journal of Ecology and Environment
• /
• v.54 no.1
• /
• pp.39-48
• /
• 2021

In order to control algal bloom, which causes environmental problems such as eutrophication in freshwater ecological environments, many attempts have recently been made using biological approaches. Among them is filtration using bivalve. Algae control with filter-feeding bivalves is emerging as an eco-friendly method. In this study, bivalves collected at Baekje weir in Geum River in Korea from Jun to Sep 2020 were tested to find out the possibility of algae control using filter-feeding bivalves through laboratory experiments. The Unio douglasiae, Anodonta woodiana, and Anodonta arcaeformis collected from Baekje weir were put into a water tank (2 L) containing Clorella vulgaris, and as a result, the average filtration rate was 95.9% per animal after 24 hrs. Calculating this with the Chl-a concentration converted to a calibration curve, it was found that the average of 154.84 ㎍ L^-1 of Chl-a was reduced. Based on this calculation, the possibility that one bivalve can eliminate Chl-a in one month is 0.0005%. It is expected that the effect is 20.14% when there are 40,000 animals. These results indirectly showed how effective bivalve's ability to control Chl-a in their habitat is. Although this study was limited to calculating the algae control ability of aquatic ecosystem based on the filtration rate of bivalve and the corresponding Chl-a reduction rate, it is thought that it will be used as basic data for integrated research from various factors and viewpoints (phytoplankton, aquatic plants, benthic organisms, and sediments) through additional research.

• Korean Journal of Ecology and Environment
• /
• v.56 no.2
• /
• pp.151-160
• /
• 2023

Cyanobacteria Pseudanabaena strains are known to produce 2-MIB(odorous material) in freshwater systems, thereby causing problems in water use. However, their physiological responses to environmental factors in relation with 2-MIB production is not well explored. This study was conducted to evaluate the effect of temperature on the growth and 2-MIB production of Pseudanabaena redekei. The experimental cyanobacteria strains were separated from the Uiam Reservoir (North Han River) and cultured in the BG-11 medium. Temperature was set to 10, 15, 20, 25, and 30℃ for the experiment, in the reflection of the seasonal water temperature variation in situ. For each temperature treatment, cyanobacterial biomass(Chl-a) and 2-MIB concentration (intra-cellular and extra-cellular fractions) were measured every 2 days for 18 days. Both maximal growth and total 2-MIB production of P. redekei appeared at 30℃. While intra-cellular 2-MIB contents were similar (26~29 ng L^-1) regardless of treated temperatures, extra-cellular 2-MIB concentration was higher only in high temperature conditions (25~30℃), indicating that the extents of 2-MIB biosynthesis and release by P. redekei vary with temperature. The 2-MIB productivity of P. redekei was much higher in low-temperature conditions (10~15℃) than high temperature conditions (25~30℃). This study demonstrated that temperature was a critical factor contributing to 2-MIB biosynthesis and its release in cell growth (r=0.605, p<0.01). These results are important to understand the dynamics of 2-MIB in the field and thereby provide basic information for managing odorous material in drinking water resources.

• Korean Journal of Remote Sensing
• /
• v.26 no.5
• /
• pp.497-510
• /
• 2010

In this study, comparisons of the backscattering coefficients and the coherence values which had been extracted from SAR (Synthetic Aperture Radar) images such as JERS-1, ENVISAT and ALOS satellites with surface roughness, surface geometric and soil moisture content were carried out. As the results of analysis using the backscattering coefficient and coherence values from SAR images, the coherence was shown high in the region containing more of mud fraction due to higher viscosity of fine grain-size. A lot of tidal channels were well developed in the Ganghwa tidal flat, affecting the drainage of seawater and subsequent soil moisture content by exposure time of tidal flat. The backscattering coefficient. consequently, appeared to be lower in sand flat and mix flat with decrease of soil moisture. In contrast, most mud flats were distributed at high elevation so that soil moisture was not much influenced by seawater. The backscattering coefficient in mud flat seemed to have a relationship with the density of tidal channel. In addition, lowering backscattering coefficients in the all Ganghwa tidal flat was observed when surface remnant water increased according to the amount of rainfall. The correlation between backscattering coefficient, coherence and sediment environment factors in the Ganghwa tidal flat was investigated. In the future, more quantitative spatial analysis will be helpful to well understand the sedimentary influence of various sediment environment factors.

• Journal of the Korean Association of Geographic Information Studies
• /
• v.23 no.4
• /
• pp.140-155
• /
• 2020

This study was conducted to identify the location characteristics of infected farms in the areas where livestock diseases were clustered(southern Gyeonggi-do and Chungcheong-do), analyze the probability of disease occurrence in poultry farms, find out the areas corresponding to the conditions, and use them as the basis for prevention of livestock diseases, selection of discriminatory prevention zones, and establishment of prevention strategies and as the basic data for complementary measures. The increase of one poultry farm within a radius of 3-kilometers increases the risk of HPAI infection by 10.9% compared to the previous situation. The increase of 1m in distance from major roads with two lanes or more reduces the probability of HPAI infection by 0.001% compared to the previous situation. If the distance of the poultry farm located with 15 kilometers from a major migratory bird habitat increases by 15 to 30 kilometers, the chance of infection with HPAI is reduced by 46.0%. And if the distance of the same poultry farm increase by more than 30 kilometers, the chances of HPAI infection are reduced by 88.5%. Based on the results of logistic regression, the predicted probability was generated and the actual area of the location condition with 'more than 15 poultry farms within 3km a radius of, within 1km distance from major roads, and within 30km distance from major migratory birds habitat was determined and the infection rate was measured. It is expected that the results of this study will be used as basic data for preparing the data and supplementary measures when the quarantine authorities establish discriminatory quarantine areas and prevention strategies, such as preventive measures for the target areas and farms, or control of vehicles, by identifying the areas where livestock diseases are likely to occur in the region.

• The Transactions of the Korea Information Processing Society
• /
• v.4 no.5
• /
• pp.1358-1370
• /
• 1997

Client-Sever-Comptuing is now recognized as the most powerful and flexible computing mode of the future.Many companies have already commited significant amount of their corporate IS resources to building the cli-ent-server computing environment.Despite this active interst and commitment,however,results from such cli-ent-sever projects are far from being convincing Among the many factors,we suspect,we supect that the less than less than satisfac-tory client-server experiences are perhaps due to the company's lack of underxtanding its essertial information processing characteristics.We analyze five client-server archiedctures in temrs of seven IS-related crieria.We then develop a contin-gency model to match company's information processing chracteristics to the ideal client-server architecture for the firm.Based on the client-server architecture analysis from the previous step. we recommend specific im-plementation strategies for each-server architecture selected. Finally,on an exploratory level,we look into the three client-server implmentation cases to cases to check the validity of our contingency model.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2001.05a
• /
• pp.591-596
• /
• 2001

Many consumption goods, most notably in network markets including the telecommunications industry, exhibit network externalities. For that reason, standardization is the tore Issue in network markets with powerful positive feedback. firms in the telecommunications industry compete intensively against one another to build on early lead due to w inertia and network externalities. Therefore, a firm's strategies err very important in standards competition. In this paper, we'll examine the patterns of standards competition and cooperation, anti a variety of firms' strategies in the telecommunications industry. And then, we'll examine the trend of the change from standard competition to standard cooperation. After that, we'll suggest the national policies for the preemption.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
• /
• 2010.10a
• /
• pp.31-33
• /
• 2010

ECDIS(Electronic Chart Display and Information System 전자해도정보시스템)와 같이 진보된 IT 기술을 적용한 항해장비는 단순히 항해의 목적으로 사용하는 것 이상으로, 해양환경의 보호와 감시에 응용하는 등의 방법으로 그 활용범위를 직접적이고 적극적으로 확대할 수 있다. 종이해도와 달리, ECDIS는 '시간'이라는 4차원적 요소를 도입함으로써 동적시스템(Dynamic System)으로 전환이 용이하다. 이것은 조석, 조류, 바람과 파도와 같은 시간변수(Time Variables) 데이터를 적용함으로써 가능하다. 이 시간변수들을 어군이동위치, 계절변화에 따른 해저지형, ballast water의 취수를 위한 청수지역 등과 함께 활용을 한다면, green ECDIS를 활용한 green navigation은 현실화가 가능하다. 이에 따라 해상종사자의 환경인식은 뚜렷하게 그리고 유용하게 증가할 것이다. 본 논문에서는 green ECDIS의 개념과 모형의 설계 그리고 프로토타입의 개발을 제안하고자 한다.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
• /
• 2010.10a
• /
• pp.215-217
• /
• 2010

VTS 관할 구역 중 정박지에서의 해양사고가 빈발하고 있음에도 이에 대한 관심이 부족한 실정이다. 우선 울산항의 해양사고 통계를 통해 정박지에서의 해양사고의 비중이 의외로 높다는 것을 밝혔다. 본 연구에서는 정박지에서 투묘를 위한 접근단계에서부터 양묘단계까지 발생할 수 있는 위험성들을 살펴보고, 이에 대한 대책으로 정박지 통항량의 감쇄, 정박지 지정의 전략, 단계별 맞춤형 적극적인 정보 제공, 정박 중 안전관리 방안 강화 등을 제안하였다.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
• /
• 2014.06a
• /
• pp.319-322
• /
• 2014

VTS(Vessel Traffic Center)는 관할해역의 해상교통데이터를 수집하여 해상교통관제를 수행하고 있다. 이러한 해상교통데이터는 가공되지 않는 정보이므로, 관제사 및 선박 등 사용자가 유용하게 활용할 수 있는 형태로의 분석이 필요하다. 이는 객관적인 데이터로 관제사 및 선박에서 해상교통 안전정책을 수립하는데 중요하다. 이를 위해 본 연구에서는 수년간 VTS에 축적되고 있는 BIG DATA를 활용하여 해상교통패턴을 분석하고자 한다. 분석하는 해상교통패턴은 통항분포, 선종별 항적 비교, 예부선의 강 조류 주의구역 판별, 항로상 어선 조업 현황분석 등을 통해 빅데이터를 활용한 관제구역설정, 집중관제구역 검토가 가능하다.