• 한국미생물·생명공학회지
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• 제35권3호
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• pp.210-219
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• 2007

본 연구는 제주도 자생식물 4종(Microlepia marginata panzer Christ., Prunella vulgaris. aleutica Fernald, Perilla-frutescens var. japonica Hara., Gleichenia japonica Spreng)을 부위별로 나누어 각 부위를 열수 추출하여 각 추출액을 농도별로 첨가하여 E. faecitum KCCM 12118, L. rhamnosus KCCM 32826, L. plantarum KCCM 11542, P. pentosaceus KCCM 40464 균종에 대한 생육조건 및 배양액을 가지고 어류 질병 미생물에 대한 항균활성 및 DPPH 라디칼 소거활성 및 Hydroxyl radical 소거활성을 조사하였다. 자생식물 추출액을 농도별로 첨가하여 4종의 lactic acid bacteria를 72시간 배양하면서 생육활성을 보았을 때 10%를 첨가하여 48시간 배양하였을 때가 가장 좋은 생육 조건임을 알 수가 있었으며, 또한 lactic acid bacteria 생육시 자생식물 추출물 첨가가 lactic acid bacteria 증식에 효과가 있음을 나타내었다. DPPH 라디칼 소거활성에서는 꿀풀 잎 추출물을 10% 첨가하여 배양하였을 때 합성 항산화제인 BHA(90%)와 BHT(81%) EDA를 비교하였을 때 BHA와 유사하거나 조금 높은 활성을 BHT보다는 높은 라디칼 소거활성을 나타내었다. Hydroxyl radical 소거활성은 5% 자생식물 추출물을 첨가한 배양액에서부터 BHT보다 높은 소거활성을 나타내기 시작하여 10%를 첨가한 배양액에서는 BHA보다 높은 소거 활성을 나타내었다.

• 한국해양환경ㆍ에너지학회지
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• 제18권3호
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• pp.157-165
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• 2015

본 연구는 고리원자력발전소와 신고리원자력발전소로부터 배출되는 온배수의 영향을 받는 해역에서 퇴적물 특성과 대형 저서동물의 군집구조를 조사하고 비교하였다. 두 배출해역의 퇴적물 특성들 중에서 모래와 펄, 유기물의 함량이 통계적으로 유의한 차이를 보였다. 대형 저서동물의 출현종과 개체 수는 고리원자력발전소보다 신고리원자력발전소의 배출해역에서 더 많았으며, 그 수는 이전의 다른 연구결과들과 유사한 수준이었다. 두 원자력발전소의 온배수 배출해역은 퇴적물 특성과 대형 저서동물의 출현종 수에서 유의한 차이를 보였다.

• Journal of Advanced Marine Engineering and Technology
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• 제21권3호
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• pp.278-283
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• 1997

The rectifier is the main element in the telecom DC power system. This paper investigates the advantages and disadvantages of three rectifier techniques ; thyristor, ferro - resonant, and switched - mode. Compared with other techniques, the switched - mode rectifier tech¬nique offers several advantages such as higher efficiency, smaller size and weight, and lower audible noise. Technical requirements in telecom rectifier plant are also described. Finally, the future trends in telecom powering are discussed in connection with the advance oftelecom net¬works.

• 한국마린엔지니어링학회:학술대회논문집
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• 한국마린엔지니어링학회 2012년도 전기공동학술대회 논문집
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• pp.119-120
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• 2012

In the various industry plant, it need a condition monitoring system for an active machine that used an detachable wireless sensors. In this paper, IEEE802.15.4 standard based detachable wireless sensor monitoring system configure results will be introduced.

• Journal of Plant Biology
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• 제23권2호
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• pp.55-60
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• 1980

The quantity of heavy metals (As, Cd, Cu, Pb, Zn) contained in marine algae collected in Onsan-myon on the east coast of Korea from March to December 1978 was determined as a part of the environmental base line survey of the Onsan Industrial Base. In general, green algae have a higher Cu content than either brown or red algae, and brown algae have higher As and lower Cu contents, while red algae have a higher Zn content. Significant differences between algal species in either Cd or Pb content were however not found.

• Journal of Advanced Marine Engineering and Technology
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• 제27권3호
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• pp.388-394
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• 2003

Hydraulic system is difficult to obtain a suitable performance due to the nonlinearity load pressure change and system parameter variation. The requirement of control a1gorithm has been complex in order to satisfy the performance. The adaptive control is a control method which is suggested to achieve the control object under the plant characteristics change. In spite of the case that plant characteristics and the degree of variation are difficult to grasp. the adaptive control could keep the characteristics of closed-loop system generally. In this study. a method of combined generalized minimum variance adaptive control (GMVAC) and output error feedback is proposed, in order to solve the problem of non-minimum phase of plant and the vibration and overshoot in initial response. The control performance according to the variation of characteristics of plant is evaluated by changing the supply pressure. The experimental results show the effectiveness of the proposed scheme.

• Nuclear Engineering and Technology
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• 제52권2호
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• pp.366-372
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• 2020

Using several accessible published data sets, we analyzed the temporal change of ¹³⁷Cs radioactivity (per unit mass of sample) in marine sediments and investigated the effect of the water content of sediment on the ¹³⁷Cs radioactivity, to understand the behavior of ¹³⁷Cs present in marine environments. The ¹³⁷Cs radioactivity in sediments decreased more slowly in the Baltic Sea (near the Chernobyl nuclear power plant) than in the ocean near the Fukushima Daiichi nuclear power plant (FDNPP). The ¹³⁷Cs radioactivity in the sediment near the FDNPP tended to increase as the water content increased, and the water content decreased at certain sampling sites near the FDNPP for several years. Additionally, the decrease in the water content contributed to 51.2% of the average ¹³⁷Cs radioactivity decrease rate for the same period. Thus, it may be necessary to monitor both the ¹³⁷Cs radioactivity and the water content for marine sediments to track the ¹³⁷Cs that was discharged from the sites of Chernobyl and Fukushima nuclear power plants where severe accidents occurred.

• Fisheries and Aquatic Sciences
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• 제13권3호
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• pp.236-243
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• 2010

Fecal sterols, nonylphenolic compounds (NPs), and polycyclic aromatic hydrocarbons (PAHs) were determined in surface water from Masan Bay and its adjacent rivers in February 2005. Concentrations of coporstanol (Cop), an indicator of fecal pollution, in surface water ranged from <10 to 13,853 ng/L, and concentrations of nonylphenol, the most toxic of the NPs, ranged from 10.2 to 481 ng/L, and concentrations of PAHs ranged from 8.61 to 223 ng/L. The concentrations of the compounds measured in this study were lower than or comparable to those at other locations in Korea and other countries. The contamination of Cop and PAHs in surface water was associated with the discharge from rivers passing through cities and/or industrial complexes. The NP contamination was associated with wastewater treatment plant (WWTP) effluents through outfalls as well as riverine discharge. Compared to ecotoxicological values, the concentrations of NPs from rivers, the mouths of rivers, and WWTP outfall areas exceeded guidelines, suggesting that hot spot areas may pose a potential risk to sensitive species.

• 한국해양공학회지
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• 제34권4호
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• pp.263-271
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• 2020

In this study, we performed a three-dimensional (3D) topology optimization of a fixed offshore structure to enhance its structural stiffness. The proposed topology optimization is based on the solid isotropic material with penalization (SIMP) method, where a volume constraint is applied to utilize an equivalent amount of material as that used for the rule-based scantling design. To investigate the effects of the main legs of the fixed offshore structure on its structural stiffness, the leg region is selectively considered in the design domain of the topology optimization problem. The obtained optimal designs and the rule-based scantling design of the structure are manufactured by 3D metal printing technology to experimentally validate the topology optimization. The behaviors under compressive loading of the obtained optimal designs are compared with those of the rule-based scantling design using a universal testing machine (UTM). Based on the structural experiments, we concluded that by employing the topology optimization method, the structural stiffness of the structure was enhanced compared to that of the rule-based scantling design for an equal amount of the fabrication material. Furthermore, by effectively combining the topology optimization and rule-based scantling methods, we succeeded in enhancing the structural stiffness and improving the breaking load of the fixed offshore structure.

• ALGAE
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• 제21권4호
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• pp.453-461
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• 2006

This study is intended to clarify the structure and seasonal dynamics of warm tolerant benthic marine algal community in Korea. The species composition and biomass of marine algae at the discharge canal of Wolseong nuclear power plant on the East Coast of Korea were investigated seasonally from February 2001 to October 2005. As a result, 43 species (6 blue-green, 8 green, 9 brown and 20 red algae) of marine algae were found at the discharge canal during the past five years. In general, the number of species observed was abundant during winter to summer and less in autumn. Lyngbya confervoides and Enteromorpha compressa always occurred at the discharge canal during the past five years, and Oscillatoria brevis, Padina arborescens and Caulacanthus ustulatus were common species found more than 80% frequency during the study period. Seasonal fluctuations of mean biomass were 2-659 g dry wt m–2 and dominant species in biomass were Caulacanthus ustulatus (contribution to a total biomass proportion 37%), Enteromorpha compressa (26%) and Padina arborescens (24%). Results showed that, in the floristic composition, the green algae occurred as common algal group at the discharge canal of Wolseong nuclear power plant. In the quantitative aspect, however, the red algae such as Caulacanthus ustulatus and Ahnfeltiopsis flabelliformis appeared as predominant group at the discharge canal, in contrast to Kori nuclear power plant where there was a definite green algal dominance. Differences in algal communities developed at the discharge canals of three nuclear power plants on the East Coast of Korea can probably be related to local environmental factors.