• 한국해양생명과학회지
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• 제2권2호
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• pp.39-48
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• 2017

생존율은 염분과 관계없이 8℃, 10℃일 때는 98.7~100%였으나, 4℃일 때는 생존율이 25~55%로 나타났다. 혈림프액 내 SOD와 glutathione 농도와 같은 스트레스 지표는 모든 염분구에서 4℃, 6℃일 때 높게 나타났다. THC, hemocyte population, apoptotic cell및 necrotic cell의 비율은 염분 별로는 26 psu구에서 가장 높게 나타났고, 4~6℃일 때 다른 실험구에 비해 유의하게 높았다. 이러한 결과들은 26 psu의 염분과 6℃ 이하의 수온에서는 참전복의 스트레스 반응이 증가하였으나, 30, 34 psu의 염분과 8, 10℃의 수온에서는 대조구와 차이가 없어, 참전복의 수송을 위한 적정 수온 및 염분 조건은 8~10℃, 30~34 psu인 것으로 나타난다.

• Journal of Microbiology and Biotechnology
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• 제17권8호
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• pp.1330-1337
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• 2007

To better understand the gene expression of the cold-adapted polar diatom, we conducted a survey of the Chaetoceros neogracile transcriptome by cDNA sequencing and expression of interested cDNAs from the Antarctic diatom. A non-normalized cDNA library was constructed from the C. neogracile, and a total of 2,500 cDNAs were sequenced to generate 1,881 high-quality expressed sequence tags (ESTs) (accession numbers EL620615-EL622495). Based on their clustering, we identified 154 unique clusters comprising 342 ESTs. The remaining 1,540 ESTs did not cluster. The number of unique genes identified in the data set is thus estimated to be 1,694. Taking advantage of various tools and databases, putative functions were assigned to 939 (55.4%) of these genes. Of the remaining 540 (31.9%) unknown sequences, 215 (12.7%) appeared to be C. neogracile-specific since they lacked any significant sequence similarity to any sequence available in the public databases. C. neogracile consisted of a relatively high percentage of genes involved in metabolism, genetic information processing, cellular processes, defense or stress resistance, photosynthesis, structure, and signal transduction. From the ESTs, the expression of these putative C. neogracile genes was investigated: fucoxanthin chlorophyll (chl) a,c-binding protein (FCP), ascorbate peroxidase (ASP), and heat-shock protein 90 (HSP90). The abundance of ASP and HSP90 changed substantially in response to different culture conditions, indicating the possible regulation of these genes in C. neogracile.

• 생태와환경
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• 제41권4호
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• pp.530-540
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• 2008

The temporal and spatial variations of size-structured phytoplankton dynamics in Youngsan Lake were investigated to explore potential mechanims controlling the dynamics in the Youngsan Lake. Field data were collected monthly from February to October, 2003 at 6 stations along the axis of Youngsan Lake. In this study, phytoplankton (chlorophyll $\alpha$) were categorized into three size classes: micro-size ($>20{\mu}m$), nano-size ($2{\sim}20{\mu}m$) and pico-size ($<20{\mu}m$). Water temperature, light attenuation coefficients, PAR (photosynthetically active radiation) and suspended solids were measured to analyze relationship between physical-chemical properties and size structure of phytoplankton. Phytoplankton blooms developed during March, July and October in the upper region of the main stem whereas small-scaled spring bloom was observed in the lower region. The scales of phytoplankton blooms were higher in the upper regions than the lower region and blooms were predominated by micro-size class in upper region but predominated by nano-size class in lower region. Growth of size-structured phytoplankton appeared to be controlled by rather light availability than temperature-dependant metabolisms in the system. Phytoplankton growth may be also supported by ambient nutrients available in the water column from analyses of chlorophyll $\alpha$ vs. nutrient concentrations including nitrite+nitrate and orthophosphate. Growth of nano-sized phytoplankton alone appeared to be supported by orthophosphate as well as nitrite+nitrate indicating that response of phytoplankton to nutrient inputs may be size-dependent.

• 한국전산구조공학회논문집
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• 제28권3호
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• pp.309-316
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• 2015

상태 기반 페리다이나믹 모델은 일반적인 재료 구성 모델을 구현할 수 있고 비국부 영역 내에서 연결된 모든 결합의 변형을 통해 각 절점의 재료 응답이 결정되기 때문에 체적 및 전단 변형을 모두 표현할 수 있다. 따라서 상태 기반 모델은 복잡한 동적 취성 파괴 현상(분기균열, 2차 균열, 계단균열, 균열 유착 등)을 해석하는데 유용하다. 본 논문에서는 평면응력 탄성체에 대해 2차원 상태 기반 페리다이나믹 모델을 적용하고 에너지해방율과 페리다이나믹 에너지 포텐셜로부터 손상 모델을 구성하였다. 페리다이나믹 파괴 해석 모델을 통해 취성 유리 재료에 대해 균열 면에 평행한 압축 응력파가 균열 분기 패턴에 미치는 영향에 대해 조사하였다. 실험을 통해 관찰된 동적 균열 진전 및 분기 패턴에 대한 주요 특성들이 페리다이나믹 해석을 통해 확인되었다. 또한 강한 인장 하중 하의 계단균열과 이차균열 등이 상태 기반 페리다이나믹 시뮬레이션을 통해 잘 모사가 되는 것을 확인할 수 있었다.

• 한국전산구조공학회논문집
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• 제31권3호
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• pp.133-140
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• 2018

본 논문은 $Ni-A{\ell}_2O_3$로 구성된 금속-세라믹 이종 입자복합재의 2차원 미세구조(microstructure) 생성과 미세구조 스케일(scale)에 따라 정의되는 계층적 모델들의 역학적 특성 분석에 관한 내용이다. 이종 입자복합재의 미세구조는 수학적인 MDF(random morphology description functions) 모델링기법을 복합재의 2차원 RVE(representative volume element) 영역에 적용하여 생성하였다. 그리고 미세구조 생성에 필요한 가우스 함수들의 개수에 따라 미세구조의 계층적 모델을 정의하였다. 한편 임의 미세구조 내 금속과 세라믹 입자가 차지하는 체적분율(volume fraction)은 RMDF 함수의 레벨을 조정함으로서 설정하였다. RMDF기법에 의한 미세구조들은 가우스 함수들의 개수가 일정할지라도 랜덤하게 생성된다. 이렇게 랜덤하게 생성되는 미세구조들을 2차원 보(beam) 모델에 적용하여 미세구조의 스케일에 따른 수직응력과 전단응력의 계층적 변동을 수치 해석적으로 고찰하였다. 또한, 균열해석을 통해 RMDF의 랜덤성과 가우스 함수들의 개수가 균열선단에서의 응력값에 미치는 영향을 고찰하였다.

• 한국해양환경ㆍ에너지학회지
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• 제20권2호
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• pp.91-99
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• 2017

본 연구에서는 몰수형 진자판을 이용한 파력발전장치의 성능 향상을 위한 파라메트릭 해석을 수행하였다. 선형포텐셜 이론에 기반을 둔 고유함수전개법을 사용하여 파기진 모멘트와 동유체 모멘트를 구하고, 파랑중 진자판의 회전운동 변위와 시간평균 추출파워를 구하였다. 이때 추출파워의 최대값을 주는 최적의 PTO감쇠계수를 제시하였다. 회전 운동하는 진자판으로부터 얻는 추출파워의 최대값은 시스템의 공진주파수에서 일어나며 진자판의 높이와 두께가 증가할수록 최대값은 증가하고 공진폭이 확장된다. 진자판 끝단에 설치된 계류로프는 부하상태에서 복원모멘트를 높이고 설치해역의 파랑과 공진이 유발하는데 활용된다. 천수역에 적합한 몰수형 진자판을 이용한 파력발전장치는 에너지 추출과 동시에 파를 차단하는 방파제의 기능을 동시에 지니고 있다.

• ALGAE
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• 제29권4호
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• pp.333-341
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• 2014

In this study, four compounds isolated from the red alga Laurencia snackeyi were evaluated for their potential anti-inflammatory effect in lipopolysaccharide (LPS)-stimulated RAW 264.7 macrophages. These compounds were tested for their inhibitory effects on nitric oxide (NO) production in LPS-stimulated RAW 264.7 cells. Since $5{\beta}$-hydroxypalisadin B showed the best activity it was further tested for the production of prostaglandin-$E_2$ ($PGE_2$), expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2), the release of pro-inflammatory cytokines tumor necrotic factor-alpha (TNF-${\alpha}$), interleukin-$1{\beta}$ (IL-$1{\beta}$), and interleukin-6 (IL-6). $5{\beta}$-Hydroxypalisadin B significantly reduced the $PGE_2$ release and suppressed the iNOS and COX-2 expression in LPS-stimulated RAW 264.7 cells. It also significantly reduced the release of pro-inflammatory cytokines TNF-${\alpha}$, IL-$1{\beta}$, and IL-6. These findings provide the first evidence of anti-inflammatory potential of $5{\beta}$-hydroxypalisadin B isolated from the red alga L. snackeyi and hence, it could be exploited as an active ingredient in pharmaceutical, nutraceutical and functional food applications.

• 수산경영론집
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• 제22권2호
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• pp.53-74
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• 1991

Interest on ocean environment has increased with the development of industrialized activities. Public marine resorces are defined broadly to include fish stocks, beaches, marine waters, recreational fishing, biota, waterfowls, shorebirds, seabirds and marine mammals But, it is not easy to analyze compensation for injury to publicly owned marine resources because the claimants do not exist clearly and the economic methodology of damage on public goods is not developed fully. This paper introduces basic idea of welfare economic theory and environmental legislation to the research question : How the economics and law can be applied to the case of damage on publicly owned marine resource. The paper discusses the concepts of willingness to pay (WTP) and willingness to accept (WTA). It is accepted generally that WTA is correct concept of welfare change in the case of damaged public goods. Four methods (compensating variation, equivalent variation, compensating surplus, equivalent surplus of measuring welfare changes are compared. Compensating variation(CV) is the best measure of welfare changes are compared. Compensating variation(CV) is the best measure of welfare changes caused by environmental damage. Vartia (1983) showed CV could be measured from the ordinary demand function using the differential equations. This paper also provides an overview of the emerging U.S. and Korea legal system for compensation for natural resource damages, with particular emphasis on U.S. legal system under Comprehensive Environmen-tal Response Compensation and Liability Act (CERCLA). These regulations are to include two different types of standardized procedures for assessing natural resources injury : Type A or simplified assessment techniques for small releases ; and Type B protocols that would include detailed and extensive assessment methodologies for major releases. Type A procedures are specified by Natural Resources Damage Assessment Model for Coastal and Marine Environment (NRDAM/CME) of the U.S. CERCLA provides a legal 'legitimization for the use of economic-based nonmarket valuation in the courts and have introduced appropriate and accurate nonmarket valuation methods based on willingness to-pay for damage assessment. By briefly reviewing economic theory and environmental legislation, we hope to help provide a better understanding of the compensation process and the economics of publicly owned marine resources in the U.S. and to integrate the economics and law of natural resources valuation into a single comprehensive package in Korea.

• 대한조선학회논문집
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• 제46권5호
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• pp.488-497
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• 2009

The freak wave, also known as New-Year-Wave in the north Atlantic, is relatively large and spontaneous ocean surface wave that can sink even large ships and destroy maritime structures. To understand oceanic conditions that develop freak waves, we simulated and generated two versions of scale-downed waves (1:64 and 1:42) in a numerical wave tank and compared the results with the experiment in wave flume. Both of the breaking and non-breaking waves were generated in the simulation. The numerical simulation was implemented based on the finite volume method and a genetic optimization algorithm. Random values were assigned as the initial values for the parameter in the control function, which produced signals representing the motion of wave-maker. The same signal obtained from the optimization process was used for both of the simulation and the experiment. By varying the object function and restrictions of the simulation, a best profile of design wave was selected based on the characteristics, height and period of simulated waves. Results showed that the simulation and experiment with the scale of 1:42 agreed better with freak waves in the natural condition. The presented simulation method will contribute to saving the time and cost for conducting subsequent response analyses of motion under freak waves in the course of the model test for ship and maritime structure.

• 한국환경농학회지
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• 제33권4호
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• pp.314-320
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• 2014

BACKGROUND: Run off from agricultural sites contaminates water bodies with nitrogen which is toxic and causes eutrophication when excessively accumulated. Hence, the interest in monitoring nitrogen toxicity in aquatic environment has been continuously increasing. METHODS AND RESULTS: To detect a real time toxicity of various nitrogen compounds, we applied biomonitoring method (biosensor) based on sulfur-oxidizing bacteria (SOB). The toxicity biomonitoring test was conducted in semi-continuous mode in a reactor filled with sulfur particles (2~4 mm diameter) under aerobic condition. Relative toxicity was simply determined by measuring the change in electrical conductivity (EC). Various nitrogenous compounds at different concentrations were evaluated as a potential toxic substance. Nitrite was found to be very toxic to SOB with a 90% inhibition even when the concentration as low as 3 mg/L. However, nitrate and ammonia have any inhibitory effect on SOB's activity. CONCLUSION: The biosensor based on SOB responded sensitively to nitrite even at substantially low concentrations. Therefore, it can be used as a reliable biological alarm system for rapid detection of contaminants due to its simplicity and sensitive nature.