• 한국해양바이오학회지
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• 제2권3호
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• pp.142-148
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• 2007

Agar로부터 oligosaccharides를 제조하기 위하여 효소 (agarase)를 이용한 분해법이 시도되면서 agarase의 균주의 분리 및 유전자에 대한 많은 연구가 수행되고 있다. 본 연구에서는 해양으로부터 agarase를 생성하는 균주를 분리 동정하고 균주의 특성을 조사하였다. 분리된 균주는 AS-3균주는 16S rDNA 염기서열분석에 의하여 Algibacter lectus AS-3로 동정되었다. 정제된 효소의 최적 활성 조건 및 agar 분해산물의 항산화활성을 조사하였다. 분리된 균주의 최적배양조건은 marine broth 2216에서 온도 $27^{\circ}C$, pH 7일 때 가장 균주의 생육이 높았다. Agarase 효소는 salt 침전, ion exchange와 gel filtration chromatography에 의해 9.6 units/mg으로 6.9배 정제되었다. 최적 효소활성은 온도 $40{\sim}50^{\circ}C$, pH 7일 때 나타났다. Agar 첨가한 배지에 agar 분해균을 접종한 후 분해산물의 시간에 따른 항산화활성은 12시간 배양 후 62%의 가장 높은 전자소거능 (EDA)을 나타내었다.

• 한국발생생물학회지:발생과생식
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• 제16권3호
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• pp.205-217
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• 2012

The ovarian cycle, the biological minimum size, and artificial spawning frequency by artificial spawning induction of the female hard clam, Meretrix petechialis, were investigated by histological observations and morphometric data. The ovarian cycle of this species can be classified into five successive stages: early active stage, late active stage, ripe stage, partially spawned stage, and spent/inactive stage. The spawning period was from June to September, and the main spawning occurred between July and August when the seawater temperature exceeds over $20^{\circ}C$. The biological minimum size (shell length at 50% of first sexual maturity) in females were 40.39 mm in shell length (considered to be two years of age), and all clams over 50.1 mm in shell length sexually matured. In this study, the mean number of the spawned eggs by spawning induction increased with the increase of size (shell length) classes. In case of artificial spawning induction for the clams > 40.39 mm, the number of spawned eggs from the clams of a sized class was gradually decreased with the increase of the number of the spawning frequencies (the first, second, and third spawning). In the experiments of artificial spawning induction during the spawning season, the interval of each spawning of this species was estimated to be 15-18 days (approximately 17 days).

• 한국패류학회지
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• 제29권4호
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• pp.313-323
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• 2013

Gonad development, the reproductive cycle, first sexual maturty and size at 50% of group sexual maturity (the biological minimum size) of Gomphina (Macridiscus) veneriformis were investigated for clams collected from the coastal waters of Donghae City, the East Sea of Korea by histological, and morphometric analysis. Monthly variations of the gonad index showed a pattern similar to that of the reproductive cycle. The reproductive cycle with the gonad developmental stages in female and male G. (M.) veneriformis can be classified into five successive stages: early active stage (December to March), late active stage (March to June), ripe stage (June to July), partially spawned stage (June to August), and spent / inactive stage (September to December). The spawning period continued from June to August, with a peak between July and August when the seawater temperature exceeds $20^{\circ}C$. The percentages of first sexual maturities of female and male clams ranging from 25.1 to 30.0 mm were 56.3% in females and 61.1% in males, and for clams over 30.1 mm shell length, it was 100%. Shell lengths at 50% of group sexual maturity (biological minimum size, $RM_{50}$) were 27.71 mm in females and 26.31 mm in males. Because harvesting clams < 26.31 mm in shell length could potentially cause a drastic reduction in recruitment, a measure indicating a prohibitory fishing size should be taken for adequate fisheries management.

• 한국산학기술학회논문지
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• 제21권6호
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• pp.545-551
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• 2020

이 연구는 함정 건조 중 국외도입된 물분사 추진기 임펠러 전체에 표면 점식이 확인되어 이에 대한 원인규명을 위하여 수행하였다. 물분사 추진기 임펠러의 재질은 듀플렉스 2205로 일반적인 스테인리스강인 316l 및 317L보다 부식 및 공식에 대한 저항성이 우수하며 높은 기계적 강도를 가지고 있어 각종 해양 구조물 및 해수 담수화 설비에 사용되는 재질이다. 물분사 추진기 임펠러에 표면 점식에 대한 원인분석을 위해 주사전자현미경 관찰 및 분자생태학적 분석 결과를 통해 다음과 같은 결론을 얻었다. 첫 번째로 주사전자현미경을 통하여 표면 점식이 일어난 부위에서 "S" 성분을 발견할 수 있었고, 두 번째로 분자생태학적 연구결과 부식된 물분사 추진기 임펠러에서 채취한 샘플에 "dsrAB" 유전자가 검출되어, 임펠러 부식은 황산염 환원균에 의한 것으로 판단할 수 있었다. 향후 황산염 환원균에 의한 제품의 손상을 방지하기 위해선 함정 운항 전, 후에 황산염 환원균이 활동하기 어려운 환경인 65℃ 이상의 고온처리 실시, pH5이하 또는 pH9이상 유지, 선체와 추진기의 절연을 통한 과잉전자 생성 방지 등 예방적 관리가 필요하다.

• 한국해양환경ㆍ에너지학회지
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• 제19권1호
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• pp.62-73
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• 2016

식생/모래기반 자연해빈에서의 파랑, 조석, 강우조건에 의한 지하수위 변동은 식생 환경과 밀접한 관련이 있으며 이는 식생 발달 및 지반 안정화에 크게 영향을 주는 요소이다. 본 연구는 낙동강 하구역의 사주섬 중 최서측에 위치하는 진우도를 대상으로 실험구를 구축한 후 해안선의 법선 방향으로 관측점 5곳을 선정하여 2012년 3월부터 2014년 9월까지(약 799일간) 관측된 수온, 전기전도도, 압력값을 이용하여 지하수위 변동해석을 하였다. 지하수위의 수온, 염분, 수위 변동과 조위, 파랑, 강수량 등의 외력조건과의 시계열 분석 및 상관분석을 통하여, 소상대 정점에서는 파랑 및 조위의 영향, 식생 및 모래지반 정점에서는 강수량 및 조위의 영향을 크게 받음을 알 수 있었다. 고파랑 내습시 관측점간의 지하수위 및 전기전도도의 공간적 거동을 살펴본 결과 Sand dune 및 Vegetation zone이 시작되는 인근에서 담수층과 해수층의 천이 영역(Transition zone)이 존재하였다.

• 한국발생생물학회지:발생과생식
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• 제20권3호
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• pp.187-196
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• 2016

The objective of the current study was to determine acute plasma stress responses in two size groups of juvenile Epinephelus akaara (average body weight: $8.4{\pm}2.1$ and $3.3{\pm}0.6g$; 150 and 120 days after hatch, respectively) exposed to abrupt salinity drops (from 34 practical salinity unit, PSU seawater to 18, 10 PSU (experiment 1) or 26, 18, 10 PSU (experiment 2), respectively). Plasma glucose, glutamic oxalate transaminase, glutamic pyruvate transaminase, red blood cell counts, and gill histology were determined during 72 h exposure. Significantly increased plasma glucose, glutamic oxalate transaminase levels, and red blood cell counts were observed in fish exposed to 18 or 10 PSU. Histological changes, such as hyperplasia and lifting of epithelium in the gill secondary lamellae, were also observed in fish exposed to 18 or 10 PSU at 72 h post-drop. E. akaara exposed to sudden salinity drops to 18 or 10 PSU still seems to undergo the primary adjustment phase before fish reaches a new homeostasis, whereas fish exposed to 26 PSU seems to mount osmotic changes. Therefore, the no observed adverse effect levels for 72 h acute salinity challenge was 26 PSU in our study, and salinity drop to 18 PSU and below can possibly cause acute adverse effect, in which fish could be vulnerable to additional stresses such as a temperature changes or handling stress.

• 한국수소및신에너지학회논문집
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• 제28권4호
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• pp.401-406
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• 2017

When Liquified Natural Gas (LNG) is vaporized into NG for industrial and household usage, tremendous cold energy was transferred from LNG to seawater during phase-changing process. This heat exchanger loop is not only a waste of huge cold energy, but will cause thermal pollution to the coastal fishery area also when cold water was re-injected into the sea. In this study, an innovation design has been performed to reclaim the cold energy for -35 to $62^{\circ}C$ refrigerated warehouse. Conventionally, this was done by installing mechanical refrigeration systems, necessitating tremendous electrical power to drive temperature. A closed loop LNG heat exchangers in series was designed to replace the mechanical or vapor-compression refrigeration cycle by process simulator. The process simulation software of PRO II with provision has been used to simulate this process for various conditions, what to effect on cold energy and used energy for re-liquefaction and evaporation process. In addition, through analysis the effect of the change of LNG supply pressure on sensible and latent heat, optimum operational conditions was suggested for LNG cold energy warehouse.

• 수산해양기술연구
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• 제42권1호
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• pp.19-29
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• 2006

To investigate the fishery and fishing ground environment of red horsehead (Branchiostegus japonicus), the author analyzed the fishery data and examined the amount of catches and oceanic environment on the adjacent seas of Jeju island and East China Sea. It was turned out that the favourable season of the red horsehead fishery is the month from March to June, the main fishing ground is located in 60 mile radius from the position $32.5^{\circ}N,\;125.7^{\circ}E$. The bottom seawater temperature in fishing ground was shown between $l3^{\circ}C\;and\;16^{\circ}C$, the salinity was appeared between 33.5 and 34.0psu without the seasonal variation of the year. Concentrations of materials(e.g, $NO_3^-\;and\;NO_2^-$) in spring and summer time in main fishing ground were higher than any other seasons, but that of phospheric materials were lower than any other seasons. Concentrations of $chlorophyll\;-\;{\alpha}$ in the main fishing ground was the highest in spring and summer at the surface layer, but the vertical profile of the $chlorophyll\;-\;{\alpha}$ concentrations in all seasons were not variable at bottom layer. Mean density of zooplankton abundance according to the vertical structure was higher and much stable in summer and autumn than spring and winter.

• 한국수산과학회지
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• 제37권5호
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• pp.385-392
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• 2004

Gonadal development, gametogenesis, reproductive cycle, gonad index, and flesh weight rate of the murex shell (Ocenebra japonica) collected from the rocky intertidal zone of Buan-gun, Jeollabuk-do, Korea were investigated by means of histological method from January to December 2002. O. japonica had separate sexes, and was oviparous. The gonad was widely situated on the surface of the digestive gland located in the rear of the spiral flesh part in the shell. The male penis was located near the two tentacles. The ovary was composed of a number of oogenic follicles, and the testis was composed of several spermatogenic tubules. The size of ripe oocyte was approximately $140{\mu}m$ in diameter. The gonad index (GI) began to increase in March $(33.24{\pm}2.33)$ and reached the maximum in June $(47.77{\pm}1.90)$ Thereafter, the values decreased from July $(45.12{\pm}3.60)$ to October $(19.32{\pm}2.91)$. The flesh weight rate (FWR) began to increase in January $(25.93{\pm}1.32)$ and reached the maxium in May $(31.78{\pm}1.09)$ Thereafter, the values decreased from June $(31.50{\pm}0.66)$ to October $(24.09{\pm}1.60)$. The reproductive cycle could be classified into five successive stages: early active (October to April), late active (January to June), ripe (May to September), spawning (July to September) and recovery (September to February). The reproductive cycle was closely related to the seawater temperature.

• 한국환경과학회지
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• 제8권4호
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• pp.451-456
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• 1999

Microorganisms utilizing petroleum as substrate were screened from the seawater in Pusan coastal area. Among them, fifty strains utilized bunker-A oil as a sole carbon and energy source. Five of these fifty strains were selected to experiment this study. According to the taxonomic characteristics of its morphological, cultural and biochemical properties, the selected stains were named Pseudomonas sp. EL-12, Flavobacterium sp. EL-15, Acinetobacter sp. EL-18, Enterobacter sp. EL-27 and Micrococcus sp. EL-43, respectively. The optimal medium compositions and cultural conditions for assimilation of bunker-A oil by the selected strains were 1.5-2% bunker-A oil, 0.1% $NH_4NO_3$, 1-1.5% $MgSO_4$.$7H_2O$, 0.05-0.15% KCl, 0.1-0.15% $CaCl_2$.$2H_2O$, 2.5-3.5% NaCl, initial pH 8-9, temperature 3$0^{\circ}C$ and aeration, respectively. The utilization and degradation characteristics on the various hydrocarbons by the selected stains were showed that bunker oil, n-alkane and branched alkane compounds were highly activity than cyclic alkane and aromatic hydrocarbon compounds.