• Journal of the korean society of oceanography
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• 제31권4호
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• pp.196-206
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• 1996

Vertical profiles of the chlorophyll ${\alpha}$, phytoplankton abundance, nutrients and sigma-t were compared with the vertical distribution of phytoplankton species in conjunction with $^{14}$C primary production in the Southern Waters of the East Sea, Korea. In the upper mixed layer the water column was only weakly stratified and ambient nitrogenic nutrient concentrations were markedly depleted. Dissolved silicate seemed to be another limiting nutrient in the surface layer. The occupation of different water depths by several dominant diatom species was well explained by the degree of silicification of each cell and the silicate concentration of ambient seawater. Subsurface chlorophyll maxima were continuously observed in the lower parts of the euphotic layer and the depth coincided with nutricline, supporting our view that chlorophyll maximum was sustained partially by enhancement of in situ growth of phytoplankton and partially by increase of cellular chlorophyll content. The persistence of chlorophyll maximum layer was attributed to the physiological adaptation of the phytoplankters to low light intensities and to the utilization of regenerated nutrients. Integrated water column production of organic matter by photosynthesis appeared to be better related to phytoplankton cell division than to the cell growth in terms of biosynthesis of pigments and other intracellular components.

• Nutrition Research and Practice
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• 제1권4호
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• pp.260-265
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• 2007

Preservation methods on the physiological and brewing technical characters in bottom and top brewing yeast strains were investigated. The preserved yeasts were reactivated after 24 months storage and grown up to stationary phase. The samples of filter paper storage indicated a higher cell growth and viability during propagation than those of nitrogen and lyophilization storage independent on propagation temperature. In addition, the filter paper storage demonstrated a faster absorption of free amino nitrogen and a highest level of higher aliphatic alcohols production during propagation than other preservation methods, which can be attributed to intensive cell growth during propagation. Moreover, the filter paper storage showed a faster accumulation for glycogen and trehalose during propagation, whereas, in particular, lyophilization storage noted a longer adaptation time regarding synthesis of glycogen and trehalose with delayed cell growth. In beer analysis, the filter paper storage formed an increased higher aliphatic alcohols than control. In conclusion, the preservation of filter paper affected positively on yeast growth, viability and beer quality independent on propagation temperature. In addition, in this study, it was obtained that the HICF and Helm-test can be involved as rapid methods for determination of flocculation capacity.

• 한국음향학회지
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• 제14권5호
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• pp.51-57
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• 1995

본 논문에서는 청각 모델을 기초로 잡음에 강한 음성 특징 추출을 연구하였다. 청각모델은 basilar membrane 모델, 섬모세포(hair cell) 모델과 스펙트럼 출력단으로 구성하였다. Basilar membrane 모델은 음파의 진동에 따른 전달 특성을 묘사한 것으로 대역 통과 필터의 열로 나타난다. 섬모 세포 모델은 basilar membrane의 진동에 의한 신경 물질로의 변환을 나타낸다. 이것은 입력의 상대적인 값에 크게 반응하는 adaptation 기능을 이용하게 되며, 잡음 제거에 중요한 역할을 하게 된다. 스펙트럼 출력 단은 각 채널의 평균 firing rate를 이용하여 mean rate spectrum을 형성한다. 그리고 mean rate spectrum을 이용하여 특징 벡터를 추출하였다. 실험 결과는 청각 구조에 기초한 특징 추출이 다른 특징 추출 방법에 비해 잡음에서 더 향상된 성능을 가짐을 보였다.

• 한국물환경학회지
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• 제23권6호
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• pp.807-813
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• 2007

Settling velocity is one of major parameters determining algal biomass in water quality modeling. In this study, the settling velocity of phytoplankton was measured in reservoir and stream sites of the Nakdong River, Korea. Settling velocities of various phytoplankton species were determined by measuring algal cell biomass settled in a sedimentation cylinder. Mean settling velocities were $0.22m\;day^{-1}$ in reservoir sites and $0.33m\;day^{-1}$ in stream sites, which were relatively higher compared with other default values suggested by water quality models (e.g. $0.1m\;day^{-1}$ in CE-QUAL-W2). The lower settling velocity in reservoirs than in stream implies the adaptation of phytoplakton to low turbulence in lentic environments. Cyanobacteria showed lower settling velocity ($0.2m\;day^{-1}$) than diatoms ($0.3m\;day^{-1}$), and this phenomenon may have resulted from buoyancy mechanisms of cyanobacteria. Cell volume did not show a significant correlation with settling velocity in this study, implying that conformation factors of colonies or other factors had large effects on settling velocity of algal cells as well as cell size. The result of this study may suggest proper coefficients of settling velocity of phytoplankton in the calibration of water quality model.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제13권8호
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• pp.3821-3841
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• 2019

Cloud radio access networks (C-RANs) have been regarded in recent times as a promising concept in future 5G technologies where all DSP processors are moved into a central base band unit (BBU) pool in the cloud, and distributed remote radio heads (RRHs) compress and forward received radio signals from mobile users to the BBUs through radio links. In such dynamic environment, automatic decision-making approaches, such as artificial intelligence based deep reinforcement learning (DRL), become imperative in designing new solutions. In this paper, we propose a generic framework of autonomous cell activation and customized physical resource allocation schemes for energy consumption and QoS optimization in wireless networks. We formulate the problem as fractional power control with bandwidth adaptation and full power control and bandwidth allocation models and set up a Q-learning model to satisfy the QoS requirements of users and to achieve low energy consumption with the minimum number of active RRHs under varying traffic demand and network densities. Extensive simulations are conducted to show the effectiveness of our proposed solution compared to existing schemes.

• The Plant Pathology Journal
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• 제38권2호
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• pp.102-114
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• 2022

Pectobacterium carotovorum subsp. carotovorum (Pcc) is a gram-negative, broad host range bacterial pathogen which causes soft rot disease in potatoes as well as other vegetables worldwide. While Pectobacterium infection relies on the production of major cell wall degrading enzymes, other virulence factors and the mechanism of genetic adaptation of this pathogen is not yet clear. In the present study, we have performed an in-depth genome-wide characterization of Pcc strain ICMP5702 isolated from potato and compared it with other pathogenic bacteria from the Pectobacterium genus to identify key virulent determinants. The draft genome of Pcc ICMP5702 contains 4,774,457 bp with a G + C content of 51.90% and 4,520 open reading frames. Genome annotation revealed prominent genes encoding key virulence factors such as plant cell wall degrading enzymes, flagella-based motility, phage proteins, cell membrane structures, and secretion systems. Whereas, a majority of determinants were conserved among the Pectobacterium strains, few notable genes encoding AvrE-family type III secretion system effectors, pectate lyase and metalloprotease in addition to the CRISPR-Cas based adaptive immune system were uniquely represented. Overall, the information generated through this study will contribute to decipher the mechanism of infection and adaptive immunity in Pcc.

• 유기물자원화
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• 제14권3호
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• pp.117-125
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• 2006

원유에 오염된 토양으로부터 톨루엔을 분해할 수 있는 미생물을 분리하였으며 동정결과 Pseudomonas fluorescence였다. 이 미생물을 생물학적 톨루엔 처리공정에 사용하기 위해 온도, 톨루엔 농도, pH, 질소원 등의 환경영향이 분해에 미치는 영향에 대해서 연구를 하였다. 이 미생물의 최적 분해 온도는 $30^{\circ}C$였으며 이 때 최대 비성장속도와 최대 비소모속도는 각각 $0.76hr^{-1}$와 $0.36hr^{-1}$이었다. $10^{\circ}C$ 와 $40^{\circ}C$에서는 톨루엔을 분해하지 못하였으나 $30^{\circ}C$에 적응한 미생물은 $10^{\circ}C$에서 17시간 만에 100mg/L의 톨루엔을 완전히 분해하였고 $40^{\circ}C$ 에서는 30시간 동안 80% 정도 분해할 수 있었다. 본 미생물은 200mg/L 이상의 톨루엔은 분해할 수 없었으나 20mg/L의 낮은 농도의 톨루엔에 적응을 시킴으로써 300mg/L의 톨루엔까지 분해할 수 있었다. pH는 5.5~9.0 범위에서 분해 속도에 별다른 영향을 미치지 않는 것으로 나타났다. 암모늄 (${NH_4}^+$) 대신 질산염(${NO_3}^-$)을 사용했을 때 적응기가 2~10시간 정도 길어졌고 미생물 수율이 45% 정도 감소하였다. 그러나 적응기가 지난 후의 톨루엔 분해속도에서는 별 차이를 보이지 않았다. 본 연구에서 얻은 결과들은 향후 바이오필터 등의 생물학적 톨루엔 처리공정 개발에 유용하게 사용될 것으로 기대된다.

• Journal of Microbiology and Biotechnology
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• 제26권1호
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• pp.130-138
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• 2016

The use of antibiotics in aquaculture raises environmental and food safety concerns because chronic exposure of an aquatic ecosystem to antibiotics can result in the spread of antibiotic resistance, bioaccumulation of antibiotics in the organisms, and transfer of antibiotics to humans. In an attempt to overcome these problems, high-concentration red clay was applied as an alternative antibiotic against the following common fish pathogens: Aeromonas salmonicida, Vibrio alginolyticus, and Streptococcus equinus. The growth of A. salmonicida and V. alginolyticus was retarded by red clay, whereas that of S. equinus was promoted. Phase contrast and scanning electron microscopy analyses confirmed the attachment of red clay on cell surfaces, resulting in rapid gravitational removal and cell surface damage in both A. salmonicida and V. alginolyticus, but not in S. equinus. Different cell wall properties of grampositive species may explain the unharmed cell surface of S. equinus. Significant levels of oxidative stress were generated in only the former two species, whereas significant changes in membrane permeability were found only in S. equinus, probably because of its physiological adaptation. The bacterial communities in water samples from Oncorhynchus mykiss aquacultures supplemented with red clay showed similar structure and diversity as those from oxytetracycline-treated water. Taken together, the antibiotic effects of high concentrations of red clay in aquaculture can be attributed to gravitational removal, cell surface damage, and oxidative stress production, and suggest that red clay may be used as an alternative for antibiotics in aquaculture.

• Journal of Microbiology and Biotechnology
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• 제30권11호
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• pp.1785-1791
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• 2020

In a previous study, the sequential optimization and regulation of environmental parameters using the PhotoBiobox were demonstrated with high-throughput screening tests. In this study, we estimated changes in the biovolume-based composition of a polyculture built in vitro and composed of three algal strains: Chlorella sp., Scenedesmus sp., and Parachlorella sp. We performed this work using the PhotoBiobox under different temperatures (10-36℃) and light intensities (50-700 μmol m^-2 s^-1) in air and in 5% CO₂. In 5% CO₂, Chlorella sp. exhibited better adaptation to high temperatures than in air conditions. Pearson's correlation analysis showed that the composition of Parachlorella sp. was highly related to temperature whereas Chlorella sp. and Scenedesmus sp. showed negative correlations in both air and 5% CO₂. Furthermore, light intensity slightly affected the composition of Scenedesmus sp., whereas no significant effect was observed in other species. Based on these results, it is speculated that temperature is an important factor in influencing changes in algal polyculture community structure (PCS). These results further confirm that the PhotoBiobox is a convenient and available tool for performance of lab-scale experiments on PCS changes. The application of the PhotoBiobox in PCS studies will provide new insight into polyculture-based ecology.

• 한국어류학회지
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• 제26권4호
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• pp.281-287
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• 2014

수중과 육상의 이중적인 생활을 하는 남방짱뚱어 Scartelaos gigas (amphibious mudskipper)의 후각기관을 해부학과 조직학적으로 연구하였다. 그 결과 후각기관은 좌우 한 쌍이 존재하며 각 기관은 한 개의 가느다란 긴관 (an elongated canal)과 사비강과 누비강의 두 개의 비강 (ethmoidal and lacrimal nasal sacs)으로 구성되어 있었다. 각 관의 내벽에 발달한 감각 상피는 3~4개의 섬모를 가지는 감각 수용기 세포 (receptor cell), 지지세포 (supporting cell), 기저세포 (basal cell) 그리고 점액세포 (mucus cell)들로 구성되는 다세포성 구조로 이루어져 있었다. 반면에 비감각 상피는 감각기를 갖지 않는 주름진 표면만을 가지고 있었다. 또한 두 개의 비강은 상피 표면에 점액 방울 (mucin droplet)을 가지고 있었다. 따라서 남방짱뚱어의 이러한 후각기관의 특징은 생태적 습성과 서식처에 관련된 반수중 생활 (semi-aquatic life)에 적응한 특징으로 사료된다.