• 대한교통학회지
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• 제26권5호
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• pp.117-127
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• 2008

1978년 미국 내 항공시장의 규제완화와 함께 항공은 허브-앤-스포크 시스템(hub-and-spoke system)의 형태로 재구성되었다. 항공의 확장성을 중점적으로 고려할 때, 허브-앤-스포크의 활용은 여객의 환승이나 화물의 환적에 있어서 어느 정도의 이점이 존재한다는 것이 일반적인 견해이다. 또한 국가 차원으로 볼 때, 허브-앤-스포크를 통해 공항의 활성화 및 노선에 따른 밀도의 경제를 실현하도록 허브공항을 개발하는 정책적 지원의 동기가 될 수도 있다. 기존 선행연구들은 대다수 항공여객에 대한 연구들로 집중되어 왔으나 항공환적화물에 대한 연구는 그 수가 상대적으로 적게 나타났다. 이에 본 연구에서는 인천국제공항을 대상으로 하여 항공화물의 환적연계성에 대한 분석을 통해 허브-앤-스포크 상에서 과연 허브공항으로서의 기능과 성과를 수행하고 있는지를 측정코자 하였다. 이를 위한 연구의 범위는 인천국제공항을 통해 환적 되는 항공화물을 대상으로 하며, 개설 가능한 환적노선인 직항연결 및 우회연결(Direct and Indirect Connection)로 한정하였다. 인천국제공항을 기반으로 한 항공화물의 환적연계성을 분석하기 위해 인천국제공항과 연결된 공항들의 노선 수나 연결시간 등을 기준으로 하여 직항연결과 우회연결의 품질을 평가하는 방식으로 취하였다. 이를 위해 공항의 웨이브-시스템 구조를 분석하여 활용하는 NETSCAN 모델을 적용하였다.

• Journal of Astronomy and Space Sciences
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• 제19권4호
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• pp.273-282
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• 2002

과학위성 1호의 주탑재체인 원자외선 분광기의 검출기 전자부에 대한 특성을 분석하였다. FIMS (Far-ultraviolet Imaging Spectrograph)는 교차 지연선 양극을 가진 MCP(micro-channel plate)를 사용하여 입사된 원자외선 광자의 위치를 검출한다. MCP에 입사하는 광자는 MCP을 통해 전자형태로 변환되고 증폭된다. 증폭된 전하운의 중심은 양분되어 연결된 지연선을 통해 양단으로 나가게 되고, 지연선의 양단에서 전하운의 도착시간 차이를 구하여 입사된 광자의 위치를 판독한다. FIMS의 경우 2개의 MCP 검출기를 갖고 있으며, 각각 25mm$\times$25mm의 유효 크기를 갖고있다. 또 신호처리계는 1채널의 신호처리 회로계를 통해 2개의 검출기에 대한 영상검출이 가능하도록 함으로써 신호처리계의 복잡성을 피하고 아울러 전력과 무게 비용을 줄였다. 이 시스템을 통해 높은 시간 및 공간 분해능(<$35{\times}75$ps FWHM)을 얻었으며, 6W 이하의 저전력 시스템을 구현하였다.

• International Journal of Aeronautical and Space Sciences
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• 제17권4호
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• pp.518-525
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• 2016

This paper presents the characteristics of non-fundamental multi-mode combustion instability and the effects of high-harmonic components on the Rayleigh criterion. Phenomenological observations of multi-harmonic-mode dynamic pressure waves regarding the intensity of harmonic components and the source of wave distortion have been explained by introducing examples of second- and third-order harmonics at various amplitudes. The amplitude and order of the harmonic components distorted the wave shapes, including the peak and the amplitude, of the dynamic pressure and heat release, and consequently the temporal Rayleigh index and its integrals. A cause-and-effect analysis was used to identify the root causes of the phase delay and the amplification of the Rayleigh index. From this analysis, the skewness of the dynamic pressure turned out to be a major source in determining whether multi-mode instability is driving or damping, as well as in optimizing the combustor design, such as the mixing length and the combustor length, to avoid unstable regions. The results can be used to minimize errors in predicting combustion instability in cases of high multi-mode combustion instability. In the future, the amount of research and the number of applications will increase because new fuels, such as fast-burning syngases, are prone to generating multi-mode instabilities.

• BMB Reports
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• 제39권1호
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• pp.37-45
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• 2006

Bulked segregant analysis (BSA) and AFLP were used for isolation of genomic sex determination markers in Penaeus monodon. A total of 256 primer combinations were tested against 6-10 bulked genomic DNA of P. monodon. Five and one candidate female- and male-specific AFLP fragments were identified. Female-specific fragments were cloned and further characterized. SCAR markers derived from FE10M9520, FE10M10725.1, FE10M10725.2 and FE14M16340 provided the positive amplification product in both male and female P. monodon. Further analysis of these markers using SSCP and genome walk analysis indicated that they were not sex-linked. In addition, sex-specific (or differential) expression markers in ovaries and testes of P. monodon were analyzed by RAP-PCR (150 primer combinations). Twenty-one and fourteen RAP-PCR fragments specifically/differentially expressed in ovaries and testes of P. monodon were successfully cloned and sequenced. Expression patterns of 25 transcripts were tested against the first stranded cDNA of ovaries and testes of 3-month-old and broodstock-sized P. monodon (N = 5 and N = 7 - 10 for females and N = 4 and N = 5 - 7 for males, respectively). Five (FI-4, FI-44, FIII-4, FIII-39 and FIII-58) and two (M457-A01 and MII-51) derived RAP-PCR markers revealed female- and male-specific expression patterns in P. monodon. Surprisingly, MII-5 originally found in testes showed a higher expression level in ovaries than did testes of juvenile shrimps but a temporal female-specific pattern in P. monodon adults.

• 천문학논총
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• 제14권1호
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• pp.39-45
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• 1999

We have carried out measurements of 1.2-1.6GHz radio interferences around Seoul Radio Astronomy Observatory located in the campus of Seoul National University. We received interference signals using a pyramidal horn antenna and measured its power using a spectrum analyzer with 1MHz resolution after $\~60dB$ amplification. In order to check the spatial characteristics, we made observations at every $30^{\circ}$ in azimuth at elevation of $30^{\circ}\;and\;60^{\circ}$. Also, in order to check the temporal characteristics, we repeated the all-sky observations five times at every six hours. The results may be summarized as follows: (1) There are strong $({\geq}-20dBm)$ interferences between 1.2 and 1.4GHz. Particularly strong interferences are observed at 1.271 and 1.281GHz, which have maximum powers of -0.34dBm and -0.56dBm, respectively. (2) The characteristics of the interferences do not depend strongly on directions, although the interferences are in general weak at high elevation and in east-west direction. (3) The interferences appear for a very short $(\leq0.01s)$ period of time, so that the average power is much smaller than the maximum power. Strong interferences with large $(\leq-49.0dBm)$ average power have been observed at 1.271, 1.281, 1.339, and 1.576GHz. At these frequencies, the interferences appear repeatedly with a period of $\leq0.1s$ By analyzing the observed power, we find that, for the strongest 1.271GHz interference, the average intensity is $-171dBW/m^2/Hz$ and that the maximum intensity is $-122dBW/m^2/Hz$. If this interference is delivered to the detector without any shielding, then its power would be much greater than the rms noise of a typical line spectrum. Therefore, it is important to shield all the parts of receiver carefully from radio interferences. Also, without appropriate shielding, the sensitivity of a receiver could be limited by the interference.

• Fisheries and Aquatic Sciences
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• 제21권3호
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• pp.5.1-5.8
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• 2018

Stimulator of interferon gene (STING) is induced by various inflammatory agents, such as lipopolysaccharide and microbial pathogens, including virus and bacteria. In this study, we obtained a full-length cDNA of a STING homolog from olive flounder using rapid amplification of cDNA ends PCR technique. The full-length cDNA of Paralichthys olivaceus STING (PoSTING) was 1442 bp in length and contained a 1209-bp open reading frame that translated into 402 amino acids. The theoretical molecular mass of the predicted protein sequence was 45.09 kDa. In the PoSTING protein, three transmembrane domains and the STING superfamily domain were identified as characteristic features. Quantitative real-time PCR revealed that PoSTING expressed in all the tissues analyzed, but showed the highest level in the spleen. Temporal expression analysis examined the significantly upregulated expression of PoSTING mRNA after viral hemorrhagic septicemia virus (VHSV) stimulation. In contrast, no significant changes in the PoSTING expression were detected in Edwardsiella tarda-challenged group compared to the un-injected control. The expression of P. olivaceus type I interferon (PoIFN-I) was also highly upregulated upon VHSV challenge. These results suggest that STING might be involved in the essential immune defense against viral infection together with the activation of IFN-I in olive flounder.

• Journal of Ecology and Environment
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• 제45권4호
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• pp.203-217
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• 2021

Background: Sea turtles, which are globally endangered species, have been stranded and found as bycatch on the Korean shore recently. More studies on sea turtles in Korea are necessary to aid their conservation. To investigate the spatio-temporal occurrence patterns of sea turtles on the Korean shore, we recorded sampling locations and dates, identified species and sexes and measured sizes (maximum curved carapace length; CCL) of collected sea turtles from the year 2014 to 2020. For an analysis of diets through stomach contents, we identified the morphology of the remaining food and extracted DNA, followed by amplification, cloning, and sequencing. Results: A total of 62 stranded or bycaught sea turtle samples were collected from the Korean shores during the study period. There were 36 loggerhead turtles, which were the dominant species, followed by 19 green turtles, three hawksbill turtles, two olive ridley turtles, and two leatherback turtles. The highest numbers were collected in the year 2017 and during summer among the seasons. In terms of locations, most sea turtles were collected from the East Sea, especially from Pohang. Comparing the sizes of collected sea turtles according to species, the average CCL of loggerhead turtles was 79.8 cm, of green turtles was 73.5 cm, and of the relatively large leatherback turtle species was 126.2 cm. In most species, the proportion of females was higher than that of males and juveniles, and was more than 70% across all the species. Food remains were morphologically identified from 19 stomachs, mainly at class level. Seaweeds were abundant in stomachs of green turtles, and Bivalvia was the most detected food item in loggerhead turtles. Based on DNA analysis, food items from a total of 26 stomachs were identified to the species or genus level. The gulfweed, Sargassum thunbergii, and the kelp species, Saccharina japonica, were frequently detected from the stomachs of green turtles and the jellyfish, Cyanea nozakii, the swimming crab, Portunus trituberculatus, and kelps had high frequencies of occurrences in loggerhead turtles. Conclusions: Our findings support those of previous studies suggesting that sea turtles are steadily appearing in the Korean sea. In addition, we verified that fish and seaweed, which inhabit the Korean sea, are frequently detected in the stomach of sea turtles. Accordingly, there is a possibility that sea turtles use the Korean sea as feeding grounds and habitats. These results can serve as basic data for the conservation of globally endangered sea turtles.