• KSII Transactions on Internet and Information Systems (TIIS)
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• 제11권11호
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• pp.5243-5263
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• 2017

Data center networks provide critical bandwidth for the continuous growth of cloud computing, multimedia storage, data analysis and other businesses. The problem of low link bandwidth utilization in data center network is gradually addressed in more hot fields. However, the current scheduling strategies applied in data center network do not adapt to the real-time dynamic change of the traffic in the network. Thus, they fail to distribute resources due to the lack of intelligent management. In this paper, we present an improved adaptive traffic scheduling strategy utilizing the simulated annealing genetic algorithm (SAGA). Inspired by the idea of software defined network, when a flow arrives, our strategy changes the bandwidth demand dynamically to filter out the flow. Then, SAGA distributes the path for the flow by considering the scheduling of the different pods as well as the same pod. It is implemented through software defined network technology. Simulation results show that the bisection bandwidth of our strategy is higher than state-of-the-art mechanisms.

• 대기
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• 제24권2호
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• pp.235-243
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• 2014

Sources of aviation turbulence vary through the seasons, especially in the East Asia including Korean peninsula, associated primarily with the changes in the jet/front system and convective activities. For this reason, a seasonal Korean aviation Turbulence Guidance (KTG) system (seasonal-KTG) is developed in the present study by using pilot reports (PIREPs) and analysis data of the operational Unified Model (UM) of the Korea Meteorological Administration (KMA) for two years between June 2011 and May 2013. Twenty best diagnostics of aviation turbulence in each season are selected by the method of probability of detection (POD) using the PIREPs and UM data. After calculating a weighting value of each selected diagnostics using their area under curve (AUC), the 20 best diagnostics are combined with the weighting scores into a single ensemble-averaged index by season. Compared with the current operational-KTG system that is based on the diagnostics applying all seasons, the performances of the seasonal-KTG system are better in all seasons, except in fall.

• 대한조선학회논문집
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• 제47권6호
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• pp.763-769
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• 2010

Thanks to the rapid advancement of computational power and development of numerical methods, Computational fluid dynamics techniques are being used widely for the prediction of ship resistance performance. In the present study, an automatic tool was developed to facilitate hull form modification, consequent mesh generation, and flow analysis for parametric study. It is a tedious job to go back and forth between geometry modification and mesh generation for every hull form variation. With the developed tool, users can make multiple hull form variation and their hull form performance prediction easily in a few simple steps. The verification of the developed tool was done by applying it to resistance performance parametric study of a generic POD propulsion cruise ship with different lengths of bow and stern. It is believed that the tool can be extended to more sophisticated hull form variation and help optimize the ship performance more efficiently.

• Journal of Microbiology and Biotechnology
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• 제29권1호
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• pp.59-65
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• 2019

Fusaricidin analogs, produced by Paenibacillus polymyxa, were tested for selective control of a major bloom-forming cyanobacterium, Microcystis sp. Fusaricidin (A and B mixtures) and four analogs were isolated from P. polymyxa E681 and investigated for their inhibition of cyanobacterial cell growth. Among the four fusaricidin analogs, fraction 915 Da (designated as Fus901) showed growth inhibition activity for Microcystis aeruginosa but not for Anabaena variabilis and Scenedesmus acutus. Microcystin concentration decreased up to 70% and its content per cell also decreased over 50% after 3 days. Fusaricidin exhibited growth inhibition against Gram-positive bacteria but Fus901 did not. Molecular weights of fusaricidin A and B were 883 Da and 897 Da, whereas that of Fus901 was 915 Da. Structure analysis by a ring-opening method revealed a linear form for Fus901. Expression of the pod gene related to oxidative stress was increased 2.1-fold by Fus901 and that of mcyD decreased up to 40%. These results indicate that Fus901 exerts oxidative stress against M. aeruginosa. Thus, Fus901 can be used as a selective cyanobactericide without disturbing the ecological system and could help in decreasing the microcystin concentration.

• Nuclear Engineering and Technology
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• 제55권6호
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• pp.1999-2010
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• 2023

Undesirable flapping motion of discs can cause the failure of swing check valves in nuclear passive safety systems. Time-resolved particle image velocimetry (PIV) was employed to investigate the flow characteristics around a free-to-rotate plate and the motion response, with the Reynolds numbers, based on the hydraulic diameter of the channel, from 1.32 × 10⁴ to 3.95 × 10⁴. Appreciable flapping motion (±3.52°) appeared at the Reynolds number of 2.6 × 10⁴ with the frequency of 5.08 Hz. In the low-Reynolds-number case, the plate showed negligible flapping. In the high-Reynolds-number case, the deflection angle increased with reduced flapping amplitude. The torque from the fluid determined the flapping amplitude. In the low-Reynolds-number case, Karman vortices were absent. With increasing Reynolds numbers, Karman vortices developed behind the plate with larger deflection angles. Strong interaction between the wake flow from the leading and trailing edge of the plate was observed. Based on power spectrum density (PSD) analysis, the vortex shedding frequency coincided with the flapping frequency, and the amplitude was positively correlated to the strength of the vortices. Proper orthogonal decomposition (POD) modes evince that, in the case of appreciable motion, coherent structures exhibited a larger spatial scale, enhancing the magnitude of the external torque on the plate.

• 한국추진공학회지
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• 제13권5호
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• pp.57-63
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• 2009

본 논문에서는 항공기 POD용 환경조절장치의 개발을 위한 모델링 및 시뮬레이션에 관한 연구를 수행하였다. 먼저, 시스템 요구성능을 분석하여 ACM 방식의 환경조절장치를 구성하고 성능모사를 위한 모델링을 수행하였다. 다음으로 각 구성품의 개념설계를 위해 주요구성품의 성능변화에 따른 민감도를 분석하고 시스템 요구성능을 만족하는 설계점 성능을 결정하였다. 다양한 비행환경에서의 탈설계 성능 모사를 통해 전체 운용영역에서의 개념설계 타당성을 검토하고 천이 성능해석을 통해 동적 거동특성을 분석하였다.

• 한국작물학회지
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• 제42권2호
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• pp.202-213
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• 1997

본 시험은 최근 수요가 증가하고 있는 검정콩에 대한 특성을 조사하고 우량계통 육성을 위한 기초자료를 얻고자 수집한 검정콩 28개 재래종에 대하여 주성분 분석에 의한 품종군 분류와 품종군별 생산적 검정을 한 결과를 요약하면 다음과 같다. 1. 수집 검정콩의 결실일수는 58∼82일, 생육일수는 117∼148일로 변이폭이 컸으며, 결실일수와 생육일수가 길어질수록 100립중이 무거워지는 경향이었다. 2. 만숙군에서 비율이 낮았고, 생육일수는 개화일수, 결실일수, 100립중, 경장, 분지수 등과는 각각 정의 상관을 나타내었다. 3. 주성분분석 결과 상위 2개의 주성분만으로도 전체 변동의 76.5％를 표시할 수 있었으며, 품종간 유연도를 나타내는 single link cluster 분석으로 28개 수집재래종을 9개의 품종군으로 분류할 수 있었다. 4. 품종군 분류에 의해 다협, 소립, 다수성인 남해 -2, 함양-1을 나물콩용으로 선발하였다.

• 대기
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• 제27권2호
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• pp.189-197
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• 2017

Progressing from weather forecasts and warnings to multi-hazard impact-based forecast and warning services represents a paradigm shift in service delivery. Urban flooding is a typical meteorological disaster. This study proposes support plan for urban flooding impact-based forecast by providing inundation risk matrix. To achieve this goal, we first configured storm sewer management model (SWMM) to analyze 1D pipe networks and then grid based inundation analysis model (GIAM) to analyze 2D inundation depth over the Gangnam drainage area with $7.4km^2$. The accuracy of the simulated inundation results for heavy rainfall in 2010 and 2011 are 0.61 and 0.57 in POD index, respectively. 20 inundation scenarios responding on rainfall scenarios with 10~200 mm interval are produced for 60 and 120 minutes of rainfall duration. When the inundation damage thresholds are defined as pre-occurrence stage, occurrence stage to $0.01km^2$, 0.01 to $0.1km^2$, and $0.1km^2$ or more in area with a depth of 0.5 m or more, rainfall thresholds responding on each inundation damage threshold results in: 0 to 20 mm, 20 to 50 mm, 50 to 80 mm, and 80 mm or more in the rainfall duration 60 minutes and 0 to 30 mm, 30 to 70 mm, 70 to 110 mm, and 110 mm or more in the rainfall duration 120 minutes. Rainfall thresholds as a trigger of urban inundation damage can be used to form an inundation risk matrix. It is expected to be used for urban flood impact forecasting.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2006년도 International Symposium on GPS/GNSS Vol.2
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• pp.267-270
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• 2006

The International GNSS Service (IGS) has managed the global GNSS network and provided the highest quality GNSS data and products, which are GPS ephemerides, clock information and Earth orientation parameter, as the standard for GNSS. An important part of its works is to provide the precise orbits of GPS satellites. GPS satellites send their orbit information (broadcast ephemerides) to users and their accuracies are approximately 1.6 meters level, but those accuracies are not sufficient for the high precise applications which require millimeters precision. The current accuracies of the IGS final orbits are within 5 centimeters level and they are used for Earth science, meteorology, space science, and they are made by the IGS analysis centers and combined by the IGS analysis center coordinator. The techniques making the products are very difficult and require the high technology. The Korea Astronomy and Space Science Institute (KASI) studies to make the IGS products. In this study, we developed our own processing strategy and made GPS ephemerides using Bernese GPS software Ver. 5.0. We used the broadcast ephemerides as the initial orbits and processed the globally distributed 150 IGS stations. The result shows about 6 to 8 centimeters in root-mean-squares related to IGS final orbits in each day during a week. We expect that this study can contribute to secure our own high technology.

• Journal of Chest Surgery
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• 제18권4호
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• pp.849-854
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• 1985

We have experienced 50 cases of mediastinal tumors and cysts from March, 1979 to August, 1985 at Kyung Hee University Hospital. The results of this cases analysis were as followings; 1. Of all 50 mediastinal tumors and cysts, 26 patients were male and 24 patients were female. There was no sex preference. The age distribution was from 27 months to 64 years, and mean age was 33.5 years old, and also no age preference. 2. The most common mediastinal tumor was benign cysts [12 cases], which comprise 24% of all mediastinal tumors and cysts. The second common mediastinal tumor was teratoma [9 cases-18%], and followed by thymic tumors and tuberculous granuloma [7 cases-14% each], neurogenic tumors [5 cases-10%], and other tumors [10 cases-20%]. 3. The anterior mediastinum was most common tumor location, and followed by middle, superior, and posterior. 4. All 9 teratomas were developed at anterior mediastinum, and 4 of 5 neurogenic tumors were developed at posterior mediastinum. Thymomas were developed at anterior and superior mediastinum. The bronchogenic cysts had no predilection of location. 5. The most common chief complaint at admission was chest pain or discomfort [23 cases-46%], and followed by cough with or without sputum, and exertional dyspnea. Asymptomatic patients were only 7 patients [24%]. 6. Of all 50 cases, 38 cases [76%] received radical tumor resection, 7 mediastinoscopic biopsy, 3 explo thoracotomy and biopsy, and 1 neck mass biopsy. 7. There were 2 hospital deaths, one of which was a patient who suffered malignant thymoma and Myasthenia Gravis. The patient received radical tumor excision, but died at 7th POD. The other patient was a patient with malignant transformation of the benign cystic teratoma. The operative mortality was 4%.