• Title/Summary/Keyword: Under Sampling

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A Global-Local Approach for Estimating the Internet's Threat Level

  • Kollias, Spyridon;Vlachos, Vasileios;Papanikolaou, Alexandros;Chatzimisios, Periklis;Ilioudis, Christos;Metaxiotis, Kostas
    • Journal of Communications and Networks
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    • v.16 no.4
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    • pp.407-414
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    • 2014
  • The Internet is a highly distributed and complex system consisting of billion devices and has become the field of various kinds of conflicts during the last two decades. As a matter of fact, various actors utilise the Internet for illicit purposes, such as for performing distributed denial of service attacks (DDoS) and for spreading various types of aggressive malware. Despite the fact that numerous services provide information regarding the threat level of the Internet, they are mostly based on information acquired by their sensors or on offline statistical sampling of various security applications (antivirus software, intrusion detection systems, etc.). This paper introduces proactive threat observatory system (PROTOS), an open-source early warning system that does not require a commercial license and is capable of estimating the threat level across the Internet. The proposed system utilises both a global and a local approach, and is thus able to determine whether a specific host is under an imminent threat, as well as to provide an estimation of the malicious activity across the Internet. Apart from these obvious advantages, PROTOS supports a large-scale installation and can be extended even further to improve the effectiveness by incorporating prediction and forecasting techniques.

Effects of Mowing and TIBA(Triiodobenzoic acid) on Dry Matter Production of Cultivated Zoysia japonica Community (잔디깍기와 TIBA 처리가 잔디 인공군락의 물질생산에 미치는 영향)

  • 진희성
    • Journal of Plant Biology
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    • v.30 no.2
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    • pp.135-149
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    • 1987
  • An experiment was made in order to analyze the growth characteristics and productivity of Zoysia japonica under control, mowing and TIBA treatment conditions at the experimental farm of Kyung Hee University. The field was planned by the split plot design method and each treatment was given to two plots (40$\times$40 and 100$\times$100 mm) and was replicated three times. Each plot was 9$m^2$ for Zoysia japonica. The sampling of each plot was taken once a week after sowing. In order to know the dry matter of total standing crops, each organ of plants was kept at 9$0^{\circ}C$ and weighed. Total leaf area of a plant was measured by drawing method. The author adopted the growth analysis of English School. Holocellulose analysis by sodium chlorite method was made. The increasing rate of LAI was high in all plots between 10th and 12th week after sowing and high growth rate of assimilatory organ was observed in low density area of TIBA plot. Between 10th and 12th week after sowing all the experimental plots showed high increasing rate of standing crop and in the process of growth each density area of TIBA plot recorded high increasing rate. In all the plots F/C ratio and RGR were high when the growth rate of assimilatory organ was increasing cosiderably, and the higher the planting density was, the higher F/C ratio was recorded. In all the plots NAR recorded maximum rate before the growth period to show a high increase of RGR. In the process of the growth TIBA plot showed high icnreasing rate of NAR. CGR showed high value in high density areas of all the plots and reached its maximum in the 13th week after sowing. Compared to the other experimental areas the low planting density areas of control plot and TIBA plot showed considerable earlier lignification indicating low Holocellulose content in the growth process.

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Compressed Sensing and the Applications of Wireless Communications (압축 감지 기술과 무선통신 응용)

  • Hwang, Dae-Sung;Kim, Dae-Sung;Choi, Jin-Ho;Ha, Jeong-Seok
    • Journal of the Institute of Electronics Engineers of Korea SP
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    • v.46 no.5
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    • pp.32-39
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    • 2009
  • Compressed Sensing is a method to sample analog signals at a rate under the Nyquist rate. With this scheme, it is possible to represent signals with a relatively smaller number of measurements than that of the conventional sampling method, and the original signals are reconstructed with high probability from the acquired measurements using the linear programming. Compressed sensing allows measurement time and/or the amount of ADC (analog-to-digital converter) resources for the signal acquisitions to be reduced. In this paper, we presents the backgrounds of the compressed sensing, a way to acquire measurements from an analog signal with a random basis, and the signal recovery method. Also we introduce applications of compressed sensing in wireless communications.

Pattern of Species Distribution along Environmental Variables in Two Different Forest Beat of Raghunandan Reserve Forest of Habiganj

  • Hosen, Md. Shahadat;Ahamed, Md. Saleh
    • Journal of Forest and Environmental Science
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    • v.33 no.4
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    • pp.257-269
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    • 2017
  • The study has piloted to find the Pattern of species distribution along environmental variables and disturbance in Raghunandan Reserve Forest. Shaltila and Shahapur beat of Raghunandan Hill Reserve Forest are situated in Chunarughat sub-district of Habiganj district between $24^{\circ}5^{\prime}-24^{\circ}10^{\prime}N$ and $91^{\circ}25^{\prime}-91^{\circ}30^{\prime}E$ under the Sylhet Forest Division. The Environmental variable and vegetation data were collected from 30 sample plots from each forest beat by using arbitrary sampling without preconceived bias. 51 species were found from Shaltila and 34 species found in Shahapur forest beat. Thus the dataset continued with total 85 species in 60 samples. To determine the relationships between tree species distribution and environmental variables, Canonical Correspondence Analysis (CCA) ordination method were performed separately for two forest beat. In CCA ordination, tree species showed significant variation along environmental gradients in terms of soil organic matter and disturbances (p<0.05) in the case of Shaltila forest. Potassium has a significant relationship with axis 1 and axis 2 in this forest. But Shahapur forest showed no significant relationship between species and environmental variables. Phosphorus has a significantly negative relationship with axis 2 in this forest. Disturbance played as a critical role of this forest thus influencing the distribution of species. The study showed that the distributions of tree species are strongly influenced by disturbance and organic matter in Shaltila and Shahapur forest beat showed no significant relationship between species and environmental variables. Future research should be included more environmental variables with larger study area that identify the most important environmental forces which will drive by species distribution findings in this forest.

Comparison of Temperament in Infancy between the normal Infants and Low-birth-weight (정상체중출생아와 저체중출생아의 영아기 기질 비교)

  • Bang, Kyung-Sook;June, Kyung-Ja
    • Korean Parent-Child Health Journal
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    • v.5 no.1
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    • pp.50-61
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    • 2002
  • The purpose of this study was to compare the temperamental differences between the normal infants and low-birth-weight infants. The subjects of this study were 70 mothers with normal infants and 62 mothers with the low-birth-weight. Convenient sampling was done at three regions. The infant temperament scale developed by Pridham & others (1994) was used. Data were analyzed by SPSS WIN program. The results were as follows; 1) There was a significant difference in total temperament score between the low-birth-weight infants and normal infants. The scores of the low-birth-weight infants were significantly lower than those of normal infants in the subscales of amenability and persistence, activity, and reactivity. In adaptability, there was no significant difference between two groups. 2) In both groups, there were no significant difference by socio-economic status of parents, delivery type, and birth order. But, in the case of low-birth-weight infants, the temperament score of infants over 6 months was significantly higher than that of infants under 6 months. 3) In the correlation analysis among subscales of the temperament, amenability and persistence, activity, and reactivity showed the significant relationship. But adaptability showed significant correlation only with the amenability and persistence. In conclusion, temperament score of low-birth-weight infants were significantly lower than that of normal infants. It was suggested that parenting education for low-birth-weight infants would be needed to understand and impact the positive infant temperament.

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Bioprospecting Endophytic Fungi and Their Metabolites from Medicinal Tree Aegle marmelos in Western Ghats, India

  • Mani, Vellingiri Manon;Soundari, Arockiamjeyasundar Parimala Gnana;Karthiyaini, Damodharan;Preethi, Kathirvel
    • Mycobiology
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    • v.43 no.3
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    • pp.303-310
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    • 2015
  • The increasing emergence of lead drugs for the resistance produced by the pathogenic strains and arrival of new diseases have initiated the need for searching novel metabolites with best anticancer and antimicrobial properties than the existing one. With this view, the investigation was conducted for the isolation, identification, and biological evaluation of potential endophytic fungi of Aegle marmelos, a medicinal tree used for more than three decades, for curing various disorders. A total of 169 endophytic fungal strains obtained from sampling and among those 67 were pigmented strains. Upon antagonistic screening, five endophytic fungal strains exhibited antagonistic potentiality by inhibiting the pathogens. These five potent strains were characterized at molecular level by sequencing the amplified internal transcribed spacer (ITS) 1 and ITS 4 regions of rDNA and they were grouped under order Pleosporales, Eurotiales, and Capnodiales. The metabolites from the respective strains were produced in fungal culturing media and extracted using polar solvents. Further, the extracts of five endophytes manifested antimicrobial activity against tested clinical pathogens and Alternaria alternata (FC39BY), Al. citrimacularis (FC8ABr), and Curvularia australiensis (FC2AP) exhibited significant antimicrobial profile against 9 of 12 tested pathogens, showing broad spectrum activity. The antioxidant levels of all the five endophytes revealed the highest activity at least concentrations, and major activity was unveiled by the members of order Pleosporales FC2AP and FC8ABr. This research explains the value of endophytic fungal extracts and its significance of antimicrobial and antioxidant properties.

Effect of Combined Rainfall Observation with Radar and Rain Gauge (강우 레이더와 지상 우량계의 통합관측효과)

  • Yoo, Chul-Sang;Kim, Kyoung-Jun
    • Journal of Korea Water Resources Association
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    • v.40 no.11
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    • pp.841-849
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    • 2007
  • This study evaluated the effect of combined rainfall observation of using rain gauge and rain radar. The effect of combined observations is to be evaluated by considering the decrease of measurement error due to combined use of design orthogonal observation methods. As an example, this study evaluated the rain gauge network of the Keum river basin, and showed how the density of rain gauges could be decreased by combining the radar observation. This study applied the researches on sampling error by North and Nakamoto(1989), Yoo et al. (1996) and Yoo (1997), also the simple NFD model for representing the rainfall field. The model parameters were decided using the rainfall characteristics (correlation time and length) estimated using the data collected in the Keum River Basin by 28 rain gauges and the operation rule of radar was assumed arbitrarily. This study considered the rain gauge density criteria provided by WMO(1994) and the rain gauge density installed in the Keum river basin to decrease the rain gauge density under the condition of introducing the radar.

Correlates of Depressive Symptoms among College Students on Jeju Island in Korea

  • Kim, Moon-Doo;Lee, Chang-In
    • Korean Journal of Health Education and Promotion
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    • v.20 no.4
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    • pp.13-26
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    • 2003
  • Objectives: The aim of the present study was to determine the prevalence depressive symptoms, and the correlates of depressive symptoms, and to propose countermeasures for individual depression risk factors among college students. Methods: One university and three colleges in Jeju-do were selected as the study population and a total of 1000 students were selected by multiphasic cluster sampling to represent each department and year within each college. Of the 945 total respondents, 421 were men and 524 were women. The Beck Depression Inventory was used to evaluate depression and the BDI STEN score was used to assess depressive symptoms. Multiple logistic regression analysis was performed for comparisons. Results: 1. The prevalence of depressive symptoms among men was 14.4%, while among women the level rose to 26.8%. 2. Those with poor life satisfaction scores were significantly more likely to have depressive symptoms than those with good life satisfaction (odds ratio (OR) = 2.62; (95% confidence interval (95%CI), 1.483-4.629). 3. Students over 23 years old were significantly more likely to have low levels of depressive symptoms than those under 18 (OR = 0.439; 95%CI, 0.247-0.779). 4. Groups with poor body image satisfaction had higher levels of depressive symptoms when compared to respondents who had good body image (OR = 2.847; 95%CI, 1.341-6.045). 5. Students with poor perceived health status were significantly more likely to have high levels of depressive symptoms than those with good perceived health status (OR = 2.029; 95%CI, 1.157-3.557). Conclusion: Universities and colleges should provide education programs, such as health education that facilitates the development of a healthy body image. In addition, they should focus on various scholarships that could improve satisfaction with student life, especially for alienated students. Furthermore, colleges should help direct students towards engagement in more productive work, and lead social policies away from the dominance of appearance.

An actual Analysis on the Determinants of the Private Security Agents Career Choices (민간경비원의 직업선택 동기 결정요인에 대한 실증분석)

  • Kim, Sang-Jin
    • Convergence Security Journal
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    • v.12 no.2
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    • pp.3-12
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    • 2012
  • This study is to investigate determinants of the private security agents' career choices. Random sampling of newly agents working at the private security firms in Gyeonggi-do and ChungChong-do was used. The period of under review was from May, 2010 to June, 2011 and the total number of interviews was 382. For this study using SPSSWIN 18.0, factor analysis(EFA/CFA), reliability analysis, discriminant analysis and descriptive statistics. The followings are conclusions. The first factor is' the value of job'. It consists of public security, contributions to our society and nation, protection public safety, spirit of sacrifice, crime prevention, and maintenance security. The second factor is 'ease of career choice'. Qualifying conditions are not particular and it is easy to get the job, as a result, this job is easy of access, they chose this job. The third factor is 'occupational stability'. They think this is a good job because the job is future-oriented so they chose this job. The fourth factor is' curiosity'. They became interested in this job, so they wanted to know about this job and then they chose this job.

The Study on Development of Low NOx Combustor with Lean Burn Characteristics for Microturbine (희박 예혼합 연소를 이용한 마이크로터빈의 저공해 연소기 개발에 관한 연구)

  • Yoon, Jeong-Jung;Lee, Heon-Seok
    • 유체기계공업학회:학술대회논문집
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    • 2003.12a
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    • pp.63-72
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    • 2003
  • In order to reduce NOx emissions in the 20kW class microturbine under development, the low NOx characteristics, as being an application to the lean premixed combustion technology, have been investigated. The study has been conducted at the conditions of high temperature and high pressure. Theair from a compressor with the pressure of 2.5bar, 3.0bar, 3.5bar was supplied to the combustor with the temperature 560K through the air preheat-treatment. The sampling exhaust gas was measured at the immediate exit of the combustor. For the effect of temperature on NO and CO emissions, though NOx were increased, CO was decreased with increasing inlet air temperature. With increasing inlet air pressure, NOx were increased and CO was decreased also. NOx were decreased, but CO was increased with increasing inlet air mass flow rate. The test has been performed on the equivalent ratio of 0.10 to 0.16 in the lean region. NOx were increased with increasing equivalent ratio, but CO was decreased as an influence of flame temperature. CFD work with an appropriate combustion model predicated a complicated swirling flow pattern in the combustor, and also produced a numerical value of NOx and CO emissions which was to be compared with the experimental one. As the results of this study, NOx are expected to be reduced to less than 42ppm at 15% O2 when operated at the design condition of the 20kW class microturbine.

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