• 한국경영과학회지
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• 제40권4호
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• pp.49-63
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• 2015

Keyword indexed in multidisciplinary journals show trends about science and technology innovation. Nature and Science were selected as multidisciplinary journals for our analysis. In order to reduce the effect of plurality of keyword, stemming algorithm were implemented. After this process, we fitted growth curve of keyword (stem) following bass model, which is a well-known model in diffusion process. Bass model is useful for expressing growth pattern by assuming innovative and imitative activities in innovation spreading. In addition, we construct keyword co-occurrence network and calculate network measures such as centrality indices and local clustering coefficient. Based on network metrics and yearly frequency of keyword, time series analysis was conducted for obtaining statistical causality between these measures. For some cases, local clustering coefficient seems to Granger-cause yearly frequency of keyword. We expect that local clustering coefficient could be a supportive indicator of emerging science and technology.

• 대한조현병학회지
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• 제23권2호
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• pp.58-64
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• 2020

Objectives: In this study, we conducted an exploratory analysis of the current media trends on schizophrenia using text-mining methods. Methods: First, web-crawling techniques extracted text data from 575 news articles in 10 major newspapers between 2018 and 2019, which were selected by searching "schizophrenia" in the Naver News. We had developed document-term matrix (DTM) and/or term-document matrix (TDM) through pre-processing techniques. Through the use of DTM and TDM, frequency analysis, co-occurrence network analysis, and topic model analysis were conducted. Results: Frequency analysis showed that keywords such as "police," "mental illness," "admission," "patient," "crime," "apartment," "lethal weapon," "treatment," "Jinju," and "residents" were frequently mentioned in news articles on schizophrenia. Within the article text, many of these keywords were highly correlated with the term "schizophrenia" and were also interconnected with each other in the co-occurrence network. The latent Dirichlet allocation model presented 10 topics comprising a combination of keywords: "police-Jinju," "hospital-admission," "research-finding," "care-center," "schizophrenia-symptom," "society-issue," "family-mind," "woman-school," and "disabled-facilities." Conclusion: The results of the present study highlight that in recent years, the media has been reporting violence in patients with schizophrenia, thereby raising an important issue of hospitalization and community management of patients with schizophrenia.

• 한국IT서비스학회지
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• 제14권1호
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• pp.237-249
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• 2015

The volume of unstructured text data generated by various social media has been increasing rapidly; therefore, use of text mining to support decision making has also been increasing. Especially, issue Clustering-determining a new relation with various issues through clustering-has gained attention from many researchers. However, traditional issue clustering methods can only be performed based on the co-occurrence frequency of issue keywords in many documents. Therefore, an association between issues that have a low co-occurrence frequency cannot be discovered using traditional issue clustering methods, even if those issues are strongly related in other perspectives. Therefore, issue clustering that fits each of criteria needs to be performed by the perspective of analysis and the purpose of use. In this study, a multi-dimensional issue clustering is proposed to overcome the limitation of traditional issue clustering. We assert, specifically in this study, that issue clustering should be performed for a particular purpose. We analyze the results of applying our methodology to two specific perspectives on issue clustering, (i) consumers' interests, and (ii) related R&D terms.

• 환경영향평가
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• 제21권4호
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• pp.581-591
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• 2012

The purpose of this study was to analyze the characteristics of fine particles concentration and meteorological parameters, and long range transport of wintertime Asian dust at Busan. Also we studied occurrence frequency and tendency of wintertime Asian dust from 1961 to 2010 in Korea. Asian dust occurred most frequently in the spring, the next to winter in Korea. Wintertime Asian dust is steadily increasing recently. Asian dust in Busan was the most occurred in 2001 with 21 days, followed by 12 days in 2002, and 10 days in 2006. The annual mean frequency during the past 12 years(1999~2010) was 7.5 days, and it was two times more than that during the past 50 years(3.8 days). Wintertime Asian dust in Busan has occurred 6 episodes since 2008, and it all occurred in December except for 20 Feb. 2009. The highest concentration of wintertime Asian dust was recorded mostly at Hakjangdong and Jangrimdong which are industrial area. Maintenance time of Asian dust at Busan was from 1hr 30min to 9hr 20min, it was shorter than in the spring. It took from 10 to 15 hours move to Busan after Asian dust was first detected in Korea. Wintertime Asian dust originated from Gobi desert in Mongolia and inner Mongolia near China, except for 9 Dec. 2008 at Busan.

• 물과 미래
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• 제16권4호
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• pp.253-257
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• 1983

In an attempt to study the frequency and characteristics of typhoons which hit the Korean Peninsula a period of 40 years from 1946 through 1979 was covered to collect necessary data with respect to occurrence of typhoons and their influence Typhoons which occurred between 1959 and 1980 were grouped according to their treking routes and strengths for detailed analyses. The results are summarized as follow; 1. The average annual occurrence of typhoons in the western pacific ocean was found to be 28, only two of which attacked the Korean Peninsula. 2. The annual probabilities of typhoons attacking were 0.925 for one or more, 0.700 for twice or more and 0.323 for there times or moro. 3. The monthly probabilities were found to be 0.228 in July, 0.434 in August and 0.194 in September. 4. An half of the typhoons which hit the Korean Pennisula passed through the western coast and the rest through the southern and eastern coasts in similan proportions. 5. The western coast is hit most frequently in July and less afterwords, visa-vis the southern and the eastern coast. 6. The minimum SLP averaged 983 mb and ordered by the treking routes as S

• Nuclear Engineering and Technology
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• 제47권3호
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• pp.362-379
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• 2015

In this study, Nuclear Power Plant (NPP) construction schedule delay risk assessment methodology is developed and the construction delay risk is assessed for turnkey international NPP projects. Three levels of delay factors were selected through literature review and discussions with nuclear industry experts. A questionnaire survey was conducted on the basis of an analytic hierarchy process (AHP) and Relative Importance Index (RII) methods and the schedule delay risk is assessed qualitatively and quantitatively by severity and frequency of occurrence of delay factors. This study assigns four main delay factors to the first level: main contractor, utility, regulatory authority, and financial and country factor. The second and the third levels are designed with 12 sub-factors and 32 sub-sub-factors, respectively. This study finds the top five most important sub-sub-factors, which are as follows: policy changes, political instability and public intervention; uncompromising regulatory criteria and licensing documents conflicting with existing regulations; robust design document review procedures; redesign due to errors in design and design changes; and worldwide shortage of qualified and experienced nuclear specific equipment manufacturers. The proposed combined AHP-RII methodology is capable of assessing delay risk effectively and efficiently. Decision makers can apply risk informed decision making to avoid unexpected construction delays of NPPs.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2004년도 Proceedings of ISRS 2004
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• pp.306-309
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• 2004

The susceptibility of landslides and the effect of landslide-related factors at Penang in Malaysia using the Geographic Information System (GIS) and remote sensing data have been evaluated. Landslide locations were identified in the study area from interpretation of aerial photographs and from field surveys. Topographical and geological data and satellite images were collected, processed, and constructed into a spatial database using GIS and image processing. The factors chosen that influence landslide occurrence were: topographic slope, topographic aspect, topographic curvature and distance from drainage, all from the topographic database; lithology and distance from lineament, taken from the geologic database; land use from Landsat TM (Thermatic Mapper) satellite images; and the vegetation index value from SPOT HRV (High Resolution Visible) satellite images. Landslide hazardous areas were analysed and mapped using the landslide-occurrence factors employing the probability-frequency ratio method. To assess the effect of these factors, each factor was excluded from the analysis, and its effect verified using the landslide location data. As a result, land 'cover had relatively positive effects, and lithology had relatively negative effects on the landslide susceptibility maps in the study area. In addition, the landslide susceptibility maps using the all factors showed the relatively good results.

• 한국환경과학회지
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• 제15권7호
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• pp.623-634
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• 2006

In this study, characteristics of fog at Mokpo as the west coastal area of Jeonnam were investigated, using statistical analysis of observed fog and meteorological data. Higher frequency of the fog occurrence at Mokpo was showed in spring(32%) and summer(34%) due to the seasonal high atmospheric pressure. Regional characteristics as radiation cooling, advection of fog and water vapor from surrounding sea and Yeongsan lake, and frontal fog had major effect on the coastal fog at Mokpo on the meteorological conditions of north-west/south wind and calm($0{\sim}2m/s$). Also, as the results of analyzing data of before and after the construction of Yeongsan dam, the frequency of annual mean fog days increased 41 %, specially increased 178% in autumn. The increase of fog days mainly resulted from evaporation during colder seasons and from temperature inversion during warmer seasons over the water surface of Yeongsan lake. The construction of Yeongsan dam had a little effect on the meteorological conditions concerning fog occurrence, because Yeongsan dam which only supplies the water for use do not always carry out outlet of the cold water. In addition, the sea fog at Heuksando located in offshore had not effect on the occurrence of fog at Mokpo.

• 한국환경과학회지
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• 제29권7호
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• pp.761-772
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• 2020

This research investigated the meteorologically relevant characteristics of high PM_2.5 episodes in Busan. The number of days when daily mean PM₁₀ concentration exceeded 100 ㎍/㎥ and the PM_2.5 concentration exceeded 50 ㎍/㎥ over the last four years in Busan were 24 and 58, respectively. Haze occurrence frequency was 37.6% in winter, 27.4% in spring, 18.6% in fall, and 16.4% in summer. Asian dust occurrence frequency was 81.8% in spring, 9.1% in fall and winter, and 0% in summer. During summer in Busan, high PM_2.5 episode occurred under the following meteorological conditions. 1) Daytime sea breeze. 2) Mist and haze present throuout the day. 3) Anti-cyclone located around the Korean peninsula. 4) Stable layer formed in the lower atmosphere. 5) Air parcel reached Busan by local transport rather than by long-range transport. These results indicate that understanding the meteorological relevance of high PM_2.5 episodes could provide insight for establishing a strategy to control urban air quality.

• Environmental Sciences Bulletin of The Korean Environmental Sciences Society
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• 제4권3호
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• pp.127-137
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• 2000

This study presents an analysis of the characteristics of vertical ozone distribution near the surface using ozonesonde data(l995 to 1998), plus surface ozone and meteorological data from the Pohang region. These features were examined in detail using three case studies. The first related to episodes of high surface ozone concentrations during the Spring season when the frontogenesis between the high and low pressure associated with the upper-level jet stream was found to be located near the surface. The second was a 5-day winter period(l3 -17 December, 1997) in the Pohang province when the hourly concentrations exceeded 90 ppb on several occasions owing to low-level jets(LLJs) induced by a nocturnal stable layer. Accordingly, this explains why the high surface ozone concentrations occurred at night as the ozone was transported across the zone by a strong wind speed( over 12.5 ms .1). The third case study was ozone enhancement due to photochemical reactions. In this case, the maximum concentration of ozone exceeded 60 ppb in the summer(23 -28 August, 1997). When an ozone peak appeared within the boundary layer, the occurrence frequency of a low-level jet due to the nocturnal stable layer was about 77%, similarly the occurrence frequency of a near-surface ozone peak relative to the appearance of an LLJ was about 76%. Accordingly, there is clearly a close correlation between the occurrence of LLJs and near-surface ozone peaks.