• Journal of Intelligence and Information Systems
• /
• v.24 no.1
• /
• pp.183-203
• /
• 2018

News articles are the most suitable medium for examining the events occurring at home and abroad. Especially, as the development of information and communication technology has brought various kinds of online news media, the news about the events occurring in society has increased greatly. So automatically summarizing key events from massive amounts of news data will help users to look at many of the events at a glance. In addition, if we build and provide an event network based on the relevance of events, it will be able to greatly help the reader in understanding the current events. In this study, we propose a method for extracting event networks from large news text data. To this end, we first collected Korean political and social articles from March 2016 to March 2017, and integrated the synonyms by leaving only meaningful words through preprocessing using NPMI and Word2Vec. Latent Dirichlet allocation (LDA) topic modeling was used to calculate the subject distribution by date and to find the peak of the subject distribution and to detect the event. A total of 32 topics were extracted from the topic modeling, and the point of occurrence of the event was deduced by looking at the point at which each subject distribution surged. As a result, a total of 85 events were detected, but the final 16 events were filtered and presented using the Gaussian smoothing technique. We also calculated the relevance score between events detected to construct the event network. Using the cosine coefficient between the co-occurred events, we calculated the relevance between the events and connected the events to construct the event network. Finally, we set up the event network by setting each event to each vertex and the relevance score between events to the vertices connecting the vertices. The event network constructed in our methods helped us to sort out major events in the political and social fields in Korea that occurred in the last one year in chronological order and at the same time identify which events are related to certain events. Our approach differs from existing event detection methods in that LDA topic modeling makes it possible to easily analyze large amounts of data and to identify the relevance of events that were difficult to detect in existing event detection. We applied various text mining techniques and Word2vec technique in the text preprocessing to improve the accuracy of the extraction of proper nouns and synthetic nouns, which have been difficult in analyzing existing Korean texts, can be found. In this study, the detection and network configuration techniques of the event have the following advantages in practical application. First, LDA topic modeling, which is unsupervised learning, can easily analyze subject and topic words and distribution from huge amount of data. Also, by using the date information of the collected news articles, it is possible to express the distribution by topic in a time series. Second, we can find out the connection of events in the form of present and summarized form by calculating relevance score and constructing event network by using simultaneous occurrence of topics that are difficult to grasp in existing event detection. It can be seen from the fact that the inter-event relevance-based event network proposed in this study was actually constructed in order of occurrence time. It is also possible to identify what happened as a starting point for a series of events through the event network. The limitation of this study is that the characteristics of LDA topic modeling have different results according to the initial parameters and the number of subjects, and the subject and event name of the analysis result should be given by the subjective judgment of the researcher. Also, since each topic is assumed to be exclusive and independent, it does not take into account the relevance between themes. Subsequent studies need to calculate the relevance between events that are not covered in this study or those that belong to the same subject.

• Journal of Korean Society for Atmospheric Environment
• /
• v.25 no.2
• /
• pp.154-166
• /
• 2009

In this study, 1-hour integrated $PM_{2.5}$ mass and chemical composition concentrations were monitored at the St. Louis-Midwest Supersite in Illinois. Time-resolved samples were collected one week in each of June 2001 (22 June to 28 June), November 2001 (7 November to 13 November), and March 2002 (19 March to 25 March). A total of 427 samples were collected by CAMM (continuous ambient mass monitor) and 15 compounds were analyzed by AAS, PILS (particle-into-liquid sampler), and TOT (thermal optical transmittance) method. PMF was applied to identify the sources and apportion the $PM_{2.5}$ mass to each source for highly time resolved data. In addition, the nonparametric regression (NPR) was applied to identify the predominant directions of local sources relative to wind direction. Also, this study performed compare the NPR analysis and location of actual local point sources at the St. Louis area. The PMF modeling identified nine sources and the average mass was apportioned to gasoline vehicle, road dust, zinc smelter, copper production, secondary sulfate, diesel emission, secondary nitrate, iron+steel, and lead smelter, respectively. These results suggested that this study results will be help for $PM_{2.5}$ source apportionment studies at similar metropolitan area, establish $PM_{2.5}$ standard, and establish effective emissions reduction strategies in Korea.

• Journal of the Microelectronics and Packaging Society
• /
• v.23 no.2
• /
• pp.85-89
• /
• 2016

In this paper, we studied effects of tilting angle of band pass filter on the characteristics of fluorescence imaging system. Theoretical modeling showed that transmittance and filtering range are highly dependent on the tilting angle. Measurements on transmittance as a function of wavelength confirmed that changes in transmittance and the band filter range are in good agreement with theoretical prediction. Therefore, characteristics of band pass filter can be precisely tuned by altering tilting angle of band pass filter in order to enhance fluorescence signal in bio imaging system.

• International Journal of Aeronautical and Space Sciences
• /
• v.15 no.4
• /
• pp.356-365
• /
• 2014

This paper is the second in a series and aims to build a high-fidelity mathematical model for a propeller-driven airplane using the propeller's aerodynamics and inertial models, as developed in the first paper. It focuses on aerodynamic models for the fuselage, the main wing, and the stabilizers under the influence of the wake trailed from the propeller. For this, application of the vortex lattice method is proposed to reflect the propeller's wake effect on those aerodynamic surfaces. By considering the maneuvering flight states and the flow field generated by the propeller wake, the induced velocity at any point on the aerodynamic surfaces can be computed for general flight conditions. Thus, strip theory is well suited to predict the distribution of air loads over wing components and the viscous flow effect can be duly considered using the 2D aerodynamic coefficients for the airfoils used in each wing. These approaches are implemented in building a high-fidelity mathematical model for a propeller-driven airplane. Flight dynamic analysis modules for the trim, linearization, and simulation analyses were developed using the proposed techniques. The flight test results for a series of maneuvering flights with a scaled model were used for comparison with those obtained using the flight dynamics analysis modules to validate the usefulness of the present approaches. The resulting good correlations between the two data sets demonstrate that the flight characteristics of the propeller-driven airplane can be analyzed effectively through the integrated framework with the propeller and airframe aerodynamic models proposed in this study.

• Journal of the Korean Society of Marine Environment & Safety
• /
• v.19 no.3
• /
• pp.290-301
• /
• 2013

The docking analysis of a global ship structure is requested to evaluate its structural safety against the reaction forces at supports during docking works inside a dry dock. That problem becomes more important recently as the size of ships is getting larger and larger. The docking supports are appropriately arranged in a dock to avoid their excessive reaction forces which primarily cause the structural damages in docking a ship and, up to now, the structural safety has been assessed against the support arrangement by the finite element analysis (FEA) of a global ship structure. However, it is complicated to establish the finite element model of the ship in the current structural design environment of a shipyard and it takes over a month to finish the work. This paper investigates a simple and fast approach to carry out a ship docking analysis by a simplified grillage model and to assign the docking supports position on the model. The grillage analysis was considered from the motivation that only the reaction forces at supports are sufficient to assess their arrangement. Since the simplified grillage model of the ship cannot guarantee its accuracy quantitatively, modeling strategies are proposed to improve the accuracy. In this paper, comparisons between the proposed approach and three-dimensional FEA for typical types of ships show that the results from the present grillage model have reasonably good agreement with the FEA model. Finally, an integrated program developed for docking supports planning and its evaluation by the proposed approach is briefly described.

• Journal of the Korea Safety Management & Science
• /
• v.15 no.3
• /
• pp.7-17
• /
• 2013

The recent trend in modern systems development can be characterized by the increasing complexity in terms of both the functionality and HW/SW scale that seems to be accelerated by the growing user requirements and the rapid advancement of technology. Among the issues of complexity, the one related to systems safety has attracted great deal of attention lately in the development of the products ranging from mass-transportation systems to defence weapon systems. As such, the incorporation of safety requirements in systems development is becoming more important. Note, however, that since such safety-critical systems are usually complex to develop, a lot of organizations and thus, engineers should participate in the development. In general, there seems to be a variety of differences in both the breadth and depth of the technical background they own. To address the problems, at first this paper presents an effective design process for safety-critical systems, which is intended to meet both the systems design and safety requirements. The result is then advanced to obtain the models utilizing the systems modeling language (SysML) that is a de facto industry standard. The use of SysML can facilitate the construction of the integrated process and also foster active communication among many participants of diverse technical backgrounds. As a case study, the model-based development of high-speed trains is discussed.

• Spatial Information Research
• /
• v.18 no.5
• /
• pp.133-142
• /
• 2010

Many pedestrian or fire evacuation models have been studied last decades for modeling evacuation behaviors or analysing building structures under emergency situations. However, currently developed models do not consider the differences of visibility of pedestrians by obstacles such as furniture, wall, etc. The visibility of pedestrians is considered one of the important factors that affect the evacuation behavior, leading to making simulation results more realistic. In order to incorporate pedestrian's visibility into evacuation simulation, we should be able to give different walking speeds according to differences of visibility. We improved the existing floor field model based on cellular automata in order to implement the visibility. Using the space syntax theory, we showed how we split the indoor spaces depending on the different visibilities created by different levels of structural depths. Then, we improved the algorithm such that pedestrians have different speeds instead of simultaneous movement to other cells. Also, in order for developing a real time simulation system integrated w ith indoor sensors later, we present a process to build a 3D simulator using a spatial DBMS. The proposed algorithm is tested using a campus building.

• The Journal of Information Systems
• /
• v.24 no.2
• /
• pp.209-240
• /
• 2015

Purpose This study investigates the relationships between various attributes of smart banking (convenience, security, convergence, and economy), user features (familiarity and innovativeness), perceived usefulness, trust, satisfaction, and continuance intentions and provides a comparison of Google's Android OS and Apple's iOS. Design/methodology/approach We considered a sample of 245 respondents and used structural equation modeling to analyze the data. Findings The results indicate that convergence and familiarity significantly affected perceived usefulness and that security and economy significantly affected perceived trust in smart banking services. The relationships of security, economy, and innovativeness to perceived usefulness and those of convenience and familiarity to perceived trust were stronger for the Android OS than for iOS. The study contributes by proposing an integrated framework and providing a comparison between the Android OS and iOS in the context of smart banking.

• Journal of Digital Contents Society
• /
• v.9 no.1
• /
• pp.101-107
• /
• 2008

The level of transference of NGN is beginning as the operation of Access Gateway in korea at present, but NGN will keep developing continuously to the NGN integrated network until 2010. This research is finding the meaning and assignment of NGN QoS to deduct how to manage the control system and presenting the QoS control process and trial framework. The trial framework is the modeling of the QoS measurement metrics, the measurement time schedule, the section, hierarchy, instrument, equipment and method of measurement and the series of cycle & the methodology about analysis of the result of measurement. The objective standard of quality in communication service is guaranteed not by itself but by controlling and measuring continuously. Especially it's very important time to maintain the research about NGN QoS measurement and control because the big conversion of new network technology paradigm is now spreading.

• Journal of the Institute of Electronics and Information Engineers
• /
• v.49 no.9
• /
• pp.259-269
• /
• 2012

With the lower supply voltage and the higher operating frequency in integrated circuits, the analysis of the power distribution network (PDN) including on-chip inductances becomes more important. In this paper, an effective inductance extraction method for a regular on-chip power grid structure is proposed. The loop inductance model applicable to chip layout is proposed and the inductance extraction tool using the proposed inductance model based on post layout RC circuits is developed. The accuracy of the proposed loop model and the developed tool is verified by comparing the test circuit simulation results with those from the partial element equivalent circuit (PEEC) model. The voltage fluctuation from the RLC circuits extracted by the developed tool was examined for the analysis of on-chip inductance effects. The significance of on-chip power grid inductance was investigated by the co-simulation of chip-package-PCB.