• Journal of Environmental Science International
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• v.31 no.6
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• pp.503-513
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• 2022

This research investigated the effect of the eruption of Japan Sakurajima volcano on the concentration of ultrafine particle when the north Pacific high pressure exists in the Busan in summer. As a result of analyzing the forward trajectory using the HYSPLIT model, the air parcel from Sakurajima volcano passed through the sea in front of Busan at 1500 LST on July 17, 24 hours after the volcanic eruption. As a result of analyzing the PM₁₀ and PM_2.5 concentrations in the Busan for two days from July 16 to 17, 2018, the Sakurajima eruption in Japan, it can be seen that there was a high increase in PM₁₀ and PM_2.5 concentrations compared to the previous day. As a result of analyzing the backward trajectory, the air mass that reached Busan at 1300 LST on July 17, 2018 has moved near the Sakurajima volcano at 1,500 m, 2,000 m, and 3,000 m. The concentration of SO₄^2- in PM_2.5, the concentration of all three stations in Busan showed a sharp increase from 1000 LST on July 17th. Looking at the NH₄⁺ concentration in PM_2.5, it shows a very similar variation trend to SO₄^2-, and the correlation coefficient between the two components is 0.96 for Jangrimdong and Yeonsandong, and 0.85 for Busan New Port. Looking at the NO₃^- concentration in PM_2.5, the same high concentrations as SO₄² and NH₄⁺ were not observed in the afternoon of July 17th.

• Journal of the Korea Society of Computer and Information
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• v.29 no.3
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• pp.1-10
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• 2024

The research on predicting the routes of ships, which constitute the majority of maritime transportation, can detect potential hazards at sea in advance and prevent accidents. Unlike roads, there is no distinct signal system at sea, and traffic management is challenging, making ship route prediction essential for maritime safety. However, the time intervals of the ship route datasets are irregular due to communication disruptions. This study presents a method to adjust the time intervals of data using appropriate interpolation techniques for ship route prediction. Additionally, a deep learning model for predicting ship routes has been developed. This model is an LSTM model that predicts the future GPS coordinates of ships by understanding their movement patterns through real-time route information contained in AIS data. This paper presents a data preprocessing method using linear interpolation and a suitable deep learning model for ship route prediction. The experimental results demonstrate the effectiveness of the proposed method with an MSE of 0.0131 and an Accuracy of 0.9467.

• Journal of KIISE:Databases
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• v.31 no.5
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• pp.492-504
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• 2004

Recently, as growing of interest for LBS(location-based services) techniques, lots of works on moving objects that continuously change their information over time, have been performed briskly. Also, researches for NN(nearest neighbor) query which has often been used in LBS, are progressed variously However, the results of conventional NN Query processing techniques may be invalidated as the query and data objects move. Therefore, they are usually meaningless in moving object management system such as LBS. To solve these problems, in this paper we propose a new nearest neighbor query processing technique, called CTNN, which is possible to meet accurate and continuous query processing for moving objects. Our techniques include an Approximate CTNN(ACTNN) technique, which has quick response time, and an Exact CTNN(ECTNN) technique, which makes it possible to search nearest neighbor objects accurately. In order to evaluate the proposed techniques, we experimented with various datasets. Experimental results showed that the ECTNN technique has high accuracy, but has a little low performance for response time. Also the ACTNN technique has low accuracy comparing with the ECTNN, but has quick response time The proposed techniques can be applied to navigation system, traffic control system, distribution information system, etc., and specially are most suitable when both data and query are moving objects and when we already know their trajectory.

• Journal of Korea Game Society
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• v.10 no.4
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• pp.23-34
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• 2010

The current interests in e-sports is being extended to the fields of education these days. Professional game players, so called as 'Pro-Gamers', therefore, should be recognized as human resource for education, and the theoretical foundation for them needs to be established. This study examines informal learning styles, motivation, and interactions among professional game players in South Korea. The aim of this grounded theory study is to discover the trajectory of professional game players' experiences and explain what properties and interactions they are facing depending on the stage of the trajectory. This study conceptualizes educational meaning within and across the society of StarCraft Pro-Gamers, providing suggestions for the management of human resource using models constructed. Data was analyzed by interviewing 1 consultant, 2 directors and 9 Pro-Gamers. By analyzing the data, this study explored what learning strategies Pro-Gamers construct and apply in their trajectory as Pro-Gamers. It includes how they organize learning, how they formulate their motivation and goals, how they cooperate and compete, what curricula they adapt, how they become one of the ace players overcoming their slump, and how informal education works in practice in the interaction among members of a StarCraft Pro-Gamer team. Finally, in this paper the stage theory was presented. It is argued that when the stage of the players shifts (Stage Shifting). It also brings changes to proficiency properties, emotional properties, interactional properties and educational properties related to each stage. Stages are categorized by five levels: Enjoying, Struggling, Achieving, Slumping, and Recovering. Although each stage has its own properties, the stages are grouped by two main properties, one of which is a Communicative Stage and the other is a Practicing Stage.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.19 no.6
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• pp.208-221
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• 2020

The objective of this study is to estimate and analyze the traffic density of continuous flow using the trajectory of individual vehicles and the headway of sample probe vehicles-front vehicles obtained from ADAS (Advanced Driver Assitance System) installed in sample probe vehicles. In the past, traffic density of continuous traffic flow was mainly estimated by processing data such as traffic volume, speed, and share collected from Vehicle Detection System, or by counting the number of vehicles directly using video information such as CCTV. This method showed the limitation of spatial limitations in estimating traffic density, and low reliability of estimation in the event of traffic congestion. To overcome the limitations of prior research, In this study, individual vehicle trajectory data and vehicle headway information collected from ADAS are used to detect the space on the road and to estimate the spatiotemporal traffic density using the Generalized Density formula. As a result, an analysis of the accuracy of the traffic density estimates according to the sampling rate of ADAS vehicles showed that the expected sampling rate of 30% was approximately 90% consistent with the actual traffic density. This study contribute to efficient traffic operation management by estimating reliable traffic density in road situations where ADAS and autonomous vehicles are mixed.

• Journal of Construction Engineering and Project Management
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• v.9 no.2
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• pp.1-24
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• 2019

Poor project performance has been noted as the bane in the construction industry globally. This paper sought to investigate, by way of literature, the performance patterns of construction projects in Kenya since independence (1963-2018). This was informed by reports of undesirable project performance in the industry. This descriptive study used available studies previously done in this subject area. In sum, literature is replete with evidence on a myriad of challenges facing the execution of projects. The study established that generally, the project performance is poor and has assumed a chronic trajectory spanning over five decades. On average, the findings reveal that 35-60% of projects initiated in Kenya face cost overruns while time overrun is most severe with 35-73% projects overrunning their schedule. In addition, the findings problematize the issue of plurality of performance measurement regimes in the construction industry. Here, it was observed that no singular construct exists to objectively measure the various facets that constitute the 'health' of a project. This paper has contributed to the body of knowledge by examining the performance patterns in Kenya for over fifty years while at the same time identifying the bottlenecks inherent in projects execution. Importantly, the conceptual performance efficiency framework derived in the current study presents a paradigm shift in the monitoring and evaluation of projects. To this end, an in-depth analysis is recommended on the interaction of efficiency enablers in the buildup of performance efficiency index (PEI). Similarly, a further inquiry is recommended on the integration and impact of the proposed framework in the management of projects.

• Journal of Technology Innovation
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• v.14 no.1
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• pp.1-30
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• 2006

The purpose of this paper is to analyze the organizational design and management of product development in creating new product architecture by an established firm. For the purpose, the paper put up the organizational design in the process of PDA(Personal Digital Assistant) development of Sharp and Casio which were Japanese major PDA firms in 1990s. PDA is the product born through architectural change from Electronic Organizer. Prior research on the product architecture change and organizational adaptation emphasized that an established firm is difficult to adapt to new product architecture due to the restriction of prior technology or organizational inertia. For overcoming these problems and successful development of new product architecture, organizational design and management in the process of product development becomes essential. In case of Sharp, corporate development project team had been used to overcome the restrictions from architectural knowledge accumulated through previous product. After launching first new PDA by corporate development project team, Sharp created a new division and pushed an evolution of PDA, when new PDA market start to grow up rapidly toward a major market segmentation. As a result, Sharp was able to build up stable PDA project trajectory. However, Casio was late for three years in launching of new PDA architecture because previous division charging of Electronic Organizer tried to develop first new PDA. Casio's PDA development was prohibited by engineers of previous division because new PDA architecture was inferior on user interface and display definition. That is, Casio's first PDA development was restricted by architectural knowledge of previous product.

• Proceedings of the Technology Innovation Conference
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• 2005.06a
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• pp.44-68
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• 2005

The purpose of this paper is to analyze the organizational design and management of product development in creating new product architecture by an established firm. For the purpose, the paper put up the organizational design in the process of PDA(Personal Digital Assistant) development of Sharp and Casio which were Japanese major PDA firms in 1990s. PDA is the product born through architectural change from Electronic Organizer. Prior research on the product architecture change and organizational adaptation emphasized that an established firm is difficult to adapt to new product architecture due to the restriction of prior technology or organizational inertia. For overcoming these problems and successful development of new product architecture, organizational design and management in the process of product development becomes essential. In case of Sharp, corporate development project team had been used to overcome the restrictions from architectural knowledge accumulated through previous product. After launching first new PDA by corporate development project team, Sharp created a new division and pushed an evolution of PDA, when new PDA market start to grow up rapidly toward a major market segmentation. As a result, Sharp was able to build up stable PDA project trajectory. However, Casio was late for three years in launching of new PDA architecture because previous division charging of Electronic Organizer tried to develop first new PDA. Casio's PDA development was prohibited by engineers of previous division because new PDA architecture was inferior on user interface and display definition. That is, Casio's first PDA development was restricted by architectural knowledge of previous product.

• Journal of the Korea Institute of Military Science and Technology
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• v.21 no.4
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• pp.551-561
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• 2018

Footprint is defined as ground area that is projected from the outer edges of the battle space protected by a defence system. This concept can be effectively used for making decisions on site selection of anti missile systems to defend against enemy's ballistic missiles. In this paper, simulations of ballistic missile trajectories based on various launch conditions are performed first and then the footprint is derived with engagement zone set as a boundary condition. Results of the simulation with various relative positions between the defense system and defended asset are also presented. The proposed method, in which the trajectories are generated based on launch point of the ballistic missile, has an advantage of approximating the defended area close to reality. Two applications are introduced in the present paper to describe how the derivation of defended area could be utilized in deployment decision of defense systems.

• The Korean Journal of Health Service Management
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• v.11 no.4
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• pp.115-132
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• 2017

Objectives : The purpose of this study was to investigate the depressive change and predictors of chronic illnesses and to examine whether depressive change predictors are different according to chronic disease types. Methods : Data from the 1st to the 10th year of the Korean Welfare Panel of 5,023 adults over 20 years of age who were treated for chronic diseases for more than three months were examined. We assessed demographic, sociological, and socioeconomic factors including depression predictors of chronically ill patients, and analyzed the data using latent growth modeling and multiple group analysis. Results : Depression symptoms of chronically ill patients gradually decreased, showing a linear relationship across time. In addition, multiple group analysis was performed for each type of chronic disease. Conclusions : We described the phenomenon of depression in chronically ill patients, and discussed the practical and policy interventions required to improve depression in chronically ill patients.