• Journal of Fisheries and Marine Sciences Education
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• v.29 no.1
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• pp.31-39
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• 2017

The paper presents the Philippine maritime condition, safety systems and navigational aids. It aims to uplift the maritime safety systems and infrastructures by studying the different strata of the industry, thereby emphasizing on the structures, weaknesses and opportunities. It presents the different maritime agencies involved and each responsibilities. Data from PPA demonstrate the statistics of increase in the cargo throughput, passenger, shipcalls and cargo-container handled in the year 2014. It also highlights the insufficiency of different navigational aids, VTMS, MBS and TSS placed in the whole archipelago. It gathers data of maritime accidents in 10-year period, 2006-2015, showing the most occurred accidents, casualties and areas these accidents happened. It includes the weather phenomena which contribute to the maritime movements and accidents incidence. The results show that systems and infrastructures that focus on the lack of improvement in technology and over-lapping functions of different agencies of government require development and upgrading.

• Journal of Digital Contents Society
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• v.10 no.3
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• pp.395-400
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• 2009

The wide spread of the Internet service has brought in web GIS development. But, there are problems of the user access latencies, the network traffic, and the server overload in Internet Geographic Information System because spatial data are transferred in large volumes. In this paper, I propose a cache algorithm on client side to solve the above problems. The proposed algorithm demonstrates the performance improvement over known studies by utilizing unit time and spatial proximity. In addition, this paper conducts a performance evaluation to measure the improvement in algorithm efficiency and analyzes the results of the performance evaluation. When spatial data queries are conducted, according to our performance evaluation, hit rate has been improved over the existing algorithms.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.17 no.8
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• pp.1879-1884
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• 2013

The general bus system architecture consists of masters, slaves, arbiter, decoder and so on in shared bus. As several masters can't use a bus concurrently, arbiter plays an role in bus arbitration. In compliance with the selection of arbitration method, The efficiency of bus usage can be determined. Fixed Priority, Round-Robin, TDMA, Lottery arbitration are studied in conventional arbitration method. In this paper, we draw the performance analysis of Fixed Priority, Round Robin, TDMA and Lottery bus arbitration policies due to the data traffic concentration and propose the methods of performance improvement.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.31 no.1
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• pp.43-56
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• 2023

The aviation industry has continued to grow despite the influence of external environmental factors such as SARS and MERS. However, this growth has led to a sharp decrease in air traffic and a crisis of flight suspension due to the collapse of the global value chain and the decline of the world economy as the World Health Organization (WHO) declared a COVID-19 pandemic. Due to the decrease in the number of international flights, aviation workers such as pilots and cabin crew were exposed to high psychological stress and fatigue, such as large-scale layoffs, job instability, decrease in income, and increased risk of infection during. Recently, the international community has eased immigration restrictions through quarantine activities, and airlines are taking a step further to recover existing air demand. However, during the crisis period, a significant number of professional workers have been turned off or fired, and the physical and mental fatigue of those who can perform their duties is increasing. Therefore, this paper intends to examine the direction of policy improvement and the identification of problems in aviation safety and fatigue management after the pandemic.

• International Journal of Highway Engineering
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• v.13 no.1
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• pp.119-127
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• 2011

The main purpose of this paper is to apply Zone 30 system which is being experimented in advanced country for the solution of controlling the residential street's speed to our country with the consideration of the real condition of our street and traffic and to run this system as an example to analyze the effect and at the same time, analyze the problem and get appropriate preparation for this system to be widespread. The area to run this model project is Goyang City Ilsan-Gu.($0.65km^2$) which is close with the commercial area reflecting the opinion of experts and an on-site verification by the National Police Agency T/F and is having a heavy pedestrian traffic and the risk of pedestrian accident. Firstly we defined residential street and residential street area to review the system and devided the residential street type to establish a plan of operation. Afterwards, we thoroughly examined the model project area and analyzed the problem and solution. We finally completed establishing a facilities by conference with a local autonomous entity with the improvement of facility's sketch at the analysis of the model project area. The result of effects analysis which we devided after and before of establishment is that vehicle speed be reduced 5~15km/h, and traffic accidents has decreased by 24 percent.

• Journal of the Korea institute for structural maintenance and inspection
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• v.28 no.1
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• pp.70-81
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• 2024

In this study, Tridimensional Hybrid Isolation System(THIS) was proposed as a vibration isolator for traffic loads, combining vertical and horizontal isolation systems. Its efficacy in improving serviceability for vertical vibration was analytically evaluated. Firstly, for the analysis, the major vibration modes of the existing apartment were identified through eigenvalue analysis for the system and pulse response analysis for the bedroom slab using commercial structural analysis software. Subsequently, a 16-story model with horizontal, vertical and rotational degrees of freedom for each slab was numerically organized to represent the achieved modes. The dynamic analysis for the measured acceleration from an adjacent ground to high-speed railway was performed by state-space equations with the stiffness and damping ratio of THIS as variables. The result indicated that as the vertical period ratio increased, the threshold period ratio where the slab response started to be suppressed varied. Specifically, when the period ratio is greater than or equal to 5, the acceleration levels of all slabs decreased to approximately 70% or less compared to the non-isolated condition. On the other hand, it was ascertained that the influence of damping ratios on the response control of THIS is inconsequential in the analysis. Finally, the improvement in vertical vibration performance of THIS was evaluated according to design guidelines for floor vibration of AIJ, SCI and AISC. It was confirmed that, after the application of THIS, the residential performance criteria were met, whereas the non-isolated structure failed to satisfy them.

• Journal of the Society of Disaster Information
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• v.16 no.4
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• pp.734-746
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• 2020

Purpose: Increase in the size and number of underpasses rises occurrence of disasters such as fire and flooding inundation in underpasses. In the occurrence of disasters, the underpasses are more vulnerable to expose of crucial disasters than the general roads due to they are built underground. Therefore, The purpose of this paper is to derive system improvement items to prevent and control disasters in underpasses. Method: A hierarchical model of disaster impact factors and alternatives was developed based on prior researches and expert advices on disaster analyses and impact factors in the underpasses. The developed model was employed for surveys of pairwise comparison, and rankings of improvement were determined by applying the AHP method. Result: With a consistency of the surveys, results of relative weights of evaluation criteria(traffic accidents, fire, flooding inundation) and alternatives(law, system/planning, maintenance/human factor/environment) shows that improvement of laws and system related to the fire disaster is a top priority to prevent and control disaster of the underpasses. Conclusion: From experts' point of view, strengthening laws and systems related to disater prevention facilities such as water spray facilities, external(ground) exit in relation to fire in underpasses showed that it is an alternative to prevent disasters and minimize damage to underpasses.

• Journal of Korean Society of Transportation
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• v.35 no.1
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• pp.63-78
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• 2017

The purpose of this study is to determine the optimal aggregation interval to increase the reliability when estimating representative value of individual vehicle travel time collected by DSRC equipment in interrupted traffic flow section in National Highway. For this, we use the bimodal asymmetric distribution data, which is the distribution of the most representative individual vehicle travel time collected in the interrupted traffic flow section, and estimate the MSE(Mean Square Error) according to the variation of the aggregation interval of individual vehicle travel time, and determine the optimal aggregation interval. The estimation equation for the MSE estimation utilizes the maximum estimation error equation of t-distribution that can be used in asymmetric distribution. For the analysis of optimal aggregation interval size, the aggregation interval size of individual vehicle travel time was only 3 minutes or more apart from the aggregation interval size of 1-2 minutes in which the collection of data was normally lost due to the signal stop in the interrupted traffic flow section. The aggregation interval that causes the missing part in the data collection causes another error in the missing data correction process and is excluded. As a result, the optimal aggregation interval for the minimum MSE was 3~5 minutes. Considering both the efficiency of the system operation and the improvement of the reliability of calculation of the travel time, it is effective to operate the basic aggregation interval as 5 minutes as usual and to reduce the aggregation interval to 3 minutes in case of congestion.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.15 no.1
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• pp.109-118
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• 2016

Traffic congestions are rapidly increasing in urban areas. In order to reduce these problems, it needs real-time data and intelligent techniques to quickly identify traffic activities with useful information. This paper proposes a Fuzzy Domain Ontology(FDO)-based opinion mining system to monitor the transportation network in real-time as well to make a city polarity map for travelers. The proposed system retrieves tweets and reviews related to transportation activities and a city. The feature opinions are extracted from these tweets and reviews and then used FDO to identify transportation and city features polarity. This FDO and intelligent prototype are developed using $Prot{\acute{e}}g{\acute{e}}$ OWL (Web Ontology Language) and JAVA, respectively. The experimental result shows satisfactory improvement in tweets and review's analyzing and opinion mining.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.32 no.6D
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• pp.539-547
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• 2012

Increasing the mode transfer volume between public transportation modes has known to be necessary for efficiency improvement of public transportation system operation and it is also found to be important to have relevant transfer point selection with reflection of current travel pattern. This study is in regards to providing a selection guideline for the location of transfer point between public transport modes. This case study has been carried out for Daegu Metropolitan City especially for public transportation users behaviour by analysis of daily usage of transportation card to identify the transfer travel pattern. A cluster analysis was applied to categorize the pattern of transfer stop which induces many users and a discriminant analysis also utilized for grouping the stops by number of transfer trip. This research produces the estimation result of transfer volume for urban railway system no.3 in Daegu City which is currently under construction. In addition, the locations of transfer center has also been proposed.