• KSII Transactions on Internet and Information Systems (TIIS)
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• v.15 no.7
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• pp.2531-2546
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• 2021

For several years, virtual reality (VR) and augmented reality (AR) technologies have been improving. However, some hurdles remain that slow down the distribution of VR and AR devices, such as head-mounted display (HMD), and related consumer content. One issue is VR motion sickness, which has been experienced by users using 360 degree VR content via HMD. This paper discusses the related international standardization work that classifies the factors causing VR sickness, and proposes the process for VR sickness level evaluation. Among the factors causing VR sickness, many research institutes regard minimizing MTP (Motion-to-Photon) latency as the key enabler to mitigate VR sickness. Thus, this paper introduces research trends of MTP latency measurement and MTP latency mitigation. This paper categorizes the research on MTP latency measurement into 2 categories of hardware-based approach and software code-level approach. The 2 approaches have different pros and cons depending on use-case, purpose, and architecture of each multimedia system. The pros and cons are addressed in this paper. Additionally, the research on mitigating MTP latency with diverse strategies such as proactive computing, caching, and edge server technology is explained, and compared to conventional technologies, shows improved performance.

• Steel and Composite Structures
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• v.38 no.1
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• pp.79-86
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• 2021

Due to the complex geological conditions, a large number of high quality coal seams was buried in the western of China which cannot be mining in open-pit methods. The dynamic properties of that coal cannot be studied easily in real site for the complex working condition. The compound coal blocks made on the basis of the real situation were studied in the laboratory. The physical and mechanical properties of the compound coal blocks and the raw coal were contrasted by using the UCS tests. The results show that the compound coal blocks made by mixing coal powder, cement and water in proportion of 2.5:2:1 are the closest to that of standard raw coal. Then the propagation of strain waves and crushing effects on the coal were studied in the compound coal blocks by using the super dynamic strain test system and the numerical calculated method of ANSYS/LS-DYNA. The results show that the diameter of the crushing zone in the compound coal blocks was similar to that in the numerical results. The fractures distribution in laboratory tests also has a similar trend to the calculation results. The measured strain waves at the distance of 50 cm, 100 cm, and 150 cm from the center of the charge are mainly concerned at -1.0×104 με and have a similar trend as that in the numerical simulation.

• Ocean and Polar Research
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• v.44 no.1
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• pp.99-111
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• 2022

Together with the development of measurement techniques, radiocarbon (¹⁴C) has been increasingly used as a key tool to investigate carbon cycling and associated biogeochemistry in the ocean. In this paper, the current status of radiocarbon studies in the East Sea (Japan Sea) is reviewed. Previously, spatiotemporal distribution and change of the water masses in the East Sea from 1979 to 1999 were investigated by using the ¹⁴C in the dissolved inorganic carbon (DIC). Researches on sinking particulate organic carbon (POC) revealed that POC in the deep ocean has more complex and heterogeneous origins than we expected. In particular, since 2011, Korean researchers have been collecting sinking particle samples for more than 10 years, so it is expected that ¹⁴C of POC will provide important information to understand carbon cycling in relation to climate change. Although the quantity of ¹⁴C data published in the East Sea is still limited, the importance and the future direction of using ¹⁴C to understand the biogeochemical mechanisms of carbon cycling and its role as a carbon reservoir in the East Sea are detailed herein.

• Journal of the Society of Naval Architects of Korea
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• v.58 no.6
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• pp.424-430
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• 2021

Fire localization is a key mission that must be preceded for an autonomous fire suppression system. Although studies using a variety of sensors for the localization are actively being conducted, the fire localization is still unfinished due to the high cost and low performance. This paper presents the modeling and simulation of the fire localization estimation using Bayesian estimation to determine the probabilistic location of the fire. To minimize the risk of fire accidents as well as the time and cost of preparing and executing live fire tests, a 40m × 40m-virtual space is created, where two ultraviolet sensors are simulated to rotate horizontally to collect ultraviolet signals. In addition, Bayesian estimation is executed to compute the probability of the fire location by considering both sensor errors and uncertainty under fire environments. For the validation of the proposed method, sixteen fires were simulated in different locations and evaluated by calculating the difference in distance between simulated and estimated fire locations. As a result, the proposed method demonstrates reliable outputs, showing that the error distribution tendency widens as the radial distance between the sensor and the fire increases.

• Journal of the Korean Society of Industry Convergence
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• v.24 no.6_2
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• pp.745-751
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• 2021

The International Maritime Organization(IMO) has established Emission Control Areas(ECA) in the Baltic Sea, North Sea, and sea areas in the United States since 2012, and encourages the use of clean fuels such as Natural Gas(NG). To keep pace with the increase in international demand for LNG bunkering vessels, research for the localization of key equipment for LNG bunkering must also be performed in Korea. For research and development of core bunkering equipment and systems, in this study, heat transfer analysis and structural analysis were performed by modeling the saddle, which must first be secured structurally by directly receiving the load of the hose. As a result, the suitability of the model was reviewed by analyzing the temperature distribution and stress level through the analysis results of this study.

• The Journal of Asian Finance, Economics and Business
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• v.10 no.1
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• pp.133-143
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• 2023

The detrimental impacts of financial instability on the world economy during the financial crisis highlighted the requirement to understand the existing financial circumstances. Stability and developments in financial conditions are important for economic prosperity. This study analyses the impact of geopolitical risk on the economic conditions of some specific emerging economies using monthly data from January 1999 to September 2016 by applying a fixed-effects panel data model. The estimation results demonstrated that geopolitical risk has a significant, negative impact on financial conditions. It shows geopolitical risk could be seen as a key factor that contributes towards financial conditions. Further, it implies that negative shocks of high geopolitical risk experienced by emerging economies are one of the primary reasons for the financial conditions' deterioration. The findings provide important insights for governments, policymakers, and investors. For instance, governments and politicians should refrain from expressing or producing tension, economic discomfort, or news that is likely to increase a high geopolitical risk. Maintaining a close eye on geopolitical risk and its sources may also help to stabilize financial conditions and develop a well-functioning financial system. As a result, investors would be better informed about an economy's economic and financial conditions, allowing them to diversify their international portfolios and devise investing strategies during uncertain economic times.

• Journal of Soil and Groundwater Environment
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• v.28 no.6
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• pp.45-57
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• 2023

To assess land subsidence estimation and preparedness in the Geum River basin, this study applied GIS techniques and identified six key areas. The Geum River basin has experienced an increase in heavy rainfall since late 2010, and four study areas have shown an increase in groundwater levels. Land subsidence primarily occurred from June to September, with higher rainfall years in 2020 and 2023. Approximately 83.6% of land subsidence in Chungcheongbuk-do province occurred in Cheongju-si, mainly attributed to aging sewage pipes. The regions experiencing population growth have likely led to the construction of underground infrastructures and sewer pipes. Thus, it is considered that various factors, including sewage pipe leaks, precipitation, slope gradient, low drainage density, and groundwater level fluctuations, have contributed to land subsidence. Improving land subsidence estimation involves incorporating additional natural factors and human activities.

• Journal of Distribution Science
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• v.7 no.2
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• pp.89-119
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• 2009

The purpose of this research is showing an appropriate way of maximizing customer service and establishing VOC system by analyzing different voices from complaining customers as well as loyal customers. This research is also aimed at figuring out how companies can implement effective service marketing methods in the field complying with customers' needs and how they can survive in the competition. The range of research is confined to 5 marketing companies and their web-sites on which customers can get logged and directly post their claims. These web-sites showed how those 5 companies cope with customer claims. A questionnaire research was made in A's store to evaluate customer satisfaction. These are conclusions drawn by this research. First, prompt reactions of sincerity to customers' claims contribute to building favorable corporate images. Second, the preference to VOC channels varies with age and sex. Marketers should implement respectively different channels for customers under age 30 and those over age 40. Women have a tendency to prefer instant phone conversations and want to have their claims well listened to. Third, a series of shift in customer trend drives companies into establishing their own interactive VOC systems based on customers' preferences. Customer-oriented management has become a key factor for survival in recent intensely competitive market situation, as the web-based e-commerce market has been rapidly growing accompanied with a dramatic advance of network marketing methods. This research suggests some practical methods to establish a customer-oriented VOC system that can be easily adopted in the field.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2004.11a
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• pp.211-218
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• 2004

The WAM wave model has been widely used for wave hindcasting in the ocean by many domestic and foreign researchers due to its relative simplicity and high accuracy. As this model was originally developed for the condition cf deepwater and comparatively coarse grid size covering wide area, it might produce in a fault result mused by the improper distribution of directional spreading. We extensively investigated involved problems based on WAM Cycle 4 model and suggested the improved WAM model so that it is applicable to both shallow water sea and fine mesh wave simulation. The modified WAM model is verified here by comparing the computed result with and the observed data at Ieodo Ocean Research Station for September of 2003.

• Archives of design research
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• v.13 no.4
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• pp.225-231
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• 2000

Forcasting the future is a very important task in design situation analysis. To do this, the reduction of life style, the tendency of product differentiation and individuality should be considered along with such changes as cultural, economical and social trends. At the moment, industrial structure is being reorganized from centering around the manufacturing industry to the distribution industry and consumers. Consumers show the attitude of expressing their individualities on the basis of various tastes rather than standardization. The flow of information also has been changing rapidly from the former types of information provided by producers to the age when consumers pursue the objective and model of information. Therefore, we are able to say that picking up the trends around the streets becomes more important than ever. Accordingly, the objective of this study is to establish a system which is able to effectively carry out the trend analysis by a town watching method, the construction of a database with collected data, and its practical application on the web.