• KSII Transactions on Internet and Information Systems (TIIS)
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• 제15권7호
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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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• 제38권1호
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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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• 제44권1호
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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.

• 대한조선학회논문집
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• 제58권6호
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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.

• 한국산업융합학회 논문집
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• 제24권6_2호
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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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• 제10권1호
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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.

• 한국지하수토양환경학회지:지하수토양환경
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• 제28권6호
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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.

• Nuclear Engineering and Technology
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• 제56권10호
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• pp.4397-4403
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• 2024

The multi-dimensional thermal-hydraulic phenomena in the downcomer of advanced pressurized water reactor with direct vessel injection system are the key points for the safety analysis during a loss of coolant accident. In order to improve the accuracy of LOCUST code for the predictions of thermal-hydraulic phenomena in downcomer region, some newly correlations have been implemented into LOCUST code. The wall friction model of LOCUST code was modified based on the correlations which developed by Yang. The interfacial friction models in LOCUST code have been modified as Hibiki-Ishii correlations. In addition, in order to simulate the upward flow of recirculation flow in downcomer region, the Kinoshita-Hibiki correlations have been also implemented into LOCUST code for better simulating the recirculation flow in downcomer region. The modified code was validated with experimental data of DOBO facility. Five tests of DOBO facility have been calculated by LOCUST, and the calculated axial void fraction distributions have been compared with the measurements. The results show that the modified LOCUST with new correlations of distribution parameter and drift velocity shows better accuracy than the original code. The deviations of the modified LOCUST code are less than the original code and are almost within ±20 %.

• 유통과학연구
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• 제7권2호
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• pp.89-119
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• 2009

본 연구의 목적은 충성고객에서부터 불만고객에 이르기까지 다양한 고객의 소리(VOC)를 통하여 유통업체들이 서비스마케팅을 극대화시킬 수 있는 방안을 도출하고 적절한 VOC시스템의 구축방안을 제시하고자 한다. 연구의 범위는 유통업체로 국한하였으며, 여러 VOC 채널 중에서 인터넷 게시판을 대상으로 하였다. 실증적인 연구를 위해 유통업체 5개사(社)의 홈페이지 상에 민원을 제기하고 나서 처리되는 과정을 사례로써 조사하였다. 그리고 고객만족도 조사는 유통업체 A사(社)의 ○○점을 대상으로 설문조사를 실시하였다. 본 연구를 통해 나타난 결과는 다음과 같다. 첫째, 소비자의 감성을 자극하는 신속하고 성실한 답변은 기업의 이미지를 긍정적으로 전환시켰다. 둘째, 연령대와 성별로 VOC채널에 대한 선호도를 달리하였다. 30대 이하와 40대 이상 각기 다른 채널을 도구로 감성을 자극해야 하며 남자에 비해 여자는 대다수 전화로 하는 즉각적이면서도 자신의 스토리를 들어주길 원하는 스타일이었다. 셋째, 소비자 트렌드 변화에 따라 쌍방향커뮤니케이션이 가능한 VOC시스템을 위해 감성 네트워크 시스템을 구축해야 한다. 따라서 본 연구에서는 현장에서 접목할 수 있는 VOC개선방안을 제시함으로써 실질적인 현장위주, 고객위주의 실천과제를 도출해 보았다.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2004년도 추계학술대회
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• pp.211-218
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• 2004

WAM 모형은 대양의 파랑추산에 있어서 높은 정밀도를 가지고 있으면서도 타 모형에 비해 상대적으로 간결한 구조를 가지고 있어 국내외 많은 연구자들이 널리 활용하고 있으나, 모형의 특성상 심해${\cdot}$광역조건과 더불어 비교적 큰 격자에 적합하도록 설계되어 있고 파향의 격자 분한 방법으로 언해 경우에 따라서는 예기치 못하는 계산 결과를 산출하기도 한다. 본 연구에서는 WAM Cycle 4 모형을 대상으로 이 같은 문제점을 상세히 검토하고 관련 내용을 수정하여 천해${\cdot}$ 상세 해역에 대한 적용성을 확장하였으며, 수정된 WAM 모형은 이어도 해양과학기지에서 관측한 2003년 9월 한 달 동안의 정밀 파랑관측 자료를 토대로 검정하여 그 타당성을 확인하였다.