• 한국정보디스플레이학회:학술대회논문집
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• 2006.08a
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• pp.925-928
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• 2006

With the high sustain frequency at 250 kHz, a three-dimensional diagnostics of excited xenon atoms was investigated by the emission and absorption microscopic spectroscopy for plasma display panels, spatiotemporally. As a typical feature of the emissions, a broad discharge peak was observed on the temporal cathode and a sharp one was monitored on the anode, at the high frequency. However, the discharge starts from the cathode edge, actually, that is a discharge space on the floated address (or data) electrode. Spatially, the dense emission and absorption peak were observed in the discharge space between the sustain electrodes gap. Overall, the microdischarge at high sustain frequency showed priming dominant characteristics.

• Coupled systems mechanics
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• v.7 no.4
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• pp.421-440
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• 2018

In this study, a computational method for wall shear stress combined with an implicit direct-forcing immersed boundary method is presented. Near the immersed boundaries, the sub-grid stress is determined by a wall model in which the wall shear stress is directly calculated from the Lagrangian force on the immersed boundary. A coupling mathematical model of the transition process for a model Francis turbine comprising turbulent flow and rotating rigid guide vanes is established. The spatiotemporal distributions of pressure, velocity, vorticity and turbulent quantity are gained with the transient process; the drag and lift coefficients as well as other forces (moments) are also obtained as functions of the attack angle. At the same time, analysis is conducted of the characteristics of pressure pulsation, velocity stripes and vortex structure at some key parts of flowing passage. The coupling relations among the turbulent flow, the dynamical force (moment) response of blade and the rotating of guide vane are also obtained.

• Journal of Ocean Engineering and Technology
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• v.21 no.6
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• pp.59-63
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• 2007

This study discusses the spatiotemporal characteristics of the geomorphological changes in Gwangyang Bay. In this study, we analyzed four aerial photos and nautical charts. The geomorphological changes that have occurred over time were identified using an MGIS (Marine geographic information system) overlay analysis. As a result, we were able to identify the geomorphological changes that have resulted from the coastal development and fairway dredging of Gwangyang Bay. This paper demonstrates that the marine geographic information system can be effective in monitoring the geomorphological changes in coastal zones.

• Korean Journal of Remote Sensing
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• v.7 no.1
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• pp.45-67
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• 1991

An overview is given on stochastic techniques with which remotely sensed data may be used together with ground measurements for purposes of state estimation and prediction. They can explicitly account for spatiotemporal differences in measurement characteristics between ground measurements and remotely sensed data, and are suitable for highly variant space or space-time processes, such as atmosperic processes, which may be viewed as (containing) a random process. For state estimation of static ststems, optimal linear estimation is described. As alternatives, various co-kriging estimation techniques are also described, including simple, ordinary, universal, lognormal, disjunctive, indicator, and Bayesian extersion to simple and lognormal. For illustrative purposes, very simple examples of optimal linear estimation and simple co-kriging are given. For state estimation and prediction of dynamic system, distributed-parameter kalman filter is described. Issues concerning actual implemention are given, and with application potential are described.

• Korean Journal of Remote Sensing
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• v.35 no.4
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• pp.589-607
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• 2019

This paper presents a comprehensive overview of recent model developments and practical issues in spatial downscaling of coarse resolution satellite-derived products. First, theoretical aspects of spatial downscaling models that have been applied when auxiliary variables are available at a finer spatial resolution are outlined and discussed. Based on a thorough literature survey, the spatial downscaling models are classified into two categories, including regression-based and component decomposition-based approaches, and their characteristics and limitations are then discussed. Second, open issues that have not been fully taken into account and future research directions, including quantification of uncertainty, trend component estimation across spatial scales, and an extension to a spatiotemporal downscaling framework, are discussed. If methodological developments pertaining to these issues are done in the near future, spatial downscaling is expected to play an important role in providing rich thematic information at the target spatial resolution.

• Architectural research
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• v.24 no.1
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• pp.1-11
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• 2022

As the occurrence of a crime is dependent on different factors, their correlations are beyond the ordinary cognitive range. Owing to this limitation, systems face difficulty in correlating various factors, thereby requiring the assistance of artificial intelligence (AI) to overcome such limitations. Therefore, AI has become indispensable for crime prediction. Crimes can cause severe and irrevocable damage to a society. Recently, big data has been introduced for developing highly accurate models for crime prediction. Prediction of night crimes should be given significant consideration, because crimes primarily occur during nights, when the spatiotemporal characteristics become vulnerable to crimes. Many environmental factors that influence crime rate are applied for crime prediction, and their influence on crime rate may differ based on temporal characteristics and the nature of crime. This study aims to identify the environmental factors that influence sex and theft crimes occurring at night and proposes an artificial neural network (ANN) model to predict sex and theft crimes at night in random areas. The crime data of A district in Seoul for 12 years (2004-2015) was used, and environmental factors that influence sex and theft crimes were derived through multiple regression analysis. Two types of crime prediction models were developed: Type A using all environmental factors as input data; Type B with only the significant factors (obtained from regression analysis) as input data. The Type B model exhibited a greater accuracy than Type A, by 3.26 and 9.47 % higher for theft and sex crimes, respectively.

• ALGAE
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• v.37 no.1
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• pp.63-74
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• 2022

Perennial stipitate kelps are globally distributed and individual species can inhabit broad latitudinal ranges, expressing notably longevous persistence. Despite the foundational role kelps provide to their communities, little is known about the variability in persistence of the stipitate kelps at local spatial scales. We studied the population persistence of Eisenia arborea, a heat- and wave force-tolerant perennial stipitate kelp with a distributional range extending from British Columbia to south of the range limit of all other northeast Pacific kelps, in Baja California Sur, Mexico. Persistence characteristics for E. arborea among sites were compared and used to test the hypothesis that stand persistence varied at local spatial scales around Isla Natividad, a Pacific island off the Baja California peninsula with documented spatiotemporal environmental heterogeneity. Collected individuals around the island were "aged" using the previously validated age estimation technique of counting annual cortical dark rings. After detecting no significant differences among sites in the covariation between estimated ages for collected individuals and stipe length, we utilized in-situ population-level stipe length measurements to more rapidly predict age structures within six stands around the island. Predicted age structures, and associated stand densities, revealed persistence characteristics and density varied at local scales and a strong positive relationship existed between stand density and stand mean and maximum ages. We speculate that stands responded differently to deterministic influences (e.g., the 2014-2016 marine heatwave and / or competition with Macrocystis) resulting in heterogenous local persistence of this foundation species.

• The Journal of Korean Physical Therapy
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• v.35 no.3
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• pp.64-70
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• 2023

Purpose: This study investigated the influence of attention-demanding tasks on gait and measured differences in the temporal, spatial and kinematic characteristics between young healthy adults and elderly healthy adults. Methods: We recruited 16 healthy young adults and 15 healthy elderly adults in this study. All participants performed two cognitive tasks: a subtraction dual-task (SDT) and working memory dual-task (WMDT) during gait plus one normal gait. Using the LEGSys+ system, knee and hip-joint kinematic data during stance and swing phase and spatiotemporal parameter data were assessed in this study. Results: In the elderly adult group, attention-demanding tasks with gait showed a significant decrease in hip-joint motion during the stance phase, compared to the normal gait. Step length, stride length and stride velocity of the elderly adult group were significantly decreased in WMDT gait compared to normal gait (p<0.05). In the young adult group, kinematic data did not show any significant difference. However, stride velocity and cadence during SDT and WMDT gaits were significantly decreased compared to those of normal gait (p<0.05). Conclusion: We determined that attention-demanding tasks during gait in elderly adults can induce decreased hip-joint motion during stance phase and decreased gait speed and stride length to maintain balance and prevent risk of falling. We believe that understanding the changes during gait in older ages, particularly during attention-demanding tasks, would be helpful for intervention strategies and improved risk assessment.

• Journal of The Korean Society of Integrative Medicine
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• v.10 no.3
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• pp.233-246
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• 2022

Purpose : The study aims to determine the effects of virtual and non-virtual realities in a normal person's mirror walk on gait characteristics. Methods : Twenty male adults (Age: 27.8 ± 5.8 years) participated in the study. Reflection markers were attached to the subjects for motion analysis, and they walked in virtual reality environments with mirrors by wearing goggles that showed them the virtual environments. After walking in virtual environments, the subjects walked in non-virtual environments with mirrors a certain distance away after taking a 5 min break. To prevent the order effect caused by the experiential difference of gait order, the subjects were randomly classified into groups of 10 and the order was differentiated. During each walk, an infrared camera was used to detect motion and the marker positions were saved in real time. Results : Comparison between the virtual and non-virtual reality mirror walks showed that the movable range of the leg joints (ankle, knee, and hip joints), body joints (sacroiliac and atlantoaxial joints), and arm joints (shoulder and wrist joints) significantly differed. Temporal characteristics showed that compared to non-virtual gaits, the virtual gaits were slower and the cycle time and double limb support time of virtual gaits were longer. Furthermore, spacial characteristics showed that compared to non-virtual gaits, virtual gaits had shorter steps and stride lengths and longer stride width and horizontally longer center of movement. Conclusion : The reduction in the joint movement in virtual reality compared to that in non-virtual reality is due to adverse effects on balance and efficiency during walking. Moreover, the spatiotemporal characteristics change based on the gait mechanisms for balance, exhibiting that virtual walks are more demanding than non-virtual walks. However, note that the subject group is a normal group with no abnormalities in gait and balance and it is unclear whether the decrease in performance is due to the environment or fear. Therefore, the effects of the subject group's improvement and fear on the results need to be analyzed in future studies.

• Journal of the Korean Society for Marine Environment & Energy
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• v.11 no.2
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• pp.78-85
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• 2008

We estimated the pollutant loads for the last 3 years based on the daily discharge at the Nakdong River dam(barrage) and spatiotemporal characteristics of seawater quality in the Nakdong river estuary to investigate the correlation between the pollutant load inflow rate and seawater quality. The main results from this research are summarized as follows. (1) The total discharge at the Nakdong River dam dam the last 11 years has been $224,576.8{\times}10^6m^3/day$. The discharge figures show that the maximum discharge occurs in August with $52,634.2{\times}10^6 m^3/day$ (23.4% of the year's volume), followed by July and Sep. in that order with 23.1 and 17%, respectively. (2) The pollutant load influx from the Nakdong River dam was composed of 307,591.3COD-kg/day, 128.746.1 TN-kg/day, and 107,625.8 TP-kg/day. (3) The surface temperature in the Nakdong River estuary was about $2.137^{\circ}C$ higher than that of the lower layer. The salinity of the lower layer was 2.209%o higher than that of the ocean surface. The salinity of the ocean surface decreased by up to 19.593%o due to the inflow of the discharge at the Nakdong River dam. (4) DO, COD, TN, and SS concentration levels tended to be higher at the ocean surface than in lower layers, whereas the reverse was true for TP. (5) The water mass at the ocean's surface and in the lower layers during the drought and flood seasons tended to be separated by the difference in densities due to the freshwater inflow.