• Journal of Korean Society for Atmospheric Environment
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• v.33 no.2
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• pp.174-183
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• 2017

The background level and timely variation characteristics of atmospheric $^{222}Rn$ concentrations have been evaluated by the real time monitoring at Gosan site of Jeju Island, Korea, during 2008~2015. The average concentration of atmospheric radon was $2,480mBq\;m^{-3}$ for the study period. The cyclic seasonality of radon was characterized such as winter maximum and summer minimum, consistent with the reduction in terrestrial fetch going to summer. On monthly variations of radon, the mean concentration in October was the highest as $3,041mBq\;m^{-3}$, almost twice as that in July ($1,481mBq\;m^{-3}$). The diurnal radon concentrations increased throughout the nighttime approaching to the maximum ($2,819mBq\;m^{-3}$) at around 7 a.m., and then gradually decreased throughout the daytime by the minimum ($2,069mBq\;m^{-3}$) at around 3 p.m. The diurnal radon cycle in winter showed comparatively small amplitude due to little variability in atmospheric mixing depth, conversely, large amplitude was observed in summer due to relatively a big change in atmospheric mixing depth. The cluster back-trajectories of air masses showed that the high radon events occurred by the predominant continental fetch over through Asia continent, and the radon concentrations from China continent were about 1.9 times higher on the whole than those from the North Pacific Ocean. The concentrations of $PM_{10}$ also increased in proportion to the high radon concentrations, showing a good linear correlation between $PM_{10}$ and radon concentrations.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.3
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• pp.391-399
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• 2017

The purpose of this study is to verify the causal relationship between social withdrawal and peer alienation among Korean children. The survey study participants were 2,110 children in 2nd, 3rd, 4th, and 5th grades. The 5-year longitudinal data (Korean Child and Youth Panel Survey; KCYPS) of 1st grade elementary school student cohort was used. Latent Growth Modeling was applied to analyze the causality over time of social withdrawal and peer isolation. The results revealed that the trajectories of children's social withdrawal decreased over time. Children's social withdrawal showed significant individual differences in terms of initial value and rates of change. The initial value and slope of children's social withdrawal had an effect on the peer alienation in the 3rd grade; however, there was no significant effect on the peer alienation in the 5th grade.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.49 no.10
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• pp.829-839
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• 2021

Autonomous system for UAVs has a capability to decide an appropriate current action to achieve the goal based on the ultimate mission goal, context of mission, and the current state of the UAV. We propose a decision-making system that has an ability to operate ISR mission autonomously under the realistic limitation such as low altitude operation with high risk of terrain collision, a set of way points without change of visit sequence not allowed, and position uncertainties of the objects for the mission. The proposed decision-making system is loaded to a Hardware-In-the-loop Simulation environment, then tested and verified using three representative scenarios with a realistic mission environment. The flight trajectories of the UAV and selected actions via the proposed decision-making system are presented as the simulation results with discussion.

• 한국HCI학회:학술대회논문집
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• 2009.02a
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• pp.531-537
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• 2009

When creating large crowds, it is unavoidable that the models and motions of many characters will be cloned. McDonnell implemented experiments focus on appearance and motion of characters to test user perception of crowds. As a result, appearance clones were easier to perceive than motion clones. In this paper, I researched about relation between character cloning and user perception for real-time game environment expanding McDonnell's research. This paper focuses on the way to recognition of multiple clones in dramatic environment free to change view point and has crowds move to every directions by trajectories. In particular, this paper shows the possibility of character diversification applied various shapes, colors and patterns to game item have important elements for game characters. Also, I suggests range of distances between clones by a series of experiments of user perception for clones's moving direction and distance.

• Journal of KIISE:Databases
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• v.31 no.3
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• pp.219-231
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• 2004

Recently, together with increasing use of multimedia data, many works on moving objects in video databases have been made. Moving objects change visual features and spatial positions with the lapse of time in video data. And they arc related to the other objects or events. In this paper, we propose a new modeling and various query types of moving objects for content based retrieval in video databases. The proposed modeling represents visual features, moving trajectories and semantic contents related to objects. Therefore, it allows to process various query types. And we propose various query operators for the retrieval types. To show the superiority of our modoling, we implement the retrieval systems and compare it with the existing methods in terms of the supporting query types. The proposed method supports various query types and improves the efficiency of the query processing over the existing methods.

• Journal of the Korean Society of Propulsion Engineers
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• v.4 no.4
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• pp.78-86
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• 2000

The objective of this research is to understand the characteristics of a nonpremixed, turbulent, hydrogen jet flame which is stabilized in Mach 1.8 coflowing air flows. In order to investigate the flame structure, flame lengths and fuel trajectories were measured by using direct photography, acetone PLIF, Mie scattering techniques, and numerical simulation. Effect of increasing air velocity was investigated when fuel velocity is fixed. The subsonic flame length was decreased drastically, however the supersonic flame length was increased slowly Then the change of flame blow out characteristics was observed as varying fuel nozzle lip thickness. The flame stability can be increased when fuel nozzle lip thickness was increased, which indicates that the minimum fuel lip thickness ratio is required for the stable supersonic flames. Also, it is found that fuel jet is blocked by high pressure zone and low scattering zone is made. Then the fuel that was moving along the recirculation zone had longer residence time within the supersonic flames, which made partially premixed zone.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.27 no.2
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• pp.79-93
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• 2015

Three-dimensional structures of large ocean rings in the Gulf Stream region are investigated using the HYbrid Coordinate Ocean Model (HYCOM). Numerically simulated flow structures around four selected cyclonic and anticyclonic rings are compared with two different horizontal resolutions: $1/12^{\circ}$ and $1/48^{\circ}$. The vertical distributions of Lagrangian Coherent Structures (LCSs) are analyzed using Finite Size Lyapunov Exponent (FSLE) and Okubo-Weiss parameters (OW). Curtain-shaped FSLE ridges are found in all four rings with extensions of surface ridges throughout the water columns, indicating that horizontal stirring is dominant over vertical motions. Near the high-resolution rings, many small-scale flow structures with size O(1~10) km are observed while these features are rarely found near the low-resolution rings. These small-scale structures affect the flow pattern around the rings as flow particles move more randomly in the high-resolution models. The dispersion rates are also affected by these small-scale structures as the relative horizontal dispersion coefficients are larger for the high-resolution models. The absolute vertical dispersion rates are, however, lower for the high-resolution models, because the particles tend to move along inclined eddy orbits when the resolution is low and this increases the magnitude of absolute vertical dispersion. Since relative vertical dispersion can reduce this effect from the orbital trajectories of particles, it gives a more reasonable magnitude range than absolute dispersion, and so is recommended in estimating vertical dispersion rates.

• Korean Journal of Social Welfare Studies
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• v.48 no.4
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• pp.157-185
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• 2017

This study aimed to explore the trajectories of economic preparations for the aging among people with physical disabilities and to identify the determinants according to the Andersen model. For this study, data were drawn from Panel Survey of Employment for the Disabled (PSED). A total of 1,847 samples were used from the second to the eighth wave. Latent class growth model was conducted to explore the longitudinal change classes for the disabled, and the multinominal logistic regression analysis was conducted to examine the influence of the determinants. As a result, four classes were identified: preparation decrease group, continuous non-preparation group, preparation increase group, and continuous preparation group. Each group was found to be associated deferentially with education level, family income, socioeconomic status, employment, home ownership, national basic livelihood security recipient status, and ADL. These findings proposed the practical and political implications for the strategies concerned with facilitating the economic preparations for the aging among the disabled.

• 동북아역사논총
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• no.60
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• pp.196-227
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• 2018

The issues of this study are as follows. First, I will examine the overall situation and transition trends of Tibetan research in Taiwan since the modern period, and examine the development and trends of Tibetan history research in Taiwan. Secondly, in order to satisfy the above, we will analyze trends of Taiwan's major Tibetan research institutes and scholars, and trace their trends and their trajectories. Third, the trend of Tibetan research in Taiwan may be a useful indicator for us to analyze research methods and trends of Taiwanese scholars. If there is a flow of features and transitions, the text will explore the reason. Fourth, one of the implications of this study is that it can trigger an understanding of locality in the structure of the central region, the Han Chinese minority, and the possession and distribution of academic reasoning. In other words, it should be noted that even though the same Tibetan research is conducted, China is in the position of the vested right to distribute 226 | 동북아역사논총 60호the central or ownership, while Taiwan has historical and territorial characteristics that deviate from such a gaze and attitude. Taiwan may be sensitive to the vertical concept understood as a change in the relationship between the state and the center, or whether it is applicable to Tibetan research. If there is such an academic climate, I would like to consider suggestions for us. This may provide a direction to view the academic issues of a few scholars, or even the domestic academic world as an independent object of more specific academic research.

• Survey Research
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• v.18 no.4
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• pp.25-59
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• 2017

The current study investigated how elderly husbands and wives' marital satisfaction and depression change over time and examined how changes in marital satisfaction account for changes in depression between and within the dyads. The longitudinal dyadic data from the first wave(2006) to the fifth wave(2014) of the Korean Longitudinal Study of Aging(KLoSA), collected by the Korea Employment Information Service, were used for the analyses. Because husbands and wives are interdependent within couples, we applied statistical models for dyadic data. The dyadic growth model(DGM) was used to model the trajectories of marital satisfaction and depressive symptoms. In order to analyze the association of these growth factors, we proposed the dyadic growth actor-partner interdependence model(DG-APIM) and applied the model to the data. The results showed that on average the husbands' marital satisfaction was higher but decreased faster over the course of the study than the wives'. It also showed that the average depression of the husbands was lower than that of the wives but the husbands' depression increased faster than the wives' over the course of the study. The variance of the averages of husbands' (wives's) depression was accounted for by that of wives'(husbands') marital satisfaction, showing a partner effect. The variance of the slopes of husbands'(wives') depression was accounted for by that of marital satisfaction of themselves, showing an actor effect. The results showed that there is a longitudinal interdependence between husbands and wives' marital satisfaction and depression and supported the marital discord model of depression.