• Human Ecology Research
• /
• v.54 no.6
• /
• pp.565-574
• /
• 2016

This research examined the trajectories of peer rejection in preschool children. This study also investigated the gender differences in the intercept and slope of the trajectories for peer rejection along with the influences of aggression, withdrawal and language ability on the trajectories of peer rejection. A latent growth curve model investigated peer rejection in 3 to 5 year olds. Three hundred and thirteen 3-year-old children were recruited from five preschools and 14 daycare centers. The children's language ability was measured by a Wechsler Preschool and Primary Scale of intelligence verbal test and teachers completed measurements for aggression and withdrawal. A peer nomination inventory was used to assess peer rejection. Children were asked to nominate three classmates who they do not like to play with. The research findings showed that peer rejection decreased during the preschool years. Compared with girls, boys showed higher levels of peer rejection and a slower change rate of peer rejection. Girls who were aggressive showed high levels of peer rejection and a slow change rate of peer rejection. Moreover, girls who had a high levels language showed low levels of peer rejection and a slow change rate of peer rejection. These findings imply that language ability could be a protective factor of peer rejection for girls.

• Journal of the Korea Institute of Military Science and Technology
• /
• v.14 no.3
• /
• pp.397-404
• /
• 2011

The aerodynamic characteristics of a separated captive body in flow field around aircraft are studied to observe aerodynamic stability for safe separation from aircraft. Since the captive body separated from aircraft is initially exposed to unsteady flow pattern, the change of aerodynamic forces and moments should be measured to analyze how the flow pattern affects on the captive body at the vicinity of aircraft. Aerodynamic forces and moments of the separated captive body are measured at selected positions along predictable dropping trajectories. The measuring trajectories, generated by the free drop test of the dropping model in the wind tunnel, are consisted of 9 possible lines by free dropped trajectories. Experimental results show that the aerodynamic forces and moments are significantly varied with the distance between the captive body and aircraft. In conclusion, the change of aerodynamic characteristics within flow field around aircraft should be considered to simulate trajectories of the separated captive body from aircraft.

• Journal of the Ergonomics Society of Korea
• /
• v.32 no.3
• /
• pp.245-252
• /
• 2013

Objective: This paper analyzes the changes on stride parameters, joint angles, and trajectories of the body parts due to high heels during walking and explains the causal relationship between the changes and high heels. Background: This study aims to indicate the comprehensive gait changes by high heels on the whole body for women wearing high heels and researchers interested in high-heeled walking. Method: The experiment was designed in which two different shoe heel heights were used for walking (1cm, 9.8cm), and twelve women participated in the test. In the experiment, 35 points on the body were tracked to extract the stride parameters, joint angles, and trajectories of the body parts. Results: Double support time increased, but stride length decreased in high-heeled walking. The knee inflexed more at stance phase and the spine rotation became more severe. The trajectories of the pelvis, the trunk and the head presented outstanding fluctuations in the vertical direction. Conclusion: The double support time and the spine rotation were changed to compensate instability by high heels. Reduced range of motion of the ankle joint influenced on the stride length, the knee flexion, and fluctuations of the body parts. Application: This study can provide an insight of the gait changes by high heels through the entire body.

• KIPS Transactions on Software and Data Engineering
• /
• v.4 no.10
• /
• pp.439-446
• /
• 2015

Recently, semantic trajectories which combine GPS positions and POIs(Point of Interests) become more popular in order to expand location based services. To construct semantic trajectories, the existing algorithms exploit the extent information of POIs described as polygons and find overlapping regions between GPS positions and the extents. However, the algorithms are not applicable in the condition where the extent information is not provided such as in Google Map, Naver Map, OpenStreetMap and most of the open geographic information systems. In this paper, we provide a novel algorithm to construct semantic trajectories only with GPS positions and POI points but without POI extents.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.13 no.7
• /
• pp.3599-3619
• /
• 2019

In human activity recognition system both static and motion information play crucial role for efficient and competitive results. Most of the existing methods are insufficient to extract video features and unable to investigate the level of contribution of both (Static and Motion) components. Our work highlights this problem and proposes Static-Motion fused features descriptor (SMFD), which intelligently leverages both static and motion features in the form of descriptor. First, static features are learned by two-stream 3D convolutional neural network. Second, trajectories are extracted by tracking key points and only those trajectories have been selected which are located in central region of the original video frame in order to to reduce irrelevant background trajectories as well computational complexity. Then, shape and motion descriptors are obtained along with key points by using SIFT flow. Next, cholesky transformation is introduced to fuse static and motion feature vectors to guarantee the equal contribution of all descriptors. Finally, Long Short-Term Memory (LSTM) network is utilized to discover long-term temporal dependencies and final prediction. To confirm the effectiveness of the proposed approach, extensive experiments have been conducted on three well-known datasets i.e. UCF101, HMDB51 and YouTube. Findings shows that the resulting recognition system is on par with state-of-the-art methods.

• Journal of Korean Academy of Nursing
• /
• v.50 no.6
• /
• pp.822-836
• /
• 2020

Purpose: This study aimed to identify latent classes of behavioral problem trajectories in children with allergic diseases and investigate their predictors. Methods: This study used data from the 5th to 7th Panel Study of Korean Children. The participants included 840 children aged 4~6 years with allergic diseases. Statistical analyses were conducted using latent class growth analysis and multinomial logistic regression. Results: The trajectories of both internalizing and externalizing behavioral problems in children with allergic diseases were classified into five groups, that is deteriorative, recovering, changing 1 (decreasing-increasing), changing 2 (increasing-decreasing), and low state persistent group. For the internalizing behavioral problems, predictors were temperament, father's education, family interaction, and disconnection in peer interaction. For the externalizing behavioral problems, predictors child's gender, temperament, marital conflict, parenting stress, family interaction, and parenting environment. Conclusion: Deteriorative group has high-risk behavioral problems in children with allergic diseases. We suggest to provide interventions considering latent problem trajectories based on ecological environments for allergic children.

• Journal of Platform Technology
• /
• v.11 no.1
• /
• pp.52-59
• /
• 2023

The importance of spatio-temporal trajectories for contact tracing has increased due to the recent COVID-19 pandemic. Spatio-temporal trajectories store time and spatial data of moving objects. In this paper, I propose query processing for spatio-temporal trajectories of moving objects. The spatio-temporal trajectory model of moving objects has point type spatial data for storing locations and timestamp type temporal data for time. A trajectory query is a query to search for pairs of users who have been in close contact by boarding the same bus. To process the trajectory query, I use the Geolife dataset provided by Microsoft. The proposed trajectory query processing method divides trajectory data by date and checks whether users' trajectories were nearby for each date to generate information about contacts as the result.

• Research in Community and Public Health Nursing
• /
• v.33 no.1
• /
• pp.74-83
• /
• 2022

Purpose: The purpose of this study was to identify latent classes of health-related quality of life trajectories in middle-aged women and investigate predictors for latent classes. Methods: This study utilized data from the 2^nd, the 4^th to the 7^th Korean Longitudinal Survey of Women & Families. The subjects included 1,351 women aged 40~45 years. The data was analyzed using latent class growth analysis and logistic regression. Results: Two trajectories were identified for health-related quality of life in middle-aged women; 'persistently good' and 'increasing' groups. Predictors for the 'increasing' group were lower economic status, higher depression, and lower perceived health status. Conclusion: This study showed that characteristics of the individual, symptom status, and health perceptions were associated with health-related quality of life in middle-aged women. It is necessary to provide effective intervention for latent classes of health-related quality of life trajectories based on physical, mental, and social factors.

• Journal of Korea Multimedia Society
• /
• v.13 no.8
• /
• pp.1128-1141
• /
• 2010

This paper proposes a method of moving object detection in crowded scene using clustered trajectory. Unlike previous appearance based approaches, the proposed method employes motion information only to isolate moving objects. In the proposed method, feature points are extracted from input frames first and then feature tracking is followed to create feature trajectories. Based on an assumption that feature points originated from the same objects shows similar motion as the object moves, the proposed method detects moving objects by clustering trajectories of similar motions. For this purpose an energy function based on spatial proximity, motion coherence, and temporal continuity is defined to measure the similarity between two trajectories and the clustering is achieved by minimizing the energy function in CRFs (conditional random fields). Compared to previous methods, which are unable to separate falsely merged trajectories during the clustering process, the proposed method is able to rearrange the falsely merged trajectories during iteration because the clustering is solved my energy minimization in CRFs. Experiment results with three different crowded scenes show about 94% detection rate with 7% false alarm rate.

• Journal of KIISE:Databases
• /
• v.30 no.1
• /
• pp.14-26
• /
• 2003

Moving objects' trajectories play an important role in indexing video data on their content and semantics for content-based video retrieval. In this paper, we propose new similar sub-trajectory retrieval schemes based on k-warping algorithm for efficient retrieval on moving objects' trajectories in video data. The proposed schemes are fixed-replication similar sub-trajectory retrieval(FRSR) and variable-replication similar sub-trajectory retrieval(VRSR). The former can replicate motions with a fixed number for all motions being composed of the trajectory. The latter can replicate motions with a variable number. Our schemes support multiple properties including direction, distance, and time interval as well as a single property of direction, which is mainly used for modeling moving objects' trajectories. Finally, we show from our experiment that our schemes outperform Li's scheme(no-warping) and Shan's scheme(infinite-warping) in terns of precision and recall measures.