• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.50 no.1
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• pp.39-45
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• 2022

In this paper, we propose methods to improve image-based auto-focus that can compensate for drawbacks of traditional auto-focus control. When adjusting the focus, there is a problem that the focus window cannot be set to the same position if the camera's LOS is not directed at the same location and flow or shake. To address this issue, we applied image tracking techniques to improve optimal focus localization accuracy. And also, although the same focus value should be calculated at the same focus step, but different values can be calculated by camera's fine shaking or image disturbance due to atmospheric scattering. To tackle this problem a SAFS (Stable Adjacency Frame Selection) has been proposed. As a result of this study, our proposed methodology shows more accurate than traditional methods in terms of finding best focus position.

• Journal of the Korea Computer Graphics Society
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• v.27 no.5
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• pp.55-61
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• 2021

The character motion control based on physics simulation using reinforcement learning continue to being carried out. In order to solve a problem using reinforcement learning, the network structure, hyperparameter, state, action and reward must be properly set according to the problem. In many studies, various combinations of states, action and rewards have been defined and successfully applied to problems. Since there are various combinations in defining state, action and reward, many studies are conducted to analyze the effect of each element to find the optimal combination that improves learning performance. In this work, we analyzed the effect on reinforcement learning performance according to the state representation, which has not been so far. First we defined three coordinate systems: root attached frame, root aligned frame, and projected aligned frame. and then we analyze the effect of state representation by three coordinate systems on reinforcement learning. Second, we analyzed how it affects learning performance when various combinations of joint positions and angles for state.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.22 no.2
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• pp.133-146
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• 2023

Traffic states in urban areas are essential to implement effective traffic operation and traffic control. However, installing traffic sensors on numerous road sections is extremely expensive. Accordingly, estimating the traffic state using a vehicle-mounted camera, which shows a high penetration rate, is a more effective solution. However, the previously proposed methodology using object tracking or optical flow has a high computational cost and requires consecutive frames to obtain traffic states. Accordingly, we propose a method to detect vehicles and lanes by object detection networks and set the region between lanes as a region of interest to estimate the traffic density of the corresponding area. The proposed method only uses less computationally expensive object detection models and can estimate traffic states from sampled frames rather than consecutive frames. In addition, the traffic density estimation accuracy was over 90% on the black box videos collected from two buses having different characteristics.

• Smart Media Journal
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• v.11 no.9
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• pp.64-74
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• 2022

A number of studies related to underwater robots are being conducted to utilize marine resources. However, unlike ordinary drones, underwater robots have a problem that it is not easy to locate because the medium is water, not air. The monitoring and positioning program of underwater robots, an existing study for identifying underwater locations, has difficulty in locating and monitoring in small spaces because it aims to be utilized in large spaces. Therefore, in this paper, we propose a three-dimensional positioning program for continuous monitoring and command delivery in small spaces. The proposed program consists of a multi-dimensional positioning monitoring function and a ability to control the path of travel through a three-dimensional screen so that the depth of the underwater robot can be identified. Through the performance evaluation, a robot underwater could be monitored and verified from various angles with a 3D screen, and an error within the assumed range was verified as the difference between the set path and the actual position is within 6.44 m on average.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.59 no.1
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• pp.44-54
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• 2023

In this study, the second-order Nomoto's nonlinear expansion model was implemented as a Tagaki-Sugeno fuzzy model based on the heading angular velocity to design the automatic steering system of a ship considering nonlinear elements. A Tagaki-Sugeno fuzzy PID controller was designed using the applied fuzzy membership functions from the Tagaki-Sugeno fuzzy model. The linear models and fuzzy membership functions of each operating point of a given nonlinear expansion model were simultaneously tuned using a genetic algorithm. It was confirmed that the implemented Tagaki-Sugeno fuzzy model could accurately describe the given nonlinear expansion model through the Zig-Zag experiment. The optimal parameters of the sub-PID controller for each operating point of the Tagaki-Sugeno fuzzy model were searched using a genetic algorithm. The evaluation function for searching the optimal parameters considered the route extension due to course deviation and the resistance component of the ship by steering. By adding a penalty function to the evaluation function, the performance of the automatic steering system of the ship could be evaluated to track the set course without overshooting when changing the course. It was confirmed that the sub-PID controller for each operating point followed the set course to minimize the evaluation function without overshoot when changing the course. The outputs of the tuned sub-PID controllers were combined in a weighted average method using the membership functions of the Tagaki-Sugeno fuzzy model. The proposed Tagaki-Sugeno fuzzy PID controller was applied to the second-order Nomoto's nonlinear expansion model. As a result of examining the transient response characteristics for the set course change, it was confirmed that the set course tracking was satisfactorily performed.

• Journal of Environmental Science International
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• v.31 no.3
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• pp.219-226
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• 2022

This study was conducted to investigate the response of the human body to stress induced by wall recording of subway stations in the city center. The experiment was conducted as a simulation exercise, and six images were selected and produced based on Subway Line 2, a representative underground space in Seoul. The study participants included 24 male and female college students. A three-minute experiment was conducted, during which the participants were shown the control image and green wall image once each. To measure psychological status, the following measurement indicators were used: Semantic Differential, Positive Affect and Negative Affect Schedule and State-Trait Anxiety Inventory. Physiological changes were investigated by tracking participants' heart rate and blood pressure. Results showed that parasympathetic and sympathetic nerves were activated in the presence of the green wall in the subway station. The psychological evaluation analysis revealed that negative affect toward underground space decreased, while positive affect increased. This study found that the green wall in subway stations has a stable effect on the human body, both psychologically and physiologically. In the future, green walls in underground spaces can be used to reduce psychological stress and increase physiological relaxation.

• SUVANNABHUMI
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• v.6 no.2
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• pp.3-18
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• 2014

With natural resources-terrestrial or coastal-fastly diminishing, governments are now resorting to biodiversity conservation, fast-tracking the introduction of new legislations, as well as the amendment of existing ones, and laying out programs that interpret existing practices and research agendas. This paper examines how biodiversity conservation-in addition to eco-tourism-has become an important symbol of the modernizing state of Sabah, Malaysia. It further examines the effects of biodiversity conservation on state and community management of natural resources, with particular reference to the management of natural resources by the indigenous peoples of Sabah. Citing case studies and focusing on a forest community at Kiau Nuluh, in the district of Kota Belud, Sabah, this paper evaluates strategies used by indigenous groups to maintain access and control over the management of natural resources-and by implication to livelihoods-via ecotourism, making creative alliances with non-government organisations as well as forging cooperation with government agencies which act as custodians of these resources. For a majority of indigenous groups however, the practice of biodiversity conservation has meant reduced and controlled access to natural resources, considering the fundamental issue of the lack of security of tenure to the land claimed under customary rights. New initiatives at recognizing Indigenous and Community Conserved Areas (ICCAs) by international conservation groups provide a means for tenure recognition, for a price, of course. The recognition of ICCAs also faces obstacles arising from developmentalist ideology which upholds that forests are valuable only when converted to other land use, and not left to stand for their intrinsic value.

• PNF and Movement
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• v.21 no.3
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• pp.327-335
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• 2023

Purpose: Cerebellar injury can be caused by a variety of factors, including trauma, stroke, and tumor. Cerebellar injury can manifest in different clinical symptoms and signs depending on the size and location of the injury. The purpose of this study was to examine and compare the recovery patterns of each motor function by tracking the motor levels of patients with cerebellar injury. Methods: This study recruited 11 patients with quadriplegia resulting from cerebellar injury. The motricity index (MI), modified Brunnstrom classification (MBC), and functional ambulation category (FAC) methods were used to evaluate motor levels. The motor function evaluation was performed immediately after the onset of the condition and at intervals of one month, two months, and six months after onset. Results: The MI values of the upper and lower extremities and hand function (MBC) indicated severe paralysis in the early stages of onset. Compared to the onset time, significant motor function recovery was observed after 1, 2, and 6 months (p < 0.05). In contrast, there was no significant pattern of recovery between 1, 2, and 6 months after onset (p > 0.05). FAC indicated showed significant recovery at one month compared to onset (p<0.05), and there was also a significant difference between 1 and 2 months (p < 0.05). On the other hand, there was no significant difference in FAC between 2 and 6 months (p > 0.05). Conclusion: Patients with cerebellar injury showed significant recovery in functions related to muscle strength and voluntary muscle control one month after onset and gradually recovered further over the next six months. On the other hand, gait function, which is closely related to balance, showed a relatively slow recovery pattern from the beginning of the disease to the six month follow-up.

• Journal of Cardiovascular Imaging
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• v.30 no.4
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• pp.279-289
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• 2022

BACKGROUND: In many cardiovascular disorders, the contractile performance of the right ventricle (RV) is the primary determinant of prognosis. For evaluating RV volumes and function, 4 dimensional (4D)-echocardiography has become common. This research used 2D and 4D modalities to assess RV contractile performance in hypertensive patients. METHODS: A total of 150 patients with essential hypertension were enrolled in this study, along with 75 age and sex-matched volunteers. Clinical evaluation and echocardiographic examination (including M-mode, tissue Doppler imaging, and 2D speckle tracking) were conducted on all participants. RV volumes, 4D-ejection fraction (EF), 4D-fractional area change (FAC), 4D-tricuspid annular plane systolic excursion (TAPSE), 4D-septal and free wall (FW) strain were all measured using 4D-echocardiography. RESULTS: Hypertensive patients showed 2D-RV systolic and diastolic dysfunction (including TAPSE, 2D-right ventricular global longitudinal strain, RV-myocardial performance index and average E/EaRV) and 4D-RV impairment (including right ventricular EF, FAC, RV strain and TAPSE, right ventricular end-diastolic volume and right ventricular end-systolic volume) compared to the control group. We verified the prevalence of RV systolic dysfunction in hypertension patients using the following parameters: 1) 15% of them had 2D-TAPSE < 17 mm vs. 40% by 4D-TAPSE; 2) 25% of them had 2D-GLS < 19% vs. 42% by 4D-septal strain and 35% by 4D FW strain; 3) 35% of hypertensive patients had 4D-EF < 45%; and finally; 4) 25% of hypertensive patients had 2D-FAC < 35% compared to 45% by 4D-FAC. CONCLUSIONS: The incidence of RV involvement was greater in 4D than in 2D-modality trans-thoracic echocardiography. We speculated that 4D-echocardiography with 4D-strain imaging would be more beneficial for examining RV morphology and function in hypertensive patients than 2D-echocardiography, since 4D-echocardiography could estimate RV volumes and function without making geometric assumptions.

• Journal of the Korean Association of Geographic Information Studies
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• v.23 no.2
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• pp.53-69
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• 2020

The increase of the impermeable area due to industrialization and urban development distorts the hydrological circulation system and cause serious stream drying phenomena. In order to manage this, it is necessary to develop a technology for impact assessment of stream drying phenomena, which enables quantitative evaluation and prediction. In this study, the cause of streamflow reduction was assessed for dam and weir watersheds in the five major river basins of South Korea by using distributed hydrological model DrySAT-WFT (Drying Stream Assessment Tool and Water Flow Tracking) and GIS time series data. For the modeling, the 5 influencing factors of stream drying phenomena (soil erosion, forest growth, road-river disconnection, groundwater use, urban development) were selected and prepared as GIS-based time series spatial data from 1976 to 2015. The DrySAT-WFT was calibrated and validated from 2005 to 2015 at 8 multipurpose dam watershed (Chungju, Soyang, Andong, Imha, Hapcheon, Seomjin river, Juam, and Yongdam) and 4 gauging stations (Osucheon, Mihocheon, Maruek, and Chogang) respectively. The calibration results showed that the coefficient of determination (R²) was 0.76 in average (0.66 to 0.84) and the Nash-Sutcliffe model efficiency was 0.62 in average (0.52 to 0.72). Based on the 2010s (2006~2015) weather condition for the whole period, the streamflow impact was estimated by applying GIS data for each decade (1980s: 1976~1985, 1990s: 1986~1995, 2000s: 1996~2005, 2010s: 2006~2015). The results showed that the 2010s averaged-wet streamflow (Q95) showed decrease of 4.1~6.3%, the 2010s averaged-normal streamflow (Q185) showed decreased of 6.7~9.1% and the 2010s averaged-drought streamflow (Q355) showed decrease of 8.4~10.4% compared to 1980s streamflows respectively on the whole. During 1975~2015, the increase of groundwater use covered 40.5% contribution and the next was forest growth with 29.0% contribution among the 5 influencing factors.