• Journal of Ocean Engineering and Technology
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• v.33 no.2
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• pp.99-105
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• 2019

Unlike typical a dynamic positioning (DP) system, a DP-assisted mooring system must determine a set point (SP) that can ensure a mooring tension safety range to prevent an excessive increase in mooring tension. In this paper, a new algorithm for determining the SP is suggested in order to reduce the tension on all the mooring lines. To determine the SP, a working area around the vessel is represented by a rectangular grid. Thus, the size of the grid area is limited considering the offset of a vessel with a mooring system. At each grid's nodes, the resultant tension from all the mooring lines is estimated using the time history of the tension and vessel's position. The results of static analyses for each grid position are used to estimate the global tension. Consequently, the SP is automatically selected as a position satisfying criterion for minimizing the total tension. In order to validate the suggested algorithm, a motion simulation with the control system in the time domain and a discussion of the results are presented.

• Journal of Korean Medicine Rehabilitation
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• v.32 no.1
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• pp.125-131
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• 2022

This study was to investigate the effectiveness of combined Korean medicine treatment on a patient who was diagnosed on lumbosacral transitional vertebra (LSTV) with localized bone marrow edema. The patient was treated with acupuncture, pharmacopucture, cupping and herbal medicine. We evaluated patient's progress using range of motion (ROM), EuroQol-5 dimensions (EQ-5D), Oswestry disability index (ODI), numerical rating scale (NRS), patient global impression of change, self-walkable distance. NRS of back pain decreased from 7 to 5, at the same time NRS of lower limb decreased from 4 to 3. EQ-5D score increased from 0.24 to 0.646. ODI score improved 80 to 62. Self-walkable distance and lumbar spine ROM also increased. As a result, clinical improvements were found in a patient. In conclusion, this study shows that Korean medicine treatment can be considered as effective conservative care for LSTV with localized bone marrow edema.

• Journal of Ocean Engineering and Technology
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• v.36 no.5
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• pp.340-352
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• 2022

This article presents a modeling method for the uncorrelated measurement error of the ultra-short baseline (USBL) acoustic positioning system for aiding navigation of underwater vehicles. The Mahalanobis distance (MD) and principal component analysis are applied to decorrelate the errors of USBL measurements, which are correlated in the x- and y-directions and vary according to the relative direction and distance between a reference station and the underwater vehicles. The proposed method can decouple the radial-direction error and angular direction error from each USBL measurement, where the former and latter are independent and dependent, respectively, of the distance between the reference station and the vehicle. With the decorrelation of the USBL errors along the trajectory of the vehicles in every time step, the proposed method can reduce the threshold of the outlier decision level. To demonstrate the effectiveness of the proposed method, simulation studies were performed with motion data obtained from a field experiment involving an autonomous underwater vehicle and USBL signals generated numerically by matching the specifications of a specific USBL with the data of a global positioning system. The simulations indicated that the navigation system is more robust in rejecting outliers of the USBL measurements than conventional ones. In addition, it was shown that the erroneous estimation of the navigation system after a long USBL blackout can converge to the true states using the MD of the USBL measurements. The navigation systems using the uncorrelated error model of the USBL, therefore, can effectively eliminate USBL outliers without loss of uncontaminated signals.

• Journal of the Korean earth science society
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• v.43 no.4
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• pp.511-519
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• 2022

Given the significant social and economic impact caused by heat waves, there is a pressing need to predict them with high accuracy and reliability. In this study, we analyzed the real-time forecast data from six models constituting the Subseasonal-to-Seasonal (S2S) prediction project, to elucidate the key mechanisms contributing to the prediction of the recent record-breaking Korean heat wave event in 2018. Weekly anomalies were first obtained by subtracting the 2017-2020 mean values for both S2S model simulations and observations. By comparing four Korean heat-wave-related indices from S2S models to the observed data, we aimed to identify key climate processes affecting prediction accuracy. The results showed that superior performance at predicting the 2018 Korean heat wave was achieved when the model showed better prediction performance for the anomalous anticyclonic activity in the upper troposphere of Eastern Europe and the cyclonic circulation over the Western North Pacific (WNP) region compared to the observed data. Furthermore, the development of upper-tropospheric anticyclones in Eastern Europe was closely related to global warming and the occurrence of La Niña events. The anomalous cyclonic flow in the WNP region coincided with enhancements in Madden-Julian oscillation phases 4-6. Our results indicate that, for the accurate prediction of heat waves, such as the 2018 Korean heat wave, it is imperative for the S2S models to realistically reproduce the variabilities over the Eastern Europe and WNP regions.

• Journal of Astronomy and Space Sciences
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• v.40 no.3
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• pp.101-111
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• 2023

We conducted a statistical study of polar mesospheric summer echoes (PMSEs) in relation to magnetic local time (MLT), considering the geomagnetic conditions using the K-index (or K). Additionally, we performed a case study to examine the velocity profile, specifically for high velocities (≥ ~100 m/s) varying with high temporal resolution at high K-index values. This study utilized the PMSE data obtained from the mesosphere-stratosphere-troposphere radar located in Esrange, Sweden (63.7°N, 21°E). The change in K-index in terms of MLT was high (K ≥ 4) from 23 to 04 MLT, estimated for the time PMSE was present. During the near-midnight period (0-4 MLT), both PMSE occurrence and signal-to-noise ratio (SNR) displayed an asymmetric structure with upper curves for K ≥ 3 and lower curves for K < 3. Furthermore, the occurrence of high velocities peaked at 3-4 MLT for K ≥ 3. From case studies focusing on the 0-3 MLT period, we observed persistent eastward-biased high velocities (≥ 200 m/s) prevailing for ~18 min. These high velocities were accompanied with the systematic motion of profiles at 85-88 km, including large shear formation. Importantly, the rapid variations observed in velocity could not be attributed to neutral wind effects. The present findings suggest a strong substorm influence on PMSE, especially in the midnight and early dawn sectors. The large zonal drift observed in PMSE were potentially energized by local electromagnetic fields or the global convection field induced by the electron precipitation during substorms.

• KIPS Transactions on Software and Data Engineering
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• v.13 no.1
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• pp.17-27
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• 2024

Video frame interpolation is an important technique used in the field of video and media, as it increases the continuity of motion and enables smooth playback of videos. In the study of video frame interpolation using deep learning, Kernel Based Method captures local changes well, but has limitations in handling global changes. In this paper, we propose a new U-Net structure that applies feature map differentiation and two directions to focus on capturing major changes to generate intermediate frames more accurately while reducing the number of parameters. Experimental results show that the proposed structure outperforms the existing model by up to 0.3 in PSNR with about 61% fewer parameters on common datasets such as Vimeo, Middle-burry, and a new YouTube dataset. Code is available at https://github.com/Go-MinSeong/SF-AdaCoF.

• Journal of Acupuncture Research
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• v.41 no.2
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• pp.107-114
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• 2024

Background: Low back pain (LBP) is a common musculoskeletal disorder worldwide, with a lifetime prevalence of up to 80%. Among nonsurgical treatments for chronic LBP, Korean medicine treatments are highly preferred, and pharmacopuncture therapy combining acupuncture and herbal medicine is widely used. However, no evidence-based study has focused on the use of various types of pharmacopuncture. Methods: The pragmatic randomized controlled clinical trial will include 44 participants; recruitment will start in July 2023. All participants will receive integrated Korean medicine treatment including acupuncture, cupping, and infrared therapy, and the intervention group will also receive pharmacopuncture. After 16 treatment sessions, twice a week for 8 weeks, follow-up assessments will be performed at week 9. As a pragmatic randomized controlled clinical protocol, the type, dose, and acupoints of acupuncture and pharmacopuncture are not determined in advance but are selected and recorded according to the clinical judgment of the Korean medicine doctor. Results: The primary outcome will be measured using a visual analog scale score, and the secondary outcomes include the Oswestry disability index, patient global impression of change, no worse than mild pain, and range of motion. Safety will be assessed by examining participants' self-reported adverse events and vital signs and conducting blood tests before and after the test. Conclusion: This study aims to provide clinical evidence of the effectiveness and safety of pharmacopuncture for chronic LBP.

• Therapeutic Science for Rehabilitation
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• v.13 no.3
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• pp.51-67
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• 2024

Objective : This study investigated trends in the use of assessment tools by occupational therapists working with adults and older adults. Methods : Occupational therapists were surveyed to gather data on general characteristics, assessment tool usage, assessment time and frequency, usage trends by area, and education. The tools were categorized by the Occupational Therapy Practice Framework (OTPF) into Activities of Daily Living (ADL), Instrumental Activities of Daily Living (IADL), and play and leisure for occupations, and cognitive functions, motor functions, and psychosocial aspects for client factors. Data from 98 respondents were analyzed using frequency analysis and one-way ANOVA with SAS. Results : Most surveyed occupational therapists worked in university or general hospitals (40.82%). The assessment time per patient was under 30 min (62.25%), and re-assessment frequency was one~three months (68.38%). The most frequently used assessment tools by the OTPF were as follows: ADL: Modified Barthel Index (94.90%), IADL: Canadian Occupational Performance Measure (31.63%), cognitive functions: Mini-Mental Status Examination (89.80%), visual perception: Motor-free Visual Perception Test (56.12%), dementia: Global Deterioration Scale (63.27%), motor functions: Jamar Dynamometer & Pinch Gauge (59.18%), dysphagia: Video Fluoroscopic Swallowing Study (28.57%), physical examination: Range of Motion (59.18%), and psychosocial: Geriatric Depression Scale (33.67%). Conclusion : This study identified the use and rationale of assessment tools for occupational therapy in adults and older adults. These findings aim to enhance the curriculum and continuing education of occupational therapists.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.8C
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• pp.1113-1124
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• 2004

In this paper, we proposed a hardware(H/W) structure which can compress and recontruct the input image in real time operation and implemented it into a FPGA platform using VHDL(VHSIC Hardware Description Language). All the image processing element to process both compression and reconstruction in a FPGA were considered each of them was mapped into H/W with the efficient structure for FPGA. We used the DWT(discrete wavelet transform) which transforms the data from spatial domain to the frequency domain, because use considered the motion JPEG2000 as the application. The implemented H/W is separated to both the data path part and the control part. The data path part consisted of the image processing blocks and the data processing blocks. The image processing blocks consisted of the DWT Kernel fur the filtering by DWT, Quantizer/Huffman Encoder, Inverse Adder/Buffer for adding the low frequency coefficient to the high frequency one in the inverse DWT operation, and Huffman Decoder. Also there existed the interface blocks for communicating with the external application environments and the timing blocks for buffering between the internal blocks The global operations of the designed H/W are the image compression and the reconstruction, and it is operated by the unit of a field synchronized with the A/D converter. The implemented H/W used the 69%(16980) LAB(Logic Array Block) and 9%(28352) ESB(Embedded System Block) in the APEX20KC EP20K600CB652-7 FPGA chip of ALTERA, and stably operated in the 70MHz clock frequency. So we verified the real time operation of 60 fields/sec(30 frames/sec).

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.25 no.3
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• pp.128-137
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• 2013

Due to the global warming and air pollution, interest in renewable energies has increased in recent years. In particular, the crisis of the depletion of fossil energy resources in the near future has accelerated the renewable energy technologies. Among the renewable energy resources, oceans covering almost three-fourths of earth's surface have an enormous amount of energy. For this reason, various approaches have been made to harness the tremendous energy potential. In order to achieve two purposes: to improve harbor water quality and to use wave energy, this study proposed a sea water exchange structure applying an Oscillating Water Column (OWC) wave generation system that utilizes the air flow velocity induced by the vertical motion of water column in the air chamber as a driving force of turbine. In particular, the airflow velocity in the air chamber was estimated from the time variations of water surface profile computed by using 3D-NIT model based on the 3-dimensional irregular numerical wave tank. The relationship of the frequency spectrums between the computed airflow velocities and the incident waves was analyzed. This study also discussed the characteristics of frequency spectrums in the air chamber according to the presence of the structure, wave deformations by the structure, and the power of the water and air flows were also investigated. It is found that the phase difference exists in the time series data of water level fluctuations and air flow in the air chamber and the air flow power is superior to the fluid flow power.