• KSII Transactions on Internet and Information Systems (TIIS)
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• v.15 no.12
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• pp.4584-4599
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• 2021

In IEEE 802.11p-based wireless access in vehicular environments (WAVE) communication systems, channel estimation (CE) is one of the important issues to provide stable communication service. It is hard to apply conventional CE schemes based on data pilot to real systems, because error propagation occurs in high mobility and modulation order environments, resulting in degrading the CE performance. In this paper, we propose one data pilot using multiple receive antennas (ODPM) CE scheme based on the weighted sum using update matrix (WSUM) with time-domain averaging (TDA) to overcome this problem. Within the process of WSUM-TDA in the proposed scheme, the maximum ratio combining (MRC) technique is applied so as to create more accurate one data pilot. Moreover, a new reliability test criterion is proposed as the fashion of utilizing MRC, which makes it possible to apply selective TDA that guarantees performance improvement. In simulation results, the packet error rate (PER) performance of the proposed ODPM is compared with that of conventional CE methods and its superiority is demonstrated.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.15 no.12
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• pp.4364-4384
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• 2021

The dynamic network state and the mobility of the terminals make the service function chain (SFC) orchestration mechanisms based on static and deterministic assumptions hard to be applied in SDN/NFV mobile edge computing networks. Designing dynamic and online SFC orchestration mechanism can greatly improve the execution efficiency of compute-intensive and resource-hungry applications in mobile edge computing networks. In order to increase the overall profit of service provider and reduce the resource cost, the system running time is divided into a sequence of time slots and a dynamic orchestration scheme based on an improved column generation algorithm is proposed in each slot. Firstly, the SFC dynamic orchestration problem is formulated as an integer linear programming (ILP) model based on layered graph. Then, in order to reduce the computation costs, a column generation model is used to simplify the ILP model. Finally, a two-stage heuristic algorithm based on greedy strategy is proposed. Four metrics are defined and the performance of the proposed algorithm is evaluated based on simulation. The results show that our proposal significantly provides more than 30% reduction of run time and about 12% improvement in service deployment success ratio compared to the Viterbi algorithm based mechanism.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.16 no.8
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• pp.2606-2626
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• 2022

In this paper, a unmanned aerial vehicle (UAV) access deployment algorithm is proposed, which is based on an improved virtual force model to solve the poor coverage quality of UAVs caused by limited number of UAVs and random mobility of users in the deployment process of UAV base station. First, the UAV-adapted Harris Hawks optimization (U-AHHO) algorithm is proposed to maximize the coverage of users in a given hotspot. Then, a virtual force improvement model based on user perception (UP-VFIM) is constructed to sense the mobile trend of mobile users. Finally, a UAV motion algorithm based on multi-virtual force sharing (U-MVFS) is proposed to improve the ability of UAVs to perceive the moving trend of user equipments (UEs). The UAV independently controls its movement and provides follow-up services for mobile UEs in the hotspot by computing the virtual force it receives over a specific period. Simulation results show that compared with the greedy-grid algorithm with different spacing, the average service rate of UEs of the U-AHHO algorithm is increased by 2.6% to 35.3% on average. Compared with the baseline scheme, using UP-VFIM and U-MVFS algorithms at the same time increases the average of 34.5% to 67.9% and 9.82% to 43.62% under different UE numbers and moving speeds, respectively.

• Elastomers and Composites
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• v.57 no.4
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• pp.197-204
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• 2022

Recently, the demand has increased for protective clothing materials capable of shielding the wearer from bullets, fragment bullets, knives, and swords. It is therefore necessary to develop light and soft protective clothing materials with excellent wearability and mobility. To this end, research is being conducted on hybrid design methods for various highly functional materials, such as carbon nanotube (CNT) sheets, which are well known for their low weight and excellent strength. In this study, a hybrid protective material using CNT sheets was developed and its performance was evaluated. The material design incorporated a bonding method that used a binder for interlayer combination between the CNT sheets. Four types of binders were selected according to their characteristics and impregnated within CNT sheets, followed by further combination with aramid fabric to produce the hybrid protective material. After applying the binder, the tensile strength increased significantly, especially with the phenoxy binder, which has rigid characteristics. However, as the molecular weight of the phenoxy binder increased, the adhesive force and strength decreased. On the other hand, when a 25% lightweight-design and high-molecular-weight phenoxy binder were applied, the backface signature (BFS) decreased by 6.2 mm. When the CNT sheet was placed in the middle of the aramid fabric, the BFS was the lowest. In a stab resistance test, the penetration depth was the largest when the CNT sheet was in the middle layer. As the binder was applied, the stab resistance improvement against the P1 blade was most effective.

• Journal of Fashion Business
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• v.27 no.3
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• pp.96-114
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• 2023

In modern society, there is a tendency to prioritize both fashion and comfort, with a preference for loose-fit clothing that enhances mobility. While darts may not be visibly present on the garment's exterior, their effects should be dispersed and incorporated into the design. However, there is a significant lack of systematic research on dartless patterns in the current state. Therefore, this study focuses on investigating dartless patterns used in loose-fit clothing tailored to the body measurements of women in their 20s. The objective of this research is to develop foundational dartless patterns that serve as a basis for diverse design possibilities in loose-fit clothing. To achieve this purpose, seven dartless patterns introduced in clothing construction references were selected for the production of experimental prototypes, which were then subjected to visual evaluations by a panel of experts. Based on the evaluation results, superior patterns were selected and they underwent modification and improvement to develop the research patterns. The developed research patterns were derived through the formulation of calculation formulas, and based on these formulas, garments were produced. Subsequently, a second round of visual evaluations was conducted by a panel of experts, and notable improvements were observed in most of the aspects assessed. However, it should be noted that this study was limited to women in their 20s it did not explore a wide range of fabrics. Therefore, further research is needed in the future.

• Journal of the Society of Naval Architects of Korea
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• v.61 no.2
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• pp.68-76
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• 2024

The rotor sail is one of the representative devices in eco-friendly wind-assisted propulsion systems that have been practically applied to commercial ships. The present study proposes an asymmetric vertical folding rotor sail (AFRS) designed for small ships, featuring asymmetric geometry along the vertical direction and the function of vertical folding. To evaluate the aerodynamic performance of rotor sail, the drag, lift and lift-to-drag ratio were derived using computational fluid dynamics. The aerodynamic performance of AFRS was compared with that of normal rotor sail with different aspect ratios and spin ratios. The effect of geometric parameters on the aerodynamic performance of AFRS was assessed by varying the asymmetric diameter ratio. The maximum improvement in lift-to-drag ratio for AFRS was approximately 12% in the considered case. Additionally, the resistance is decreased when AFRS is vertically folded without rotating. Throughout the present study, improved aerodynamic and resistance performances for AFRS were confirmed, which will successfully provide additional propulsion to small ships.

• The Journal of Internal Korean Medicine
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• v.45 no.1
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• pp.75-86
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• 2024

Spinal cord infarction is one of the rare strokes with no clear signs of serious nerve damage or after-effects. This study reports on the effectiveness of a combined treatment of Korean medicine and acupuncture on bilateral paraplegia, dysuria, and constipation in a patient with sudden-onset spinal cord infarction. An 84-year-old male patient was diagnosed with spinal cord infarction in August 2022. After diagnosis by whole spine MRI, he received treatment for two months at another hospital, but the improvement was insignificant. He then received Korean medicine treatment, and during this period, his lower extremity manual muscle test grade improved from 3 to 4 and his modified Rivermead mobility index score increased by 13 points, compared with hospitalization. Dysuria improved with acupuncture, and constipation improved with herbal medicine treatment. A combination of herbal medicine and acupuncture can be used to treat paraplegia, dysuria, and constipation caused by spinal cord infarction.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.3
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• pp.1212-1219
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• 2012

This study was to investigate the balancing and clinical abilities trunk muscle stabilization exercise and trunk muscle resistive exercise of stroke patients having surface changes in balance of body. The subjects of this study were 30 stroke patients(15 males and 15 females) that three times a week for 12 weeks at the same time point and with the same amount of exercise. They were separated into two groups and did reinforcing exercise on trunk muscle stabilization exercise and trunk muscle resistive exercise for three times a week for twelve weeks. It were measured balancing ability, they performed functional standing balance test, functional forward arm stretching test. performance-oriented mobility assessment, berg balance scale. The balancing exercises were modified from preceding studies and consisted of 6 difference exercises. The functional standing test with open and close eyes and performance-oriented mobility assessment, the trunk muscle stabilization exercise group and the trunk muscle resistive exercise group improved significantly. The forward arm stretching was test the trunk muscle stabilization exercise group more improved. This study found that the balancing exercise on trunk muscle stabilization exercise was more effective than trunk muscle resistive exercise for stroke patients. Thus, trunk muscle stabilization exercise has more positive effects on the improvement of balancing abilities of stroke patients.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.12
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• pp.542-550
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• 2016

This study analyzed the direct and indirect effects of job competency education on job goal setting, job preparation behavior and first job satisfaction from the perspective that successful employment requires improving the job ability needed for college students. Data on 5,044 students were analyzed based on the 2013GOMS of Graduates Occupational Mobility Survey(GOMS). The study findings are summarized as follows. First, job competency education not only acted positively on job goal setting but also contributed to promoting job preparation behavior. Second, job preparation behavior contributed to improving satisfaction with the first job. Third, indirect effects of job competency education and job goal setting in first job satisfaction. In conclusion, job competencies enhances the possibility that college students may obtain their wanted job by setting a clear goal for their job and having a positive effect on the required behavior. Accordingly, college student should try to reinforce their special capability to accomplish the given job as career professionals in consideration of their aptitude rather than devoting themselves to reinforcing their basic capability such as linguistic ability. For this purpose, both universities and the government should develop educational programs for college students to grasp their aptitude and cultivate their special ability to become career professionals and provide a foundation for them to become talented professionals armed with special capability by proving support for job ability improvement.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.16 no.2
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• pp.92-104
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• 2017

Previous management for speed in road traffic system was aimed only to the improvement of mobility and safety. However, consideration for the aspect of environment and energy consumption efficiency was valued less than the former ones. Nevertheless, economical damage scope caused by climate change has been increasing and it is estimated that environmental value will be increased because of the change of external circumstances. In addition, policy for reducing carbon emission in transportation system was assessed as insufficient in improving the condition of traffic road since it only focused on the transition of private vehicle into public transportation and development of eco-friendly car. Now it is the time to prepare for the adaptation strategy and precaution for the increased number of private vehicle in Korea. For this, paradigm shift in traffic operation which includes the policy not only about the mobility but also about caring environment would be needed. It is needed to be able to monitor the actual amount of greenhouse gas in real time to reduce the amount of emitted greenhouse gas in the aspect of traffic management. In this research, a methodology which can build on-line greenhouse gas emission monitoring system by using real time traffic data and predicting the circumstance in next 5 minutes was suggested.