• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.10B
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• pp.927-937
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• 2003

Network based VPN(Virtual Private Network) using MPLS(Multiprotocol Label Switching) technology is regarded as a good solution for intranets or extranets because of the low cost and the flexibility of the service provision. In this paper, we describea mechanism that allows the VPN users to move from one site to another site of the VPN network based on the BGP-E MPLS technology. This mechanism is designed for and implemented on PE(Provider Edge) routers of the backbone network. PE routers connected to the VPN sites establish a new MPLS path to the mobile node after they detect movement of the mobile VPN node. The new location may belong to the same VPN or to different VPN. We designed VPN management and control functions of the PE routers in order to interface with the Mobile IP protocol. The pilot implementation and performance measurement were carried out on a testbed.

• Korean Journal of Applied Biomechanics
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• v.24 no.4
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• pp.425-433
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• 2014

The purpose of the study was to investigate the effect of CAD (Computer Aided Design) based alpine mono-ski bucket design on disabled ski athletes' kinematic characteristics. Two national team ski athletes with LW11 disabilities (Locomotion Winter Classification) category for sit ski participated in both pre and post experiment. Both of the subjects performed 3 trials of carved turn on a ski slope under two conditions. Where, subject "A" performed pre experiment with personal bucket and post experiment with the newly developed CAD based bucket whereas, Subject "B" as control subject performed both pre and post experiment with his personal bucket. For the experiment, 24 Infrared cameras were positioned on the ski slope which covered the path of the ski turn. Also, motion capture suit with reflective markers were worn by both subjects. In the result, decrement in medial/lateral displacement of COM, anterior/posterior displacement of COM, flexion/extension angle of trunk as well as velocity losing rate of COM was observed in subject "A" when using the newly developed CAD based bucket. In contrast, no larger effect on performance was observed when using personal buckets. In conclusion, the findings obtained from the study indicated effectiveness of newly developed CAD based bucket by reducing excessive movement of hip and trunk which is an important factor to perform an effective turn.

• Journal of the Institute of Electronics and Information Engineers
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• v.52 no.7
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• pp.153-161
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• 2015

In the present study, as part of the technology development (Quality of Life Technology, QoLT) to improve the socio-economic status of people with disabilities as an extension of these studies, we propose the development of the smart wheelchair system and navigation technology for stable and safe driving in various environments. For the disabled and the elderly make driving easy and convenient with manual/autonomous driving condition, we firstly develop the user-oriented smart wheelchair system with optimized sensors for environment recognition, and then we propose a navigation framework of a hierarchical structure to ensure real-time response, as well as driving stability when traveling to various environmental changes, and to enable a more efficient operation. From the result of several independent experiments, we ensure efficiency and safety of smart wheelchair and its navigation system.

• Journal of The Korean Society of Integrative Medicine
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• v.9 no.1
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• pp.101-108
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• 2021

Purpose : The purpose of this study is to verify the effect of selective muscle strengthening of the knee joint extensor muscles using a pressure biofeedback unit to improve knee extensor strength and the balance ability of total knee replacement patients. Through this, we tried to provide clinical information. Methods : In this study, 12 patients with total knee replacement were recruited from a rehabilitation hospital. They were divided into two groups: a feedback group (n=6) and a control group (n=6). All patients received 30 minutes of continuous passive motion and leg-strengthening exercises for 15 minutes five times a week for two weeks. Subjects performed knee extension exercises with or without biofeedback units in the sitting position. The knee extensor strength and balance ability were measured before and after exercise. Knee extensor strength was measured by Biodex system 3 and balance ability was measured by Balancia software. Results : Both the experimental group and the control group showed a significant difference in the muscle strength of the knee joint extensor muscles after intervention (p<.05). In comparison, the experimental group showed a significant difference than the control group (p<.05). Both the experimental group and the control group showed a significant difference in the velocity average, path length, area 95 % center of pressure (COP), weight distribution, five times sit to stand test (FTSST) after intervention. In comparison, the experimental group showed a significant difference in velocity average, area 95 % COP, and FTSST than the control group (p<.05). Conclusion : In order to strengthen the knee extensor muscle and improve the balance ability in total knee replacement patients, it is necessary to consider providing pressure biofeedback unit during leg strengthening exercises.

• Korea Trade Review
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• v.46 no.2
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• pp.55-74
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• 2021

Despite the growing importance of the logistics industry, it has been socially recognized as a 3D job and is perceived as a field of lower professional identity since the workers themselves think that they are engaged in a less important job. According to the related researches, it shows that professional identity affects the quality of service to customers, and applying it to the workers who are engaged in the logistics industry should be a meaningful subject of research. Therefore, this study intends to look into the impact of professional identity by managers in logistics centers on their service orientation and job engagement. To this end, this study surveyed managers in logistics centers across the country and conducted exploratory factor analysis, confirmatory factor analysis, and path analysis through structural equation models. The results of this study are summarized as follows. First, among the sub-factors of professional identity, recognition of professionalism did not have a significant effect on service orientation and job engagement, while acquisition recognition and range cognition had significant effects on it. Second, service orientation had a significant effect on job engagement. It believes that this study suggested implications for educational institutions and logistics companies that develop human resources of logistics in the aspect of that it presented the importance of developing human resources of logistics as well as the directivity to where the working environment such as the autonomy in their works and the extension of their authority should take their way.

• The Journal of the Acoustical Society of Korea
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• v.13 no.6
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• pp.75-82
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• 1994

The ray paths and travel times of sound wave in the ocean depend on the physical properties of the propagating media. Ocean Acoustic Tomography(OAT), which is inversely estimate the travel time variations between fixed sources and receivers the physical properties of the corresponding media can he understood. To apply ocean survey technology by using the OAT, the tomographic procedure requires forward problem that variation of the travel times be identified with the variability of the medium. Also, received signals must be satisfied the necessary conditions of ray path stability, identification and resolution in order for OAT to work. The canonical ocean has been determined based on the historical data and its travel time and ray path are used as reference values. The sound speed of canonical ocean in the East Sea is about 1523 m/s at the surface and 1458 m/s at the sound channel axis(400m). Sound speeds in the East Sea are perturbed by warm eddy whose horizontal extension is more than 100 km with deeper than 200 m in depth scale. In this study, an acoustic source and receiver are placed at the depth above the sound channel axis, 350 m, and are separated by 200 km range. Ray paths are identified by the ray theory methed in a range dependent medium whose sound speeds are functions of a range and depth. The eigenray information obtained from interpolation between the rays bracketing the receiver are used to simulate the received signal by convolution of source signal with the eigenray informations. The source signal is taken as a 400 Hz rectangular pulse signal, bandwidth is 16 Hz and pulse length is 64 ms. According to the analysis of the received signal and identified ray path by using numerical model of underwater sound propagation, simulated signals satisfy the necessary conditions of OAT, applied in the East Sea.

• Journal of the Korean Association of Geographic Information Studies
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• v.20 no.3
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• pp.67-79
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• 2017

Increasing transportation dependence on the metro system has lead to the convenience of passengers becoming as important as the transportation capacity. In this study, a pedestrian simulator has been developed that can quantitatively assess the pedestrian environment in terms of attributes such as speed and distance. The simulator consists of modules designed for 3D indoor map authoring and algorithmic pedestrian modeling. Module functions for 3D indoor map authoring include 3D spatial modeling, network generation, and evaluation of obtained results. The pedestrian modeling algorithm executes functions such as conducting a path search, allocation of users, and evaluation of level of service (LOS). The primary objective behind developing the said functions is to apply and analyze various scenarios repeatedly, such as before and after the improvement of the pedestrian environment, and to integrate the spatial information database with the dynamic information database. Furthermore, to demonstrate the practical applicability of the proposed simulator in the future, a test-bed was constructed for a currently operational metro station and the quantitative index of the proposed improvement effect was calculated by analyzing the walking speed of pedestrians before and after the improvement of the passage. The possibility of database extension for further analysis has also been discussed in this study.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.17 no.2 s.105
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• pp.139-147
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• 2006

This paper suggests an efficient method of protection ratio calculation and shows some results applicable to frequency coordination in microwave(M/W) relay system networks, and the net filter discrimination(NFD) associated with Tx spectrum mask and overall Rx filter characteristics has been examined to obtain the adjacent channel protection ratio. The protection ratio comprises several factors such as C/N of modulation scheme, noise-to-interference ratio, multiple interference allowance, fade margins of multi-path and rain attenuation, and NFD. According to computed results for 6.7 GHz, 64-QAM, and 60 km at BER $10^{-6}$, fade margin and co-channel protection ratio are 41.1 and 75.2 dB, respectively. NFD for channel bandwidth of 40 MHz reveals 28.9 dB at the first adjacent channel, which results in adjacent channel protection ratio of 46.3 dB. In addition, NFD and protection ratio for different systems with channel bandwidth 20 and 40 MHz have been investigated to be used for actual M/W networks. The proposed method provides some merits of an easy calculation, systematic extension, and applying the same concept to frequency coordination in millimeter wave relay system networks.

• Journal of Korea Multimedia Society
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• v.14 no.1
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• pp.33-43
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• 2011

Routing technologies considering QoS-based hypermedia services have been seen as a crucial network property in next generation optical Internet (NGOI) networks based on IP/dense-wavelength division multiplexing (DWDM). The huge potential capacity of one single fiber. which is in Tb/s range, can be exploited by applying DWDM technology which transfers multiple data streams (classified and aggregated IP traffics) on multiple wavelengths (classified with QoS-based) simultaneously. So, DWDM-based optical networks have been a favorable approach for the next generation optical backbone networks. Finding a qualified path meeting the multiple constraints is a multi-constraint optimization problem, which has been proven to be NP-complete and cannot be solved by a simple algorithm. The majority of previous works in DWDM networks has viewed heuristic QoS routing algorithms (as an extension of the current Internet routing paradigm) which are very complex and cause the operational and implementation overheads. This aspect will be more pronounced when the network is unstable or when the size of network is large. In this paper, we propose a flooding-based unicast and multicast QoS routing methodologies(YS-QUR and YS-QMR) which incur much lower message overhead yet yields a good connection establishment success rate. The simulation results demonstrate that the YS-QUR and YS-QMR algorithms are superior to the previous routing algorithms.

• Journal of Korean Neurosurgical Society
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• v.29 no.7
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• pp.935-939
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• 2000

Objective : Traumatic disc lesion is a lesion with tremendous controversies. The causal relationships of this lesion are not established along with pathogenesis, diagnostic criteria, methods of treatment and the outcome. However, a significant number of patients with back pain after a trauma underwent spinal operations under the diagnosis of traumatic disc lesions. Such an ill-directed operation eventually produce a person with an iatrogenic disability. We present two illustrative cases, and tried to make a preventive method. Methods : We examined the path from mild trauma after a road traffic accident into the iatrogenic disability in two illustrative cases, who requested disability assessment and medical appraisement. We evaluated the reason and background for such an unwanted outcome and tried to find a method to reduce or prevent it by a literature review. Results : These two patients were admitted to the hospital with the diagnosis of lumbar sprain after a road traffic accidents. They eventually underwent spinal surgery under another diagnosis such as traumatic disc herniation or internal disc disruption. They stayed at the hospital for more than six months and finally lost their jobs. They became the disabled at last. Although they complained back pain, they never insisted by themselves that their symptoms were due to the traumatic disc lesion. To prevent such an iatrogenic disability, the doctors should assist them to go-back to the workplace promptly instead of a reckless extension of the treatment period. It may be necessary to evaluate the certificates to extend the treatment period with an additional diagnosis by a medical expert. To reduce the unnecessary long-term admission, a new billing system such as a partial share for the high cost of the treatment by the patients may be needed. Conclusion : It is not the patient but the doctors, who has the responsibility to avoid the unnecessary operations. All treating doctors should try to reduce or prevent such an iatrogenic complication caused by ourselves before we are forced to do so.