• Proceedings of the KIEE Conference
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• 1998.11a
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• pp.186-188
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• 1998

This paper describe the dynamic equation of Linear Pulse Motor(LPM)and the method of microstep drive and newly proposed control method for Linear Pulse Motor(LPM). A microstep drive is generally used for the high resolution positioning system. But high thrust distortion and imbalance in LPM make torque ripple that cause position error in microstep drive. In this paper the new control method is proposed and applied to hybrid LPM which is made by KERI. In the experimental results. it is shown the validity of the proposed control scheme.

• Korean Journal of Applied Biomechanics
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• v.21 no.3
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• pp.309-315
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• 2011

The purpose of this study was to evaluate the effect of asymmetric muscle force in lower extremity on dynamic balance during walking. Sixteen elementary students(age: 12.3${\pm}$0.7 yrs, height: 149.4${\pm}$9.7 cm, weight 40.6${\pm}$7.8 kg) who have no musculoskeletal disorder were recruited as the subjects. Temporal parameters, M-L inclination angle of XCoM-CoP, M-L and A-P CoP, loading rate, and decay rate were determined for each trial. For each dependent variable, a independent-sample t-test was performed to test if significant difference existed between each conditions(p<.05). The displacement of antero-posterior COP during RTO-LHC1 in SG was siginificantly smaller than corresponding value in AG. In contrast, the displacement of medio-lateral COP during RTO-LHC1 in SG was greater than those of AG. It seems that imbalance of muscle force may result in increasing the medio-lateral stance in order to minimize the instability. We found that the asymmetric muscle force in the lower extremity may be a reason for the awkward control of impact force.

• Korean Journal of Acupuncture
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• v.26 no.3
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• pp.27-42
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• 2009

Objectives : The vestibular system detects head movement and serve to regulate and maintain the equilibrium and orientation of the body. It is known that the vestibular imbalance leads to vestibular symptoms such as nausea, vomiting, vertigo and postural disturbance. The objectives of the present study were to examine a modification of the dynamic activities of medial vestibular nucleus (MVN) neurons following electroacupuncture (EA) of GB43 (Hyepgye). Methods : In Sprague-Dawley rats weighing $250{\sim}300g$, dynamic responses induced by sinusoidal whole body rotation about vertical axis at 0.2 Hz were observed in MVN of rats during EA of GB43 (Hyepgye) with 0.2 ms, 40 Hz and $600{\pm}200{\mu}A$. Also, expression of cFos protein was observed 2 hours after EA for 30 mins. Results : In dynamic response of vestibular neuron, the excitatory or inhibitory responses of gain were predominant in the ipsilateral MVN neurons during EA but not predominant in the contralateral MVN. Most neurons showing decreased gain were classified to inhibitory responses of spontaneous firing discharge during EA and ones showing increased gain were classified to excitatory response of spontaneous firing discharge during EA. Also, EA of the left GB43 (Hyepgye) for 30 mins produced the expression of cFos protein in MVN, inferior olive (IO) and solitary tract nuclei (SOL). Spatial expressions of cFos protein were predominant in the contralateral MVN, ipsilateral IO and bilateral SOL. Conclusion : These results suggest that the excitability of MVN neurons was influenced by EA of GB43 (Hyepgye) and EA may be related to the convergence on MVN.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.4
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• pp.341-348
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• 2017

This study examined the effects of the location and direction of the scolioti curve on postural balance in patients with idiopathic scoliosis. Fifteen subjects were divided into three groups: right thoracic curve group, left lumbar curve group, and double curve group. The dynamic trunk motion (angle variation in the lumbar, thoracolumbar, lower thoracic and upper thoracic region) and plantar pressure distribution (maximum force and peak pressure) were assessed using an ultrasound-based motion analysis system and Emed-at platform system. From the results, it was confirmed that patients with idiopathic scoliosis showed postural imbalance with an increased angle and pressure asymmetry according to the location and direction of the scoliotic curve for dynamic trunk motion and plantar pressure distribution. In addition, there were differences in the postural balance pattern between the single curve and double curve groups. Further studies for developing a rehabilitation training device will be conducted to improve the postural control ability and trunk balance as well as treat scoliosis based on the results of this study.

• Korean Journal of Social Welfare Studies
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• v.49 no.2
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• pp.5-38
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• 2018

The purpose of this study is to examine work-life balance by analyzing time schedules of married couple. The 2014 Korea Time Use Survey dataset was used for the analysis. Finally, 6,262 time diaries of 3,131 households were included in the analysis. The study used sequence analysis in particular, by applying the Lesnard(2014)'s dynamic hamming matching (DHM) method, which is useful for the time diary analysis where timing is a key factor. This study explored daily schedules of each man and woman according to 9 types of couple-combined work-schedules, which had been already derived by cluster analysis. The daily schedules were identified according to the activities divided as labor, housework, sleep, self-management, active leisure, passive leisure, and others. Here, time allocation was analyzed through various graphs showing average time amount and modal states by time period. Based on the analysis, it summarized that "long working hours as a main factor of work-life imbalance", "gender inequality of time use", "non-standard hours work impairing quality of life and "poverty of leisure time"as characteristics of work-life imbalance. Finally this study discussed the social policy implications to support work-life balance.

• Journal of IKEEE
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• v.28 no.3
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• pp.458-464
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• 2024

This study proposes a fault-tolerant caching system to address the issue of caching content imbalance caused by the dynamic departure and participation of cache servers in a heterogeneous cache server network, and validates it in both real and virtual environments. With the increase of large-scale media content requiring various types and resolutions, the necessity of cache servers as key components to reduce response time to user requests and alleviate network load has been growing. In particular, research on heterogeneous cache server networks utilizing edge computing and low-power devices has been actively conducted recently. However, in such environments, the irregular departure and participation of cache servers can occur frequently, leading to content imbalance among the cache servers deployed in the network, which can degrade the performance of the cache server network. The fault-tolerant caching algorithm proposed in this study ensures stable service quality by maintaining balance among media contents even when cache servers depart. Experimental results confirmed that the proposed algorithm effectively maintains content distribution despite the departure of cache servers. Additionally, we built a network composed of seven heterogeneous cache servers to verify the practicality of the proposed caching system and demonstrated its performance and scalability through a large-scale cache server network in a virtual environment.

• Journal of Korean Tunnelling and Underground Space Association
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• v.25 no.1
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• pp.27-41
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• 2023

Submerged floating tunnels must be connected to the ground to connect continents. The displacement imbalance at the shore connection between the underground bored tunnel and submerged floating tunnel can cause stress concentration, accompanying a fracture at the shore connection. The elastic joint has been proposed as a method to relive the stress concentration, however, the effect of the elastic joints on the dynamic behavior should be evaluated. In this study, the submerged floating tunnel and shore connection under dynamic load conditions were simulated through numerical analysis using a numerical model verified through a small-scaled physical model test. The resonant frequency was considered as a dynamic behavioral characteristic of the tunnel under the impact load, and it was confirmed that the stiffness of the elastic joint and the resonant frequency exhibit a power function relationship. When the shore connection is designed with a soft joint, the resonant frequency of the tunnel is reduced, which not only increases the risk of resonance in the marine environment where a dynamic load of low frequency is applied, but also greatly increases the maximum velocity of tunnel when resonance occurs.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.39 no.2
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• pp.28-36
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• 2016

Recently, owing to the development of ICT industry and wide spread of smart phone, the number of people who use car sharing service are increased rapidly. Currently two-way car sharing system with same rental and return locations are mainly operated since this system can be easily implemented and maintained. Currently the demand of one-way car sharing service has increase explosively. But this system have several obstacle in operation, especially, vehicle stock imbalance issues which invoke vehicle relocation. Hence in this study, we present an optimization approach to depot location and relocation policy in one-way car sharing systems. At first, we modelled as mixed-integer programming models whose objective is to maximize the profits of a car sharing organization considering all the revenues and costs involved and several constraints of relocation policy. And to solve this problem efficiently, we proposed a new method based on particle swarm optimization, which is one of powerful meta-heuristic method. The practical usefulness of the approach is illustrated with a case study involving satellite cities in Seoul Metrolitan Area including several candidate area where this kind systems have not been installed yet and already operating area. Our proposed approach produced plausible solutions with rapid computational time and a little deviation from optimal solution obtained by CPLEX Optimizer. Also we can find that particle swarm optimization method can be used as efficient method with various constraints. Hence based on this results, we can grasp a clear insight into the impact of depot location and relocation policy schemes on the profitability of such systems.

• Proceedings of the Korean Environmental Sciences Society Conference
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• 2003.11a
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• pp.73-78
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• 2003

In this research, we implement Realtime Air Diffusion Prediction System which is a parallel Fortran model running on distributed-memory parallel computers. The system is designed for air diffusion simulations with four-dimensional data assimilation. For regional air quality forecasting a series of dynamic downscaling technique is adopted using the NCAR/Penn. State MM5 model which is an atmospheric model. The realtime initial data have been provided daily from the KMA (Korean Meteorological Administration) global spectral model output. It takes huge resources of computation to get 24 hour air quality forecast with this four step dynamic downscaling (27km, 9km, 3km, and lkm). Parallel implementation of the realtime system is imperative to achieve increased throughput since the realtime system have to be performed which correct timing behavior and the sequential code requires a large amount of CPU time for typical simulations. The parallel system uses MPI (Message Passing Interface), a standard library to support high-level routines for message passing. We validate the parallel model by comparing it with the sequential model. For realtime running, we implement a cluster computer which is a distributed-memory parallel computer that links high-performance PCs with high-speed interconnection networks. We use 32 2-CPU nodes and a Myrinet network for the cluster. Since cluster computers more cost effective than conventional distributed parallel computers, we can build a dedicated realtime computer. The system also includes web based Gill (Graphic User Interface) for convenient system management and performance monitoring so that end-users can restart the system easily when the system faults. Performance of the parallel model is analyzed by comparing its execution time with the sequential model, and by calculating communication overhead and load imbalance, which are common problems in parallel processing. Performance analysis is carried out on our cluster which has 32 2-CPU nodes.

• Korean Journal of Acupuncture
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• v.25 no.3
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• pp.117-135
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• 2008

Objectives: It is known that the vestibular imbalance leads to vestibular symptoms such as nausea, vomiting, vertigo and postural disturbance. Since the non-labyrinthine inputs from the limbs and viscera converge on the vestibular nucleus neurons receiving signal from peripheral vestibular endorgan, acupuncture to the periphery may influence the activities of vestibular nuclear neurons and produce a therapeutic effect on the vestibulacr symptoms. The present study was to examine a modification and characteristics of the static and dynamic activities of medial vestibular nucleus (MVN) neurons following electroacupuncture (EA) of GB43' acupoint. Methods: In 54 Sprague-Dawley adult male rats weighing 250${\sim}$300g, spontaneous firing discharges and dynamic responses induced by sinusoidal whole body rotation about vertical axis at 0.2 Hz were observed in MVN of rats during EA of GB43' acupoint, located between the left 4th and 5th toe, which is the territory of sural and peroneal nerves, with 0.2 ms, 40 Hz and 600${\pm}$200 ${\mu}A$. Results: EA of the left GB43' acupoint induced modifications of spontaneous firing rates in 45% of MVN neurons recorded, and the percentage of modified neurons was 44% in type I, 52% in type II and 46% in non-type neurons. The excitatory or inhibitory responses of spontaneous firing discharges were predominant in the ipsilateral MVN neurons during EA. The excitatory response was abolished after EA but the inhibitory response was prolonged after EA in the ipsilateral MVN. The neurons of MVN showing modified spontaneous firing discharges by EA showed lower frequency (${\geq}$10 spikes/sec) of mean spontaneous firing rates than non affected ones. Conclusion: These results suggest that the neuronal activities of MVN neurons were influenced by EA of GB43' acupoint and the effects of EA may be related to the convergence of the peripheral vestibular inputs and ascending somatosensory inputs on MVN.