• KEPCO Journal on Electric Power and Energy
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• 제7권2호
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• pp.249-254
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• 2021

As the spreading speed of electric vehicles increases rapidly, those are expected to be able to use them as flexible resources in the power system beyond the concern for the supply of its charging power. Especially when the Renewable Energy sources (RES) which have no intrinsic control capability have replaced the synchronous generators more and more, the power system needs to secure the additional frequency control resources to ensure its stability. However, the feasibility of using electric vehicles as the frequency control resources should be analyzed from the perspective of the power system operation and it requires the existing simulation frameworks for the power system. Therefore, this paper proposes the grid connected modeling of the primary frequency control provided by electric vehicles which can be integrated into the existing power system model. In addition, the proposed model is implemented considering technical performances constrained by the characteristics of the Vehicle-Grid Integration (VGI) system so that the simulation results can be accepted by the power utilities operating the power system conservatively.

• The Journal of Korean Institute of Communications and Information Sciences
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• 제40권11호
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• pp.2305-2315
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• 2015

Frequency resource value is growing more and more with the development of the wireless communication. With the advent of the current information society comes a serious shortage of frequency resource, as the amount of supply is far from meeting its demands. Thus, cognitive radio (CR) technique is receiving more attention as a way to make use of the temporarily unoccupied frequency resource. In this paper we propose a novel out-of-band spectrum sensing and dynamic channel access scheme for frequency hopping-based cognitive radio ad-hoc networks. At the beginning of each current channel hopping time, member nodes perform spectrum sensing for the next hopping channel. Based on the proposed collision free primary detection notification, member nodes can determine whether they should execute a hopping time extension procedure of the current channel or not. When the primary detected hopping channel is re-idled, the hopping pattern recovery procedure is performed. In this paper we evaluated the performance of the proposed dynamic sensing and hopping channel extension mechanism for the various wireless network conditions. As a result, we show that the proposed method can increase channel utilization and provide reliable channel management operation.

• The Journal of Korean Medicine
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• 제28권3호통권71호
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• pp.289-298
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• 2007

Objectives : Electrical acupoint stimulation (EAS) has been used to treat motor dysfunction of stroke patients with reportedly effective results. The purpose of this study was to evaluate the efficacy of EAS with different frequencies in treating motor dysfunction of ischemic stroke patients. Methods : The subjects of this study were sixty-two ischemic stroke patients with motor dysfunction at Kyunghee Oriental Medicine Hospital who were hospitalized for one week to one month from onset. They were treated with 2Hz or 120Hz EAS for two weeks, and motor evoked potentials (MEP) were measured before and after EAS treatment. To compare the effect of 2Hz EAS with 120Hz, we measured latency, central motor conduction time (CMCT) and amplitude of MEP before and after EAS treatment. Results : After two weeks of treatment, we compared MEP data of the affected side between the 2Hz group and the 120Hz group. The 2Hz group showed more significant improvement than the 120Hz group in latency, CMCT and amplitude (P=0.008, 0.002, 0.002). In case of the affected side MEP data divided by normal side MEP data, the 2Hz group also showed improvement on latency, CMCT and amplitude with significant differences (P=0.003, 0.000, 0.008). Conclusions : These results suggest that low frequency EAS activates the central motor conduction system better than high frequency EAS, and it means that EAS with low frequency is more helpful for motor recovery after ischemic stroke than that with high frequency.

• Journal of Korean Academy of Fundamentals of Nursing
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• 제9권1호
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• pp.86-100
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• 2002

Purpose: The purpose of the study was done to identify the nursing care needs of patients in the recovery room. Method: The subjects in this study were 127 patients in a recovery room between 6/9/2001 and 24/9/2001. The instrument used for this study was the descriptive questionnaire developed by Shin Hyun-Jin (1999). The data was analysed by frequency, percentage, mean, standard deviation, t-test, ANOVA, and factor analysis using the SPSS program. Result: 1) Kaiser - Meyer -O1kin sample appropriateness was 799 and Bartlett's test of sphericity significant probability was .000. 2) The mean score for nursing care need of patients in the recovery room was $4.17{\pm}.51$ of a total possible score of 5. The score of nursing need for different parameters was as follows : Educational need ($4.31{\pm}.49$), physical need ($4.27{\pm}.47$), emotional need ($4.11{\pm}.52$), environmental need ($3.99{\pm}.56$). 3) Differences in the needs for nursing care according to the demographics were significant for gender, marital status, operation experience, and departments consulted. General characteristic variables significantly related to nursing need were as follows: Physical need significantly related to the departments consulted (F=2.23, p=.036). Educational need significantly related to the marital status (F=2.55. p=.012), departments consulted (F=2.30, p= 031). Emotional need significantly related to the marital status (F=2.22, p=.028). Environmental need significantly related to the gender (t=-2.44, p= .016), marital status (F=2.01, p= .046). operation experience (t=-1.99. p= .048). Conclusion: Nursing care needs of patients in the recovery room are significantly related to educational need, physical need, emotional need and environmental need. Intervention plans and program need to be developed to improve strategies to meet nursing needs of patients in the recovery room.

• Transactions of the Korean Society of Mechanical Engineers A
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• 제34권10호
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• pp.1339-1344
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• 2010

MSM (Modal Superposition Method) is a technique for analyzing structural durability by taking the vibration characteristics into consideration. In this paper, MSR (Modal Stress Recovery) method, which is similar to MSM, was reviewed to check its validity as a durability analysis method. The MSR method directly calculates the modal displacement time history in multibody dynamics analysis; as a result, the total analysis time is shorter than that of MSM method. We conduct durability analysis using the MSR method and a durability test of a torsion beam axle that is affected by various road loads within the natural frequency of the beam axle. The analysis results for critical location and durability were in good agreement with the respective test results. Therefore, durability analysis using the MSR method is effective in predicting the durability of the structures of various dynamic systems.

• Journal of Embryo Transfer
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• 제11권3호
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• pp.309-316
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• 1996

The aim of this study is to elucidate sperm chemotaxis and to set up the optirnal condition for selection of motile and capacitated sperm from hovine frozen-semen. Thus, the effects of semen-washing after thawing, concentrations of progesterone (P4) and bovine serum albumin (BSA), and sperm-washing frequency on sperm selection were examined. For evaluating their effects, number, viability and acrosome reaction of sperm swim-up seperated from semen, which were incubated for 30 minutes at 36$^{\circ}C$ in the M2 solution containing P4 and BSA, were investigated. For frozen-semen just after thawing, sperm recovery and viability were not significantly different between P4-treated and -untreated semen. However, washing frozen-semen decreased the number of sperm and increased the viability of sperm that were recovered from semen treated with P4. Progesterone affected the recovery rate, the viability and the acrosome-reaction rate of sperm recovered from washed frozen-semen. Especially, number of motile and capacitated sperm were highest in semen treated with 50$\mu$g /ml among 0, 20, 50 and 100$\mu$g /ml of P4 concentrations. BSA affected the recovery rate and the viability of sperm recovered from washed frozen-semen that were treated with 50$\mu$g /ml of P4. Especially, the percentage of viable sperm were highest in semen treated with 4mg /ml among 0, 2, 4, and 6mg /ml of BSA concentrations. Repeatedly sperm-washing did not affect the recovery rate and the viability of sperm recovered from washed frozen-semen that were treated with 50$\mu$g /ml of P4 and 4mg /ml of BSA In conclusion, using progesterone and BSA could efficiently make the selection of motile and capacitated sperm from washed frozen-semen.

• The Journal of Society for e-Business Studies
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• 제22권4호
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• pp.103-115
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• 2017

Globally, frequency and scale of natural disasters are growing, also the damage is increasing. In view of the damage by natural disasters for several years, it is true that Korea is not free from such damages. In this paper, we propose a process to efficiently manage recovery resources in case of disaster damage. We utilize the IoT technology to detect the resource status in real time, and configure the process so that the state and movement of the recovery resource can be grasped in real time through the resource activity recognition module. In addition, we designed the database that is necessary to actualize it, and developed and experimented resource activity recognition module using smart-phone sensors. This will contribute to building a quick and efficient disaster response system.

• Journal of the Korea Institute of Information and Communication Engineering
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• 제21권5호
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• pp.899-905
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• 2017

This paper presents a reference-less dual loop clock and data recovery (CDR) circuit that supports a data rate of 2.496 Gb/s for the mobile industry processor interface (MIPI) M-PHY. An adaptive loop bandwidth scheme is used to implement the fast lock time maintaining a low time jitter. To this scheme, the proposed CDR consists of two loops for a frequency locked loop and a phase locked loop. The proposed 2.496 Gb/s reference-less dual loop CDR is designed using a 65 nm CMOS process with 1.2 V supply voltage. The simulated peak-to-peak jitter of output clock is 9.26 ps for the input data of 2.496 Gb/s pseudo-random binary sequence (PRBS) 15. The active area and power consumption of the implemented CDR are $470{\times}400{\mu}m^2$ and 6.49 mW, respectively.

• The Journal of Korean Medicine
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• 제23권2호
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• pp.180-189
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• 2002

Background and Purpose : The hemiplegic upper extremity is affected in many stroke patients, and recovery is often poor. The purpose of this study was to assess the efficacy of electroacupuncture (EA) in enhancing the upper extremity motor and functional recovery of ischemic stroke patients. Subjects and Methods : Forty ischemic stroke patients (the upper extremity Fugl-Meyer motor scale (FM) score lower than 46, lesion location within middle cerebral artery territory) within 2 weeks of stroke onset were randomly allocated to either an EA group that received EA treatment or a control group that received only routine ward care. The EA was applied at Quchi-Shousanli (LI11-LI10), Waiguan-Hegu (TE5-LI4) points on the hemiparetic side six times per week for 4 weeks. The frequency of stimulation was 25-50Hz and the intensity was set at a level sufficient to induce muscle contraction. EA treatment was given for 30 minutes and all patients of both groups received standard rehabilitation program. Outcomes were assessed, in a blind manner, before treatment began and at 4 weeks after treatment, with the FM, the Motor Power score (MP) for shoulder/elbow, and the subsection of the Modified Barthel Index (MBI) for drinking/feeding/dressing upper body/grooming. Results : These 2 groups had comparable clinical characteristics, lesion location, lesion size, and pretreatment impairment scores. By the end of treatment, the EA group showed significantly more improvement than the control group in the subsection of the FM for shoulder/elbow/coordination (6.4 vs. 3.7; P=0.047) and the MP for shoulder/elbow (5.3 vs. 3.3; P=0.008). The subsection scores of the MBI for drinking/feeding/dressing upper body/grooming were not significantly different between two groups. No adverse effects due to treatment were found Conclusion : These results suggest that EA enhances the upper extremity motor recovery of acute stroke patients. However, this study failed to demonstrate any significant functional benefit related with upper extremity. Future study should be carried out in a larger sample size and use the functional outcome measure that is more specific and sensitive to the upper extremity.

• Journal of Animal Reproduction and Biotechnology
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• 제34권4호
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• pp.300-304
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• 2019

This study was conducted to examine the oocyte recovery efficiency through having an OPU session once and twice a week. Also, the oocyte recovery efficiency was examined by using OPU after two and three months of rest period. Six cows were used for oocytes collection and were randomly divided into two groups. In experiment 1, OPU sessions were conducted once and twice a week to collect oocytes. The collected oocytes between once and twice OPU groups were classified into four groups (grade 1, 2, 3 and 4) according to the quality of cumulus cells and ooplasm. Based on the result, the percentage of collected oocytes per aspirated follicle number was similar between once and twice OPU session groups (65.5 ± 1.9 and 68.7 ± 1.4 vs.). However, the percentage of grade 1 oocytes from the twice OPU session group was significantly high compared with that of the once a week OPU session group (25.3 ± 0.9 and 32.5 ± 1.2% vs. once and twice session group, respectively, p < 0.05). In experiment 2, the group with three months of rest period tended to have a high percentage of collected oocyte compared with the group with two months of rest period (64.6 and 70.9% vs. 2 and 3 months rest group, respectively, p = 0.62). The percentage of grade 4 in the group with three months of rest period was significantly low compared with the group with two months of rest period group (27.3 and 36.5% vs. two and three months rest group, respectively, p = 0.05). In conclusion, twice a week OPU session is suitable for collection of high quality oocytes by using OPU, and three months of rest period is needed for the recovery of oocyte quality of a donor cow.