• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2002.10b
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• pp.355-356
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• 2002

The dielectric permittance and the dielectric loss factor of several lubricating oils were measured at frequencies from 100 Hz to 1.5 MHz. The measurements were carried out under atmospheric pressure as a function of temperature and under fixed temperature as a function of pressure. Temperature and pressure dependence of dielectric relaxation time were investigated. The temperature dependence of relaxation time obeyed the Vogel-Fulcher-Tammann (VFT) law. We modified the VFT equation in order to express the dielectric relaxation time as a function of temperature and pressure. Furthermore. by taking into consideration the similarity of the temperature and pressure dependence between dielectric relaxation and mechanical relaxation. the prediction of high-pressure viscosity were conducted. The predicted results were compared with the viscosity data obtained from the falling-sphere type viscometer.

• Korean Journal of Biological Psychiatry
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• v.21 no.4
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• pp.175-181
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• 2014

Objectives It was the aim to examine the association of the thyroid-related hormones with cognitive function, depression, and subjective memory impairment in community-dwelling elders with questionable dementia. Methods The sample consisted of 399 community residents with 'questionable dementia' aged 60 or over in whom serum thyroid-related hormones [thyroid stimulating hormone (TSH) and thyroxine] had been assayed. Cognitive impairment was defined using the Korean version of the Consortium Establish a Registry for Alzheimer's Disease. Depression was diagnosed using the Korean version of Geriatric Depression Scale and subjective memory complaint (SMC) was checked using the subjective memory complaints questionnaire (SMCQ). Age, gender, education, and the presence of apolipoprotein E {\varepsilon}4 were included as covariates. Results There was a significant positive association between verbal fluency test (VFT) score and serum TSH levels (p = 0.01). There was a significant negative association between SMCQ total score and word list memory test (WLMT)(p = 0.002) or word list recall test (WLRT) score (p = 0.013). Conclusions Lower serum TSH levels were associated with semantic memory (VFT), and we found that SMC was associated with episodic memory (WLMT and WLRT) in this sample.

• The Journal of Korean Physical Therapy
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• v.27 no.6
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• pp.407-412
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• 2015

Purpose: This study aimed to evaluate changes in the balance ability of patients whose head positions were altered due to stroke. Subjects were divided into three groups to determine the effects of the training on dynamic balance and gait. Methods: Forty-two stroke patients were enrolled. The Visual Feedback Training (VFT) group performed four sets of exercises per training session using a Sensoneck device, while the Active Range of Motion (ART) group performed eight sets per training session after receiving education from an experienced therapist. The Visual Feedback with Active Range of Motion (VAT) group performed four sets of active range of motion and two sets of visual-feedback training per session using a Sensoneck device. The training sessions were conducted three days a week for eight weeks. Results: The comparison of changes in dynamic balance ability showed that a significant difference in the total distance of the body center was found in the VFT group (p<0.05) and Significant differences were found according to the training period (p<0.05). The comparison of the 10 m walk test showed that the main effect test, treatment period and interactions between group had statistically significant differences between the three groups (p<0.05). Conclusion: Head-adjustment training using visual feedback can improve the balance ability and gait of stroke patients. These results show that coordination training between the eyes and head with visual feedback exercises can be used as a treatment approach to affect postural control through various activities involving the central nervous system.

• The Journal of the Korea Contents Association
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• v.13 no.5
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• pp.322-331
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• 2013

The aim of this study was to investigate the effects of occupational therapy with physical exercise on executive function with dementia. For eight elderly persons with mild or moderate dementia, we executed physical exercise with group activity for 10 weeks from April to June, 2012, one times per week, and 50 minutes each time. Before and after the physical activities, the old adults were tested with Verbal Fluency Test(VFT), Trail Making Test A/B(TMT A/B), Clock Drawing Test(CDT). After the physical exercise, the subjects showed significant changes in the score of CDT(p<0.1). In contrast, there was no significant effect in VFT, TMT A. The results of this study show that occupational therapy with physical exercise program for demented elderly people is a useful therapeutic approach by enhancing the their quality of life through improving and maintaining their executive function.

• Journal of radiological science and technology
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• v.36 no.3
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• pp.209-217
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• 2013

Adiponectin (AdipoN), brain-derived nerotrophic factor (BDNF) and leptin (LeP) are mainly secreted from adipose tissue and are known to be involved in regulation of the development of obese. However, there are not many studies on the association between abdominal fat and neuropeptides such as AdipoN, BDNF and LeP. The aim of this study was undertaken to investigate the association between abdominal fat thickness, neuropeptides and cardiovascular disease (CVD) risk factors. The participants in the study were 138 male employees without CVD. This study was approved by the Institutional Review Board of Occupational Safety and Health Research Institute. Written informed consent for the participants in this study was obtained from all individuals. We obtained subcutaneous fat thickness (SFT) and visceral fat thickness (VFT) by using ultrasonography and neuropeptides levels were measured with ELISA kit according to the method suggested by kit manufacturer. The mean SFT and VFT were $1.58{\pm}0.51$ and $4.52{\pm}1.44$ cm. The mean concentrations of AdipoN, BDNF and LeP were $3.14{\pm}3.52$ ng/ml, $24.11{\pm}8.52$ pg/ml and $4.27{\pm}2.38$ ng/ml, respectively. VFT were positively correlated with total cholesterol (r=0.217, p<0.05), LDL-cholesterol (r=0.271, p<0.01), triglyceride (r=0.233, p<0.05) and insulin (r=0.338, p<0.01), but was inversely correlated with HDL-cholesterol (r=-420, p<0.01). AdipoN levels were positively correlated with HDL-cholesterol (r=0.220, p<0.05) and were inversely correlated with total cholesterol (r=-0.196, p<0.05), LDL-cholesterol (r=-0.190, p<0.05), triglyceride (r=-0.199, p<0.05), SFT (r=-0.195, p<0.05) and VFT (r=-0.412, p<0.01). However, LeP levels showed a reverse trend to AdipoN. AdipoN level was significantly higher in non-obese participants (BMI<25 kg/m), but LeP concentration was significantly higher in obese participants (BMI>25 kg/m) than in non-obese. On multiple logistic regression analysis, obese were significantly associated with AdipoN (odds ratio=0.784) and LeP (odds ratio=1.494). These results suggested that AdipoN and LeP concentrations are affected abdominal fat and that dysfunction and/or declination in the production and secretion of neuropeptides might induced ultimately obese and CVD.

• Journal of Electrical Engineering and Technology
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• v.8 no.1
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• pp.11-19
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• 2013

Very Fast Transients (VFT) originate mainly from disconnector switching operations in Gas Insulated Substations (GIS). In order to determine the rate-of-rise of Very Fast Transient Overvoltage (VFTO) in a 550 kV GIS, simulations are carried out using EMTP-RV. Each component of the GIS is modeled by distributed line model and lumped model based on equivalent circuits. The various switching conditions according to closing point-on-wave and trapped charge are simulated, and the results are analyzed. Also, the analysis of travelling wave using a lattice diagram is conducted to verify the simulation results.

• Journal of Communications and Networks
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• v.17 no.1
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• pp.1-11
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• 2015

In this paper, the transmission of an improper-complex second-order stationary data sequence is considered over a strictly band-limited frequency-selective channel. It is assumed that the transmitter employs linear modulation and that the channel output is corrupted by additive proper-complex cyclostationary noise. Under the average transmit power constraint, the problem of minimizing the mean-squared error at the output of a widely linear receiver is formulated in the time domain to find the optimal transmit and receive waveforms. The optimization problem is converted into a frequency-domain problem by using the vectorized Fourier transform technique and put into the form of a double minimization. First, the widely linear receiver is optimized that requires, unlike the linear receiver design with only one waveform, the design of two receive waveforms. Then, the optimal transmit waveform for the linear modulator is derived by introducing the notion of the impropriety frequency function of a discrete-time random process and by performing a line search combined with an iterative algorithm. The optimal solution shows that both the periodic spectral correlation due to the cyclostationarity and the symmetric spectral correlation about the origin due to the impropriety are well exploited.

• Proceedings of the Korea Society for Industrial Systems Conference
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• 2007.02a
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• pp.114-121
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• 2007

In the existing ISP methods, the important' role of enterprise value is usually ignored or not recognized in the information systems planning (ISP). Besides, in some ISP methods, there is a connotative precondition that the main body of value is always the enterprise stakeholder. Thus, in ISP, the enterprise stakeholders‘ value has been recognized while the value of other main bodies has been neglected, which has resulted in boycott and other problems in normalization construction. Based on the existing ISP analysis frame and ways, this article analyzes the enterprise fundamental principle of enterprise value acting on ISP and defines the formation of enterprise value. On the basis of Keeney's analysis way of value focused thinking for decision-making, we induct the factors of enterprise value into the ISP method and set forth such an ISP process: (1) identify the aggregation of enterprise value; (2) conform the objective structure of enterprise levels; (3) determine the appraisal standard for enterprise fundamental objectives; (4) determine the basic structure for information systems ; (5) confirm the data requirements for information systems; (6) give appraisal and comment.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37A no.11
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• pp.979-985
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• 2012

The design of an efficient scheduler is a key design factor in IEEE 802.16m systems, in order to support services with various QoS smoothly. Although conventional studies of schedules have been suggested, those had problems that are not able to satisfy the delay condition and make the through-put declined, because they only focused on a specific action scenario rather than reflecting practical action scenarios which have real-time and non-real-time traffics variously. In this paper, an efficient uplink scheduling algorithm is proposed for IEEE 802.16m system by introducing the concepts of Virtual Time(VT) and Virtual Finish Time(VFT) based priority determination, and separate buffers for each QoS class in the mobile terminal. Simulation results showed that the proposed scheme had satisfied the delay requirement of real-time services even with improved throughput performance compared to conventional methods.

• Journal of radiological science and technology
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• v.31 no.3
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• pp.249-258
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• 2008

Purpose : Abdominal obesity with visceral fat accumulation have been known to be intimately associated with the development of metabolic syndrome. Therefore, it is important to estimate the precise amount of visceral fat. Ultrasonography has been reported that it is a simple and noninvasive method for visceral fat evaluation. Purpose of this study is to evaluate the association of ultrasonographic visceral fat thickness, anthropometric indexes, and risk factor of metabolic syndrome, and to investigate the cut-off value of abdominal visceral fat thickness leading to increased risk of metabolic syndrome. Materials and methods : The subject included 200 men and 200 women who visited D healthcare center in Daejeon from January to April 2008. The subcutaneous fat thickness and visceral fat thickness were measured by ultrasonograph. As anthropometric index, we measured body mass index, waist circumference and waist/height ratio. As for the risk factor of metabolic syndrome, we measured blood pressure, high density lipoprotein cholesterol, triglyceride and fasting serum glucose. Results : VFT was significantly correlated with waist circumference, (r=0.683/M, r=0.604/F), waist to height ratio (r=0.633/M, r=0.593/F) and BMI (r=0.621/M, r=0.534/F) in both men and women. In addition it was significantly correlated with Systolic blood pressure (r=0.229/M, r=0.232/F), Diastolic blood pressure ((r=0.285/M, r=0.254/F), high density cholesterol (r=-0.254/M, r=-0.254/F), Triglyceride (r=0.475/M, r=0.411/F), and Fasting blood sugar (r=0.158/M, r=0.234/F) in both men and women. The cut-off value of visceral fat thickness leading to the increased risk of metabolic syndrome was 4.58cm (sensitivity89.2%, specificity 71.2%) in men and 3.50cm (sensitivity61.2% specificity 80.8%) in women respectively. The odds ratio of the risk of metabolic syndrome was dramatically increased with the abdominal visceral fat thickness level over 6cm in men and 5cm in women. Conclusion : The visceral fat thickness using ultrasonography was significantly correlated with anthropometric indexes and risk factors of metabolic syndrome in both men and women. The cut-off value of visceral fat thickness leading to the increased risk of metabolic syndrome was 4.58cm in men and 3.50cm in women.