• Journal of the Korean Academy of Clinical Electrophysiology
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• v.9 no.1
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• pp.15-21
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• 2011

Purpose : This study aims to examine the effects of action observation of ski simulation on electroencephalogram (EEG). Methods : Thirty healthy subjects were randomly divided into three groups: 10 participants in an AM (actual movement) group; 10 participants in an OM (observation) group; and 10 participants in a CM (control movement) group. The EEG was measured to examine changes in EEG between action observation and actually movement at 8 areas of the scalp for one minute before, during and after action observation. Results : Relative alpha power showed statistically significant differences among groups in Cz and C4 and there were interactions among groups in the Oz area. Relative beta power showed no statistical significance among groups and in particular, there were interactions among groups in the Oz area. Conclusion : These findings show that action observation affected brain activation as in actual movement. Thus it can be expected that when movement through the brain activation is applied to patients in bed rest or those who cannot perform actually movement, it can be utilized as physiotherapy.

• Journal of the Korean Academy of Clinical Electrophysiology
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• v.9 no.2
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• pp.25-30
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• 2011

Purpose : This study aims to examine the changes of muscle activity of the tibialis anterior muscle and the gastrocnemius muscle on the ground and unstable ground for functional reach test. Methods : This study chose 24 elderly men and 24 elderly women who could walk independently, reach their arm over 25 cm, show shoulder joint $90^{\circ}$ flexion, had no operations on lower limb joints, and don't take medication affecting the ability to keep balance. Muscular activity of the tibialis anterior muscle and the gastrocnemius muscle was measured using functional reach test and electromyogram. Functional reach test was conducted at a total of four sections, 0cm, 15cm, 20cm, and 25cm. Results : It was known that the gastrocnemius muscle was used more than the tibialis anterior muscle to keep balance and the elderly with good balance ability showed no great change of muscular activity on both the stable and unstable ground. Conclusion : It was found that the subjects used their gastrocnemius muscle more and lower limbs of frequently used parts to keep their balance. As the elderly have good balance ability, they showed no great change of muscular activity on both the stable and unstable ground.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
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• v.6 no.2
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• pp.1-7
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• 2010

The objective of this study is to find the optimal control algorithm of a hybrid Plant, which is combined by renewable energy plant of the GSHP(Geothermal Source Heat Pump) and the normal plant (Chiller, boiler). The work presented in this study was carried out in the EnergyPlus(Version 2.0). The EnergyPlus was modified in order to simulate the hybrid plant. The plant system was controlled by the load-range-based operation in which schemes select a user specified set of equipment for each user specified range of a particular simulation condition. In the use of the load-range-based operation, four kind of control cases were defined and simulated in order to obtain the optimal control algorithm of the hybrid plant. The result showed that the Case 2 was the optimal control algorithm which used the GSHP as a base operating plant and the normal plant as an assistant operating plant. Even though the normal plant was operated in full load and the renewable energy plant of the GSHP was operated in partial load, the annual energy consumption of the normal plant was larger than that of the GSHP plant.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.11a
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• pp.636-639
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• 2004

This paper presents the fabrication and performance evaluation of zinc oxide varistors for the arresters used for station system. ZnO varistors were fabricated with typical ceramic production methods and the structural and electrical characteristics were investigated. All varistors exhibited high density, which were in the range of $5.41{\sim}5.49g/cm^3$. In the electrical properties the reference voltage increased in the range of $4.410{\sim}5.250kV$ with increasing their thickness and the residual voltage exhibited the same trends as the reference voltage. In the long duration current impulse withstand test, E-2 and F-1 samples failed in the two and four shots, respectively, but E-1 and F-2 samples survived 18 shots during the test. Before and after this test, the variation ratio of residual voltage of E-1 and F-2 samples were -0.34% and 0.05%, respectively, which were in the acceptance range of 5%. According to the results of tests, it is thought that if the fabrication process such as insulating coating, sintering condition, and soldering method is improved, these ZnO varistors would be possible to apply to the station class arresters in the new future.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.07b
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• pp.1168-1171
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• 2003

In contrast to a conventional transformer, the flat transformer is made using a number of small ferrite cores. Two cores for transformer and one core for inductor, which composed one module. Many modules can be connected together to form a flat matrix transformer. This structural arrangement eliminates the single hot spot problem in conventional transformers and permits high current density pertains at high frequency. In this study, the ferrite magnetic cores of Mn-Zn system for the Flat transformer were manufactured and the electrical and magnetic characteristics of its tested. The power loss of sample FO2(Mn-Zn ferrite) sintered at $1350^{\circ}C$ was $350kW/m^3$ in test conditions of 250kHz, 200mT and $100^{\circ}C$, which showed the good power loss property in high frequency. The power loss of FO2 samples has been studied as a function of magnetic flux density and frequency. Steinmetz exponent was 2.82 at 250kHz and 2.73 at 500kHz. These results illustrated the switching of power loss mechanism in ferrite core from hysteresis losses to eddy current losses or others.

• Journal of the Korea Concrete Institute
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• v.19 no.4
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• pp.483-490
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• 2007

Traditional external post-tensioning method using either steel bars or tendons is commonly used as a retrofitting method for concrete bridges. However, the external post-tensioning method has some disadvantages such as stress concentration at anchorages and inefficient load carrying capability regarding live loads. Thermal prestressing method is a newly proposed method for strengthening and rehabilitation of concrete girder bridges. Founded on a simple concept of thermal expansion and contraction of steel, the method is a hybrid method of external post-tensioning and steel plate bonding, combining the merits of two methods. In this paper, basic concepts of the method are presented and an illustrative experiment is introduced. From actual experimental data, the thermal prestressing effect is substantiated and the FEM approach for its analysis is verified.

• The Korean Journal of Financial Management
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• v.20 no.1
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• pp.61-92
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• 2003

As an extension of previous researches with the conclusion that the announcement of adopting stock options generates positive abnormal returns, this paper examined whether the abnormal return changes over time or varies depending on the number of stock options granted. Empirical analysis was made to find whether the announcement of stock option awards has the same response in the stock market from the early days when stock option plans had been introduced in the Korean stock market till today when it was widespread. Results indicate that the announcement effect had been on a gradual decline since 2000. In addition, it is found that if a company announces stock option awards several times, the abnormal return gradually declines in proportion of the number of stock options granted. This implies that as the stock option awards become widespread, the positive effect that the announcement of adopting stock options generates as news has been on a relatively steady decrease. In short, it leads to a conclusion that the more companies grant stock options, and the more stock options a company announces, the less impact it has on the increase in the firm's value.

• Korean Journal of Biological Psychiatry
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• v.22 no.4
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• pp.216-222
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• 2015

Objectives The principal aim of the present study was to investigate the characteristic depressive symptoms in patients with social anxiety disorder (SAD) and panic disorder in comparison to patients with depressive disorder. Methods This study included 132 patients with SAD, 128 panic disorder and 64 depressive disorder (major depressive disorder, dysthymia etc.) patients without comorbid psychiatric disorders. The Beck Depressive Inventory (BDI) is used to measure depressive symptoms. We divided BDI into three categories originally described by Shafer AB, including negative attitude toward self, performance impairment, and somatic symptoms. We compared the depressive symptoms of SAD, panic disorder and depressive disorder by using ANOVA. Results Negative attitude toward self was noticeable in SAD (SAD $0.54{\pm}0.23$, panic disorder $0.41{\pm}0.17$, depressive disorder $0.46{\pm}0.11$, p < 0.001). Performance impairment and somatic symptoms were remarkable in panic disorder than in SAD and depressive disorder (performance impairment : SAD $0.39{\pm}0.21$, panic disorder $0.44{\pm}0.14$, depressive disorder $0.40{\pm}0.09$, p = 0.009 ; somatic symptoms : SAD $0.07{\pm}0.10$, panic disorder $0.15{\pm}0.12$, depressive disorder $0.14{\pm}0.08$, p < 0.001). Conclusions The results facilitate an approach to optimal treatment for patients with comorbidity of anxiety disorder and depression.

• Korean Journal of Biological Psychiatry
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• v.14 no.1
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• pp.55-60
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• 2007

Objectives : There have been many association studies of panic disorder. However, studies about the dopaminergic function in panic disorder have been few. This study was aimed to examine the possible association of dopamine transporter gene(DAT1) polymorphism and panic disorder in Korean population. Methods : Ninety-eight patients with panic disorder(43 male(46.9%), mean age $42.13{\pm}10.88$ years) and one hundred and thirteen comparison subjects(67 male(40.7%), mean age $33.14{\pm}8.55$ years) were tested for DAT1 polymorphism. Genotypes of DAT1 with variable number of tandem repeats(VNTR) were determined using polymerase chain reaction. The differences of allelic frequency and genotype frequency distribution between patient and the control group were tested with Fisher-Freeman-Halton test. Results : There was association between DAT1 polymorphism and panic disorder(allele : p<0.03, genotype : p<0.05). The frequency of 10/10 homozygotes of DAT1 was significantly higher in control group(${\chi}^2$=4.452, df=1, p=0.035). Conclusion : These results in our Korean samples suggest that DAT1 polymorphism might be associated with the vulnerability of panic disorder. Possible association of dopaminergic genes and panic disorder should be investigated with future studies using larger and different population.

• Transactions of the Korean Society of Mechanical Engineers
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• v.8 no.2
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• pp.154-161
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• 1984

A modified technique of the transient hot wire method to measure the thermal conductivity of fluid has been described in this paper. The thermal conductivity of fluid can be obtained by acquiring wire temperature as a function of time. Multiplication of the inverse slope of the temperature versus logarithm of time by an instrumental constant gives the thermal conductivity. The constant voltage was applied to Wheatstone bridge circuit. The wire temperature can be measured as a function of time precisely with the aid of the data acquisition system composed of a microprocessor and an analog-digital converter. The thermal conductivity of the electrically conducting fluid has been measured with the insulated hot wire coated by electrically non-conducting material. The effect of the coated insulation layer on the thermal conductivity has been examined, in which it is confirmed that the thermal conductivity of electrically conducting liquid can be determined by the transient coated hot wire method. Thermal conductivities of methanol, carbontetrachrolide, Freon-22 and glycerin have been measured at room temperature in the pressure from 0.1MPa to 35.1MPa. The experiment has been performed to compare the data from the bare and the coated wires, and the results are satisfactory.