• Korean Journal of Biological Psychiatry
• /
• v.25 no.4
• /
• pp.89-100
• /
• 2018

Transcranial direct current stimulation (tDCS) is a non-invasive brain stimulation method that delivers 1-2 mA of current to the scalp. Several clinical studies have been conducted to confirm the therapeutic effect of major depressive disorder (MDD) patients with tDCS. Some studies have shown tDCS's antidepressant effect, while the others showed conflicting results in antidepressant effects. Our aim of this review is to understand the biological bases of tDCS's antidepressant effect and review the results of studies on tDCS's antidepressant effect. For the review and search process of MDD treatment using tDCS, the US National Library of Medicine search engine PubMed was used. In this review, we discuss the biological mechanism of tDCS's antidepressant effect and the existing published literature including meta-analysis, systematic review, control trial, open studies, and case reports of antidepressant effects and cognitive function improvement in patients with MDD are reviewed. We also discuss the appropriate tDCS protocol for MDD patients, factors predictive of response to tDCS treatment, the disadvantages of tDCS in MDD treatment, and side effects.

• Journal of The Korean Society of Integrative Medicine
• /
• v.11 no.1
• /
• pp.53-62
• /
• 2023

Purpose : This study evaluated the effects of transcranial direct current stimulation and a virtual reality program on the depression, hand functions, cognitive function, and activities of daily living of patients with mild cognitive impairment by dividing 20 patients with mild cognitive impairment and depression. The 20 patients were divided into a treatment group (transcranial direct current stimulation + a virtual reality program) and a control group (placebo transcranial direct current stimulation + a placebo virtual reality program). Methods : This study allocated ten subjects to the treatment group and ten subjects to the control group. The treatment was given five times per week for six weeks (30 sessions), and each session was 30 minutes. This study screened depression by using SGDS-K, a short geriatric depression scale, to examine depression before and after treatment intervention. This study also used the box and block test, NCSE, and FIM to evaluate hand functions, cognitive function, and activities of daily living, respectively. Results : The results showed that depression significantly decreased, hand functions significantly increased, cognitive function significantly improved, and activities of daily living significantly increased after intervention in the treatment and control groups. The magnitude of changes in depression, hand functions, cognitive function, and activities of daily living was significantly different between the two groups after intervention (p>.05). Conclusion : The results showed that the application of transcranial direct current stimulation and a virtual reality program could improve cognitive function, hand functions, and activities of daily living by decreasing depression. Therefore, it can be concluded that the simultaneous application of transcranial direct current stimulation and a virtual reality program is an intervention method, which can be applied for decreasing depression, enhancing hand functions, improving cognitive function, and increasing activities of daily living in patients with mild cognitive impairment.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.65 no.1
• /
• pp.232-238
• /
• 2016

This paper presents protection techniques against electric shock in low voltage DC(direct current) grounding systems depending on the analysis of earth fault current paths. Firstly, the comparison between alternating current and direct current on human was conducted, and current threshold values for each current path and for long duration were analyzed. Secondly, the analyses of the earth fault current flows were performed depending on the grounding types and earth fault conditions. Lastly, based on these analyses, adequate protection measures of electric shock depending on low voltage DC grounding types were provided.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.7 no.4
• /
• pp.719-724
• /
• 2003

In this paper, we have presented the simulation results about threshold voltage of nano scale lightly doped drain (LDD) MOSFET with halo doping profile. Device size is scaled down from 100nm to 40nm using generalized scaling. We have investigated the threshold voltage for constant field scaling and constant voltage scaling using the Van Dort Quantum Correction Model (QM) and direct tunneling current for each gate oxide thickness. We know that threshold voltage is decreasing in the constant field scaling and increasing in the constant voltage scaling when gate length is reducing, and direct tunneling current is increasing when gate oxide thickness is reducing. To minimize the roll off characteristics for threshold voltage of MOSFET with decreasing channel length, we know $\alpha$ value must be nearly 1 in the generalized scaling.

• Journal of International Academy of Physical Therapy Research
• /
• v.5 no.2
• /
• pp.752-756
• /
• 2014

This study investigated the effects of changes to the pulsation factor of pulsed direct currents on wound healing. Patients with a pressure ulcer at a care hospital for the elderly were randomly divided into three groups: Group 1 involved the application of $100{\mu}s$ in pulse duration, 10 ms in pulse period, 100 pps in a pulsation factor, 15 mA in pulse amplitude, and polarity red+ by using pulsed direct currents; Group 2 involved a change of pulse period to 8 ms; and Group 3 received general wound management. Although there were no statistically significant differences in the changing stages of pressure ulcers among the groups, all the groups dropped in numerical stages. In the two groups to which pulsed direct currents were applied, there was a statistically significant reduction in the stages of pressure ulcers from the initial assessment to the 12-week assessment (p<.05). Even though there were no statistically significant differences in changes to the area of pressure ulcers among the groups, a statistically significant decrease was found in pulsed direct current group 2 whose pulse period was shortened (p<.05). There was no difference in the healing rate of pressure ulcers among the groups, but it made a numerical increase in pulsed direct current group 1 and group 2 and a numerical decrease in group 3. There were no significant differences in the characteristics of those who had a full recovery among the groups. Those findings indicate that pulsed direct currents have positive effects on the wound healing of patients with a pressure ulcer and that a treatment with pulsed direct currents whose pulsation factor is raised by reducing the pulse duration is especially effective.

• Journal of the Korean Society for Nondestructive Testing
• /
• v.24 no.6
• /
• pp.566-572
• /
• 2004

It is necessary to measure the direct current with a non-contact methodology for the liquid or gas phase, as welt as the conducting metals. This paper described a theoretical consideration and experimental verification for a non-contact quantitative direct current measurement system using the Faraday effect and magnetic flux leakage. The leakage of magnetic flux occurs around a gap when a ferromagnetic core including the discontinuous gap is magnetized. Two large anisotropic domains in a magneto-optical film are occurred by the vertical component of leaked magnetic flux and the domain walls are paralleled to the center of the gap. Here, the symmetrical arrangement of domains are deflected when a vertical magnetic field is applied to the magneto-optical film. The domain wall of the magneto-optical film are relocated when a measuring current passes through the ferromagnetic core. Therefore, a direct current passing through the core can be determined quantitatively by the measurement of moving distance of the domain wall.

• Proceedings of the Materials Research Society of Korea Conference
• /
• 2010.05a
• /
• pp.49.2-49.2
• /
• 2010

Copper oxide films have been deposited on silicon substrates by direct current magnetron sputtering of Cu in O2 / Ar gas mixtures. The target oxidation occurring as a result of either adsorption or ion-plating of reactive gases to the target has a direct effect on the discharge current and the resulting composition of the deposited films. The kinetic model which relates the target oxidation to the discharge current was proposed, showing the one-to-one relationship between discharge current characteristics and film stoichiometry of the deposited films.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.23 no.6
• /
• pp.403-407
• /
• 2018

This study proposes a predictive direct power control method in a modular multilevel converter (MMC) high-voltage direct-current (HVDC) system. The conventional proportional integral (PI)-based control method uses a cascaded connection and requires an optimal gain selection procedure and additional decoupling scheme. However, the proposed control method has a simple structure for active/reactive power control due to the direct power control scheme and exhibits a fast dynamic response by predicting the future status of system variables and considering time delay. The effectiveness of the proposed method is verified by simulation results.

• Journal of the Korean Society of Marine Environment & Safety
• /
• v.24 no.2
• /
• pp.238-245
• /
• 2018

This paper proposes the applicability of matrix converter topology for the speed control of direct current motors. Matrix convertesr are divided into direct and indirect components. This paper utilizes an indirect matrix converter which is expected to be used widely because of making a variety of output side. The proposed converter has advantages which improves input current shape, has no large energy storage component causing short life. Simulation results are provided to verify effectiveness by comparing and analyzing features of the proposed and conventional topology. The proposed method shows similar performance for speed control, torque control, and load current control compared to a conventional method. Furthermore Harmonics are greatly reduced because the input current is controlled in a manner similar to sinusoidal wave by directly controlling switches at the rectifier stage.

• Journal of Sensor Science and Technology
• /
• v.30 no.2
• /
• pp.105-108
• /
• 2021

Detection and localization of partial discharge are considered critical techniques for estimating the lifetimes of power cables. High-frequency current transformers (HFCTs) are commonly used for the detection of partial discharge in high-voltage alternating current (HVAC) power cables; however, their applicability is compromised by the limitations of the installation locations. HFCTs are typically installed in cable terminals or insulation joint boxes because HVACs induce strong time-varying magnetic fields around the cables, saturating the ferromagnetic materials in the HFCTs. Therefore, partial discharges near the installation locations can be detected. In this study, the feasibility of partial discharge detection using a HFCT was investigated for high-voltage direct current (HVDC) cables. We demonstrated that the HFCT could be installed at any location in the HVDC power cable to monitor partial discharge along the entire cable length. Furthermore, we showed that the HFCT could detect the location of partial discharge with high accuracy.