• Proceedings of the Korean Institute of Surface Engineering Conference
• /
• 2016.11a
• /
• pp.152-152
• /
• 2016

Anodizing is a technology to generate thicker and high-quality films than natural oxide films by treating metals via electrochemical methods. It is a technique to develop metals for various uses, and extensive research on the commercial use has been performed for a long time. Aluminum anodic oxide (AAO) is generate oxide films, whose sizes and characteristics depending on the types of electrolytes, voltages, temperatures and time. Electrochemical manufacturing method of nano structure is an efficient technology in terms of cost reduction, high productivity and complicated shapes, which receives the spotlight in diverse areas. The sulfuric acid was used as an anodizing electrolyte, controlling its temperature to $10^{\circ}C$. The anode was 5083 Al alloy with dimension of $5(t){\times}20{\times}20mm$ while the cathode was the platinum. The distance between the anode and the cathode was maintained at 3 cm. Agitation was introduced by magnetic stirrer at 300 rpm to prevent localized temperature rise that hinders stable growth of oxide layer. In order to observe surface characteristics with applied current density, the electrolyte temperature, concentration was maintained at constant condition for $10^{\circ}C$, 10 vol.%, respectively. To prevent hindrance of stable growth of oxide layer due to local temperature increase during the experiment, stirring was maintained at constant rate. In addition, using galvanostatic method, it was maintained at current density of $10{\sim}30mA/cm^2$ for 40 minutes. The cavitation experiment was carried out with an ultrasonic vibratory apparatus using piezo-electric effect with modified ASTM-G32. The peak-to-peak amplitude was $30{\mu}m$ and the distance between the horn tip and specimen was 1 mm. The specimen after the experiment was cleaned in an ultrasonic, dried in a vacuum oven for more than 24 hours, and weighed with an electric balance. The surface damage morphology was observed with 3D analysis microscope. As a result of the investigation, differences were observed surface hardness and anti-cavitation characteristics depending on the development of oxide film with applied current density.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2001.05b
• /
• pp.42-45
• /
• 2001

The high permittivity are applied to DRAM and FRAM. (Ba,Sr)$TiO_3$ (EST) thin films were prepared by Sol-Gel method. BST solution was made and spin-coated on $Pt/SiO_2/Si$ substrate at 4000 [rpm] for 10 seconds in a time coating. Coated specimens were dried at $90[^{\circ}C]$ for 5 minutes. Coating process was repeated from 3 times to 5 times and then sintered at $750[^{\circ}C]$ for 30 minutes. Each specimen was analyzed structure and electrical characteristics. Thickness of BST ceramics thin films are about 2600-2800[$\AA$] in 3 times. Dielectric constant of thin films was little decreased at 1[KHz]~1[MHz]. Dielectric constant and loss to frequency were 250 and 0.02 in BST3. The property of leakage current was stable When the applied voltage was 0~3[V] Leakage current was $10^{9}\sim10^{11}$[A] at 0~3[V].

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2000.05b
• /
• pp.34-38
• /
• 2000

Recently, the ceramics of high permittivity are applied to DRAM and FRAM. In this study, (Ba, Sr)$TiO_3$ (BST) ceramics thin films were prepared by Sol-Gel method. BST solution was made and spin-coated on Pt/$SiO_2$/Si substrate at 4000 [rpm] for 10 seconds. Coated specimens were dried at $150[^{\circ}C]$ for 5 minutes. Coating process was repeated 3 times and then sintered at $750[^{\circ}C]$ for 30 minutes. Each specimen was analyzed structure and electrical characteristics by Fractal Process. Thickness of BST ceramics thin films are about $2000{\AA}$. Dielectric constant and loss of thin films was little decreased at 1[KHz] - 1[MHz]. Dielectric constant and loss to frequency were 250 and 0.02 in BST3. The property of leakage current as the realation between the current and the voltage was that change of the leakage current was stable when the applied voltage was 0~3[V].

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 1999.11a
• /
• pp.132-135
• /
• 1999

Recently, the ceramics of high permittivity are applied to DRAM and FRAM. In this study, (B $a_{x}$ S $r_{l-x}$)Ti $O_3$(BST) ceramics thin films were prepared by Sol-Gel method. BST solution was made and spin-coated on Pt/ $SiO_2$/Si substrate at 4000 [rpm] for 10 seconds. Coated specimens were dried at 150[$^{\circ}C$] for 5 minutes. Coating process was repeated 3 times and then sintered at 750[$^{\circ}C$] for 30 minutes. Each specimen was analyzed structure and electrical characteristics. Thickness of BST ceramics thin films are about 2000($\AA$). Dielectric constant and loss of thin films was little decreased at 1[KHz] ~1[KHz]. Dielectric constant and loss to frequency were 250 and 0.02 in $Ba_{0.7}$S $r_{0.3}$Ti $O_3$. The properly of leakage current as the realation between the current and the voltage was that change of the leakage current was stable when the applied voltage was 0~3[V].

• Journal of Advanced Navigation Technology
• /
• v.21 no.3
• /
• pp.220-229
• /
• 2017

In this paper, To take advantage a variety of DC power as the boost DC-DC converter design specifications through the inductor L and capacitor C through PSPICE to calculate the best estimate of the value. Boost DC-DC converter with a switch device using IRF840 and reverse recovery time Schottky diodes with excellent with constant current controller using D10SC6M and resistance can be configured to considering the Power LED Module was driven by the production. Converter's switching frequency is 50 kHz, the first Duty Rate was made to increase gradually depending on the value of the detection were, 10 % in the output voltage. As a result, the simulated Boost Power LED driver characteristics is in comparison with the design specifications, 5% or less as the error was approximated. Finally, when input 15 V were offered, a stable output 24 V were obtained. and Dimming Control through the adjustment of brightness and current consumption were possible.

• 전기의세계
• /
• v.15 no.4
• /
• pp.18-21
• /
• 1966

A transistorized counting-rate meter was designed by substituting one of diodes in the ordinary diode pumping circuit by the Darling's constant current source. Its circuit is so simple and stable that it is proper to use as a part of portable radiation detectors. Maximum readable counting rate is well above 100 kc/s and the linearity is very good. Output deviations due to the variations of embient temperatures are less than 5% in the temperatures from 20.deg. C to 40.deg. C.

• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.15 no.4
• /
• pp.191-198
• /
• 2015

The purpose of this study is to develope a current variation control system appropriate to the various LED(Light Emitting Diode) lamps using current control system equipped with microcontroller based voltage regulator of power driving circuit. For this, we will suggest a stable control system of current variation to enable a stable power-supply and current-control, consisting of circuit to minimize the affects on the LED forward voltage using variable resistance and compensating resistance. The method of constant current circuit and energy savings using microcontroller based voltage regulator suggested in this study can be applied to various a big capacity LED lamp to minimize the unnecessay heat generation and to control resistace delicately. Ultimately, we expect the results of this study will upgrade the reliability of LED lamp by supplying the current stably.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
• /
• v.11 no.5
• /
• pp.586-592
• /
• 2018

In this paper, HIC with various functions is proposed for the design 140W LED power control circuit. The proposed HIC integrates constant voltage/constant current circuit, short circuit protection circuit, internal constant voltage circuit, and dimmer circuit, thereby reducing the horizontal length of the PCB by 16% comparing with the conventional system. Through various experiments, we verified the performance of each block implemented inside of HIC with numerical results. (Constant voltage variation ratio: 2.9%, dimmer circuit duty variation within 5%, stable short protection at 720 mA) Since the PCB area can be significantly reduced by applying the proposed HIC. It is possible to reduce the PCB manufacturing time which takes up most of the manufacturing time, however, It is expected that the faulted power module can be replaced without replacing the whole PCB, so that maintenance / repair can be made easier.

• Journal of Environmental Science International
• /
• v.27 no.6
• /
• pp.467-475
• /
• 2018

The lifetime of the electrode is one of the most important factors on the stability of the electrode. Since the lifetime of the DSA (Dimensionally stable anode) electrode is long, an accelerated lifetime test is required to reduce the test time. Beacuse there is no basis or standard method for accelerated lifetime testing, many researchers use different methods. Therefore, there is a need for basis and methods for accelerated lifetime testing that other researchers can follow. We designed a reactor system for accelerated lifetime testing and planned specific methods. Reactor system was circulating batch reactor. Reactor volume and cooling water tank were 12.5 L and 100 L, respectively. Electrode size was $2cm{\times}3cm$ (real electrolysis area, $5cm^2$). In order to maintain the harsh conditions, accelerated lifetime test was carried out in a high current density ($0.6A/cm^2$) and low electrolyte concentration (NaCl, 0.068 mol/L). Maintaining a constant temperature was an important operation parameter for exact accelerated lifetime test. As the accelerated lifetime test progressed, the active component of electrode surface was consumed and desorption occurred. At the point of 5 V rise, corrosion of the surface of the base material(titanium) also started.

• Proceedings of the KIEE Conference
• /
• 1998.07f
• /
• pp.2148-2150
• /
• 1998

This paper proposes a constant frequency controlled zero voltage switching method that can reduce switching losses caused by emf on inductance in DC motor. The zero voltage switching method is used more than a zero current switching method because of reducing switching losses by capacitance of depletion region of MOSFET. To simplify the controller circuit, we propose constant frequency controlled zero voltage switching method in the paper. The control method is more stable than a variable frequency control method because it can optimize bandwidth of a closed-loop and reactances. Therefore, we construct a constant frequency controlled zero voltage switching converter and improve zero switching losses in high switching frequency. In the process, we can control low-losses in full range on variable voltage and load. We simulate the proposed converter with P-SPICE and compare results obtained through the experiment.