Won Seok Choi

Synthesis and characterization of SnO2 :Sb film by dc magnetron sputtering method for applications to transparent electrodes

Transparent conducting Sb-doped SnO2 (antimony-doped tin oxide: ATO) films were prepared on Corning glass substrate by dc magnetron sputtering using SnO2 mixed with 6 wt.% of Sb at various substrate temperatures of 100–600 °C and dc powers of 100–200 W. All ATO films were deposited with a thickness of 300 nm. X-ray defractometer (XRD) measurements showed the ATO films to be crystallized with strong (101) orientation as substrate temperature increases over 300 °C. Grain size was calculated from the XRD spectra using the Scherrer equation. The ATO film in this work had a resistivity of order 10− 3 and carrier concentration of order 1020.

Separation of Acetic Acid from Acetic Acid-Water Mixture by Crystallization

Separation of acetic acid from acetic acid and water mixture was carried out by melt crystallization. The effect of the cooling rate, the amount of seeds, the seeding temperature, the sweating rate, and the sweating fraction on the distribution coefficient was investigated. The acetic acid was successfully separated by single-stage melt crystallization. As the sweating fraction is increased, the crystalline layers grown at lower cooling rates are purified more highly. Eventually, the crystallization rate is much more important than the sweating rate. The effective distribution coefficient ranges from 0.01 to 0.25 for the crystal growth rates of 1.2 × 10−6 m/s to 4 × 10−6 m/s.

SiC formation for a solar cell passivation layer using an RF magnetron co-sputtering system.

In this paper, we describe a method of amorphous silicon carbide film formation for a solar cell passivation layer. The film was deposited on p-type silicon (100) and glass substrates by an RF magnetron co-sputtering system using a Si target and a C target at a room-temperature condition. Several different SiC [Si1-xCx] film compositions were achieved by controlling the Si target power with a fixed C target power at 150 W. Then, structural, optical, and electrical properties of the Si1-xCx films were studied. The structural properties were investigated by transmission electron microscopy and secondary ion mass spectrometry. The optical properties were achieved by UV-visible spectroscopy and ellipsometry. The performance of Si1-xCx passivation was explored by carrier lifetime measurement.

Selecting Characteristic Raman Wavelengths to Distinguish Liquid Water, Water Vapor, and Ice Water

The Raman shift of water vapor is 3657 lTEXg

Implantable Bladder Sensors: A Methodological Review

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Structural and optical properties of a radio frequency magnetron-sputtered ZnO thin film with different growth angles.

l/TEXg, and this Raman signal can be easily separated from other Raman signals or elastic signals. However, it is difficult to make simultaneous Raman measurements on the three phases of water, namely, ice water, liquid water, and water vapor. This is because we must consider the overlap between their Raman spectra. Therefore, very few groups have attempted to make Raman simultaneous measurements even on two elements (water vapor and liquid water, or water vapor and ice water). We have made an effort to find three characteristic Raman wavelengths that correspond to the three phases of water after measuring full Raman spectra of water on particular days that are rainy, snowy or clear. Finally, we have found that the 401-nm, 404-nm, and 408-nm wavelengths are the most characteristic Raman wavelengths that are representative of the water phases when we are using the 355-nm laser wavelength for making measurements.

Investigation of X-Ray Photoelectron Spectroscopy and Electrical Conductivity Properties of the Layered Perovskite LnBaCo2O5+d (Ln = Pr, Nd, Sm, and Gd) for IT-SOFC

The loss of urinary bladder control/sensation, also known as urinary incontinence (UI), is a common clinical problem in autistic children, diabetics, and the elderly. UI not only causes discomfort for patients but may also lead to kidney failure, infections, and even death. The increase of bladder urine volume/pressure above normal ranges without sensation of UI patients necessitates the need for bladder sensors. Currently, a catheter-based sensor is introduced directly through the urethra into the bladder to measure pressure variations. Unfortunately, this method is inaccurate because measurement is affected by disturbances in catheter lines as well as delays in response time owing to the inertia of urine inside the bladder. Moreover, this technique can cause infection during prolonged use; hence, it is only suitable for short-term measurement. Development of discrete wireless implantable sensors to measure bladder volume/pressure would allow for long-term monitoring within the bladder, while maintaining the patient’s quality of life. With the recent advances in microfabrication, the size of implantable bladder sensors has been significantly reduced. However, microfabricated sensors face hostility from the bladder environment and require surgical intervention for implantation inside the bladder. Here, we explore the various types of implantable bladder sensors and current efforts to solve issues like hermeticity, biocompatibility, drift, telemetry, power, and compatibility issues with popular imaging tools such as computed tomography and magnetic resonance imaging. We also discuss some possible improvements/emerging trends in the design of an implantable bladder sensor.

Study for the Improvement of the Energy Storage System Efficiency Using Auto Level-Tuning Algorithm

This study introduces optical properties of a columnar structured zinc oxide [ZnO] antireflection coating for solar cells. We obtained ZnO films of columnar structure on glass substrates using a specially designed radio frequency magnetron sputtering system with different growth angles. Field-emission scanning electron microscopy was utilized to check the growth angles of the ZnO films which were controlled at 0°, 15°, and 30°. The film thickness was fixed at 100 nm to get a constant experiment condition. Grain sizes of the ZnO films were measured by X-ray diffraction. A UV-visible spectrometer was used to measure the transmittance and reflectance of the ZnO film columnar structures as a function of the growth angles.

Study on the Resonant HF DC/DC Converter for the Weight Reduction of the Auxiliary Power Supply of MAGLEV

Chemical states of the layered perovksite LnBaCo2O5+d (Ln = Pr, Nd, Sm, and Gd) are investigated using the x-ray Photoelectron Spectroscopy method. For the Co spectra of the LnBaCo2O5+d oxide systems, the two main peaks located at binding energies (BEs) of 779.65 eV and 794.96 eV are assigned to Co 2p3/2 and Co 2p1/2 of PrBaCo2O5+d (PBCO) and are ascribed to 779.86 eV and 795.08 eV of NdBaCo2O5+d (NBCO). In addition, the lower binding energy (LBE) and higher binding energy (HBE) of SmBaCo2O5+d (SBCO) were found to be 779.67 eV and 795.02 eV, respectively; the LBE and HBE of GdBaCo2O5+d (GBCO) were 779.73 eV and 795.03 eV, respectively. The BEs of the mixture state of Co3+ and Co4+ ions in PBCO, NBCO, SBCO, and GBCO were approximately located in the vicinity of 803.24 eV to 804.47 eV. As for the electrical conductivities of the layered perovskites, PBCO and NBCO had metallic characteristics over the whole temperature range tested while SBCO and GBCO exhibited metal-insulator transition (MIT) behavior.

Synthesis of zeolitic material from basalt rock and its adsorption properties for carbon dioxide

This paper is about control algorithms that bi-direction DC-DC Converter using Super Capacitor and regenerative power from DC feeding system in electrical train. In order to take advantage of regenerative energy efficient, charge and discharge level value of energy storage system serve as an important factor. Respect to output fluctuations of the substation and catenary voltage changing, we offers Charge-Discharge Auto Level Tuning Algorithms to improve system following of Energy Storage System.