• Journal of Environmental Science International
• /
• v.5 no.3
• /
• pp.285-295
• /
• 1996

In genneral, Businger expression is used for determining a turbulance diffusion coefficient. In this study, it is applied to the surface elements of cities such as Asphalt, Cround, Grass, Pond. We set up 5 m-height bar and measured the ary temperature and wet temperature at 도 height of 0.13, 0.27, 0.5, 1, 0, 3.0, 5.0m. In addition we measured the wind gradient and wind velocity at the height 3 m solar radiation continuously for 48 hours on the surface. Compared the measured data to Businger expression the result showed that Businger expression can be well applied to the complex surface of the city.

• Journal of Korea Technical Association of The Pulp and Paper Industry
• /
• v.31 no.3
• /
• pp.60-67
• /
• 1999

The CLSM and the image analysis technique enhanced observation of fiber wall fibrillation occurred in both the outer and the fiber wall surfaces during refining by non-destructive techniques. In the early stages of refining, it was well observed that a partial separation between the S1 and S2 layer in the secondary wall was made generating a space in the wet fiber walls . With further refining, it was clearly shown that the shear forces imparted by the refiner bar surfaces caused the S1 layer to become totally separated from the S2 layer as well as creating microfibrils. Furthermore, the fibrillation in the inner fiber wall surfaces could be due to the normal force (Fn) by refiner bars, friction force between a fiber and refiner bars (Fs) and inner friction force between fiber walls(fs). It was confirmed that the concept of fibrillation should be extended to fibrillation in the inner fiber wall surfaces as well as internal and external fribrillation.

• Journal of Korea Technical Association of The Pulp and Paper Industry
• /
• v.32 no.3
• /
• pp.1-9
• /
• 2000

The MDDA (Modified Dynamic Drainage Analyzer) was developed to evaluate the drainage characteristics on paper machine. The initial forming vacuum velocity was decreased with the increase of stock consistency and there were no significant effects of the applied vac-uum. On the other hand the initial forming drainage velocity was rapidly decreased with the increase of stock consistency above the 0.35 bar of applied vacuum. The final drainage time and wet web permeability showed similar trends under 0.075% consistency but increased rapidly at the higher consistencies. SFR(Specific Filtration Resistance) and drainage obtained for different vacuum level applied and deposited weights measured by using MDDA showed the linear relationship.

• Nuclear Engineering and Technology
• /
• v.54 no.12
• /
• pp.4620-4624
• /
• 2022

Several cadmium zinc telluride (CZT) crystals were fabricated into radiation detectors using methods that included slicing, dicing, lapping, polishing, and chemical etching. A wet passivation with sodium hypochlorite (NaOCl) was then carried out on the Br-etched detectors. The Te-rich layer on the CZT surface was successfully compensated to the Te oxide layer, which was analyzed with X-ray photoelectron spectroscopy data of both a Br-etched crystal and a passivated CZT crystals. We confirmed that passivation with NaOCl improved the transport property by analyzing the mobility-lifetime product and surface recombination velocity. The electrical and spectroscopic properties of large volume detectors were compared before and after passivation, and then the detectors were observed for a month. Both bar and quasi-hemispherical detectors show an enhancement in performance after passivation. Thus, we could identify the effect of NaOCl passivation on large volume CZT detectors.

• Korean Chemical Engineering Research
• /
• v.43 no.1
• /
• pp.27-32
• /
• 2005

We propose an effective and environmentally friendly dry stripping method using a supercritical carbon dioxide ($SCCO_2$) system modified by a single and multiple cosolvents to remove ion-implanted photoresist and residue from a wafer surface at three different temperatures (97, 148, $200^{\circ}C$) and pressures (200, 300, 400 bar). After high dose of ion implantation the photoresist was not easily removed by using pure $SCCO_2$, but swollen. The $SCCO_2$ system modified by single cosolvents and multiple cosolvents mixed with aprotic solvents could not effectively remove the heavy organics, but swell them. However, the $SCCO_2$ system modified with multiple cosolvent (5%, v/v) composed of DMSO and DIW showed high removal efficiency for ion-implanted photoresists at $97^{\circ}C$ and 200 bar for 30 min (about 80%). In this study it has been shown that the dry stripping method using $SCCO_2$ system modified with multiple cosolvents could replace either plasma ashing or acid and solvent wet bench method and dramatically reduce accompanied chemical usage and disposal.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2008.11a
• /
• pp.953-956
• /
• 2008

The present study was to develop a dry PFB method similar to the existing gypsum board construction method in order to apply the existing wet PFB method that uses fire.resistant adhesive. It was found that the existing wet method can produce concrete compressive strength of 80MPa and fire resistance of 3 hours with 30mm PF boards. The goal of development in this study was fire resistance of 3 hours through dry construction of 15mm fire.resistant boards.According to the results of fire resistance test, when the dry PF method was applied, the temperature of the main reinforcing bar was 116$^{\circ}$C in 15mm, 103.8$^{\circ}$C in 20mm, and 94$^{\circ}$C in 25mm, and these results satisfied the current standards for fire resistance control presented by the Ministry of Land, Transport and Maritime Affairs. When a 3.hour fire resistance test was performed and the external properties of the specimen were examined, the outermost gypsum board hardly remained and internal PF board maintained its form without thermal strain.

• Journal of the Institute of Electronics Engineers of Korea SC
• /
• v.42 no.6
• /
• pp.67-76
• /
• 2005

This paper proposes a compact-sized surface myoelectric sensor for the myoelectric hand prosthesis. To fit the surface myoelectric sensor in the socket for the myoelectric hand prosthesis, the sensor should be a compact size. The surface myoelectric sensor is. composed of a skin interface and a single processing circuit that are mounted on a single package. The skin interface has one reference and two input electrodes, and the reference electrode is located in the center of two input electrodes. In this paper we propose two types of sensors with the circle- and bar-shaped reference electrode, but all input electrodes are the bar-shaped. The metal material of the electrodes is the stainless steel (SUS440) that endures sweat and wet conditions. Considering the conduction velocity and the median frequency of the myoelectric signal, we select the inter-electrode distance (IED) between two input electrodes as 18mm, 20mm, and 22 mm. The signal processing circuit consists of a differential amplifier with a band pass filter, a band rejection filter for rejecting 60Hz power-line noise, amplifiers, and a mean absolute value circuit. We evaluate the proposed sensor from the output characteristics according to the IED and the shape of the reference electrode. From the experimental results we show the surface myoelectric sensor with the 18mm IED and the bar-shaped reference electrode is suitable for the myoelectric hand prosthesis.

• Proceedings of the Korea Concrete Institute Conference
• /
• 1995.04a
• /
• pp.396-401
• /
• 1995

Epoxy coated reinforcing steels (ECRs) were acquired from ten sources and coatings from each source were initially characterized in terms of defects, thickness, solvent extraction weight loss and hardness. Testing involved exposure in three aqueous solutions at elevated temperature (8$0^{\circ}C$) and in chloride-contaminated concrete slabs under outdoor exposure, It was found that the density and size of coating defects was the promary factor affecting ECR performance. The equivalent circuit analysis using electrochemical impedance spectroscopy (EIS) data indicated that the impedance response for well-performing ECR specimens showed no signs of active degradation at the interface although diffusional processes similar to those noted for poorly performing bars occurred here. Experimental results also indicated a relationship between corrosion behavior and bar source. Weight loss upon solvent extraction correlated with impedance reduction from hot water exposure. Coating defects during most of the tests, especially in high pH solutions containing chloride ions. ECRs with excessive coating defects, either initially present or ones which developed in service, performed poorly in every test category regardless of source. Forms of coating failure were extensive rusting at defects, blistering, wet adhesion loss, cathodic delamination, underfilm corrosion and coating cracks. These occurred sequentially or concurrently, depending on the condition of the ECR and nature of the environment

• Transactions of the Society of Information Storage Systems
• /
• v.1 no.2
• /
• pp.182-187
• /
• 2005

A large area micro mirror is an optical element that functions as changing an optical path by reflection in integrated optical system. We fabricated the large area silicon mirror by anisotropic etching using MEMS for implementation of integrated optical pickup. In this work, we report the optimum conditions to better fabricate and design, greatly improve mirror surface quality. To obtain mirror surface of $45^{\circ},\;9.74^{\circ}$ off-axis silicon wafer from (100) plane was used in etching condition of $80^{\circ}C$ with 40wt.% KOH solution. After wet etching, polishing process by MR fluid was applied to mirror surface for reduction of roughness. In the next step, after polymer coating on the polished Si wafer, the Si mirror was fabricated by UV curing using a trapezoid bar-type way structure. Finally, we obtained peak to valley roughness about 50 nm in large area of $mm^2$ and it is applicable to optical pickup using blu-ray wavelength as well as infrared wavelength.

• Journal of the Korean institute of surface engineering
• /
• v.37 no.6
• /
• pp.344-349
• /
• 2004

Emulsions were formed through putting small quantity of nickel electroplating solution into supercritical carbon dioxide, and then electroplating in the $sc-CO_2$ emulsions was conducted. It is an environmental-friendly technology that can solve the treatment of a large quantity of toxic plating wastewater, which is a big problem in the existing wet plating, and also can reduce secondary waste generation fundamentally. Supercritical carbon dioxide emulsions enhanced by ultrasonic horn were formed by non-ionic surfactant and nickel solution. Plating condition within emulsions was set up as 120bar and $55^{\circ}C$ through measurement of electrical conductivity following the pressure change. Experiments were conducted respectively against supercritical carbon dioxide emulsions electroplating and general chemical electroplating, and then their results were compared and analyzed. As the experiment result utilizing emulsions, plating surface was formed very evenly even with a small quantity of electroplating solution, and fine particles were plated compactly without any pinhole or crack due to hydrogenation, which occurs in general electroplating. Used electroplating solution can be reused through recovery process. Therefore, this technology will be able to be applied as new clean technology in electro-plating.