• The Korean Journal of Ecology
• /
• 제16권1호
• /
• pp.17-26
• /
• 1993

We investigated the ph change of water caused by several fuel gases regarded as the main cause of the air pollution, To find out the main cause of increase of the acidity of the rain. We measured it while injrcting each fuel gas directiy to the distilled water. It was observed that bunker-c oil gas and anthracite coal gas were the main cause to make the ph of the solution lowest. We examined the effects of simulated acidic water solutions on several plant species. Simulated acidic rain made by bunker-c oil gas has significant symptom on the saxifraga stolonifera and commelina communis, while no injury was observed on plants exposed to simulated rainfall made by anthracite coal gas.

• JSTS:Journal of Semiconductor Technology and Science
• /
• 제15권1호
• /
• pp.16-21
• /
• 2015

In this study, the effects of forming gas post metallization annealing (PMA) on recessed AlGaN/GaN-on-Si MOSHFET were investigated. The device employed an ICPCVD $SiO_2$ film as a gate oxide layer on which a Ni/Au gate was evaporated. The PMA process was carried out at $350^{\circ}C$ in forming gas ambient. It was found that the device instability was improved with significant reduction in interface trap density by forming gas PMA.

• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2004년도 추계학술대회
• /
• pp.1664-1669
• /
• 2004

Design analysis of the solid oxide fuel cell and gas turbine combined power system is performed considering different methods for preheating cell inlet air. The purpose of air preheating is to keep the temperature difference between cell inlet and outlet within a practical design range. Three different methods are considered such as a burner in front of the cell, a preheater in front of the cell and recirculation of the cathode exit gas. Analyses are carried out for two maximum cell temperature differences. The greater temperature difference ensures higher efficiency. The cathode exit gas recirculation exhibits better performance than other methods.

• 한국유체기계학회 논문집
• /
• 제3권1호
• /
• pp.37-42
• /
• 2000

Analytical and experimental investigations have been carried out on the gas pulsations in the discharge paths of a high-side horizontal scroll compressor, where the gas discharged from compression chamber is made to pass through several chambers inside the compressor shell. Model of Helmholtz resonators in series has been applied to this configuration to predict gas pulsation phenomena along the passages, and the calculation results have been compared with measured pressure time traces. Good agreements between the analytical and experimental results have been obtained. It has also been found that the compressor performance is somewhat affected by the size of individual chambers inside the compressor shell.

• 한국공작기계학회논문집
• /
• 제12권1호
• /
• pp.24-31
• /
• 2003

In the gas cutting of plate steel, the quality of the cut surfaces and sections is strongly dependent on the cutting conditions such as cutting speed, kerf width, plate thickness, material, distance between tip and specimen, and cutting oxygen pressure etc. The cutting tests of plate steel were carried out using CNC gas cutting machine. This paper deals with cut surface and section characteristics of plate steel in CNC gas cutting. Both top and bottom widths of kerf, the surface roughness(Ra, Rmax) of cutting surfaces are measured under various cutting conditions such as cutting speed, material, distance between tip and specimen, and cutting thickness. The photographs of cut surface and cut section are also analyzed under various cutting conditions.

• 한국세라믹학회지
• /
• 제42권1호
• /
• pp.11-15
• /
• 2005

The configuration of the main components and the physical structure of the Taguchi sensor, the first ceramic gas sensor mass produced, has remained virtually unaltered since its appearance 40 years ago. This device owns an excellent combination of the quality factors but is non-selective. The research efforts carried out to enhance the selectivity in this resistive gas sensor are briefly reviewed. A novel design, Capillary-attached Gas Sensor (CGS), is introduced, which employs the same ceramic components used for the fabrication of a classical Taguchi sensor but in altered geometries. CGS presents remarkable advantages from the view point of selectivity over the original design. While the steady state response of a CGS has the same significance as that of the Taguchi sensor, its transient response presents valuable diagnostic information. Fabrication and test of a prototype CGS is reported.

• Journal of Electrical Engineering and Technology
• /
• 제2권3호
• /
• pp.306-311
• /
• 2007

The transient fields generated during switching operations in a Gas Insulated Substation (GIS) are associated with high frequency components in the order of few tens of MHz. These transient fields leak into the external environment of the gas-insulated equipment and can interfere with the nearby electronics. Measurements of the transient fields are thus required to characterise the interference caused by switching phenomena in such substations. In view of the above, E-field emission measurement during a switching operation has been carried out for a 245 kV GIS model, using a resonant dipole antenna and D-dot sensor. The characteristics of the E-fields i.e., frequency spectra and their levels have been analysed and are reported in the paper. Suitability of the measurements has been confirmed by comparing frequency spectra of the measured and computed transient fields.

• Journal of Advanced Marine Engineering and Technology
• /
• 제32권3호
• /
• pp.455-460
• /
• 2008

The flammable gas monitoring system is to be provided in cargo pump rooms of tankers in accordance with the requirements of SOLAS regulations, and flammable gas detectors are to be arranged in a proper position. In this paper, simulation tests and CFD analysis are carried out under the actual ventilation conditions of pump rooms in the ship in service. Based on the results, a new guidelines for an arrangement of flammable gas detectors are suggested.

• 신재생에너지
• /
• 제4권1호
• /
• pp.37-43
• /
• 2008

As the distributed generation becomes more reliable and economically feasible, it is expected that a higher application of the distributed generation units would be interconnected to the existing grids. This paper describes the results for the mechanical and environmental tests of pretreatment system material. Mechanical Characteristics make differences between parent / weldment, Notch existence / non-existence and air/$H_2O$ conditions. As a result, the life of pipe lines needs to maintain and fit for the operating period. Based on actual situations, the tension test of pipe welding-parts is carried out varying the exposure time of hydrogen sulfide and the fatigue resistance test is also performed inserting a notch into the pipe welding part, being exposed to the hydrogen sulfide environment for 720 hours.

• Environmental Analysis Health and Toxicology
• /
• 제6권3_4호
• /
• pp.123-132
• /
• 1991

Acute poisoning with organic solvents and other volatile compounds now usually follows deliberate inhalation (volatile substance abuse) or ingestion of these compounds. The effect of butane gas inhalation was analyzed for serum, liver, brain, lung and muscle. And the observations are revealed on rat cholinesterase activity, lactatedehydrogenase activity and electrophoretic pattern of lactatedehydrogenase isozyme. The results are as follows: 1. The rat cholinesterase activity on serum, liver and muscle show the decreased by increasing of inhalation time of butane gas in particular the lung cholinesterase activity was greatly affected. 2. Butane gas inhalation brought out the lactatedehydrogenase activity increased of the serum and the tissues and had an important effect especially in both the liver and muscle 1actatedehydrogenase activities. 3. Each tissue was found to have a characteristic distribution of lactatedehy-drogenase isozymes on celluloseacetate electrophoresis and the development of inhalation time is shown the disappearance and diffusion of band. The toxicity of butane gas inhalation was most prominence in the liver and lung toxicity was occurred also.