• Journal of IKEEE
• /
• v.17 no.1
• /
• pp.71-76
• /
• 2013

AlGaN/GaN HEMTs (High electron mobility transistors) with narrow channel were fabricated and the effect of channel scaling on the device were investigated. The devices were fabricated using e-beam lithography to have same channel length of $1{\mu}m$ and various channel width from 0.5 to $9{\mu}m$. The sheet resistance of the channel was increased corresponding to the decrease of channel width and the increase was larger at the width of sub-${\mu}m$. The threshold voltage of the HEMT with $1.6{\mu}m$ and $9{\mu}m$ channel width was -2.85 V. The transistor showed a variation of 50 mV at the width of $0.9{\mu}m$ and the variation 350 mV at $0.5{\mu}m$. The transconductance of 250 mS/mm was decreased to 150 mS/mm corresponding to the decrease of channel width. Also, the gate leakage current of the HEMT decreased with channel width. But the degree of was reduced at the width of sub-${\mu}m$. It was thought that the variation of the electrical characteristics of the HEMT corresponding to the channel width came from the reduced Piezoelectric field of the AlGaN/GaN structure by the strain relief.

• Journal of Aquaculture
• /
• v.20 no.2
• /
• pp.106-113
• /
• 2007

Biological characteristics of Philasteridies dicentrarchi (Ciliophora:Scuticociliate) isolated from the cultured olive flounder Paralichthys olivaceus was determined out by culture, growth conditions, and in vitro relief effect of chemical compounds. The scuticociliate has an active propagation ability by utilizing organic matters obtained from cell strain, bacteria, assorted feed, brain tissue and rotifer tissue. The ciliate achieved population growth activity under the conditions of $5{\sim}45\;ppt$ in salinity and pH 6-9. The ciliate had survived and propagated under the water temperature ranging $10{\sim}30^{\circ}C$, but active growth was observed in the temperature ranges of $10{\sim}25^{\circ}C$. Therapeutic trials were performed with formalin and hydrogen peroxide. The extermination time of the parasites with formalin was in 30 minutes both at 300 and 400 ppm, 60 minutes at 200 ppm, 90 minutes at 100 ppm, and 120 minutes at 50 ppm, respectively. In hydrogen peroxide treatments extermination time was 60 minutes in 300 ppm, 90 minutes in 200 ppm, and 150 minutes at 150 ppm and 100 ppm concentrations.

• Journal of Microbiology and Biotechnology
• /
• v.21 no.5
• /
• pp.519-524
• /
• 2011

The correlation between alcoholic fermentation rate, measured as carbon dioxide ($CO_2$) evolution, and the rate of hydrogen sulfide ($H_2S$) formation during wine production was investigated. Both rates and the resulting concentration peaks in fermentor headspace $H_2S$ were directly impacted by yeast assimilable nitrogenous compounds in the grape juice. A series of model fermentations was conducted in temperature-controlled and stirred fermentors using a complex model juice with defined concentrations of ammonium ions and/or amino acids. The fermentation rate was measured indirectly by noting the weight loss of the fermentor; $H_2S$ was quantitatively trapped in realtime using a pre-calibrated $H_2S$ detection tube which was inserted into a fermentor gas relief port. Evolution rates for $CO_2$ and $H_2S$ as well as the relative ratios between them were calculated. These fermentations confirmed that total sulfide formation was strongly yeast strain-dependent, and high concentrations of yeast assimilable nitrogen did not necessarily protect against elevated $H_2S$ formation. High initial concentrations of ammonium ions via addition of diammonium phosphate (DAP) caused a higher evolution of $H_2S$ when compared with a non-supplemented but nondeficient juice. It was observed that the excess availability of a certain yeast assimilable amino acid, arginine, could result in a more sustained $CO_2$ production rate throughout the wine fermentation. The contribution of yeast assimilable amino acids from conventional commercial yeast foods to lowering of the $H_2S$ formation was marginal.

• Journal of the Korean Society for Nondestructive Testing
• /
• v.19 no.1
• /
• pp.16-24
• /
• 1999

Residual stress is one of the causes which make defects in engineering components and materials. And interest in the measurement of residual stress exists in many industries. There are commonly used methods by which residual stresses are currently measured. But these methods have a little demerits. time consumption and other problems. Therefore we devised a new experimental technique to measure residual stress in materials with a combination of laser speckle pattern interferometry, finite element method and spot heating. The speckle pattern interferometer measures in-plane deformations while the heating provides for very localized stress relief. FEM is used for determining heat temperature and other parameters. The residual stresses are determined by the amount of strain that is measured subsequent to the heating and cool-down of the region being interrogated. A simple model is presented to provide a description of the method. In this paper, the ambiguity problem for the fringe patterns has solved by a phase shifting method.

• Journal of Korean Association for Spatial Structures
• /
• v.7 no.1 s.23
• /
• pp.71-78
• /
• 2007

Stainless steel is very famous for using of industrials structure and joint elements. Stainless steel wire drawing is one of the most ancient crafts. But there's not any standard size of tapered die during tile drawing. This paper was studied die angle and dimension of whole die by using AFDEX drawing simulator. Stress, metal flow and strain rate was analyzed by AFDEX tools during the wire drawing. So optimum data of during dies was taken from them. Simulation data was correspond with experimental data. The results of the optimum dies are shown that (1) Reduction angle is $13.8^{\circ}$ (2) Bark relief angle is $20^{\circ}$ (3) Bearing length is 0.7975mm (4) Bearing dia is 0.2393mm The research of the optimum result when the make dies is connected an enterprise. After researching, I hope that indirection effect creation make development situation of the manufactural technical, practical application of the other die size by the detail data, utility factor and economical efficiency.

• Parasites, Hosts and Diseases
• /
• v.46 no.3
• /
• pp.153-156
• /
• 2008

One of the most common drugs used against a wide variety of anaerobic protozoan parasites is metronidazole. However, this drug is mutagenic for bacteria and is a potent carcinogen for rodents. Thymus vulgaris is used for cough suppression and relief of dyspepsia. Also it has antibacterial and antifungal properties. The aim of this study was to investigate antiamebic effect of Thymus vulgaris against Entamoeba histolytica in comparison with metronidazole. One hundred gram air-dried T. vulgaris plant was obtained and macerated at $25^{\circ}C$ for 14 days using n-hexane and a mixture of ethanol and water. For essential oil isolation T. vulgaris was subjected to hydrodistillation using a clevenger-type apparatus for 3 hr. E. histolytica, HM-1: IMSS strain was used in all experiments. It was found that the minimal inhibitory concentration (MIC) for T. vulgaris hydroalcoholic, hexanic extracts, and the essential oil after 24 hr was 4 mg/mL, 4 mg/mL, and 0.7 mg/mL, respectively. After 48 hr the MIC for T. vulgaris hydroalcoholic and hexanic extracts was 3 and 3 mg/mL, respectively. Therefore, it can be concluded that the Iranian T. vulgaris is effective against the trophozoites of E. histolytica.

• Journal of the Korean Society of Marine Environment & Safety
• /
• v.24 no.4
• /
• pp.482-488
• /
• 2018

Generally, after stern tube bearing shows a significant increase in local load due to propeller load, which increases the potential adverse effects of bearing failure. To prevent this, research on regarding shaft alignment has been carried out with a focus on reducing the relative slope between the shaft and support bearing(s) under quasi-static conditions. However, for a more detailed evaluation of a shafting system, it is necessary to consider dynamic conditions. In this context, the results revealed that eccentric propeller force under transient conditions such as a rapid rudder turn at NCR, lead to fluid-induced instability and imbalanced vibration in the stern tube. In addition, compared with NCR condition, it has been confirmed that eccentric propeller forces given a rapid rudder starboard turn can lift a shaft from the stern tube bearing in the stern tube, contributes to load relief for the stern tube bearing.

• Journal of the Korean Geotechnical Society
• /
• v.25 no.1
• /
• pp.21-29
• /
• 2009

On plane strain condition, many researchers have investigated the earth pressure according to the shape of wall, and standardized method has been applied to the design of the retaining wall. But on cylindrical diaphragm wall, at-rest earth pressure has been generally used. Even though this method is on conservative side, it may lead to over-design. In this paper, the application of convergence confinement method to the calculation of the earth pressure acting on the cylindrical diaphragm wall of a shaft was suggested. In addition, a model test was carried out to investigate the distributions of earth pressure. Model test results show that the earth pressures of diaphragm wall are about 1.4 times larger than active earth pressure and about 0.8 times less than at-rest earth pressure.

• Journal of the Korean Society of Marine Environment & Safety
• /
• v.27 no.7
• /
• pp.1082-1087
• /
• 2021

The propeller shaft has different pattern of behaviors at each static, dynamic, and transient condition to a ship shaft system due to the effects of propeller weight and eccentric thrust, which increases the potential risk of bearing failure by causing local load variations. To prevent this, the various research of the shafting system has been conducted with the emphasis on optimizing the relative slope and oil film retention between propeller shaft and stern tube bearing at quasi-static condition, mainly with respect to the Rules for the Classification of Steel Ships. However, to guarantee a stability of the shafting system, it is necessary to consider the dynamic condition including the transient state due to the sudden change in the stern wakefield during rudder turn. In this context, this study cross-validated the ef ect of propeller shaft behavior on the stern tube bearing during port turn operation, which is a typical transient condition, by using the strain gauge method and displacement sensor for 50,000 DWT medium class tanker. And it was confirmed that the propeller eccentric thrust change showing relief the load of the stern tube bearing.

• Economic and Environmental Geology
• /
• v.43 no.5
• /
• pp.429-441
• /
• 2010

The Sunrise Dam gold deposit is located approximately 850 km ENE of Perth, in the eastern part of the Yilgam Craton, Western Australia. The mine has produced approximately 153 t of Au at an average grade of 4.2 g/t, which stands for the most significant gold discoveries during the last decade in Western Australia. The deposit occurs in the Laverton Tectonic Zone corresponding to the corridor of structural complexity in the Laverton greenstone belt, and characterized by tight folding and thrusting. The mine stratigraphy consists of a complexly deformed and altered volcaniclastic and volcanic rocks. These have been overlain by a turbidite sequence containing generally well-sorted siltstones, sandstones and magnetite-rich shales, which are consistently fining upwards. These sequences have been intruded by quartz diorite, ultramafic dikes, and rhyodacite porphyry (Archean), and lamprophyre dikes (Palaeoproterozoic). These rocks constitute the asymmetric NNE-trending Spartan anticline with north-plunging thrust duplication of the BIF unit. The deposit is located on the western limb of this structure. Transported, fluvial-lacustrine and aeolean sediments lie unconformably over the deposit showing significant variation in relief. Gold mineralization occurs intermittently along a NE-trending corridor of ca. 4.5 km length. The 20 currently defined orebodies are centered on a series of parallel, gently-dipping ($\sim30^{\circ}$) and NESW trending shear zones with a thrust-duplex architecture and high-strain characteristics. The paragenetic sequence of the Sunrise Dam deposit can be divided into five hydrothermal stages ($D_1$, $D_2$, $D_3$, $D_4a$, $D_4b$), which are supported by distinctive features of the mineralogical assemblages. Among them, the D4a stage is the dominant episode of Au deposition, followed by the $D_4b$ stage, which is characterized by more diverse ore mineralogy including base metal sulfides, sulfosalts, and telluride minerals. The $D_4a$ stage contains higher proportions of microscopic free gold (48%) than D4b stage (12%), and pyrite is the principal host for native gold (electrum) followed by tetrahedrite-group minerals in both stages.