• Journal of the Korean Institute of Telematics and Electronics D
• /
• v.34D no.7
• /
• pp.37-44
• /
• 1997

A dadaptive refinement tetrahedron mesh has been presented for using in full band GaAs monte carlo simulation. A uniform tetrahedron mesh is used without regard to energy values and energy variety in case of the past full band simulation. For the uniform tetrahedron mesh, a fine tetrahedron is demanded for keeping up accuracy of calculation in the low energy region such as .GAMMA.-valley, but calculation time is vast due to usin gthe same tetrahedron in the high energy region. The mesh of this study, thererfore, is consisted of the fine mesh in the low energy and large variable energy region and rough mesh n the high energy. The density of states (DOS) calculated with this mesh is compared with the one of the uniform mesh. The DOS of this mesh is improved th efive times or so in root mean square error and the ten times in the correlation coefficient than the one of a uniform mesh. This refinement mesh, therefore, can be used a sthe basic mesh for the full band GaAs monte carlo simulation.

• Water for future
• /
• v.10 no.1
• /
• pp.101-117
• /
• 1977

The statatistical characteristics and spectra of sea waves at Mookho were analysed by several statistical methods. As the results, the following conclusions are obtained: 1. Values of surface elevation of sea wave are better fitted to Gram Charlier distribution than Gaussian distribution. This proves that sea waves have not only characters of irregularity but also non-linearity. 2. Distribution of maxima of surface elevation practically follows the distribution of Cartwright and Longuet-Higgins, also spectral width parameter is found to be increased with the increase of root mean square of surface elevation. 3. Sea wave may have spectrum of broad frequency band, however distributions of wave heights and periods follow the Rayleigh distribution which is derived from the assumption of narrow frequency band. 4. Ratios among mean wave heights from observed data show good agreements with theoretical values from Rayleigh distribution. 5. Spectral density and spectral width parameter increase with increase of wind velocity. And wave period at optimum band gas higher value than significant wave period by about 10 percent.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2002.05a
• /
• pp.153-159
• /
• 2002

This paper deals with the measurement of the fluid viscosity by using the torsional vibration of a circular red excited by a torsional vibrator at one end. The effect of an adjacent viscous fluid on the torsional vibration of the rod has been studied theoretically and expressed in terms of the mechanical impedance. The theoretically-obtained trend that the mechanical impedance is proportional to the square root of the viscosity times the density of the fluid has been confirmed by the impedance measurement. The paper demonstrates that a torsionally-vibrating rod can be used as a sensor to measure the viscosity of a fluid.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
• /
• v.14 no.1
• /
• pp.169-172
• /
• 1984

The author observed a cystic lesion which had new radiographic entities in the 6 years old male patient and obtained the following features. 1. The main clinical feature is the swelling. 2. The lesion is situated on the buccal surface of a erupting mandibular first molar. 3. The affected molar is tilted, so that the apices are adjacent to the lingual plate of the mandible. 4. The affected molar is of normal morphology, caries-free and vital. 5. The radiographic feature is the cystic radiolucency which is extended over the buccal surface of the roots of the affected molar and slightly inferior to the root apices. 6. The dental papilla of the affected molar shows the lamina dura of relatively normal density and definitition. 7. The buccal surface shows the laminated new bone formation. 8. The inferior concave border of the lesion is delineated by a thick and calcified layer of cortical bone. 9. The lesion causes displacement of the developing second molar of which anterior cortex is partially destroyed.

• Food Science and Preservation
• /
• v.7 no.1
• /
• pp.8-11
• /
• 2000

The antimicrobial extracts of rheum palmatum and coptis chinensis root as well as grapefruit seed extract(GFSE) were applied to dipping treatment for keeping qualities of cucumbers, respectively, which were then packed in low density polyethylene(LDPE) films incorporated with 1 % antimicrobial extracts and stored $10^{\circ}C$. Dipping and packaging in the antimicrobial agents suppressed the growth of putrefactive microorgani는 and the decay ratio of cucumbers. In addition, the loss ratio of ascortic acid content and their weight was decreased during the sotrage of cucumbers. Consequently, the combined method of dippinf and packaging in antimicrobial agents turned out to be superior to dipping treatment or film-packaging in the view point of decay ratio and the keeping qualities of cucumbers.

• The Transactions of the Korean Institute of Electrical Engineers
• /
• v.35 no.8
• /
• pp.316-322
• /
• 1986

In this paper, the photodoping effect on the interface of Ag-amorphous As2S3 thin film has been investigated by measuring the resistance change of the Ag layer, the absorption coefficient of the As2S3, the optical density of As2S3 layer and the short-circuit photocurrents under light irradiation. As the experimental results, the photodissolution rate and the photodiffusion rate depends on the magnitude of photon energy absorbed in the As2S3. The sensitivity limit of the photodissolution rate at Ag layer was about 630[nm] and the sensitivity limit of the photodiffusion rate at the Ag-As2S3 interface was about 680[nm]. Also, it was found that the depth of photodiffusion was proportional to the square root of exposing time.

• Structural Engineering and Mechanics
• /
• v.12 no.4
• /
• pp.409-428
• /
• 2001

The characteristics of dynamic wheel loads of heavy vehicles running on bridge and rigid surface are investigated by using three-dimensional analytical model. The simulated dynamic wheel loads of vehicles are compared with the experimental results carried out by Road-Vehicles Research Institute of Netherlands Organization for Applied Scientific Research (TNO) to verify the validity of the analytical model. Also another comparison of the analytical result with the experimental one for Umeda Entrance Bridge of Hanshin Expressway in Osaka, Japan, is presented in this study. The agreement between the analytical and experimental results is satisfactory and encouraging the use of the analytical model in practice. Parametric study shows that the dynamic increment factor (DIF) of the bridge and RMS values of dynamic wheel loads are fluctuated according to vehicle speeds and vehicle types as well as roadway roughness conditions. Moreover, there exist strong dominant frequency resemblance between bounce motion of vehicle and bridge response as well as those relations between RMS values of dynamic wheel loads and dynamic increment factor (DIF) of bridges.

• Proceedings of the KSME Conference
• /
• 2001.06b
• /
• pp.378-385
• /
• 2001

This paper deals with the effect of an adjacent viscous fluid on the torsional vibration of a circular rod excited by a transducer at one end. The interaction between the torsional vibration of the rod and the fluid has been studied theoretically and expressed in terms of the mechanical impedance. The theoretically-obtained trend that the mechanical impedance is proportional to the square root of the viscosity times density of the fluid has been confirmed by the impedance measurement. The paper demonstrates that a torsionally-vibrating rod can be used as a sensor measuring the viscosity of a fluid.

• Korean Journal of Organic Agriculture
• /
• v.19 no.spc
• /
• pp.135-138
• /
• 2011

In traditional organic rice culture practices, control of weeds is a big problem. This study was conducted to increase the rice production. Results showed that Plant height, SPAD, root length and weight were higher in pot raised seedling than broadcasting method except number of panicles. High plant density caused reduction in plant height, number of culm and chlorophyll content of the rice. No lodging was observed in both methods. Thickness of third internode and culm length was more in pot raised seedlings at both sites. When organic material was used rice yield increased by 3.81%. Higher rice production (10%) was recorded in the fields planted with pot raised seedlings. From the above study it could be conclude that the pot raised seedlings perform better than the seedlings raised by broadcasting methods.

• Journal of Surface Science and Engineering
• /
• v.22 no.3
• /
• pp.118-127
• /
• 1989

The rate of electrodeposition Zinc-nickel alloy on to electrolytic ione in sulface solution both under an inter and air atmospherss has studied by use of a rotating disc geometry. The kinetics shows 1st order reaction, and the rate constants are proportional to the square root of rpm, however, they are less than the valuse suggested by Levich. The rate constants of zinc deposition approach the total mass transfer rate constants with increasing potential and deviate with increasing rotaing speed, but those of nickel deposition are constant. Below $40^{\circ}C$ the activation engrgies of zinc deposition and nikel deposition were 4.4Kcal/mol and 6.3Kcal/mol respectively. There results show that overall reaction rate of zinc-nickel plaeting is controlled by mixed reaction and zinc deposotion is more affected by mass transfer reaction than nickel. The current density for the zinc-nickel plating was less in an air atmosphere than in a nitrogen atmosphere. The cathode efficiency increased with decreasing cathode rotating speeds, potentials, and increasing temperatures. Zzinc-nickel platings are more improved in microhardnss than zinc platings.