• Journal of the Institute of Electronics Engineers of Korea SD
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• v.41 no.8
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• pp.17-24
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• 2004

Quantum effects in the poly-gate are analyzed in two dimensions using the density-gradient method, and their impact on the short-channel effect of double-gate MOSFETs is investigated. The 2-D effects of quantum mechanical depletion at the gate to sidewall oxide is identified as the cause of large charge-dipole formation at the corner of the gate. The bias dependence of the charge dipole shows that the magnitude of the dipole peak-value increases in the subthreshold region and there is a large difference in carrier and potential distribution compared to the classical solution. Using evanescent-nude analysis, it is found that the quantum effect in the poly-gate substantially increases the short-channel effect and it is more significant than the quantum effect in the Si film. The penetration of potential contours into the poly-gate due to the dipole formation at the drain side of the gate corner is identified as the reason for the substantial increase in short-channel effects.

• Korean Journal of Food Science and Technology
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• v.19 no.5
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• pp.441-445
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• 1987

The subcellular distribution of lipoxygenase in germinating soybean seeds (Glycine max[L.] AmSoy) was investigated by using differential centrifugation and sucrose density gradient fractionation. Most of lipoxygenase -1 and -2/3 activities was present in the supernatant fraction after differential centrifugation of homogenates prepared from three-day-old seedlings; only 1.5% of lipoxygenase activity remained in particulate fractions. The results of a sucrose density gradient fractionation (three-day-old) showed that the lipoxygenase activity coincided with acid phosphatase at the densities of 1.19, 1.23, $1.25g/cm^3$, even though most of lipoxygenase and acid phosphatase activities appeared in supernatant fractions. There was no indication that mitochondria contained any lipoxygenase activity, and it does not appear that glyoxysomes and ER contained any lipoxygenase activity either.

• Proceedings of the KOSOMBE Conference
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• v.1993 no.11
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• pp.128-131
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• 1993

In order to get the basic data for the study of the heat stimulation of burning moxa, the pattern of combustion temperature, which is one of the important factors of thermal characteristics, was measured by density of cone moxa along the time procedure. The following results have been obtained 1) The pattern of combustion temperature by moxa burning was classified into input period which means the infiltration of heat into the area and output period which means the radiation of heat from the area. The input period consists of preheating and heating periods, while the output period consists of heat retaining and cooling periods. 2) The pattern of combustion temperature showed the same type or curve, which was not influenced by the moxa weight. However, Its pattern gradient are varied by density. It is considered that the pattern of combution temperature is primarily influenced by the rate of combustion temperature, gradient temperature and duration of combustion.

• Advances in nano research
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• v.17 no.3
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• pp.197-211
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• 2024

This work investigates the thermo-mechanical vibration frequencies of an embedded composite nano-beam restrained with elastic springs at both ends. Composite nanobeam consists of a matrix and short fibers as reinforcement elements placed inside the matrix. An approach based on Fourier sine series and Stokes' transform is adopted to present a general solution that can examine the elastic boundary conditions of the short-fiber-reinforced nanobeam considered with the Halpin-Tsai model. In addition to the elastic medium effect considered by the Winkler model, the size effect is also considered on the basis of nonlocal strain gradient theory. After creating an eigenvalue problem that includes all the mentioned parameters, this problem is solved to examine the effects of fiber and matrix properties, size parameters, Winkler stiffness and temperature change. The numerical results obtained at the end of the study show that increasing the rigidity of the Winkler foundation, the ratio of fiber length to diameter and the ratio of fiber Young's modulus to matrix Young's modulus increase the frequencies. However, thermal loads acting in the positive direction and an increase in the ratio of fiber mass density to matrix mass density lead to a decrease in frequencies. In this study, it is clear from the eigenvalue solution calculating the frequencies of thermally loaded embbeded short-fiber-reinforced nanobeams that changing the stiffness of the deformable springs provides frequency control while keeping the other properties of the nanobeam constant.

• Journal of the Korean Wood Science and Technology
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• v.52 no.3
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• pp.234-242
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• 2024

In this study, the effect of carbonization temperature and mixing ratio of ceramics manufactured from sawdust, chaff and charcoal on sound absorption performance and density profile was investigated. The density profile of ceramics prepared by the addition rates of sawdust, chaff and charcoal showed the highest value at 91.00% when the ratio of sawdust, chaff and charcoal was 50:25:15. However, the difference in density profile according to the addition rate was insignificant. The density profile of ceramics manufactured according to the carbonization temperature showed the highest value of 88.06% when manufactured at 800℃. However, it does not show any particular trend, so it is understood that the effect of the carbonization temperature on the density gradient is small. On the other hand, the sound absorption coefficients of ceramics prepared by the addition rates of sawdust, chaff and charcoal is between 0.3 and 0.4 at almost all frequencies when the addition rates of sawdust, chaff and charcoal are 50:30:10 and 50:35:5, respectively. Therefore, as the chaff particles increased, the sound absorption performance was improved. In addition, the sound absorption coefficients of the ceramics manufactured at each carbonization temperature showed the highest value in the ceramics manufactured at 1,200℃.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.18 no.1
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• pp.213-225
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• 1988

This study was to compare the quality of image by different screen and film combinations. Using the sensitometer measured the speed and average gradient of blue sensitive films and orthochromatic films. The films was combined with rare earth screen LR, LM, LF and conventional screen OM, OH, XOR, OKa and exposed the step wedge to impulse 2, 3, 4, 6, 10, 15, 24,3 8, 60 and measured the density. The following results were obtained: 1. The density of film and film-screen combinations showed significant difference, then in film-screen combinations was significantly different by the screens than films. 2. The speed of blue sensitive films was little different, the TMG of orthochromatic films produced high speed, and the AX film was high average gradient. 3. The relative speed of film-screen combinations showed significant difference, and was high in the OKa of the conventional screens and in the LR of the rare earth screens, especially that of LR screen in the combination with blue sensitive films was high. 4. The average gradient of film-screen combinations showed no significant difference, and was high in the OKa screen and LR/OG combination, and that of OKa/AX combination was highest. 5. The latitude of film-screen combinations showed significant difference by screens, and was high in the LM screen in combination with blue sensitive films and in the OM screen in combination with orthochromatic films. 6. The subject contrast of film-screen combinations showed significant difference by screen, and was high in the LR screen in combination with blue sensitive AX film and orthochromatic TMG film.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.31 no.3 s.258
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• pp.209-216
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• 2007

Bacterial chemotaxis is essential to the study of structure and function of bacteria. Although many studies have accumulated the knowledge about chemotaxis in the past, the motion of a single bacterium has not been studied much yet. In this study, we have developed a device microfabricated by soft lithography and consisting of microfluidic channels. The microfluidic assay generates a concentration gradient of chemoattractant linearly in the main channel by only diffusion of the chemicals. Bacteria are injected into the main channel in a single row by hydrodynamic focusing technique. We measured the velocity of bacteria in response to a given concentration gradient of chemoattractant using the microfludic assay, optical systems with CCD camera and simple PTV (Particle Tracking Velocimetry) algorithm. The advantage of this assay and experiment is to measure the velocity of a single bacterium and to quantify the degree of chemotaxis by statistically analyzing the velocity at the same time. Specifically, we measured and analyzed the motility of Escherichia coli strain RP437 in response to various concentration gradients of L-aspartate statistically and quantitatively by using this microfluidic assay. We obtained the probability density of the velocity while RP437 cells are swimming and tumbling in the presence of the linear concentration gradient of L-aspartate, and quantified the degree of chemotaxis by analyzing the probability density.

• Journal of the Korea Computer Graphics Society
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• v.30 no.3
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• pp.141-147
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• 2024

Progressive photon mapping is a widely adopted rendering technique that conducts a kernel-density estimation on photons progressively generated from lights. Its hyperparameter, which controls the reduction rate of the density estimation, highly affects the quality of its rendering image due to the bias-variance tradeoff of pixel estimates in photon-mapped results. We can minimize the errors of rendered pixel estimates in progressive photon mapping by estimating the optimal parameters based on gradient-based optimization techniques. To this end, we derived the gradients of pixel estimates with respect to the parameters when performing progressive photon mapping and compared our estimated gradients with finite differences to verify estimated gradients. The gradient estimated in this paper can be applied in an online learning algorithm that simultaneously performs progressive photon mapping and parameter optimization in future work.

• Journal of the Korean Wood Science and Technology
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• v.39 no.4
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• pp.344-350
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• 2011

In this study, LVLs of radiata pine were fabricated with non-preservative treated veneers, CuAz treated veneers, and ACQ treated veneers, using aqueous vinyl urethane adhesive and phenol modified resorcinol resin adhesive. Then density gradient, bonding strength, bending properties and decay resistance of LVLs were evaluated. As results, the cone-shaped and higher density gradient pattern was found in layer close to glueline. After cyclic water boiled test, the LVL bonded with aqueous vinyl urethane resin adhesive was delaminated in all layers or partly delaminated including check, chasm in glueline layer. In the case of LVL bonded with phenol modified resorcinol resin adhesive, despite slight cupping due to great glueline stress and vertical check between glueline layers, it was observed that the bonding strength to delamination was higher, owing to most absence of delamination through overall glueline. On the other hand, in the decay test, mass loss by brown rot fungi was greater than white rot fungi in LVL bonded with aqueous vinyl urethane resin adhesive. However, in LVL bonded with phenol modified resorcinol resin adhesive, the mass loss by brown rot fungi was slight and non-preservative treated LVL was low. The mass loss of preservative-treated LVL was 0 (zero), showing the high decay resistance effect.

• Journal of Korean Society of Water and Wastewater
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• v.30 no.5
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• pp.553-559
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• 2016

There has been increasing global interest in the environmental pollution problems produced by fossil fuel consumption and greenhouse gas emissions. In order to tackle these issues, new renewable energy such as solar, wind, bio gas, fuel cell and pressure retarded osmosis(PRO) have been developed extensively. Among these energy sources, PRO is one of the salinity gradient power generation methods. In PRO, energy is obtained by the osmotic pressure generated from the concentration difference between high and low concentration solutions separated by a semipermeable membrane. The development for high power density PRO membranes is imperative with the purpose of commercialization. This study investigates development of thin film composite PRO membrane and spiral wound module for high power density. Also, the influence of membrane backing layer on power density was identified, and the characteristic factors of PRO membranes was determined. Different backing layers were used to improve power density. As expected, the PRO membrane with more porous backing layer showed higher power density.