• Radiation Oncology Journal
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• v.24 no.2
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• pp.138-143
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• 2006

Purpose: To analyze the long-term stability of Farmer-type cylindrical ionization chambers by calibration factor provided from the KFDA (Korea Food Drug Administration) Materials and Methods: The cylindrical ionization chambers used in this study were the PTW 30001 (30006), 30013, 30002, 30004, 23333, the Capintec PR06C, the WE 2571, the Exradin A12 and the Wellhofer FC65G (IC70). We were analyzed that the $N_k$ and $N_{D.W}$ calibration factor for the cylindrical chambers and compared between the measured $N_{D.W}$ and calculated $N_{D.W}$ calibration factor. Results: We have observed that the long-term stability of the PTW 30013 (30006), the Wellhofer FC65G (IC70) and the NE 2571 has varied within 0.2%. The measured $N_{D,W}$ calibration factor was about 1.0% higher than the calculated $N_{D,W}$ that determined by the $N_k$ calibration factor. Conclusion: The study has evaluated that the long-term stability of the cylindrical chambers through analysis for the $N_k\;and\;N_{D,W}$ calibration factor. It has contributed to the improvement of clinical electron dosimetry in radiotherapy centers.

• Proceedings of the KIEE Conference
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• 2003.10a
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• pp.134-136
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• 2003

In this work, we have seen the effect of hole-transporting layer in organic light-emitting diodes using N,N'-biphenyl-N,N'-bis-(3-methylphenyl)-[1,1'-biphenyl]-4,4'-diamine(TPD) and N,N'-biphenyl-N,N'-bis-(1-naphenyl)-[l,l'-biphenyl]-4,4'-diamine(NPB). NPB is regarded as a better hole trans porting material than TPD, since it has a higher glass transition temperature($T_g$). And current-voltage, luminance-voltage and external quantum efficiency of device were measured with the thickness variation of buffer layer using copper phathalocyanine(CuPc) am polytetrafluoroethylene (PTEE) at room temperature. We have obtained an improvement of External quantum efficiency when the CuPc 30[nm] and PTFE 1.0[nm] is used.

• Korean Journal of Mathematics
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• v.28 no.4
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• pp.907-913
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• 2020

Let R be a commutative ring with identity and let M be a w-module over R. Denote by ℱM the set of all w-submodules of M such that (M/N)w is w-cofinitely generated. Then it is shown that M is w-Artinian if and only if ℱM is closed under arbitrary intersections, if and only if ℱM satisfies the descending chain condition.

• Journal of the Korea Organic Resources Recycling Association
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• v.14 no.2
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• pp.63-70
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• 2006

The purpose of this study was to develop the stability index of landfill sites to assess it's degree of stability. In order to develop the stability index, field data including leachate qualities, Landfill gas (LFG) composition and element composition of wastes from 50 closed landfills were collected. Three parameters-BOD/CODcr among leachate quality parameters, $CH_4$ among landfill gases, and C/N ratio from wastes-were found to be the best parameters for measuring the stability of landfill sites. The trend line of these parameters were used to Also, $CH_4$ from landfill gases and C/N ratio from wastes were found to be the best parameters. The trend lines of these parameters were used to develop the stability index of landfill sites. The equation for the index was as following; $I_{LS}=S_L+S_G+S_W$ $S_L=-\{4.892+16.587{\cdot}ln[BOD/COD_{Cr]\}$ $S_G=53.872-12.782{\cdot}ln[CH_4]$ $S_W=79.382-20.013{\cdot}ln[C/N]$ (The maximum score for $S_L$, $S_G$, and $S_W$ was 33.3.) where, $I_{LS}$ : The stability index of the landfill $S_L$ : The stability score of the leachate $S_G$ : The stability score of the landfill gas $S_W$ : The stability score of the waste.

• Applied Chemistry for Engineering
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• v.22 no.4
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• pp.416-422
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• 2011

In this study, the effect of cosurfactant on the phase equilibrium and dynamic behavior was studied in systems containing NP7 nonionic surfactant solutions and nonpolar hydrocarbon oils. All cosurfactants used during this study such as n-pentanol, n-octanol and n-decanol acted as a hydrophobic additive and thus promoted the transition from an oil in water (O/W) microemulsion (${\mu}E$) in equilibrium with an excess oil phase to a three-phase region containing excess water, excess oil, and a middle-phase microemulsion and further to a water in oil (W/O) ${\mu}E$ in equilibrium with the excess water phase. The transition temperature was found to decrease with both increases in the chain length and amount of addition of a cosurfactant. Dynamic behavior studies under O/W ${\mu}E$ conditions showed that an oil drop size decreased with time due to the solubilization into micelles. On the other hand, both the spontaneous emulsification of water into the oil phase and the expansion of oil drop were observed under W/O ${\mu}E$ conditions because of the diffusion of surfactant and water into the oil phase. Under conditions of a three-phase region including a middle-phase ${\mu}E$, both the rapid solubilization and emulsification of the oil into aqueous solutions were found mainly due to the existence of ultra-low interfacial tension. Dynamic interfacial tension measurements have been found to be in a good agreement with dynamic behavior results.

• Journal of the Korean Vacuum Society
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• v.14 no.2
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• pp.84-90
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• 2005

The influence of plasma parameters on the growth of $In_{0.2}Ga_{0.8}N/GaN$ heterostructures has been investigated using plasma-assisted molecular beam epitaxy. Since plasma ejects plenty of energetic particles with different energy levels and flux density at various rf power levels, plasma modulated both growth rate and optical properties significantly. For instance, surface roughness and the emission spectrum of photoluminescence were degraded at low and high rf power. According to sharp interfaces between epitaxial films and strong peaks observed from photoluminescence spectra, our experimental setup presented optimal operation range of rf powers at around 400W. The phenomena could be explained by the presence of energetic particles modulating the rate of plasma stimulated desorption and surface diffusion, and energetic particles exceeding critical value resulted in the incorporation of defects at subsurface. The optimal rf power regime increased by 100W for $In_{0.2}Ga_{0.8}N/GaN$ growth in comparison with GaN. The effects of rf power were discussed in conjunction with kinetic processes being stimulated by energetic particles.

• Asian-Australasian Journal of Animal Sciences
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• v.5 no.4
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• pp.653-658
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• 1992

Crossbred dairy does were fed a roughage diet (IVOMD 56%, N 2.27%) ad libitum, and supplemented with urea-molasses (3% W : W) (UM) at levels on an air dry basis of 1.5% or 3% of liveweight or an iso-energetic, iso-nitrogenous mixture of cottonseed meal and molasses (25 : 75 w : w) (CM). Eight does, four lower-producers and four higher-producers (1.9 and 2.5 kg/day respectively in week 7 of lactation) arranged in two Latin Squares, received each of the four diets for three weeks. Dry matter, digestible organic matter and N intakes were higher for high-producers and high levels of supplement but did not differ between nitrogen sources. Milk production was higher by high-producers; interactions were significant between level of supplement and production group and between level of supplement and N-source, with maximum production by high producers on high levels of CM. The main effects of level of supplement were only significant for production or composition. and total solids; N-source did not have significant effects on liveweight, milk production or composition. We conclude that does of moderate capacity for milk production, receiving a diet of two-thirds moderate quality roughage, one third urea-molasses, will not respond to increased level of supplementation or to replacement of urea with cottonseed meal.

• Journal of Nutrition and Health
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• v.30 no.9
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• pp.1067-1072
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• 1997

One known effect of long chain n-3 polyunsaturated fatty acids is their ability to decrease plasma triglycerides. However, identification of the specific n-3 fatty acids and the underlying mechanisms responsible for this change remains uncertain. This present study was designed to evaluate the effects of moderate levels of dietary docosahexaenoic acid (22 :6(n-3)) on modulating plasma triglyderides. Male CD-1 mice were maintained for 15 days on identical diets containing either docosahexahexaenoic acid ethyl ester(1.5%, w/w) or linoleic acid(18 : 2(n-6)) ethyl ester (1.5%, w/w) . Plasma triglycerides were 40% lower in the docosahexaenoic acid group than in the linoleic acid group. Hepatic carnitine palmitoyltransferase activity (a key regulatory enzyme for mitocondria $\beta$-oxidation) was not significantly different between the dietary groups. However, plasma acid soluble acylcarnitine levels (which increase with increasing $\beta$-oxidation )were significantly higher in the decosahexaenoic acid group. This data suggests that plasma triglyceride levels are lower in mice fed diets containing moderate levels of docosahexaenoic acid compared to linoleic acid, but this effect on plasma triglycerides is not modulated through an augmentation of mitochondrial $\beta$-oxidation.

• The KIPS Transactions:PartC
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• v.13C no.2 s.105
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• pp.167-170
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• 2006

Most wavelength assignment algorithms assume that every node has infinite ADMs and I/O blocking is excluded. Furthermore wavelengths continue to occur intermittently in the network using existing algorithms. This can result in increased link blocking under dynamic traffic circumstances. In audition, it can create time-complexity problems such as O(W $N^3$) in the worst case scenario. In this paper, we propose a new wavelength assignment algorithm which has time-complexity of O(W $N^2$) and considers both I/O and link blocking. The basic idea is to maximize the number of links where wavelengths will be assigned continuously after present assignment. As a result, the number of intermittent wavelengths is minimized, and blocking probabilities are decreased.

• Journal of the Korean Magnetics Society
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• v.15 no.2
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• pp.130-132
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• 2005

Tungsten carbon nitride (W-C-N) thin films were produced by reactive radio frequency (RF) magnetron sputter-ing of tungsten in $Ar-N_2$ gas mixture. The effects of the variation of nitrogen partial pressure on the composition, and structural properties of these films as well as the influence of post-deposition annealing have been studied. When $La_{0.67}Sr_{0.33}MnO_3$ was coated on the W-C-N/Si substrate, coercivity ($H_c$) and magnetization at room temperature shows 58.73 Oe, and 29.4 emu/cc, respectively. In order to improve the diffusion barrier characteristics, we have studied the impurity behaviors to control the ratios of nitrogen and carbon concentrations.