• Journal of Radiation Protection and Research
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• 제34권4호
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• pp.155-164
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• 2009

In this paper, we used computerized glow curve deconvolution (CGCD) software with several models for the simulation of a TL glow curve which was used for analysis. By using the general approximation plus model, parameters values of the glow curve were analyzed and compared with the other models parameters (general approximation, mixed order kinetics, general order kinetics). The LiF:Mg,Cu,Si and the LiF:Mg,Cu,P material were used for the glow curve analysis. And we based on figure of merits (FOM) which was the goodness of the fitting that was monitored through the value between analysis model and TLD materials. The ideal value of FOM is 0 which represents a perfect fit. The main glow peak makes the most effect of radiation dose assessment of TLD materials. The main peak of the LiF:Mg,Cu,Si materials has a intensity rate 80.76% of the whole TL glow intensity, and that of LiF:Mg,Cu,P materials has a intensity rate 68.07% of the whole TL glow intensity. The activation energy of LiF:Mg,Cu,Si was analyzed as 2.39 eV by result of the general approximation plus(GAP) model. In the case of mixed order kinetics (MOK), the activation energy was analyzed as 2.29 eV. The activation energy was analyzed as 2.38 eV by the general order kinetics (GOK) model. In the case of LiF:Mg,Cu,P TLD, the activation energy was analyzed as 2.39 eV by result of the GAP model. In the case of MOK, the activation energy was analyzed as 2.55 eV. The activation energy was analyzed as 2.51 eV by the GOK model. The R value means different ratio of retrapping-recombination. The R value of LiF:Mg,Cu,Si TLD main peak analyzed as $1.12\times10^{-6}$ and $\alpha$ value analyzed as $1.0\times10^{-3}$. The R of LiF:Mg,Cu,P TLD analyzed as $7.91\times10^{-4}$, the $\alpha$ value means different ratio of initial thermally trapped electron density-initial trapped electron density (include thermally disconnected trap electrons density). The $\alpha$ value was analyzed as $9.17\times10^{-1}$ which was the difference from LiF:Mg,Cu,Si TLD. The deep trap electron density of LiF:Mg,Cu,Si was higher than the deep trap electron density of LiF:Mg,Cu,P.

• Journal of Advanced Marine Engineering and Technology
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• 제29권5호
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• pp.495-501
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• 2005

Al is a active metal that owes its resistance to a thin, protective, barrier oxide surface layer, which is stable in air and neutral aqueous solution. Thus Al alloys are widely used in architectural trim. cold & hot-water storage vessels and piping. However Al and most of its alloy may corrode with some forms such as pitting corrosion, intergranular corrosion and galvanic corrosion in the case of exposure to various industrial and marine atmosphere. Therefore a correct evaluation of corrosion resistance for their Al and Al alloys may be more important in a economical point of view. In this study. a relative evaluation of corrosion resistance for three kinds of Al alloys such as ALDC2, ALDC3, and ALDC8 series was carried out with electrochemical method. There is a tendency that corrosion potential is shifted to positive or negative direction by alloying components regardless of corrosion resistance. Moreover the data of corrosion properties obtained from cathodic Polarization curve, cyclic voltammogram and AC. DC impedance respectively showed a good correspondence each other against the corrosion resistance but variation of corrosion potential. passivity current density of anodic polarization curve and corrosion current density by Tafel extrapolation and Stern-Geary method didn't correspond with not only each other but also considerably the data of corrosion properties discussed above. Therefore it is suggested that an optimum electrochemical evaluation for corrosion resistance of Al alloy is to calculate the diffusion limiting current density of cathodic polarization curve, impedance of AC or DC and polarization resistance of cyclic voltammogram.

• 한국경제지리학회지
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• 제16권3호
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• pp.445-457
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• 2013

본 논문의 목적은 우리나라 도시공간구조 변화를 시계열적으로 분석하고, 지역별 규모별 그 특성을 도출하는 것이다. 본 논문에서 도시공간구조는 인구밀도경사함수(population gradient curve)를 통해 분석하였고, 분석의 시간적 범위는 자료구축의 가능성을 고려하여 2000년부터 2010년까지로 설정하였으며, 공간적 범위는 광역시를 제외한 70개 도시이다. 본 논문의 분석결과를 요약하면 다음과 같다. 첫째, 우리나라 도시들은 평균적으로 도심 인구밀도는 감소하고, 인구밀도 경사도는 완만해져 도심 집중현상보다 외곽지역으로의 확산이 활발하게 진행되는 것으로 나타났다. 둘째, 비수도권 지역은 전국 평균과 동일한 형태의 공간구조 변화를 경험하였지만, 수도권 지역은 외곽지역뿐만 아니라 도심까지 인구밀도가 함께 높아지는 현상이 나타났다. 셋째, 인구 20만 이상의 중도시와 대도시에서는 도심 집중현상보다는 도시 외곽지역으로의 확산이 우세하게 나타난 반면, 인구 20만 미만의 소도시에서는 도심 인구밀도가 높아지면서 인구밀도 경사도의 절댓값이 커지는 도심 집중현상, 즉 압축도시의 특성이 나타나는 것으로 분석되었다.

• 전자공학회논문지
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• 제52권4호
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• pp.56-61
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• 2015

고주파에서 이상적인 커패시턴스-전압 곡선과 결함이 존재하여 늘어진 커패시턴스-전압 곡선을 SiGe p-FinFET 시뮬레이션을 이용하여 보였다. 두 곡선이 게이트 전압 축으로 늘어진 전압 차이를 이용하여 평균적인 계면 결함 밀도를 구할 수 있었다. 또한 같은 특성을 이용하는 Terman의 방법으로 에너지에 따른 계면 결함 밀도를 추출하고, 동일한 에너지 구간에서 평균값을 구하였다. 전압 차이로 구한 평균 계면 결함 밀도를 Terman의 방법으로 구한 평균값과 비교하여, 두 방법의 결과가 거의 비슷한 평균 계면 결함 밀도를 나타낸다는 것을 검증하였다.

• 한국세라믹학회지
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• 제16권3호
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• pp.142-154
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• 1979

The effects of microstructures and some additives $(CoO and Al_2O_3$) on the magnetic properties such as initial permeability, $\mu$-T curve, coercive force, and magnetic induction of MnZn ferrites have been studied. The powder was prepared by Hot Petroleum Drying Method. The basic composition of MnZn ferrites was 25.5mole % MnO, 22.0 mole% ZnO, 52.5 mole% $Fe_2O_3$. CoO in a concentration range from 0.05 to 0.5 mole% and $Al_2O_3$ from 2.5 to 7.5 mole% were added. Sintered density increased up to 97.5% of theoretical density. Permeability increased as average grain size increased, and that coercive force decreased as average grian size increased. Magnetic induction increased as sintered density increased. The variation of initial permeability with temperature in a temperature range from 0$^{\circ}$ to $60^{\circ}C$ was lowered (a flatter $\mu-T$ curve) as sintering temperature decreased. The compensation temperature To ofmagnetocrystalline anisotropy constant K1 and initial permeability varied with the species and amount of additives. When 0.05 mole% CoO was added to the basic composition, initial permeability at $15^{\circ}C$ increased from 5200 to 5900. The variation ofinitial permeability with temperature in a temperature range from 0^{\circ}to $60^{\circ}C$ was smaller (a flatter $\mu$-T curve) than that of the basic composition of Mn Zn ferrites. When 2.5 mole% $Al_2O_3$ was added, initial permeability at $15^{\circ}C$ decreased from 5200 to 3000. But the variation of initial permeability with temperature in a temperature range from 0$^{\circ}$to $60^{\circ}C$ was smaller (a flat ter $\mu-T$ curve) than when 0.05 mole% CoO was added. Experimental results showed that the conditions necessary for the occurrence of a very high permeability and a flat $\mu$-T curve were controversial even in a temperature range from $0^{\circ}$to $60^{\circ}C$.

• 한국산림과학회지
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• 제57권1호
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• pp.1-7
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• 1982

원래 인구증가곡선(人口增加曲線)으로 알려진 단순(單純) logistic 곡선(曲線)은 초본식물(草本植物)의 성장표현(成長表現)에도 이용(利用)되어 왔다. 초본(草本)의 경우 이론치(理論値)와 실측치(實測値) 사이의 적합도(適合度)는 만족(滿足)스러운 것으로 알려져 있다. 그러나 초본(草本)과는 특성(特性)이 상이(相異)한 목본식물(木本植物)의 성장(成長)에 단순(單純) logistic 곡선(曲線)이 적용(適用)된 예는 극히 드물다. 따라서 그에 대한 적합성(適合性) 여부는 아직 의문시 되고 있다. 본연구(本硏究)에서는 임분밀도관리(林分密度管理)의 기초(基礎)가 되고 있는 단순(單純) logistic 곡선(曲線)의 적합성(適合性)을 조사하기 위하여 이것을 소나무임분(林分)에 적용(適用)시켜 보았다. 적합성검정(適合性檢定)을 위해서는 Chi-square test가 채용되었다.

• 한국수학사학회지
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• 제13권1호
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• pp.1-14
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• 2000

The first part of this thesis discusses the Pearson's Curve Family which gives $\beta$distribution, $\Gamma$-distribution, $X^2$-distribution and t-distribution. The second part of this thesis gives some brief process of calculations for normal distribution density and t-distribution density by the 7-th type Curve of Pearson's Curve Family. Finally, a conclusion arrives that Student(Gosset) could not find out his famous 'Student's t-distribution' without his attending of 'Pearson's Differential Equation' class taught by Pearson himself when he was a senior student. However, if he had got a professorship at the Pearson Statistics Laboratory, the University of London, then he could not have found 'Student's t-distribution' for small sampling technique of modern statistics.

• 천문학회지
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• 제8권1호
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• pp.3-9
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• 1975

Densities of the three constituent spheroids of the same eccentricity as our earlier model of the Galaxy are assumed to be given by an analytical form of $_{{\rho}i}$(r)=$k_ie^{-m_ir^u{_i}}$, where $k_i,\;m_i$, and ${\alpha}i$ are obtained by comparing with the results of the previous model. Using three values of $_{{\rho}i}$(r) the galactic rotation curve, mass of each spheroid and the whole Galaxy are calculated, and the three dimensional density distribution in the Galaxy is also obtained. The calculated rotation curve of the model Galaxy is in good agreement with the observed curve, and the shape of the cross section of the model Galaxy given by the computed density is very similar to the inferred shape of the spiral galaxies.

• Journal of Forest and Environmental Science
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• 제36권1호
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• pp.37-46
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• 2020

Vegetation carbon sequestration and regeneration are the two major parameters of forest research. In this study, we analyzed the vegetation carbon stock and regeneration of community-managed pine plantation of Kathmandu, central Nepal. Vegetation data were collected from 40 circular plots of 10 m radius (for the tree) and 1m radius (for seedling) applying a stratified random sampling and nested quadrat method. The carbon stock was estimated by Chave allometric model and estimated carbon stock was converted into CO₂ equivalents. Density-diameter (d-d) curve was also prepared to check the regeneration status and stability of the plantation. A d-d curve indicates the good regeneration status of the forest with a stable population in each size class. Diversity of trees was very low, only two tree species Pinus roxburghii and Eucalyptus citriodora occurred in the sample plots. Pine was the dominant tree in terms of density, basal area, biomass, carbon stock and CO₂ stock than the eucalyptus. The basal area, carbon stock and CO₂ stock of forest was 33±1.0 ㎡ ha^-1, 108±5.0 Mg ha^-1 and 394±18 Mg ha^-1, respectively. Seedling and tree density of the plantation was 4,965 ha^-1 and 339 ha^-1 respectively. The forest carbon stock showed a positive relationship with biomass, tree diameter, height and basal area but no relationship with tree density. Canopy cover and tree diameter have a negative effect on seedling density and regeneration. In conclusion, the community forest has a stable population in each size class, sequestering a significant amount of carbon and CO₂ emitted from densely populated Kathmandu metro city as the forest biomass hence have a potentiality to mitigate the global climate change.

• Journal of Electrical Engineering and Technology
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• 제11권4호
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• pp.939-942
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• 2016

One of the most important characteristic curves of a solar cell is its current density-voltage (J-V) curve under AM1.5G insolation. Solar cell can be considered as a semiconductor diode, so a diode equivalent model was used to estimate its parameters from the J-V curve by numerical simulation. Active layer plays an important role in operation of a solar cell. We investigated the effect thicknesses and defect densities (N_d) of the active layer on the J-V curve. When the active layer thickness was varied (for N_d = 8×10¹⁷ cm^-3) from 800 nm to 100 nm, the reverse saturation current density (J_o) changed from 3.56×10^-5 A/cm² to 9.62×10^-11 A/cm² and its ideality factor (n) changed from 5.28 to 2.02. For a reduced defect density (N_d = 4×10¹⁵ cm^-3), the n remained within 1.45≤n≤1.92 for the same thickness range. A small increase in shunt resistance and almost no change in series resistance were observed in these cells. The low reverse saturation current density (J_o = 9.62×10^-11 A/cm²) and diode ideality factor (n = 2.02 or 1.45) were observed for amorphous silicon based solar cell with 100 nm thick active layer.