• Journal of the Optical Society of Korea
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• 제15권3호
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• pp.209-215
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• 2011

A new iterative algorithm is developed to estimate LIDAR ratio for a thin cirrus cloud over an aerosol layer. First, the thin cirrus cloud is screened out and replaced by a modeled LIDAR signal and the extinction coefficients of the aerosol layer are derived using the Fernald backward method. These aerosol coefficients are referred as the "actual values". Second, the original LIDAR signal which includes the thin cirrus cloud is also inverted by the Fernald backward method down to the aerosol layer but using different LIDAR ratio for the thin cirrus cloud. Depending on the different assumptions about the LIDAR ratio of the thin cirrus cloud, different sets of aerosol extinction can be derived. The "actual values" which are found in the first step can be used to constrain this iterative progress and the correct LIDAR ratio of the thin cirrus cloud can be found. The detailed description of this method and retrieval examples are given in the paper. The cases compared with other methods are presented and the statistical result is also shown and agrees well with other studies.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 추계학술대회 논문집 Vol.14 No.1
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• pp.193-196
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• 2001

Single phase $CuInS_2$ thin film with the highest diffraction peak (112) at diffraction angle $(2\theta)$ of $27.7^{\circ}$ and the second highest diffraction peak (220) at diffraction angle $(2\theta)$ of $46.25^{\circ}$ was well made with chalcopyrite structure at substrate temperature of $70^{\circ}C$, annealing temperature of $250^{\circ}C$, annealing time of 60 min. The $CuInS_2$ thin film had the greatest grain size of $1.2{\mu}m$ and Cu/In composition ratio of 1.03. Lattice constant of a and c of that $CuInS_2$ thin film was 5.60 A and 11.12 A respectively. Single phase $CuInS_2$ thin films were accepted from Cu/In composition ratio of 0.84 to 1.3. P-type $CuInS_2$ thin films were appeared at over Cu/In composition ratio of 0.99. Under Cu/In composition ratio of 0.96, conduction types of $CuInS_2$ thin films were n-type. Also, fundamental absorption wavelength, the absorption coefficient and optical energy band gap of p-type $CuInS_2$ thin film with Cu/In composition ratio of 1.3 was 837 nm, $3.0{\times}104cm^{-1}$ and 1.48 eV respectively. When Cu/In composition ratio was 0.84, fundamental absorption wavelength, the absorption coefficient and optical energy band gap of n-type $CuInS_2$ thin film was 821 nm, $6.0{\times}10^4cm^{-1}$ and 1.51 eV respectively.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 추계학술대회 논문집
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• pp.193-196
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• 2001

Single phase CuInS$_2$ thin film with the highest diffraction peak (112) at diffraction angle (2$\theta$) of 27.7$^{\circ}$ and the second highest diffraction peak (220) at diffraction angle (2$\theta$) of 46.25$^{\circ}$ was well made with chalcopyrite structure at substrate temperature of 70 $^{\circ}C$, annealing temperature of 25$0^{\circ}C$, annealing time of 60 min. The CuInS$_2$ thin film had the greatest grain size of 1.2 ${\mu}{\textrm}{m}$ and Cu/In composition ratio of 1.03. Lattice constant of a and c of that CuInS$_2$ thin film was 5.60 $\AA$ and 11.12 $\AA$ respectively. Single phase CuInS$_2$ thin films were accepted from Cu/In composition ratio of 0.84 to 1.3. P-type CuInS$_2$ thin films were appeared at over Cu/In composition ratio of 0.99. Under Cu/In composition ratio of 0.96, conduction types of CuInS$_2$ thin films were n-type. Also, fundamental absorption wavelength, the absorption coefficient and optical energy band gap of p-type CuInS$_2$ thin film with Cu/In composition ratio of 1.3 was 837 nm, 3.0x10 $^4$ $cm^{-1}$ / and 1.48 eV respectively. When CuAn composition ratio was 0.84, fundamental absorption wavelength, the absorption coefficient and optical energy band gap of n-type CuInS$_2$ thin film was 821 nm, 6.0x10$^4$ $cm^{-1}$ / and 1.51 eV respectively.

• 한국지반공학회논문집
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• 제19권5호
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• pp.253-261
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• 2003

샌드드레인공법(SD공법)이나 고치환율의 샌드콤팩션파일공법(SCP공법)과 비교하여 저치환율SCP공법에 의해 개량된 복합지반의 역학거동은 모래말뚝과 점토지반 양방의 역학적 상호작용의 영향을 보다 현저하게 받는다. 따라서 본 공법의 적용에 있어서 침하저감효과나 모래말뚝 사이의 점토의 강도증가 등을 정확히 평가하기 위해서는 복합지반 내부에서의 모래말뚝과 점토와의 역학적 상호작용을 해명하여야 할 필요성이 있다. 본 연구에서는 저치환율의 모래말뚝이 타설된 복합지반에 대한 일련의 모형실험을 통하여 압밀중에 발생되는 모래말뚝과 점토 각각의 역학거동과 복합지반 내부에 대한 응력분담거동에 대하여 고찰하였다.

• 한국표면공학회지
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• 제41권3호
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• pp.109-113
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• 2008

High strength 7xxx series Al-Zn-Mg alloy have been investigated for using light weight automotive parts especially for bump back beam. The composition of commercial 7xxx aluminum has the Zn/Mg ratio about 3 and Cu over 2 wt%, but this composition isn't adequate for appling to automotive bump back beam due to its high resistance to extrusion and bad weldability. In this study the Zn/Mg ratio was increased for better extrusion and Cu content was reduced for better welding. With this new composition we investigated the effect of composition on the resistivity against stress corrosion cracking. As the Zn/Mg ratio is increased fracture energy obtained by slow strain rate test was decreased, which means degradation of SCC resistance. While the fracture energy was increased with Cu contents although it is below 1%, which means improvement of SCC resistance. These effects of composition change on the SCC resistivity were identified by observing the fracture surface and crack propagation.

• 한국세라믹학회지
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• 제42권1호
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• pp.16-21
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• 2005

The effect of additive composition, using AlN and $Er_{2}O_{3}$ as sintering additives, on the mechanical properties of liquid-phase-sintered, and subsequently annealed SiC ceramics was investigated. The microstructures developed were quantitatively analyzed by image analysis. The average thickness of SiC grains increased with increasing the $Er_{2}O_{3}/(AlN + Er_{2}O_{3})$ ratio in the additives whereas the aspect ratio decreased with increasing the ratio. The mechanical properties versus $Er_{2}O_{3}/(AlN + Er_{2}O_{3})$ ratio curve had a maximum; i.e., there was a small composition range at which optimum mechanical properties were realized. The best results were obtained when the ratio ranged from 0.4 to 0.6. The flexural strength and fracture toughness of the SiC ceramics were $550\~650\;MPa$ and $5.5\~6.5$ MPa${\cdot}m^{1/2}$, respectively.

• 한국도로학회논문집
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• 제19권5호
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• pp.77-88
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• 2017

PURPOSES : It is necessary to clarify the rheological properties of cement paste as a basic research in the development of mechanistic concrete mix design. The rheological properties of cement paste with different binder types, mix propositions, and with/without high range water reducers have been analyzed. METHODS : In this study, ordinary Portland cement, fly-ash, blast furnace slag, silica fume, and limestone powder were used as binders. The range of water-binder ratio was 0.3-0.5, and a total of 30 different mixes have been tested. The slump flow test, V-funnel test, and Dynamic Shear Rheometer (DSR) test were performed to analyze the rheological properties of cement paste. RESULTS : As a result of the slump flow test, it was found that the composition ratio of the binder contents greatly affected the paste flow when the high range water reducers were added. The results of V-funnel test showed that when the water-binder ratio was decreased without high range water reducers, the binder composition ratio had a large effect on the passing time of the V-funnel tester, but with high range water reducers the impact of the binder composition ratio was decreased. The slump flow and V-funnel have a certain relationship with the rheological factors (yield stress and plastic viscosity), but the correlation was not significant. Finally, we proposed the M-value considering the density and specific surface area of the binder. The correlation between rheological factors and M-value were better demonstrated than experimental values, but there is still a limit to predict the rheological factor in general mix design. CONCLUSIONS :In this study, the rheological properties of cement paste were analyzed. The binder type, composition ratio of binder, and with/without high range water reducers have combined to provide the complex effects on the rheological properties of cement paste. The correlation between the proposed M-value and rheological factor was found to be better than experimental results, but needs to be improved in the future.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2005년도 지반공학 공동 학술발표회
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• pp.443-452
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• 2005

The compaction pile methods with low replacement area ratio used sand(SCP) or gravel(GCP) has been usually applied to improvement of soft clay deposits. In order to design accurately compaction pile method with low replacement area ratio, it is important to understand the mechanical interaction between sand piles and clays and its mechanism during consolidation process of the composition ground. In this paper, a series of numerical analyses on composition ground improved by SCP and GCP with low replacement area ratio were carried out, in order to investigate the mechanical interaction between sand piles and clays. The applicability of numerical analyses, in which and elasto-viscoplastic consolidation finite element method was applied, could be confirmed comparing with results of a series of model tests on consolidation behaviors of composition ground improved by SCP. And,through the results of the numerical analyses, each mechanical behaviors of compaction piles and clays in the composition ground during consolidation was elucidated, together with stress sharing mechanism between compaction piles and clays.

• Nuclear Engineering and Technology
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• 제50권7호
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• pp.1120-1130
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• 2018

An analysis of a pyroprocessing safeguards methodology employing the Pu-to-$^{244}Cm$ ratio is presented. The analysis includes characterization of representative used nuclear fuel assemblies with respect to computed nuclide composition. The nuclide composition data computationally generated is appropriately reformatted to correspond with the material conditions after each step in the head-end stage of pyroprocessing. Uncertainty in the Pu-to-$^{244}Cm$ ratio is evaluated using the Geary-Hinkley transformation method. This is because the Pu-to-$^{244}Cm$ ratio is a Cauchy distribution since it is the ratio of two normally distributed random variables. The calculated uncertainty of the Pu-to-$^{244}Cm$ ratio is propagated through the mass flow stream in the pyroprocessing steps. Finally, the probability of Type-I error for the plutonium Material Unaccounted For (MUF) is evaluated by the hypothesis testing method as a function of the sizes of powder particles and granules, which are dominant parameters to determine the sample size. The results show the probability of Type-I error is occasionally greater than 5%. However, increasing granule sample sizes could surmount the weakness of material accounting because of the non-uniformity of nuclide composition.

• Journal of Nutrition and Health
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• 제28권8호
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• pp.706-716
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• 1995

This study was undertaken to investigate the influence of age and dietary linolenic acid content and the linolenic acid/linoleic acid (LAN/LA) ratio on the brain lipid composition and membrane-bound enzyme, acetylcholinesterase(AchE) activities. AchE was selected as a test case for the relationship between cell lipid composition and cell membrane function. The male rats were fed diets with 0.2, 0.4, 0.6 of LNA/LA ratio within 8% LNA(H-LNA) or 4% LNA(L-LAN) of total fatty acid content for different feeding period(1, 4, 12 month). The fats used s source were sesame oil, perilla oil, soybean oil and beef tallow. The AchE activity of brain crude synaptosomal fraction was reduced with advancing age, showing 20-30% reduction in 12M compared with 1 M, and the P/C ratio was reduced in old rats. In 1 and 4 monthed rats, AchE activites was higher in H-LAN-0.2 and L-LNA-0.2 and 0.4 group. In accordance with rising of AchE activities was higher in H-LNA-0.2 and L-LNA-0.2 and 0.4 group. In accordance with rising of AchE activities, the PC/PE ratio increasedin those groups. Paricularly in L-LNA, the PC/PE ratio increased as the AchE activites for decline of membrane fluidity with increasing cholesterol and decreasing P/C ratio when rats were old. Also, AchE activity increaed with increasing PC/PE ratio which depended on the dietary LNA/LA ratio within each LNA content. Therefore, it is concluded that the lipid composition of cell membrane influenced the AchE activiteis, which was mediated by aging and the modification of dietary LNA/LA ratio.