• 충청수학회지
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• 제27권4호
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• pp.553-562
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• 2014

In this paper we study of densities of the 4-rank of narrow ideal class groups of real quadratic function fields over the rational function field $\mathbb{F}_q(T)$ when $q{\equiv}3$ mod 4.

• 환경생물
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• 제24권3호
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• pp.258-267
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• 2006

본 연구는 경상남도 사천시 삼천포 항을 중심으로 인근의 40개의 조사정점을 선정하여 해수와 저질토에서 해양종속영양세균, E. coli, 그리고 Salmonella와 Shigella의 분포를 2003년 7월부터 12월가지 3차에 걸쳐 실시하였다. 본 연구의 조사기간(2003년 $7{\sim}12$월)중 삼천포만 인근해역의 조사정점에서 해양 종속영양세균의 분포는 $1.7{\pm}0.9{\times}10^3{\sim}2.4{\pm}0.9{\times}10^5CFUmL^{-1}$의 범주에서 변화하였으며, 정점 34에서 9월에 가장 높은 값을 나타냈다. 전반적으로 9월이 7월과 12월에 비해 모든 정점에서 다소 높은 값을 보였다. 저질토에서 혐기성 세균의 분포는 $2.2{\pm}0.2{\times}10^3{\sim}2.0{\pm}0.2{\times}10^5CFUg^{-1}dry$ wt.의 범주에서 변화하였다. 혐기성 세균의 경우 외해 정점에서는 내만에 위치한 정점들보다 년 중 낮은 균체수를 유지하고 있어 물리, 화학적인 환경요인들에 의해 별 영향인 없음을 알 수 있다. E. coli의 분포는 해수의 경우, 7월중에만 사천만 인근(St. 1, 2, 3, 4),진주만과 창선도 인근 (St. 15, 23, 31), 삼천포항 인근(St. 14)에서 검출되고 9월과 12월에는 전 정점에서 전혀 검출되지 않았다. 저질토의 경우, 7월에 사천만 인근(St. 1, 2)과 창선도 인근(St. 16, 31)에서만 검출 되었다. Salmonella와 Shigella의 분포는 해수와 퇴적토에서 7월과 9월에 일부 해역에서만 검출되었다.

• 대한화학회지
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• 제54권1호
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• pp.71-76
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• 2010

298.15~318.15 K 온도에서 디지탈 진동 U-tube densimeter 와 Ubbelohde 모세관 점성계을 사용하여 2-브로모프로판/메탄올 이성분 혼합물의 밀도와 점성도를 측정하였다. 온도와 농도에 대한 밀도와 점성도 상호 의존 관계를 조사하였다. 이성분 혼합물의 여분 몰부피와 여분 점성도를 실험으로 얻어진 밀도와 점성돌로부터 계산하여 구하였다. 모델이 실험치와 잘부합됨을 발견하였다.

• Journal of electromagnetic engineering and science
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• 제12권4호
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• pp.260-270
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• 2012

This work aims to present a theoretical analysis of the electric and magnetic surface current densities of a circular microstrip antenna (CMSA) as a body of revolution. The rigorous analysis of these problems begins with the application of the equivalence principle, which introduces an unknown electric current density on the conducting surface and both unknown equivalent electric and magnetic surface current densities on the dielectric surface. These current densities satisfy the integral equations (IEs) obtained by canceling the tangential components of the electric field on the conducting surface and enforcing the continuity of the tangential components of the fields across the dielectric surface. The formulation of the radiation problems is based on the combined field integral equation. This formulation is coupled with the method of moments (MoMs) as a numerical solution for this equation. The numerical results of the electric and magnetic surface current densities on the outside boundary of a CMSA excited by $TM_{11^-}$ and $TM_{21^-}$ modes are presented. The radiation pattern is calculated numerically in the two principle planes for a CMSA and gives a good results compared with measured results published by other research workers.

• 천문학회지
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• 제34권1호
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• pp.25-29
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• 2001

We have constructed a non-spherical model for the hot oxygen corona of Mars by including the effects of planetary rotation and diurnal variation of the Martian ionosphere. Exospheric oxygen densities are calculated by integrating ensemble of ballistic and escaping oxygen atoms from the exobase over the entire planet. The hot oxygen atoms are produced by dissociative recombination of $O^+_2$, the major ion in the Martian ionosphere. The densities of hot oxygen atoms at the exobase are estimated from electron densities which have been measured to vary with solar zenith angle. Our model shows that the density difference of hot oxygen atoms between noon and terminator is about two orders of magnitude near the exobase, but reduces abruptly around altitudes of 2000 km due to lateral transport. The diurnal variation of hot oxygen densities remains significant up to the altitude of 10000 km. The diurnal variation of the hot oxygen corona should thus be considered when the upcoming Nozomi measurements are analyzed. The non-spherical model of the hot oxy-gen corona may contribute to building sophisticate solar wind interaction models and thus result in more accurate escaping rate of oxygens from Mars.

• Corrosion Science and Technology
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• 제16권3호
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• pp.109-114
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• 2017

Monitoring of corrosion is in most cases based on simulation of environmental conditions on a large and complex structure such as a buried pipeline using a small probe, and the measurement of thermodynamics and kinetics of corrosion processes occurring on the probe surface. This paper presents a hybrid corrosion monitoring probe designed for simulating deteriorating conditions wrought by disbonded coatings and for measuring current densities and distribution of such densities on a simulated pipeline surface. The concept of the probe was experimentally evaluated using immersion tests under cathodic protection (CP) in high resistivity aqueous solution. Underneath the disbonded area, anodic currents and cathodic currents were carefully measured. Anodic current densities were used to calculate metal loss according to Faraday's law. Calculated corrosion patterns were compared with corrosion damage observed at the surface of the probe after a series of stringent tests. The capability of the probe to measure anodic current densities under CP, without requiring interruption, was demonstrated in high resistivity aqueous solution. The pattern of calculated metal loss correlated well with corrosion products distribution observed at the array surface. Working principles of the probe are explained in terms of electrochemistry.

• 천문학회지
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• 제33권2호
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• pp.127-135
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• 2000

We investigate the effects of planetary rotation on the exospheres of the earth and Mars with simple collisionless models. We develope a numerical code that computes exospheric densities by integrating velocity functions at the exobase with a 10 point Gauss method. It is assumed in the model that atoms above the exobase altitude move collisionlessly on an orbit under the planet's gravity. Temperatures and densities at the exobase over the globe are adopted from MSIS-86 for the earth and from Bougher et al's MTGCM for Mars. For both the earth and Mars, the rotation affects the exospheric density distribution significantly in two ways: (1) the variation of the exospheric density distribution is shifted toward the rotational direction with respect to the variation at the exobase, (2) the exospheric densities in general increase over the non-rotating case. We find that the rotational effects are more significant for lower thermospheric temperatures. Both the enhancement of densities and shift of the exospheric distribution due to rotation have not been considered in previous models of Martian exosphere. Our non-spherical distribution with the rotational effects should contribute to refining the hot oxygen corona models of Mars which so far assume simple geometry. Our model will also help in analyzing exospheric data to be measured by the upcoming Nozomi mission to Mars.

• 대한기계학회논문집
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• 제18권3호
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• pp.670-680
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• 1994

The thermophysical properties of Non-Newtonian fluid as the function of the temperature and the concentration are needed in many rheological heat transfer and fluid mechanics problems. The present work investigated the effects of the concentration and the temperature on the thermophysical properties of purely-viscous Non-Newtonian fluids such as the isobaric thermal expansion coefficient, density, zero-shear-rate viscosity, and zero-shear-rate dynamic viscosity within the experimental temperature range from $25^{\circ}C$ to $55^{\circ}C$. The densities of the test fluids were determined as the function of the temperature by utilizing a reference density and the least square equation for the measured isobaric thermal expansion coefficient. As the concentration of purely-viscous Non-Newtonian fluid was increased up to 10,000 wppm, the densities were proportionally increased up to 0.4%. The zero-shear-rate viscosities of test fluids were measured before and after the measurements of the first thermal expansion coefficients and the densities of Non-Newtonian fluid. Even though they were changed up to approximately 22% due to thermal aging and cycling, they had no effects on the thermal expansion coefficients and the densities of Non-Newtonian fluid. The zero-shear-rate dynamic viscosities for purely-viscous Non-Newtonian fluids were compared with the values for distilled water. They showed the similar trend with the zero-shear-rate viscosities due to small differences in the densities for both distilled water and purely-viscous Non-Newtonian fluid.

• 한국작물학회지
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• 제21권2호
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• pp.250-257
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• 1976

재식밀도를 달리한 조건에서 적엽처리가 대두품종의 수량 및 수량구성요소에 미치는 영향을 알고저 6월1일과 6월20일에 $\textrm{m}^2$당 80본, 40본, 27본 및 20본이 되도록 재식밀도를 조절 파종하고 개화시기에 잔여엽수가 상부로부터 각각 1,2,3,5,7엽이 되도록 하위엽을 적엽처리하고 무적엽의 표준구를 포함하는 6처이로 하여 시험을 실시하였는데 그 결과를 요약하면 다음과 같다. 1. 표준구에서의 최적엽면적지수는 파종기에 따라 다르며 광교에 있어서는 개화시에 LAI가 4~5이고 개화후 30일에는 5~6이었으며 SRF-300에 있어서는 개화시에 2.5~6.0이고 개화 30일후에는 6~7이었다. 2. 종실수량은 재식밀도가 낮은 경우에는 적엽처리에 의하여 직선적으로 감소되었으나 재식밀도가 $\textrm{m}^2$당 40본이상으로 높은 경우에는 수량과 착엽수사이에 유의적인 곡선효과가 인정되어 하위부의 경미한 적엽처리를 하므로서 표준에 비하여 광교에서는 25~35%, SRF-300에서는 13~32%의 증수를 보였다. 3. 적엽처리시에 수량에 가장 크게 영향하는 수량구성요소는 전체적으로 볼때 식물체당 협수이며 다음으로 6월1일 파종구에서 재식밀도가 감소됨에 따라서 광교에서는 립중의 효과가 증대되었고 SRF-300에서는 수량에 영향하는 임실율의 비중이 현저히 증대되었다.

• 대한방사선기술학회지:방사선기술과학
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• 제15권1호
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• pp.99-105
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• 1992

Visual evaluation of rib shadow and lung marking during high voltage chest radiography. The Purpose of this study is to improvement of visual discrimination of pulmonary structures on the conventional chest radiogram. The author prepared an artificial lung using an acryl plate, 8 cm in thickness, which is nearly equivalent to human lung, and 0.6 cm thickness of an aluminum plate for an artificial rib, and 0.5 cm of an acryl plate as a pulmonary vessel as well. And they were used as objects for experimental radiograms. This study performed with gradual increasing densities of film bases in the sequences of densities of 0.6, 0.9, 1.1 and 1.3. We made two combinations of images after multiple and regular cuts, with width of 1 cm, of 4 radiograms at the above mentioned densities of film bases. One image consisted of alternative combination of radiograms taken at densities of 0.6 and 1.3, and the other did at 0.9 and 1.1. The latter image provided better visual perception of pulmonary structures than the former. Experimental radiograms were also taken with 60 kV and 120 kV respectively. After careful evaluation and comparison to images taken on varieties of different densities with combinations and kV, the author had a conclusion that it is advisable to use a high kV X-ray which makes rib shadow subtle, for better visual delineation of pulmonary structures behind ribcage, eventhough contrast of pulmonary structures are decreased at high kV radiogram.