• 한국방사선학회논문지
• /
• 제15권2호
• /
• pp.125-130
• /
• 2021

AAPM CT 성능 팬텀에서 CT수 교정 삽입부의 각 핀과 물에 대응하는 유효원자번호 및 물리적 밀도에 대한 CT수에 관한 자료가 거의 없다. 따라서 자료화의 필요성이 제기되었다. 이 연구의 목적은 AAPM CT 성능 팬텀에서 CT수 교정 삽입부의 각 핀 및 물에 대하여 유효원자번호를 산출하고, 산출된 유효원자번호 및 물리적 밀도에 대한 CT수를 측정하여 비교분석하는데 있다. AAPM CT 성능 팬텀의 CT수 교정 삽입부에서 각 핀과 물의 유효원자번호 및 물리적 밀도에 관한 CT수의 자료를 획득하기 위하여, 먼저 각 핀과 물에 대한 유효원자번호를 산출하였다. 그리고 CT스캐너로 CT수 교정 삽입부를 스캔하여 CT슬라이스들을 획득하였다. 중심 CT슬라이스에서 각 핀과 물에 대하여 CT수들을 측정하였다. 결과로서, 유효원자번호에 대한 CT수들은 유효원자번호가 증가할수록 비선형적으로 증가와 감소를 반복하는 양상을 나타내었다. 그리고 물리적 밀도에 대한 CT수들도 물리적 밀도가 증가할수록 비선형적으로 증가와 감소를 반복하는 양상을 나타내었다.

• Korean Journal of Mathematics
• /
• 제9권1호
• /
• pp.21-28
• /
• 2001

We find bounds for the domination number of a tournament and investigate the sharpness of these bounds. We also find the domination number of a random tournament.

• Asian-Australasian Journal of Animal Sciences
• /
• 제18권10호
• /
• pp.1475-1478
• /
• 2005

Statistical analysis was conducted on sow stillbirth traits of three genotypes with 2,400 litters including the Erhualian, Large White and the $F_1$ cross of these two breeds. Number of stillborn piglets per litter in the Erhualian, Large White and the $F_1$ averaged 0.85, 0.31 and 0.70, and percentage born alive averaged 95.0%, 97.0% and 95.5%, respectively. Erhualian sows with a greater litter size also had a higher stillbirth rate. Results of analysis of variance indicated that genotype, parity, farrowing year${\times}$farrowing season interaction and total number born had highly significant effects on both number of stillborn piglets per litter and percentage born alive in sows (p<0.0001). Farrowing year had no significant effect on number of stillborn piglets per litter (p>0.05), and highly significant effect on percentage born alive (p<0.01). Farrowing season had highly significant effects on both number of stillborn piglets per litter and percentage born alive (p<0.01). From parity one to parity ten, least squares means for number of stillborn piglets per litter progressively increased with increasing parity and least squares means for percentage born alive progressively decreased with increasing parity. Sows that farrowed in winter had the highest number of stillborn piglets per litter and the lowest percentage born alive, sows that farrowed in autumn had the lowest number of stillborn piglets per litter and the highest percentage born alive. With increasing total number born, least squares means for number of stillborn piglets per litter markedly increased and least squares means for percentage born alive markedly decreased. Results from analysis of paternal half sibs indicated that the heritabilities for number of stillborn piglets per litter and percentage born alive were 0.110 and 0.124, and the genetic, phenotypic and environmental correlations between them were -0.989, -0.951 and -0.948, respectively. These results indicated that number of stillborn piglets per litter and percentage born alive were traits with the similar genetic background.

• 한국환경과학회지
• /
• 제22권3호
• /
• pp.347-358
• /
• 2013

The aerosol number concentration have measured with an aerodynamic particle sizer spectrometer(APS) at Gosan in Jeju Island, which is known as background area in Korea, from March 2010 to February 2011. The obtained results of asian dust events and non-asian dust period have been compared. The results show that the entire averaged aerosol number concentration from APS measurement during asian dust events and non-asian dust period are about 341 particles/$cm^3$ and 240 particles/$cm^3$, respectively. During asian dust events, the number concentration in small size ranges(${\leq}0.4{\mu}m$) are similar to non-asian dust period, however, those in large size ranges(${\geq}0.7{\mu}m$) are very higher than non-asian dust period. The contributions of the size resolved number concentration(23 channel in $0.25{\sim}10.0{\mu}m$) to total number concentration in that range are dramatically decreased with increased particle size. The contributions of smaller size ranges(${\leq}0.4{\mu}m$) during asian dust events are very low compared with non-asian dust period, on the other hand, those of larger size ranges(${\geq}0.4{\mu}m$) are higher than non-asian dust period. The number concentration in each size range are strongly correlated with the concentration in adjacent size range. And the total aerosol number concentration are depended on the number concentration in range of smaller than $0.58{\mu}m$ during non-asian dust period and asian dust events. On the other hand, $PM_{10}$ mass concentration has mainly affected with the number concentration in range of smaller than $1.0{\mu}m$ during non-asian dust period, however, during asian dust events, the mass concentration has mainly affected with the number concentration in range of $0.65{\sim}3.0{\mu}m$.

• 한국환경과학회지
• /
• 제21권4호
• /
• pp.535-543
• /
• 2012

The aerosol number concentration have measured with an aerodynamic particle sizer spectrometer(APS) at Gosan site, which is known as background area in Korea, from January to September 2011. The temporal variation and the size distribution of aerosol number concentration have been investigated. The entire averaged aerosol number concentration in the size range 0.25~32.0 ${\mu}m$ is about 252 particles/$cm^3$. The number concentration in small size ranges(${\leq}0.5{\mu}m$) are very higher than those in large size ranges, such as, the number concentration in range of larger than 6.5 ${\mu}m$ are almost zero particles/$cm^3$. The contributions of the number concentration to PM10 and/or PM2.5 are about 34%, 20.1% and 20.4% in the size range 0.25~0.28 ${\mu}m$, 0.28~0.30 ${\mu}m$ and 0.30~0.35 ${\mu}m$, respectively, however, the contributions are below 1% in range of larger than 0.58 ${\mu}m$. The monthly variations in the number concentration in smaller size range(<1.0 ${\mu}m$) are evidently different from the variations in range of larger than 1.0 ${\mu}m$, but the variations are appeared similar patterns in smaller size range(<1.0 ${\mu}m$), also the variations in range of larger than 1.0 ${\mu}m$ are similar too. The diurnal variations in the number concentration for smaller particle(<1.0 ${\mu}m$) are not much, but the variations for larger particle are very evident. Size-fractioned aerosol number concentrations are dramatically decreased with increased particle size. The monthly differences in the size-fractioned number concentrations for smaller size range(<0.7 ${\mu}m$) are not observed, however, the remarkable monthly differences are observed for larger size than 0.7 ${\mu}m$.

• 한국수학교육학회지시리즈E:수학교육논문집
• /
• 제29권1호
• /
• pp.1-18
• /
• 2015

수학교육에서 학생들의 수감각 발달을 강조하고 있지만 이에 대한 연구는 부족한 실정이며 초등학생에 국한된 경우가 많다. 이에 본 연구는 초등학생과 중학생을 대상으로 수감각 문제를 해결하는 방법을 분석함으로써, 수감각 지도방향에 대한 시사점을 제공하고자 하였다. 이를 위해 본 연구에서는 문제를 해결하는 방법으로 수감각을 활용하는 방법과 알고리즘을 활용하는 방법으로 분류하고, 검사지를 이용하여 학생들의 반응을 분석하였다. 그 결과 중학생들이 초등학생들에 비해 수감각 검사 점수가 높았으며, 문제해결 방법 중 수감각을 활용하는 비율도 높았다. 또한 성취도가 높은 학생들은 수감각과 알고리즘을 모두 활용하였으나 성취도가 낮은 학생들은 알고리즘을 활용하여 문제를 해결하려고 하는 경향이 강했다. 그리고 성취도가 높은 학생들은 초등학생에 비해 중학생이 상대적으로 수감각을 더 많이 활용하였으나, 성취도가 낮은 학생들끼리는 차이가 없었다. 마지막으로 수감각 구성 요소별로 수감각을 활용하는 비율에 차이가 있는 것으로 나타났다.

• Journal of Mechanical Science and Technology
• /
• 제19권8호
• /
• pp.1632-1648
• /
• 2005

The effects of Reynolds number on the non-nulling calibration of a typical cone-type five-hole probe have been investigated for the representative Reynolds numbers in turbomachinery. The pitch and yaw angles are changed from - 35 degrees to 35 degrees with an angle interval of 5 degrees at six probe Reynolds numbers in range between $6.60{\times}10^3\;and\;3.17{\times}10^4$. The result shows that not only each calibration coefficient itself but also its Reynolds number dependency is affected significantly by the pitch and yaw angles. The Reynolds-number effects on the pitch- and yaw-angle coefficients are noticeable when the absolute values of the pitch and yaw angles are smaller than 20 degrees. The static-pressure coefficient is sensitive to the Reynolds number nearly all over the pitch- and yaw-angle range. The Reynolds-number effect on the total-pressure coefficient is found remarkable when the absolute values of the pitch and yaw angles are larger than 20 degrees. Through a typical non-nulling reduction procedure, actual reduced values of the pitch and yaw angles, static and total pressures, and velocity magnitude at each Reynolds number are obtained by employing the calibration coefficients at the highest Reynolds number ($Re=3.17{\times}10^4$) as input reference calibration data. As a result, it is found that each reduced value has its own unique trend depending on the pitch and yaw angles. Its general tendency is related closely to the variation of the corresponding calibration coefficient with the Reynolds number. Among the reduced values, the reduced total pressure suffers the most considerable deviation from the measured one and its dependency upon the pitch and yaw angles is most noticeable. In this study, the root-mean-square data as well as the upper and lower bounds of the reduced values are reported as a function of the Reynolds number. These data would be very useful in the estimation of the Reynolds-number effects on the non-nulling calibration.

• 한국전자통신학회논문지
• /
• 제12권6호
• /
• pp.1181-1188
• /
• 2017

수체의 단수와 기본단수계는 RSA 암호계에서는 400자리 이상의 큰 수가 소수인지를 판별하는 소수판정법과 그 수를 소인수분해하는 데에 사용되는 다양한 수체선별법에 사용되며, 복소이차체를 기반으로 하는 암호계에서는 이데알의 곱셈과정과 류수(class number)를 계산하는 과정 등 다양한 암호계에서 사용되고 있다. 본 논문에서는 기본단수계를 이용하는 암호계의 구현시간과 공간을 줄이기 위하여, 수체의 기본단수계의 존재성을 증명한 Dirichlet의 정리와 몇 가지 기본단수계의 성질을 중심으로 우리가 제안하는 기본단수계의 생성 과정을 소개한다. 그리고 그에 따른 기본단수계의 H/W 구현의 시간과 공간을 최소화할 수 있는 효율적인 기본단수계의 생성알고리즘과 그 알고리즘을 H/W 상에서 구현한 결과를 제시한다.

• 대한수학교육학회지:수학교육학연구
• /
• 제19권4호
• /
• pp.513-530
• /
• 2009

이 연구에서는 초등학교 1-2학년 교육과정, 해설서, 및 그에 따른 교과서에 나타난 수 감각 지도 내용을 분석한다. 이를 위해 수 감각에 관한 선행연구를 메타분석하여 수 감각의 의미와 요소를 규명한 다음, 그것을 이용해서 교육과정, 해설서, 1-2학년 교과서에서의 수 감각 지도 내용을 비판적으로 분석한다. 수 감각은 기존의 전통적인 수에 관한 학습에서 강조되었던 수와 계산과 더불어 어림을 포함하여, 수와 계산이 필요한 맥락에 적용하는 능력을 강조하는 용어로, 내용 요소와 과정 요소로 구성된다. 이 두 요소를 바탕으로 교육과정, 해설서, 1-2학년 교과서를 분석한 결과, 수 감각의 범위가 불분명하고, 용어를 일관되게 사용하지 않고, 다루고 있는 요소가 제한적이며, 일관되지 않거나 빈약한 상태로 교과서에 구체화되어 있음을 알 수 있었다.

• Journal of Forest and Environmental Science
• /
• 제37권4호
• /
• pp.309-314
• /
• 2021

This study aimed to enhance seed productivity and secure genetic resources for Pinus densiflora for. multicaulis. We analyzed the characteristics of cone and seed generated by control pollination between Pinus densiflora (PD) and Pinus densiflora for. multicaulis (PDM). The highest number of cone scales (63.0) was obtained from the self-pollinated (sp) PDM clone B (PDM-sp-B), whereas the lowest number of cone scales (44.7) was obtained from two combinations designated as PDM-A×PD-075 and PDM-A×PD-0111. Both female parents of the hybrids were PDM-A. The highest seed production capacity (80.8) was obtained from the open-pollinated (op) PDM clone B (PDM-op-B). The seed potentials of PDM-B×PD-0111, PDM-op-A, and PDM-sp-B were 67.4, 66.5, and 63.1, respectively. The highest number of fertile scales (41.5) was obtained from PDM-op-B, and the lowest number of fertile scales (28.8) was obtained from PDM-A×PD-075. The total number of aborted ovules and 1st aborted ovules was not statistically significant in the mating design. The cross combination of PDM-B×PD-0111 had the highest number (34.8) of filled seeds and the lowest number of 2nd aborted ovules (5.2) and empty seeds (9). PDM-op-B had the highest number of developed seeds (47.6), although the number of empty seeds was the highest (41.2). Therefore, we conclude that the mating design of PDM-B×PD-0111 is useful for future breeding programs to improve seed yield of PDM. Our results showed that there was a strong correlation between the following two parameter pairs: number of scales and number of fertile scales, and the number of fertility scales and seeds potential (r=0.89 and r=0.84, respectively; both p<0.01).