• Journal of Medicine and Life Science
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• 제20권1호
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• pp.21-31
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• 2023

We aimed (a) to investigate the associations between age, body mass index (BMI), and breast size with mammographic density based on the breast imaging reporting and data system (BI-RADS) and volumetric breast density measurement (VBDM) with Volpara, (b) to evaluate the associations of age, BMI, and breast size with fibroglandular tissue volume (FGV), and (c) to demonstrate the association of mammographic density grade with FGV. From April 2012 to May 2012, 1,203 women consecutively underwent mammography, and their breast density was calculated using the density grade and volume determined by Volpara. In total, 427 women were included in this study. The BMI and breast size of the 427 women were determined. The associations between mammographic density and age, BMI, and bra cup size were assessed. In addition, the associations between FGV and age, BMI, bra cup size, and mammographic density were assessed. The mean age of the women was 51 years (range, 27-83). Age was associated with mammographic density based on BI-RADS (P<0.0001), and both age and BMI were associated with mammographic density based on Volpara (P<0.0001). The mean FGV significantly decreased as age increased (P<0.0001) and increased as BMI and bra cup size increased (P<0.0001 and P=0.0007, respectively). Age was associated with mammographic density, according to both the BI-RADS and VBDM; however, BMI was only associated with mammographic density based on the VBDM. Larger FGV was associated with younger age, higher BMI, larger bra cup size, and higher mammographic density

• Journal of the Korean Physical Society
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• 제73권10호
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• pp.1584-1588
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• 2018

During hyperthermia therapy, cancer cells are heated to a temperature in the range of $40{\sim}45^{\circ}C$ for a defined time period to damage these cells while keeping healthy tissues at safe temperatures. Prior to hyperthermia therapy, the amount of heat energy transferred to the cancer cells must be predicted. Among various non-invasive methods, the thermal prediction method using the specific absorption rate (SAR) is the most widely used method. The existing methods predict the thermal distribution by using a single constant for the mass density in one organ through assignment. However, because the SAR and the bio heat equation (BHE) vary with the mass density, the mass density of each organ must be accurately considered. In this study, the mass density distribution was calculated using the relationship between the Hounsfield unit and the mass density of tissues in preceding research. The SAR distribution was found using a quasi-static approximation to Maxwell's equation and was used to calculate the potential distribution and the energy distributions for capacitive RF heating. The thermal distribution during exposure to RF waves was determined by solving the BHE with consideration given to the considering contributions of heat conduction and external heating. Compared with reference data for the mass density, our results was within 1%. When the reconstructed temperature distribution was compared to the measured temperature distribution, the difference was within 3%. In this study, the density distribution and the thermal distribution were reconstructed for the agar phantom. Based on these data, we developed an algorithm that could be applied to patients.

• 대한물리의학회지
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• 제15권1호
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• pp.95-104
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• 2020

PURPOSE: A prospective study was conducted to investigate the correlation between the inspiration ability, bone mineral density, lumbar muscle strength, and muscular endurance for the national softball athletes in the national training center. METHODS: The general characteristics of study subjects, inspiration ability, bone mineral density, muscle strength, and muscular endurance data were analyzed using descriptive statistics. In addition, the Pearson product moment correlation was performed to investigate the correlation between the inspiratory capacity, bone mineral density, muscle strength, and muscular endurance. RESULTS: The inspiration, flow rates, and volume were not correlated with the bone mass and bone mineral density. Inspiration and the flow rates and volume were not correlated with the bone mass and bone mineral density. On the other hand, inspiration was correlated with the Extensor muscles (r=.464, p=.006) at an angular velocity of 60°/s and the flexors (r=.463, p=.006) and extensor muscles (r=.615, p<.001) at an angular velocity of 180°/s. The flow rate was also correlated with the extensor muscles (r=.444, p=.009) at an angular velocity of 60°/s and with flexor muscles (r=.432, p=.011) and extensor muscles (r=.589, p<.001) at an angular velocity of 180°/s. Finally, the volume was correlated at the extensor muscles at an angular velocity of 180°/s (r=.534, p=.001). CONCLUSION: The correlation between the inspiratory capacity, bone mineral density, muscle strength, and muscular endurance of softball athletes did not correlate with the bone mass and bone density. On the other hand, the lumbar muscle strength increased with increasing inspiratory capacity.

• 한국지반공학회논문집
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• 제38권10호
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• pp.41-48
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• 2022

전단파 속도를 기반으로 포화 지반의 최대 전단탄성계수를 산정하는데 이용되는 매질의 밀도가 명확하지 않아 이를 결정하고자 검증식을 구성하고, 시나리오를 수립하여 실내 실험결과와 비교하였다. 매질의 밀도는 포화, 습윤, 건조, 수중 밀도 조건으로 가정하였고, 각 경우별 건조지반 전단파속도 대비 포화지반 전단파속도의 비를 산정하였다. 포화 밀도 가정시 전단파속도 비는 공진주 실험 결과에 의한 전단파속도 비와 일치하였고, 습윤 밀도 가정시에는 벤더엘리먼트 실험 결과에 의한 값과 일치하였다. 이는 특성 주파수를 경계로 흙입자와 유체의 거동을 정의하는 Biot(1956)의 이론과 일치하는 결과이며, 일반적으로 고려되는 지진의 주파수 범위를 고려한다면 포화 지반에서는 포화 밀도를 적용하는 것이 타당할 것으로 사료된다.

• Biotechnology and Bioprocess Engineering:BBE
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• 제8권6호
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• pp.349-353
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• 2003

The physiological characteristics of cultures of very high cell mass (e.g. 10g cell mass/L), termed“ultrahigh cell density cultures”is reviewed. A close relationship was found between the length of the optical path (OP) in flat-plate reactors and the optimal cell density of the culture as well as its areal (g m$\^$-2/ day$\^$-1/) productivity. Cell-growth inhibition (GI) unfolds as culture density surpasses a certain threshold. If it is constantly relieved, a 1.0cm OP reactor could produce ca. 50% more than reactors with longer OP, e.g. 5 or 10cm. This unique effect, discovered by Hu et al. [3], is explained in terms of the relationships between the frequency of the light-dark cycle (L-D cycle), cells undergo in their travel between the light and dark volumes in the reactor, and the turnover time of the photosynthetic center (PC). In long OP reactors (5cm and above) the L-D cycle time may be orders of magnitude longer than the PC turnover time, resulting in a light regime in which the cells are exposed along the L-D cycle, to long, wasteful dark periods. In contrast, in reactors with an OP of ca. 1.0 cm, the L-D cycle frequency approaches the PC turnover time resulting in a significant reduction of the wasteful dark exposure time, thereby inducing a surge in photosynthetic efficiency. Presently, the major difficulty in mass cultivation of ultrahigh-density culture (UHDC) concerns cell growth inhibition in the culture, the exact nature of which is awaiting detailed investigation.

• 천문학논총
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• 제13권1호
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• pp.135-147
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• 1998

We have simulated the interaction of supernova remnants with constant ambient medium to explore the dynamics of Type Ia supernova remnant. We assumed the supernova ejecta density distribution of the central constant and the outer power-law density distribution$({\rho}{\propto}{\gamma}^{-n})$. We have calculated four different cases with different n. By scaling the length and time scales from the initial parameters-ejecta mass, ejecta energy, the ambient density, we could compare effects of the different density distribution of the ejecta on the dynamics of the SNRs. The radius of the outer forward shock converges the Sedov-Talyor solution at t' = 2.3 when the swept-up mass is 8 times of the ejecta mass. On the other hand, the motion of the reverse shock are largely affected by n. The ejecta with smaller n takes comparably long time to thermalize the whole ejecta at $t'{\simeq}5.3,\;M_{sw}{\simeq}18M_{ej}$. We have applied our calculated results to obtain the ejecta density distributions of Tycho and SN1006 with $n{\simeq}6$.

• 한국지구물리탐사학회:학술대회논문집
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• 한국지구물리탐사학회 2003년도 Proceedings of the international symposium on the fusion technology
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• pp.379-382
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• 2003

In gravity data correction process, mass effect of the upper part of base level is removed with Bouguer density. Usually, Bouguer density is estimated as a mean density in the field area. But, this may causes a serious problem when ore body is in the area. To overcome this problem, we tried to apply a new method mixing up mass corrections and inversion (3DGTI). 3-D Gravity Terrain Inversion (3DGTI) includes information of topography and distribution of Bouguer density. For this method does not remove the mass effect above base level, it is no longer useless to use Bouguer density. Numerical model tests have shown that the 3DGIT successfully retrieves the anomalous subsurface density distribution of both surface and deeper layers. Model tests shows that this method shows better results than those of conventional one, especially when main target is ore body. The inversion result well delineates the three-dimensional shape of the intruded granite body and basement.

• 대한물리의학회지
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• 제14권3호
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• pp.134-141
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• 2019

PURPOSE: This study conducted aA forward-looking study of elite water polo athletes, who trained at National Training Center, was conducted to determine the correlation between the incidence of sports injuries and the bone density among national water polo players. METHODS: Data on the general characteristics of all study subjects were analyszed usingin descriptive statistics. The incidence of sports injuries was calculated from the incidence of sports injuries per 1,000 hours and the incidence of sports injuries resulting from exposure to 1,000 training sessions. The incidence of all sports injuries was calculated with a 95% confidence interval. Furthermore, Pearson's correlation was calculated conducted to determine the correlation between sports injuries and bone density, bone mass and body composition. RESULTS: Water polo athletes suffered a total of 127 sports injuries in the three-year period, while the athletes suffered 3.5 sports injuries each year. The Ooverall injury rate of 3.2(95% CI 2.68-3.81) per 1,000h, 18.0(15% CI 14.89-21.16) of sports injuries per 1,000AE. For all athletes, 50.4% of the injuries were classified as mild, followed by moderate (26.8%) and severe (22.8%). The lower the bone density in all areas of sports injuries, the higher the incidence of sports injuries. In addition, and the lower the bone mass in all areas except for light injuries, the higher the incidence of sports injuries. CONCLUSION: In tThe correlation between sports injuries and bone density and bone composition of water polo athletes, revealed a significant correlation between the bone density and bone mass were statistically significant, and the lower the bone density and bone mass, the higher the incidence of sports injuries.

• 천문학회보
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• 제36권1호
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• pp.47.1-47.1
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• 2011

We studied the evolution of the two mass components system with NFW initial density distribution by direct integration of the Fokker-Planck equations. The low mass component is regarded the dark matter particles while the high mass component is assumed to be conglomerates of baryonic matter in order to depict the 'stars'. While the true mass ratio between these two types of particles should be extremely large, our adopted mass ratio is about 1000 beyond which the dynamical evolution and density distribution tend to converge. Since the dynamical evolution is dominated by the dynamical friction, the high mass component slowly moves toward the central part, and eventually undergoes the core collapse. The system reaches the core-collapse at about $7.1{\times}10^{-3}$ $t_{fh}$ in NFW models, where $t_{fh}$is the dynamical friction time at half-mass radius. The distribution of the high mass component is well fitted by the Sersic profiles or modified Hubble profile when the mass segregation is established. From these results, the surface brightness of elliptical galaxies may be explained by the high mass component experiencing dynamical friction by the dark matter particles. In order for the mass segregation to be effective within Hubble time, the mass of the luminous component should be greater than $10^5M_{\bigodot}$.

• 한국컴퓨터정보학회논문지
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• 제26권8호
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• pp.209-220
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• 2021

지방제외체질량(lean mass) 및 지방량(fat mass)과 같은 체성분이 골밀도에 미치는 영향은 매우 복잡하고 다양하게 나타나는 것으로 알려져 있다. 본 연구에서는 전국민을 대상으로 한 표본조사로부터 얻은 질병관리본부의 국민건강영양조사 2008-2011년 자료를 이용하여 50세 이상 남성(N=2,139) 및 폐경후여성(N=2,193)에서 체성분과 골밀도와의 관련성에 대해 조사하고자 하였다. 골다공증약물을 사용한 경우 및 골밀도에 영향을 미치는 질환 및 악성질환 등이 있는 대상은 제외하였다. 신체계측, 설문조사, 혈액검사 등과 함께 이중에너지흡수방사선을 이용하여 요추 및 대퇴골에서 골밀도를 측정하였고, 총지방제외체질량(TLM; total lean mass), 총지방량(TFM; total fat mass), 몸통지방량(TrFM; truncal fat mass) 등을 측정하였다. 체성분 지표들과 요추 및 대퇴골 골밀도는 유의한 양의 상관관계를 보였다. 연령, 체질량지수, 월 가구수입, 교육수준, 신체활동, 1일 칼슘섭취량, 혈중 비타민 D 농도를 포함하는 다중회귀분석을 시행한 결과 남녀 모두에서 TLM이 증가할수록 요추 및 대퇴골 골밀도가 유의하게 증가하였다. TLM의 가장 낮은 사분위수에 해당하는 군에서 요추 및 대퇴골 골밀도는 남녀 모두에서 다른 사분위수에 해당하는 군에 비해 유의하게 낮았다. TrFM은 위의 교란요인들을 보정한 이후 남성에서는 대퇴골전체 골밀도와 여성에서는 대퇴골경부 골밀도와 음의 상관관계를 보였다. 결론적으로 TLM은 50세 이상 남성 및 폐경후여성에서 골밀도를 유지하는데 매우 중요한 인자임을 확인할 수 있었다.