• Title/Summary/Keyword: low-mass

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DUST SHELL MODELS FOR LOW MASS-LOSS RATE OXYGEN-RICH AGB STARS

  • SUH KYUNG-WON
    • Journal of The Korean Astronomical Society
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    • v.38 no.2
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    • pp.267-270
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    • 2005
  • We investigate the spectral energy distributions (SEDs) of low mass-loss rate O-rich asymptotic giant branch (AGB) stars using the infrared observational data including the Infrared Space Observatory (ISO) data. Comparing the results of detailed radiative transfer model calculations with observations, we find that the dust formation temperature is much lower than 1000 K for standard dust shell models. We find that the superwind model with a density-enhanced region can be a possible alternative dust shell model for LMOA stars.

Relation of the Blood Pressure, Lipids and Body Mass Index by Smoking Status Among Adolescents (청소년의 흡연과 혈압, 지질 및 체질량 지수와의 관계)

  • Byeon, Young-Soon;Lee, Hea-Shoon
    • Journal of Korean Academy of Nursing
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    • v.37 no.6
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    • pp.1020-1026
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    • 2007
  • Purpose: This study was to investigate the relationship between blood pressure, lipids and body mass index by smoking status among adolescents. Methods: This study was designed as a descriptive correlational study. General and smoking characteristics were collected using a questionnaire. The smoking group consisted of 42 (33%) students and the non smoking group 85 (67%) students. Blood pressure, lipids, height and weight were measured, and body mass index was calculated to $kg/m^2$. The collected data was analyzed by the n(%), ${\chi}^2-test$, t-test and Pearson correlation coefficient (SPSS 12.0). Results: 1. The smoking level was different between grade, smoking status among the family, the contentment of their relationship with their parents, school life and teachers. 2. The smoking group's systolic blood pressure, total cholesterol, triglyceride, low density lipoprotein cholesterol and body mass index were higher than those of the non smoking group. 3. The smoking amount had a significant positive correlation between total cholesterol and low density lipoprotein cholesterol. Conclusion: The result of this study offered basic data to develop intervention programs to prevent hypertension and hyperlipidemia in smoking adolescents.

Observation of Peptide-Ion Generation by Laser-Induced Surface Heating from Tungsten Silicide Surfaces

  • Kim, Shin-Hye;Park, Sun-Hwa;Song, Jae-Yong;Han, Sang-Yun
    • Mass Spectrometry Letters
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    • v.3 no.1
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    • pp.18-20
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    • 2012
  • We report observation of laser desorption/ionization (LDI) of peptides from flat surfaces of tungsten silicide ($WSi_2$). In contrast to MALDI (matrix-assisted laser desorption/ionization) and SALDI (surface-assisted laser desorption/ionization) mass spectrometry, this study did not utilize any matrices and surface nanostructures. In this work, LDI on $WSi_2$ surfaces is demonstrated to cover a mass range up to 1,600 Da (somatostatin; monoisotopic mass = 1637.9 Da). In addition, it exhibited a high sensitivity, which could detect peptides, which could detect peptides of low femtomole levels (20 fmol for angiotensin II). The observed LDI process was discussed to be largely thermal, more specifically, due to laser-induced surface heating that is most likely promoted by the low thermal diffusivity (${\kappa}$) of $WSi_2$ substrate.

Mass Customization and the Level of Customers' Needs for Beauty Salon (미용실 고객의 매스 커스터마이제이션 요구 수준)

  • Kwon, Tae-Shin;Kim, Yong-Sook
    • The Research Journal of the Costume Culture
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    • v.20 no.1
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    • pp.1-17
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    • 2012
  • The purposes of this study were to analyze factors of mass customization for hair salon's customers and to identify the differences among groups segmented by mass customization level. The self-administered questionnaire was used for data collection. The respondents were 423 women using hair salons. Factors of hair salon's mass customization implementation were sanitary condition & hair salon's staff, hair styling technique, communication service, tangible service, monetary support, convenience service, and visible service. Hair salon's customers were categorized into the high-level of needs group, the middle-level of needs group, and the low-level of needs group. The high-level of needs group consisted of university students or women with a higher education or higher income. This group selected beauty salons by the promotion or advertisements, preferred their own unique hair style or a little-fashionable hair style, and showed a lower level of patronage. The middle-level of needs group consisted of university students or women with a higher education or higher incomes. They selected hair salons by service prices, preferred a basic hair style, and showed a midium level of patronage. The low-level of needs group consisted of women with lower education or lower income. They selected beauty salons by career of hair dressers or the promotion or advertisement, preferred highly fashionable hair style, and showed high level of patronage.

Role of Bar Structures in Galactic Nuclear Activities

  • Oh, Seul-Hee;Yi, Suk-Young K.;Oh, Kyu-Seok
    • The Bulletin of The Korean Astronomical Society
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    • v.36 no.1
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    • pp.60.2-60.2
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    • 2011
  • Galactic bars are supposed to be a channel of gas inflow to the galactic center and thus possibly help nuclear star-formation and AGN activities. However, previous studies based on small local samples did not agree with this expectation. We find it necessary to examine the expectation using a large sample and so investigate the effects of bar structures on galactic nuclear activities, based on the Sloan Digital Sky Survey (SDSS) DR7. We used 6,348 late-type galaxies brighter than Mr = -19.0 in the redshift range $0.01{\leq}z{\leq}0.05$. Late-type galaxies are visually classified into barred or unbarred galaxies using SDSS color composite images. We compare the fractions of galaxies showing star-formation and AGN activities among barred and unbarred galaxies as a function of optical color, stellar mass, and black-hole mass. We have found that bar enhances nuclear star-formation activity on galaxies having low stellar mass, and low black-hole mass. This effect is stronger in redder galaxies. In the case of AGN, bar effects are higher in intermediate-mass galaxies. Bars also have an effect on the strength(!) of the star-formation and AGN activity in our sample as well. Thus, it seems that nuclear activities are powered by gas inflow from galactic bar structures perhaps not always but under certain conditions.

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Comparison of Aerobic Fixed-film Process Response to Quantitative and Hydraulic Shock for the Same Increases in Mass Loading (호기성 고정생물막반응기에서 동일 질량부하의 수리학적 및 농도충격부하시 반응의 비교)

  • Ahn, Mee-Kyung;Lee, Kyu-Hoon
    • Journal of Environmental Science International
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    • v.3 no.3
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    • pp.285-296
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    • 1994
  • The objective of this study was to examine and compare to transient response to quantitative and hydraulic shocks which produce equal changes in mass rate of organic feed in aerobic fixed-film process. The general experimental approach was to operate the system at several growth rates under steady-state(pre-shock) conditions, then to apply step changes during day 3 in dilution rate(hydraulic shock) , or feed concentration(Quantitative shock) at the same organic mass loading rate. Performance was assessed in both the transient state and the new steady-state (post- shock). Shock load of different type did not produced equivalent disruptions of effluent quality for equal increases in mass loading rate. Based on effluent concentrations, a hydraulic and a Quantitative shock at the same mass loading caused equal increase in total effluent COD, but the increase was primarily a result of suspended solids the hydraulic shock and COD in the quantitative shock. The time which effluent COD came to peak values were about 32~48 hours at the low organic loads and 52 ~ 72 hours at the high organic loads, respectively A quantitative shock produced a much greater increase in effluent COD than did a hydraulic shock at the same mass loading. Mean and peak values of effluent concentration weve increased in 2.8~4.2 times at low organic loading rate, 5.2~6.6 times at the high organic loading rate, respectively. Key words : Aerobic fixed-film reactor, Quantitative shock, hydraulic shock, mass loading rate.

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PMS EVOLUTION MODEL GRIDS AND THE INITIAL MASS FUNCTION

  • PARK BYEONG-GON;SUNG HWANKYUNG;KANG YONG HEE
    • Journal of The Korean Astronomical Society
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    • v.35 no.4
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    • pp.197-208
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    • 2002
  • Five contemporary pre-main sequence (PMS) evolution model grids are compared with the photo-metric data for a nearly complete sample of low-mass members in NGC 2264. From amongst the grids compared, the models of Baraffe et al. (1998) prove to be the most reliable in mass-age distribution. To overcome the limited mass range of the models of Baraffe et al. we derived a simple transformation relation between the mass of a PMS star from Swenson et al. (1994) and that from Baraffe et al., and applied it to the PMS stars in NGC 2264 and the Orion nebula cluster (ONC). The resulting initial mass function (IMF) of the ONC shows that the previous interpretation of the IMF is not a real feature, but an artifact caused by the evolution models adopted. The IMFs of both clusters are in a good agreement with the IMF of the field stars in the solar neighborhood. This result supports the idea proposed by Lada, Strom, & Myers (1993) that the field stars originate from the stars that are formed in clusters and spread out as a result of dynamical dissociation. Nevertheless, the IMFs of OB associations and young open clusters show diverse behavior. For the low-mass regime, the current observations suffer from difficulties in membership assignment and sample incompleteness. From this, we conclude that a more thorough study of young open clusters is necessary in order to make any definite conclusions on the existence of a universal IMF.

The Effects of Skeletal Muscle Mass and Muscle Fatigue on the Proprioceptive Position Sense of the Knee Joint (뼈대근육량과 근피로가 무릎관절 고유수용성 위치감각에 미치는 영향)

  • Park, Sookyoung;Park, Kanghui
    • Journal of The Korean Society of Integrative Medicine
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    • v.8 no.2
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    • pp.139-147
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    • 2020
  • Purpose : Proprioceptive position sense plays a key role in providing joint stability, and multiple factors are related to proprioceptive position sense. Thus, this study aimed to determine the effects of body composition, particularly skeletal muscle mass on proprioceptive position sense following muscle fatigue. Methods : Healthy female subjects agreed to have their body composition analyzed. Only subjects who had 18.5-22.9 kg/㎡ of BMI (body mass index) were included in this study, and the participants were divided into two groups by skeletal muscle mass level. The experimental group had a level of skeletal muscle lower than the standard level (n=9), while the control group showed a standard or high level of skeletal muscle mass (n=11). To determine the change in proprioceptive position sense of the knee joint, the absolute angle error (AAE) was evaluated following muscle fatigue on low extremity. The muscle fatigue was induced by isokinetic resistance exercise program of Biodex system. AAE was measured by the Biodex system and compared the result before and after muscle fatigue. Results : The experimental group showed a significant AAE difference between before (3.16±2.48 °) and after (5.40±2.61 °) muscle fatigue. In addition, there was a AAE difference between the experimental (5.40±2.61 °) and control groups (3.53±1.67 °) after fatigue; however, there was no significance. Those results indicated that low level of skeletal muscle mass might influence the proprioceptive position sense of the knee joint after muscle fatigue. Conclusion : Thus, maintaining the proper level of skeletal muscle mass is pivotal to reduce the risk of injury following muscle fatigue in ADL or sport activities.

Simulation Injection Mass with Variable Injection Condition in GDI Engine using AMESim (AMESim을 이용한, GDI 엔진에서 연료의 분사조건 변화에 따른 분사량 변화 예측)

  • Shin, Suk Shin;Song, Jingeun;Park, Jongho
    • Journal of ILASS-Korea
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    • v.18 no.1
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    • pp.61-65
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    • 2013
  • In case of GDI engine, shape of injected fuel and injection mass are one of the most important factors for good fuel efficiency and power. But it should be too inefficient and difficult to acquire injection mass data by experiment because condition in engine vary with temperature, pressure, and so on. So, this paper suggests the AMESim (Advanced Modeling Environment for Simulation of Engineering Systems) as simulation program to calculate injection mass. For both simulation and experiment, n-heptane is used as fuel. In AMESim, I modeled the GDI injector and simulated several cases. In experiment, I acquired the injection mass using Bosch method to apply ambient pressure. The AMESim show reasonable result in comparison with experimental data especially at injection pressure 15 MPa. Other conditions are also in good accord with experimental data but error is a little bit large because the injection mass is so low.

Distribution of Baryonic Matter in Dark Matter Halos: Effect of Dynamical Friction

  • Bae, Yeong-Bok;Lee, Hyung-Mok
    • The Bulletin of The Korean Astronomical Society
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    • v.36 no.1
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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 $10^5M_{\bigodot}$.

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