• 천문학회보
• /
• 제42권1호
• /
• pp.49.1-49.1
• /
• 2017

In order to investigate the origin of multiple stellar populations in the halo and bulge of the Milky Way, we have constructed chemical evolution models for the low-mass proto-Galactic subsystems such as globular clusters (GCs). Unlike previous studies, we assume that supernova blast waves undergo blowout without expelling the pre-enriched gas, while relatively slow winds of massive stars, together with the winds and ejecta from low and intermediate mass asymptotic giant branch stars, are all locally retained in these less massive systems. We first applied these models to investigate the origin of super-helium-rich red clump stars in the metal-rich bulge as recently suggested by Lee et al. (2015). We find that chemical enrichments by the winds of massive stars can naturally reproduce the required helium enhancement (dY/dZ = 6) for the second generation stars. Disruption of these "building blocks" in a hierarchical merging paradigm would have provided helium enhanced stars to the bulge field. Interestingly, we also find that the observed Na-O anticorrelation in metal-poor GCs can be reproduced, when multiple episodes of starbursts are allowed to continue in these subsystems. Specific star formation history with decreasing time intervals between the stellar generations, however, is required to obtain this result, as would be expected from the orbital evolution of these subsystems in a proto-Galaxy. The "mass budget problem" is also much alleviated by our models without ad-hoc assumptions on star formation efficiency and initial mass function.

• Journal of Welding and Joining
• /
• 제26권6호
• /
• pp.67-73
• /
• 2008

Three-dimensional transient simulation of laser-GMA hybrid welding involving multiple physical phenomena is conducted neglecting the interaction effect of laser and arc heat sources. To reproduce the bubble and pore formations in welding process, a new bubble model is suggested and added to the established laser and arc welding models comprehending VOF, Gaussian laser and arc heat source, recoil pressure, arc pressure, electromagnetic force, surface tension, multiple reflection and Fresnel reflection models. Based on the models mentioned above, simulations of laser-GMA hybrid butt welding are carried out and besides the molten pool flow, top and back bead formations could be observed. In addition, the laser induced keyhole formation and bubble generation duo to keyhole collapse are investigated. The bubbles are ejected from the molten pool through its top and bottom regions. However, some of those are entrapped by solid-liquid interface and remained as pores. Those bubbles and pores are intensively generated when the absorption of laser power is largely reduced and consequently the full penetration changes to the partial penetration.

• Asian Pacific Journal of Cancer Prevention
• /
• 제15권11호
• /
• pp.4527-4533
• /
• 2014

Background: This descriptive and cross-sectional study aimed to investigate effects of cigarette smoking across three generations and perceptions of the smoking-cancer relationship on the cigarette smoking status of Turkish university students. Materials and Methods: The study sample comprised of 434 university students studying in different departments of a university. Data were collected using a socio-demographic data collection form and the Decisional Balance Scaleqand evaluated using the Mann-Whitney U test, CHAID and multiple regression analyses. Results: The average age of the students participating in the study is 19.6+.5.0, some 11.3% of the students reporting that they smoked cigarettes. No statistically significant relationship was ascertained between the cigarette smoking statuses of the students based on the cigarette smoking status of their grandparents (p=0.144). but there was alink to that of their parents (p=0.002). The difference between the cigarette smoking ratios of the students based on their perceptions of smoking-cancer relationship was statistically significant (p<0.001). Believing that there is a relationship between smoking and cancer decreased likelihood of cigarette smoking 3.7 fold. Cigarette smoking by grandparents, and believing that there is a relationship between smoking and cancer, and cigarette smoking by parents explained 8.3% of the cigarette smoking status of the students. Conclusions: While cigarette smoking by grandparents only indirectly influences cigarette smoking by the students, believing that there is a relationship between smoking and cancer, and cigarette smoking by parents are influential variables in determining cigarette smoking by Turkish students.

• 복식문화연구
• /
• 제27권5호
• /
• pp.461-478
• /
• 2019

As the concept of "marriage age" gradually disappears, the consumption class of the wedding market includes not only X and Y generations but also Z generations, and each generation has its own characteristics as it is already known, and there are differences in the consumption. So this research analyzed age-related behavior differences in both awareness of and preparation for marriage. Three hundred sixteen unmarried Korean males and females comprised the study population and data was collected from March 5, 2019, to April 3, 2019. The SPSS Statistics 23.0 Package was used for analysis, specifically the functions of frequency, cross tabulation, factor analysis, chi-squared test, Cronbach's alpha, Duncans's new multiple range test (MRT), and analysis of variance (ANOVA). Marriage motivation was analyzed by three factors, and there were significant differences in two types. Marital involvement was analyzed by two factors, and both factors showed significant age-related differences. Concerns relating to marriage preparation were analyzed by four factors, and two varied according to respondent age. Regarding marriage preparation behaviors, the analysis revealed that the marriage preparation method appreciably differed between age groups. Our analysis also found significant age-related differences in "the main media usually used to acquire information" and "the paths preferred for acquiring information in preparing for marriage". We expect that study results will be useful for identifying new research directions, understanding the dimensions of the wedding industry, and developing related marketing strategies.

• 디지털융복합연구
• /
• 제19권1호
• /
• pp.217-228
• /
• 2021

본 연구는 간호사 세대별 삶에 대한 가치관의 차이를 확인하고, 간호사 세대별 이직의도에 미치는 영향을 확인하기 위해 실시되었다. X-세대, Y-세대, Z-세대 간호사 294명이 연구에 참여하였고, 간호사 세대별 가치관의 차이와 이직의도에 미치는 영향을 확인하기 위하여 일원배치분산분석(ANOVA)과 다중회귀분석을 실시하였다. 연구결과, X-세대와 Y-세대 간호사들은 삶에서 가족생활을 가장 중요한 것으로 생각하였고, 그 다음으로 X-세대는 일을, Y-세대 간호사는 여가시간을 중요한 요인으로 생각하였다. 반면, Z-세대 간호사들은 삶에서 여가시간을 가장 중요한 요인으로 고려하였다. X-세대와 Y-세대 간호사들은 직업생활에서 우울과 심리적 부담감이, Z-세대 간호사는 일을 중요하게 생각하는 요인이 이직의도에 가장 많은 영향을 미치는 것으로 나타났다. 본 연구는 각 간호사 세대별 이직의도에 미치는 영향요인이 다름을 확인하였고, 이러한 결과는 다양한 세대가 함께 일하는 간호조직에서 효과적인 인적자원관리를 위한 정책개발에 필요한 기초자료를 제공함에 그 의의가 있다.

• Asian-Australasian Journal of Animal Sciences
• /
• 제14권11호
• /
• pp.1505-1510
• /
• 2001

A method for mapping quantitative trait loci (QTL) was introduced incorporating the information of mixed progeny from complex pedigrees. The method consisted of two steps based on single marker analysis. The first step was to examine the marker-trait association with a mixed model considering common environmental effect and reversed QTL-marker linkage phase. The second step was to estimate QTL effects by a weighted least square analysis. A simulation study indicated that the method incorporating mixed progeny from multiple generations improved the accuracy of QTL detection. The influence of within-genotype variance and recombination rate on QTL analysis was further examined. Detecting a QTL with a large within-genotype variance was more difficult than with a small within-genotype variance. Most of the significant marker-QTL association was detectable when the recombination rate was less than 15%.

• 한국주조공학회지
• /
• 제24권2호
• /
• pp.63-70
• /
• 2004

Foundry techniquews for large steel casting depends on the skills of foundrymen considerably. Especially, the problem of reducing casring surface defects is difficult to clear numerically. Statistical analysis by using wuantification theory for hot tear and sand inclusion, and multiple regression analysis for dimensional defects have been shown to be examples of solving this difficulty. Many causes of surface defects can be evaluated by these analyses. These evaluations serve as the base data of defect reduction and contribute to the constant improvement of casting quality and quality enhancement activity. The system to perform quality enhancement activity was developed and it proved very useful for transfering foundry techniques and skills from the old to young generations.

• 가정과삶의질연구
• /
• 제29권3호
• /
• pp.85-97
• /
• 2011

The main purpose of this study was to examine the relationship between parenting styles between generations and the comparative effects of grandfathers' and grandmothers' parenting styles on the parenting styles of parents. The subjects were 299 mothers and fathers of children aged between 2 and 5 years old who attend 9 preschools in Seoul. Data were analyzed by Pearson's correlation coefficients and multiple regressions. The results show that a strong relationship exists between grandparents' parenting styles and the parenting styles of parents as grandparents' parenting styles predict parents' positive and negative parenting styles. It was also found that the influence of grandmothers' parenting styles on the parenting styles of mothers is stronger than that of grandfathers' parenting styles, but less influence of grandfathers' parenting styles on fathers' parenting styles exists.

• 대한전기학회논문지:전력기술부문A
• /
• 제48권8호
• /
• pp.958-964
• /
• 1999

The distance in load parameter space to the closest saddle node bifurcation (CSNB) point provides the worst case power margin to voltage instability and the left eigenvector at CSNB identifies the most effective direction to steer the system to maximize voltage stability under contingency. This paper presents an improved direct method for computing CSNB: the order of nonlinear systems equations is reduced to about twice of the size of load flow equations in contrast to about three-times in Dobson's direct method; the initial guess for the direct method is computed efficiently and robustly by combined use of continuation power flow, a pair of multiple load flow solution with Lagrange interpolation. It is also shown that voltage stability may be enhanced significantly with shift of generations in the direction of the left eigenvector at CSNB.

• 전력전자학회:학술대회논문집
• /
• 전력전자학회 2008년도 추계학술대회 논문집
• /
• pp.36-38
• /
• 2008

본 논문에서는 여러 대의 인버터를 동시에 사용하는 분산전원 환경하에서 Anti-islanding을 효과적으로 할 수 있는 방안을 제안한다. 제안하는 Anti-islanding기법은 SMS(Sliding Mode Frequency Shift)를 근간으로 하면서 공진 Q가 높을 때 검출이 어려운 단점을 해결하는 방법을 제시한다. SMS위상의 변동 값을 판단근거를 사용하지 않고 SMS위상의 적분 값을 판단근거로 사용한다. Run on시간이 0.5초 이내로 국내외 규격을 모두 만족시킨다. 여러 대의 인버터를 병렬로 접속해도 islanding 검출이 탁월하다. 출력전력의 품질 면에 있어서도 다른 Anti-islanding기법에 비해 우수하다. 본 알고리즘의 우수성을 시뮬레이션과 실험을 통해 검증하였다.