• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 1997년도 춘계학술대회 논문집
• /
• pp.481-485
• /
• 1997

6063-T5 alloys are tested in laboratory air, water and 3% NaCl solution to investigate the effects of corrosive environment on the retardation behavior through single overload fatigue test. Also, the fatigue crack propagation and the crack closure behavior are studied. The results obtained in this experimental study are summarized as follows: 1) Behaviors of fatigue crack growth retardation are observed in water and 3% NaCl solution as they do in air. The number of delay cycles and the size of affected region by single overload decrease greatly in water and 3% NaCl compared with those in air. 2) In fractographic results, the overload marking by single overload appear remarkably in air, but indistinctly in water and 3% NaCl solution. 3) The effect of crack closure on crack propagation is most remarkable in the beginning of crack propagation. With crack propagation, the crack closure level and its effect decrease greatly.

• 동아시아식생활학회지
• /
• 제25권1호
• /
• pp.73-86
• /
• 2015

The present study was performed to evaluate food behavior and nutritional status of children in a community child center using nutrition quotient according to age and growth index of children. The number of subjects enrolled in this study was 152 including 73 boys and 79 girls. Participants consisted of children from 5 to 12 years old, who visited a community child center in the area. Growth index was assessed through body mass index by height and weight and examined according to age. Subjects were divided into underweight, normal weight, overweight and obese according to questionnaire, which consisted of five categories including balance, diversity, moderation, regularity and practice, were analyzed by SPSS statistical program. Current results show significant differences in the diversity and regularity (p<0.05, p<0.001, respectively). Additionally, four items in the form of 10 questions showed significant differences related to habits of sodium-related food intake. This study design will be a useful tool in the evaluation of food behavior and nutritional status of preschoolers or elementary school children in community child centers, together with food frequency questionnaires related with sodium food intake.

• 대한용접접합학회:학술대회논문집
• /
• 대한용접접합학회 2007년 추계학술발표대회 개요집
• /
• pp.235-237
• /
• 2007

In this paper, fabrication of Sn-3.0Ag-0.5Cu solder bumping having accurate composition and behavior of intermetallic compounds(IMCs) growth at interface between Sn-Ag-Cu bumps and Cu substrate were studied. The ternary alloy of the Sn-3.0Ag-0.5Cu solder was made by two binary(Sn-Cu, Sn-Ag) electroplating on Cu pad. For the manufacturing of the micro-bumps, photo-lithography and reflow process were carried out. After reflow process, the micro-bumps were aged at $150^{\circ}C$ during 1 hr to 500 hrs to observe behavior of IMCs growth at interface. As a different of Cu contents(0.5 or 2wt%) at Sn-Cu layer, behavior of IMCs was estimated. The interface were observed by FE-SEM and TEM for estimating of their each IMCs volume ratio and crystallographic-structure, respectively. From the results, it was found that the thickness of $Cu_3Sn$ layer formed at Sn-2.0Cu was thinner than the thickness of that layer be formed Sn-0.5Cu. After aging treatment $Cu_3Sn$ was formed at Sn-0.5Cu layer far thinner.

• 한국진공학회:학술대회논문집
• /
• 한국진공학회 2012년도 제42회 동계 정기 학술대회 초록집
• /
• pp.573-573
• /
• 2012

High quality $VO_2$ thin films were successfully grown on GaN substrate by optimizing oxygen partial pressure during the growth using RF sputtering technique. The $VO_2$ thin film grown on GaN substrate exhibited an unusual metal insulator transition behavior, which was known to be observed only either in doped sample or under uniaxial stress. Raman spectra also confirmed that metal insulator transition occurred from monoclinic M1 to rutile R phase via monoclinic M2 phase with increasing temperature. We believe that large lattice mismatch between $VO_2$ and GaN substrate may cause M2 phase to be thermodynamically stable. Optical transmittance and its electrical switching behavior were carefully investigated to elucidate the underlying physics of its metal insulator transition behavior. This study may lead to a unique opportunity to better understand the growth mechanism of M2 phase dominant $VO_2$ thin films.

• Child Health Nursing Research
• /
• 제19권2호
• /
• pp.69-75
• /
• 2013

The significance of father's parenting has been considered as a critical factor in facilitating growth and development and in promoting wellbeing of children. Pediatric nursing is a pertinent science to develop parenting roles, because it deals with knowledge and skills on growth and development and health of child. For this paper current studies were reviewed related to consequences to the family, content and factors influencing paternal parenting, and father's reactions to child rearing participation. Perspectives of future studies in pediatric nursing are summarized as follows. First, paternal parenting has to be studied more actively to contribute to family health and to meet the academic responsibility of pediatric nursing. Second, it is necessary to study the consequences to child's health and health behavior of paternal parenting. Also it is necessary to be concerned about fathers' reactions, like stress in parenting behavior, to understand the parenting father himself. Third, an objective measure of caregiving behavior (not self-reporting) is needed to determine whether the father is behaving appropriately. Further, experimental research has to be implemented to develop intervention programs for paternal parenting. It is hoped that the examination of these studies leads to develop of knowledge and practice in paternal parenting.

• 폴리머
• /
• 제31권5호
• /
• pp.385-392
• /
• 2007

Poly (N-vinylpyrrolidone) (PVP) groups were grafted onto a poly(3-hydroxybutyrate-co-3-hydroryvalerate) (PHBV) backbone in order to modify its properties and synthesize a novel biocompatible copolymer. The crystallization behavior of PHBV and grafted PHBV was investigated by differential scanning calorimetry (DSC) and polarized optical microscopy (POM). During the cooling-induced crystallization process, the crystallization temperature and the crystallization rate of the grafted PHBV decreased with increasing PVP weight fraction. On the heating scans of all grafted PHBV samples, a new crystallization exothermic peak appeared at almost the same temperature, suggesting the operation of a recrystallization process, while the melting temperature ($T_m$) and the apparent enthalpy of fusion (${\Delta}H_f$) were not affected by graft modification. During the isothermal crystallization process at the same temperature, the presence of side PVP groups decreased the spherulitic growth rate and the spherulitic band spacing with increasing PVP weight fraction in samples.

• 콘크리트학회지
• /
• 제8권6호
• /
• pp.205-212
• /
• 1996

본 논문은 경계요소법에 의한 콘크리트의 진행성 파괴해석과 연화거동 해석시 발생하는 불안정 거동을 규명하는 연구이다. 파괴가 일어나는 콘크리트에 작용하는 최대하중을 구하고 콘크리트의 균열 성장에 따른 비선형거동을 예측하기 위하여 균열선단의 브리징 영역에 Dugdale-Barenblatt형 모델을 사용하였으며, 브리징 영역의 인장연화 상태를 선형인장연화 곡선을 사용하여 모델링하였다. 경계요소법을 사용하였으며 콘크리트의 파괴진행을 해석하기 위하여 변위 및 표면력 경계적분방정식으로부터 균열을 포함한 연속체의 균열 경계적분방정식을 정식화하였으며, 콘크리트 보와 인장시편에 대하여 진행성 파괴해석을 실시하였다. 또한 콘크리트의 진행성 파괴해석에 자유응력균열의 성장 및 진행을 고려하지 않음으로서 발생하는 불안정 연화거동을 제거하는 수치해석기법을 제시하였다.

• 한국재료학회지
• /
• 제9권6호
• /
• pp.609-614
• /
• 1999

The effect of the amount of $SiO_2$dopant on the behavior of $AlO_2$$O_3$-composite formation by melt oxdation of Al-alloy was examined in this paper. The $SiO_2$powder was spread on the top surface of the Al-1Mg-3-Si-5Zn-1Cu alloy in th alumina crucible. The selected amount of each powder was 0.03, 0.10, 0.16g/$\textrm{cm}^2$. The oxidation behavior was determined by observing the weight gain after the heat treatment for 10 hours at 1373K. The macroscopic structure of formed oxide layer was examined by an optical microscope. The top surface and the cross-section of the grown oxide layer were investigated by SEM and analysed by EDX. The $SiO_2$ powder was determined to enhance oxidation by thermit reaction with Al which reduced the growth incubation period of the oxidation layer. As the amount of the $SiO_2$dopant increased, the growth rate decreased due to the precipitated Si which blocked the Al-alloy channel in the composite materials. However, more uniform layer was obtained due to the occurrance of the enhanced oxidation reaction in the whole alloy surface compared to the case of addition of less amount of dopant.

• 한국표면공학회지
• /
• 제47권6호
• /
• pp.293-296
• /
• 2014

Fe-Ni has been of great interest because it is known as one of low thermal expansion alloys as various application areas. This alloy was fabricated by electroforming process, and effect of heat treatment on thermal expansion and hardness was investigated. Nano-crystalline structure of 13.3 - 63.5 nm in size was observed in the as-deposited alloy. To investigate the effect of heat treatment on grain growth and mechanical/thermal properties, we conducted hardness and coefficient of thermal expansion (CTE). From this, we confirmed these properties were varied by heat treatment. In this nano-crystalline alloy, we could observe abnormal behavior in thermal expansion between $350-400^{\circ}C$. Additionally, an abrupt change in hardness has also been observed. However, once the grains grow up to micro-sized the mechanical and thermal properties mentioned above were stabilized similar to those of bulk alloys due to heat treatment.

• The Journal of Asian Finance, Economics and Business
• /
• 제8권4호
• /
• pp.897-907
• /
• 2021

The purpose of this study is to investigate the quality of entrepreneurship - motivation, entrepreneurial orientation, and risk behavior - in relation to the odds of micro-, small- and medium-sized enterprises' (MSMEs) financial performance in Indonesia. Additionally, this paper investigates how these qualities apply for the current challenges perceived by MSMEs' entrepreneurs in Indonesia due to Covid-19 crisis; specifically, this paper examines the odds of MSMEs' financial performance during the pandemic in respect to when these qualities are implemented by the entrepreneurs. The empirical data was obtained from an online survey by means of a structured questionnaire. MSMEs surveyed were randomly selected on a national scale. To test the hypotheses, a quantitative approach is employed, using multinomial regression. The main result shows that, under normal economic environment, the more intrinsically-motivated and continuity-driven entrepreneur is, the more likely the MSME will achieve financial growth compared to remaining stagnant. To our surprise, innovativeness leads to less likelihood of MSME's financial growth, suggesting the significance of innovation does not apply to MSMEs in Indonesia. Lastly, MSMEs' risk behavior to operate in a stable business environment is found more likely to result in a better performance and is true for operational and financial risks, but not marketing risks.