• Tribology and Lubricants
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• 제35권3호
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• pp.158-168
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• 2019

This paper presents the investigation of two types of rotordynamic modeling issues for 2.2 kW-class, rated speed of 1,800 rpm, squirrel-cage type induction motors. These issues include the lamination structure of rotor cores, and the radial clearance of ball bearings that support the shaft of the motor. Firstly, we focus on identifying the effects of rotor core lamination on the rotordynamic analysis via a 2D prediction model. The influence of lamination is considered as the change in the elastic modulus of the rotor core, which is determined by a modification factor ranging from 0 to 1.0. The analysis results show that the unbalanced response of the rotor-bearing system significantly varies depending on the value of the modification factor. Through modal testing of the system, the modification factor of 0.079 is proven to be appropriate to consider the effects of lamination. Next, we investigate the influence of ball bearing clearance on the rotordynamic analysis by establishing a bearing analysis model based on Hertz's contact theory. The analysis results indicate that negative clearance greatly changes the bearing static behavior. Rotordynamic analysis using predicted bearing stiffness with various clearances from -0.005 mm to 0.010 mm reveals that variations in clearance result in a slight difference in the displacement of the system up to 18.18. Thus, considering lamination in rotordynamic analysis is necessary as it can cause serious analysis errors in unbalanced response. However, considering the effect of the bearing clearance is optional because of its relatively weak impact.

• 한국의류학회지
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• 제13권1호
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• pp.79-87
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• 1989

In the part 1 and 2, relations were found between fundmental mechanical properties and primary hand values, performance of Korean women's summer and fall & winter fabrics. In this paper, in order to investigate the hand values and mechanical properties such as tensile, shearing, bending, compression, surface and thickness & weight of the core-spun yarn woven fabrics for Korean folk clothes were measured by KES-F system. The experimental results are statistically analyzed in the aspects of the mechanical properties, their effects on the hand values, formation of weared clothes and transformation behavior. The correlation in the hand values are analyzed, too. Furthermore, there mechanical properties are discussed in comparison with those values for kimono fabrics. The main results are summarized as follows: 1. The core-spun yarn woven fabrics for Korean folk clothes have box-shaped silhouette based on higher bending rigidity and shear elasticity. 2. The core-spun yarn woven fabrics for Korean folk clothes are inferior to silk fabrics, superior to polyester fabrics in formation. 3. A drapability and wrinkle recovery of core-spun yarn woven fabrics for Korean folk clothes formation for weared clothes are inferior to polyester fabrics, superior to silk fabrics. 4. A primary factor of mechanical properties contribute to the hand values of core-spun yarn woven fabrics for Korean folk clothes are same as the Korean women's winter fabrics, except for flexibility with soft feeling. 5. As for the hand values of core-spun yarn woven fabrics for Korean folk clothes, stiffness, anti-drape stiffness are superior to those of polyester fabrics. And also, flexibility with soft feeling, scrooping feeling of core-spun yarn woven fabrics have greater values as compared with silk fabrics for Korean folk clothes.

• Journal of Applied Biological Chemistry
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• 제50권3호
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• pp.109-114
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• 2007

Sar1p is a ras-related GTP-binding protein that functions in intracellular protein transport between the endoplasmic reticulum (ER) and the Golgi complex. The effector domain of Ras family proteins is highly conserved and this domain is functionally interchangeable in plant, yeast and mammalian Sar1. Using a recombinant Brassica sar1 protein (Bsar1p) harboring point mutations in its effector domain, we here investigated the ability of Sar1p to bind and hydrolyze GTP and to interact with the two sar1-specific regulators, GTPase activating protein (GAP) and guanine exchange factor (GEF). The T51A and T55A mutations impaired Bsar1p intrinsic GTP-binding and GDP-dissociation activity. In contrast, mutations in the switch domain of Bsar1 did not affect its intrinsic GTPase activity. Moreover, the P50A, P54A, and S56A mutations affected the interaction between Bsar1p and GAP. P54A mutant protein did not interact with two regulating proteins, GEF and GAP, even though the mutation didn't affect the intrinsic GTP-binding, nucleotide exchange or GTPase activity of Bsar1p.

• 문화기술의 융합
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• 제6권2호
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• pp.199-205
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• 2020

연구 목적은 간호대학생의 재난간호교육 요구도와 재난간호지식, 재난준비도, 자기효능감, 재난간호 핵심역량의 관계 및 영향 요인을 파악하기 위해 일 지역 간호대학생 144명을 대상으로 자료를 수집하였다. 자료분석은 기술통계분석, 상관분석, 다중 회귀분석 등을 실시하였다. 연구결과 재난간호교육 방법 요구도에서는 시뮬레이션 실습수업이 가장 높게 나타났다. 재난간호 핵심역량은 재난준비도, 자기효능감, 재난간호지식과 유의한 정적 상관관계가 있음을 나타냈다. 간호대학생의 재난간호 핵심역량 영향요인으로는 학년(β=.343), 자기효능감(β=.329), 재난준비도(β=.282), 응급실 실습경험(β=.159)순으로 확인되었으며, 이는 53.2 %의 설명력을 보여주었다. 따라서 재난간호 핵심역량 영향요인 및 재난간호교육 요구도를 바탕으로 간호대학생의 재난 발생 시 대처능력을 향상 시킬 수 있는 맞춤형 재난교육프로그램 개발과 지원이 필요하다.

• Nuclear Engineering and Technology
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• 제37권1호
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• pp.91-100
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• 2005

Kyung-hee Thorium Fuel (KTF), a heterogeneous thorium-based seed and blanket design concept for pressurized light water reactors, is being studied as an alternative to enhance proliferation resistance and fuel cycle economics of PWRs. The proliferation resistance characteristics of the KTF assembly design were evaluated through parametric studies using neutronic performance indices such as Bare Critical Mass (BCM), Spontaneous Neutron Source rate (SNS), Thermal Generation rate (TG), and Radio-Toxicity. Also, Fissile Economic Index (FEI), a new index for gauging fuel cycle economy, was suggested and applied to optimize the KTF design. A core loaded with optimized KTF assemblies with a seed-to-blanket ratio of 1: 1 was tested at the Korea Next Generation Reactor (KNGR), ARP-1400. Core design characteristics for cycle length, power distribution, and power peaking were evaluated by HELIOS and MASTER code systems for nine reload cycles. The core calculation results show that the KTF assembly design has nearly the same neutronic performance as those of a conventional $UO_2$ fuel assembly. However, the power peaking factor is relatively higher than that of conventional PWRs as the maximum Fq is 2.69 at the M$9^{th}$ equilibrium cycle while the design limit is 2.58. In order to assess the economic potential of a heterogeneous thorium fuel core, the front-end fuel cycle costs as well as the spent fuel disposal costs were compared with those of a reference PWR fueled with $UO_2$. In the case of comprising back-end fuel cycle cost, the fuel cycle cost of APR-1400 with a KTF assembly is 4.99 mills/KWe-yr, which is lower than that (5.23 mills/KWe-yr) of a conventional PWR. Proliferation resistance potential, BCM, SNS, and TG of a heterogeneous thorium-fueled core are much higher than those of the $UO_2$ core. The once-through fuel cycle application of heterogeneous thorium fuel assemblies demonstrated good competitiveness relative to $UO_2$ in terms of economics.

• 직업교육연구
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• 제37권2호
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• pp.1-18
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• 2018

4차 산업혁명의 가속화로 인하여 노동시장에서는 전공실무능력과 더불어 빠른 기술의 변화에 능동적이고 적극적으로 대처할 수 있는 직업기초능력을 갖춘 인재가 중요해지고 있다. 이에 따라 4년제 대학생의 직업기초능력 진단과 배양에 대한 필요성이 증가하였음에도 불구하고, NCS 직업기초능력을 포함한 여러 직업기초능력으로 4년제 대학생의 직업기초능력을 정의하고 진단하기에는 일부 한계가 존재한다. 따라서 본 연구에서는 4년제 대학생을 위한 NCS 직업기초능력에 대한 재정의 및 K대학교의 재학생 498명을 대상으로 실시한 설문조사 결과를 바탕으로 요인분석을 실시하여 진단문항을 개발하였다. 연구결과, 첫째, 자기개발능력은 학업관리와 실행, 자기개발개념이해와 설명, 긍정적 자기인식, 책임감과 소명의식, 체력관리, 자기관리개념이해와 설명으로 하위영역을 구분하고, 진단문항을 도출하였다. 둘째, 조직이해능력은 조직환경이해, 조직내부이해, 조직구조이해, 업무이해, 국제감각으로 하위영역을 구분하고, 진단문항을 도출하였다. 셋째, 자원관리능력은 시간관리이해, 시간관리실행, 물적자원관리, 인적자원관리로 하위영역을 구분하고, 진단문항을 도출하였다. 이러한 연구 결과를 토대로 제언 및 시사점을 도출하였다.

• Nuclear Engineering and Technology
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• 제21권4호
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• pp.294-301
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• 1989

상하부 2개의 노외계측기, 노입구관 온도 및 제어봉 위치 신호를 이용하여 상세한 축방향 출력분포를 계산할 수 있는 APDMS프로그램을 개발하였다. 상하부 2개의 노외계측기 신호가 제어봉 위치에 의하여 결정된 제어봉 간섭계수와 노입구관 온도에 따른 온도 간섭계수에 대하여 보정된 후 노심 주변출력을 얻기 위하여 보정된 노외계측기 신호에 shape annealing matrix가 적용되었다. 노심의 상하부 경계에서의 출력을 얻기 위해서는 평균 노심출력과 주변출력과의 선형적 관계를 이용한 노심 상하부의 평균출력에 경계점 출력보정계수가 적용되었다. 축방향 출력분포가 2개의 노외계측기에 의해 계산된 상하부 평균 노심출력, 상하부 경계면에서의 출력 및 미리 계산된 노심의 중심 위치에서의 출력을 이용하여 spline approximation에 의하여 계산되었다. 연소도, 출력준위, 제어봉 위치 및 axial offset의 변화에도 불구하고 고리 3호기 4주기에 대하여 BOXER 코드와 APDMS 프로그램에 의해 계산된 축방향 출력분포의 비교는 5% root mean square 오차내에서 일치함을 보여 주었다.

• 한국조리학회지
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• 제17권4호
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• pp.219-237
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• 2011

본 연구의 목적은 국내 외식업계의 비정규직 직원을 대상으로 핵심자기평가, 일-가족 지원, 직장만족 그리고 이직의도의 관계를 분석함으로써 직원의 이직을 줄이기 위한 방안을 모색하고 추후 이와 관련된 연구의 방향을 제시하는 것이다. 본 연구의 가설을 검증하기 위하여 AMOS 4.0과 SPSS 10.0 통계 프로그램을 이용하였으며, 분석 방법은 신뢰도분석(reliability analysis), 빈도분석(frequency analysis), 확인적 요인분석(confirmatory factor analysis), 상관관계 분석(correlation analysis) 그리고 공분산 구조분석(covariance structure analysis)을 실시하였다. 연구 결과, 핵심자기평가는 일-가족 방향 지원과 가족-일 방향 지원 모두에 긍정적인 영향이 있는 것으로 밝혀졌다. 일-가족 지원과 직장만족의 관계에 있어서는 가족-일 방향 지원만이 직장만족에 긍정적인 영향이 있는 것으로 나타났다. 마지막으로 직장만족은 직원의 이직을 줄이는 것에 효과가 있는 것으로 규명되었다.

• Journal of Ginseng Research
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• 제43권3호
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• pp.421-430
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• 2019

Background: The ginsenoside Rg3, one of active components of red ginseng, has chemopreventive and anticancer potential. Cancer stem cells retain self-renewal properties which account for cancer recurrence and resistance to anticancer therapy. In our present study, we investigated whether the standardized Korean Red Ginseng extract (RGE) and Rg3 could modulate the manifestation of breast cancer stem cell-like features through regulation of self-renewal activity. Methods: The effects of RGE and Rg3 on the proportion of $CD44^{high}/CD24^{low}$ cells, as representative characteristics of stem-like breast cancer cells, were determined by flow cytometry. The mammosphere formation assay was performed to assess self-renewal capacities of breast cancer cells. Aldehyde dehydrogenase activity of MCF-7 mammospheres was measured by the ALDEFLUOR assay. The expression levels of Sox-2, Bmi-1, and P-Akt and the nuclear localization of hypoxia inducible $factor-1{\alpha}$ in MCF-7 mammospheres were verified by immunoblot analysis. Results: Both RGE and Rg3 decreased the viability of breast cancer cells and significantly reduced the populations of $CD44^{high}/CD24^{low}$ in MDA-MB-231 cells. RGE and Rg3 treatment attenuated the expression of Sox-2 and Bmi-1 by inhibiting the nuclear localization of hypoxia inducible $factor-1{\alpha}$ in MCF-7 mammospheres. Suppression of the manifestation of breast cancer stem cell-like properties by Rg3 was mediated through the blockade of Akt-mediated self-renewal signaling. Conclusion: This study suggests that Rg3 has a therapeutic potential targeting breast cancer stem cells.

• Bulletin of the Korean Chemical Society
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• 제31권6호
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• pp.1519-1526
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• 2010

The behavior of peptide or protein solutes in saline aqueous solution is a fundamental topic in physical chemistry. Addition of ions can strongly alter the thermodynamic and physical properties of peptide molecules in solution. In order to study the effects of added ionic salts on protein conformation and dynamics, we have used the molecular dynamics (MD) simulations to investigate the behavior of Staphylococcus aureus Hfq protein under two different ionic concentrations: 0.1 M NaCl and 1.0 M NaCl in presence and absence of RNA (a hepta-oligoribonucleotide AU5G). Hfq, a global regulator of gene expression is highly conserved and abundant RNA-binding protein. It is already reported that in vivo the increase of ionic strength results in a drastic reduction of Hfq affinity for $Q{\beta}$ RNA and reduces the tendency of aggregation of Escherichia coli host factor hexamers. Our results revealed the crucial role of 0.1 M NaCl Hfq system on the bases with strong hydrogen bonding interactions and by stabilizing the aromatic stacking of Tyr42 residue of the adjacent subunits/monomers with the adenine and uridine nucleobases. An increase in RNA pore diameter and weakened compactness of the Hfq-RNA complex was clearly observed in 1.0 M NaCl Hfq system with bound RNA. Aggregation of monomers in Hfq and the interaction of Hfq with RNA are greatly affected due to the presence of high ionic strength. Higher the ionic concentration, weaker is the aggregation and interaction. Our results were compatible with the experimental data and this is the first theoretical report for the experimental study done in 1980 by Uhlenbeck group for the present system.