• Structural Engineering and Mechanics
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• 제76권5호
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• pp.561-578
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• 2020

The present work addresses the surface integrity and chip morphology in finish hard turning of AISI D3 steel under nanofluid assisted minimum quantity lubrication (NFMQL) condition. The surface integrity aspects include microhardness, residual stress, white layer formation, machined surface morphology, and surface roughness. This experimental investigation aims to explore the feasibility of low-cost multilayer (TiCN/Al2O3/TiN) coated carbide tool in hard machining applications and to assess the propitious role of minimum quantity lubrication using graphene nanoparticles enriched eco-friendly radiator coolant based nano-cutting fluid for machinability improvement of hardened steel. Combined approach of central composite design (CCD) - analysis of variance (ANOVA), desirability function analysis, and response surface methodology (RSM) have been subsequently employed for experimental investigation, predictive modelling and optimization of surface roughness. With a motivational philosophy of "Go Green-Think Green-Act Green", the work also deals with economic analysis, and sustainability assessment under environmental-friendly NFMQL condition. Results showed that machining with nanofluid-MQL provided an effective cooling-lubrication strategy, safer and cleaner production, environmental friendliness and assisted to improve sustainability.

• Journal of Ginseng Research
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• 제36권4호
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• pp.449-460
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• 2012

Plants have versatile detoxification systems to encounter the phytotoxicity of the wide range of natural and synthetic compounds present in the environment. Glutathione S-transferase (GST) is an enzyme that detoxifies natural and exogenous toxic compounds by conjugation with glutathione (GSH). Recently, several roles of GST giving stress tolerance in plants have demonstrated, but little is known about the role of ginseng GSTs. Therefore, this work aimed to provide further information on the GST gene present in Panax ginseng genome as well as its expression and function. A GST cDNA (PgGST) was isolated from P. ginseng cDNA library, and it showed the amino acid sequence similarity with theta type of GSTs. PgGST in ginseng plant was induced by exposure to metals, plant hormone, heavy metals, and high light irradiance. To improve the resistance against environmental stresses, full-length cDNA of PgGST was introduced into Nicotiana tabacum. Overexpression of PgGST led to twofold increase in GST-specific activity compared to the non-transgenic plants, and the GST overexpressed plant showed resistance against herbicide phosphinothricin. The results suggested that the PgGST isolated from ginseng might have a role in the protection mechanism against toxic materials such as heavy metals and herbicides.

• Human Ecology Research
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• 제53권4호
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• pp.391-404
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• 2015

This study examined job satisfaction and relevant variables for multi-cultural family home-visiting educators. The selected study subjects were 192 home-visiting educators who work at Multi-Cultural Family Support Centers in the Seoul, Gyeonggi-do, and Chungcheongnam-do areas. Data analysis was conducted using SPSS ver. 18.0. The main results were as follows. First, the job satisfaction level in multi-cultural family visiting educators stood at 3.29 points, subjects' age, averagely monthly income, marital status, and activity career were shown to influence generally upon job satisfaction, self-efficacy, job stress, and cultural competency. Job satisfaction was high in groups with: a high age, small career, low averagely monthly income, and married. Second, self-efficacy and job stress were big in the job satisfaction of multi-cultural family visiting educators. The same outcome as the existing prior research was indicated. Cultural competency was not significant. Third, an examination of relative influence upon job satisfaction in home visiting educators indicated that the explanation power was 29.0%. Significant influential variables included academic background, marital status, self-regulation, and role ambiguity. Self-regulation was greater for those with lower academic backgrounds and unmarried. Job satisfaction was higher in the lower role ambiguity. Thus, the same outcome as the existing prior research was indicated. Cultural competency wasn't indicated to be significant. This has significance in having shown characteristics of job satisfaction in multi-cultural family visiting educators.

• Genomics & Informatics
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• 제20권4호
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• pp.45.1-45.7
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• 2022

Food security will be affected by climate change worldwide, particularly in the developing world, where the most important food products originate from plants. Plants are often exposed to environmental stresses that may affect their growth, development, yield, and food quality. Auxin is a hormone that plays a critical role in improving plants' tolerance of environmental conditions. Auxin controls the expression of many stress-responsive genes in plants by interacting with specific cis-regulatory elements called auxin-responsive elements (AuxREs). In this work, we performed an in silico prediction of AuxREs in promoters of five auxin-responsive genes in Zea mays. We applied a data fusion approach based on the combined use of Dempster-Shafer evidence theory and fuzzy sets. Auxin has a direct impact on cell membrane proteins. The short-term auxin response may be represented by the regulation of transmembrane gene expression. The detection of an AuxRE in the promoter of prolyl oligopeptidase (POP) in Z. mays and the 3-fold overexpression of this gene under auxin treatment for 30 min indicated the role of POP in maize auxin response. POP is regulated by auxin to perform stress adaptation. In addition, the detection of two AuxRE TGTCTC motifs in the upstream sequence of the bx1 gene suggests that bx1 can be regulated by auxin. Auxin may also be involved in the regulation of dehydration-responsive element-binding and some members of the protein kinase superfamily.

• 정보화정책
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• 제26권4호
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• pp.36-61
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• 2019

스마트기기는 업무의 시공간적 제약을 줄이고 신속한 처리를 가능하게 함에 따라 업무 효율성 및 생산성에 긍정적인 영향을 줄 수 있는 반면에, 직장과 개인생활 간 불균형 초래로 인한 부작용이 뒤따를 수 있다. 최근 스마트기기의 업무활용이 증가하면서 그 어느때보다도 관련 현상의 이해와 원인 발견, 그에 맞는 적절한 방안들을 모색하는 것이 필요한 상황이다. 본 연구는 스마트기기의 효용성을 대표하는 기술적 특성('IT기반 업무 유연성')이 '일-삶 갈등'과 같은 부정적인 결과로 어떻게 전환되는지를 보여주는 이론적 모델을 개발하고 이를 검증하였다. 직장인을 대상으로 수집된 데이터를 분석한 결과, 주요 요인들('IT기반 업무 유연성', '근무시간 외 업무 유연성', '업무 과부하', '일-삶 갈등') 간 다양한 영향 관계, 그리고 ''일-삶 분리' 조직 지원'의 중요성과 관련하여 연구자는 물론이고 현업 종사자와 정책 입안자들에게도 의미있는 시사점이 도출되었다.

• 한국사회복지학
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• 제37권
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• pp.241-269
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• 1999

본 연구는 사회적 지지가 실직자의 심리사회적 안녕감에 갖는 영향을 탐구함으로서 사회적 지지이론에 대한 경험적 분석과 실직자를 위한 사회복지서비스 전략개발을 목적으로 수행되었다. 충청북도, 충주시 및 인근지역에 거주하는 369명의 실직자를 대상으로 설문조사를 실시, 사회적 지지가 실직자의 심리사회적 상태에 미치는 주효과(main effect)가설과 스트레스 완충효과(stress buffering effect)가설을 탐구하였다. 연구결과는 사회적 지지의 주효과가설과 스트레스 완충효과가설의 부분적인 검증을 시사하였다. 사회적 지지의 주효과에 대한 검증에서는 가족으로부터의 지지가 표본 실직자들에게 가장 유용한 사회적 지지의 출처였고 실직자의 심리사회적 안녕감에 가장 긍정적인 영향을 주는 요인으로 밝혀졌다. 또 사회적 지지의 스트레스완충효과가설이 검증이 된 경우에도 완충효과는 그다지 크지 않았던 것으로 분석되었다. 본 연구결과를 바탕으로 사회적 지지의 이론 검증을 위한 추후연구방향이 제시되었고 실직자를 위한 사회복지서비스 개발전략에 대한 시사점이 제기되었다.

• Structural Engineering and Mechanics
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• 제35권6호
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• pp.677-697
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• 2010

This paper focuses on geometrically non-linear static analysis of a simply supported beam made of hyperelastic material subjected to a non-follower transversal uniformly distributed load. As it is known, the line of action of follower forces is affected by the deformation of the elastic system on which they act and therefore such forces are non-conservative. The material of the beam is assumed as isotropic and hyperelastic. Two types of simply supported beams are considered which have the following boundary conditions: 1) There is a pin at left end and a roller at right end of the beam (pinned-rolled beam). 2) Both ends of the beam are supported by pins (pinned-pinned beam). In this study, finite element model of the beam is constructed by using total Lagrangian finite element model of two dimensional continuum for a twelve-node quadratic element. The considered highly non-linear problem is solved by using incremental displacement-based finite element method in conjunction with Newton-Raphson iteration method. In order to use the solution procedures of Newton-Raphson type, there is need to linearized equilibrium equations, which can be achieved through the linearization of the principle of virtual work in its continuum form. In the study, the effect of the large deflections and rotations on the displacements and the normal stress and the shear stress distributions through the thickness of the beam is investigated in detail. It is known that in the failure analysis, the most important quantities are the principal normal stresses and the maximum shear stress. Therefore these stresses are investigated in detail. The convergence studies are performed for various numbers of finite elements. The effects of the geometric non-linearity and pinned-pinned and pinned-rolled support conditions on the displacements and on the stresses are investigated. By using a twelve-node quadratic element, the free boundary conditions are satisfied and very good stress diagrams are obtained. Also, some of the results of the total Lagrangian finite element model of two dimensional continuum for a twelve-node quadratic element are compared with the results of SAP2000 packet program. Numerical results show that geometrical nonlinearity plays very important role in the static responses of the beam.

• The Korean Journal of Physiology and Pharmacology
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• 제24권5호
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• pp.373-384
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• 2020

Paeonol, quercetin, β-sitosterol, and gallic acid extracted from Moutan Cortex had been reported to possess anti-oxidative, anti-inflammatory, and anti-tumor activities. This work aimed to illustrate the potential anti-oxidative mechanism of monomers in human liver hepatocellular carcinoma (HepG2) cells-induced by hydrogen peroxide (H₂O₂) and to evaluate whether the hepatoprotective effect of monomers was independence or synergy in mice stimulated by carbon tetrachloride (CCl₄). Monomers protected against oxidative stress in HepG2 cells in a dose-response manner by inhibiting the generation of reactive oxygen species, increasing total antioxidant capacity, catalase and superoxide dismutase (SOD) activities, and activating the antioxidative pathway of nuclear factor E2-related factor 2/Kelch-like ECH-associated protein 1 (Nrf2/Keap1) signaling pathway. We found that the in vitro antioxidant capacities of paeonol and quercetin were better than those of β-sitosterol and gallic acid. Furthermore, paeonol apparently diminished the levels of alanine transaminase and aspartate aminotransferase, augmented the contents of glutathione and SOD, promoted the expressions of Nrf2 and heme oxygenase-1 proteins in mice stimulated by CCl₄. In HepG2 cells, paeonol, quercetin, β-sitosterol, and gallic acid play a defensive role against H₂O₂-induced oxidative stress through activating Nrf2/Keap1 pathway, indicating that these monomers have anti-oxidative properties. Totally, paeonol and quercetin exerted anti-oxidative and hepatoprotective effects, which is independent rather than synergy.

• Safety and Health at Work
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• 제2권4호
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• pp.365-374
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• 2011

Objectives: This study was designed to investigate whether long-term, low-level exposure to monocyclic aromatic hydrocarbons (MAHs) induced insulin resistance. Methods: The subjects were 110 male workers who were occupationally exposed to styrene, toluene, and xylene. One hundred and ten age-matched male workers who had never been occupationally exposed to organic solvents were selected as a control group. Cytokines, which have played a key role in the pathogenesis of insulin resistance, and oxidative stress indices were measured. Assessment of exposure to MAHs was performed by measuring their ambient levels and their urinary metabolites in exposed workers, and the resulting parameters between the exposed group and non-exposed control groups were compared. Results: There was no significant difference in general characteristics and anthropometric parameters between the two groups; however, total cholesterol, fasting glucose, fasting insulin, and homeostasis model assessment of insulin resistance levels were significantly higher in the exposed group. Phenylglyoxylic acid levels showed significant association with tumor necrosis factor-${\alpha}$, total oxidative status, and oxidative stress index via multiple linear regression analysis. Further, there was a negative correlation between methylhippuric acid levels and total anti-oxidative capacity, and there was a significant relationship between MAHs exposure and fasting glucose levels, as found by multiple logistic regression analysis (odds ratio = 3.95, 95% confidence interval = 1.074-14.530). Conclusion: This study indicated that MAHs increase fasting glucose level and insulin resistance. Furthermore, these results suggested that absorbing the organic solvent itself and active metabolic intermediates can increase oxidative stress and cytokine levels, resulting in the changes in glucose metabolism and the induction of insulin resistance.

• 한국융합학회논문지
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• 제10권9호
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• pp.311-321
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• 2019

본 연구는 요양보호사의 소진에 미치는 영향요인을 파악하고, 이를 기반으로 요양보호사의 소진감소프로그램 개발을 위한 기초자료를 제공하기 위하여 시도된 융합연구이다. 연구대상자는 G시 소재한 요양보호시설에 6개월 이상 근무한 요양보호사 중 연구목적을 이해하고 자발적으로 연구에 참여를 동의한 대상자에게 2015년 9월 설문지를 배부하여 총 185부를 분석하였다. 자료분석은 t-test, one-way ANOVA, $Scheff{\acute{e}}$ test, Pearson's correlation coefficient 및 Stepwise multiple regression을 구하여 분석하였다. 요양보호사의 소진에 미치는 영향요인은 개인역할 및 일상업무요인 스트레스(${\beta}=.307$, p<.001), 상사관계 스트레스(${\beta}=.186$, p<.021), 자신감(${\beta}=.182$, p<.005) 및 소극적 대처방식(${\beta}=.140$, p<.035)으로 총 27.5%의 설명력을 보였다. 본 연구결과를 토대로 요양보호사의 소진을 감소시키기 위해서는 스트레스를 감소하고 자신감을 상승과 더불어 대처방식을 다양화 할 수 있는 소진감소 프로그램 개발이 필요할 것으로 사료된다.