• 대한수학회보
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• 제43권2호
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• pp.299-307
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• 2006

The following results ale extended from P-injective rings to AP-injective rings: (1) R is left self-injective regular if and only if R is a right (resp. left) AP-injective ring such that for every finitely generated left R-module M, $_R(M/Z(M))$ is projective, where Z(M) is the left singular submodule of $_{R}M$; (2) if R is a left nonsingular left AP-injective ring such that every maximal left ideal of R is either injective or a two-sided ideal of R, then R is either left self-injective regular or strongly regular. In addition, we answer a question of Roger Yue Chi Ming [13] in the positive. Let R be a ring whose every simple singular left R-module is Y J-injective. If R is a right MI-ring whose every essential right ideal is an essential left ideal, then R is a left and right self-injective regular, left and right V-ring of bounded index.

• 대한정형외과 초음파학회지
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• 제3권1호
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• pp.15-20
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• 2010

목적: 슬관절 초음파가 활액 양의 측정에서 신체 검사 및 단순 방사선 검사 소견과 비교하여 얼마나 유용한가를 알아 보고자 하였다. 대상 및 방법: 슬관절의 활액 증가가 의심되는 60예의 슬관절을 대상으로 하였다. 평균 나이는 61.3세, 여자 38명, 남자 22명 이였고, 비만하지 않은 사람이 24명, 비만한 사람이 36명 이였다. 신체 검사는 stroke test와 슬개골 부구 검사를 시행하였고, 방사선 소견은 측면 상에서 활액 양을 관찰하여 3단계로 분류하였으며, 초음파로 이를 확인하여 비교 분석하였다. 결과: stroke test는 39예에서 양성, 슬개골 부구 검사는 20예에서 양성을 보였고, 방사선 측면 검사는 1단계 47예, 2단계 7예, 3단계 3예로 관찰되었다. 초음파 검사는 평균 $7.67{\pm}2.90mm$의 활액 양이 관찰되었다. stroke test와 슬개골 부구 검사, 측면 방사선 검사 모두 초음파 검사와 양의 상관관계에 있었다(r=.405, .259, .714). 성별은 신체 검사에서는 상관관계의 큰 차이를 보이고 있지 않았고 측면 방사선 검사에서는 여성에서 강한 상관관계를 보였다(r=.789). 비만한 사람보다 비만하지 않은 사람이 세 검사 모두에서 더 강한 상관관계를 보였다. 신체 검사는 비만하지 않은 사람에서는 비교적 유용하였으나 비만한 사람에서는 부정확하였으며, 방사선 검사 상에서도 활액 정도 파악이 어려웠으나 초음파 상으로는 활액의 두께를 동적으로 측정하여 과학적 데이터를 얻을 수 있었다. 결론: 슬관절 활액 양의 측정에서는 초음파가 신체 검사나 방사선 소견에 비해 객관적 데이터를 얻을 수 있어 유용하였다.

• 국제물리치료학회지
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• 제9권2호
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• pp.1455-1460
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• 2018

This study aimed to determine the effect of depression between the health-related quality of life and pain in elderly persons with physical disabilities. A total of 111 patients who were treated at hospital B (Seoul, Daejeon, Daegu, Gwangju, and Busan) participated in the Survey. The SF-36 Health Assessment was used to determine the quality of life of subjects, the Korean version of the Geriatric Depression Scale-Short form to assess the level of depression, and Numeric Rating Scale to determine the level of pain. To determine the moderating effect of depression on the relationship between quality of life and pain, simple regression analysis, and the Sobel test were performed. There was a significant negative correlation between health-related quality of life and pain (r<-.3, p<.05), and a significant positive correlation between depression and pain (r=.251, p<.05). Thus, health-related quality of life had a simple regression relationship with depression and pain. Depression also showed a mediating effect between health-related quality of life and pain. The results of this study suggest that depression mediates between pain and quality of life.

• Steel and Composite Structures
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• 제25권3호
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• pp.257-270
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• 2017

In this article, an efficient and simple refined theory is proposed for buckling analysis of functionally graded plates by using a new displacement field which includes undetermined integral variables. This theory contains only four unknowns, with is even less than the first shear deformation theory (FSDT). Governing equations are obtained from the principle of virtual works. The closed-form solutions of rectangular plates are determined. Comparison studies are carried out to check the validity of obtained results. The influences of loading conditions and variations of power of functionally graded material, modulus ratio, aspect ratio, and thickness ratio on the critical buckling load of functionally graded plates are examined and discussed.

• Journal of Plant Biology
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• 제26권1호
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• pp.7-16
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• 1983

Internodal vessel elements are studied in 20 genera, 75 species and 33 cultivars of Hibiscus rosa-sinensis belong to the Malvaceae. The minimum and maximum length and diameter range from 79~466 and 14~88 ${\mu}{\textrm}{m}$, respectively. The vessel elements are either cylindrical, fusiform, conical, clavate, oval, column-, drum-, fish and cup-like or erratic. Perforation plates are exclusively simple in all the species investigated, except occasionally scalariform in varieties of Hibiscus rosa-sinensis. In most of the species studied vessel elements have predominantly two perforation plates or occasionally one and three. Adjacen side wall thickening is commonly simple and border pitted, mixed, scalariform, helical and reticulate. The vessel elements vary in their size, shape, number and inclination of perforation plates and adjacent wall thickening.

• Computers and Concrete
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• 제8권1호
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• pp.97-110
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• 2011

In this paper, FEM procedure is applied to the static and dynamic analyses of R/C structures. Simple R/C shell structure is solved by using FEM procedures and the experimental evaluations are performed to represent the applicability of FEM procedure to R/C structures. Also, R/C columns are analyzed numerically and experimentally. On the basis of these results, FEM procedures are applied to the R/C cooling tower structures assembled by huge R/C shell structure and a lot of discrete R/C columns. In this analysis, the parallel computing procedures are introduced into these analyses to reduce the computational effort. The dynamic performances of R/C cooling tower are also solved by the application of parallel computations as well. From the numerical analyses, the conventional FEM procedures combined with computational technologies enables us to design the huge R/C structures statically and dynamically.

• Korea-Australia Rheology Journal
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• 제14권1호
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• pp.25-32
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• 2002

We report the first steps of a collaborative project between the University of Queensland, Polyflow, Michelin, SK Chemicals, and RMIT University, on simulation, validation and application of a recently introduced constitutive model designed to describe branched polymers. Whereas much progress has been made on predicting the complex flow behaviour of many - in particular linear - polymers, it sometimes appears difficult to predict simultaneously shear thinning and extensional strain hardening behaviour using traditional constitutive models. Recently a new viscoelastic model based on molecular topology, was proposed by McLeish and carson (1998). We explore the predictive power of a differential multi-mode version of the porn-pom model for the flow behaviour of two commercial polymer melts: a (long-chain branched) low-density polyethylene (LDPE) and a (linear) high-density polyethylene (HDPE). The model responses are compared to elongational recovery experiments published by Langouche and Debbaut (19c99), and start-up of simple shear flow, stress relaxation after simple and reverse step strain experiments carried out in our laboratory.

• 한국시뮬레이션학회논문지
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• 제12권1호
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• pp.11-19
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• 2003

Dubins showed that any shortest path of a car-like robot consists of exactly three path segment which are either arcs of circles of radius r(denoted C), or straight line segments(denoted S). Possible six types classified into two families, i.e. CSC and CCC. CSC includes 2 types(LRL and RLR) and CSC includes 4 types(LSL, RSR, LSR, RSL). This paper proposes new formulae for CSC family to find the shortest smooth path between the initial and final configurations of a car-like robot. The formulae is used for finding connection points explicitly between C\longrightarrowS and S\longrightarrowC which are necessary for real applications. The formulae have simple forms mainly because they are transformed into origin of their original coordinates of initial and target configuration, and derived from a standard forms which are a representative configuration of LSL and LSR type respectively. The proposed formulae, which are derived from the standard forms, are simple and new method.

• Journal of Power Electronics
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• 제19권3호
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• pp.815-826
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• 2019

This paper discusses a simple control approach for a Unified Power Conditioner (UPC) system to achieve power quality compensation at the point of common coupling in distribution systems. The proposed Instantaneous Power Estimation Algorithm (IPEA) for shunt and series active power filters uses a simple mathematical concept that reduces the complexity in the design of the controller. The performance of a UPC is verified with a system subjected to voltage distortions, sags/swells and unbalanced loads using MATLAB/SIMULINK. The simulation study shows that a UPC with the proposed control algorithm can effectively compensate for voltage and current harmonics, unbalance and reactive power. The control algorithm is experimentally implemented using dSPACE DS1104 and its effectiveness has been verified.

• Journal of Nutrition and Health
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• 제31권3호
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• pp.354-362
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• 1998

The purposes of this study were to develop standardized indices of staffing needs in each school, foodservice system through work sampling methodology . Conventional school foodservices were classified into 5 groups depending on size of meals served. Commissary school foodservices were also classified into 5 groups by cluster analysis using number of meals served, number of satellite schools, and time for transportation of food. Work measurement through work sampling methodology was conducted in 15 conventional and 21 commissary foodservices during 3 consecutive days from September to October in 1995. Statistical data analysis was completed using the SAS programs for descriptive analysis, cluster analysis, and simple linear regression. The results were as follows : Average points of leveling factors of conventional and commissary foodservices were 1.066 and 1.061 , respectively. Mean labor hours per work force was 328 minutes and 366 minutes in conventional and commissary foodservice , respectively. Standardized work time was calculated using leveling factor, ILO allowance rate (175) , and observational work time. The model for standardized indices of staffing needs was developed based on simple linear regression in each school foodservice system. In conventional school foodservice systems(for 100-1,900 meals per day) standardized staffing needs=3.2497 +0.005267$\times$number of meals served (F=273.1, R-square 0.9750, p<0.001). In commissary school foodservice systems (for 200-1,600 meals per day ) Standardized staffing needs=3.393384 +0.0063$\times$number of meals served (F=30.78, R-square 0.6580, p<0.001).