• Steel and Composite Structures
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• 제33권6호
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• pp.891-906
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• 2019

This study considers the instability behavior of sandwich plates considering magnetorheological (MR) fluid core and piezoelectric reinforced facesheets. As facesheets at the top and bottom of structure have piezoelectric properties they are subjected to 3D electric field therefore they can be used as actuator and sensor, respectively and in order to control the vibration responses and loss factor of the structure a proportional-derivative (PD) controller is applied. Furthermore, Halpin-Tsai model is used to determine the material properties of facesheets which are reinforced by graphene platelets (GPLs). Moreover, because the core has magnetic property, it is exposed to magnetic field. In addition, Kelvin-Voigt theory is applied to calculate the structural damping of the piezoelectric layers. In order to consider environmental forces applied to structure, the visco-Pasternak model is assumed. In order to consider the mechanical behavior of structure, sinusoidal shear deformation theory (SSDT) is assumed and Hamilton's principle according to piezoelasticity theory is employed to calculate motion equations and these equations are solved based on differential cubature method (DCM) to obtain the vibration and modal loss factor of the structure subsequently. The effect of different factors such as GPLs distribution, dimensions of structure, electro-magnetic field, damping of structure, viscoelastic environment and boundary conditions of the structure on the vibration and loss factor of the system are considered. In order to indicate the accuracy of the obtained results, the results are validated with other published work. It is concluded from results that exposing magnetic field to the MR fluid core has positive effect on the behavior of the system.

• 보건행정학회지
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• 제20권2호
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• pp.40-52
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• 2010

Health insurance fees are set by relative value scales and conversion factors. Since 2008 the conversion factor has been classified into 7 according to the provider type, and a separate contract has been made respectively. As such classification of the conversion factor reflects only the different characteristics of providers, however, further classification to reflect the different cost structures of providers is proposed. Cost varies according to the type of not only providers but also services each provider supply. In fact different cost structures of providers are the result of their different services. This study analyzed the cost structure of medical services to propose a new approach to the classification of the conversion factor. This study analyzed the cost structure of medical services using cost data constructed in the revision study of relative value scales. The cost data consist of doctor's fee, support staff's fee, cost of medical equipments, cost of medical supplies and indirect cost. The proportion of each cost component to the total cost was analyzed in terms of service department and service type. 72 service groups are defined in terms of the combination of service department and service type. Through cluster analysis, 72 service groups were reduced into 7 clusters each of which has a similar cost structure. Conversion factor is contracted annually to reflect the change in the cost of providing medical services. So the classification of conversion factor has to be based on the cost structures of medical services, not the characteristics of providers. Service clusters derived in this study can be used as a new classification for health insurance fee contract.

• 한국산학기술학회논문지
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• 제19권5호
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• pp.661-671
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• 2018

강판 콘크리트구조에 대한 국내 연구는 대체적으로 강도가 큰 원전 구조물에 초점을 맞추고 있다. 현재 안전성과 시공성 측면에서 유리한 SC구조는 특수구조물에만 한정되어 적용되어 왔으며, 최근 구조적으로 장점이 명확한 SC구조에 대해 일반건축물에 적용하기 위한 연구가 진행되고 있다. 본 연구에서는 SC 구조를 일반 건축물에 적용하기 위한 기초 연구로서 특히 SC 구조에서 중요한 요소인 콘크리트의 시멘트를 고로슬래그로 대체하여 친환경성에 부합한 구조체를 계획하기 위해 무시멘트 콘크리트를 적용한 SC 구조의 기본 설계 정보를 제시하고자 한다. 이 논문에서는 압축 특성, 중심 압축 하중을 받는 유효좌굴길이계수에 대해 연구하였다. 유효좌굴길이계수를 산정하기 위해서 판 이론을 적용하지 않고 오일러 기둥 이론으로 계산하였다. 유효좌굴길이계수를 계산할 때 필요한 변형률을 측정하여 강판의 항복강도, 강판의 좌굴 및 콘크리트가 파단되는 시점에서의 유효좌굴길이계수를 계산하였다. 또한, 세장비(B/t)를 변수로 최대 압축강도가 국외 및 국내 기준식에 부합하는 지를 검토하였으며 기둥 이론을 적용하여 실험체의 좌굴을 분석하고 측정된 강판의 변형률을 선택하는 방법에 따라 유효좌굴길이계수를 분석하여 기준식에서 제시하는 값과 비교하였다.

• 대한가정학회지
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• 제20권4호
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• pp.83-89
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• 1982

The purpose of this study was to analyze the 45 measuring items for the clothing construction in order to observe the factorial structure of items and to extract the common factor and the special unique factor from data. The sample for the study was drawn randomly out of senior high schoolgirls in Seoul urban area. The size of sample was 301 girls between age 16 and 18. The method of analysis was applied by the principal component analysis with orthogonal rotation after extraction of 9 major factors. All of the above data was analyzed by the computer installed at Seoul National University. From these analyses, the major findings can be summerized as follows: 1. The results of factor analysis generally indicated that the first factor was clustered with 15 items, length measures and height measures. The eigenvalue of the first factor was 16.5 and the cumulative percentage of variables 36.6%. 2. The second factor was clustered with width measures, girth measures and weight of 19 items. The eigenvalue of the second factor was 6.5 and the cumulative percentage of variables 51.0%.

• 한국생산제조학회지
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• 제8권2호
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• pp.73-79
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• 1999

Most of mechanical structures are combined of substructures such as beams and/or plates. There are few systems with unibody structures but are many systems with united body structures. Generally the dynamic a nalysis of whole structures is performed under alternation load. In the structure design, the analysis of each bolted joint is more important than others for zero severity. This paper presents the analysis method of contact stress distribution factor in the bolted joint with variable fastening torque on joints in the structure. At first, a static vibration test was performed to find out a nominal stress of bolt jointed plates from the relationship between natural frequency and nominal stress. Then a contact stress was computed at contact point between bolt and plate in the structure. It is believed that the proposed method has promisiong implications for safer design with index of contact stress distribution factor and has merits for cost-down and saving time at the beginning of vehicle development.

• 한국전기전자재료학회논문지
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• 제26권6호
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• pp.421-424
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• 2013

The Hall factor in a quantum well structure with X or L-type indirect conduction valleys is calculated for various strain conditions. The two-dimensional constant energy surfaces of occupied valleys are proven to be identical. As a result, the Hall factor depends on the relative direction of occupied valleys to the growth direction, regardless of the number of occupied valleys. This work is widely applicable to the two-dimensional structure with indirect conduction minima for any growth direction and under different strain conditions.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 하계학술대회 논문집
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• pp.806-808
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• 2001

In this thesis, specimens was manufactured in general method annexing PMB-PZT system ceramic, and the following conclusion has been deduced. In XRD, the crystal structure of ceramic has the tetragonal structure which is close to rombohedral structure, and consequently the specimen characterized by MPB was manufactured. According to dopping with xPMB, electromechanical factor(kp) little is changed. kp was maximum value 23.37[%] at xPMB 0.03[mol%]. mechanical quality factor(Qm) was maximum value 237.04 at xPMB 0.03[mo1%].

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 하계학술대회 논문집 Vol.3 No.2
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• pp.578-580
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• 2002

In this thesis, specimens was manufactured in general method annexing PMB-PZT system ceramic, and the following conclusion has been deduced. In XRD, the crystal structure of ceramic has the tetragonal structure which is close to rombohedral structure, and consequently the specimen characterized by MPB was manufactured. According to dopping with xPMB, electromechanical factor(kp) little is changed. kp was maximum value 23.37[%] at xPMB 0.03[mol%]. mechanical quality factor(Qm) was maximum value 237,04 at xPMB 0.03[mol%].

• 전자공학회논문지B
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• 제33B권5호
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• pp.17-24
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• 1996

In this paper, we present a robust performance improvement method for the NLCF(normalized left coprime factor) uncertain structure using loop shaping and the structure singular value. For this, we select weighting functions for a loop shaping considering condition numer, and transform the NLCF uncertain structure into the 4-block structure. However, we can't get a good performance on account of the restriction of weighting functions. To cope with this, we motivate the use of structured singular vlaue in the robust performance improvement procedure. After all, the robust performance improvement can be obtained by a factor W$_{a}$ and a scaling factor of D-K iteration.

• 무역상무연구
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• 제35권
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• pp.147-178
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• 2007

This study clarified a study of relationship of strategic alliance structure factor, partner selection criteria and performance awareness on the container liners alliance. In order to obtain such objective of study existing literature variables suitable to the container liner were perused and extracted. Research models for research development and three study hypothesis were set out and scope of investigation and samples were chosen. The research hypothesis are followings. H1: The factors of strategic alliance motivation influence the performance awareness. H2: The strategic alliance structure factors influence the performance awareness. H3: The factors of partner selection criteria influence the performance awareness. In the result of the empirical study, the hypothesis 1, hypothesis 2 were supported completely and hypothesis 3 was partially supported.