• Title/Summary/Keyword: sampling designs

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Evaluating the efficiency of treatment comparison in crossover design by allocating subjects based on ranked auxiliary variable

  • Huang, Yisong;Samawi, Hani M.;Vogel, Robert;Yin, Jingjing;Gato, Worlanyo Eric;Linder, Daniel F.
    • Communications for Statistical Applications and Methods
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    • v.23 no.6
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    • pp.543-553
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    • 2016
  • The validity of statistical inference depends on proper randomization methods. However, even with proper randomization, we can have imbalanced with respect to important characteristics. In this paper, we introduce a method based on ranked auxiliary variables for treatment allocation in crossover designs using Latin squares models. We evaluate the improvement of the efficiency in treatment comparisons using the proposed method. Our simulation study reveals that our proposed method provides a more powerful test compared to simple randomization with the same sample size. The proposed method is illustrated by conducting an experiment to compare two different concentrations of titanium dioxide nanofiber (TDNF) on rats for the purpose of comparing weight gain.

The Design of the Shared Memory in the Dual Core System (Dual Core 시스템에서 Shared Memory 기능 설계)

  • Jang, Seung-Ju;Lee, Gwang-Yong;Kim, Jae-Myeong
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.12 no.8
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    • pp.1448-1455
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    • 2008
  • This paper designs Shared Memory on the Dual Core system so that it operates a general System V IPC on the Linux O.S. Shared Memory is the technique that many processes can access to identical memory area. We treat Shared Memory in this paper among big two branches of Shared Memory which are SVR in a kernel step format. We design a share memory facility of Linux operating system on the Dual Core System. In this paper the suggesting design plan of share memory facility in Dual Core system is enhancing the performance in existing unity processor system as a dual core practical use. We attempt a performance enhance in each CPU for each process which uses a share memory.

Investigating Factors of Transitioned-Online Courses on Satisfaction and Learning Effectiveness in Higher Education during the Era of the COVID-19

  • BAO, Nguyen Van;CHO, Yooncheong
    • East Asian Journal of Business Economics (EAJBE)
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    • v.10 no.3
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    • pp.1-15
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    • 2022
  • Purpose - This study explored factors of online education that affect student dissatisfaction and learning effectiveness in higher education during the COVID-19 pandemic. Research design, data, and methodology - This study combined qualitative and quantitative designs. The qualitative part of this study involved in-depth interviews using a criteria-based purposive sampling technique. The quantitative part of this study consisted of an online survey. Results - The qualitative results revealed that students faced significant problems related to online learning, including a lack of learning environment, interaction, and support from the school. The quantitative results indicated that the effects of transitioned-online courses on student dissatisfaction were higher with student support, the interaction between students and instructors, online learning environment, and course organization and evaluation based on the order, while the effects on learning effectiveness were higher with the online learning environment, interaction between students and instructors, course organization and evaluation, and student support based on the order. Conclusion - The results implied that online learning in the era of the COVID 19 pandemic negatively affects student satisfaction and learning effectiveness. Policymakers and school leaders should improve students' satisfaction and learning effectiveness when confronted with the pandemic. Better policies should be adopted to improve better way of teaching in the era of COVID19.

Brand Personality and Consumer Behavior for Laptop Purchases in Nepal

  • Bharat RAI;Rewan Kumar DAHAL;Binod GHIMIRE
    • Journal of Distribution Science
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    • v.21 no.4
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    • pp.35-45
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    • 2023
  • Purpose: The study's objective was to examine the impact of brand personality dimensions on consumer behavior for laptop purchases in Nepal. Research Materials and Methods: The study included descriptive and explanatory research designs. A structured questionnaire with a purposive sampling method was employed to gather the necessary information for the study. The survey data were analyzed using a quantitative approach. The study used descriptive statistics to characterize the response conditions. Correlation analysis was used to investigate the relationship between brand personality dimensions and consumer behavior. Regression path analysis was employed to identify the effect of brand personality dimensions and consumer behavior. Results: The result of regression path analysis showed that the three dimensions - competency, ruggedness, and sophistication, have a significant effect on consumer behavior, and the two dimensions- sincerity and excitement do not have a substantial impact on consumer behavior in laptop buying in Nepal. Conclusions and Implications: Such findings can serve as pioneering empirical evidence and provide a framework for marketers and future studies in various scenarios. The study's findings can help marketing managers in handling information management. Manufacturers, wholesalers, and retailers can also use the results in formulating marketing strategies, and marketers need to be aware of such considerations for influencing consumer behavior.

Engineering characterization of intermediate geomaterials - A review

  • T. Ashok Kumar;Ramanandan Saseendran;V. Sundaravel
    • Geomechanics and Engineering
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    • v.33 no.5
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    • pp.453-462
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    • 2023
  • Intermediate Geomaterials (IGMs) are natural formation materials that exhibit the engineering behavior (strength and compressibility) between soils and rocks. The engineering behavior of such material is highly unpredictable as the IGMs are stiffer than soils and weaker/softer than rocks. Further, the characterization of such material needs exposure to both soil and rock mechanics. In most conventional designs of geotechnical structures, the engineering properties of the IGMs are either aligned with soils or rocks, and this assumption may end up either in an over-conservative design or under-conservative design. Hence, many researchers have attempted to evaluate its actual engineering properties through laboratory tests. However, the test results are partially reliable due to the poor core recovery of IGMs and the possible sample disturbance. Subsequently, in-situ tests have been used in recent years to evaluate the engineering properties of IGMs. However, the respective in-situ test finds its limitations while exploring IGMs with different geological formations at deeper depths with the constraints of sampling. Standard Penetration Test (SPT) is the strength-based index test that is often used to explore IGMs. Moreover, it was also observed that the coefficient of variation of the design parameters (which represents the uncertainties in the design parameters) of IGMs is relatively high, and also the studies on the probabilistic characterization of IGMs are limited compared with soils and rocks. With this perspective, the present article reviews the laboratory and in-situ tests used to characterize the IGMs and explores the shear strength variation based on their geological origin.

Development of Unmatched System Model for Iterative Image Reconstruction for Pinhole Collimator of Imaging Systems in Nuclear Medicine (핀홀콜리메이터를 사용한 핵의학영상기기의 순환적 영상 재구성을 위한 비동일 시스템 모델 개발)

  • Bae, Jae-Keon;Bae, Seung-Bin;Lee, Ki-Sung;Kim, Yong-Kwon;Joung, Jin-Hun
    • Journal of radiological science and technology
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    • v.35 no.4
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    • pp.353-360
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    • 2012
  • Diverse designs of collimator have been applied to Single Photon Emission Computed Tomography (SPECT) according to the purpose of acquisition; thus, it is necessary to reflect geometric characteristic of each collimator for successive image reconstruction. This study carry out reconstruction algorithm for imaging system in nuclear medicine with pinhole collimator. Especially, we study to solve sampling problem which caused in the system model of pinhole collimator. System model for a maximum likelihood expectation maximization (MLEM) was developed based on the geometry of the collimator. The projector and back-projector were separately implemented based on the ray-driven and voxel-driven methods, respectively, to overcome sparse sampling problem. We perform phantom study for pinhole collimator by using geant4 application for tomographic emission(GATE) simulation tool. The reconstructed images show promising results. Designed iterative reconstruction algorithm with unmatched system model effective to remove sampling problem artefact. Proposed algorithm can be used not only for pinhole collimator but also for various collimator system of imaging system in nuclear medicine.

Design of a Low-Power 8-bit 1-MS/s CMOS Asynchronous SAR ADC for Sensor Node Applications (센서 노드 응용을 위한 저전력 8비트 1MS/s CMOS 비동기 축차근사형 ADC 설계)

  • Jihun Son;Minseok Kim;Jimin Cheon
    • The Journal of Korea Institute of Information, Electronics, and Communication Technology
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    • v.16 no.6
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    • pp.454-464
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    • 2023
  • This paper proposes a low-power 8-bit asynchronous SAR ADC with a sampling rate of 1 MS/s for sensor node applications. The ADC uses bootstrapped switches to improve linearity and applies a VCM-based CDAC switching technique to reduce the power consumption and area of the DAC. Conventional synchronous SAR ADCs that operate in synchronization with an external clock suffer from high power consumption due to the use of a clock faster than the sampling rate, which can be overcome by using an asynchronous SAR ADC structure that handles internal comparisons in an asynchronous manner. In addition, the SAR logic is designed using dynamic logic circuits to reduce the large digital power consumption that occurs in low resolution ADC designs. The proposed ADC was simulated in a 180-nm CMOS process, and at a 1.8 V supply voltage and a sampling rate of 1 MS/s, it consumed 46.06 𝜇W of power, achieved an SNDR of 49.76 dB and an ENOB of 7.9738 bits, and obtained a FoM of 183.2 fJ/conv-step. The simulated DNL and INL are +0.186/-0.157 LSB and +0.111/-0.169 LSB.

Preferences about Senior Congregate Housing by Attitudes on Work and Leisure in Later Life (노후의 일 . 여가 태도에 따른 노인공동생활주택 선호 경향)

  • 홍형옥;유병선
    • Journal of Families and Better Life
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    • v.21 no.5
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    • pp.13-24
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    • 2003
  • Regarding leisure and work as very important in residential life of old ages, this study analyzed their preference by leisure and work for senior congregate housing, which can provide proper work and leisure activities for older people who are able to manage their social activities with healthy condition. It conducted a survey of middle aged of the 50's who would face problems of senior housing in 2010, with stratified sampling by region, sex and housing structure type. Totally 556 Questionnaires were used for the final analysis. The research results showed that, first, the group which was positive toward their works mostly had spouse of the age of early 50' s and work for professional, technological, managerial positions with good health. Second, the more positive group towards their work showed high willingness to move in senior congregate housing, than a negative group towards their work, and put a weight on the openness of shared space and facilities as well as various alarming equipments, common space, common programs and the ability of managers. Third, according to the attitudes toward leisure activities, there were differences in each group by housing structure type, education of their own or their spouses, monthly income, property, economic ability, health condition, living together with spouse, housing tenureship, and usable area of houses. The fourth was that those who enjoy active leisure activities presented high willingness to move in senior congregate housing than those of negative attitude and also there was a difference in managerial ways. Throughout the results of the study, it appeared that a group of positive attitude toward work and leisure, than that of negative attitude, recognized the importance of senior congregate housing which social and leisure programs could support. It implied necessary to develop housing for the older people who have enough ability to manage their leisure activity as well as their work. The study is likely to have a contribution to suggest practical data for helping the development of housing for self-reliant seniors by analyzing their preference on senior congregate housing by their attitudes toward work. The research for the factors of various designs and managements by leisure and work may become the following research theme of the study.

Development of energy-harvesting based safety apparel for night workers (야간 작업자를 위한 에너지 하베스팅 기반 안전의복 개발)

  • Yoon, Jung-A;Oh, Yujin;Oh, Hwawon;Lee, Younhee
    • The Research Journal of the Costume Culture
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    • v.26 no.4
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    • pp.503-518
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    • 2018
  • The purpose of this study is to illustrate the design of safety suits based on energy-harvesting technology, particularly targeting street cleaners who must work at night with high mobility. The design focuses on applying lightweight energy-harvesting tools and illuminant into the wear. The design development reflects feedback from testers collected via survey constituting a key methodology. The development process has two main stages. Each stage uses a process of design prototyping, internal examination, test sampling, test wearing, and wearers' feedback via survey that consists of questions on visibility, wearing convenience, and washability. The first stage results show the design of safety suits with energy-harvested LED illuminant inserted and the survey results collected from street cleaners dressed in 4 sample and 80 actual suits in total. Improved based on the first-stage survey results, the second stage designs the suits with detachable energy-harvested EL tape. From these 5 sample and 30 actual second-stage suits, the additional survey indicates that this second-stage design facilitates more visibility and convenience in washing and wearing than the first-stage design. Accordingly, one can expect that this new design can apply not only to safety suits for night workers but also to handicapped or outdoor sportswear applications in the future.

High-Efficiency Design of a Ventilation Axial-Flow Fan by Using Weighted Average Surrogate Models (가중평균대리모델을 이용한 환기용 축류송풍기의 고효율 최적설계)

  • Kim, Jae-Woo;Kim, Jin-Hyuk;Lee, Chan;Kim, Kwang-Yong
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.35 no.8
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    • pp.763-771
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    • 2011
  • An optimization procedure for the design of a ventilation axial-flow fan is presented in this paper. Flow analyses of the preliminary fan are performed by solving three-dimensional Reynolds-averaged Navier-Stokes equations via a finite-volume solver with the shear-stress transport turbulence model as a turbulence closure. Three variables, the hub-to-tip ratio and the stagger angles at the mid and tip spans, are selected for the optimization. The Latin-hypercube sampling method as a design-of-experiments technique is used to generate twenty-five design points within the design space. and the weighted average surrogate models, WTA1, WTA2, and WTA3, are applied for find optimal designs. The results show that the efficiency is considerably enhanced.