Now showing items 1-20 of 166

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    A block diagonal covariance matrix test and discriminant analysis of high-dimensional data 

    Poompong Kaewumpai; Samruam Chongcharoen (National Institute of Development, 2017)

    In this dissertation, a new test statistic for testing for a block diagonal covariance matrix structure with a multivariate normal population where the number of variables p exceeds the number of observations n is proposed. Whereas classical approaches such as the likelihood ratio test cannot be applied when p n  , the proposed test statistic is based on the ratio of the estimators of 2 tr and 2 trD , where  is the population covariance matrix and D is the population covariance matrix under the null hypothesis. Furthermore, ...
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    A dynamic asymmetric key agreement for broadcast encryption based on braid groups 

    Norranut Saguansakdiyotin; Pipat Hiranvanichakorn (National Institute of Development Administration, 2012)

    Broadcast encryption is the scheme that a sender encrypts messages for a designated group of receivers, and sends the ciphertexts by broadcasting over the networks. Many research papers have done it using elliptic curve cryptosystem. This research proposes a dynamic asymmetric key agreement protocols for the broadcast encryption which is based on braid groups cryptosystem, an alternative method in the public key cryptography in which it can reduce the computational cost. The proposed scheme is also used the concept of an identity-based ...
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    A filter-based feature selection using two criterion functions and evolutionary fuzzification 

    Jitwadee Chaiyakarn; Ohm Sornil (National Institute of Development Administration, 2013)

    In information age, data has become increasingly large, in both dimension (the number of features) and volume. Data mining processes, such as data classification and data clustering, performed on high dimensional data can be time-consuming and can produce poor results due to the problem so called curse of dimensionality. Feature selection is one of the fundamental techniques that selects only the most significant features and eliminates irrelevant and redundant features from the entire set of features. Filter-based feature selection is the ...
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    A framework for implementation of Thai to English machine translation systems 

    Tawee Chimsuk; Surapong Auwatanamongkol (National Institute of Development Administration, 2010)

    Machine translation (MT) is a sub-field of computational linguistics that investigates the use of computer software to translate text or speech from one language to another. It can help people to communicate with others with different natural languages. Machine Translation (MT) between Thai and English languages bas been an ongoing and challenging research topic. Most research has been done on English to Thai machine translation. but not the other way around. Developing a machine translation system which can correctly translate any sentence ...
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    A lossless image compression algorithm using predictive coding based on quantized colors 

    Fuangfar Pensiri; Surapong Auwatanamongkol, advisor (National Institute of Development Administration, 2011)

    Predictive coding has proven to be effective for lossless image compression. The predictive coding estimates true color of a pixel based on the true colors of its neighboring pixels. To enhance the accuracy of the estimation, we propose a new and simple predictive coding algorithm that uses the quantized colors of neighboring pixels to estimate the true color of a pixel. The estimation is based on the majority of quantized colors of the three neighboring pixels. Experiments, over a set of true color 24-bit images whose colors of pixels are quantized ...
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    A multilevel analysis of determinants of infant mortality in rural Northeastern Thailand 

    Nawarat Suwannapong; Suwanlee Piampiti, advisor (National Institute of Development Administration, 1987)

    The study utilized field survey data conducted from January 1986 to March 1986. Married women aged 15 to 49 years with experience of at least one live birth were randomly interviewed in depth. Only live births during the period January 1, 1980 to December 31, 1984 were analysed. For a better understanding of the infant mortality situation in Thailand, the author begins with the estimate of regional probability of dying between live birth and selected age by applying the indirect technique developed by Brass, Trussell and Feeney. The data for ...
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    A non-uniform bound on poisson approximation for dependent Bernoulli trials 

    Kanint Teerapabolarn; Samruam Chongcharoen, advisor (National Institute of Development Administration, 2005)
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    A permutation test for partial regression coefficients on first-order autocorrelation 

    Pradthana Minsan; Pachitjanut Siripanich, advisor (National Institute of Development Administration, 2010)

    This dissertation proposes a permutation test and a permutation procedure for testing on partial regression coefficients from a multiple linear regression with first-order autocorrelation where the distribution of the error terms is not necessarily normal. The proposed permutation procedure can be directly conducted in the test without having to fit back to the model, which is not the same procedure as in previous permutation tests, and a proposed permutation test is considered based on a random permutation test. In addition, the asymptotic ...
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    A study of changes in urbanization and occupational mobility of the Thai labour force 

    Chupensri Wongbuddha; Suchart Prasith-rathsint, advisor (National Institute of Development Administration, 1988)

    This study examines changes in the degree of urbanization in various types of a community and an individual's mobility in the three major occupational groups, agriculture, industry and service. Information was obtained from two levels, 1) a community level: a total of 503 communities was sampled from the 1970 and 1980 data tapes of Population and Housing Censuses, and 2) a personal level: a total of 720 households was sampled including 1,294 individuals of 35 years and over, selected for the survey and interviewed concerning their individual ...
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    A study of controlled sampling with varying probabilities without replacement 

    Wimon Sonchaem; Prachoom Suwattee, advisor (National Institute of Development Administration, 2001)
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    A study on employment and fertility of female migrant workers in the manufacturing industry of Bangkok and periphery areas 

    Kusol Soonthorndhada; Suwanlee Piampiti, chairperson (National Institute of Development Administration, 1991)

    The main objectives of this study were two fold. First, to study the general characteristics background in terms of socio-economic, demographic, employment and migration background of female workers in the manufacturing industry. Secondly, to assess the determinants of female workers' fertility and to examine the effect of fertility on employment. The data used in this study were selected ever married female workers from the survey of "Family Planning and Welfare Services for Female Workers in the Manufacturing Industry" conducted by Mahidol ...
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    A test for more than two poisson population means 

    Dechavudh Nityasuddhi; Prachoom Suwattee, chairperson (National Institute of Development Administration, 2003)
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    A test for repeated measurements designs with high dimensional data 

    Boonyarit Choopradit; Samruam Chongcharoen, advisor (National Institute of Development Administration, 2011)

    Repeated measurements across time on the same subject are frequently observed in several scientific fields. A new challenge to statisticians today is dealing with conditions where the dimension of repeated measurements per subject is larger than the number of subjects, called high dimensional data. High dimensional repeated measurements data are increasingly encountered in various areas of modern science because classical multivariate statistics are not well defined. In this dissertation, test statistics for analyzing high dimensional one- and ...
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    A test statistic for selection of multivariate linear regression models 

    Srisuda Boonyim; Jirawan Jitthavech (National Institute of Development Administration, 2015)

    In this study, a test statistic used to select a multivariate linear regression model based on Mallows’s Cp with the same rationale as the SCp criterion from the system of equations Vichit Lorchirachoonkul and Jirawan Jitthavech (2012: 2386- 2394) proposed. The D statistic, which is the difference between the modified Cp statistics in the reduced model and in the full model, approximates to a standard normal distribution.
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    A two-step algorithm to determine a sample size using random sampling for discovering association rules 

    Patcharee Wongkasem; Vichit Lorchirachoonkul, chairperson (National Institute of Development Administration, 2004)
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    Abstractive Thai opinion summarization 

    Orawan Chaowalit; Ohm Sornil (National Institute of Development Administration, 2013)

    With the advancement of the Internet technology, customers can easily share opinions about services and products in forms of reviews. There can be large amount of reviews for popular products. Manually summarizing those reviews for important issues is a daunting task. Automatic opinion summarization is a solution to the problem. The task is more complicated for reviews written in Thai. Thai words are written continuously without space, and there is no symbol to identify the end of a sentence. Many reviews are written informally, thus accurate ...
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    Accessibility to social security scheme of informal labors in Bangkok 

    Nirund Thiptananont; Pachitjanut Siripanich, advisor (National Institute of Development Administration, 2010)

    The purpose of this study was to examine the knowledge, satisfaction, acquisition of information, relative advantages, complexities, trustworthiness and effort of the government, among informal labour in Bangkok towards the social security scheme and also to study the relationship between these factors and participation in the social security scheme. The approach was survey research. The target population was labour having income but no social security at the age of 15-60 years. The sampling method was two-stage stratified sampling, ...
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    Alternative types of care and their impacts on the quality of the Thai elderly in the Bangkok Metropolitan Area 

    Sasithorn Tamarak; Somboonwan Satyarakwit, advisor (National Institute of Development Administration, 1996)

    In order to deal with an aging population increasing rapidly in numbers and proportion, a study into present care provisions, existing needs, an the quality of life of the Thai elderly is needed. Two research methods are employed: documentary research and survey research. Documentary research into the demographic profile of the Thai elderly is presented by obtaining data from the National Statistical Office which focuses on the transition of population structure and socioeconomic characteristics of the aging population. A decline in the proportion ...
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    An adaptive multi-level sequential floating feature selection 

    Knitchepon Chotchantarakun; Ohm Sornil (National Institute of Development Administration, 2020)

    Dealing with a large amount of available data becomes a major challenge in data mining and machine learning. Feature selection is a significant preprocessing step for selecting the most informative features by removing irrelevant and redundant features, especially for large datasets. These selected features play an important role in information searching and enhancing the performance of machine learning models such as classification and prediction. There have been several strategies proposed in the past few decades. In this dissertation, we ...
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    An alternative estimator for regression coefficients with outliers 

    Titirut Mekbunditkul; Pachitjanut Siripanich, advisor (National Institute of Development Administration, 2010)

    An important problem often found in a regression analysis is that a structural change in regression exists and/or the observed data contain outliers. These can lead to a violation of the Gauss-Markov assumptions and affect least squares (LS), rendering the regression inadequate. In this dissertation, an alternative regression model has been constructed from a combination of two principle ideas, namely the Tobit and piecewise regressions. This combined model, called the Tobit-piecewise (TP) regression model, can be suitably applied to cope with ...