• Communications for Statistical Applications and Methods
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• v.4 no.2
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• pp.541-548
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• 1997

In regression model with nested error structure interval estimations on regression coefficients in different stages are proposed. Ordinary least square estimators and generalized least square estimators of the regression coefficients in this model are derived for between and within group model. The confidence intervals are dervied by using independent idstributional properties between regression coefficient estimators and quadratic froms obtained from the model.

• Journal of Agricultural Extension & Community Development
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• v.22 no.3
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• pp.321-332
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• 2015

For the purpose of enhancing the use of social service in classrooms, this research focuses on the relationships between presence and learning flow, key words in the analysis of college classes using Facebook. The results of this study are as follow. First, social presence(${\ss}=.33$, p=.000), emotional presence(${\ss}=.29$, p= .000), cognitive presence(${\ss}=.20$, p= .010) were found to be significant according to cognitive flow experience the result of analysis of multiple regression. all regression coefficients were positive. Second, emotional presence(${\ss}=.42$, p=.000) and social presence(${\ss}=.27$, p=.000), cognitive, presence(${\ss}=.17$, p=.015) were found to be significant according to emotional flow experience the result of analysis of multiple regression. all regression coefficients were positive. Third, social presence(${\ss}=.37$, p=.000) of the three variables were found to be significant according to behavioral flow experience the result of analysis of multiple regression.

• Proceedings of the KSME Conference
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• 2001.11b
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• pp.274-279
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• 2001

An experimental investigation of heat transfer characteristics at the surface of two-dimensional protruding heated blocks using confined impinging multiple slot jets has been performed. The effects of jet-to-jet distances(S=16B, 24B), dimensionless nozzle-to-block distances(H/B=2, 6) and jet Reynolds numbers(Re=2000, 3900, 5800, 7800) on the local and average heat transfer coefficients have been examined with five isothermally heated blocks at streamwise block spacing(p/w=1). To clarify local heat transfer characteristics, naphthalene sublimation technique was used. From the results, it was found that the local and average heat transfer of heated blocks increases with decreasing jet-to-jet distance and increasing jet Reynolds number. Measurements of local heat transfer coefficients have given an indication of the nature of the interaction between jets and of the uniformity of heat transfer obtainable with various arrangements. In the case of S/B=16, H/B=6 and Re=7800, maximum average Nusselt number of overall blocks was obtained.

• Journal of Korea Multimedia Society
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• v.20 no.2
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• pp.244-253
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• 2017

Reversible DNA watermarking is capable of continuous DNA storage and forgery prevention, and has the advantage of being able to analyze biological mutation processes by external watermarking by iterative process of concealment and restoration. In this paper, we propose a reversible DNA watermarking method based on histogram multiple shifting of noncoding DNA sequence that can prevent false start codon, maintain original sequence length, maintain high watermark capacity without biologic mutation. The proposed method transforms the non-coding region DNA sequence to the n-th code coefficients and embeds the multiple bits of the n-th code coefficients by the non-recursive histogram multiple shifting method. The multi-bit embedding process prevents the false start codon generation through comparison search between adjacent concealed nucleotide sequences. From the experimental results, it was confirmed that the proposed method has higher watermark capacity of 0.004-0.382 bpn than the conventional method and has higher watermark capacity than the additional data. Also, it was confirmed that false start codon was not generated unlike the conventional method.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.1C
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• pp.68-78
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• 2008

The transmission of multimedia information over error-prone channels such as wireless networks has become an important area of research. In this paper, we propose two Error Concealment(EC) schemes for wireless transmission of JPEG2000 image. The Multiple Representation(MR) is employed as the preprocessing in our schemes, whereas the main error concealing operation is applied in wavelet domain at receiver side. The compressed code-stream of several subsampled versions of original image is transmitted over a single channel with random bit errors. In the decoder side, the correctly reconstructed wavelet coefficients are utilized to recover the corrupted coefficients in other sub-images. The recovery is carried out by proposed basic(MREC-BS) or enhanced(MREC-ES) methods, both of which can be simply implemented. Moreover, there is no iterative processing during error concealing, which results a big time saving. Also, the simulation results confirm the effectiveness and efficiency of our proposed schemes.

• Journal of The Korean Society of Agricultural Engineers
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• v.52 no.6
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• pp.1-7
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• 2010

This study was carried out to investigate the effect of hydro power factors (e.g., irrigation area, watershed area, active storage, gross head) on annual generation capacity and operation ratio for agricultural reservoirs in Chungbuk Province with active storage of over 1 million $m^3$. The annual generation capacity and operation ratio were estimated using HOMWRS (Hydrological Operation Model for Water Resources System) from last 10-year daily hydrological data. The correlation coefficients between annual generation capacity and the hydro power factors except gross head were high (over 0.87), but the correlation coefficients between operational rate and the factors were low (below 0.28). The optimum multiple regression equations of the annual generation capacity were expressed as the functions of watershed area, active storage, and gross head. Also, the simple regression equation of annual generation capacity was expressed as a function of watershed area. The average relative root-mean-square-error (RRMSE) between observed and estimated values by the optimum multiple regression equations was smaller than that by the simple regression equation, suggesting that the former has more accuracy than the latter.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.11 no.8
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• pp.3935-3949
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• 2017

In this paper, a novel multiple description image coding (MDC) scheme is proposed, which is based on the characteristics of the human visual model. Due to the inherent characteristics of human vision, the human eye can only perceive the change of the specific thresholds, that is, the just noticeable difference (JND) thresholds. Therefore, JND model is applied to improve MDC syetem. This paper calculates the DCT coefficients firstly, and then they are compared with the JND thresholds. The data that is less than the JND thresholds can be neglected, which will improve the coding efficiency. Compared with other existing methods, the experimental results of the proposed method are superior.

• Nutritional Sciences
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• v.6 no.3
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• pp.173-184
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• 2003

Objective : This study was carried out to develop a semi-quantitative food frequency Questionnaire (SQFFQ) for estimating average dietary intake to determine the risk factor for lifestyle-related diseases in a conjoint cohort study. Design : We developed an SQFFQ for genomic epidemiological studies based on the data in the'98 Korea Health and Nutrition Examination Survey. A subset of data on informative food items was collected using the 24-hr recall method with 2,714 adults aged 40 or older living in middle-sized cities or in rural areas in Korea. The cumulative percent contribution and cumulative multiple regression coefficients of 17 nutrients (energy, fat, carbohydrate, protein, fiber, iron, potassium, sodium, calcium, phosphorus, vitamin A, retinol, $\beta$-carotene, vitamin $B_1$, vitamin $B_2$, niacin and vitamin C) of each food were computed. Results : Two hundred and forty-nine foods, which were selected based on their 0.9 cumulative percent contribution, and 254 foods, which were selected based on their 0.9 cumulative multiple regression coefficients, respectively, were grouped into 97 food groups according to their nutrient contents. Several popular Korean foods, which were missing from the list due to the seasonality of the survey, were included. The portion sizes were derived from the same data set. The SQFFQ covered 84.8 percent of the intake of 17 nutrients in the one day diet record data of our 326 cohort study subjects. Conclusions . The final list included 103 food items. The foods list in the SQFFQ described herein accounted for 84.8 percent of the average intake of 17 nutrients. Therefore, the list could be used for the assessment of the baseline dietary intakes of the conjoint cohort studies.

• The KIPS Transactions:PartB
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• v.10B no.4
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• pp.419-428
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• 2003

Recently, digital watermarking has been proposed as a viable solution to the need of copyright protection and authentication of multimedia data. A robust wavelet-based watermark casting scheme and a watermark retrieval technique are suggested in this paper. We present a method which can add the watermark to the significant coefficients in the DWT domain, and does not require the original image in the detection process. In adaptive watermark casting method is developed to select perceptually significant coefficients for each subband using multiple threshold. In the proposed method, an adaptive multiple threshold scheme is used to reflect characteristics of each subband and complexity of image. The watermark is adaptively weighted in different subbands to achieve robustness as well as high perceptual quality. The watermark, Gaussian random sequence is added to the large coefficients but not in the lowest subband in the DWT domain. Experimental results show that the proposed algorithm produced visually very good watermarked image which has good invisibility to human eyes and very robust against various image processing and compression attacks.

• Progress in Superconductivity and Cryogenics
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• v.9 no.3
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• pp.37-40
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• 2007

Large critical current is one of the prerequisites for the design of superconducting electrical equipments with large power capacity. To enlarge the critical current. multiple parallel connection is inevitable. In multiple parallel superconducting coils. the difference in normal resistance of each shunt leads to unequal current distribution. which may yield burnout. Therefore. uniform current distribution is required for a stable operation of multiple parallel superconducting coils. In this paper, Rogowski coils were fabricated to measure each shunt current of a 4-parallel superconducting coil. Four Rogowski coils were installed at the copper bars, which are used as current leads in superconducting coils. As a result, linearity of the Rogowski coils was ascertained and coefficients of each coil, the ratio of voltage and current, were derived. The coefficients were compared with theoretically calculated values. Based on the coefficients, each shunt current was calculated in a 4-parallel superconducting coil, where uniform current. distribution was confirmed. This paper verified the feasibility of the fabricated Rogowski coils as well as operational stability of the 4-parallel superconducting coil in 77K.