• Journal of Communications and Networks
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• v.18 no.2
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• pp.238-245
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• 2016

A sequence number checking technique is proposed to improve the performance of TCP connections in mobile ad hoc networks. While a TCP connection is initialized, a routing protocol takes the responsibility for checking the hop count between a source and destination pair. If the hop count is greater than a predefined value, the routing protocol decides to use a proxy node. The responsibility of a proxy node is to check the correctness of data packets and inform the missing packets by sending an acknowledgement from a proxy node to the source node. By doing so, the source node is able to retransmit any missing packet in advance without waiting until an end-to-end acknowledgement is received from the destination. Simulation results show that the proposed mechanism is able to increase throughput up to 55% in static network and decrease routing overhead up to 95%in mobile network.

• Journal of the Korean Mathematical Society
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• v.61 no.3
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• pp.427-444
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• 2024

The matrix completion problem is to predict missing entries of a data matrix using the low-rank approximation of the observed entries. Typical approaches to matrix completion problem often rely on thresholding the singular values of the data matrix. However, these approaches have some limitations. In particular, a discontinuity is present near the thresholding value, and the thresholding value must be manually selected. To overcome these difficulties, we propose a shrinkage and thresholding function that smoothly thresholds the singular values to obtain more accurate and robust estimation of the data matrix. Furthermore, the proposed function is differentiable so that the thresholding values can be adaptively calculated during the iterations using Stein unbiased risk estimate. The experimental results demonstrate that the proposed algorithm yields a more accurate estimation with a faster execution than other matrix completion algorithms in image inpainting problems.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.1
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• pp.696-701
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• 2017

This paper proposes an improved de-interlacing method that converts interlaced images into progressive images from one field. First, it calculates inter-pixel values applying third-order spline interpolation for the horizontal direction from four upper lower pixel values of missing pixels. From inter-pixel values obtained from spline interpolation and upper lower pixels with value, the proposed method makes an accurate estimate of the direction by applying the correlation between upper and lower pixels. The correlation between upper and lower pixels is calculated in nine directions of a missing pixel by using values obtained from spline interpolation and pixels with value. The direction of an edge is determined as the direction in which the correlation between upper and lower pixels is at its minimum. Thus, a missing pixel is calculated by taking the average of upper lower pixels obtained from the predicted direction of an edge. From the simulation results, there are problems in that it takes a bit more time for processing, but it is expected that the time problem will be improved by increasing CPU processing speed. As for image quality, it is shown that the proposed method improves both subjective and objective image quality and quantitatively improves picture signal-to-noise ratio (PSNR) in the range between 0.1 dB to 0.5 dB, as compared with previously presented de-interlacing methods.

• Journal of Educational Research in Mathematics
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• v.18 no.1
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• pp.103-121
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• 2008

The primary purpose of this study was to gather knowledge about $5^{th},\;6^{th},\;and\;7^{th}$ graders' proportional reasoning ability by investigating their reactions and use of strategies when encounting proportional or nonproportional problems, and then to raise issues concerning instructional methods related to proportion. A descriptive study through pencil-and-paper tests was conducted. The tests consisted of 12 questions, which included 8 proportional questions and 4 nonproportional questions. The following conclusions were drawn from the results obtained in this study. First, for a deeper understanding of the ratio, textbooks should treat numerical comparison problems and qualitative prediction and comparison problems together with missing-value problems. Second, when solving missing-value problems, students correctly answered direct-proportion questions but failed to correctly answer inverse-proportion questions. This result highlights the need for a more intensive curriculum to handle inverse-proportion. In particular, students need to experience inverse-relationships more often. Third, qualitative reasoning tends to be a more general norm than quantitative reasoning. Moreover, the former could be the cornerstone of proportional reasoning, and for this reason, qualitative reasoning should be emphasized before proportional reasoning. Forth, when dealing with nonproportional problems about 34% of students made proportional errors because they focused on numerical structure instead of comprehending the overall relationship. In order to overcome such errors, qualitative reasoning should be emphasized. Before solving proportional problems, students must be enriched by experiences that include dealing with direct and inverse proportion problems as well as nonproportional situational problems. This will result in the ability to accurately recognize a proportional situation.

• Journal of Korea Water Resources Association
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• v.48 no.4
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• pp.245-255
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• 2015

This study used high density network of integrated meteorological sensor, which are operated by SK Planet, with KMA weather stations to estimate the quantitative precipitation field in Seoul area. We introduced SK Planet network and analyzed quality of the observed data for 3 months data from 1 July to 30 September 2013. As the quality analysis result, we checked most SK Planet stations observed similar with previous KMA stations. We developed the real-time quality check and adjustment method to reduce the error effect for hydrological application by missing and outlier value and we confirmed the developed method can be corrected the missing and outlier value. Through this method, we used the 190 stations(KMA 34 stations, SK Planet 156 stations) that missing ratio is less than 20% and the effect of the outlier was the smallest for quantitative precipitation estimation. Moreover, we evaluated reproducibility of rainfall field high density rain gauge network has $3km^2$/gauge. As the result, the spatial relative frequency of rainfall field using SK Planet and KMA stations is similar with radar rainfall field. And, it supplement the blank of KMA observation network. Especially, through this research we will take advantage of the density of the network to estimate rainfall field which can be considered as a very good approximation of the true value.

• Journal of Periodontal and Implant Science
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• v.23 no.1
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• pp.27-36
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• 1993

The purpose of the this study was to research the interrelationship of periodontal status and patient's age between diabetic group and non-diabetic group and compare that of periodontal status according to the blood sugar level and duration of diabetics. The participants of this study were 52 diabetic patients and 51 non-diabetic patients. The diabetic group and non-diabetic group were further divided into four subgroups according to the age(under 35 years old, 36 - 45 years old, 46 - 55 years old, over 56 years old) and the diabetic group was further divided into three subgroups according to the duration of diabetics (under 5 years, 6 - 10 years, over 11 years) and blood sugar level(under 140mg/100ml, 140-200mg/100ml, over 200mg /100ml), respectively. Author evaluated such periodontal status as plaque index and calculus index, gingival lndex, loss of attachment, papillary bleeding index, tooth mobility and missing teeth, and then data was statistically analyzed by SPSS/PC+ using ANOVA, respectively. The results were as follows: 1. The mean value of plaque index, gingival index, loss of attachment, papillary bleeding index, tooth mobility and missing teeth of diabetic patients were significantly higher than that of non-diabetic patients, respectively(p <0.01, p<0.01, p<0.01, p<0.01, p<0.001, p<0.001), but there was no significant difference between diabetic group and non-diabetic group in calculus index(P>0.05). 2. According to the increase of age, loss of attachment and missing teeth were increased in both group, and correlation of each subgroup was statistically significant, respectively(p<0.05, p<0.001). 3. According to the elevation of blood sugar level of diabetics, plaque index, gingival index, loss of attachment, papillary bleeding index, tooth mobility and missing teeth were increased in diabetic group, and correlation of each subgroup was statistically significant, respectively (p<0.05, p<0.05, p<0.05, p<0.05, p<0.001, p<0.001). 4. According to the duration of diabetics, plaque index, gingival index, loss of attachment, papillary bleeding index, tooth mobility and missing teeth were increased in diabetic group, and correlation of each subgroup was statistically significant, respectively(p<0.05, p<0.05, p<0.05, p<0.05, p<0.001, p<0.001).

• Fashion & Textile Research Journal
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• v.9 no.2
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• pp.229-236
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• 2007

Many researchers have focused on consumers' clothes purchase behavior, These researches could not reflect the characteristics of the single consumers' clothes purchase behavior. In addition, little has been written on the single consumer. The purposes of this study are to identify the concept and psychologic characteristics of single consumer and investigate the effects of single consumers' psychologic characteristic and susceptibility to interpersonal influence on clothes shopping pursuing value. Also, It was analyzed how single consumer' pursuing values are different based on the type of single motivation. To test research problems, Data were collected by means of a survey questionnaire, which was sent to 300 single in Pusan and Ulsan. In total, 274 were returned and 14 were unusable because of unacceptable levels of missing data. The Results were summarized as follows: First, self-efficacy, informative and normative influence were positively related to utilitarian pursuing value employee satisfaction. Also, self-efficacy, variety seeking, innovativeness and informative influence had a positive effect on hedonic pursuing value. Second, voluntary single and nonvoluntary single group had different perceptions about self-efficacy, variety seeking, innovativeness, informative influence, and hedonic pursuing value.

• Journal of the Korean Society of Clothing and Textiles
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• v.30 no.7 s.155
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• pp.1160-1167
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• 2006

The most ideal textile conservation is to block oxygen and light from historical textiles. However it is not possible because historical textiles should be examined, cleaned, restored, and exhibited to find out its historical value. Most of excavated costumes were severely stained and soiled. They are dark yellowish brown in color. To reduce the extent and intensity of the staining and to recover the original color of gray fabrics, bleaching would be required. Conservation treatment was carried out on the 8 historical costumes which belonged to General Duk-Ryung Kim(1567-1596). Two of them do not hold the fabrics. They hold only cotton wool and a little piece of fabrics. Even though these costumes underwent the conservation treatment in 1979, they were stained and needed re-treatment. This time, they were dual-bleached using hydrogen peroxide and sodiumborohydride followed by wet cleaning to reduce the soils and stains. The treatments improved the appearance of costumes. Through the analysis of the trace of fabric, carbonized fabric fragment, and fabrics remained in other garments, we concluded the missing fabrics to be ramie or cotton. It is different result from the primary report concluded to be silk.

• Asian-Australasian Journal of Animal Sciences
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• v.28 no.11
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• pp.1551-1557
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• 2015

The missing heritability has been a major problem in the analysis of best linear unbiased prediction (BLUP). We introduced the traditional genome-wide association study (GWAS) into the BLUP to improve the heritability estimation. We analyzed eight pork quality traits of the Berkshire breeds using GWAS and BLUP. GWAS detects the putative quantitative trait loci regions given traits. The single nucleotide polymorphisms (SNPs) were obtained using GWAS results with p value <0.01. BLUP analyzed with significant SNPs was much more accurate than that with total genotyped SNPs in terms of narrow-sense heritability. It implies that genomic estimated breeding values (GEBVs) of pork quality traits can be calculated by BLUP via GWAS. The GWAS model was the linear regression using PLINK and BLUP model was the G-BLUP and SNP-GBLUP. The SNP-GBLUP uses SNP-SNP relationship matrix. The BLUP analysis using preprocessing of GWAS can be one of the possible alternatives of solving the missing heritability problem and it can provide alternative BLUP method which can find more accurate GEBVs.

• Journal of The Korean Society of Agricultural Engineers
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• v.60 no.3
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• pp.15-25
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• 2018

Estimating the reference evapotranspiration is an important factor to consider in irrigation system design and agricultural water use. However, there is a limitation in using the FAO Penman-Monteith (FAO P-M) equation, which requires various meteorological data. The purpose of this study is to compare three reference evapotranspiration (ETo) equations in the case of meteorological data missing for 11 study weather stations. Firstly, the FAO P-M equation is used for reference potential evapotranspiration estimation with the actual solar radiation data $R_n$ and the actual vapor pressure $e_a$. Then, in the case of $R_n$, and $e_a$ are missed, the reference evapotranspirations applying FAO P-M, Priestley-Taylor (P-T), Hargreaves (HG) equation were calculated using other meteorological factors. Secondly, MAE, RMSE, $R^2$ were calculated to compare ETo relationship from the ETo equations. From the results, ETo with Hargreaves equation in coastal areas and the Priestley-Taylor equation in the inland areas showed relatively high correlation with FAO P-M when $e_a$ data is missed. In the case of $R_n$ data is missed or two weather data, $e_a$, and $R_n$ data are all missed, $R^2$ value in Priestley-Taylor equation was highest in coastal areas, and $R^2$ values in Hargreaves equation were the high values for 7 inland areas. The results of sensitivity analysis showed that net radiation was the most sensitive for P-T and HG equation, and for FAO P-M, the most sensitive factor was net radiation and relative humidity, air temperature and wind speed were follows. Therefore, in considering of the accessibility to the coast, the types of the missing wether data, and the correlation and the magnitude of error, the reference evapotranspiration equations would be selected in sense of different conditions.