• Korean Journal Plant Pathology
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• v.13 no.1
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• pp.46-56
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• 1997

Based on the principal component analysis (PCA) of Richards' parameter estimates, ginseng field soils were grouped as the principal component 1 (PC1) and the principal component 2 (PC2). The microflora and physico-chemical characteristics of each soil group were compared to elucidate soil environmental factors affecting the disease development of root rot of ginseng seedling. Among 3 soil groups by PC1, there were differences in the populations of total fungi (TF) and Cylindrocarpon plus Fusarium (C+F), and the population ratio of Cylindrocarpon plus Fusarium to total fungi or total bacteria (C+F/TF, C+F/TB) in rhizoplane of ginseng seedlings, the population of total actinomycetes (TA) and the population ratio of total Fusarium to total actinomycetes (Fus/TA) in soil, and soil chemical properties (EC, NO3-N, K, Mn, ect.). Among 4 soil groups by PC2, there were differences in TF, C+F, TB, C+F/TF and C+F/TB in the rhizoplane, Trichoderma plus Gliocladium (T+G) in soil, and P2O5 content in soil. Especially, EC, NO3-N, K, K/Mg and Mn were positively correlated to PC1, and TA was negatively to PC1; however, TF, C+F, TB, C+F/TF and C+F/TB in the rhizoplane were significantly correlated to PC2 positively. On the other hand, microbes in the rhizoplane were not significantly correlated to the stand-missing rate (SMR), although TA and Fe/Mn were negatively correlated, and pH and Ca were positively correlated to SMR.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.8C
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• pp.771-776
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• 2006

We present a suboptimum decoding method for space-time trellis codes, which include maximum $likelihood(ML)^{[1]}$ and principal ratio $combining(PRC)^{[2]}$, over quasi-static flat fading channels. In the proposed scheme, the receive antennas are divided into K groups and the PRC is applied to each group, showing a flexible performances between ML and PRC. When K is determined, we also propose the optimum grouping rules and performance index(PI), which simply anticipate the relative performances. Moreover the performances are also evaluated when receive antennas are correlated. Finally, Computer simulations corroborate those theoretical results.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38B no.4
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• pp.257-265
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• 2013

In this paper, we proposed a Dynamic Channel Assignment (DCA) scheme called Graph Coloring based DCA (GC-DCA) to improve system performance for downlink femtocell networks with high density femto Access Point (AP) deployments. The proposed scheme consists of two steps: one is a femto AP grouping step considering interference and the other is a DCA step considering Signal to Interference plus Noise Ratio (SINR) for femto User Equipments (UEs). Simulation results show that the proposed GC-DCA outperforms other schemes in terms of the mean femto UE capacity and probability of femto UEs which have capacities less than a given transmit rate.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.44 no.12
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• pp.28-33
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• 2007

We present a space-time trellis coded OFDM system in flow fading channels. Generalized principal ratio combining (GPRC) is also analyzed theoretically in frequency domain. The analysis show that the decoding metric of GPRC include the metrics of maximum likelihood (ML) and PRC. The computer simulations with M-PSK modulation are obtained in frequency flat and frequency selective lading channels. The decoding complexity and simulation running times are also evaluated among the decoding schemes.

• Journal of Korea Society of Digital Industry and Information Management
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• v.14 no.3
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• pp.77-85
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• 2018

Multi-User Multiple-Input Multiple-Output (MU-MIMO) is the core technology for improving the channel capacity compared to Single-User MIMO (SU-MIMO) by using multiuser gain and spatial diversity. Key problem for the MU-MIMO is the user selection which is the grouping the users optimally. To solve this problem, we adopt Extreme Value Theory (EVT) at the beginning of the proposed algorithm, which defines a primary user set instead of a single user that has maximum channel power according to a predetermined threshold. Each user in the primary set is then paired with all of the users in the system to define user groups. By comparing these user groups, the group that produces a maximum sum rate can be determined. Through computer simulations, we have found that the proposed method outperforms the conventional technique yielding a sum rate that is 0.81 bps/Hz higher when the transmit signal to noise ratio (SNR) is 30 dB and the total number of users is 100.

• Journal of the Korea Safety Management & Science
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• v.7 no.5
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• pp.59-67
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• 2005

The main objective of the statistical analysis about industrial accidents is to find out what is the dangerous factor in its own industrial field so that it is possible to prevent or decrease the number of the possible accidents by educating those who work in the fields for safety tools. However, so far, there is no technique of quantitative evaluation on danger. Almost all previous researches as to industrial accidents have only relied on the frequency analysis such as the analysis of the constituent ratio on accidents. As an application of data mining technique, this paper presents analysis on the efficiency of the CHAID algorithm to classify types of industrial accidents data and thereby identifies potential weak points in accident risk grouping.

• Journal of the Korean Society of Clothing and Textiles
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• v.33 no.2
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• pp.230-243
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• 2009

The purpose of this study was to analyse the body sizes of $7{\sim}12$ years elementary school girls and also to categorize KS size dimensions by the detailed information of ages and body shapes. For the study, the data of SizeKorea(2004) was analysed. Height, bust, waist, hip, the ratio of waist to height and hip to height were significant between age groups, but the ratio of bust to height was not. Therefore, the increase of bust size was resulted in growth of bust circumference, instead of bust volume. In the same height group, over 11 year girls had smaller waist, while over 12 year girls had bigger hip. For Grouping girls by ages and body shapes, the ages were divided into 2 groups, under 10 years old and 11 to 12 years old. The body shapes classified into 3 groups 'Stout-shape', 'Middle-shape', and 'slim-shape', by the ratios of bust to height and hip to height. 'Stout-shape' was significantly big at the almost sizes, but 'Middle-shape' was significantly big at only circumferences, not lengths. In addition, drop(the difference between bust and hip) and lower-drop(the difference between waist and hip) were in inverse proportion to the ratios of bust to height and hip to height. It meant the increases of bust-ratio and hip-ratio of 'Stout-shape' were resulted in overweight, rather than female matureness. The distribution of sizes over 0.5% were grouped for grading system and the subtotal percentiles of each group were calculated for industrial data. The groups which covered more than 10% of consumers were 2 to 6 and the 1 or 2 groups for 'Stout-shape' were also observed, so that children's ready-to wear companies could use them efficiently for their own consumer target.

• Journal of Preventive Medicine and Public Health
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• v.34 no.4
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• pp.323-330
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• 2001

Objective : To examine the association between age at menopause and mortality in a population-based sample of women in Kangwha, Korea. Methods : From the Kangwha Cohort, followed-up from 1985 to 1999, the data of the over 55 year old female group(n=3,596) was used in this study to examine the association between age at menopause and mortality. We calculated the all causes mortality risk ratio and the cancer mortality risk ratio by age at menopause grouping using the Cox Proportional Hazards Model with adjustments for age, BMI, smoking, education, chronic disease, self-rated health status, alcohol consumption and age at first birth. Result and conclusion : Compared to women who had menopause at 45-49 years, the all causes mortality risk ratio was 1.24 for women with menopause at less than 40 years(95% CI=1.01-1.53) and 1.05 for women with menopause at over 50 years(95% CI=0.92-1.20). Also, compared to women who had menopause at 45-49 years, the cancer mortality risk ratio was 1.53 for women with menopause at less than 40 years(95% CI=0.78-2.98) and 1.17 for women with menopause at over 50 years(95% CI=0.77-1.80).

• Journal of KIISE:Software and Applications
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• v.34 no.1
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• pp.59-69
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• 2007

In the video with a various environment, background modeling is important for extraction and recognition the moving object. For this object recognition, many methods of the background modeling are proposed in a process of preprocess. Among these there is a Kumar method which represents the Queue-based background modeling. Because this has a fixed period of updating examination of the frame, there is a limit for various system. This paper use a background modeling based on the queue. We propose the method that major parameters are decided as adaptive by background model. They are the queue size of the sliding window, the sire of grouping by the brightness of the visual and the period of updating examination of the frame. In order to determine the factors, in every process, RCO (Ratio of Correct Object), REO (Ratio of Error Object) and UR (Update Ratio) are considered to be the standard of evaluation. The proposed method can improve the existing techniques of the background modeling which is unfit for the real-time processing and recognize the object more efficient.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.43 no.3 s.345
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• pp.1-9
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• 2006

In this paper, we propose a MIMO-OFDMA (Multi Input Multi Output-Orthogonal Frequency Division Multiple Access) system based on beamforming for performance improvement of downlink real-time traffic transmission in harsh channel conditions with low CIR (Carrier-to-Interference Ratio). In the proposed system, we first consider the M-GTA-SBA (Modified-Grouped Transmit Antenna-Simple Bit Allocation) using effective CSI (Channel State Information) calculation procedure based on spatial resource grouping, which is adequate for the combination of MRT (Maximum Ratio Transmission) in the transmitter and MRC (Maximum Ratio Combining) in the receiver. In addition, to reduce feedback information for the beamforming, we also apply QEGT (Quantized Equal Gain Transmission) based on quantization of amplitudes and phases of beam weights. Furthermore, considering multi-user environments, we propose the P-SRA (Proposed-Simple Resource Allocation) algorithm for fair and efficient resource allocation. Simulation results reveal that the proposed MIMO-OFDMA system achieves significant improvement of spectral efficiency in low CRI region as compared to a typical open-loop MIMO-OFDMA system using pseudo-orthogonal space time block code and H-ARQ IR (Hybrid-Automatic Repeat Request Incremental Redundancy).