• The Korean Journal of Applied Statistics
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• v.28 no.6
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• pp.1171-1180
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• 2015

Multidimensional scaling (MDS) is a graphical technique of multivariate analysis to display dissimilarities among individuals into low-dimensional space. We often have two kinds of MDS which are metric MDS and non-metric MDS. Metric MDS can be applied to quantitative data; however, we need additional information about variables because it only shows relationships among individuals. Gower (1992) proposed a method that can represent variable information using trajectories of the pseudo-points for quantitative variables on the metric MDS space. We will call his method a 'replacement method'. However, the trajectory can not be represented even though metric MDS can be applied to binary data when we apply his method to binary data. Therefore, we propose a method to represent information of binary variables using pseudo-points called a 'partition method'. The proposed method partitions pseudo-points, accounting both the rate of zeroes and ones. Our metric MDS using the proposed partition method can show the relationship between individuals and variables for binary data.

• The Korean Journal of Applied Statistics
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• v.21 no.1
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• pp.141-149
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• 2008

Recently we frequently analyze multivariate data with quite large number of variables. In such data sets, virtually duplicated variables may exist simultaneously even though they are conceptually distinguishable. Duplicate variables may cause problems such as the distortion of principal axes in principal component analysis and factor analysis and the distortion of the distances between observations, i.e. the input for cluster analysis. Also in supervised learning or regression analysis, duplicated explanatory variables often cause the instability of fitted models. Since real data analyses are aimed often at multiple purposes, it is necessary to reduce the number of variables to a parsimonious level. The aim of this paper is to propose a practical algorithm for selection of a subset of variables from a given set of p input variables, by the criterion of minimum trace of partial variances of unselected variables unexplained by selected variables. The usefulness of proposed method is demonstrated in visualizing the relationship between selected and unselected variables, in building a predictive model with very large number of independent variables, and in reducing the number of variables and purging/merging categories in categorical data.

• The Korean Journal of Applied Statistics
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• v.24 no.2
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• pp.411-424
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• 2011

The studies of congruence in organizational research have explored the concepts such as person-job fit person-organization fit, or person-environment fit. The relevant studies dealt with the fit level as an important influencing factor on the performance. In particular, researchers have agreed that employees can be motivated by the high level fit of person-organization. However, few research developing an alternative methodological approach has been done. For the purpose mentioned above the statistics like D, |D| or $D^2$ and the Q values such as Q(the correlation between two sets of interval measures) or $Q_r$(the correlation between two rankings) have been conventionally adopted in spite of numerous methodological problems. In general, these traditional indices such as difference scores, or Q values, are nondirectional and add an extra weight to differences of lager magnitude. Therefore, Edwards (1993) introduced the polynomial regression and the response surface analysis to overcome flaws with conventional approaches. However, the method-ological approaches did not reflect the profile characteristics of person-organizational value fit and wouldn't be a proper solution for the fit level of person-organization value maximizing performance. Hence, this paper investigates alternative methodological approaches, the multivariate polynomial regression and the multiple response surface analysis, to avoid the problems issued from conventional ways.

• Asian Pacific Journal of Cancer Prevention
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• v.15 no.7
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• pp.3233-3238
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• 2014

Background: The aim of this study was to analyze the demographic and clinical characteristics of male breast cancer patients in Serbia, and furthermore to determine overall survival and predictive factors for prognosis. Materials and Methods: In the period of 1996-2006 histopathological diagnosis of breast cancer was made in 84 males at the Institute for Oncology and Radiology of Serbia. For statistical analyses the Kaplan-Meier method, long-rank test and Cox proportional hazards regression model were used. Results: The mean age at diagnosis with breast cancer was $64.3{\pm}10.5$ years with a range from 35-84 years. Nearly 80% of the tumors showed ductal histology. About 44% had early tumor stages (I and II) whereas 46.4% and 9.5% of the male exhibitied stages III and IV, respectively. Only 7.1% of male patients were grade one. One-fifth of all patients had tumors measuring ${\leq}2cm$, and 14.3% larger than 5 cm. Lymph node metastasis was recorded in 40.4% patients and 47% relapse. Estrogen and progesterone receptor expression was positive in 66.7% and 58.3%, respectively. Among 14.3% of individuals tumor was HER2 positive. About two-thirds of all male patients had radical mastectomy (66.7%). Adjuvant hormonal (tamoxifene), systematic chemotherapy (CMF or FAC) and adjuvant radiotherapy were given to 59.5%, 35.7% and 29.8% patients respectively. Overall survival rates at five and ten years for male breast cancer were 55.0% and 43.9%, respectively. According to the multivariate Cox regression predictive model, a lower initial disease stage, a lower tumor grade, application of adjuvant hormone therapy and no relapse occurrence were significant independent predictors for good overall survival. Conclusions: Results of the treatment would be better if disease is discovered earlier and therefore health education and screening are an imperative in solving this problem.

• Korean Journal of Food Science and Technology
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• v.28 no.6
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• pp.1171-1176
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• 1996

The changes in volatiles of the model system were analyzed by GC and GC-MS before and after retorting. The GC data were analyzed statistically by applying the analysis of variance, and 42 peaks were selected at 5% significance level. Multivariate statistical analysis was performed with these 42 peaks as independent variables. Through the stepwise discriminant analysis, 8 peaks, which corresponded to the compounds such as 2-heptanone, cis-3-hexenal, 2-pentyl-furan, 1-methyl-trans-1,2-cyclohexanediol, 2-hexanone, 3-octanone, trans, trans-nona-2,4-dienal and 1-octen-3-ol, were obtained in sequence to distinguish the samples with and without retorting. The principal component analysis of a set of 8 independent variables resulted in 3 principal components which accounted for 96.1% of the variance, while the first principal component (PC 1) explained 76.5% of the total variance. In addition, through the factor analysis of the principal components, the peaks 11, 20 and 21 could be grouped togather in accordance with the direction and the size while the peaks 9, 33 and 39 constituted the second group in the direction.

• Journal of the Korean Chemical Society
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• v.31 no.6
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• pp.555-566
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• 1987

Fifty ancient Korean coins originated in Yi Dynasty have been determined for 9 elements such as Sn, Fe, As, Ag, Co, Sb, Ir, Ru and Ni by instrumental neutron activation analysis and for 3 elements such as Cu, Pb, and Zn by atomic absorption spectrometry. Bronze coins originated in early days of the dynasty contain as major constituents Cu, Pb and Sn approximately in the ratio 90 : 4 : 3, whereas, those in latter days contain in ratio 7 : 2 : 0. Brass coins which had begun in 17 century contain as major constituents Cu, Zn and Pb approximately in the ratio 7 : 1 : 1. The multivariate data have been analyzed for the relation among elemental contents through the variance-covariance matrix. The data have been further analyzed by a principal component mapping method. As the results training set of 8 class have been chosen, based on the spread of sample points in an eigen vector plot and archaeological data such as age and the office of minting. The training set and test set of samples have finally been analyzed for the assignment to certain classes or outliers through the statistical isolinear multiple component analysis (SIMCA).

• Journal of Soil and Groundwater Environment
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• v.13 no.6
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• pp.72-84
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• 2008

This study was carried out to provide proper management plans for small portable water supply system in the Nonsan area through water quality monitoring, hydrogeochemical investigation and multivariate statistical analyses. Nonsan area is a typical rural area heavily depending on small water supply system for portable usage. Geology of the area is composed of granite dominantly along with metasedimentary rocks, gneiss and volcanic rocks. The monitoring results of small portable water supply system showed that 13-21% of groundwaters have exceeded the groundwater standard for drinking water, which is 5 to 8 times higher than the results from the whole country survey (2.5% in average). The major components exceeding the standard limits are nitrate-nitrogen, turbidity, total coliform, bacteria, fluoride and arsenic. High nitrate contamination observed at southern and northern parts of the study area seems to be caused by cultivation practices such as greenhouses. Although Ca and $HCO_3$ are dominant species in groundwater, concentrations of Na, Cl and $NO_3$ have increased at the granitic area indicating anthropogenic contamination. The groundwaters are divided into 2 groups, granite and metasedimentary rock/gneiss areas, with the second principal component presenting anthropogenic pollution by cultivation and residence from the principal components analysis. The discriminant analysis, with an error of 5.56% between initial classification and prediction on geology, can explain more clearly the geochemical characteristics of groundwaters by geology than the principal components analysis. Based on the obtained results, it is considered that the multivariate statistical analysis can be used as an effective method to analyze the integrated hydrogeochemical characteristics and to clearly discriminate variations of the groundwater quality. The research results of small potable water supply system in the study area showed that the groundwater chemistry is determined by the mixed influence of land use, soil properties, and topography which are controlled by geology. To properly control and manage small water supply systems for central and local governments, it is recommended to construct a total database system for groundwater environment including geology, land use, and topography.

• Korean Journal of Applied Biomechanics
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• v.25 no.4
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• pp.401-412
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• 2015

Objective : The purpose of this study is to evaluate the effects of hip joint exercises and orthotics on RCSP, ankle's range of motion, and core muscle strength of middle school students with pes planus. Method : Out of the original pool of 200 students, 60 students with pes planus (RCSP < -2) were selected for the study. The selected 60 students were then divided into four groups. The first group was a combined orthotics and exercise group (12 students), the second was the orthotics-only group (9 students), the third was the exercise-only group (8 students), and the last was the control group (10 students). Exercise groups worked out twice a week for 60 minutes per session over 8 weeks. The independent variables were corrective hip joint exercises and orthotics. The dependant variables consisted of kinematic and kinetic variables. The kinematic variables were RCSP, and ankle's range of motion (dorsiflexion and plantarflexion). The kinetic variables were muscles forces that consist in core muscle strength, which are hip joint adduction, abduction, and flexion muscles forces. Statistical analysis was performed via SPSS 18.0 with multivariate analysis of covariance (MANCOVA) and a paired t-test was used. Results : The left foot was more responsive to the treatments, both exercise and orthotics, than the right foot. RCSP improved significantly in the left foot for the first and third groups. Only the first group significantly improved hip joint adduction, abduction, and flexion muscles' strengths. As for the ankle's range of motion of the left foot, plantarflexion showed improvement when treated with exercise, orthotics, or both. Conclusion : This study found that exercise is more effective in correcting RCSP and foot orthotics is more effective in reinforcing core muscle strength. Future studies should expand on these results to examine the relationship between the ankle, hip, and pelvis.

• Asian Pacific Journal of Cancer Prevention
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• v.15 no.9
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• pp.4079-4083
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• 2014

Background: Previous studies have showed that argonaute 2 is a potential factor related to genesis of several cancers, however, there have been no reports concerning gliomas. Methods: Paraffin specimens of 129 brain glioma cases were collected from a hospital affiliated to Binzhou Medical University from January 2008 to July 2013. We examined both argonaute 2 mRNA and protein expression by real-time quantitative PCR (qRT-PCR), Western blot analysis, and immunohistochemistry (IHC). The survival curves of the patients were determined using the Kaplan-Meier method and Cox regression, and the log-rank test was used for statistical evaluations. Results: Both argonaute 2 mRNA and protein were upregulated in high-grade when compared to low-grade tumor tissues. Multivariate analysis revealed that argonaute 2 protein expression was independently associated with the overall survival (HR=4.587, 95% CI: 3.001-6.993; P=0.002), and that argonaute 2 protein expression and WHO grading were independent prognostic factors for progression-free survival (HR=4.792, 95% CI: 3.993-5.672; P<0.001, and HR=2.109, 95% CI: 1.278-8.229; P=0.039, respectively). Kaplan-Meier analysis with the log-rank test indicated that high argonaute 2 protein expression had a significant impact on overall survival (P=0.0169) and progression-free survival (P=0.0324). Conclusions: The present study showed that argonaute 2 expression is up-regulated in gliomas. Argonaute 2 might also serve as a novel prognostic marker.

• Journal of Korean Neurosurgical Society
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• v.30 no.6
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• pp.761-768
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• 2001

Objective : To describe the underlying causes, surgical results, and prognostic factors in thoracic stenosis causing myelopathy, retrospective analysis for 28 cases of thoracic stenosis with surgery was performed Materials & Method : Twenty-eight patients(male, 15 ; female, 13) who underwent decompressive surgery for thoracic stenosis between 1987 and 1997 were analyzed. The mean age was 49 and the mean follow-up was 30.6 months. Statistical analysis with $SPSS^{(R)}$ was performed. Chi-square test was used for the analysis of relationship between subjects and multivariate analysis with general linear model was used to find prognostic factors. Result : Degenerative spondylosis was the most common cause, and three cases were associated with systemic diseases. Decompressive laminectomy was done in 23 cases, anterior decompression in four cases, and combined decompression in one case. Ossification of ligamentum flavum was found in 18 cases, facet hypertrophy in 13, ossification of posterior longitudinal ligament in six, and ventral spur in four. Postoperatively, 16 patients improved functionally and 4 patients worsened. The group of which initial symptom duration was less than two years showed better result(p=0.003). The group with sufficient decompression and no additional proximal stenosis had better outcome(p=0.002, p=0.001). Conclusion : Chronic myelopathy caused by thoracic stenosis can be reversible with appropriate decompression.