• Journal of the Korean Data and Information Science Society
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• v.28 no.1
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• pp.67-74
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• 2017

This paper analyzes the causal relationship from climate to international grain prices. Although climate is an important factor affecting the grain markets, it has been restrictively considered in previous studies analyzing the causal relationship of international grain prices. In this paper, monthly data from May 1987 to 2013 is used for the causal analysis in which the sea surface temperature (SST), a representative global climate variable, and the international prices of wheat, corn, and soybean, the world's three major crops, are considered. The test method is the parametric version of the nonparametric test for causality in high-order moments suggested by Nishiyama et al. (2011). The results show that the climate causes in the first moment the prices of all the three grains and causes in the second moment the prices of corn and soybean, but does not cause in the third moment any of the three grain prices.

• Journal of the Korean Data and Information Science Society
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• v.28 no.1
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• pp.163-171
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• 2017

With the advance of function of smart phone system and internet services, mobile trade grows more popular in the area of e-business or banking. These environmental changes, it makes the needs of authorized certificates. Authorized certificate is not only important in these days but also future society. In 2015, 27 millions of Korean people used public key certificate, but most of them does not know the details on the public key certificate. Therefore, in this paper, we explain and investigate the characteristics on the public certificate and explain the relation ship between authorized certificate and public key encrytion. By investigating several papers, internet data, newspapers and books, we found the historical changes, substantial aspects, the encryption systems on the authorized certificate. Also we study the pros and cons of authorized certificate. Finally we predict the number of issued authorized certificate for the future society based on nonparametric statistical method.

• Journal of Yeungnam Medical Science
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• v.25 no.2
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• pp.108-116
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• 2008

Background : When surgeons plan mandible ortho surgery for patients with skeletal class III facial asymmetry, they must be consider the exact method of surgery for correction of the facial asymmetry. Three-dimensional (3D) CT imaging is efficient in depicting specific structures in the craniofacial area. It reproduces actual measurements by minimizing errors from patient movement and allows for image magnification. Due to the rapid development of digital image technology and the expansion of treatment range, rapid progress has been made in the study of three-dimensional facial skeleton analysis. The purpose of this study was to conduct 3D CT image comparisons of mandible changes after mandibular surgery in facial asymmetry patients. Materials & methods : This study included 7 patients who underwent 3D CT before and after correction of facial asymmetry in the oral and maxillofacial surgery department of Yeungnam University Hospital between August 2002 and November 2005. Patients included 2 males and 5 females, with ages ranging from 16 years to 30 years (average 21.4 years). Frontal CT images were obtained before and after surgery, and changes in mandible angle and length were measured. Results : When we compared the measurements obtained before and after mandibular surgery in facial asymmetry patients, correction of facial asymmetry was identified on the "after" images. The mean difference between the right and left mandibular angles before mandibular surgery was $7^{\circ}$, whereas after mandibular surgery it was $1.5^{\circ}$. The right and left mandibular length ratios subtracted from 1 was 0.114 before mandibular surgery, while it was 0.036 after mandibular surgery. The differences were analyzed using the nonparametric test and the Wilcoxon signed ranks test (p<0.05). Conclusion: The system that has been developed produces an accurate three-dimensional representation of the skull, upon which individualized surgery of the skull and jaws is easily performed. The system also permits accurate measurement and monitoring of postsurgical changes to the face and jaws through reproducible and noninvasive means.

• The Korean Journal of Applied Statistics
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• v.30 no.2
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• pp.259-269
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• 2017

Due to the nonnegativity of variance, most of nonparametric estimations of discontinuous variance function have used the Nadaraya-Watson estimation with residuals. By the modification of Chen et al. (2009) and Yu and Jones (2004), Huh (2014, 2016a) proposed the estimators of the log-variance function instead of the variance function using the local linear estimator which has no boundary effect. Huh (2016b) estimated the variance function using the adjusted squared residuals by the estimated jump size in the discontinuous variance function. In this paper, we propose an estimator of the discontinuous log-variance function using the local linear estimator with the adjusted log-squared residuals by the estimated jump size of log-variance function like Huh (2016b). The numerical work demonstrates the performance of the proposed method with simulated and real examples.

• The Journal of Advanced Prosthodontics
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• v.10 no.5
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• pp.347-353
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• 2018

PURPOSE. The purpose of this study was to evaluate the marginal discrepancy of heat-pressed ceramic veneers manufactured using a CAD/CAM system. MATERIALS AND METHODS. The ceramic veneers for the abutment of a maxillary left central incisor were designed using a CAD/CAM software program. Ten veneers using a microstereolithography apparatus (AM group), ten veneers using a five-axis milling machine (SM group), and ten veneers using a traditional free-hand wax technique (TW group) were prepared according to the respective manufacturing method. The ceramic veneers were also fabricated using a heat-press technique, and a silicone replica was used to measure their marginal discrepancy. The marginal discrepancies were measured using a digital microscope (${\times}160$ magnification). The data were analyzed using a nonparametric Kruskal-Wallis H test. Finally, post-hoc comparisons were conducted using Bonferroni-corrected Mann-Whitney U tests (${\alpha}=.05$). RESULTS. The $mean{\pm}SD$ of the total marginal discrepancy was $99.68{\pm}28.01{\mu}m$ for the AM group, $76.60{\pm}28.76{\mu}m$ for the SM group, and $83.08{\pm}39.74{\mu}m$ for the TW group. There were significant differences in the total marginal discrepancies of the ceramic veneers (P<.05). CONCLUSION. The SM group showed a better fit than the AM and TW groups. However, all values were within the clinical tolerance. Therefore, CAD/CAM manufacturing methods can replace the traditional free-hand wax technique.

• The Journal of the Korea Contents Association
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• v.10 no.5
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• pp.303-313
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• 2010

The purpose of this study is to evaluate the performance efficiency and productivity change of the regional public hospital in Korea. We use DEA(Data Envelopment Analysis) for CCR, BCC model, and MPI(Malmquist Productivity Index). DEA is a useful nonparametric technique for measurement of efficiency of a DMU(Decision Making Unit) and MPI is a evaluation method to measure DMU's productivity change. We utilize 34 regional public hospital's time-series data over 6 years from 2003 to 2008.The results of this study were as follows. First, technical efficiency(TE) shows that approximately 3.6% of inefficiency exists on the regional public hospitals and it reveals that the cause for technical inefficiency is due to scale inefficiency. Second, MPI's results show that regional public hospital made effort to improve total factor productivity change to raise technical efficiency. In order to raise efficiency, the regional public hospitals should deploy internal innovation and the government should support welfare policies.

• Journal of Wetlands Research
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• v.22 no.3
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• pp.178-186
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• 2020

In this study, the elasticity was calculated and sensitivity analysis was performed using air-water temperature data of the major tributaries of the Nakdong River. We developed a nonparametric elasticity analysis technique capable of estimating the confidence interval for elasticity and verifying the hypothesis, and examined its applicability compared to the existing method using the median value. It is analyzed that the elasticity of winter is low and the elasticity of summer and autumn is high, so that the fluctuation of water temperature and water quality according to the fluctuation of air temperature is large. The spatial elasticity tends to be low in the Geumho River area, which is influenced by artificial factors such as sewage treatment plant effluent, small and medium-sized livestock wastewater, and small-scale factory wastewater. Since the elasticity of major tributaries of the Nakdong River is over weak and is reasonable at a significance level of 5%, it was analyzed that the air-water temperature fluctuation caused by climate changes is large.

• The Korean Journal of Pain
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• v.10 no.2
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• pp.214-219
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• 1997

Background: Epidural neural blockade with local anesthetics combined with steroids has been in clinical trials for patients with low back pain. But pain treatment of low back pain remains somewhat problematic. Many patients with low back pain have epidural fibrosis and adhesions proved with magnetic resonance imaging(MRI) examination. These findings might play an important role in the origin of back pain. Present study was aims to investigate the effect of epidural adhesiolysis in patients with low back pain. Methods: We investigated 76 patients suspected with epidural fibrosis and adhesion was suspected. Nerve pathology was demonstrated and epidural fibrosis suspected or proved with MRI examination. 17G needle specially designed by Racz was inserted at sacral hiatus and catheter was inserted untill its tip was located at lesion site under fluoroscopic guidance. Injection of contrast dye was achieved and prospected spread of agents. Injection of 0.25% bupivacaine, triamcinolone, and 10% hypertonic saline via catheter were carried out daily for 3 days. Evaluation included assessment of pain relief (Numerical Rating Scale; NRS) post-epidural adhesiolysis 3 days, 1 week, and 3 months. We also looked for complication of epidural adhesiolysis. Results: Statistical analysis(Friedman nonparametric repeated measures test and Dune's multiple comparison test) demonstrated NRS was significantly less during 3 months after epidural adhesiolysis(P<0.05). Especially, there is a extremely significance in post-epidural adhesiolysis 3 days (P<0.001). Only four patients reported any complications the most common symptom among three persistent headache but disappeared after a few months without residual sequelae. Conclusion: We conclude epidural adhesiolysis is a safe and effective method of pain therapy for low back pain with proven lumbo-sacral fibrosis and adhesion. A direct visualization by epiduroscopy may be more useful to the resulting functional changes after epidural adhesiolysis.

• KIISE Transactions on Computing Practices
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• v.21 no.1
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• pp.94-99
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• 2015

With the recent machine learning paradigm of using nonparametric Bayesian statistics and statistical inference based on random sampling, the Dirichlet distribution finds many uses in a variety of graphical models. It is a multivariate generalization of the gamma distribution and is defined on a continuous (K-1)-simplex. This paper presents a sampling method for a Dirichlet distribution for the problem of dividing an integer X into a sequence of K integers which sum to X. The target samples in our problem are all positive integer vectors when multiplied by a given X. They must be sampled from the correspondingly gridded simplex. In this paper we develop a Markov Chain Monte Carlo (MCMC) proposal distribution for the neighborhood grid points on the simplex and then present the complete algorithm based on the Metropolis-Hastings algorithm. The proposed algorithm can be used for the Markov model, HMM, and Semi-Markov model for accurate state-duration modeling. It can also be used for the Gamma-Dirichlet HMM to model q the global-local duration distributions.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.40 no.4
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• pp.260-267
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• 2017

Quantum-inspired Genetic Algorithm (QGA) is a probabilistic search optimization method combined quantum computation and genetic algorithm. In QGA, the chromosomes are encoded by qubits and are updated by quantum rotation gates, which can achieve a genetic search. Asset-based weapon target assignment (WTA) problem can be described as an optimization problem in which the defenders assign the weapons to hostile targets in order to maximize the value of a group of surviving assets threatened by the targets. It has already been proven that the WTA problem is NP-complete. In this study, we propose a QGA and a hybrid-QGA to solve an asset-based WTA problem. In the proposed QGA, a set of probabilistic superposition of qubits are coded and collapsed into a target number. Q-gate updating strategy is also used for search guidance. The hybrid-QGA is generated by incorporating both the random search capability of QGA and the evolution capability of genetic algorithm (GA). To observe the performance of each algorithm, we construct three synthetic WTA problems and check how each algorithm works on them. Simulation results show that all of the algorithm have good quality of solutions. Since the difference among mean resulting value is within 2%, we run the nonparametric pairwise Wilcoxon rank sum test for testing the equality of the means among the results. The Wilcoxon test reveals that GA has better quality than the others. In contrast, the simulation results indicate that hybrid-QGA and QGA is much faster than GA for the production of the same number of generations.