• Communications for Statistical Applications and Methods
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• v.29 no.4
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• pp.453-469
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• 2022

The study of immune cellular composition has been of great scientific interest in immunology because of the generation of multiple large-scale data. From the statistical point of view, such immune cellular data should be treated as compositional. In compositional data, each element is positive, and all the elements sum to a constant, which can be set to one in general. Standard statistical methods are not directly applicable for the analysis of compositional data because they do not appropriately handle correlations between the compositional elements. In this paper, we review statistical methods for compositional data analysis and illustrate them in the context of immunology. Specifically, we focus on regression analyses using log-ratio transformations and the alternative approach using Dirichlet regression analysis, discuss their theoretical foundations, and illustrate their applications with immune cellular fraction data generated from colorectal cancer patients.

• Korean Journal of Remote Sensing
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• v.27 no.2
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• pp.151-161
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• 2011

PGA(Phase Gradient Autofocus) is a representative autofocus technique to improve the SAR(Synthetic Aperture Radar) image quality. PGA can estimate high order phase errors and have good robustness in noisy environments. However, PGA is not suitable to apply to the stripmap mode data directly because it is based on the spotlight mode operation. In this paper, the PGA implementation technique for stripmap mode data and the method of ROI(Region of Interest) selection that affects severely on PGA performance have been proposed. The proposed technique was verified by the point target simulation first, and was applied to the real SAR signal data acquired by the flight test. Finally, the significant improvements in focusing quality were shown in the processed SAR images using the proposed method.

• ETRI Journal
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• v.33 no.4
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• pp.517-527
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• 2011

Currently, there is a considerable interest in 3D object reconstruction using terrestrial laser scanner (TLS) systems due to their ability to automatically generate a considerable amount of points in a very short time. To fully map an object, multiple scans are captured. The different scans need to be registered with the help of the point cloud in the overlap regions. To guarantee reliable registration, the scans should have large overlap ratio with good geometry for the estimation of the transformation parameters among these scans. The objective of this paper is to propose a registration method that relaxes/eliminates the overlap requirement through the utilization of photogrammetrically reconstructed features. More specifically, a point-based procedure, which utilizes non-conjugate points along corresponding linear features from photogrammetric and TLS data, will be used for the registration. The non-correspondence of the selected points along the linear features is compensated for by artificially modifying their weight matrices. The paper presents experimental results from simulated and real datasets to illustrate the feasibility of the proposed procedure.

• The Korean Journal of Applied Statistics
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• v.11 no.1
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• pp.163-175
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• 1998

The change of hazard rates at some unknown time point has been the interest of many statisticians. But it was restricted to the constant hazard rates which correspond to the exponential distribution. In this paper we generalize the change-point model in which any specific functional forms of hazard rates are net assumed. The assumed model includes various types of changes before and after the unknown time point. The Nelson estimator of cumulative hazard function is introduced. We estimate the change-point maximizing slope changes of Nelson estimator. Consistency and asymptotic distribution of bootstrap estimator are obtained using the martingale theory. Through a Monte Carlo study we check the performance of the proposed method. We also explain the proposed method using the Stanford Heart Transplant Data set.

• Communications for Statistical Applications and Methods
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• v.21 no.6
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• pp.521-528
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• 2014

A stochastic Gompertz diffusion model for tumor growth is a topic of active interest as cancer is a leading cause of death in Korea. The direct maximum likelihood estimation of stochastic differential equations would be possible based on the continuous path likelihood on condition that a continuous sample path of the process is recorded over the interval. This likelihood is useful in providing a basis for the so-called continuous record or infill likelihood function and infill asymptotic. In practice, we do not have fully continuous data except a few special cases. As a result, the exact ML method is not applicable. In this paper we proposed a method of parameter estimation of stochastic Gompertz differential equation via Markov chain Monte Carlo methods that is applicable for several data structures. We compared a Markov transition data structure with a data structure that have an initial point.

• Journal of Advanced Navigation Technology
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• v.27 no.4
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• pp.481-487
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• 2023

Recently, interest in UAM (Urban Air Mobility) has surged as a critical solution to urban traffic congestion and air pollution issues. However, efficient UAM operation requires accurate 3D Point Cloud data processing, particularly in separating the ground and objects. This paper proposes and validates a method for effectively separating ground and objects in a UAM environment, taking into account its dynamic and complex characteristics. Our approach combines attitude information from MEMS sensors with ground plane estimation using RANSAC, allowing for ground/object separation that isless affected by GPS errors. Simulation results demonstrate that this method effectively operates in UAM settings, marking a significant step toward enhancing safety and efficiency in urban air mobility. Future research will focus on improving the accuracy of this algorithm, evaluating its performance in various UAM scenarios, and proceeding with actual drone tests.

• Journal of the Korean Society of Clothing and Textiles
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• v.27 no.2
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• pp.239-249
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• 2003

The purpose of this research was to investigate influential factors for shopmaster's CRM (Customer Relationship Management) in the designer brand products, and to indicate the future fashion marketing strategies. The questionnaires were distributed to 74 shopmasters of the Designer shop in domestic L. S and H Department stores. Descriptive statistics, factor analysis, and path analysis from Lisrel program were used to analyze the data. The results were as follows; Firstly. for shopmaster's CRM variables, four factors of customer management variables were found and labeled as interest, DB construction, contact opportunity, and materials. Also, four (actors of shopmaster's knowledge regarding apparel materials were found and labeled as professionalism, manner, sense, and persuasion. For service variables, four factors such as precision, variety, rapidity, positiveness, and convenience of shopping were found. Secondly, for the results of hypothesis, all of the independent variables had direct influences on forming the relationship with customers. Therefore, it is concluded that the main elements of Shopmaster's CRM are highly important variables in customer relationship marketing strategy.

• Journal of applied mathematics & informatics
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• v.23 no.1_2
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• pp.563-570
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• 2007

There has been a considerable research interest in medical communities for neuronal fiber tracking with magnetic resonance diffusion tensor imaging(DTI). DTI data have abundant structural boundaries that need to be preserved during interpolation to facilitate fiber tracking. Sigmoid function has been used in recent papers but the sigmoid function still is not good enough to be served as an positive interpolation in mathematical point of view. In this paper, we construct and provide two families positive cardinal interpolation functions.

• Research in Community and Public Health Nursing
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• v.15 no.3
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• pp.408-418
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• 2004

This study aims to provide useful basic materials for planning the Health Improvement Program and Policy for men aged 20 40. This study investigated 889 subjects, and at each corresponding age, who were collected among the trainers at the Civil Defense Training Institute in K-ku, Incheon City. The data collection period lasted from April to July of 2003. I revised and complemented the measurement tool for the Health Improvement Life Style developed by Jung Eun-Kyung. For analysis of the acquired data. I used SPSS11.0 program. The study shows that the Health Improvement Action of a group of middle aged men averaged 2.80, and 0.44 point out of 5. According to the results found during the analysis of the generic characters of differences in behaviors of Health Improvement. It was revealed that there were significant differences in age, regular exercise and health interest, stress management, self-concept as well as degrees of interest in health, and education level. According to monthly income levels, regular exercise and degrees of self-concept degrees were significantly different from each other. According to marital status. balanced diet and regular exercise were related to each other. According to religion, balanced diet, stress management degree, self concept degree, and degrees of interest in health, significant differences were shown. Based on the earlier mentioned results, we should pay attention to act more, rather than merely recognize the development of the health improvement program of our regional community. Also, it is necessary to find out the cause, which lowers men's interest in health.

• Proceedings of the KSRS Conference
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• 2004.10a
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• pp.256-259
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• 2004

Recently, Location-based services(LBS) allow consumers to receive services based on their geographic location data. Users want to take services based location information with portable devices. And Point of Interest(POI) information's usage is increasing with mobile device's development and user's interest. And this paper shows that we connect the multimedia POI database(DB), provide the multimedia services through the portable devices and search POI using location and direction information. The multimedia POI is consisted of sound, image, moving image and animation with location information. When we search POI, we find POI in DB using the area zone and direction information.[l]