그리드 데이터베이스에서 동적 계층 구조를 이용한 부하 분산 기법

서윤석 김천과학대학 2009 김천과학대학 논문집 Vol.35 No.-

This paper suggests a reallocation method based on dynamic hierarchical structure to solve the problems with reallocation in the proximity The method suggested in this study dynamically creates reallocation manager that collects information of each database at the time of reallocation in a logical way. In addition, by forming reallocation manager on the basis of hierarchical structure, it supports stepwise dispatch of information and reallocation algorithm, which, in turn, enables support of local reallocation algorithm and efficient balance adjustment. In this method, quicker processing is possible by distributing the burden of the uppermost reallocation manager to collect and analyze all the information to lower level reallocation manager using summarized information at the time of performing reallocation algorithm. This method is found to contribute to the increase in total processing volume after reallocation via performance evaluation.

공간 데이터 웨어하우스에서 공간적 의사 결정을 위한 데이터 큐브 색인 기법

서윤석 김천과학대학 2010 김천과학대학 논문집 Vol.36 No.-

Most decision support functions of spatial data warehouse rely on OLAP operations upon a spatial cube. Meanwhile, higher performance is always guaranteed by indexing the cube, which stores huge amount of pre-aggregated information. Hierarchical Dwarf was proposed as a solution, which can be taken as an extension of the Dwarf, a compressed index for cube structures, However, it does not consider the spatial dimension and even aggregates incorrectly if there are redundant values at the lower levels. OLAP-favored Searching was proposed as a spatial hierarchy based OLAP operation, which employs the advantages of R-tree. Although is supports aggregating functions well against specified areas, it ignores the operations on the aspatial dimension. In this paper, an indexing approach, which aims at utilizing the concept hierarchy of the spatial cube for decision support, is proposed. The index consists of concept hierarchy trees of all dimensions, which are linked according to the tuples stored in the fact table. It saves storage cost by preventing identical trees from being created redundantly, Also, it reduces the OLAP operation cost by integrating the spatial and aspatial dimension in the virtual concept hierarchy.

u-GIS 환경에서 지오센서 데이터 스트림의 효과적인 처리를 위한 GS-DSMS의 설계

서윤석 김천과학대학 2011 김천과학대학 논문집 Vol.37 No.-

In u-GIS environments, GeoSensor generates sensor data streams including spatial information as well as various conventional sensor data from RFID, WSN, Web CAM, Digital Camera, CCTV, and Telematics units. This GeoSensor enables the revitalization of various ubiquitous USN technologies and services on geographic information. In order to service the u-GIS applications based on GeoSensors, it is indispensable to efficiently process sensor data streams from GeoSensors of a wide area. In this paper, we propose a GeoSensor data stream processing system for u-GIS computing over real-time stream data from GeoSensors with geographic information. The proposed system provides efficient gathering, storing, and continuous query processing of GeoSensor data stream, and also makes it possible to develop diverse u-GIS applications meet each user requirements effectively.

공간 데이터에서 시공간 데이터의 효율적인 집계 연산

서윤석 김천과학대학 2005 김천과학대학 논문집 Vol.31 No.-

Recently, the data that is simply summarized from spatial data warehouses is required. Aggregate operation can be obtained from spatial data warehouses directly whenever it is needed, but it costs lots of time. Thus pre-aggregation is required for the efficient OLAP(On-Line Analytical Processing) operation. There are two kinds of spatiotemporal data: current and past data. Previous studies, which manage the pre-aggregate information from spatial data warehouses, provide only one type of pre-aggregate information, so previous studies can not provide real time responses when the current and past data are queried frequently. Also, the method that gives only past aggregate information can not supply the OLAP operation by time dimension because it can not maintain the historical information. In this thesis, method that can manage the pre-aggregate information of current and past spatiotemporal data efficiently is proposed. The proposed method maintains current aggregate information by aR-tree and keeps historically summarized aggregate information by HISAT(Historically Summarized Aggregate Table) at the same time.

실시간 공간 데이터베이스 시스템을 위한 질의 최적화 기법

서윤석 김천과학대학 2003 김천과학대학 논문집 Vol.29 No.-

Real-time spatial database application systems require that spatial data have to be updated within valid time and user queries should be processed in real-time. In these systems, it needs to be considered a processing about real-time spatial data and real-time spatial query they are not considered in a conventional spatial database application systems. Real-time spatial queries in real-time spatial database application systems are hard to be processed successfully, because spatial operation takes major time in total processing and its real-time spatial data are easy to miss their validity. Therefore, it is required a query processing technique that makes queries meet time constraints of real-time spatial query with keeping validity of real-time spatial data. real-time operation post-placing technique is proposed in order to meet time constraints of real-time data and queries in real-time spatial query processing with managing real-tome spatial data and considering that manages real-time spatial data used in real-time spatial query.

완전 직장탈 환자에서 변실금에 영향을 미치는 인자

윤서구,이광렬,김건욱,송석규,김칠석,이종균,김광연 대한대장항문학회 2001 Annals of Coloproctolgy Vol.17 No.1

경남 고성군 덕명리 상족암지역의 야외지질학습자료 개발 및 활용에 관한 연구

서석근,윤성효 부산대학교 사범대학 과학교육연구소 2001 科學敎育硏究報 Vol.28 No.-

In the recent years, the importance of experience learning has been emphasized in the science education. Because of this situation, the science education that was mainly taught in the class has been changed into the field work. Therefore, the related teachers have recognized the systematic necessities of teaching materials that will be focused on the teaching places and activities. This study seeks to develop the study materials for the field geologic practice in the Snagjok-am, Deokmyeong-ri, Goseong-gun, Gyeonsangname-do, and to find the teaching methods for the geologic units of the earth science at the middle school. There are wide outcrop of sedimentary rocks which eroded by the sea waves in this place. And we have easily access to that place, so the field observation can be carried out successfully. Also there are various rocks, geologic structures, and fossils which are the importance materials for the science curriculum at the middle school. The practice course is divided into from A to E courses, and the related materials are made for the purpose of investigating those whole sites within one or two days. Each course can be explained as the followings. (1) Course A: participants can study from three stops the joint system of igneous rocks, the bedding layer of the sedimentary rocks, and the various characteristics of the shore sediments. (2) Course B: participants can investigate from three stops the structure of the sedimentary rocks, that is cross bedding, sun cracks and fossils. (3) Course C: participants can survey from two stops the various rock facies and geologic structure caused from the intrusion of igneous rocks. (4) Course D: in this course, students can observe the various aspects spontaneously because the previously stated geologic structures are repeatedly appeared. (5) Course E: participants can study the wave0cut bench, cliffs, and caves caused by the erosion of sea waves. This thesis seeks to develop the geologic informations, learning content, instructive and teaching methods, background knowledge, and the materials of field studies which students can effectively used. The content of field studies have focus on the geologic unit at the middle school science textbook, but this can be varied flexibly according to the related levels. Additionally, this study has been proven practically through the real experiments conducted by the first class student of the middle school. The conclusion is that the field programs have had the affirmative result in improving the scientific attitudes, and the cognition about field works has been appraised positively.

공간 데이터베이스에서 확장된 R-Tree를 이용한 효율적인 공간 질의 처리

서윤석 김천과학대학 2004 김천과학대학 논문집 Vol.30 No.-

R-Tree provides indirect access path to spatial object by using MBR(Minimum Boundary Rectangle). Various kind of object approximation method has been proposed, but most of them has low filtering performance. MBR decomposition methods has been proposed to upgrade filtering performance but it has disadvantage when object is very complex because it require large size of additional space to store decomposed MBR. Another solution to solve low performance of filter step in R-Tree is object decomposition method. It has good filtering performance but when information on original object is needed, object has to be reconstructed. In this thesis, we proposed extended R-Tree which has grid for secondary filter. Girds consist of cells which store information on original object. Each cells represents whether any part of original object is existed in cell boundary or not. Proposed method requires relatively small amount of space, and it provides easy way of inspection.

그리드 데이터베이스에서 질의 처리 최적화 기법

서윤석 김천과학대학 2008 김천과학대학 논문집 Vol.34 No.-

In this pager, a method of query processing optimization in the grid database is proposed. To decrease network transmission cost, frequently used data is cached from meta database. Existing cache management method has a unbalanced resource problem, because it doesn't manage replicated data in each node. Also, it increases network cost by cache misses. In the case of data modification, if cache is not updated, queries can be transferred to wrong nodes and it can be occurred others nodes which have same cache. Therefore, it is necessary to solve the problems of existing method that are using unbalanced resource of replica and increasing network cost by cache misses. In this paper, cache management method for query forwarding optimization is proposed. The proposed method manages caches through cache manager. To optimize query forwarding, the cache manager makes caching data from lower loaded replicated node.

응급실 내원 환자의 만족도 평가 및 관련 요인에 대한 연구

서강석,감신,박정배,이정헌,김종근,윤영국,곽경숙,이원기,우석정 大韓應急醫學會 1998 대한응급의학회지 Vol.9 No.4

Background: To examine the influencing factors on patients' satisfaction in the emergency department(ED) for quality assurance. Methods: Patients who visited to the ED were prospectively investigated from November 1 to December 31, 1997. Authors developed questionnaire to investigate influencing factors on patients' satisfaction. A Chi-square test and LISREL 7.0 were applied for statistical analysis. Results: Patients' satisfaction was significantly related to physical environment variables, accessibility variables, kindness of hospital personnel variables, and patient's trust for doctors variables. In path analysis, willingness for revisit was influenced by patients' satisfation, accessibility, physical environment, patients' trust for doctors in order, and willingness for recommendation was influenced by accessibility, patients' satisfaction, and kindness of hospital personnel in order. Conclusions: The influencing factors on patients' satisfaction are physical environment, accessibility, kindness of hospital personnel, and patient's trust for doctors. Willingness for revisit and willingness for recommendation are influenced by patients' satisfation. In spite of some limitations, the results of this study can be used as a baseline information for exploring the influencing factors on patients' satisfaction. Further comprehensive research efforts should be made on the study of patients' satisfactoin in the ED.