• Title/Summary/Keyword: Large tables

검색결과 141건 처리시간 0.027초

Monte Carlo Resonance Treatment for the Deterministic Transport Lattice Codes

  • Kim Kang-Seog;Lee Chung Chan;Chang Moon Hee;Zee Sung Quun
    • Nuclear Engineering and Technology
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    • 제35권6호
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    • pp.581-595
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    • 2003
  • Transport lattice codes require the resonance integral tables for the resonant nuclides where the resonance integral is a function of the background cross section and can be prepared through a special program solving the slowing down equation. In case the cross section libraries do not include the resonance integral table for the resonant nuclides, the computational prediction produces a large error. We devised a new method using a Monte Carlo calculation for the effective resonance cross sections to solve this problem provisionally. We extended this method to obtain the resonance integral table for general purpose. The MCNP code is used for the effective resonance integrals and the LIBERTE code for the effective background cross sections. We modified the HELIOS library with the effective cross sections and the resonance integral tables obtained by the newly developed Monte Carlo method, and performed sample calculations using HELIOS and LIBERTE. The results showed that this method is very effective for the resonance treatment.

Jackknifed Cochran-Mantel-Haenszel Test for Conditional Independence in Sparse $2\tims2\tims$K Tables

  • Jeong, Kwang-Mo
    • Communications for Statistical Applications and Methods
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    • 제8권1호
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    • pp.51-63
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    • 2001
  • We are interested in the conditional independence in sparse $2\tims2\tims$K tables with very rare cell counts. The most popular test is Cochran-Mantel-Haenszel statistic when sample sizes are moderately large enough to guarantee the chi-square approximation. We will consider jackknifing the CMH test and also suggest an approximate normal distribution for the standardized jackknifed CMH statistic. The main focus of this paper is to improve the chi-squared approximation to the CMH test by using the asymptotic normality of the jackknifed CMH test when sample sizes are very sparse but K and N$\infty$. The performance of the proposed jackknifed test, in the sense of significance level control and power, will be compared with that of the CMH test through a Monte Carlo study.

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가례도감의궤(嘉禮都監儀軌)에 나타난 (동뢰연(同牢宴))소용(所用) 기용고(器用考) -1744년(年) 장조(莊租) 헌경후(獻敬后) 1819년(年) 문조(文租) 신정후(神貞后) 가례동뢰연(嘉禮同牢宴)- (A Study on Wedding Ceremony Tablewares in Gare Dogam Euigwae(1744, 1819))

  • 김상보;이성우
    • 한국식생활문화학회지
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    • 제6권1호
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    • pp.21-29
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    • 1991
  • To analyze tableware in wedding ceremonies of royal prince(1744, 1819) of Chosun Dynasty, the author studied the historic book-Gare Dogam Euigwae, in which wedding feast dishes for King and prince in Chosun Dynasty were described. The results obtained from the study were as follows, 1. For wedding feast dishes for prince, black lacquered table was used, and for King's wedding feast red lacquered table was used. 2. In wedding ceremony red silk table cloth was used. 3. Tables arranged in wedding ceremony had high legs. 4. Tablewares used in wedding ceremony were footed dishes. 5. Wedding ceremony arrangement was made up of four kinds of main table, a small boiled beef table, a large boiled beef table, four small round tables, a dining table, a candle stick, a incense holder, a vase with vaseholder and a liquor bottle with a holder.

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Comparison Architecture for Large Number of Genomic Sequences

  • Choi, Hae-won;Ryoo, Myung-Chun;Park, Joon-Ho
    • 정보화연구
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    • 제9권1호
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    • pp.11-19
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    • 2012
  • Generally, a suffix tree is an efficient data structure since it reveals the detailed internal structures of given sequences within linear time. However, it is difficult to implement a suffix tree for a large number of sequences because of memory size constraints. Therefore, in order to compare multi-mega base genomic sequence sets using suffix trees, there is a need to re-construct the suffix tree algorithms. We introduce a new method for constructing a suffix tree on secondary storage of a large number of sequences. Our algorithm divides three files, in a designated sequence, into parts, storing references to the locations of edges in hash tables. To execute experiments, we used 1,300,000 sequences around 300Mbyte in EST to generate a suffix tree on disk.

관계형 데이터 웨어하우스의 복잡한 질의의 처리 효율 향상을 위한 비트맵 조인 인덱스 선택에 관한 연구 (A Study on Selecting Bitmap Join Index to Speed up Complex Queries in Relational Data Warehouses)

  • 안형근;고재진
    • 정보처리학회논문지D
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    • 제19D권1호
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    • pp.1-14
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    • 2012
  • 데이터 웨어하우스는 크기가 방대하기 때문에 인덱스의 선택은 질의어 처리의 효율성에 상대한 영향을 준다. 인덱스는 질의 처리 비용을 줄이지만, 그것이 차지하는 기억 영역과 데이터베이스의 변경에 따른 보수라는 비용이 수반된다. 데이터 웨어하우스에서 하나의 사실 테이블과 여러 개의 차원 테이블 사이의 조인을 행하는 스타 조인 질의어와 차원 테이블의 선택을 최적화하기 위해서 비트맵 조인 인덱스가 잘 적용된다. 비트맵 조인 인덱스는 이진수로 표현되기 때문에 저장 비용은 적게 들지만 인덱스 할 후보 속성들이 많이 생성되기 때문에 그 중에서 인덱스 할 속성들을 선택하는 일은 어려운 과제가 된다. 인덱스 선택은 일단 후보 속성들의 개수를 축소하고, 그 중에서 인덱스를 선택하게 된다. 본 논문에서는 데이터 마이닝 방법을 사용해서 비트 맵 조인 인덱스 선택 문제에서 후보 속성들의 개수를 축소하는 것을 해결한다. 질의어에 있는 속성들의 빈도에 기준해서 후보 속성들의 개수를 감소시키는 기존의 방법에 비해서 본 논문은 속성들의 빈도를 사용함과 동시에 차원 테이블의 크기, 차원 테이블의 튜플 크기, 디스크의 페이지 크기 등을 고려한다. 그리고 데이터마이닝 기법으로 빈발 항목집합을 마이닝하여 후보 속성들의 개수를 효과적으로 줄인다. 후보 속성집합들의 비트 맵 조인 인덱스에 비용함수를 적용해서 최소의 비용과 기억 영역 제한에 적합한 속성집합들의 비트 맵 조인 인덱스를 구한다. 본 논문의 방법의 효율성을 평가하기 위해서 기존의 방법들과 비교 분석을 한다.

대규모 미시교통시뮬레이션모형 구축을 위한 O/D 추정 방법 성능 비교 - 중력모형과 QUEENSOD 방법을 중심으로 - (Comparison Study of O/D Estimation Methods for Building a Large-Sized Microscopic Traffic Simulation Network: Cases of Gravity Model and QUEEENSOD Method)

  • 윤정은;이철기;이환필;김경현;박원일;윤일수
    • 한국도로학회논문집
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    • 제18권2호
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    • pp.91-101
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    • 2016
  • PURPOSES : The aim of this study was to compare the performance of the QUEENSOD method and the gravity model in estimating Origin-Destination (O/D) tables for a large-sized microscopic traffic simulation network. METHODS : In this study, an expressway network was simulated using the microscopic traffic simulation model, VISSIM. The gravity model and QUEENSOD method were used to estimate the O/D pairs between internal and between external zones. RESULTS: After obtaining estimations of the O/D table by using both the gravity model and the QUEENSOD method, the value of the root mean square error (RMSE) for O/D pairs between internal zones were compared. For the gravity model and the QUEENSOD method, the RMSE obtained were 386.0 and 241.2, respectively. The O/D tables estimated using both methods were then entered into the VISSIM networks and calibrated with measured travel time. The resulting estimated travel times were then compared. For the gravity model and the QUEENSOD method, the estimated travel times showed 1.16% and 0.45% deviation from the surveyed travel time, respectively. CONCLUSIONS : In building a large-sized microscopic traffic simulation network, an O/D matrix is essential in order to produce reliable analysis results. When link counts from diverse ITS facilities are available, the QUEENSOD method outperforms the gravity model.

맵리듀스 잡을 사용한 해시 ID 매핑 테이블 기반 대량 RDF 데이터 변환 방법 (Conversion of Large RDF Data using Hash-based ID Mapping Tables with MapReduce Jobs)

  • 김인아;이규철
    • 한국정보통신학회:학술대회논문집
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    • 한국정보통신학회 2021년도 추계학술대회
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    • pp.236-239
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    • 2021
  • AI 기술의 성장과 함께 지식 그래프의 크기는 지속적으로 확장되고 있다. 지식 그래프는 주로 트리플이 연결된 RDF로 표현되며, 많은 RDF 저장소들이 RDF 데이터를 압축된 형태의 ID로 변환한다. 그러나 RDF 데이터의 크기가 특정 기준 이상으로 클 경우, 테이블 탐색으로 인한 높은 처리 시간과 메모리 오버헤드가 발생한다. 본 논문에서는 해시 ID 매핑 테이블 기반 RDF 변환을 분산 병렬 프레임워크인 맵리듀스에서 처리하는 방법을 제안한다. 제안한 방법은 RDF 데이터를 정수 기반 ID로 압축 변환하면서, 처리 시간을 단축하고 메모리 오버헤드를 개선한다. 본 논문의 실험 결과, 약 23GB의 LUBM 데이터에 제시한 방법을 적용했을 때, 크기는 약 3.8배 가량 줄어들었으며 약 106초의 변환 시간이 소모되었다.

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IT 아웃소싱의 가치에 관한 연구: 한국 산업에 대한 실증분석 (Value of Information Technology Outsourcing: An Empirical Analysis of Korean Industries)

  • 한건수;이강배
    • Asia pacific journal of information systems
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    • 제20권3호
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    • pp.115-137
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    • 2010
  • Information technology (IT) outsourcing, the use of a third-party vendor to provide IT services, started in the late 1980s and early 1990s in Korea, and has increased rapidly since 2000. Recently, firms have increased their efforts to capture greater value from IT outsourcing. To date, there have been a large number of studies on IT outsourcing. Most prior studies on IT outsourcing have focused on outsourcing practices and decisions, and little attention has been paid to objectively measuring the value of IT outsourcing. In addition, studies that examined the performance of IT outsourcing have mainly relied on anecdotal evidence or practitioners' perceptions. Our study examines the contribution of IT outsourcing to economic growth in Korean industries over the 1990 to 2007 period, using a production function framework and a panel data set for 54 industries constructed from input-output tables, fixed-capital formation tables, and employment tables. Based on the framework and estimation procedures that Han, Kauffman and Nault (2010) used to examine the economic impact of IT outsourcing in U.S. industries, we evaluate the impact of IT outsourcing on output and productivity in Korean industries. Because IT outsourcing started to grow at a significantly more rapid pace in 2000, we compare the impact of IT outsourcing in pre- and post-2000 periods. Our industry-level panel data cover a large proportion of Korean economy-54 out of 58 Korean industries. This allows us greater opportunity to assess the impacts of IT outsourcing on objective performance measures, such as output and productivity. Using IT outsourcing and IT capital as our primary independent variables, we employ an extended Cobb-Douglas production function in which both variables are treated as factor inputs. We also derive and estimate a labor productivity equation to assess the impact of our IT variables on labor productivity. We use data from seven years (1990, 1993, 2000, 2003, 2005, 2006, and 2007) for which both input-output tables and fixed-capital formation tables are available. Combining the input-output tables and fixed-capital formation tables resulted in 54 industries. IT outsourcing is measured as the value of computer-related services purchased by each industry in a given year. All the variables have been converted to 2000 Korean Won using GDP deflators. To calculate labor hours, we use the average work hours for each sector provided by the OECD. To effectively control for heteroskedasticity and autocorrelation present in our dataset, we use the feasible generalized least squares (FGLS) procedures. Because the AR1 process may be industry-specific (i.e., panel-specific), we consider both common AR1 and panel-specific AR1 (PSAR1) processes in our estimations. We also include year dummies to control for year-specific effects common across industries, and sector dummies (as defined in the GDP deflator) to control for time-invariant sector-specific effects. Based on the full sample of 378 observations, we find that a 1% increase in IT outsourcing is associated with a 0.012~0.014% increase in gross output and a 1% increase in IT capital is associated with a 0.024~0.027% increase in gross output. To compare the contribution of IT outsourcing relative to that of IT capital, we examined gross marginal product (GMP). The average GMP of IT outsourcing was 6.423, which is substantially greater than that of IT capital at 2.093. This indicates that on average if an industry invests KRW 1 millon, it can increase its output by KRW 6.4 million. In terms of the contribution to labor productivity, we find that a 1% increase in IT outsourcing is associated with a 0.009~0.01% increase in labor productivity while a 1% increase in IT capital is associated with a 0.024~0.025% increase in labor productivity. Overall, our results indicate that IT outsourcing has made positive and economically meaningful contributions to output and productivity in Korean industries over the 1990 to 2007 period. The average GMP of IT outsourcing we report about Korean industries is 1.44 times greater than that in U.S. industries reported in Han et al. (2010). Further, we find that the contribution of IT outsourcing has been significantly greater in the 2000~2007 period during which the growth of IT outsourcing accelerated. Our study provides implication for policymakers and managers. First, our results suggest that Korean industries can capture further benefits by increasing investments in IT outsourcing. Second, our analyses and results provide a basis for managers to assess the impact of investments in IT outsourcing and IT capital in an objective and quantitative manner. Building on our study, future research should examine the impact of IT outsourcing at a more detailed industry level and the firm level.

NAND 플래시 기반 모바일 저장장치를 위한 사상 테이블 캐싱 기법 (A Mapping Table Caching Scheme for NAND Flash-based Mobile Storage Devices)

  • 양수현;류연승
    • 한국전자거래학회지
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    • 제15권4호
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    • pp.21-31
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    • 2010
  • 최근 모바일 컴퓨터를 사용한 온라인 금융 거래, 온라인 쇼핑과 같은 e-비즈니스가 널리 확산되고 있다. 대부분의 모바일 컴퓨터는 데이터 저장을 위해 NAND 플래시 메모리 기반의 저장장치를 사용한다. 플래시 메모리 저장장치는 그 내부에 Flash Translation Layer(FTL)이라는 소프트웨어가 사용되고 있다. FTL은 파일 시스템으로부터 요청되는 논리 주소를 플래시 메모리의 물리 주소로 변환하며 이를 위하여 사상 테이블을 사용한다. 기존 FTL은 매우 큰 주소 사상 테이블을 RAM에 유지해야 하는 문제점을 가지고 있다. 이를 해결하기 위하여 본 논문에서는 새로운 사상 테이블의 캐싱 기법을 제안하였다. 트레이스 기반의 시뮬레이션을 통해 제안한 사상 테이블 캐싱 기법은 공간 비용을 대폭 줄이고 시간 비용은 크게 증가하지 않음을 알 수 있었다. 특히, e-비즈니스 환경의 온라인 트랜잭션 워크로드에서 많은 공간 비용 절감 효과를 보였다.

A Data Mining Approach for Selecting Bitmap Join Indices

  • Bellatreche, Ladjel;Missaoui, Rokia;Necir, Hamid;Drias, Habiba
    • Journal of Computing Science and Engineering
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    • 제1권2호
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    • pp.177-194
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    • 2007
  • Index selection is one of the most important decisions to take in the physical design of relational data warehouses. Indices reduce significantly the cost of processing complex OLAP queries, but require storage cost and induce maintenance overhead. Two main types of indices are available: mono-attribute indices (e.g., B-tree, bitmap, hash, etc.) and multi-attribute indices (join indices, bitmap join indices). To optimize star join queries characterized by joins between a large fact table and multiple dimension tables and selections on dimension tables, bitmap join indices are well adapted. They require less storage cost due to their binary representation. However, selecting these indices is a difficult task due to the exponential number of candidate attributes to be indexed. Most of approaches for index selection follow two main steps: (1) pruning the search space (i.e., reducing the number of candidate attributes) and (2) selecting indices using the pruned search space. In this paper, we first propose a data mining driven approach to prune the search space of bitmap join index selection problem. As opposed to an existing our technique that only uses frequency of attributes in queries as a pruning metric, our technique uses not only frequencies, but also other parameters such as the size of dimension tables involved in the indexing process, size of each dimension tuple, and page size on disk. We then define a greedy algorithm to select bitmap join indices that minimize processing cost and verify storage constraint. Finally, in order to evaluate the efficiency of our approach, we compare it with some existing techniques.