• Journal of Internet Computing and Services
• /
• v.5 no.1
• /
• pp.67-84
• /
• 2004

Real-time database systems (RTDBS) are database systems whose transactions are associated with timing constraints such as deadlines. Therefore transaction needs to be completed by a certain deadline. Besides meeting timing constraints, a RTDBS needs to observe data consistency constraints as well. That is to say, unlike a conventional database system, whose main objective is to provide fast average response time, RTDBS may be evaluated based on how often transactions miss their deadline, the average lateness or tardiness of late transactions, the cost incurred in transactions missing their deadlines. Therefore, in RTDBS, transactions should be scheduled according to their criticalness and tightness of their deadlines, even If this means sacrificing fairness and system throughput, And It always must guarantee preceding process of the transaction with the higher priority. In this paper, we propose an efficient real-time scheduling algorithm (Multi-level EFDF) that alleviates problems of the existing real-time scheduling algorithms, a real-time concurrency control algorithm(2PL-FT) for firm and soft real-time transactions. And we compare the proposed 2PL F[ with AVCC in terms of the restarting ratio and the deadline missing ratio of transactions. We show through experiments that our algorithms achieve good performance over the other existing methods proposed earlier.

• Journal of Computing Science and Engineering
• /
• v.2 no.1
• /
• pp.44-73
• /
• 2008

There is general agreement that the problem of data semantics has to be addressed for XML data to become machine-processable. This problem can be tackled by defining a semantic mapping between an XML schema and an ontology. Unfortunately, creating such mappings is a tedious, time-consuming, and error-prone task. To alleviate this problem, we present a solution that heuristically discovers semantic mappings between XML schemas and ontologies. The solution takes as input an initial set of simple correspondences between element attributes in an XML schema and class attributes in an ontology, and then generates a set of mapping formulas. Once such a mapping is created, it is important and necessary to maintain the consistency of the mapping when the associated XML schema and ontology evolve. In this paper, we first offer a mapping formalism to represent semantic mappings. Second, we present our heuristic mapping discovery algorithm. Third, we show through an empirical study that considerable effort can be saved when discovering complex mappings by using our prototype tool. Finally, we propose a mapping maintenance plan dealing with schema evolution. Our study provides a set of effective solutions for building sustainable semantic integration systems for XML data.

• The Transactions of the Korea Information Processing Society
• /
• v.4 no.4
• /
• pp.1076-1088
• /
• 1997

Data repliciation techniques of distributed database a allocation methods occures to overhead to change together all repkicas for consistency maintenance at updates .In case of data migration horizontal or vertical fragment migration has caused to caused to increase data communication.In this paper we purpose batch proxessing method groups the associated items of table and stores temporary table assciated with file relication and migrations.This method increase the usagility of system buffer in distributed trancsaction processing with a number of data inputs and updates.After all,it improved the perform-ance of distributed transaction system by reducing disk I\O processing time and the cost of data cimmunication among local sites.

• Aerospace Engineering and Technology
• /
• v.13 no.1
• /
• pp.142-152
• /
• 2014

This paper analyzes the conjunction events of Korea satellites by year or kind of satellite using CSM, which is provided by JSpOC. If multiple CSM for single conjunction event are available, consistency analysis is performed using minimum range of CSM. And this paper presents the contact analysis results with space objects if there is a radar system in Korea. The effectiveness of Korea's radar system is analyzed by calculating the access time or frequency with space objects. Furthermore, we investigate the radar systems of other space agencies and find the specific parameter depending on the operating environment. Using this information, we define the requirements of radar system, which is appropriate the Korea.

• Wind and Structures
• /
• v.18 no.2
• /
• pp.195-213
• /
• 2014

Recently, the horizontal axis rotor performance optimizer (HARP_Opt) tool was developed in the National Renewable Energy Laboratory, USA. This innovative tool is becoming more popular in the wind turbine industry and in the field of academic research. HARP_Optwas developed on the basis of two fundamental modules, namely, WT_Perf, a performance evaluator computer code using the blade element momentum theory; and a genetic algorithm module, which is used as an optimizer. A pattern search algorithm was more recently incorporated to enhance the optimization capability, especially the calculation time and consistency of the solutions. The blade optimization is an aspect that is highly dependent on experience and requires significant consideration on rotor control strategies, wind data, and generator type. In this study, the effects of rotor control strategies including fixed speed and fixed pitch, variable speed and fixed pitch, fixed speed and variable pitch, and variable speed and variable pitch algorithms on optimal blade shapes and rotor performance are investigated using optimized blade designs. The effects of environmental wind data and the objective functions used for optimization are also quantitatively evaluated using the HARP_Opt tool. Performance indices such as annual energy production, thrust, torque, and roof-flap moment forces are compared.

• Asian-Australasian Journal of Animal Sciences
• /
• v.5 no.3
• /
• pp.439-447
• /
• 1992

Eight healthy Holstein bulls, 4-6 years old were used to study the effect of season of the year on the biophysical characteristics of semen. Semen was collected twice a week by AV (artificial vagina) over one-year period. The analyses revealed that all the basic seminal traits studied were differed significantly due to season, except the ejaculate volume and consistency and the percentage of swollen spermatozoa in a hypo-osmotic fructose-citrate solution. Ejaculates collected during hot summer season had significantly lower sperm motility, concentration and total counts, and higher percentage of dead spermatozoa than those collected during winter time. Warm spring had moderate semen quality. The temperature-humidity index was calculated and it was associated (p < 0.01) negatively with the ejaculate pH, sperm concentration and total counts, and positively with the % of dead sperms. Ejaculate volume, percentage of swollen spermatozoa, individual motilities did not correlate significantly with the change in temperature-humidity index values. The total live, motile spermatozoa per ejaculate during both the winter and spring seasons showed significant increase of about 37% and 32% respectively over the summer season. Also, rectal temperatures of the bulls were elevated during the hot summer season, while the values of blood hemoglobin and packed-cell volume were decreased.

• Journal of Korean Academy of Nursing
• /
• v.35 no.2
• /
• pp.362-371
• /
• 2005

Purpose: The aim of this study was to design and evaluate a scale for measuring reliability and validity in the field of oriental nursing education. Method: A questionnaire was administered to 495 university nursing students using a convenience sampling method. The period of time for collecting data was from September 2003 to January 2004. Result: The derived outcome tool consisted of 6 factors and 22 inquires on the basis of a conceptual frame of three domains (knowledge, attitude, and skill), As a result of the item analysis, 22 items were selected and the internal consistency alpha coefficient was .767. The value of Cronbach' Alpha of knowledge(factor 1) was .885, attitude(factor2)was .756, and skill (factor 3) was .610. The three factors accounted for $65.110\%$ of the variance in the total scale. Addressing the explanatory variance of each domain Cognitive domain was $22.477\%$, affective domain was $20.543\%$, and psychomotor domain was $17.090\%$. Conclusion: Further studies need to be done to verify educational evaluation and apply our outcomes to oriental nursing education.

• Journal of Korea Soil Environment Society
• /
• v.5 no.3
• /
• pp.17-23
• /
• 2001

The adsorption and movement characteristics of herbicide pendimethalin was studied in three kinds of soil, sandy loam, silty clay and loam. The results of the batch test and columnexperimentweresummarizedasfollows. The shaking time reached to the adsorption equilibrium of pendimethalin in soils was 6 hours. The adsorption rates of pendimethalin for sandy loam, silty clay and loam were 59.6%, 77.3% and 64.0%, respectively. The adsorption isotherms with the Freundlich equation showed better consistency than that with the Langmuir one. The adsorption coefficients of pendimethalin for soils were 8.0. 16.1 and 9.5. respectively. When breakthrough point was 0.05Co, the breakthrough times reached for soils were 256 minutes, 810 minutes and 420 minutes. respectively.

• The Journal of the Korea institute of electronic communication sciences
• /
• v.7 no.4
• /
• pp.873-879
• /
• 2012

Recently the cloud computing paradigm has been widely accepting in various applications. Data management system of cloud computing requires ability to manage tremendous data and supporting scalability. The former can be achieved by weaken consistency and limitation of transactions, and the latter needs expand or shrink of components. In this paper, we propose a transaction processing model and a scalable module management algorithm when transaction is executed in the cloud. Transaction processing model consists of a transaction management module and a data management module. Scalable module management algorithm has no redistribution of components and may alleviates loads of existed modules. With simulation results, we can see the improvement of response time and decrease abort ratio of transactions.

• Journal of the Korea Institute of Building Construction
• /
• v.8 no.1
• /
• pp.97-102
• /
• 2008

The report of the Korean Board of Audit and Inspection(BAI) on May 2007 indicates the problems of Life Cycle Cost (LCC) analysis and evaluation in the Design-Build(Turn-Key) and alternative bidding system. The point which the report indicates is that the cost estimation system for LCC analysis has nothing in common each other and there's no consistency among the repair cycle and ratio per facilities parts. For solving these problems, BAI demands the establishment of the guidelines for LCC analysis and evaluation from the competent authority Korean Ministry of Construction And Transportation(MOCT). The objective of this study is to develop the improvement directions for LCC analysis and evaluation which are suitable to the public construction projects especially for the Design-Build and alternative bidding system in Korea. For this study, the LCC related raws and regulations, LCC analysis guidelines of public cooperations, actual condition of LCC analysis and evaluation which include, the elements of LCC, the estimation rules of the initial cost and the maintenance cost, the analysis standards of time value of money, etc. are investigated to provide the improvement directions for LCC analysis and evaluation.