• The KIPS Transactions:PartC
• /
• v.16C no.6
• /
• pp.761-772
• /
• 2009

A DHT(Distributed Hash Table) based P2P is a method to overcome disadvantages of the existing unstructured P2P method. If a DHT algorithm is used, it can do a fast data search and maintain search efficiency independent of the number of peer. The peers in the DHT method send messages periodically to keep the routing table updated. In a mobile environment, the peers in the DHT method should send messages more frequently to keep the routing table updated and reduce the failure of a request. Therefore, this results in increase of network traffic. In our previous research, we proposed a method to reduce the update load of the routing table in the existing Chord by updating it in a reactive way, but the reactive method had a disadvantage to generate more traffic than the existing Chord if the number of requests per second becomes large. In this paper, we propose an adaptive method of routing table update to reduce the network traffic. In the proposed method, we apply different routing table update method according to the number of request message per second. If the number of request message per second is smaller than some threshold, we apply the reactive method. Otherwsie, we apply the existing Chord method. We perform experiments using Chord simulator (I3) made by UC Berkeley. The experimental results show the performance improvement of the proposed method compared to the existing methods.

• Journal of the Korean earth science society
• /
• v.37 no.2
• /
• pp.117-131
• /
• 2016

The purpose of this study was to compare of freshmen's cognitive frames about the 'Crisis of the Earth' upon taking the Earth science I course in high school to confirm if they reflect the goal of the curriculum reasonably. Data were collected from 67 freshmen who graduated from high school. All participants were asked to express about the 'Crisis of the Earth' in painting with explanation, then we picked meaningful units from paintings. We analyzed the words and frames presented in the paintings using the Semantic Network Analysis. Result are as follows. First, when both groups' (one that took the course vs. the other that did not take it) built their cognitive frames for the 'crisis of the Earth', they reasonably connected areas that are composed of the global environment and they understood that their relation was constantly changing by interacting each other. Second, when configuring a cognitive frame about the 'crisis of the Earth', both groups reflected the characteristics of interrelationship with human activities. In particular, the group that took the course of Earth Science I fully reflected the goal of the curriculum. It is suggested that students recognize the 'crisis of the Earth' not only from a cosmic perspective bot also from the Earth's interior since most of students have strongly connected it to the phenomenon of the Earth's interior rather than the Earth's outward symptoms. In addition, it is recommended that the Earth science curriculum put more emphasis on understanding the importance of problem-solving of the Earth's crisis.

• Journal of the Korea Concrete Institute
• /
• v.26 no.3
• /
• pp.239-245
• /
• 2014

This study analyzed a comprehensive database including 6331 ready-mixed concrete plant mixtures to quantitatively assess the environmental impact of concrete under mixture proportions variable according to the domestic region and season. The environmental impact indicator includes global warming, photochemical oxidant creation, abiotic resource depletion, acidification, eutrophication and human toxicity, which are determined from categorization, characterization, normalization and weighting process based on Korea lifecycle inventories. The determined environmental impact indicator was also normalized by concrete compressive strength ($f_{ck}$), which is defined as impact index, to calculate the environmental impact per unit strength of 1 MPa. The most common compressive strength of concrete used in the country is estimated to be 24 MPa and 27 MPa. For $f_{ct}$ of 24 MPa, the lowest environmental impact indicator is observed in Ulsan, whereas the highest region is Gwangju and Daegu. This difference according to domestic region is primarily resulted from by the replacement of different supplementary cementitious materials. Furthermore, the impact index of concrete with $f_{ck}$ of 24 MPa is higher by approximately 5% at wintertime than at summertime and standard season. The impact index gradually decreases with the increase of $f_{ck}$ up to 35 MPa, beyond which it remains constant.

• Journal of the Korean Data and Information Science Society
• /
• v.28 no.1
• /
• pp.143-152
• /
• 2017

Restriction of completely randomization within a block can be handled by a split plot factorial design splitted by several plots. $3{\times}3$ split plot factorial design with two fixed main factors and one fixed block shows that powers of the rank transformed statistic for testing whole plot factorial effect and split plot factorial effect are superior to those of the parametric statistic when existing effect size is small or the remaining effect size is relatively smaller than the testing factorial effect size. Powers of the rank transformed statistic show relatively high level for exponential and double exponential distributions, whereas powers of the parametric and rank transformed statistic maintain similar level for normal and uniform distributions. Powers of the parametric and rank transformed statistic with two fixed main factors and one random block are respectively lower than those with all fixed factors. Powers of the parametric andrank transformed statistic for testing split plot factorial effect with two fixed main factors and one random block are slightly lower than those for testing whole plot factorial effect, but powers of the rank transformed statistic show comparative advantage over those of the parametric statistic.

• Journal of Practical Engineering Education
• /
• v.12 no.1
• /
• pp.213-230
• /
• 2020

Until now, various educational budgets, facilities, and programs have been put into school education, but the results have not been clearly evaluated. This study presents a model to analyze the effectiveness of educational support for students in high schools across the country. In this model, we first use EM cluster analysis to make clusters with similar inputs for school operation, and then calculate the relative efficiency in each cluster by using Network DEA analysis. The Network DEA analysis has a two-stage structure where the first stage uses six inputs in terms of school infrastructure to generate outputs such as the number of academic persistence. In the Network DEA analysis, the second stage uses 10 inputs in terms of school programs to generate outputs such as the number of enrollees to higher learning and the number of employees and per capita usage of library as the connection variable. Based on the efficiency analysis results, Tier analysis is performed by applying the Euclidean distance to select targets for benchmarking. In this study, we applied the model to analyze the efficiency of educational support by collecting data regarding student education support in general and vocational high school nationwide. The stepwise benchmarking method proposed that the target be selected for efficiency improvement step by step, taking into account inefficient school elements to complement the problem of the choice of benchmarking targets. Based on this study, it is expected that schools with low efficiency of educational support for students will be used as basic data for stepwise benchmarking for efficient operation of educational support for students.

• The Transactions of the Korea Information Processing Society
• /
• v.4 no.2
• /
• pp.465-482
• /
• 1997

In this paper, we have studied on cinstructing code-recognition shstem by neural network according to a image process taking the DOT classification code stamped on tire surface.It happened to a few problems that characters distorted in edge by diffused reflection and two adjacent characters take the same label,even very sen- sitive to illumination ofr recognition the stamped them on tire.Thus,this paper would propose the algorithm for tire code under being cinscious of these properties and prove the algorithm drrciency with a simulation.Also,we have suggerted the MCBP network composing of multi-linked recognizers of dffcient identify the DOT code being tire classification code.The MCBP network extracts the projection balue for classifying each character's rdgion after taking out the prjection of each chracter's region on X,Y axis,processes each chracters by taking 7$\times$8 normalization.We have improved error rate 3% through the MCBP network and post-process comparing the DOT code Database. This approach has a accomplished that learming time get's improvenent at 60% and recognition rate has become to 95% from 90% than BckPropagation with including post- processing it has attained greate rates of entire of tire recoggnition at 98%.

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
• /
• v.12 no.4
• /
• pp.85-96
• /
• 2017

There are many people who start business because of unstable employment due to income polarization. There are many people who start business because of unstable this study is to present the necessary situation and direction for the prospective founders who are hesitant to start their own business by lacking self - confidence and information about Preparing for start-up the purpose of this study is to investigate the effect of pre - founder's psychological characteristics and start - up preparation characteristics on entrepreneurship intention. In order to conduct this study, 144 male and 114 female who were temporary workers and about to retire were analyzed for validity and reliability using 258 questionnaires. As a result of analyzing the adjustment effect of entrepreneurship education as an interaction term in the psychological characteristics and the preparation characteristics of the entrepreneurship, the risk taking tendency and the preparation period for entrepreneurship were significant for entrepreneurship education. In addition, the greater the necessity and importance of entrepreneurship education, the greater the effect on entrepreneurship education. It is a meaningful study that can give confidence to the subjects who want to start a business but are afraid of failure. This study is expected to contribute to the government's start - up policy by analyzing the influence of pre - founders on the intention of start - up.

• The KIPS Transactions:PartA
• /
• v.16A no.2
• /
• pp.113-124
• /
• 2009

With increasing multicore system, much effort has been put on the performance improvement of its application. Because multicore system has multiple processing devices in one system, its processing power increases compared to the single core system. However in many cases the advantages of multicore can not be exploited fully because the existing software and hardware were designed to be suitable for single core. When the existing software runs on multicore, its performance improvement is limited by the bottleneck of sharing resources and the inefficient use of cache memory on multicore. Therefore, according as the number of core increases, it doesn't show performance improvement and shows performance drop in the worst case. In this paper we propose a method of performance improvement of multicore system by applying Flow-Level Parallelism to the existing TCP/IP network application and operating system. The proposed method sets up the execution environment so that each core unit operates independently as much as possible in network application, TCP/IP stack on operating system, device driver, and network interface. Moreover it distributes network traffics to each core unit through L2 switch. The proposed method allows to minimize the sharing of application data, data structure, socket, device driver, and network interface between each core. Also it allows to minimize the competition among cores to take resources and increase the hit ratio of cache. We implemented the proposed methods with 8 core system and performed experiment. Experimental results show that network access speed and bandwidth increase linearly according to the number of core.

• The Korean Journal of Nuclear Medicine
• /
• v.39 no.3
• /
• pp.163-173
• /
• 2005

Purpose: Abutted scatter energy windows used for a triple energy window (TEW) method may provide wrong estimation of scatter. This study is to propose an extended TEW (ETEW) method, which doesn't require abutted scatter energy windows and overcomes the shortcomings of TEW method. Materials & Methods: The ETEW is a modification of the TEW which corrects for scatter by using abutted scatter rejection windows, which can overestimate or underestimate scatter. The ETEW is compared to the TEW using Monte Carlo simulated data for point sources as well as hot and cold spheres in a cylindrical water phantom. Various main energy window widths (10 %, 15 % and 20 %) were simulated. Both TEW and ETEW improved image contrast, % recovery coefficients and normalized standard deviation. Results: Both of TEW and ETEW improved image contrast and % recovery coefficients. Estimated scatter components by the TEW were not proportional to the true scatter components over the main energy windows when ones of 10 %, 15 %, and 20 % were simulated. The ETEW linearly estimated scatter components over the width of the main energy windows. Conclusion: We extended the TEW method into the method which could linearly estimate scatter components over the main energy windows.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.20 no.2
• /
• pp.458-468
• /
• 2019

This research attempted to estimate monthly sales of food and beverage at the passenger terminal of Incheon int'l airport from June of 2015 to December 2020. This paper used ARIMA-Intervention model which can estimate the change of the sales amount suggesting the predicted monthly food and beverage sales revenue. The intervention variable was travel-ban policy against south Korea from P.R. China since July 2016 to December 2017 due to THAAD in south Korea. According to ARIMA, it was found normal predicted sales amount showed the slow growth increase rate until 2020 due to the effect of intervened variable. However, the monthly food sales in July and August 2019 was 20.3 and 21.2 billion KRW respectively. Each amount would increase even more in 2020 and the amount would increase to 21.4 and 22.1 billion KRW. The sales amount in 2019 would be 7.7 and 8.1 billion KRW and climb up 7.9 and 8.2 billion KRW in 2020. It was expected LCC passengers tend to spend more money for F&B at airport due to no meal or drink service of LCC or the paid-in meal and beverage service of LCC. The growth of sales of food and beverate will be accompanied with the growth of LCC according to estimated data.