• The Journal of Korean Association of Computer Education
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• v.12 no.4
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• pp.65-75
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• 2009

The result verification is necessary to support a guarantee for the correctness of the task results be executed by any unspecified resources in desktop grid environments. Typically, voting-based and trust-based result verification schemes have been used in the environments. However, these suffer from two potential problems: waste of resources due to redundant replicas of each task and increase in turnaround time due to the inability to deal with a dynamic changeable execution environment. To overcome these problems, we propose a fuzzy inference-based replication scheme which can adaptively determine the number of replicas per task by using both trusty degree and result return probability of resources. Therefore our proposal can reduce waste of resources by determining the number of replicas meeting with a dynamic execution environment of desktop grids, not to mention an enhancement of turnaround time for entire asks. Simulation results show that our scheme is superior to other ones in terms of turnaround time, the waste of resources, and the number of re-replications per task.

• The Journal of the Korea Contents Association
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• v.16 no.8
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• pp.706-716
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• 2016

Because of efficient space utilization and fast key search times, B-trees have been widely accepted for the use of indexes in HDD-based DBMSs. However, when the B-ree is stored in flash memory, its costly operations of node updates may impair the performance of a DBMS. This is because the random updates in B-tree's leaf nodes could tremendously enlarge I/O costs for the garbage collecting actions of flash storage. To solve the problem, we make all the parents of leaf nodes the virtual nodes, which are not stored physically. Rather than, those nodes are dynamically generated and buffered by referring to their child nodes, at their access times during key searching. By performing node updates and tree reconstruction within a single flash block, our proposed B-tree can reduce the I/O costs for garbage collection and update operations in flash. Moreover, our scheme provides the better performance of key searches, compared with earlier flash-based B-trees. Through a mathematical performance model, we verify the performance advantages of the proposed flash B-tree.

• The Journal of the Korea Contents Association
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• v.9 no.12
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• pp.718-729
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• 2009

This study investigated the relationships between stress-coping strategies and the mental health of college students from health related and non-health related departments by developing an efficient managerial indicator using student lifestyle guidance and employment guidance. Results indicated that there are differences in stress factors between general characteristics and departments. Hope management was used the most for stress-coping strategies for health related departmental students and emotional management was used the most for stress-coping strategies for non-health related departmental students. Compulsion scored high for health related departmental students in regards to mental health while fear and hostility scored high for non-health related departmental students. Results also showed that active stress-coping strategies and paranoia were negatively correlated, while passive stress-coping strategies and many mental health substructure were positively correlated. In conclusion, negative influences on mental health is the reason for instances where stress-coping strategies were not pertinent. Therefore colleges and professors should consider developing a program which can appropriately manage and regulate college students stress and thereby allow students to actively participate with benefits from college lifestyle guidance and employment guidance.

• Journal of Korea Port Economic Association
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• v.24 no.4
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• pp.385-406
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• 2008

This study aims to contribute regional economic development by means of searching port logistics industry activation scheme of Gangwon province which has locational advantage around the East Sea Region. Thus, this thesis was provided the port logistics industry activation schemes of that region in the point of local and government view. In the local government level, this study was provided the selection of a key port and its intensive development, establishment of port networking among major port and e-port system of this region, and enlargement of the FTA etc. Also this study was required the relative industry invitation and upbringing, and intensive port logistics marketing activity. On the other hand, in the government level, it needs larger SOC investment for enlargement of direct accessibility and connection to the Gangwon-do ports, and required the intensive and efficient support. Finally, it was proposed the establishment of the total logistics expert education system.

• Proceedings of the Korea Water Resources Association Conference
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• 2009.05a
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• pp.347-353
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• 2009

수문조사기기의 검정은 수문조사에 활용하거나 활용하고자 할 다양한 수문조사기기를 일관되고 표준화된 기준으로 검사하여 수문조사에 적합한 기기를 설치하거나 지속적으로 사용하도록 하고자 하는 것이다. 이러한 검정은 국가수문자료의 신뢰도를 높이고 유지하고자 하는 기본적이고 중요한 업무이다. 국내에서는 2009년 2월 현재 회전식 유속측정기기와 일부 강수량측정기기만을 검정하고 수문조사에 활용하고 있는 실정이다. 따라서 수문자료의 신뢰도에 대해 제시할 수 있는 지표는 유량측정결과의 불확도와 일부 강수량계를 제외하고 사실상 없다고 할 수 있다. 그 밖의 수문조사기기들에 의해 생산된 수문자료는 단지 제조사에서 제공하고 있는 정확도와 정밀도 등의 정보를 통해서 가늠하고 있어 국가수문자료로서의 신뢰성으로 제시하기에는 부족하다고 할 수 있다. 수문조사기기의 검정시행을 위해서는 각 기기에 대하여 검정방법, 허용오차, 검정기관의 조건 및 기타 행정적 체계 등이 필요하다. 본 연구에서는 국내에서 사용되고 있는 수문조사기기의 현황을 파악하고 대상기기를 선별할 수 있도록 하였다. 그리고 각 대상 수문조사기기에 대한 검사방법과 허용오차를 규정하기 위해 공통적으로 필요한 과정과 방법론을 제시하여 객관적으로 신뢰할 수 있으며 효율적으로 적용 가능한 검사방법과 허용오차를 결정할 수 있도록 하였다. 또한 공신력 있는 검정 결과를 보장하기 위해 검정기관에서 갖추어야 할 인력, 설비 및 품질 시스템 등이 국제표준(ISO)에 부합되면서도 수문조사분야에 효율적으로 적용될 수 있는 조건들에 대해 분석 제안하였다. 본 연구결과는 국가차원에서 신뢰할 수 있는 공인검정기관이 수문조사기기 검정을 시행할 수 있게 하는 초석이 될 것이며, 수문조사기기의 검정이 시행되면 이후 생산되는 수문자료는 정해진 검사방법과 허용오차 이내의 품질을 공인검정기관이 인정하는 수문자료로서의 신뢰도를 확보하게 될 것으로 기대된다.

• Proceedings of the Korea Water Resources Association Conference
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• 2009.05a
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• pp.529-534
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• 2009

Climate models, both global and regional, have increased in sophistication and are being run at increasingly higher resolutions. The Land Surface Models (LSMs) coupled to these climate models have evolved from simple bucket models to sophisticated Soil-Vegetation-Atmosphere Transfer (SVAT) schemes needed to support complex linkages and processes. However, some underpinnings of terrestrial hydrologic parameterizations so crucial in the predictions of surface water and energy fluxes cause model errors that often manifest as non-linear drifts in the dynamic response of land surface processes. This requires the improved parameterizations of key processes for the terrestrial hydrologic scheme to improve the model predictability in surface water and energy fluxes. The Common Land Model (CLM), one of state-of-the-art LSMs, is the land component of the Community Climate System Model (CCSM). However, CLM also has energy and water biases resulting from deficiencies in some parameterizations related to hydrological processes. This research presents the implementation of a selected set of parameterizations and their effects on the runoff prediction. The modifications consist of new parameterizations for soil hydraulic conductivity, water table depth, frozen soil, soil water availability, and topographically controlled baseflow. The results from a set of offline simulations are compared with observed data to assess the performance of the new model. It is expected that the advanced terrestrial hydrologic scheme coupled to the current CLM can improve model predictability for better prediction of runoff that has a large impact on the surface water and energy balance crucial to climate variability and change studies.

• Journal of Korea Water Resources Association
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• v.42 no.4
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• pp.271-279
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• 2009

The objective of this study is to develop the scheme to apply one-dimensional finite volume method (FVM) to natural river with complex geometry. In the previous study, FVM using the Riemann approximate solver was performed successfully in the various cases of dam-break, flood propagation, etc. with simple and rectangular cross-sections. We introduced the transform the natural into equivalent rectangular cross-sections. As a result of this way, the momentum equation was modified. The accuracy and applicability of newly developed scheme are demonstrated by means of a test example with exact solution, which uses triangular cross-sections. Secondly, this model is applied to natural river with irregular cross-sections and non-uniform lengths between cross-sections. The results shows that the aspect of flood propagation, location and height of hydraulic jump, and numerical solutions of maximum water level are in good agreement with the measured data. Using the developed scheme in this study, existing numerical schemes conducted in simple cross-sections can be directly applied to natural river without complicated numerical treatment.

• Journal of the Korean Professional Engineers Association
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• v.19 no.2
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• pp.10-20
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• 1986

This paper describes a countermeasure of electric utilities and customer equipment in order to minimize an effect of sensitive electrical and electronic equipment on the voltage disturbances. After being studied, some schemes to solve were discovered. Firstly, in the electric utilities, the reduction of frequency and influence of voltage drop's time are not easy to realize because of the standpoint of effect and economy. Secondly, in the customer equipment, there are some equipment to minimize the voltage disturbances, Such as an UPSs, a noise suppressors and a power conditioners. One of them should be established on the computer control and automated systems, the electromagnetic switch of delay-release type should be adopted on the electromagnetic switch, the controlling circuit should be adopted on the variable speed motors which is being considered a countermeasure for a momentary under-voltage drops, the luminaire adhering a instantaneous restrike device should be adopted on the HID lamp. And also, the scheme of extending a setting time of relay on the undervoltage relay and the forming method of sequence which is automatic reclosing at this time of instantaneous suspension of an electric supply have been studied.

• The Journal of the Korea Contents Association
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• v.11 no.4
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• pp.33-41
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• 2011

Although conventional text-based passwords are used as the most common authentication method, they have significant drawbacks such as guess attacks, dictionary attacks, key loggers, and shoulder-surfing. To address the vulnerabilities of traditional text-based passwords, graphical password schemes have been developed as possible alternative solutions, but they have a potential drawback that they are more vulnerable to shoulder-surfing than conventional text-based passwords. In this paper, we present a new Hangul password input method to prevent shoulder-surfing attacks. Our approach uses Hangul as a password, and it requires the users to locate their password in the given wheeling password grid instead of entering the password. Our approach makes it difficult for attackers to observe a user's password since the system shows the users' passwords with decoy characters as the noise on the screen. Also, we provide security analysis for random attacks, dictionary attacks, and shoulder-surfing attacks, and it shows that our password system is robust against these attacks.

• The Journal of the Korea Contents Association
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• v.17 no.3
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• pp.370-381
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• 2017

Recently, a complex event processing system has been introduced to quickly and efficiently process real-time events in various applications. Since the existing complex event processing schemes do not consider the similarity and duplication of operators, they perform a lot of computations and consume memory. To solve such problems, this paper proposes an efficient complex event processing scheme considering similar operators and duplication operations. When the same primitive events have similar operations, the proposed scheme combines them into one virtual operator. For duplicated operations, the proposed scheme processes only one of them first, and then processes the others using the results of the already processed operation when the same operation is subsequently performed. It is shown through performance comparison that the proposed scheme outperforms the existing scheme in terms of the whole operation throughput.