• Journal of Information Technology Services
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• 제5권3호
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• pp.121-135
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• 2006

With the growth and maturation of IT industry, the necessity of audit about development, maintenance and management of high-quality information system is gradually increasing. In addition, the necessity of inner auditing system, which could totally verify and evaluate the effectiveness of project according to the characteristics of organization conducting information-oriented business, also being proposed. Government offices including Korea Institute of Science and Technology(KISTI) collectively controlling nationwide science-technology related information have no guiding principle or organization within themselves even though performing information-oriented businesses are becoming more bigger and complicated. In this paper, we propose scheme for devising framework, which can audit construction and operation of knowledge information, check list and guideline. In addition, we present concrete ways for adapting these schemes to institutes which manage science-technology knowledge information. Audit framework consists of points of time in audit, audit domain and audit criterion. Points of time in audit are defined as three phases as followings: pre-audit, in-progress audit and post-audit. Audit domain includes 16 detail audit domains and especially we set 11 check items and 40 detail investigation items for database implementation business. We expect that management level of science-technology implementation business of organizations using this research result will increase and they could offer high-quality information service.

• Journal of Korean Society of Industrial and Systems Engineering
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• 제41권4호
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• pp.171-178
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• 2018

Recently, the continuing operation of nuclear power plants has become a major controversial issue in Korea. Whether to continue to operate nuclear power plants is a matter to be determined considering many factors including social and political factors as well as economic factors. But in this paper we concentrate only on the economic factors to make an optimum decision on operating nuclear power plants. Decisions should be based on forecasts of plant accident risks and large and small accident data from power plants. We outline the structure of a decision model that incorporate accident risks. We formulate to decide whether to shutdown permanently, shutdown temporarily for maintenance, or to operate one period of time and then periodically repeat the analysis and decision process with additional information about new costs and risks. The forecasting model to predict nuclear power plant accidents is incorporated for an improved decision making. First, we build a one-period decision model and extend this theory to a multi-period model. In this paper we utilize influence diagrams as well as decision trees for modeling. And bayesian statistical approach is utilized. Many of the parameter values in this model may be set fairly subjective by decision makers. Once the parameter values have been determined, the model will be able to present the optimal decision according to that value.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• 제59권2호
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• pp.145-154
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• 2023

In this study, to control the heading angle of a ship, which is constantly subjected to various internal and external disturbances during the voyage, an LADRC (linear active disturbance rejection control) design that focuses more on improving the disturbance removal performance was proposed. The speed rate of change of the ship's heading angle due to the turn of the rudder angle was selected as a significant factor, and the nonlinear model of the ship's maneuvering equation, including the steering gear, was treated as a total disturbance. It is the similar process with an LADRC design for the first-order transfer function model. At this time, the gains of the controller included in LADRC and the gains of the extended state observer were tuned to RCGAs (real-coded genetic algorithms) to minimize the integral time-weighted absolute error as an evaluation function. The simulation was performed by applying the proposed GA-LADRC controller to the heading angle control of the Mariner class vessel. In particular, it was confirmed that the proposed controller satisfactorily maintains and follows the set course even when the disturbances such as nonlinearity, modelling error, uncertainty and noise of the measurement sensor are considered.

• International conference on construction engineering and project management
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• The 6th International Conference on Construction Engineering and Project Management
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• pp.328-332
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• 2015

By logging position data from GPS-equipped construction machines, we re-create daily activities as 3D animations to analyze performance and facilitate look-ahead scheduling. The 3D animation enables going back to any point in time and space to observe the activities as they took place. By segmenting data into a set of activities, it is possible to obtain actual measures of performance such as cycle times, production, speed profiles and idle times. The measures of performance can then be compared to those expected (e.g., theoretical speed profiles vs. observed profiles), and instances of significant difference can be flagged for further investigation. Idle times and queues that exceed prescribed thresholds can also be identified. In general, many of the traditional real-time performance analyses can be performed after the fact. Situations of interest can be identified automatically and the events in this manner enhances effective performance improvement in construction. The proposed research is explained and demonstrated using a real push-loaded earthmoving operation.

• Journal of KIISE:Databases
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• 제35권6호
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• pp.459-468
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• 2008

A data stream which is a massive unbounded sequence of data elements continuously generated at a rapid rate. Many recent research activities for emerging applications often need to deal with the data stream. Such applications can be web click monitoring, sensor data processing, network traffic analysis. telephone records and multi-media data. For this. data processing over a data stream are not performed on the stored data but performed the newly updated data with pre-registered queries, and then return a result immediately or periodically. Recently, many studies are focused on dealing with a data stream more than a stored data set. Especially. there are many researches to optimize continuous queries in order to perform them efficiently. This paper proposes a query optimization algorithm to manage continuous query which has multiple join operators(Multi-way join) over data streams. It is called by an Extended Greedy query optimization based on a greedy algorithm. It defines a join cost by a required operation to compute a join and an operation to process a result and then stores all information for computing join cost and join cost in the statistics catalog. To overcome a weak point of greedy algorithm which has poor performance, the algorithm selects the set of operators with a small lay, instead of operator with the smallest cost. The set is influenced the accuracy and execution time of the algorithm and can be controlled adaptively by two user-defined values. Experiment results illustrate the performance of the EGA algorithm in various stream environments.

• Journal of Radiation Industry
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• 제18권1호
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• pp.43-52
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• 2024

Currently, there are no interim storage facilities and permanent disposal facilities in Korea, so all spent nuclear fuels are temporarily stored. However, the temporary storage facility is approaching saturation, and as a measure to this, the 2nd Basic Plan for the Management of High-Level Radioactive Waste presented an operation plan for dry interim storage facilities and dry temporary storage facilities on the NPP on-site. The dry storage can be operated in various ways, and to select the optimal dry storage method, the reduction of exposure for workers must be considered. Accordingly, it is necessary to develop a worker exposure scenario according to the dry storage method and evaluate and compare the radiological impact for each method. The purpose of this study is to develop an exposure scenario for workers transporting spent nuclear fuel by dry storage method. To this end, first, the operation procedure of the foreign commercial spent nuclear fuel dry storage system was analyzed based on the Final Safety Analysis Report (FSAR). 1) the concrete overpack-based system, 2) the metal overpack-based system, and 3) the vertical storage module-based system were selected for analysis. Factors were assumed that could affect the type of work (working distance, working hours, number of workers, etc.) during transportation work. Finally, the work type of the processes involved in transporting spent nuclear fuel by dry storage method was set, and an exposure scenario was developed accordingly. The concrete overpack method, the metal overpack method, and the vertical storage module method were classified into a total of 31, 9, and 23 processes, respectively. The work distance, work time, and number of workers for each process were set. The product of working hours and number of workers (Man-hour) was set high in the order of concrete overpack method, vertical storage module method, and metal overpack method, and short-range work (10 cm) was most often applied to the concrete overpack method. The results of this study are expected to be used as basic data for performing radiological comparisons of transport workers by dry storage method of spent nuclear fuel.

• The Journal of Korean Institute of Communications and Information Sciences
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• 제31권8A호
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• pp.830-836
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• 2006

One of the seminal operation parameters of AODV is the node-to-node travel time of data, which is currently set to fixed value of 40 ms in the RFC3561 and widely used to compute other parameters such as the expected round-trip time of the connection setup message, etc. We have naturally thought the network performance could be improved by dynamically varying the node-to-node travel time with respect to the traffic condition in the networt rather than using the fixed value, which motivates this work. To this end, we apply the idea of using timestamp; every node places the current time in the message before sending it out, and the receiver node computes the node travel time based on the moving average algorithm by considering not only the current value but also the previous ones in an accumulated and exponentially decreasing fashion with time. We evaluate the performance of the proposed scheme in respect of the number of RREQ messages generated, throughput, and delay as a function of traffic load and node mobility, and compare the result with the original AODV scheme. The results show that the proposed scheme presents noticeable performance improvements, expecially under the condition of high node mobility and high traffic load.

• IE interfaces
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• 제16권spc호
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• pp.99-104
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• 2003

While demands for express service are rapidly increasing according to recent progress of electronic commerce, express service companies are struggling to take a larger delivery service market share through ongoing improvement in their service processes. Extension of cut-off time for express service centers can provide the express company with increase of total sales, but it may also cause to increase the possibility not to satisfy customer needs due to work delay in the consolidation terminal. Therefore, compromised decision for cut-off time of each service center should be made by taking operation characteristics of the consolidation terminal into account. This study suggests an approach for determining the cut-off time for express service centers according to operational characteristics of the consolidation terminal with the objective of maximizing expected incremental sales. The problem defined in this study can be represented as two successive models; one is an integer programing model in which the best cut-off time for each sales center are determined, and the other is a single machine scheduling model in which a working schedule in the consolidation terminal is obtained. A genetic algorithm is developed to solve the two models simultaneously. Finally, an example problem is carried out to verify applicability and performance of the algorithm with the data set collected from an express company.

• Journal of KIISE:Databases
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• 제29권1호
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• pp.34-43
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• 2002

Since traditional static metadata set like Dublin Core has static metadata attributes about bibliography information, integration of metadata for various metadata, problems about standard and extension of metadata must be considered for applying it to new environment. Specially, as event-driven metadata write method included the notion of e-commerce come out for interoperability in digital libraries, traditional metadata management which cannot distinguish between different kinds of update operations to new extension of metadata set occurs unsuitable waiting of update operation. So, improvement is needed about it. In this paper, we show whether alleviative transaction consistency can be applied to digital library or not. Also it would divide newer metadata into static metadata attribute connected in read operation within user read-only transaction and dynamic metadata attribute in update operation within dynamic(e-commerce) update transactions. We propose newer metadata management algorithm considered in classfication of metadata attributes and dynamic update transaction. Using two version for minimal maintenance cost and ARU(Appended Refresh Unit) for dynamic update transaction, to minimize conflict between read and write operations shows fast response time and high recency ratio. As a result of the performance evaluation, we show our algorithm is proved to be better than other algorithms in newer metadata environments.

• Journal of the Korea Academia-Industrial cooperation Society
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• 제21권3호
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• pp.269-275
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• 2020

RAM of elements to support weapon systems is conducted at the initial development phase and standard is suggested to accomplish strategy requirement performance from a design spec. Operational availability is a key point of the military's ability to ensure combat readiness and to win the battle. In the weapon system development phase, operational availability is used as a development standard. The military provides ALDT, operation and standby time, which are elements of operational availability. ALDT is a key element of operational availability that must be maintained for combat readiness, as it depends on the aging of a weapon system, maintenance policies and geographical conditions. Operational Availability to be set at the development phase has many differences from the operational availability that is analyzed in the actual operational phase because ALDT is applied as a simple assumption. In the paper, we analyzed ALDT applying the decision tree method through failure data acquired from initial operation. Through this study, we have devised the optimal ALDT setting method to achieve operational availability about operation when the weapons system is unstable.