• Journal of Korean Society of Industrial and Systems Engineering
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• v.44 no.3
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• pp.22-32
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• 2021

To meet rapidly changing market demands, manufacturers strive to increase both of productivity and diversity at the same time. As a part of those effort, they are applying flexible manufacturing systems that produce multiple types and/or options of products at a single production line. This paper studies such flexible manufacturing system with multiple types of products, multiple Bernoulli reliability machines and dedicated buffers between them for each of product types. As one of the prevalent control policies, priority based policy is applied at each machines to select the product to be processed. To analyze such system and its performance measures exactly, Markov chain models are applied. Because it is too complex to define all relative transient and its probabilities for each state, an algorithm to update transient state probability are introduced. Based on the steady state probability, some performance measures such as production rate, WIP-based measures, blocking probability and starvation probability are derived. Some system properties are also addressed. There is a property of non-conservation of flow, which means the product ratio at the input flow is not conserved at the succeeding flows. In addition, it is also found that increased buffer capacity does not guarantee improved production rate in this system.

• The Journal of the Korea institute of electronic communication sciences
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• v.12 no.5
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• pp.737-746
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• 2017

In 2017, amid changes in the security market such as integrated security (IS) and convergence security (CS), a variety of security paradigms in terms of operation and management have been suggested. Rather than changing existing network infrastructure and bringing about fluid, multi-dimensional changes, these solutions and technologies focus entire security capacity on a primary protection, leading to network infrastructure suffering from unexpected inherent violations and problems in a continued manner. Therefore, it is time to propose and develop a flexible network section that can protect from attacks of similar pattern and concentrated traffic attacks by applying a new concept of WB (Water-Bubble) to network infrastructure and analyzing on the basis of experiment and installation. Methodology of the WB-based highly secure flexible network section proposed in this study is expected to provide materials for studies on how to achieve network section security taking into account three major limitations and security standards: fluidity, unpredictability, and non-area scalability by contact point ratio, by changing a network area predicted to be the final target of attack into resonant network section (area) with flexible area changes.

• Journal of The Korean Society of Agricultural Engineers
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• v.47 no.3
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• pp.15-25
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• 2005

Ninety tow percent of over 1,800 gate controlled dams in Korea are classified as small dams. The primary purpose of these small dams is to supply irrigation water. Therefore, while large dams can store as much as 80 percent of precipitation and thus are efficient to control flood, small dams are often lack of flood control function resulting in increased susceptibility drought and flood events. The purpose of this study is to develope a storage management model for irrigation dams occupying the largest portion of small dams. The proposed Storage Management Model (STMM) can be applied to the Seongju dam for efficient management. Besides, the operation standard is capable of analyzing additional available water, considering water demand and supply conditions of watershed realistically. And the model can improve the flood control capacity and water utilization efficiency by the flexible operation of storage space. Consequently, if the small dams are managed by the proposed Storage management model, it is possible to maximize water resources securance and minimize drought and flood damages.

• Journal of Applied Reliability
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• v.1 no.2
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• pp.121-138
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• 2001

Due to large demand for high speed and great capacity for data transfer, WDM, which uses the wavelength division multiplexing technique, is known as alternative way to satisfy those demand for its flexible network operation and management, easy network expansion with existing networks, and enhancement of efficient data transfer rate. For these reasons, a new high capacity WDM optical communication network plan was established. Therefore, the quality of currently deployed optical cables with 81.6 km in length should be assessed to ensure if high capacity WDM system could be implemented on existing optical cables. Two important characteristic parameters, Transfer Loss and PMD (Polarization Mode Dispersion), were measured to evaluate quality of existing optical cable. Transfer Loss was measured at 0.244 dB per kilometer, which is lower than the design standard value at 0.275 dB/km. The measured PMD value gave at 0.030ps/km, and it, therefore, satisfies the value recommended by ITU-T (International Telecommunication Union-T) of 0.5ps/km. In addition, the transfer characteristic for existing 2.5 Gbps and 10 Gbps system were measured and evaluated, and the results showed that error-free transfer is very much feasible. Computer simulation for DWDM system, which is likely be a future backbone network in Korea, to assess the transfer characteristic using the same condition employed for 2.5 Gbps and 10 Gbps was carried out as well. The simulation verified that a stable network operation and reliable service could be provided.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2006.11a
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• pp.134-137
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• 2006

Satisfying the customer orders with a short lead-time is one of the essential and competitive factors for business units under a mass customization environment. To shorten the lead-time for fulfilling various orders entails the production capacity expansion and efficient operational policy. Most business firms utilize the multiple production lines or facilities to cope with this business and manufacturing environment by making the manufacturing and distribution more flexible. In this study, we introduce the operational problem determining the joint production and delivery policy in an environment where multiple products are manufactured with more than one production lines. Also, we propose the heuristic solution approach for determining the product-line selection and joint lot size for this problem.

• Journal of the Korean Operations Research and Management Science Society
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• v.17 no.1
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• pp.43-54
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• 1992

This paper discusses a real time production control system of a FMS (Flexible Manufacturing System). The control is organized in a hierarchical structure according to the various decisions at the different time scales. In the earlier work-set-up time was not considered. Because the capacity of the toll magazine is limited, this assumption may not be adequate for selecting times to change configurations so that new part family can be produced. The goal of the control system is to meet production requirements while the machines fail and are repaired at random times. In this thesis the machien failure and set-up are considered simultaneously. Here the hedging point of this system is calculated, and the formulation of the dynamic control for FMS that has unreliable machines with set-up suggested.

• Asia pacific journal of information systems
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• v.5 no.1
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• pp.186-218
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• 1995

The necessity of installing well adaptable Information Systems are required day by day in all the fields of business management. This paper provides an Information System development for enhancing competitive power of the small and medium-sized firms in Korea. Recent growing Information Technology leads to constructing invisibly some new adaptable Information Systems in accordance with the business size, level, capacity and requirements. Even though some advanced companies and big enterprises are already operating their own appropriate Information Systems so as to get their remarkable productivity at a moment. The rest of those small firms are still trying to find out some proper systems fitting their own business in very poor situations. The basic requirements of the points of views by mail questionaired and interviewed from 1292 small and medium-sized manufacturing firms reflected on this Information System development. As a result, the study introduces some economically efficient, convinient, flexible and useful applied Information Systems with simple methods.

• Journal of Electrical Engineering and Technology
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• v.11 no.2
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• pp.274-284
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• 2016

The increasing penetration of distributed energy resources on the distribution networks have brought a number of technical impacts where voltage and thermal variations have been identified as the dominant effects. Active network management in distribution networks aims to integrate distributed energy resources with flexible network management so that distributed energy resources are organized to make better use of existing capacity and infrastructure. This paper propose active solutions which aims to solve the voltage and thermal issues in a distributed manner utilizing a collaborative approach. The proposed algorithms have been fully tested on a distribution network with distributed generation units.

• IEMEK Journal of Embedded Systems and Applications
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• v.16 no.4
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• pp.153-161
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• 2021

Real-time access is required to handle continuous and unstructured data and should be flexible in management under dynamic state. Platform can be built to allow data collection, storage, and processing from local-server or multi-server. Although the former centralize method is easy to control, it creates an overload problem because it proceeds all the processing in one unit, and the latter distributed method performs parallel processing, so it is fast to respond and can easily scale system capacity, but the design is complex. This paper provides data collection and processing on one platform to derive significant insights from various data held by an enterprise or agency in the latter manner, which is intuitively available on dashboards and utilizes Spark to improve distributed processing performance. All service utilize dockers to distribute and management. The data used in this study was 100% collected from Kafka, showing that when the file size is 4.4 gigabytes, the data processing speed in spark cluster mode is 2 minute 15 seconds, about 3 minutes 19 seconds faster than the local mode.

• Archives of design research
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• v.13 no.3
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• pp.303-312
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• 2000

Identity Design System, based on the principle of market economy, has developed over last half a century. The essence of identity program is to establish the corporate Image from dispersion to integral ion through design. There is no doubt that identity design became an inevitable necessity as a market In tool . The circumstance of corporate identity, however , has been changed since the revolution of telecommunication by computer which had an important effect upon today's market The development of computer communication allows people with different taste to achieve their needs from var ious kinds of information. Today's market is shitting from uniformity to diversity It is more difficult to create a corporate Image through conventional method. To meet the challenges of today's market, the communication of corporate identity will ultimately reflect the complexity of the market by adapting the flexible conoept of identity design. The level of flexibility in identity system should be determined depending on the management and market Eng strategy. Flexible Identity System (FIS) would be the best solution for some cases such as; a company with various fields, a company with sensitivity to the contemporary trend, and a company with an emotional appeal to consumers. FIS, with the capacity of a chameleon, can not only adopt the various circumstantial flanges, but also maintain the up-to-date corporate image .