• Journal of the Korean Operations Research and Management Science Society
• /
• v.23 no.3
• /
• pp.135-151
• /
• 1998

The demand of large capacity in coming cellular systems makes inevitable the deployment of small cells, rendering more frequent handoff occurrences of calls than in the conventional system. The key issue is then how effectively to reduce the chance of unsuccessful handoffs, since the handoff failure is less desirable than that of a new call attempt. In this study, we consider the control policies which give priority to handoff calls by limiting channel assignment for the originating new calls, and allow queueing the new calls which are rejected at their first attempts. On this system. we propose the problem of finding an optimal call control strategy which optimizes the objective function value, while satisfying the requirements on the handoff/new call blocking probabilities and the new call delay. The objective function takes the most general form to include such well-known performance measures as the weighted average carried traffic and the handoff call blocking probability. The problem is formulated into two different linear programming (LP) models. One is based on the direct employment of steady state equations, and the other uses the theory of semi-Markov decision process. Two LP formulations are competitive each other, having its own strength in the numbers of variables and constraints. Extensive experiments are also conducted to show which call control strategy is optimal under various system environments having different objective functions and traffic patterns.

• International Journal of Quality Innovation
• /
• v.6 no.2
• /
• pp.59-89
• /
• 2005

Manufacturing Resources Planning (MRPII) is one kind of manufacturing information system that can help manufacturing companies gain competitive advantages. It is estimated that more than one hundred MRPII systems are available in the market, many of them are mature enough to solve most operational issues in accordance with users' requirements. More often than not, many of these systems provide more functions than a company expects. Manufacturing companies worldwide have attempted to implement these MRPII systems, however, many companies experienced failure (Turbide, 1996) due to managerial rather than technical issues. The authors propose an approach utilising a roadmap to integrate BPR and the MRPII implementation in order to overcome this difficulty. A detail road map is developed to guide this implementation, which is designed using a hierarchical analysis technique known as Integrated DEFinition Method (IDEF). IDEF is a systematic manufacturing management and integration-modeling tool. The proposed approach is implemented and illustrated using a reference company and the results indicated that 66% reduction in errors for maintaining the bills of materials system; 99% reduction in time to carry out material requirement planning; and 70% reduction in time previously taken for non-productive discussions.

• The Journal of Internal Korean Medicine
• /
• v.20 no.1
• /
• pp.73-82
• /
• 1999

Nitric oxide (NO) is now recognized as a mediator of several biological and immunological functions, but unlike classical neurotransmitters. NO simply diffuse of the postsynaptic cells and around affecting cells. Taraxacum officinale (Compositae) has been used for maintenance of vitality, and they still occupy an important place in the traditional Korean medicine. We have examined that the effect of Taraxacum officinale water extract on NO synthesis in microglial cells of murine's brain, using the Griess method. And this study was evident that Taraxacum officinale did not induce NO production without recombinant interferon gamma ($rIFN-{\gamma}$), whereas Taraxacum officinale (10-1000 g/ml) with $rIFN-{\gamma}$ effectively produced NO in microglial cells of brain. As result. NO production in microglial cells increased most significantly in dose of 100 g/ml of the Taraxacum officinale and the production of NO was dependent on the dose of Taraxacum officinale, NG-monomethyl-L-arginine, competitive inhibitor of NO synthase, reduced the NO production by Taraxacum officinale stimulation with $rIFN-{\gamma}$ in microglial cells of murine. The effect of Taraxacum officinale was mainly dependent on Taraxacum officinale-induced tumor necrosis factor- secretion. Conclusively, this study suggested that Taraxacum officinale stimulate NO production at microglial cells in brain, which may be an important factor for mediating immune and neuroendocrinologic regulation in nervous system.

• Journal of the Korea Society of Computer and Information
• /
• v.8 no.1
• /
• pp.30-36
• /
• 2003

Korea has been issued on K4 Firewall Certificates for security, and these K4 Firewalls has been installing all Korean public organizer. In this paper, I would analysis process and functions of K4 Firewall. I had been created by difference and performance test between existing 32bit and latest 64bit K4 Firewall System on Solaris Operating System that wide use in Korea So that the result of improved more two times passed rate on 64bit than 32bit on Solaris K4 Firewall System At finally, I would conclude that the change direction will be useful for research and development on K4 Firewall System and Korean Firewall System which is a very competitive system in the world.

• Journal of Korean Society of Industrial and Systems Engineering
• /
• v.35 no.4
• /
• pp.194-201
• /
• 2012

Because the difference between products and services are getting less and less, service and manufacturing companies' efforts are increasingly focused on utilizing services to satisfy customers' needs under today's competitive market environment. The value of services depends on service reliability that is identified by satisfaction derived from the relationship between customer needs and service providers. In this paper, we extend concepts from the fault tree analysis for reliability analysis of tangible systems to services. We use an event-based process model to facilitate service design and represent the relationships between functions and failures in a service. The objective of this research is to propose a method for evaluating service reliability based on service processes using service blueprint and FTA. We can identify the failure mode of service in a service delivery process with a service blueprint. The fuzzy membership function is used to characterize the probability of failure based on linguistic terms. FTA is employed to estimate the reliability of service delivery processes with risk factors that are represented as potential failure causes. To demonstrate implementation of the proposed method, we use a case study involving a typical automotive service operation.

• Journal of Korean Society of Industrial and Systems Engineering
• /
• v.26 no.1
• /
• pp.7-16
• /
• 2003

At present, company has to produce a product that consumer like with a competitive price, a good quality, and a fitting time to supply. Process control and quality control are very important to supply with a product uniformly and inexpensively. Process control is given much weight in the quality control in manufacturing system. Statistical process controls(SPC) that are used in process generally have major impact on manufacturing, product design activities, and process development potentially. Control charts in statistical process control method can be interpreted the data from quality characteristics in production process and discriminated between chance variation and assignable variation in process. In addition, control chart can be used to monitor the process output and detect when changes in the inputs are required to bring the process back to an in-control state. The models that relate the influential inputs to process outputs help determine the nature and magnitude of the adjustments required. In this paper, the characteristic of product quality is monitored by control chart during the machining process and construction of quality control cycle is considered to divide into two types in this case that different assignable causes lead to shifts having different magnitudes. Then we are intended to find a process shift magnitude which has economical quality cost policy and are considered to quality cost functions to find a process shift magnitude. Those costs are categorized into the well-known categories of prevention, appraisal, and internal failure and external failure. This paper ends with numerical examples that demonstrate the usefulness of the model.

• Korean Management Science Review
• /
• v.24 no.1
• /
• pp.1-24
• /
• 2007

The function of product design has been an important part for success on new product development. We deeply studied 'Chocolate-Phone' case which is considered as a representative of adopting design-oriented new product development strategy. According to this study, we found three contextual factors and nine key success factors for design-oriented new product development. The contextual factors consist of the strong needs for innovative product development, customer's needs for the emotional value, competitive situation for the new product launching. The key success factors consist of design, development, marketing, overall sides. The key success factors of design side are to select talented designers and take an insight for market and communication skill. The key success factors of development side are to possess high technological abilities, to do divergence with removing or giving up some function, management's strong support. The key success factors of marketing side are to bring core marketers from outside, capacity to gather ideas from outside. The key success factors of overall side are to share design-oriented principle with other functions and to change member's mind from engineer-oriented to market-oriented.

• Proceedings of the ESK Conference
• /
• 1996.04a
• /
• pp.8-12
• /
• 1996

In many fields, the human sensibility ergonomics has applied to the product development for user's satisfaction. Also, it may use to lots of products and environments related to human convenient life. If the measurement and the validation of human sensibility are accomplished subjectively and qualitatively, then a good result is expected. Under the very competitive products development, designers applying with human sensibility ergonomics has faced with lots of problems including lack of experience, time, cost, and knowledge. In this study, a method of design for human sensibility application system is presented. In this study, a method of design for human sensibility application system is presented. Information element database such as adjectives, sensitivities, functions, and design factors is conducted, and design of system development including product development mechanism is produced. Also, the requirements and the specifications of this development model are discussed to develop the qualified implementation system.

• IEMEK Journal of Embedded Systems and Applications
• /
• v.10 no.5
• /
• pp.281-296
• /
• 2015

This paper describes a novel disaster evacuation system using embedded systems such as smart devices for crisis and emergency management. In indoor environments deployed with the Bluetooth Low Energy(BLE) beacons, smart devices detect their indoor positions from beacon messages and interact with Map Server(MS) and Route Server(RS) in the Internet over the LTE and/or Wi-Fi functions. The MS and RS generate an optimal path to the nearest emergency exit based on a novel graph generation method for less route computation, called the Disaster Evacuation Graph(DEG), for each smart device. The DEG also enables efficient processing of some constraints in the computation of route, such as load balancing in situation of different capacities of paths or exits. All data interfaces among three system components, the MS, RS, smart devices, have been defined for modular implementation of our disaster evacuation system. Our experimental system has been deployed and tested in our building thoroughly and gives a good evidence that the modular design of the system and a novel approach to compute emergency route based on the DEG is competitive and viable.

• Journal of Korea Society of Industrial Information Systems
• /
• v.4 no.2
• /
• pp.14-22
• /
• 1999

The great flowing of information has brought a necessity for good management to make the best use of it in the highly competitive information age. The aims of this study are to investigate the main information sources - divided into largely three groups : literature sources, communication and information technology facilities,), trying to find problem areas associated with IRM, indicating possible solutions. The result shows that internal information sources were regarded the most important and most frequently used. For the use of foreign materials, the higher the level of position is, the more people use them. With respect to communication methods, internal information sources were thought most important. With the dramatic falling of the price despite enormously increased functions, IT facilities are becoming important sources. However, the study reveals the use of them is quite limited to a few well-known facilities, witch indicates that management should pay attention to more efficient use of them and useful training and education methods.