• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.7A
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• pp.629-634
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• 2002

The next generation of wireless communication system is expected to provide users with wireless multimedia services such as high speed internet access and wireless mobile computing. Depending on the Quality of Service(QoS) requirements and different applications per user, many wireless communication systems have been proposed. The simple decoding algorithm of space-time block coding is based on the assumption of flat fading channel, where no intersymbol interference exists. In this paper, we propose to combine space-time transmit diversity with adaptive equalizer. The proposed system effectively eliminates interference caused by multipath environment. Simulation results show that the proposed system provides improved bit error rate performance.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.19 no.12
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• pp.2328-2339
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• 1994

The PBS(Partial Buffer Sharing) space priority mechanism is one of priority control methods which may improve the performance of a single server queueing system when mixed traffic with different performance requirements is applied to the system. This paper analyzes the cell loss behavior of PBS assuming loss sensitive traffic and delay sensitive traffic are applied to the system. To derive the successive cell loss probabilities. which are an important performance measure of realtime traffic, we develop a recursive algorithm. Performance results show the successive cell loss probabilities obtained by our method are lager than the probabilities derived from an independent cell loss assumption. These results may indicate the limitation of PBS for realtime traffic and the increase of the admissible load with the criterion of quality of service.

• Journal of the Korean Institute of Educational Facilities
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• v.8 no.4
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• pp.5-15
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• 2001

The purpose of this study is to clarify the using condition and requirement for outdoor space between the parallel types of elementary school buildings focused on Chungbuk province in Korea. Consequently, we investigated the actual conditions of students and teachers, using conditions of outdoor space between school buildings. The summary of outdoor space can be given below. 1) In the using condition of outdoor spaces, most of them have path & covered walks, garden, playground and soon. The distances between neighboring building fixed, the use and quality of outdoor space is differently to spatial configuration of school buildings. For example, garden functions as itself in case of D/H>3, but the other space to observe in D/H>3. 2) In the requirements of outdoor spaces, the amount of scatter number of classmates and teachers is wide. The favoring outdoor space is the woods to take a rest by oneself, the demanding outdoor space is almost a resting place like a school store in case of classmates and the natural facilities like ponds garden pagora in teachers.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2015.05a
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• pp.7-8
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• 2015

Formwork accounts for 10% of the total construction cost and 30~40% of the framework cost, which is a fairly large part. Various system forms were developed for improved economic feasibility and constructability of formwork and for reduced construction duration. In general, the price of system forms per unit area is higher than that of the conventional method, yet the total construction cost can be reduced through higher reusability and constructability. However, if the reusability of forms is excessively increased to cut down the material cost, it may increase the construction duration, which will result in cost increase. On the other hand, if the reusability is decreased for reduction of construction duration, it may lead to cost increase caused by excessive input of materials. To solve such a problem, an algorithm for simplified reuse planning that meets the requirements of construction duration, cost, quality and safety is required. In this regard, the study intends to perform a fundamental research for development of reuse planning automation algorithms on system forms that are used on girders and beams.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.7C
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• pp.548-553
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• 2008

To reduce the bit-rate requirements imposed by a network or satisfy processing limitations imposed by a terminal, Conversion the temporal resolution of a video bit stream is a technique that may be used. This paper discusses the problem of reduced resolution transcoding of compressed video bit streams, and discussed the technique for temporal transcoding. To speed up this operation, a video transcoder usually reuses the coded motion vectors from the input video bit stream. In this paper we propose an enhanced motion re-estimation technique to maintain higher quality of coded frames. The performance of experimental results can be improved while maintaining low computational complexity for a reduced frame rate video transcoder.

• Journal of Information Technology Applications and Management
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• v.20 no.3
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• pp.43-59
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• 2013

In order to realize the benefits of ITSM, it is necessary to institutionalize ITSM into the organizational culture. Currently, efforts to routinize ITSM lack in practice, and research in this area is also lacking. This study identifies the factors affecting the routinization of ITSM through literature review and interviews with experts, selects a company that has successfully routinized ITSM, and analyses the activities, methods, and procedures employed by the company on the factors in detail. The specific factors analyzed in the study include fulfillment of the customer requirements, top management support, communication, change management, training and education, quality of the ITSM system, and capability of the personnel. Important points verified in this study is that in order to realize organizational performance from ITSM, just the adoption of ITSM is not enough, but the routinization of ITSM through continuous and systematic management and improvement with the support of top management are required. Since this study is a descriptive case study, results of the study cannot be generalized. However, the study will provide practical information that can be referenced by the organizations attempting to routinize ITSM. In addition, results of the study will provide a basis of future research in ITSM.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2000.11a
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• pp.245-248
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• 2000

Modern aircraft composite structures are designed using a damage tolerance philosophy. This design philosophy envisions sufficient strength and structural integrity of the aircraft to sustain major damage and to avoid catastrophic failure. The only reasonable way to treat on the same basis all the conditions and uncertainties participating in the design of damage tolerant composite aircraft structures is to use the probability-based approach. Therefore, the model has been developed to assess the probability of structural failure (POSF) and associated risk taking into account the random mechanical loads, random temperature-humidity conditions, conditions causing damages, as well as structural strength variations due to intrinsic strength scatter, manufacturing defects, operational damages, temperature-humidity conditions. The model enables engineers to establish the relationship between static/residual strength safety margins, production quality control requirements, in-service inspection resolution and criteria, and POSF. This make possible to estimate the cost associated with the mentioned factors and to use this cost as overall criterion. The methodology has been programmed into software.

• Journal of the Korea Society of Computer and Information
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• v.18 no.2
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• pp.59-68
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• 2013

Efficient resource management and hand-over schemes are necessary to maintain consistent QoS because it may be severely defected by some delay and information loss during hand-over in LTE-Advanced networks. This paper proposes a resource management scheme based on the load control to support consistent QoS for heterogeneous services during hand-over in OFDMA based systems. Various multimedia services with different requirements for resource are able to be serviced simultaneously because service continuity can be provided by our proposed scheme. Simulation results show that it provides better performances than the conventional one with the measure of hand-over failure rate and packet loss rate.

• Journal of Institute of Control, Robotics and Systems
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• v.11 no.8
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• pp.726-732
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• 2005

This paper proposes an autolanding guidance and control algorithm with the lateral guidance law. This algorithm is basically formulated and designed in feedback linearization based on singular perturbation. Main features of this algorithm are two facts. One of those is that when a certain situation happens that airplane must realign to the runway suddenly assigned due to unexpected environment change around the landing site, the heading guidance in this algorithm is very valuable, and the other is the fact that the inner loop control of this algorithm is able to be designed directly based on the Handling Quality Requirements that most flight control systems must be satisfied with. To illustrate the potential of this algorithm, 6-DOF nonlinear simulation based on the nonlinear airplane model shown in Ref.[11] is carried out. The simulation results showed that the altitude response to the given landing trajectory is accurate, and the airplane heading alignment to the assigned runway from the lateral deviation is successful. It is noted that this algorithm is also applicable to unmanned aerial vehicle, which can be retrieved in autolanding technique, where the runway far retrieving the vehicle is in any direction for example at war field.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.11 no.4
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• pp.83-89
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• 2011

Nowadays, Internet Telephony Services based on SIP are gaining an explosive increase for general user. Thus a various demands of the user about convenience of IP-PBX are growing. The most important requirements of these is hybrid IP telephony system which is connected not only internet telephone but also general PSTN telephone. Therefore, in this paper, we have developed Hybrid IP-PBX connected all type of telephony terminals for small office. We have developed FXS module for connecting all type and FXO for using PSTN telephone number also. This Hybrid IP-PBX that is can be connected Soft-phone provide various optional services. We measured voice quality and test simultaneous calling for proof of validity.