• Journal of the Korean association of regional geographers
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• v.6 no.3
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• pp.83-99
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• 2000

This paper purposes to provide a new perspective for better development of geography texts. For this purpose, we have applied spatial cognition development theory to children's drawings. We have suggested that children's spatial operation ability has three development stages according to their age: topological space, projective space, euclidean space. This study turns out that Piaget and Inhelder's spatial concept development theory is on the right track. However, we make clear that their division according to the age is not always accurate due to children's individual differences. These findings have educational implications as the following: First, it is dubious that most children can understand pictures, pictorial maps and illustrations in the third grader's textbook. Second, current textbooks require pictorial map understanding and drawing to third grade students and map drawing to fourth grade students. However, according to this study, the placement of these tasks are not fit for children's developmental stage because both tasks correspond to euclidean space operation. Therefore, we should remove them from the textbook for children at the age.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.4 no.3
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• pp.643-652
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• 2000

In this paper, we analyze the BER performance of OFDM/QPSK system in frequency selective Rayleigh fading channel with impulsive noise and improve its performance by adopting convolutional coding. When the channel delay time is shorter than the guard band, the OFDM/QPSK system shows a good BER performance while, when the channel delay time becomes longer than the guard band, its BER performance is abruptly degraded. Moreover, when the transmitted signal is contaminated by a strong impulsive noise in the channel, the BER performance falls to about $10^{-1}$. Also, without channel coding technique, the system doesn't meet even the voice service requirement while it meets the data service requirement with convolutional coding in frequency selective Rayleigh fading channel with impulsive noise.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.2 no.4
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• pp.583-592
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• 1998

In this paper, the cell loss rate is analyzed in terms of the input traffic stream of different speed in ATM network. The cell loss rate is calculated by birth-death process of Leaky-Bucket mechanism as the representative algorithm of usage parameter control. The cell loss rate assumed 2-state MMPP input process to be birth-death process by considering the character of token pool about finite capacity queue. The results from numerical analysis show that the cell loss rate decreases abruptly according to the buffer size increase. The computer simulation by SIMSCRIPT II.5 has been done and compared with on/off input source case to verify the analysis results.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.4 no.3
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• pp.202-208
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• 2011

Recently the technologies that control the computer system through human computer interaction(HCI) have been widely studied. Their applications usually involve the methods that locate user's positions via face detection and recognize user's gestures, but face detection performance is not good enough. In case that the applications do not locate user's position stably, user interface performance, such as gesture recognition, is significantly decreased. In this paper we propose a new stable face detection algorithm using skin color detection and cumulative distribution of face detection results, whose effectiveness was verified by experiments. The propsed algorithm can be applicable in the area of human tracking that uses correspondence matrix analysis.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.3 no.3
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• pp.73-80
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• 2010

Complex-valued blind algorithms which are based on constant modulus error and Euclidian distance (ED) between two probability density functions show relatively poor performance in spite of the advantages of information theoretic learning since the inherent characteristics of the constant modulus error prevent the algorithm from coping with the symbol phase rotation caused by the complex channels. In this paper, we show that the symbol phase rotation problem can be avoided and the advantages of information theoretic learning can be preserved by introducing decision-directed mode to the blind algorithm whenever the equalizer output power lies in the neighborhood of multi-modulus levels. Simulation results through MSE convergence and constellation comparison for severely distorted complex channels show significantly enhanced performance of symbol-point concentration and no phase rotation problems caused by the complex channel models.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.2 no.2
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• pp.57-63
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• 2001

This paper aims at searching the attentiveness and method in planning. design and construction procedure of the container house system where container is used as core framework. For this. we try to produce researching fundamental materials for the construction performance and design standards of steel house, and finish the sample exterior wall system of the container house. By applying this sample system to the two case study of container housing construction we find out that there are considerable efnciency of the cost saving and catch up schedule compared with existing brick housing construction system. This study is significant in that it shows future direction of technical development and investment on the prefabricate housing market through development of the prefabricated container housing system.

• Journal of KIISE:Databases
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• v.27 no.2
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• pp.141-150
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• 2000

There are three significant drawbacks in extant fuzzy rule-based expert system languages. First, they lack the functionality of composite object inference. Second, they do not support fuzzy reasoning semantically easy to understand and conceptually simple to use. Third, knowledge representation and reasoning style of their model have a great semantic gap with those of current database models. Therefore, it is very difficult for the two models to be seamlessly integrated with each other. This paper provides the formal specification of a fuzzy object inference model to solve the three drawbacks. GIS(Geographic Information System) application domain is used to demonstrate that our model naturally models complex GIS information in terms of composite objects and successfully performs fuzzy inference between them.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.7 no.3
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• pp.384-389
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• 2003

A new two-step soft-output Viterbi algorithm (SOVA) decoder architecture is presented. A significant reduction in the decoding latency can be achieved through the use of the dual-port RAM in the survivor memory structure of the trace-back unit. The system complexity can be lowered due to the determination of the absolute value of the path metric differences inside the add-compare-select (ACS) unit. The proposed SOVA architecture was verified successfully by the functional simulation of Verilog HDL modeling and the FPGA prototyping. The SOVA decoder achieves a data rate very close to that of the conventional Viterbi Algorithm (VA) decoder and the resource consumption of the realized SOVA decoder is only one and a half times larger than that of the conventional VA decoder.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.8 no.3
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• pp.522-527
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• 2007

In this paper, we propose an error control coding scheme for constant-amplitude multicode-biorthogonal modulation. The product code is appropriate to the constant-amplitude multicode-biorthogonal modulation for the bit error rate performance improvement. In the constant-amplitude multicode-biorthogonal modulation, the vertical redundant bits are used for the constant amplitude coding. The proposed product code can be constructed by using the additional horizontal redundant bits. The hardware complexity of the encoder/decoder pair is very low. The simulation results show that the bit error rate performance of the proposed coding scheme is improve

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.12A
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• pp.975-982
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• 2003

A connection admission control scheme is proposed that can seamlessly support QoS in face of handoff in mobile packet networks. The proposed scheme is based on the adaptive time-selective bandwidth reservation with the reduced signaling and computational overhead. The reservation parameters are adjusted dynamically to cope with user mobility. Throughout the computer simulations, the performance of the proposed scheme is evaluated. As a result, it is shown that the proposed scheme reduces handoff call blocking probability remarkably, while other parameters (new call blocking probability and bandwidth utilization efficiency) are slightly deteriorated.