• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.7C
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• pp.666-674
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• 2005

A hybrid multicarrier CDMA/FDM system with a truncated adaptive transmission scheme is analyzed in forward link based on the feedback information from the mobile station. In the single cell environment, the prop(mea scheme outperforms the adaptive FH/DS system as well as the MC DS/CDMA system when orthogonal signature sequences are used. In the multiple cell environment also, the proposed scheme has better performance characteristics than the adaptive FH/DS system when orthogonal and random codes are used as spreading sequences.

• Journal of Fashion Business
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• v.27 no.6
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• pp.147-159
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• 2023

Fashion is the second most polluting industry. We must strive to transition to a form of industry that does not cause environmental pollution. These efforts drive may fashion brands to produce and sell products with redesigned methods that delight the inventory flow. Accordingly, it is necessary to develop creative apparel up-cycling design using the creative thinking method. This study aims to produce clothing redesign works by introducing design idea types for systematic redesign creation. In this research, we conducted a literature review on the concept of up-cycling design and employed heterotopa spacial concept reflected fashion design creation methodology types. The RE;CODE, a leading domestic up-cycling design brand, was used in case analysis. According to the command of shape transformation, it is spreading, stacking, dropping, inverting and crossing, from the creative thinking method reflecting heterotopia spacial concepts, showing designers a concrete way to transform form into new apparel. Seven works of apparel up-cycling design were developed by conducting process of RE;CODE. Also, to establish an apparel up-cycling design creation process for creating works. In this study, we proposed a systematic method for apparel up-cycling design, including a method for reorganizing two or more different materials to create something new and ultimately reversing the structure. The value and significance of this study is that it proposes a systematic method for apparel up-cycling design to make it new.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.23 no.5
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• pp.1173-1183
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• 1998

This paper proposes an SS-PRMA protocol for the integrated voice and data services in the packet radio networks. In this protocol, the uplink logical channels are provided by combining the time slots and the spreding codes. SS-PRMA protocol contains some features of existing protocols such as PRMA, slotted ALOHA, and CDMA. In the proposed protocol, the voice terminals use a reservation mechanism, and the dta terminals use a slotted ALOHA scheme. The analysis and the simulation results show that most of the performances for the voice traffic can be achieved by employing a few distinct spreading codes and the data traffic throughput is closely related to the number of spreading code channels. Also it shows that the data traffic performance can be significantly improved by applying an FEC scheme to the data link layer.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.19 no.5
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• pp.971-980
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• 1994

The need increased capacity in the cellular system has resulted in the adoption of digital technology with CDMA as the channel access method. It has been recognized that the distinction of the base station is important for its performance in CDMA, since the same spreading sequences are used by the all base stations. Time offset of the pseudo-random noise binary code are used to distinguish signals received at a mobile station from different base station. But the start of the zero offset PN sequence is chosen arbitrary without the background of the systematic and mathematical elaboration. This paper proposes a mothed that define the start of the zero offset PN sequence mathematically. This paper also discusses a method that can easily calculate the time offset of the received spreading sequence with respect to the zero offset PN sequence.

• Journal of the Institute of Electronics Engineers of Korea TE
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• v.37 no.1
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• pp.58-62
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• 2000

We Propose modulation scheme using I-Q modulation for transmitting different information simultaneously. For transmitting 1bit of each information, we apply QPSK scheme, for more bits, MAPSK. At the second modulation stage, We mix PN wavefoms with APSK waveforms for spreading bandwith. BER(Bit Error Rate) of each Information of the proposed scheme is analyzed on computer simulation. Finally we show power spectrum before and after spreading bandwidth.

• Journal of Communications and Networks
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• v.7 no.1
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• pp.21-28
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• 2005

In this paper, we analyze the performance of code division multiple access (CDMA) systems with orthogonal frequency division multiplexing (OFDM) that employ random spreading sequences in an additive white Gaussian noise (AWGN) channel. We obtain the probability density function (pdf) of the multiple access interference and extend the results to OFDM-CDMA systems to determine the pdf of multiple access and inter-carrier interference in terms of the number of users, the spreading length, the number of sub-carriers, and the frequency offset. We consider the synchronous downlink of cellular multi-carrier CDMA and derive a Gaussian approximation of the multiple access and inter-carrier interference. Overall the effect of frequency offset is shown to vary with the system loading. The analysis in this paper is critical for further development into fading channels and frequency selective multipath channels.

• Proceedings of the Korea Institute of Fire Science and Engineering Conference
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• 1997.11a
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• pp.305-310
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• 1997

There are many parameters in prediction of forest fire spread. The variables such as fuel moisture, fuel loading, wind velocity, wind direction, relative humidity, slope, and solar aspect have important effects on fire. Particularly, wind and slope factors are considered to be the most important parameters in propagation of forest fire. Generally, slope effect cause different wind distribution in mountain area. However, this effect is disregarded in complex geometry. In this paper, wind is estimated by applying computational fluid dynamics to the forest geometry. Wind velocity data is obtained by using CFD code with Newtonian model and slope is calculated with geometrical data. These data are applied fer 2-dimentional forest fire spreading algorithm with Korean ROS(Rate Of Spread). Finally, the comparison between the simulation and the real forest fire is made. The algorithm spread of forest fire will help fire fighter to get the basic data far fire suppression and the prediction to behavior of forest fire.

• Journal of the Korea Society of Computer and Information
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• v.14 no.9
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• pp.47-54
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• 2009

Malicious codes, which are spread through WWW are now evolved with various hacking technologies However, detecting technologies for them are seemingly not able to keep up with the improvement of hacking and newly generated malicious codes. In this paper, we define the requirements of detecting systems based on the analysis of malicious codes and their spreading characteristics, and propose an improved detection scheme which monitors HTTP Outbound traffic and detects spreading malicious codes in real time. Our proposed scheme sets up signatures in IDS with confirmed HTML tags and Java scripts which spread malicious codes. Through the verification analysis under the real-attacked environment, we show that our scheme is superior to the existing schemes in satisfying the defined requirements and has a higher detection rate for malicious codes.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.4B
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• pp.291-297
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• 2002

Due to the increasing demand for high data multimedia service, there has been progressing study of adaptive smart antenna to increase both the performance and capacity using limited wireless resource. IS-95 scheme in the origin of cdma2000 of IMT-2000 standard uses signals of spreading and Walsh-Orthogonal Modulation in reverse link. But, in the case of reverse lint there exists difficulty in synchronous of signals transmitted from users. Therefore, orthogonality between users is not satisfied. So, asynchronous MC-CDMA scheme may yield low performance. In this paper, MC/DS-CDMA scheme to reverse link transmission in adaptive array antenna environment is proposed for spreading the S/P-converted data streams using a given spreading code. Due to frequency diversity effect, simulation results show that the proposed system provides improved BER performance and narrow band interference supple psi on.

• Journal of KIISE:Information Networking
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• v.29 no.2
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• pp.141-155
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• 2002

A medium access control protocol is proposed for integrated voice and data services in the packet CDMA network with a small coverage. Uplink channels are composed of time slots and multiple spreading codes for each slot. This protocol gives higher access priority to the delay-sensitive voice traffic than to the data traffic. During a talkspurt, voice terminals reserve a spreading code to transmit multiple voice packets. On the other hand, whenever generating a data packet, data terminals transmit a packet based on the status information of spreading codes in the current slot, which is received from base station. In this protocol, voice packet does not come into collision with data packet. Therefore, this protocol can increase the maximum number of voice terminals.