• Korean Journal of Human Ecology
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• v.13 no.5
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• pp.787-798
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• 2004

This research was designed to compare clothing fabric images between on- and off-line by fabric types and its characteristics. 125 subjects who have a fashion design major evaluated the fabric image of various 16 kinds of specimens on- and off-line. Frequency, x2-test, t-test, and Pearson correlation were used for statistical analysis by SPSS WIN 11.0. The results of this study are as follows: 1. The advantage of on-line shopping includes low price and purchasing convenience, etc. On-line shoppers mostly purchase clothing items, such as T-shirt and slacks. In most cases, texture of fabrics provides a main cause for the shoppers' discontentment with internet shopping. 2. The results of t-test for the difference of the evaluation score show that plain or pile weave and highly thick or thin fabrics-for example, Organdy, Corduroy, Nylon Taffeta, Plush, etc.-have a large difference between on-and off-line image. On the other hand, medium-thick twill weave-for example, Tweed, Flannel, etc.-or patterned weave-Chiffon, Dobby fabric, etc.-shows a small difference. 3. The results of correlation of the evaluation score indicate that wool twill fabrics like Tweed, Saxony, and Polafleece show a high correlation between two kinds of evaluation score. In texture preference, no correlation exists between on-line and off-line. 4. With an analysis on fabric image evaluation by fabric characteristics, smooth, shiny pink Satin was found the most positively-evaluated item in all evaluation fields except in pattern preference and individuality. On the other hand, thick olive green Corduroy was evaluated most negatively in the fields of elegance, luxury, and feminine. 5. When compared with real ones, thin fabrics provide a different on-line fabric image. For example, Nylon Taffeta and Organdy were evaluated positively on-line because of luster and pastel tone color. However, lusterless uneven cotton Seersucker was evaluated negatively. 6. Real fabrics preference is more negative than on-line ones. In addition, patterned or unique fabrics display a high agreement between the two kinds of images.

• Journal of KIISE:Information Networking
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• v.29 no.6
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• pp.595-612
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• 2002

One of the most important issues in guaranteeing the high degree of QoS on mobile computing is how to reduce hand-off drops caused by lack of available bandwidth in a new cell. Each cell can request bandwidth reservation to its adjacent cells for hand-off calls. This reserved bandwidth can be used only for hand-offs, not for new calls. It is also important to determine how much of bandwidth should be reserved for hand-off calls because reserving too much would increase the probability of a new call being blocked. Therefore, it is essential to develop a new mechanism to provide QoS guarantee on a mobile computing environment by reserving an appropriate amount of bandwidth and call admission control. In this paper. bandwidth reservation and call admission control mechanisms are proposed to guarantee a consistent QoS for multimedia traffics on a mobile computing environment. For an appropriate bandwidth reservation, we propose an adaptive bandwidth reservation mechanism based on an MPP and a 2-tier cell structure. The former is used to predict a next move of the client while the latter to apply our mechanism only to the client with a high hand-off probability. We also propose a call admission control that performs call admission test only on PNC(Predicted Next Cell) of a client and its current cell. In order to minimize a waste of bandwidth caused by an erroneous prediction of client's location, we utilize a common pool and QoS adaptation scheme. In order evaluate the performance of our call admission control mechanism, we measure the metrics such as the blocking probability of new calls, dropping probability of hand-off calls, and bandwidth utilization. The simulation results show that the performance of our mechanism is superior to that of the existing mechanisms such as NR-CAT2, FR-CAT2, and AR-CAT2.

• Proceedings of the Korean Information Science Society Conference
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• 2002.04a
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• pp.544-546
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• 2002

최근 무선 통신 기술이 빠르게 발전하면서, 모바일 사용자들의 다양한 서비스에 대한 요청이 증가하고 있다. 그리고 멀티미디어 서비스는 네트웍 효율성의 측면에서 멀티캐스트 전송 기법이 적합하다. 이에, IETF Working Group에서는 이동 컴퓨팅 환경에서 IP 멀티캐스트를 지원하기 위해 Home Subscription 과 Remote Subscription을 제안하였다[1]. 이 방법들은 각각 장.단점을 가지고 있으나, 호스트에게 연속적인 서비스를 제공하지는 못한다. 본 논문에서는 Remote Subscription에서 제공하는 최적의 경로를 사용하면서, 사용자들에게 멀티캐스트 상에서 연속적인 서비스를 제공할 수 있는 방안에 대해 제시한다. Multicast Agent는 자신이 관리하는 네트웍에 현존하는 사용자들의 멀티캐스트 그룹의 관리와 사용자들을 대신하여 그룹에 가입 및 탈퇴를 행한다. 본 논문에서 제시한 방법은 이동 가능한 지역의 Multicast Agent가 미리 멀티캐스트 그룹에 참가함으로써 기존의 제시된 연구 방법들에 비해 사용자들에게 연속적인 서비스를 제공할 수 있다.

• Journal of Korean Institute of Industrial Engineers
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• v.41 no.4
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• pp.330-337
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• 2015

A bucket-brigade is a way of transporting items where items are passed from one person to the next. The operation of the bucket brigade imitates the cooperative behavior of ants when brood, food or other resources are moved. Koo (2009) presented a bucket brigade-based assembly cell where each worker follows a simple rule: perform assembly operations on a product until the next worker downstream takes it over; then go back to the previous worker upstream to take over a new assembly job. In this way, the flow line is self-balanced without any predetermined job assignment. However, there are some productivity losses related to hand-off and blocking. This paper examines the hand-off and blocking losses and presents a new bucket brigade-based assembly cell where working areas for each assembler is restricted with the help of buffer interfaces. Simulation experiments are used to validate the performance of the new assembly system.

• Proceedings of the Korea Information Processing Society Conference
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• 2003.11b
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• pp.1153-1156
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• 2003

무선네트워킹의 급격한 확대와 휴대가 간편한 이동단말의 보급이 증가함에 따라 QoS와 이동성이 보장된 IP Telephony 서비스가 필요하게 되었다. 무선인터넷을 이용하는 Voice over IP 서비스는 IP 기반의 인터넷과 셀룰러 네트워크를 합쳐 놀은 것과 유사하며 모바일 노드의 이동성 확보가 핵심 기술이다. 특히 전화서비스의 이용자는 Web이나 FTP같은 데이터 기반의 서비스에 비하여 지연이나 끊어짐에 매우 민감하므로 가급적 지연시간이 적은 핸드오프 기법이 필요하다. 본 연구에서는 무선네트워킹을 이용하는 VoIP 서비스 프로토콜 중 하나인 SIP(Session Initiation Protocol)를 기반으로 이동성 관리를 위한 신호의 흐름과 발생 가능한 지연의 구성요소를 분석하였다. 또한 핸드오프 지연을 줄이기 위한 유용한 기법이지만 신호 트래픽을 과다하게 발생시키는 Shadow Registration에 예측기법을 적용하여 핸드오프 지연을 감소시키면서도 신호 트래픽을 최소화하는 PSR(Predictive Shadow registration) 기법을 제안하였다.

• Proceedings of the Korean Information Science Society Conference
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• 2000.04a
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• pp.460-462
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• 2000

무선 이동통신 네트워크 환경에서는 제한된 네트워크 대역폭과 모바일 호스트(Mobile Host)의 잦은 이동성에 기인한 핸드오프(Hand-Off)로 인하여 다양한 종류의 트래픽(Traffic)에 대한 QoS(Quality of Service)를 보장하기가 용이하지 않다. 그러나, 이렇게 예측하기 힘든 다양한 특징을 가지는 무선 이동통신 네트워크 환경에서도 특정 종류의 트래픽, 예를 들자면 실시간 트래픽(Real-time Traffic)에 대하여 요구된 범위 내에서의 QoS(Quality of Service)가 반드시 보장되어야 한다. 본 논문에서는 모바일 호스트의 이동성을 제공하는 차세대 무선 이동통신 네트워크, 즉 2.5 세대라 불리는 IS-2000 무선 네트워크에서 다양한 종류의 실시간 트랙픽에 대해 QoS를 보장하기 위한 개선된 레져베이션 프로토콜(Advanced Reservation Protocol) 및 GPS 베이스드 (Global-Positioning-System Based)핸드오프 프리딕션 (Hand-Off Prediction) 알고리즘을 제안하였다.

• Proceedings of the IEEK Conference
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• 2006.06a
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• pp.87-88
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• 2006

In this paper, we propose a new selective scanning scheme based on hand-off path information, which can provide an efficient reducing of delay time. This scheme eliminates almost of the scanning delay time by using Selective Scan based on Experience Path Table(SSEPT) algorithm and also completed hand-off within few milliseconds by using the next candidate channel indexing mechanism. Our scheme reduces the total number of scanning channels as well as the delay time on each channel. From the simulation result, we show that the proposed scheme is advantageous over the legacy schemes in terms of the scanning channels and the total delay time.

• ETRI Journal
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• v.28 no.3
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• pp.379-382
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• 2006

A novel reconfigurable microstrip patch antenna with frequency and polarization diversities is proposed. A U-slot is incorporated into a square patch, and a PIN diode is utilized to switch the slot on and off, which realizes the frequency diversity characteristic. The polarization diversities among linear polarization (LP), right-hand circular polarization (RHCP), and left-hand circular polarization (LHCP) are also obtained by switching three PIN diodes on the slot and the truncating corners of a square patch on and off. The antenna design and experimental results are presented.

• Proceedings of the KSR Conference
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• 2008.11b
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• pp.1138-1144
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• 2008

To study the feasibility of applying wireless communication technology to the control of train for the effective control of train and for the reduction of cost and time to construct the necessary infra structure, we investigate into the application of the existing commercial WCDMA network to CBTC (communication-based train control) to grasp the obstacles and propose the solutions to circumvent them. The obstacles can be categorized into the hand-off problem, the interference problem near the stations, and the problem of radio shadow areas. We propose, as solutions, the cell overlap method and multi-terminal approach for the hand-off problem, the cell sectoring method for the interference problem, and establishment of new base stations along the railroad both to provide the wireless train control and communication service to the customers on the train which was otherwise impossible because of the shadowing effect.

• Proceedings of the Korean Society of Computer Information Conference
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• 2021.07a
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• pp.485-486
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• 2021

항공기에는 많은 시스템이 있고 다양한 장치들이 있다. 이 장치들은 사용자의 명령을 입력받아 사용되는데 자동을 제외한 거의 모든 시스템들은 사용자의 직접적인 조작으로 작동된다. 하지만 여전히 완전 자동화는 되지 않아 사소하고 섬세한 부분에서 조종사는 수동으로 작동시켜 주어야하는 부분들이 있다. 사소한 부분들을 신경써야 하기에 조종사에게 피로는 필수적을 따라왔다. 본 연구에선 현재의 기술에서 더 나아가 음성인식(STT, TTS)을 활용하여 항공기의 다양한 장치들을 원격제어할 수 있게 개발하여 완전 자동화를 목적으로 한다. 음성을 이용한 방식은 조종사에게 손을 사용하지 않는 편리함을 제공한다. 조종사에게 원거리에서 음성으로 조작할 수 있게 해줌으로써 손을 사용하여 조작하지 않아 편의성을 제공할 수 있고 명령을 통해 컴퓨터가 처리함으로써 조종이 간단해진다. 본 연구로 인해 사소한 부분까지 신경쓸 필요가 없어져 조종사의 실수나 피로로인해 일어나는 사고를 방지할 수 있다.