• Title/Summary/Keyword: interval system

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체계가용도의 붓스트랩 로버스트 추정

  • 홍연웅
    • Proceedings of the Korea Society for Industrial Systems Conference
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    • 1996.10a
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    • pp.205-210
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    • 1996
  • The bootstrap procedure is suggested as a useful method for point and interval estimation of system availability . Its validity and robustness has been shown in special , but representative case, by various sampling experiments. Alternative to the bootstrap suggest themselves (e.g. a variation of the 'F' technique, but remain to be evaluated, as do variations on the bootstrap itself.

A Study on Channel Equalization Technique for High-Speed Processing on DSRC System (DSRC 시스템에서의 고속처리를 위한 채널등화기법에 대한 연구)

  • Sung Tae-Kyung;Choi Jong-Ho;Cho Hyung-Rae
    • The Journal of The Korea Institute of Intelligent Transport Systems
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    • v.3 no.1 s.4
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    • pp.109-116
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    • 2004
  • The signal in wireless multi-path channel is affected by fading and ISI because of high data rate transmission, so the signal has the high error rate. The present modulation and demodulation method of DSRC system can not expect sufficient for providing data service over 1 Mbps, so the channel equalization and advanced modulation and demodulation methods are required. OFDM method is generally Inon as an effective technique for high data rate transmission system, since it can prevent ISI by inserting a guard interval. However, a guard interval longer than channel delay spread has to be used in each OFDM symbol period, thus resulting a considerable loss in the efficiency of channel utilization. Therefore the equalizer is necessary to cancel ISI to accommodate advanced ISI service with higher bit rate and longer channel delay spread condition. In this thesis, the channel equalizer for the OFDM-DSRC system was designed and its performance in a multi-path fading environment was evaluated with computer simulation. As a result, the performance of Pseudo LMMSE equalizer for the OFDM-DSRC has been improved comparing with LS equalizer at higher bit rate transmission system.

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Development of CFD Model for Estimation of Cooling Effect of Fog Cooling System in Greenhouse (온실 포그냉방시스템의 냉방효과 예측을 위한 CFD 모델의 개발)

  • 유인호;김문기;권혁진;김기성
    • Journal of Bio-Environment Control
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    • v.11 no.2
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    • pp.93-100
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    • 2002
  • This study was carried out not only to develop CFD model for numerically simulating fog cooling system but also to verify the validity of the developed model by data measured in fag cooling greenhouse. In addition the developed model was applied to investigate the effects of spraying water temperature, spraying water amount, spraying interval and evaporation percentage on the performance of the fog cooling system. According to the simulation results, the temperature differences between the measured and predicted temperatures at each measurement point were $0.1~1.4^{\circ}C$ in case of no shading and $0.2~2.3^{\circ}C$ in close of shading. The humidity differences were 0.3~6.0% and 0.7~10.6%, respectively in the cases of no shading and shading. Because the predicted data showed a good agreement with the measured ones, the developed model is supposed to be able to predict the cooling effect of the fog cooling system. The performance of fog cooling system was greatly influenced by spraying water amount, spraying interval and evaporation percentage, but it was not influenced by spraying water temperature.

Performance Analysis of OFDM-DSRC System Using LMMSE Equalization Technique (LMMSE 등화기법을 적용한 OFDM-DSRC 시스템의 성능분석)

  • Sung Tae-Kyung;Kim Soon-Young;Rhee Myung-Soo;Cho Hyung-Rae
    • Journal of Navigation and Port Research
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    • v.29 no.1 s.97
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    • pp.23-28
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    • 2005
  • The signal in wireless multi-path channel is affected by fading and ISI because of high data rate transmission, so the signal has the high error rate. The present modulation and demodulation method of DSRC system can not expect sufficient for providing data service over 1 Mbps, so the channel equalization and advanced modulation and demodulation methods are required. OFDM is generally known as an effective technique for high data rate transmission system, since it can prevent ISI by inserting a guard interval. However, a guard interval longer than channel delay spread has to be used in each OFDM symbol period, thus resulting a considerable loss in the efficiency of channel utilization Therefore the equalizer is necessary to cancel ISI to accommodate advanced ITS service with higher bit rate and longer channel delay spread condition In this paper, the channel equalizer for the OFDM -DSRC system was designed and its performance in a multi-path fading environment was evaluated with computer simulation.

Performance Analysis of Multiple Access Protocol for Maritime VHF Data Exchange System (VDES) (해상 초단파 대역 데이터 교환 시스템을 위한 다중 접속 방식의 성능 분석 연구)

  • Yun, Changho;Cho, A-Ra;Kim, Seung-Geun;Lim, Yong-Kon
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.18 no.12
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    • pp.2839-2846
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    • 2014
  • New VHF band for use in VDE is determined by WRC-12 due to the overload of AIS VDL, and the system characteristics of the VDE is recommended as ITU-R M. 1842-1. CS-TDMA, a multiple access method of AIS class B, is recommended as that of the VDE. It is inefficient for CS-TDMA just applying the report interval used in AIS class B to transmit high speed data with higher payload in the aspect of efficiency. In this paper, a simulation is executed in order to determine adequate report interval according to the number of active ships that affects directly network traffic. To this end, the performance of CS-TDMA, which includes the number of received packets, reception success rate, channel utilization, and collision rate, is investigated via a simulation.

A Study on Five Levels of Security Risk Assessment Model Design for Ensuring the u-Healthcare Information System (u-헬스케어시스템의 정보보안 체계 확보를 위한 5단계 보안위험도 평가모델 설계)

  • Noh, Si Choon
    • Convergence Security Journal
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    • v.13 no.4
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    • pp.11-17
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    • 2013
  • All u-Health system has security vulnerabilities. This vulnerability locally(local) or network(network) is on the potential risk. Smart environment of health information technology, Ad-hoc networking, wireless communication environments, u-health are major factor to increase the security vulnerability. u-health care information systems user terminal domain interval, interval public network infrastructure, networking section, the intranet are divided into sections. Health information systems by separating domain specific reason to assess vulnerability vulnerability countermeasure for each domain are different. u-Healthcare System 5 layers of security risk assessment system for domain-specific security vulnerability diagnosis system designed to take the security measures are needed. If you use this proposed model that has been conducted so far vaguely USN-based health information network security vulnerabilities diagnostic measures can be done more systematically provide a model.

Computerized bone age estimation system based on China-05 standard

  • Yin, Chuangao;Zhang, Miao;Wang, Chang;Lin, Huihui;Li, Gengwu;Zhu, Lichun;Fei, Weimin;Wang, Xiaoyu
    • Advances in nano research
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    • v.12 no.2
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    • pp.197-212
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    • 2022
  • The purpose of this study is to develop an automatic software system for bone age evaluation and to evaluate its accuracy in testing and feasibility in clinical practice. 20394 left-hand radiographs of healthy children (2-18 years old) were collected from China Skeletal Development Survey data of 1998 and China Skeletal Development Survey data of 2005. Three experienced radiologists and China-05 standard maker jointly evaluate the stages of bone development and the reference bone age was determined by consensus. 1020 from 20394 radiographs were picked randomly as test set and the remaining 19374 radiographs as training set and validation set. Accuracy of the automatic software system for bone age assessment is evaluated in test set and two clinical test sets. Compared with the reference standard, the automatic software system based on RUS-CHN for bone age assessment has a 0.04 years old mean difference, ±0.40 years old in 95% confidence interval by single reading, a 85.6% percentage agreement of ratings, a 93.7% bone age accuracy rate, 0.17 years old of MAD, 0.29 years old of RMS; Compared with the reference standard, the automatic software system based on TW3-C RUS has a 0.04 years old mean difference, a ±0.38 years old in 95% confidence interval by single reading, a 90.9% percentage agreement of ratings, a 93.2% bone age accuracy rate, a 0.16 years of MAD, and a 0.28 years of RMS. Automatic software system, AI-China-05 showed reliably accuracy in bone age estimation and steady determination in different clinical test sets.

Design of Polynomial Interval Type-2 TSK FLS and Its Application to Nonlinear System (다항식 Interval Type-2 TSK FLS 설계와 비선형 시스템으로의 응용)

  • Kim, Gil-Sung;Oh, Sung-Kwun
    • Proceedings of the KIEE Conference
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    • 2008.04a
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    • pp.57-58
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    • 2008
  • Type-2 퍼지 집합은 언어의 불확실성을 다루기 위하여 고안된 Type-1 퍼지집합의 확장이다. TSK 퍼지 로직 시스템(TSK Fuzzy Logic Systems; TSK FLS)은 Mamdani FLS과 함께 가장 널리 사용되는 퍼지 로직 시스템 모델이다. 본 논문에서는 Type-2 퍼지 집합을 이용하여 전반부 멤버쉽 함수를 구성하고 후반부 다항식 함수를 상수와 1차식, 2차식으로 확장한 다항식 Type-2 TSK FLS 설계한다. 다항식 Type-2 TSK FLS의 파라미터를 동정하기 위해 Back-propagation 방법을 사용한다. 제안된 다항식 Type-2 TSK FLS을 노이즈 섞인 비선형 시스템의 모델링에 적용하여 그 성능을 비교 분석한다.

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Estimation and Demonstration Test Plan for Availability with Weibull Lifetime and Lognormal Repair Time (와이블 수명분포와 대수정규 수리시간분포 하에서 가용도의 추정과 실증시험계획)

  • Seo, Sun-Keun
    • Journal of Applied Reliability
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    • v.14 no.1
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    • pp.1-9
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    • 2014
  • One important measure of performance for a repairable system is steady-state availability. In this paper, a method to estimate and establish confidence interval for the steady-state availability under Weibull lifetime and lognormal repair time distributions is proposed. Also, bias and mean squared error of a point estimator for an availability are investigated. In addition, a procedure to derive the sample size and critical value for availability demonstration test is presented and illustrated with a numerical example.