• Title/Summary/Keyword: ISI

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Comparative Study on the Technical Standards for the In-Service Inspection of Nuclear Power Plant Components in Several Countries (원전의 가동중검사 관련 각국의 기술기준 비교고찰)

  • Shin, Ho-Sang;Kim, Kyung-Jo;Jang, Chang-Heui;Kang, Suk-Chull
    • Journal of the Korean Society for Nondestructive Testing
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    • v.24 no.2
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    • pp.186-196
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    • 2004
  • In each country, the periodic ISI(In-Service Inspection) is required by the law to protect the public health and property from the potential accident of the nuclear facilities. To support the implementation of ISI program, the prescriptive ISI technical standards have been established. As the key parts of the ISI program, the non-destructive examination techniques are widely used to identify the degree of degradation of the pressure boundary components and welds. Recently, the risk informed-ISI program has been developed and implemented in several countries. Nonetheless, the existing ISI program which prescriptively decides the scope of inspection still has its own significance. In this article, the technical standards of ISI in leading countries like US, france, Canada, and Japan are reviewed and compared with the safety guide by IAEA. An outline to revise the domestic technical standards of ISI has been suggested.

An Adaptive Linear Channel Equalizer Using Asymmetric Transversal Filter (비대칭 필터 구조를 이용한 적응형 선형 채널 등화기)

  • Han, Jong-Young;Lim, Dong-Guk;Kim, Jae-Moung
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.30 no.9A
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    • pp.830-837
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    • 2005
  • ISI is caused by delay spread in the multipath channel environment. There are two kinds of channel equalizer: Linear and Non-Linear type according to the structures. In this paper, we propose an improved adaptive linear equalizer to mitigate ISI. The proposed adaptive equalizer is constructed by using asymmetrical Dsmvenu filter based on USE sub-optimal receiver. Asymmetrical structure of the transversal filter is realized by moving the main tap position from center to side. If this structure is used, we can divide ISI to precusor and postcusor. As a result the proposed equalizer has a larger extended compensation range than conventional adaptive linear equalizer. In computer simulation, we compare the bit error rate performance of the proposed linear equalizer with the conventional one on the S-V channel which is modeled for WB systems.

4-Level Balanced Modulation Code for the Mitigation of Two-Dimensional Intersymbol Interference in Holographic Data-Storage Systems (홀로그래픽 데이터 저장장치에서 2차원 심볼 간 간섭을 완화하기 위한 4-레벨 균형 변조부호)

  • Park, Keunhwan;Lee, Jaejin
    • Journal of the Institute of Electronics and Information Engineers
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    • v.53 no.9
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    • pp.12-17
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    • 2016
  • In the holographic data storage system (HDSS), the data regarding the volume of a storage medium are recorded and read by the page, and the transmission rate and storage capacity can be increased because of two-dimensional, page-oriented data processing; furthermore, the multi-level HDSS can store more than one bit per pixel. For this same reason, however, and unlike conventional data-storage systems, the HDSS is hampered by two-dimensional (2D) intersymbol interference (ISI) and interpage interference (IPI). Progress regarding the published papers on 2D ISI, which is more severe in the multi-level HDSS, continues; however, mitigation of both 2D ISI and IPI in terms of the multi-level HDSS has not yet been studied. In this paper, we therefore propose a 4-level balanced-modulation code that simultaneously mitigates 2D ISI and IPI.

Performance of Iterative Equalizer for ISI channel

  • Nguyen, Quoc Kien;Jeon, Taehyun
    • International journal of advanced smart convergence
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    • v.9 no.3
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    • pp.141-144
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    • 2020
  • Iterative decision feedback equalizer (IDFE) is a recursive equalization technique that can help to achieve an additional performance gain for the system by combining iterative channel decoding and interference cancellation. In a single carrier-based system, the intersymbol interference (ISI) is a critical problem that must be resolved since it causes frequency selective fading. Based on the idea of sharing the estimated information in the process of iteration, IDFE is considered as an efficient solution to improve the robustness of the system performance on the ISI channel. In this paper, the IDFE is applied on single carrier FDMA (SC-FDMA) system to evaluate the performance under ISI channel. The simulation results illustrate that IDFE helps to improve the performance of the SC-FDMA system, especially with long delay spread channels.

Path Tracking Control Based on RMAC in Horizontal Plane for a Torpedo-Shape AUV, ISiMi (RMAC를 적용한 어뢰형 무인잠수정(ISiMi)의 수평면 경로추종 제어)

  • Kim, Young-Shik;Lee, Ji-Hong;Kim, Jin-Ha;Jun, Bong-Huan;Lee, Pan-Mook
    • Journal of Ocean Engineering and Technology
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    • v.23 no.6
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    • pp.146-155
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    • 2009
  • This paper considers the path tracking problem in a horizontal plane for underactuated (or non-holonomic) autonomous underwater vehicles (AUVs). Underwater mapping has been an important mission for AUVs. Recently, underwater docking has also become a main research field of AUVs. These kinds of missions basically require accurate attitude and trajectory control performance. However, the non-holonomic problem should be solved to achieve accurate path tracking for the torpedo-type of AUVs. In this paper, resolved motion and acceleration control (RMAC) is considered as a path tracking controller for an underactuated torpedo-shaped AUV, ISiMi. A set of numerical simulations is carried out to illustrate the effectiveness of the proposed RMAC scheme, and experimental data with ISiMi100 and discussions are presented.

ISI NDE Total Support System for Korean Nuclear Power Plants (원전 가동중검사 종합지원체계)

  • Jeong, Yi-Hwan Peter
    • Journal of the Korean Society for Nondestructive Testing
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    • v.18 no.4
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    • pp.321-329
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    • 1998
  • Structural integrity of nuclear components is important for a safe operation of nuclear power plants. Therefore, nuclear power plants require to perform reliable, periodic inservice inspections. Korea Electric Power Company(KEPCO) operates the entire Korean nuclear power plants. Since nuclear power plant safety and the associated inservice inspection(ISI) are under the plant owner's responsibility, Korea Electric Power Research Institute(KEPRI), the R&D division of KEPCO, has established the ISI NDE Total Support system(TSS) for an efficient performance of ISI tasks, and initiated both key ISI NDE technology development program and traing & qualification system development program for an independent ISI operation. This paper describes details of these programs.

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Application of Risk-Informed Inservice Inspection for Piping in Nuclear Power Plants (리스크 정보를 활용한 배관 가동중검사 적용)

  • Jin, Young Bok;Jin, Seuk Hong;Moon, Yong Sig
    • Transactions of the Korean Society of Pressure Vessels and Piping
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    • v.7 no.4
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    • pp.31-37
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    • 2011
  • Pressurized Water Reactor Owners Group(PWROG) proposed and applied a risk-informed inservice inspection(RI-ISI) program to alternate existing ASME Section XI periodic inspections. The RI-ISI programs enhance overall safety by focusing inspections of piping at high safety significant(HSS) and locations where failure mechanisms are likely to be present, and by improving the effectiveness on inspection of components because the examination methods are based on the postulated failure mode and the configuration of the piping structural element. The RI-ISI programs can reduce NDE, man-rem exposure, costs of engineering analysis, outage duration and chance of complicating plant operations etc. RI-ISI methods of piping inservice inspection were applied on 3 units(KSNP : Korea Standard Nuclear Power Plant) and are scheduled to apply on the other units. In this paper, we compared and showed the results of the 2 units and we concluded that the RI-ISI application could enhance and maintain plant safety and give unquantifiable benefits.

Robust Decision Feedback Equalizer for OFDM System under Severe ISI Channel

  • Su, Xin;Hui, Bing;Chang, KyungHi
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • v.8 no.6
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    • pp.1914-1925
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    • 2014
  • Inter-symbol interference (ISI) problem is inevitable when the guard interval (GI) is shorter than the delay spread (DS) for an orthogonal frequency division multiplexing (OFDM) system. Iterative techniques have been proposed to overcome such a problem. However, most of existing algorithms are not efficient for an OFDM system with a small GI working under the channel with a large DS. Especially in the case of the DS spans a longer time than the half of the OFDM symbol duration. On the other hand, conventional algorithms, which can reduce the effects of the severe ISI, often employ several impractical assumptions to support the conclusions. In this paper, we present a robust decision feedback equalizer (DFE) for the OFDM system to overcome the severe ISI problem. The proposed DFE removes the ISI in a same manner as the residual inter-symbol interference cancellation (RISIC) algorithm. However, the inter-carrier interference (ICI) is reduced via cyclicity removal instead of the cyclicity restoration used in the conventional algorithms. The link-level simulation (LLS) results indicate that our proposed DFE scheme can dramatically improve the BER performance when the DS spans longer than the half of ODFM symbol duration.

A study on the effect of leading sound and following sound on sound localization (선행음 및 후속음이 음원의 방향지각에 미치는 영향에 관한 연구)

  • Lee, Chai-Bong
    • Journal of the Institute of Convergence Signal Processing
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    • v.16 no.2
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    • pp.40-43
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    • 2015
  • In this paper, the effects of the leading and the following sounds with single frequency on sound localization are investigated. The sounds with different levels and ISIs(Inter Stimuli Intervals) were used. The width of test sound is 2ms, and those of the leading and the following sounds are 10ms. 1 kHz of the test sound is utilized. The arrival time difference in the subject's ears is set to be 0.5ms. The four kinds of level differences used for one ISI are 0, -10, -15, and -20dB interval. The leading sound is found to have more effect on sound localization than the following sound is. The effect of the leading sound is also found to be dependent on the value of ISI. When the value of the ISI is small, different effects affecting the sound localization are observed.

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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