• 제목/요약/키워드: Envelope Analysis

검색결과 446건 처리시간 0.022초

음장의 공간 복소 포락: 정의와 특성 (Spatial Complex Envelope of Acoustic Field : Its Definition and Characteristics)

  • 박춘수;김양한
    • 한국소음진동공학회논문집
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    • 제17권8호
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    • pp.693-700
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    • 2007
  • We can predict spatial acoustic pressure distribution on the plane of interest by using acoustic holography. However, the information embedded in the distribution plot is usually much more than what we need: for example, source locations and their overall propagation pattern. One possible candidate to solve the problem is complex envelope analysis. Complex envelope analysis extracts slowly-varying envelope signal from a band signal. We have attempted to extend this method to space domain so that we can have spatial information that we need. We have to modulate two dimensional data for obtaining spatial envelope. Although spatial modulation basically follows the same concept that is used in time domain, the algorithm for the spatial modulation turns out to be different from temporal modulation. We briefly describe temporal complex envelope analysis and extend it to spatial envelope of 2-D acoustic field by introducing geometric transformation. In the end, the results of applying the spatial envelope to the holography are envisaged and verified.

Percentile Envelope and Its Characteristic of Error Distribution for Supernormality

  • 이제영;이성원
    • Journal of the Korean Data and Information Science Society
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    • 제12권2호
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    • pp.35-45
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    • 2001
  • We introduce a new percentile envelope for diagnosing supernormality in regression analysis. Furthermore, we compare this percentile envelope, which is much simpler and easier, with Atkinson's and Flack and Flores' envelopes. Using percentile envelope, we investigate characteristics of normal probability plots with envelope for error distributions when supernormality is occurred. We give cautions that test result for normality assumption of errors can be reached the wrong conclusion by supernormality.

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Envelope ADI-FDTD의 수치적 특성에 관한 연구 (A Study of the Numerical Characteristics of the Envelope ADI-FDTD)

  • 주세훈;정경영;김형훈;김형동
    • 한국전자파학회논문지
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    • 제14권6호
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    • pp.584-590
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    • 2003
  • 본 논문에서는 최근에 개발된 Envelope ADI-FDTD의 수치적 특성에 대하여 고찰하였다. 수치 실험을 통하여 Envelope ADI-FDTD가 시간간격에 상관없이 무조건 안정하고, 신호의 포락선을 해석함으로써 기존의 ADI-FDTD보다 더 좋은 분산특성을 얻을 수 있음을 보였다. 이러한 특성은 특별한 경우에서는 Nyquist 극한값까지 시간간격을 키울 수 있는 가능성을 제공한다 수치결과를 통해서 Envelope ADI-FDTD가 단일주파수 또는 대역이 제한된 시스템의 해석에 있어 유용하게 사용될 수 있음을 확인하였다.

포락선 분석을 이용한 산업용 기어박스의 결함 검출 (Faults Detection of Industrial Gearbox using an Envelope Analysis)

  • 박영준;이근호;이재정
    • Journal of Biosystems Engineering
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    • 제34권2호
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    • pp.82-88
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    • 2009
  • This study was conducted to detect faults in a gearbox comprised of gears, bearings and shafts. The envelope analysis was used as a method of detection, which could detect breakage and pitting of gears and bearings, and misalignment of shafts effectively. Vibration measured at the increaser was analyzed to characterize the faults. When the increaser has a defect, peaks with a constant period appear in the time history of vibration and its harmonic components also in the envelope spectrum. The envelope analysis showed that a crack in the stepped output shaft caused the increaser to generate the abnormal peaks.

우리나라 우편 봉투 영상에서의 주소 영역 추추을 위한 지식 기반 시스템 (A Knowledge-Based System for Address Block Location on Korean Envelope Images)

  • 김기철;이성환
    • 전자공학회논문지B
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    • 제31B권8호
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    • pp.137-147
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    • 1994
  • In this paper,we propose a knowledge-based system for locating Destination Address Block(DAB) by analyzing the structure of Korean envelope images. In the proposed system the preprocessing steps such as adaptive binarization connected component extraction and deskewing are carried out first for the effective structure analysis of the envelope image. Then DAB containing address name and zipcode parts of the input envelope image is extracted by an iterative procedure based on the knowledge acquired from the statistical feature analysis of the various envelope images. Most of the system for slocating address blocks on envelopes have extracted DAB by segmenting an envelope image into several candidate blocks followed by selecting one among the candidate blocks. Because it is very difficult to segment a Korean envelope image into several blocks due to the specific writing habits that the addresses on the envelope are written in close proximity to each other the proposed iterative procedure determines DAB by splitting or merging the connected components and verifies the determined DAB without segmentation and selection. Experiments with a great number of the live envelopes provided from Seoul Mail Center in Koorea were carried out. The results reveal that the proposed system is very effective for address block location on Korean envelopes.

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Constant Envelope Enhanced FQPSK and Its Performance Analysis

  • Xie, Zhidong;Zhang, Gengxin;Bian, Dongming
    • Journal of Communications and Networks
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    • 제13권5호
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    • pp.442-448
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    • 2011
  • It's a challenging task to design a high performance modulation for satellite and space communications due to the limited power and bandwidth resource. Constant envelope modulation is an attractive scheme to be used in such cases for their needlessness of input power back-off about 2~3 dB for avoidance of nonlinear distortion induced by high power amplifier. The envelope of Feher quadrature phase shift keying (FQPSK) has a least fluctuation of 0.18 dB (quasi constant envelope) and can be further improved. This paper improves FQPSK by defining a set of new waveform functions, which changes FQPSK to be a strictly constant envelope modulation. The performance of the FQPSK adopting new waveform is justified by analysis and simulation. The study results show that the novel FQPSK is immune to the impact of HPA and outperforms conventional FQPSK on bit error rate (BER) performance. The BER performance of this novel modulation is better than that of FQPSK by more than 0.5 dB at least and 2 dB at most.

민감도 분석을 통한 종합병원 병동부의 에너지 절감 외피 설계요소 도출 (A Study on Envelope Design Variables for Energy Conservation of General Hospital Ward Area by Sensitivity Analysis)

  • 오지현;권순정;김선숙
    • 의료ㆍ복지 건축 : 한국의료복지건축학회 논문집
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    • 제23권1호
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    • pp.7-14
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    • 2017
  • Purpose: Since the large hospitals are one of the most intensive energy users among building types in Korea, it is important to investigate and apply appropriate energy conservation measures. There are many researches on energy conservation measures for HVAC system in hospitals, but only few useful guidelines for envelope design variables were existed. The building envelope is one of the important factors to building energy consumption and patients' comfort. The purpose of this study is to suggest the most influential envelope design variables for each end-use energy demand. Methods: 100 samples were generated by LHS(Latin Hypercube Sampling) method. After energy performance simulation, global sensitivity analysis was performed by the regression method. DesignBuilder, Simlab 2.2 and JEPlus were used in this process. Results: The most influencing variables are SHGC, SHGC and VT for heating, cooling, and lighting, respectively. However, the most influencing variable for total energy demand is WWR(Window to Wall Ratio). The analysis was conducted based on the coefficient of variance results. Implications: The six envelop design variables were ranked according to the end-use energy demand.

노후 학교건물의 창호 교체에 따른 부하분석 (Analysis of Heating and Cooling Load Profile According to the Window Retrofit in an Old School Building)

  • 이예지;김주욱;송두삼
    • 설비공학논문집
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    • 제29권9호
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    • pp.455-462
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    • 2017
  • The purpose of this study is to analyze heating and cooling load variation due to envelope retrofits in an old school building. In a previous study, envelope retrofit of an old school building resulted in annual energy consumption reduction. However, cooling energy consumption increased with the envelope retrofit. This is because of high internal heat generation rates in school buildings and internal heat cannot escape through windows or walls when the envelope's thermal performance improves. To clarify this assumption, thermal performance changes due to envelope retrofits were analyzed by simulation. Results revealed indoor temperature and inner window surface temperature increased with high insulation level of windows. Indoor heat loss through windows by conduction, convection and radiation decreased and resulted in an increase of cooling load in an old school building. From results of this study, energy saving impact of envelope retrofits in an old school building may not be significant because of high internal heat gain level in school buildings. In case of replacing windows in school buildings, local climate and internal heat gain level should be considered.

남부지역 주거건물의 외피단열변화에 따른 에너지소비량 예측 (Prediction of the Amount of Energy Consumption by Variation in Envelope Insulation on a Detached House in Southern Part of Korea)

  • 문진우;한승훈;오세규
    • 한국주거학회논문집
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    • 제22권1호
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    • pp.115-122
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    • 2011
  • This study aimed at quantifying the impact of envelope insulation on energy consumption for thermal controls in residential buildings in southern part of Korea. A series of parametric simulations for a range of R-values of walls, roof, floor, and windows were computationally conducted for a prototypical Korean detached house. Analysis revealed that the total amount of heat gain was larger than that of heat loss, while the amount of energy for cooling was smaller than that for heating due to the difference of system efficiency; the envelope heat transfer was more significant for the heat loss, thus, the increase of the envelope insulation was more effective to reduce heating load; and there were certain levels of envelope insulation after which the energy saving effect was not significant. These findings are expected to be a fundamental database for the decision of proper insulation level in Korean residential buildings.

웨이블릿변환이 접목된 포락처리를 이용한 저속 회전하는 구름요소베어링 결함 진단 (Low Speed Rolling Bearing Fault Detection Using AE Signal Analyzed By Envelop Analysis Added DWT)

  • 김병수;김원철;구동식;김재구;최병근
    • Journal of Advanced Marine Engineering and Technology
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    • 제33권5호
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    • pp.672-678
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    • 2009
  • Acoustic Emission (AE) technique is a non-destructive testing method and widely used for the early detection of faults in rotating machines in these days, because the sensitivity of AE transducers is higher than normal accelerometers. So it can detect low energy vibration signals. The faults in the rotating machines are generally occurred at bearings and gearboxes which are the principal parts of the machines. It was studied to detect the bearing faults by envelop analysis in several decade years. And the researches showed that AE had a possibility of the application in condition monitoring system(CMS) using the envelope analysis for the rolling bearing. And peak ratio (PR) was developed for expression of the bearing condition in condition monitoring system using AE. Noise level is needed to reduce to take exact PR value because the PR is calculated from total root mean square (RMS) and the harmonics peak levels of the defect frequencies of the bearing. Therefore, in this paper, the discrete wavelet transform (DWT) was added in the envelope analysis to reduce the noise level in the AE signals. And then, the PR was calculated and compared with general envelope analysis result and the result of envelope analysis added the DWT. In the experiment result about inner fault of bearing, defect frequency was difficult to find about only envelop analysis. But it's easy to find defect frequency after wavelet transform. Therefore, Envelop analysis added wavelet transform was useful method for early detection of default in signal process.