• Title/Summary/Keyword: time domain data

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Equivalent Circuit Model for Four Port Connector System (4포트 커넥터 시스템의 등가회로 변환에 관한 연구)

  • Shim, Min-Kyu;Kim, Jong-Min;Nah, Wan-Soo
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.56 no.6
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    • pp.1105-1110
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    • 2007
  • This paper describes an equivalent circuit modeling of 4-port connector system. A coupled transmission line was designed and fabricated, mimicking a 4-port connector system, and then S-parameters were measured using 4 port VNA (Vector Network Analyzer). The S-parameters from measurement and from Full-wave simulator coincided quite nice. By using these S parameters, an equivalent circuit parameters for a 4-port system was obtained. The time domain response from the equivalent circuit model matched to the signals, which was measured using TDR(Time Domain Reflectometry) meter. We were also convinced that there should be enough bandwidth to get a meaningful time domain result from Fourier inverse transformation of the S parameters. In addition, we applied the conversion algorithm to the 4-port connector system, which calculates the S-parameters of a 4 port system using the data from a 2-port VNA with the other ports open. Comparison of the two data, one from measurement and the other one from the conversion algorithm, was made in this manuscript.

Planform Curvature Effects on the Stability of Coupled Flow/Structure Vibration (면내 곡률이 천음속 및 초음속 유체/구조 연계 진동 안정성에 미치는 영향)

  • Kim, Jong-Yun;Kim, Dong-Hyun;Lee, In
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.12 no.11
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    • pp.864-872
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    • 2002
  • In this study, the effect of planform curvature on the stability of coupled flow/structure vibration is examined in transonic and supersonic flow regions. The aeroelastic analysis for the frequency and time domain is performed to obtain the flutter solution. The doublet lattice method(DLM) in subsonic flow is used to calculate unsteady aerodynamics in the frequency domain. For all speed range, the time domain nonlinear unsteady transonic small disturbance code has been incorporated into the coupled-time integration aeroelastic analysis (CTIA). Two curved wings with experimental data have been considered in this paper MSC/NASTRAN is used for natural free vibration analyses of wing models. Predicted flutter dynamic pressures and frequencies are compared with experimental data in subsonic and transonic flow regions.

A longitudinal analysis on trend of mathematical affective domain (수학 교과에 대한 정의적 특성의 종단적 추이 분석)

  • Kim, Hyunju;Kim, Won Kyung
    • The Mathematical Education
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    • v.55 no.4
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    • pp.447-465
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    • 2016
  • The purpose of this study is to analyze longitudinal trends of students' mathematical affective domain by use of the data mining method. For this purpose, we used the Korea education longitudinal study(KELS 2005) which was the survey data for students' achievement test, affective domain test, teachers' evaluation, and parents' evaluation from $7^{th}$ grader in the year of 2005 to $11^{th}$ grader in the year of 2010. Subjects of this study is a total of 5040 students who answered to the mathematical affective domain survey in KELS 2005. The result findings are as follows. First, students' affective domain had changed negatively as they went up to higher grade. Second, if students' affective domain had built at a certain level in $7^{th}$ grade, the level did not change easily until $11^{th}$ grade. Third, major factors of students' affective domain were shown to be self-efficacy, intrinsic motivation, efforts and patient, and time management.

The Improvement in Signal Integrity of FT-ICR MS (FT-ICR 질량분석기의 신호 충실성 향상)

  • Kim, Seung-Yong;Kim, Seok-Yoon;Kim, Hyun Sik
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.60 no.1
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    • pp.201-204
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    • 2011
  • For efficient noise reduction in a Fourier transform ion cyclotron resonance (FT-ICR) mass spectrum, a new algorithm was proposed. The suggested algorithm reduces white and electrical noise, and it improves signal-to-noise ratio. This algorithm has been optimized to reduce the noise more efficiently using the traces of signal level. The algorithm has been efficiently combined with derivative window to improve the resolution as well S/N. Time domain data was corrected for DC voltage interference. $t^n$ window was applied in time domain data to improved the resolution. However, $t^n$ window can improve the signal resolution, it will also increase the noise level in frequency domain. Therefore, newly developed noise reduction algorithm will be applied to make a balance between resolving power and S/N ratio for magnitude mode. The trace algorithm can determine the current data point with several data points (mean, past data, calculated past data). In the current calculations, we assumed data points with S/N ratio more than 3 were considered as signal data points. After the windowing and noise reduction, both resolution and signal-to-noise ratio were improved. This algorithm is applicable more efficiently to frequency dependent noise and large size data.

Prestack Reverse Time Migration for Seismic Reflection data in Block 5, Jeju Basin (제주분지 제 5광구 탄성파자료의 중합전 역시간 구조보정)

  • Ko, Chin-Surk;Jang, Seong-Hyung
    • Economic and Environmental Geology
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    • v.43 no.4
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    • pp.349-358
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    • 2010
  • For imaging complex subsurface structures such as salt dome, faults, thrust belt, and folds, seismic prestack reverse-time migration in depth domain is widely used, which is performed by the cross-correlation of shot-domain wavefield extrapolation with receiver-domain wavefield extrapolation. We apply the prestack reverse-time migration, which had been developed at KIGAM, to the seismic field data set of Block 5 in Jeju basin of Korea continental shelf in order to improve subsurface syncline stratigraphy image of the deep structures under the shot point 8km at the surface. We performed basic data processing for improving S/N ratio in the shot gathers, and constructed a velocity model from stack velocity which was calculated by the iterative velocity spectrum. The syncline structure of the stack image appears as disconnected interfaces due to the diffractions, but the result of the prestack migration shows that the syncline image is improved as seismic energy is concentrated on the geological interfaces.

Comparison in Elastic Wave Propagation Velocity Evaluation Methods (탄성파의 매질 내 이동속도 산정방법 비교)

  • Kim, Taesik
    • Journal of the Korean GEO-environmental Society
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    • v.15 no.5
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    • pp.31-37
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    • 2014
  • In situ investigations and laboratory tests using elastic wave have become popular in geotechnical and geoenvironmental engineering. Propagation velocity of elastic wave is the key index to evaluate the ground characteristics. To evaluate this, various methods were used in both time domain and frequency domain. In time domain, the travel time can be found from the two points that have the same phase such as peaks or first rises. Cross-correlation can also be used in time domain by evaluating the time shift amount that makes the product of signals of input and received waveforms maximum. In frequency domain, wave propagation velocity can be evaluated by computing the phase differences between the source and received waves. In this study, wave propagation velocity evaluated by the methods listed above were compared. Bender element tests were conducted on the specimens cut from the undisturbed hand-cut block samples obtained from Block 37 excavation site in Chicago, IL, US. The evaluation methods in time domain provides relatively wide range of wave propagation velocities due to the noise in signals and the sampling frequency of data logger. Frequency domain approach provides relatively accurate wave propagation velocities and is irrelevant to the sampling frequency of data logger.

Estimation Method of Cable Fault Location in Rocket Motors Using M-sequence Signals (M시퀀스 신호를 이용한 로켓 추진기관 케이블 결함 위치 추정 기법)

  • Son, Ji-Hong
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.21 no.5
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    • pp.84-92
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    • 2020
  • This paper describes the estimation method of cable fault location in rocket motors using M-sequence (Maximal Length Sequence). In order to estimate the location of a cable fault, three methods have been usually used: TDR (Time Domain Reflectometry), FDR (Frequency Domain Reflectometry), and TFDR (Time-Frequency Domain Reflectometry). However, these methods suffer the disadvantage of requiring users to be close to a test field, which is dangerous. The estimation method of cable fault location using M-sequence is proposed to solve this problem. The proposed method can make use of DAS (Data Acquisition System). The experiments were three cases: damaged, open, and short. The RG-58 coaxial cable was used in the experiments. As a result, the proposed method has better performance than that of conventional methods such as TDR and TFDR.

Domain Adaptive Fruit Detection Method based on a Vision-Language Model for Harvest Automation (작물 수확 자동화를 위한 시각 언어 모델 기반의 환경적응형 과수 검출 기술)

  • Changwoo Nam;Jimin Song;Yongsik Jin;Sang Jun Lee
    • IEMEK Journal of Embedded Systems and Applications
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    • v.19 no.2
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    • pp.73-81
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    • 2024
  • Recently, mobile manipulators have been utilized in agriculture industry for weed removal and harvest automation. This paper proposes a domain adaptive fruit detection method for harvest automation, by utilizing OWL-ViT model which is an open-vocabulary object detection model. The vision-language model can detect objects based on text prompt, and therefore, it can be extended to detect objects of undefined categories. In the development of deep learning models for real-world problems, constructing a large-scale labeled dataset is a time-consuming task and heavily relies on human effort. To reduce the labor-intensive workload, we utilized a large-scale public dataset as a source domain data and employed a domain adaptation method. Adversarial learning was conducted between a domain discriminator and feature extractor to reduce the gap between the distribution of feature vectors from the source domain and our target domain data. We collected a target domain dataset in a real-like environment and conducted experiments to demonstrate the effectiveness of the proposed method. In experiments, the domain adaptation method improved the AP50 metric from 38.88% to 78.59% for detecting objects within the range of 2m, and we achieved 81.7% of manipulation success rate.

Adolescents' online and offline socializing and delinquent behaviors: Cross-domain influences (청소년의 온라인과 오프라인 교우활동과 비행행동 간의 상호영향 분석)

  • Kim, Hyoseon;Moon, Ui Jeong;Shim, Hee Sub
    • Korean Journal of Family Welfare
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    • v.23 no.4
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    • pp.575-593
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    • 2018
  • Online and offline are not separate worlds, especially for adolescents. Many friends in offline settings originally met each other online, but cross-domain influences have rarely been examined. This study aims to examine how much time adolescents spend with peers in online and offline settings, and how time spent with peers influences their online and offline delinquent behaviors during their middle school years. This study used data from the Korean Children & Youth Panel Survey (KCYPS). We focused on students for whom information was available from all three years of middle school. We used a cross-lagged panel model to examine the bi-directional effect of online and offline behaviors over time. Results show that more time spent with peers offline was associated with more offline delinquency, and more time spent with peers online was associated with more online delinquency. Cross-domain influences were also found: more time with peers offline increased online delinquency, and vice versa. However, this adverse cross-domain influence was observed only for male adolescents, not for female adolescents. Implications for intervention programs are discussed for male and female adolescents.

Mass estimation using time-frequency analysis (시간-주파수 기법을 이용한 금속파편 질량 추정)

  • Choi, Young-Chul;Park, Jin-Ho;Yoon, Doo-Byung;Park, Keun-Bae
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2006.05a
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    • pp.1129-1134
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    • 2006
  • Mass estimation was derived as functions of acceleration magnitude and primary frequency. The conventional method of mass estimation used frequency data directly in the frequency domain. The signals that can be obtained sensor contained noise as well as impact signal. Therefore, how well we can detect the frequency data in noise directly determines the quality of mass estimation. To find exact frequency data, we used time-frequency analysis. The time frequency method are expected to be more useful than the conventional frequency domain analyses for the mass estimation problem on a plate type structure. Also it has been concluded that the smoothed WVD can give more reliable means than the other methodologies for the mass estimation in a noisy environment.

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