• Title/Summary/Keyword: Time-Domain Analysis

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Development of Buried Type TDR Module for Leak Detection from Buried Pipe (매설관 주변부 누수 탐지를 위한 매설형 TDR 모듈 개발)

  • Hong, Wontaek
    • Journal of the Korean GEO-environmental Society
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    • v.22 no.11
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    • pp.31-37
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    • 2021
  • To prevent accidents due to the cavities and loosened layers formed due to water leakage from the deteriorated buried pipes, evaluation of the changes in water contents around the buried pipes is required. As a method to evaluate the water contents of the soils, time domain reflectometry (TDR) system can be adopted. However, slender electrodes used in standard TDR probe may be damaged when buried in the ground. Thus, in this study, buried type TDR module was developed for the evaluation of the water contents with maintaining required shape of the electrodes in the ground. The TDR module is composed of three electrodes connected to the core conductor and outer conductor and a casing to prevent deformation and maintain alignment of the electrodes in the ground. For the verification of TDR waveforms measured using the TDR module, comparative analysis was conducted with the TDR waveforms measured using the standard TDR probe, and the relationship between the volumetric water content of the soils and the travel time of the guided electromagnetic wave was constructed. In addition, a model test was conducted to test the applicability of the buried type TDR module, and the experimental result shows that the TDR module clearly evaluates the changes in volumetric water contents due to the leakage from the modeled buried pipe. Therefore, the buried type TDR module may be effectively used for the health monitoring of the buried pipe and the evaluation of the water contents around the pipes buried in the urban pavements.

A Study on the Effects of Ambient Light on the Reflective PPG Measurement Device using Infrared (적외선을 사용한 반사형 PPG 측정 장치에서의 주변광의 영향에 대한 연구)

  • Namsub Kim
    • The Journal of Korea Institute of Information, Electronics, and Communication Technology
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    • v.16 no.6
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    • pp.406-412
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    • 2023
  • In this paper, we studied the effect of noise caused by ambient light on a reflective PPG measurement device using infrared light. Noise caused by ambient light was examined by dividing it into general situations and special situations. In the general situation, noise due to changes in time and ambient light sources was randomly observed, and in the special situation, a halogen lamp was used to observe the effect of noise variations. In the experiment, PPG signals were measured and data acquired in real-time depending on each situation, and the measured data was analyzed in the time domain and frequency domain. First, through a general situation experiments, it was visually observed that noise increases with the brightness of ambient light, and through frequency analysis, it was observed that the noise sources were white noise, power line noise, and internal noise of the circuit. Futhermore, using a halogen lamp, we experimented with the change in noise depending on the change in distance from the ambient light and calculated the SNR. As a result of the experiment, an SNR of 3.2 dB was shown at a distance of 50 cm with an irradiance of 278.3 W/m2. It was observed that normal measurement was difficult at SNRs below that, and an irradiance of 27.7 W/m2 was obtained. It showed a value of 18.2 dB at a distance of 2 m, and it was observed that normal PPG measurement was possible through a filter at values above that.

Mobile IP local pre-registration scheme for accommodating real-time data traffics in cdma2000 Networks (cdma2000 네트워크에서 실시간 데이터 트래픽을 수용하기 위한 Mobile IP 지역내 사전등록 기법)

  • 박민철;임재성
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.28 no.7A
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    • pp.493-502
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    • 2003
  • In this paper, to solve some problems of the Mobile IP and local registration strategy we propose a method that can effectively support real-time traffics sensitive to delay time and packet loss. The proposed method reduces the registration time after a Mobile Node's movement between networks by carrying out the pre-registration for the domain which it will move into the network information of the link layer of cdma2000 system, at the boundary cell's handoff zone. Through the cost analysis and simulation it is shown that the proposed scheme yield a better performance compared with the Mobile IP and local registration strategies in terms of packet loss for parameters; variation of the velocity of a Mobile Node, and a distance between the Mobile Node and home networks, etc.

A Quantitative Analysis of Nonlinearity Changes of 24 hour Heart Rate Variability of TOF Children Group and Normal Children Group (TOF 소아 집단과 정상 소아 집단의 24 시간 심박동수 변동량의 비선형성 변화에 대한 정량적 분석)

  • Lee, J.M.;Noh, J.I.;Park, K.S.
    • Proceedings of the KOSOMBE Conference
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    • v.1997 no.11
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    • pp.451-454
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    • 1997
  • It has been reported that sudden cardiac death and ventricular tachycardia occur after treatment of tetralogy of fallot(TOF). It is regarded that ventricular arrythmia is the main source or the sudden cardiac death, but it is not verified. It is likely that TOF has effect on the heart rate variability because of the ventricular arrythmia. We study how complex and periodic heart rate dynamics change in the normal children (n=13) and TOF children (n=13) throughout 24 hours. We recorded 24-hour holter ECG, and segmented each ECG data into 1 hour length. We analyze each HR time series, and quantify the overall complexity of each HR time series by its correlation dimension. We also calculate the power spectrum of HR, and obtain low-frequency component (0.03-0.15Hz) and high-frequency component (0.15-0.4Hz). We compare the results between normal and TOF groups throughout 24 hours. TOF group have lower correlation dimension ($4.055{\pm}0.4134$ vs. $4.9310{\pm}0.2054$, p<0.05) than the normal group, even though there are no significant differences in the low($0.9864{\pm}0.5598$ vs. $1.5560{\pm}0.8325$, p<0.05) and high($1.1168{\pm}0.1.1448$ vs. $0.9271{\pm}0.6528$, p<0.05) frequency components. It can be concluded that HR time series of TOF group are more regular than that of normal group, and that correlation dimension reveals a nonlinear characteristics of HR time series which is not determined in the frequency domain.

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A Design and Analysis of Improved Firefly Algorithm Based on the Heuristic (휴리스틱에 의하여 개선된 반딧불이 알고리즘의 설계와 분석)

  • Rhee, Hyun-Sook;Lee, Jung-Woo;Oh, Kyung-Whan
    • The KIPS Transactions:PartB
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    • v.18B no.1
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    • pp.39-44
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    • 2011
  • In this paper, we propose a method to improve the Firefly Algorithm(FA) introduced by Xin-She Yang, recently. We design and analyze the improved firefly algorithm based on the heuristic. We compare the FA with the Particle Swarm Optimization (PSO) which the problem domain is similar with the FA in terms of accuracy, algorithm convergence time, the motion of each particle. The compare experiments show that the accuracy of FA is not worse than PSO's, but the convergence time of FA is slower than PSO's. In this paper, we consider intuitive reasons of slow convergence time problem of FA, and propose the improved version of FA using a partial mutation heuristic based on the consideration. The experiments using benchmark functions show the accuracy and convergence time of the improved FA are better than them of PSO and original FA.

Latent topics-based product reputation mining (잠재 토픽 기반의 제품 평판 마이닝)

  • Park, Sang-Min;On, Byung-Won
    • Journal of Intelligence and Information Systems
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    • v.23 no.2
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    • pp.39-70
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    • 2017
  • Data-drive analytics techniques have been recently applied to public surveys. Instead of simply gathering survey results or expert opinions to research the preference for a recently launched product, enterprises need a way to collect and analyze various types of online data and then accurately figure out customer preferences. In the main concept of existing data-based survey methods, the sentiment lexicon for a particular domain is first constructed by domain experts who usually judge the positive, neutral, or negative meanings of the frequently used words from the collected text documents. In order to research the preference for a particular product, the existing approach collects (1) review posts, which are related to the product, from several product review web sites; (2) extracts sentences (or phrases) in the collection after the pre-processing step such as stemming and removal of stop words is performed; (3) classifies the polarity (either positive or negative sense) of each sentence (or phrase) based on the sentiment lexicon; and (4) estimates the positive and negative ratios of the product by dividing the total numbers of the positive and negative sentences (or phrases) by the total number of the sentences (or phrases) in the collection. Furthermore, the existing approach automatically finds important sentences (or phrases) including the positive and negative meaning to/against the product. As a motivated example, given a product like Sonata made by Hyundai Motors, customers often want to see the summary note including what positive points are in the 'car design' aspect as well as what negative points are in thesame aspect. They also want to gain more useful information regarding other aspects such as 'car quality', 'car performance', and 'car service.' Such an information will enable customers to make good choice when they attempt to purchase brand-new vehicles. In addition, automobile makers will be able to figure out the preference and positive/negative points for new models on market. In the near future, the weak points of the models will be improved by the sentiment analysis. For this, the existing approach computes the sentiment score of each sentence (or phrase) and then selects top-k sentences (or phrases) with the highest positive and negative scores. However, the existing approach has several shortcomings and is limited to apply to real applications. The main disadvantages of the existing approach is as follows: (1) The main aspects (e.g., car design, quality, performance, and service) to a product (e.g., Hyundai Sonata) are not considered. Through the sentiment analysis without considering aspects, as a result, the summary note including the positive and negative ratios of the product and top-k sentences (or phrases) with the highest sentiment scores in the entire corpus is just reported to customers and car makers. This approach is not enough and main aspects of the target product need to be considered in the sentiment analysis. (2) In general, since the same word has different meanings across different domains, the sentiment lexicon which is proper to each domain needs to be constructed. The efficient way to construct the sentiment lexicon per domain is required because the sentiment lexicon construction is labor intensive and time consuming. To address the above problems, in this article, we propose a novel product reputation mining algorithm that (1) extracts topics hidden in review documents written by customers; (2) mines main aspects based on the extracted topics; (3) measures the positive and negative ratios of the product using the aspects; and (4) presents the digest in which a few important sentences with the positive and negative meanings are listed in each aspect. Unlike the existing approach, using hidden topics makes experts construct the sentimental lexicon easily and quickly. Furthermore, reinforcing topic semantics, we can improve the accuracy of the product reputation mining algorithms more largely than that of the existing approach. In the experiments, we collected large review documents to the domestic vehicles such as K5, SM5, and Avante; measured the positive and negative ratios of the three cars; showed top-k positive and negative summaries per aspect; and conducted statistical analysis. Our experimental results clearly show the effectiveness of the proposed method, compared with the existing method.

A Bibliometric Analysis on LED Research (계량서지적 기법을 활용한 LED 핵심 주제영역의 연구 동향 분석)

  • Lee, Jae-Yun;Kim, Pan-Jun;Kang, Dae-Shin;Kim, Hee-Jung;Yu, So-Young;Lee, Woo-Hyoung
    • Journal of Information Management
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    • v.42 no.3
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    • pp.1-26
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    • 2011
  • The domain of LED is analyzed for describing the current status of Korea's R&D in the domain comparing with those of others quantitatively. Fourteen sub-domains of LED manufacturing technology are selected and the time span for analysis is ten-year: 2001-2010. Bibiliometric analysis is performed by the unit of publication, core researcher, institution and country. Strategical diagram is also produced with devised two indicators: NGI and NPI. As a result, Korea is competitive in the area of Chip Scale Package, but R&D supports in another promising areas, such as large-caliber sapphire wafer, are necessary. It is also revealed that research activities are expanded dominantly in academia, but practical technologies are developed in industrial circle. It is suggested that to support core corporate and to encourage industrial-academic collaboration is essential for systematical technology development and high achievement in prominent areas.

Integrated transcriptomic analysis on small yellow follicles reveals that sosondowah ankyrin repeat domain family member A inhibits chicken follicle selection

  • Zhong, Conghao;Liu, Zemin;Qiao, Xibo;Kang, Li;Sun, Yi;Jiang, Yunliang
    • Animal Bioscience
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    • v.34 no.8
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    • pp.1290-1302
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    • 2021
  • Objective: Follicle selection is an important process in chicken egg laying. Among several small yellow (SY) follicles, the one exhibiting the highest expression of follicle stimulation hormone receptor (FSHR) will be selected to become a hierarchal follicle. The role of lncRNA, miRNA and other non-coding RNA in chicken follicle selection is unclear. Methods: In this study, the whole transcriptome sequencing of SY follicles with different expression levels of FSHR in Jining Bairi hens was performed, and the expression of 30 randomly selected mRNAs, lncRNAs and miRNAs was validated by quantitative real-time polymerase chain reaction. Preliminary studies and bioinformatics analysis were performed on the selected mRNA, lncRNA, miRNA and their target genes. The effect of identified gene was examined in the granulosa cells of chicken follicles. Results: Integrated transcriptomic analysis on chicken SY follicles differing in FSHR expression revealed 467 differentially expressed mRNA genes, 134 differentially expressed lncRNA genes and 34 differentially expressed miRNA genes, and sosondowah ankyrin repeat domain family member A (SOWAHA) was the common target gene of three miRNAs and one lncRNA. SOWAHA was mainly expressed in small white (SW) and SY follicles and was affected by follicle stimulation hormone (FSH) treatment in the granulosa cells. Knockdown of SOWAHA inhibited the expression of Wnt family member 4 (Wnt4) and steroidogenic acute regulatory protein (StAR) in the granulosa cells of prehierarchal follicles, while stimulated Wnt4 in hierarchal follicles. Overexpression of SOWAHA increased the expression of Wnt4 in the granulosa cells of prehierarchal follicles, decreased that of StAR and cytochrome P450 family 11 subfamily A member 1 in the granulosa cells of hierarchal follicles and inhibited the proliferation of granulosa cells. Conclusion: Integrated analysis of chicken SY follicle transcriptomes identified SOWAHA as a network gene that is affected by FSH in granulosa cells of ovarian follicles. SOWAHA affected the expression of genes involved in chicken follicle selection and inhibited the proliferation of granulosa cells, suggesting an inhibitory role in chicken follicle selection.

Evaluation of Short and Long-Term Modal Parameters of a Cable-Stayed Bridge Based on Operational Modal Analysis (운용모드해석에 기반한 사장교의 장단기 동특성 평가)

  • Park, Jong-Chil
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.26 no.4
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    • pp.20-29
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    • 2022
  • The operational modal analysis (OMA) technique, which extracts the modal parameters of a structural system using ambient vibrations, has been actively developed as a field of structural health monitoring of cable-supported bridges. In this paper, the short and long-term modal parameters of a cable-stayed bridge were evaluated using the acceleration data obtained from the two ambient vibration tests (AVTs) and three years of continuous measurements. A total of 27 vertical modes and 1 lateral mode in the range 0.1 ~ 2.5 Hz were extracted from the high-resolution AVTs which were conducted in the 6th and 19th years after its completion. Existing OMA methods such as Peak-Picking (PP), Eigensystem Realization Algorithm with Data Correlation (ERADC), Frequency Domain Decomposition (FDD) and Time Domain Decomposition (TDD) were applied for modal parameters extraction, and it was confirmed that there was no significant difference between the applied methods. From the correlation analysis between long-term natural frequencies and environmental factors, it was confirmed that temperature change is the dominant factor influencing natural frequency fluctuations. It was revealed that the decreased natural frequencies of the bridge were not due to changes in structural performance and integrity, but to the environmental effects caused by the temperature difference between the two AVTs. In addition, when the TDD technique is applied, the accuracy of extracted mode shapes is improved by adding a proposed algorithm that normalizes the sequence so that the autocorrelations at zero lag equal 1.

Automated Finite Element Analyses for Structural Integrated Systems (통합 구조 시스템의 유한요소해석 자동화)

  • Chongyul Yoon
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.37 no.1
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    • pp.49-56
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    • 2024
  • An automated dynamic structural analysis module stands as a crucial element within a structural integrated mitigation system. This module must deliver prompt real-time responses to enable timely actions, such as evacuation or warnings, in response to the severity posed by the structural system. The finite element method, a widely adopted approximate structural analysis approach globally, owes its popularity in part to its user-friendly nature. However, the computational efficiency and accuracy of results depend on the user-provided finite element mesh, with the number of elements and their quality playing pivotal roles. This paper introduces a computationally efficient adaptive mesh generation scheme that optimally combines the h-method of node movement and the r-method of element division for mesh refinement. Adaptive mesh generation schemes automatically create finite element meshes, and in this case, representative strain values for a given mesh are employed for error estimates. When applied to dynamic problems analyzed in the time domain, meshes need to be modified at each time step, considering a few hundred or thousand steps. The algorithm's specifics are demonstrated through a standard cantilever beam example subjected to a concentrated load at the free end. Additionally, a portal frame example showcases the generation of various robust meshes. These examples illustrate the adaptive algorithm's capability to produce robust meshes, ensuring reasonable accuracy and efficient computing time. Moreover, the study highlights the potential for the scheme's effective application in complex structural dynamic problems, such as those subjected to seismic or erratic wind loads. It also emphasizes its suitability for general nonlinear analysis problems, establishing the versatility and reliability of the proposed adaptive mesh generation scheme.