• Smart Structures and Systems
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• 제23권6호
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• pp.641-651
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• 2019

The stochastic stability control of the parameter-excited vibration of an inclined stay cable with multiple modes coupling under random and periodic combined support disturbances is studied by using the direct eigenvalue analysis approach based on the response moment stability, Floquet theorem, Fourier series and matrix eigenvalue analysis. The differential equation with time-varying parameters for the transverse vibration of the inclined cable with control under random and deterministic support disturbances is derived and converted into the randomly and deterministically parameter-excited multi-degree-of-freedom vibration equations. As the stochastic stability of the parameter-excited vibration is mainly determined by the characteristics of perturbation moment, the differential equation with only deterministic parameters for the perturbation second moment is derived based on the $It{\hat{o}}$ stochastic differential rule. The stochastically and deterministically parameter-excited vibration stability is then determined by the deterministic parameter-varying response moment stability. Based on the Floquet theorem, expanding the periodic parameters of the perturbation moment equation and the periodic component of the characteristic perturbation moment expression into the Fourier series yields the eigenvalue equation which determines the perturbation moment behavior. Thus the stochastic stability of the parameter-excited cable vibration under the random and periodic combined support disturbances is determined directly by the matrix eigenvalues. The direct eigenvalue analysis approach is applicable to the stochastic stability of the control cable with multiple modes coupling under various periodic and/or random support disturbances. Numerical results illustrate that the multiple cable modes need to be considered for the stochastic stability of the parameter-excited cable vibration under the random and periodic support disturbances, and the increase of the control damping rather than control stiffness can greatly enhance the stochastic stability of the parameter-excited cable vibration including the frequency width increase of the periodic disturbance and the critical value increase of the random disturbance amplitude.

• Nuclear Engineering and Technology
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• 제52권7호
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• pp.1532-1536
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• 2020

For ensuring nuclear safeguards, we report the analytical signal-detection performance of thermal ionization mass spectrometry (TIMS) with continuous heating for the measurement of isotopic ratios in samples containing ultra-trace amounts of uranium. As methods for detecting uranium signals, peak-jumping mode using a single detector and static mode using multiple detectors were examined with U100 (10% ²³⁵U-enriched) uranium standard samples in the femtogram-to-picogram range. Uranium isotope ratios, n(²³⁵U)/n(²³⁸U), were measured down to levels of 1 fg and 3 fg in static and peak-jumping modes, respectively, while n(²³⁴U)/n(²³⁸U) and n(²³⁶U)/n(²³⁸U) values were measured down to levels of 100 fg in both modes. In addition, the dependency of the ²³⁸U signal intensity on sample quantity exhibited similar tendencies in both modes. The precisions of the isotope ratios obtained in the static mode over all sample ranges used in this study were overall slightly higher than those obtained in peak-jumping mode. These results indicate that isotope ratio measurements by TIMS with continuous heating are almost independent of the detection method, i.e., peak-jumping mode or static mode, which is characteristic of isotope-ratio measurements using the TIMS method with continuous heating. TIMS with continuous heating is advantageous as it exhibits the properties of multiple detectors within a single detector, and is expected to be used in various fields in addition to ensuring nuclear safeguards.

• 한국지반공학회지:지반
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• 제4권2호
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• pp.15-24
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• 1988

확정론적 방법으로 안정조건을 만족하는 T형옹벽을 대상으로 지지력, 활동, 전도의 단일파괴류 형에 대해 설계변수를 통계적 독립이고 정규분포로 가정하여 AFOSM 방법으로 신뢰도 해석을하였다. 이를 바탕으로 각 파양모드 사이의 상관성을 고려한 구조물 전체적인 신뢰도는 신뢰지수로 2.05 이었다. 그러므로, 확정론적 설계법에 의해 안전상태로 판단된다 할지라도 신뢰도개념으로는 일반적인 목표신뢰지수(Target reliability index) 3보다 훨씬 낮기 때문에 안정상태로 판단하기는 곤란하다.

• Journal of Communications and Networks
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• 제11권4호
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• pp.406-415
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• 2009

In this work, we consider performance modeling of a wireless sensor network with a time division multiple access (TDMA) media access protocol with slot reuse. It is assumed that all the nodes are peers of each other and they have two modes of operation, active and sleep modes. We model the sensor network as a Jackson network with unreliable nodes with on and off states. Active and sleep modes of sensor nodes are modeled with on and off states of unreliable nodes. We determine the joint distribution of the sensor node queue lengths in the network. From this result, we derive the probability distribution of the number of active nodes and blocking probability of node activation. Then, we present the mean packet delay, average sleep period of a node and the network throughput. We present numerical results as well as simulation results to verify the analysis. Finally, we discuss how the derived results may be used in the design of sensor networks.

• Structural Engineering and Mechanics
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• 제15권3호
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• pp.299-314
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• 2003

This investigation presents an efficient method for identifying modal characteristics from the measured displacement, velocity and acceleration signals of multiple channels on structural systems. A Vector Backward Auto-Regressive model (VBAR) that describes the relationship between the output information in different time steps is used to establish a backward state equation. Generally, the accuracy of the identified dynamic characteristics can be improved by increasing the order of the Auto-Regressive model (AR) in cases of measurement of data under noisy circumstances. However, a higher-order AR model also induces more numerical modes, only some of which are the system modes. The proposed VBAR model provides a clear characteristic boundary to separate the system modes from the spurious modes. A numerical example of a lumped-mass model with three DOFs was established to verify the applicability and effectiveness of the proposed method. Finally, an offshore platform model was experimentally employed as an application case to confirm the proposed VBAR method can be applied to real-world structures.

• 전자공학회논문지A
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• 제33A권5호
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• pp.65-74
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• 1996

in this paper, the propagation characteristics of the dominant modes in multiple coupled microstrip lines on a magnetized ferrite substrate are analyzed. The propagation constants and characteristic impedances are calculated by using the spectral domain method. With the numerical results, multi-port impedance parameters as well as scattering parameters are derived from nonreciprocal transmission line equations which are consistent with conventional transmission line theory. In additon, the numerical resutls of nonreciprocal characteristics for various values of structural, material parameters, and external magnetic fields are also presented.

• 한국자기공명학회논문지
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• 제22권4호
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• pp.125-131
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• 2018

Chemical shift perturbation (CSP) is a simple NMR technique for studying binding of a protein to various ligands. CSP is the only technique that can directly provide both a value for the dissociation constant and a binding site from the same set of measurements. To accurately analyze the CSP data, the exact binding mode such as multiple binding, should be carefully considered. In this review, we analyzed systematically the CSP data with multiple modes. This analysis might provide insight into the mechanism on how proteins selectively recognize their target ligands to achieve the biological function.

• 한국멀티미디어학회논문지
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• 제17권2호
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• pp.143-151
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• 2014

악천후로 인하여 화질이 저하된 영상은 사물의 경계에 해당하는 에지 부분이 흐려진다. 본 논문에서는 에지를 최대한으로 선명하게 하여 영상의 시인성을 향상 시키는 화질 개선 방법을 제안한다. 우선 영상의 밝기 필드에서 극점들을 찾아 에지 후보 영역으로 선택하고, 선택된 에지의 측면에 있는 화소들의 밝기로 히스토그램을 형성한다. 형성된 히스토그램의 극소점을 기반으로 히스토그램을 다수의 모드로 분해한다. 모드가 구해지면, 영상 필드에서 에지에 의하여 연결된 모드들을 구하고, 연결된 모드들의 연결 고리를 구한다. 최종적으로 가장 긴 연결 고리를 형성하는 모드간의 간격을 최대한으로 벌린다. 이 때 최소 밝기 모드와 최대 밝기 모드는 화소 밝기 범위 이내에 있어야 한다. 이와 같이 모드의 간격을 벌림으로써 에지를 선명하게 하고 영상의 시인성을 향상한다. 본 논문에서 제안한 방법은 적은 연산량으로 기존의 방법만큼 좋은 성능으로 화질을 개선함을 보여준다.

• 한국안전학회지
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• 제19권1호
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• pp.23-30
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• 2004

Modern production systems are very complex by request of automation, and failure modes that occur in thisautomatic system are very various and complex. The efficient fault diagnosis for these complex systems is essential for productivity loss prevention and cost saving. Traditional fault diagnostic system which perforns sequential fault diagnosis can cause catastrophic failure during diagnosis when fault propagation is very fast. This paper describes the Real-time Intelligent Multiple Fault Diagnosis System (RIMFDS). RIMFDS assesses current machine condition by using sensor signals. This system deals with multiple fault diagnosis, comprising of two main parts. One is a personal computer for remote signal generation and transmission and the other is a host system for multiple fault diagnosis. The signal generator generates various faulty signals and image information and sends them to the host. The host has various modules and agents for efficient multiple fault diagnosis. A SUN workstation is used as a host for multiple fault modules and agents for efficient multiple fault diagnosis. A SUN workstation is used as a host for multiple fault diagnosis and graphic representation of the results. RIMFDS diagnoses multiple faults with fast fault propagation and complex physical phenomenon. The new system based on multiprocessing diagnoses by using Hierarchical Artificial Neural Network (HANN).

• 한국초전도학회:학술대회논문집
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• 한국초전도학회 2006년도 High Temperature Superconductivity Vol.XVI
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• pp.47-47
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• 2006