• Smart Structures and Systems
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• 제19권3호
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• pp.259-268
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• 2017

System identification of structures is one of the important aspects of structural health monitoring. The accuracy and efficiency of identification results is affected severely by measurement noises, especially when the structure system is large, such as bridge structures, and when online system identification is required. In this paper, the least square estimation (LSE) method is used combined with the substructure approach for identifying structural parameters of a cable-stay bridge with large degree of freedoms online. Numerical analysis is carried out by first dividing the bridge structure into smaller substructures and then estimates the parameters of each substructure online using LSE method. Simulation results demonstrate that the proposed approach is capable of identifying structural parameters, however, the accuracy and efficiency of identification results depend highly on the noise sensitivities of loading region, loading pattern as well as element size.

• 한국지능시스템학회논문지
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• 제20권6호
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• pp.820-824
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• 2010

유전 알고리즘은 비선형 전역 최적화 문제 해결에 효과적이라고 알려져 있다. 그러나 해답의 신뢰성을 높이려면 많은 양의 계산이 필요하여 온라인 방식에는 적합하지 않다. 본 논문에서는 집단 피드백 유전 알고리즘을 사용한 온라인 비선형 시스템 식별기 구성을 제안한다. 제안된 시스템 식별기의 유용성은 모의실험을 통해 보인다.

• Nuclear Engineering and Technology
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• 제54권12호
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• pp.4751-4758
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• 2022

Two-phase flow may almost exist in every branch of the energy industry. For the corresponding engineering design, it is very essential and crucial to monitor flow patterns and their transitions accurately. With the high-speed development and success of deep learning based on convolutional neural network (CNN), the study of flow pattern identification recently almost focused on this methodology. Additionally, the photographing technique has attractive implementation features as well, since it is normally considerably less expensive than other techniques. The development of such a two-phase flow pattern online monitoring system is the objective of this work, which seldom studied before. The ongoing preliminary engineering design (including hardware and software) of the system are introduced. The flow pattern identification method based on CNNs and transfer learning was discussed in detail. Several potential CNN candidates such as ALexNet, VggNet16 and ResNets were introduced and compared with each other based on a flow pattern dataset. According to the results, ResNet50 is the most promising CNN network for the system owing to its high precision, fast classification and strong robustness. This work can be a reference for the online monitoring system design in the energy system.

• 정보관리학회지
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• 제41권1호
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• pp.133-162
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• 2024

디지털화가 급속히 진행됨에 따라, 온라인 자료의 식별 및 관리의 중요성이 대두되고 있다. 특히, 디지털 콘텐츠의 효율적인 유통 및 보존을 위한 체계적인 식별체계의 필요성이 증가하고 있다. 본 연구는 이러한 시대적 요구에 부응하여, 온라인 자료의 식별 및 관리를 위한 현행 식별체계의 실태를 조사하고, 이를 납본과 연계하여 보다 체계적인 관리 및 활용 방안을 모색하는 것을 목적으로 한다. 이를 위해 온라인 자료 식별체계와 발급실태를 조사하고 온라인 자료에 관련된 선행연구를 분석하였다. 분석결과를 기반으로 한 납본 연계방안은 다음과 같이 세 가지로 요약할 수 있다. 첫째, 납본의 우선순위 및 활용성을 위해 납본과 이용의 상호보완 강화, 납본의 우선순위 부여, 납본자료의 활용성 증대 전략이 요구된다. 둘째, 국제표준번호를 기반으로 한 납본 연계 방안으로서, ISBN과 UCI의 연계 납본, 국제표준자료번호와 납본 연계, 국제표준번호와 UCI의 메타데이터연계, UCI와 ICN의 연계 통합, 납본시스템 고도화를 위한 자동화 기술 도입 전략이 요구된다. 셋째, 위에서 제안한 전략들이 그 효과적으로 작용하기 위해서는 정책적인 지원도 같이 이루어져야 할 것이다. 한국서지표준센터의 납본 역할 강화를 포함하여 출판사와의 협력강화, 납본자료에 대한 보상, 납본제도에 대한 인식 제고 및 제도적 보상 등의 측면에서 고려되어야 할 부분이 있다.

• 제어로봇시스템학회논문지
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• 제8권11호
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• pp.928-934
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• 2002

A natural way to cope with fault tolerant control (FTC) problems is to modify the control parameters according to an online identification of the system parameters when a fault occurs. However. due to not only difficulties Inherent to the online multivariable identification in closed-loop systems, such as modeling errors, noise or the lack of excitation signals, but also long time requirement to identify the post-fault system and implemeutation of control problems during the identification process, we propose an alternative approach based on the observer-based fault detection and isolation (FDI) and model reference adaptive control (MRAC). The proposed robust fault diagnosis method is based on a bank of observers. We also propose a model reference adaptive control with changeable reference models according to the occurred faults. Simulation results of a flight control example show the validity and applicability of the proposed algorithms.

• 패션비즈니스
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• 제21권6호
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• pp.31-46
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• 2017

This study views the people's propensity to rely on others' evaluations as the interpersonal trust online despite a lack of personal interactions. Therefore, this study explores the underlying dimensions of interpersonal trust and examines how interpersonal trust influences trust in the e-tailer and behavioral intent. Data of 395 adults who had purchased apparel goods online were collected nationwide using an online questionnaire. Exploratory and confirmative factor analysis identified five underlying constructs of interpersonal trust online such as peer identification, ability, integrity, shared lifegoals, and benevolence. A structural equation modeling test was conducted to examine the relationships between interpersonal trust, trust in the e-tailer, and behavioral intent. Interpersonal trust influenced on trust in the e-tailer, specifically on trust in the e-tailer's competence which subsequently increased a customer's behavioral intent such as attitude toward the e-tailer and shopping intention. Although no direct effect of interpersonal trust on the behavioral intent was found, interestingly, the effects of the interpersonal trust on the e-tailer trust which derived the behavioral intent to purchase. This result suggests that marketers devise a more effective system and environment that can encourage the interpersonal trust between customers to build a strong trust in e-tailers. It also provides a theoretical framework of online trust in the way of classifying interpersonal trust and trust in e-tailers.

• Smart Structures and Systems
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• 제16권2호
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• pp.295-328
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• 2015

In recent years the monitoring of structural behavior through acquisition of vibrational data has become common practice. In addition, recent advances in sensor development have made the collection of diverse dynamic information feasible. Other than the commonly collected acceleration information, Global Position System (GPS) receivers and non-contact, optical techniques have also allowed for the synchronous collection of highly accurate displacement data. The fusion of this heterogeneous information is crucial for the successful monitoring and control of structural systems especially when aiming at real-time estimation. This task is not a straightforward one as measurements are inevitably corrupted with some percentage of noise, often leading to imprecise estimation. Quite commonly, the presence of noise in acceleration signals results in drifting estimates of displacement states, as a result of numerical integration. In this study, a new approach based on a time domain identification method, namely the Unscented Kalman Filter (UKF), is proposed for correcting the "drift effect" in displacement or rotation estimates in an online manner, i.e., on the fly as data is attained. The method relies on the introduction of artificial white noise (WN) observations into the filter equations, which is shown to achieve an online correction of the drift issue, thus yielding highly accurate motion data. The proposed approach is demonstrated for two cases; firstly, the illustrative example of a single degree of freedom linear oscillator is examined, where availability of acceleration measurements is exclusively assumed. Secondly, a field inspired implementation is presented for the torsional identification of a tall tower structure, where acceleration measurements are obtained at a high sampling rate and non-collocated GPS displacement measurements are assumed available at a lower sampling rate. A multi-rate Kalman Filter is incorporated into the analysis in order to successfully fuse data sampled at different rates.

• 전기학회논문지
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• 제63권3호
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• pp.376-382
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• 2014

E-Actuator is an essential part of an eVGT, it receives the command from the main ECU and controls the vane. An e-Actuator failure can cause an abrupt change in engine output and it may induce an accident. Therefore, it is required to detect anomalies in the e-Actuator in real time to prevent accidents. In this paper, an e-Actuator fault detection method using on-line parameter identification is proposed. To implement on-line fault detection algorithm, many constraints are considered. The test input and sampling rate are selected considering the constraints. And new recursive system identification algorithm is proposed which reduces the memory and MCU power dramatically. The relationship between the identified parameters and real elements such as gears, spring and motor are derived. The fault detection method using the relationship is proposed. The experiments with the real broken gears show the effectiveness of the proposed algorithm. It is expected that the real time fault detection is possible and it can improve the safety of eVGT system.

• 한국IT서비스학회지
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• 제17권1호
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• pp.155-170
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• 2018

This study examines a data-driven approach for software test automation at an online shopping site. Online shopping sites typically change prices dynamically, offer various discounts or coupons, and provide diverse delivery and payment options such as electronic fund transfer, credit cards, mobile payments (KakaoPay, NaverPay, SyrupPay, ApplePay, SamsungPay, etc.) and so on. As a result, they have to test numerous combinations of possible customer choices continuously and repetitively. The total number of test cases is almost 584 billion. This requires somehow automation of tests in settling payments. However, the record playback approach has difficulties in maintaining automation scripts due to frequent changes and complicated component identification. In contrast, the data-driven approach minimizes changes in scripts and component identification. This study shows that the data-driven approach to test automation is more effective than the traditional record playback method. In 2014 before the test automation, the monthly average defects were 5.6 during the test and 12.5 during operation. In 2015 after the test automation, the monthly average defects were 9.4 during the test and 2.8 during operation. The comparison of live defects and detected errors during the test shows statistically significant differences before and after introducing the test automation using the data-driven approach.

• Journal of international Conference on Electrical Machines and Systems
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• 제2권2호
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• pp.184-189
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• 2013

This paper proposes a method for improving the performance of a position sensorless control system for a slotless surface permanent magnet synchronous motor (SPMSM) in a very low-speed region. In position sensorless control based on a motor model, accurate motor parameters are required because parameter errors would affect position estimation accuracy. Therefore, online parameter identification is applied in the proposed system. The error between the reference voltage and the voltage applied to the motor is also affect position estimation accuracy and stability, thus it is compensated to ensure accuracy and stability of the sensorless control system. In this study, two voltage error compensation methods are used, and the effects of the compensation methods are discussed. The performance of the proposed sensorless control method is evaluated by experimental results.