• The Journal of the Acoustical Society of Korea
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• v.42 no.3
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• pp.214-220
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• 2023

In this paper, we propose a method to improve texture recognition performance from haptic acceleration signals representing the texture characteristics of object surface materials by using a Conformer model that combines the advantages of a convolutional neural network and a transformer. In the proposed method, three-axis acceleration signals generated by impact sound and vibration are combined into one-dimensional acceleration data while a person contacts the surface of the object materials using a tool such as a stylus , and the logarithmic Mel-spectrogram is extracted from the haptic acceleration signal similar to the audio signal. Then, Conformer is applied to the extracted the logarithmic Mel-spectrogram to learn main local and global frequency features in recognizing the texture of various object materials. Experiments on the Lehrstuhl für Medientechnik (LMT) haptic texture dataset consisting of 60 materials to evaluate the performance of the proposed model showed that the proposed method can effectively recognize the texture of the object surface material better than the existing methods.

• Asia-pacific Journal of Multimedia Services Convergent with Art, Humanities, and Sociology
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• v.8 no.3
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• pp.571-578
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• 2018

The deteriorated pipline often causes the unexpected leakage and crack. Negligence and late maintenance leads the enormous damage for gas and water resource. This paper proposes early fault detection and diagnosis algorithm for pipeline using acoustic emission (AE) signals. Early fault detection method for pipeline compares the frequency amplitude of the spectrum to that of the spectrum in normal condition. Larger amplitude of the spectrum indicates abnormal condition. Early fault diagnosis algorithm uses support vector machines (SVM), which is trained for normal and abnormal conditions to diagnose the measured AE signal from the target pipeline. In the experiment, a pipeline testbed is constructed similarly to real industrial pipeline. Normal, 5mm cracked, 10mm holed pipelines are installed and tested in this study. The proposed fault detection and diagnosis technique is validated as an efficient approach to detect early faulty condition of pipeline.

• Proceedings of the Korea Water Resources Association Conference
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• 2020.06a
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• pp.47-47
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• 2020

하천 유사량 자료는 하천관리를 위해 기초적으로 활용되는 자료로 하천의 유지관리를 위한 유사량 자료의 측정은 필수적이다. 따라서, 현재 국내에서는 전국에 138개소의 국가유사량관측망에서 지속적인 유사량 측정을 수행하고 있지만, 기존의 재래식 부유사 채집기를 이용한 부유사 측정을 수행하고 있어 연간 약 20개소 내외에서만 직접조사가 수행되고 있고, 2019년도 기준 전국 138개소 중에서 2006년~2018년 동안 최소 1회 이상 유사량 측정을 수행한 지점은 40개소로 국가 유사량관측망의 약 29% 지점에 대해서만 조사가 수행되고 있다. 해외의 경우에도 기존 재래식 채집기를 통한 유사량 관측을 주로 수행하고 있지만 최근에는 기존 채집기를 이용한 유사량 조사방법의 고비용·저효율로 인한 시공간적 한계로 인해 대안기술이 개발되고 있다. 특히, 최근 해외에서는 ADCP를 활용한 유사량 측정 기술이 기존 부유사 채집기를 이용한 유사량 조사방법의 대안으로 시도되고 있다. ADCP를 이용한 유사량 측정방법은 ADCP의 초음파산란도를 활용하여 간접적으로 부유사의 농도를 추정하는 기술로 ADCP를 이용하여 유량자료과 함께 유사량 자료를 확보할 수 있을 것으로 기대되는 기술이다. 특히, 기존에 설치된 국가하천 자동유량측정장치(H-ADCP)에 적용이 가능하다면 다지점에서의 지속적인 유량측정과 함께 부유사 농도의 측정이 가능할 것으로 기대되고 있다. 이에 본 연구에서는 기존 국가하천에 설치되어 있는 자동유량측정장치(H-ADCP)의 초음파산란도를 활용한 부유사농도 측정 기술의 적용성을 검토하였다. 적용성의 검토를 위해 2016년 진동지점에서 수집된 H-ADCP 원시자료를 사용하여 초음파산란도를 활용한 부유사농도 측정 방법을 시범적으로 적용하였다. 적용결과, 실측 부유사농도와 H-ADCP로부터 추정된 부유사 농도를 비교를 통해서 H-ADCP를 활용한 부유사농도 측정 방법의 가능성을 확인할 수 있었지만, 기술적인 보완 및 개선이 필요할 것으로 판단되었다. 추후에는 지속적인 연구를 통해 ADCP 유사량 측정기술이 개발된다면 기존 부유사 채집기를 이용한 유사량 측정 방법의 대안으로 유사량 조사를 목적으로 활용이 될 수 있을 것으로 기대한다.

• Journal of Aerospace System Engineering
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• v.17 no.6
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• pp.100-107
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• 2023

Open-phase fault in a Permanent Magnet Synchronous Motor (PMSM) occurs due to disconnection of phases of motor windings or inverter switch failures. When an open-phase occurs, it leads to the generation of torque ripples and vibrations in the motor, which can have a critical impact on the safety of the vehicle (including aircraft) using a PMSM as an actuator. Therefore, rapid fault detection and classification are essential. This paper proposes a classification method for detecting open-phase faults and locating fault positions in a PMSM used in aircraft applications. The proposed approach uses an Extended Kalman Filter for fault diagnosis, and it subsequently classifies faults using a Multiple Model filter.

• The Journal of the Acoustical Society of Korea
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• v.35 no.4
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• pp.261-271
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• 2016

In the prediction of response of a pile in soil, numerical approaches such as a finite element method are generally applied due to complicate nonlinear behaviors of soils. However, the numerical methods based on the finite elements require heavy efforts in pile and soil modelling and also take long computing time. So their usage is limited especially in the early design stage in which principal dimensions and properties are not specified and tend to vary. On the contrary, theoretical approaches adopting linear approximations for soils are relatively simple and easy to model and take short computing time. Therefore, if they are validated to be reliable, they would be applicable in predicting responses of a pile in soil, particularly in early design stage. In case of wind turbines regarded in this study, it is required to assess their natural frequencies in early stages, and in this simulation the supporting pile inserted in soil could be replaced with a simplified elastic boundary condition at the bottom end of the wind turbine tower. To do this, analysis for a pile in soil is performed in this study to extract the spring constants at the top end of the pile. The pile in soil can be modelled as a beam on elastic spring by assuming that the soils deform within an elastic range. In this study, it is attempted to predict pile deformations and influence factors for lateral loads by means of the beam-on-spring model. As two example supporting structures for wind turbines, mono pile and suction pile models with different diameters are examined by evaluating their influence factors and validated by comparing them with those reported in literature. In addition, the deflection profiles along the depth and spring constants at the top end of the piles are compared to assess their supporting features.

• Information Systems Review
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• v.10 no.3
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• pp.257-287
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• 2008

Grounded in the prior literatures on acceptance and diffusion of IT and innovation in the level of organization research, 3 major constructional factors such as Motivation, IT resistance, and IT change management were investigated to suggest propositions from 15 multi-cases of PLM from 6 different companies in Automotive OEMs and suppliers, and we posited that the diffusion is continued only when motivation is stronger enough to overcome IT resistance as a fundamental finding and basis of this research on PLM acceptance and diffusion. The Motivation was found to be initiated and categorized from three different factors such as environmental factors, organizational factors, and technological factors, providing key propositions for further research: (1)The Automotive suppliers, contrary to OEM, are affected more by the demand of inter-connectivity as an environmental factor, while the other factors are similarly influencing to them, (2)The big organizations are influenced more by the champion, while the small organizations get influenced more by leader. (3)When the trend, inter-connectivity and complexity get stronger, the motivation gets more strongly influenced by the perceived benefit in the technological context. Regarding Change management we suggests IT change management is supportive to overcome IT resistance and also to enforce Motivation, and the critical mass exists differently according to the market maturity adopted, and more market matured technology has lower critical mass, implies less requirement of IT change management than less market matured technology.

• The Journal of the Korea Contents Association
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• v.14 no.4
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• pp.110-122
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• 2014

Korea's film industry has been growing over the last 10 years, and there has been much attention to the antecedents of film box office sales both academic and business communities. So far, previous research which explained success factors of film or movie mainly focused on 3 stages, production, distribution and screening. However, these 3 steps are heavily vertically integrated in Korea's firm industry unlike United States. Almost 130% of movie theaters are multiplex chain and operated by film production companies such as CJ and Lotte Entertainment In this situation, film sales are likely to he affected by movie theaters own facilities or location factors rather than movie contents. Based. on resource-based view and S-C-P paradigm, the authors examined "whether movie theater's facilities factors and trade area factors such as accessibility, competitive situation, and population have effect to movie theater's sales revenues. The results showed that the average occupancy of theater is the most important factor to movie theaters sales in both large and small cities. In large cities, movie theater's facilities factors which included vibration seat special sound system, premium movie theater, VIP lounge are relatively important than trade area factors. In contrast, in small cities, location factors and accessibility are the most important factors to movie theaters sales. We discuss the managerial and theoretical implication for the results and the specific limitations are suggested at the end of the paper.

• Korean Journal of Construction Engineering and Management
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• v.13 no.6
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• pp.121-132
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• 2012

The current estimation system of construction equipment cost was first introduced in 1960's when general contractors had ownership of equipment. However, most of construction equipment in construction sites has been rented from equipment leasing company these days. Therefore, the improvement of current cost estimation system is therefore inevitable in order to advance domestic construction industry. This study is aimed to suggest the improved system by analyzing nationwide market rental rates of major construction equipment. A user friendly prototype of actual database grounded on actual market rental rates collected from over 200 leasing companies in the nation was proposed. The database includes various rates and statistics analyzed by different form of contract as well as different region. Using the collected data, "The Cost Estimate System in Construction Equipment Database" was developed by using VBA(Visual Basic for Applications). The system makes users convenient to utilize the rental rates by choosing equipment and region, and various types of contract.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.15 no.1
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• pp.39-51
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• 2016

In accordance to rapid aging of population, the accidents of elderly pedestrian and pedestrian safety are becoming very important issues. In terms of smartphone technologies, older people are increasingly looking for useful and friendly ICT services that which can add a value on their silver life. This paper introduced a new IT-based service for elderly walking assist using a smart-phone accompanied by a wearable watch. We describe the functional requirements and a systems architecture model with an interface between a smart-phone and wearable watch. Moreover, this study attempted to verify what services are needed and to estimate elderly pedestrians' WTP (willingness to pay) for IT-based walking assistance device. A total of 189 elderly pedestrians were randomly surveyed through face-to-face interviews. The questionnaire consisted of 3 categories: (1) questions pertaining to socio-economic status, (2) 12 questions regarding walking attitudes, and (3) a question to measure WTP. With this gathered data, factor analysis and path model estimating were conducted. The results identified the elderly user requirements and the use-value of new innovative products for IT-based walking assistance services by two groups(latent elderly and elderly). The modeling result shows that elderly's service preference would increase the possibilities for the commercialization of IT-based walking device with improving their walking safety.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.11
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• pp.317-325
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• 2020

The development of a technique that can monitor the cracks, which is one of the typical types of damage, is necessary to secure the structural safety of elastically restrained cantilever-type beams with a tip mass that is used widely in infrastructure. Impedance techniques have been actively researched to detect cracks, and the cracks were estimated mainly by experimentally investigating the relationship between the crack and impedance signal. This study examined the correlation between the change in the impedance signals due to the crack, and the natural frequency obtained analytically. After updating the analysis model for the intact beam, the impedance signal was measured while gradually inflicting cracks in the cantilever-type beam, and the damage index was obtained. The results were compared with the natural frequencies calculated from the updated analysis model to investigate the correlation. A close correlation was observed between the experimentally obtained impedance damage index, and the analytically calculated natural frequency. Using this correlation, the structural characteristics could be evaluated more accurately from the damage estimation results, and the behavior of the structure could be predicted effectively using the analysis model.