• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2001년도 춘계학술대회 논문집
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• pp.226-230
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• 2001

Electronic Speckle Pattern Interferometry (ESPI) has been recently developed and widely used because it has advantage to be able to measure surface deformations of engineering components and materials in industrial areas with non-contact. The spekle patterns to be formed with interference phenomena of scattering phenomena measure the out-of-plane deformations, together with the use of digital image equipment to process the informations included in the speckle patterns and the display consequent interferogram on a computer monitor. In this study, the experimental results of a canti-levered plate using ESPI were compared with those obtained from the simple beam theory. The ESPI results of the canti-levered plate analyzed by 4-step phase shifting method are close to the theoretical expectation. Also, out-0of-plane displacements of a spot welded canti-levered plate were measured by ESPI with 4-step phase shifting technique. The phase map of the spot welded canti-levered plate is quite different from that of the canti-levered plate without spot welding.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제18권3호
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• pp.685-703
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• 2024

Cloud computing provides each consumer with a large-scale computing tool. Different Cyber Attacks can potentially target cloud computing systems, as most cloud computing systems offer services to many people who are not known to be trustworthy. Therefore, to protect that Virtual Machine from threats, a cloud computing system must incorporate some security monitoring framework. There is a tradeoff between the security level of the security system and the performance of the system in this scenario. If strong security is needed, then the service of stronger security using more rules or patterns is provided, since it needs much more computing resources. A new way of security system is introduced in this work in cloud environments to the VM on account of resources allocated to customers are ease. The main spike of Fog computing is part of the cloud server's work in the ongoing study tells the step-by-step cloud server to change the tremendous measurement of information because the endeavor apps are relocated to the cloud to keep the framework cost. The cloud server is devouring and changing a huge measure of information step by step to reduce complications. The Medical Data Health-Care (MDHC) records are stored in Cloud datacenters and Fog layer based on the guard intensity and the key is provoked for ingress the file. The monitoring center sustains the Activity Log, Risk Table, and Health Records. Cloud computing and Fog computing were combined in this paper to review data movement and safe information about MDHC.

• 디지털융복합연구
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• 제16권8호
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• pp.381-391
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• 2018

이 연구는 스포츠윤리교육 프로그램에 대한 교육만족도 측정도구를 개발하고 그 타당성을 검증하는 데 목적이 있다. 연구의 목적을 달성하기 위하여 연구절차는 다음과 같이 3단계로 이루어졌다. 1단계에서는 스포츠윤리교육 프로그램과 관련된 선행연구를 분석하고, 개방형 질문지를 통해 얻어진 응답 결과를 토대로 예비문항을 구성하였다. 2단계는 예비조사단계로서 1단계에서 진행된 측정도구의 탐색적 요인분석과 확인적 요인분석을 통해 구인타당성을 확보하였다. 3단계는 본 조사 단계로서 차이 검증을 통해 측정도구의 외적타당도를 확보하였으며, 이를 통해 도출된 내용을 중심으로 교육만족도측정을 위한 문항을 구성하였다. 그 결과 교육내용 6문항, 강사역량 5문항, 교육효과 6문항, 총 3개 영역 17개 문항으로 스포츠윤리교육 프로그램의 교육만족도 측정도구가 개발되었다. 이 연구는 실효성 있는 스포츠윤리교육 프로그램 개발을 위한 기초자료로 활용될 수 있으며, 이를 통해 윤리적인 소양을 지닌 스포츠선수로 성장할 수 있는 기반이 마련됨으로써 궁극적으로 스포츠계의 변화와 발전에 기여할 수 있기를 기대한다.

• 전기화학회지
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• 제17권2호
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• pp.119-123
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• 2014

Here I report on how Fourier Transform Electrochemical Impedance Spectroscopy (FTEIS) overcomes the potential-current linearity problem encountered in the impedance calculation process. FTEIS was first invented to solve the time-related drawback of the conventional impedance technique. The dramatic time reduction of FTEIS enabled the real-time impedance measurement but brought about the linearity problem at the same time. While the conventional method circumvents the problem using the steady-state made by a sufficiently long measurement time, FTEIS cannot because of its real-time function. However, according to the mathematical development reported in this article, the potential step used in FTEIS is proved to avoid the linearity problem. During the step period, the potential and the current are linearized by the electrochemical impedance. Also, Fourier transform of the differentiated potential and current is proved to give the same result of the original ones.

• 대한기계학회논문집
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• 제19권4호
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• pp.1102-1115
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• 1995

An experimental study on the flow over the axisymmetric backward-facing step was carried out. The purpose of the present study is to investigate the effect of the boundary layer thickness at the separation point on the reattachment length and to understand the structure of the recirculating flows. Local mean and fluctuating velocity components were measured in the separating and reattaching axisymmetric turbulent boundary layer over the wall of convex cylinder placed in a water tunnel by using 2-color 4-beam fiber optics laser Doppler velocimetry. The study demonstrated that the reattachment length increases with increasing boundary layer thickness. It was also observed that the reverse flow velocity and turbulent kinetic energy decrease with an increase in the momentum thickness at the separation point. The measured velocity field suggests that the boundary layer thickness at the separation can affect definitely on the formation of corner eddy.

• 경영과학
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• 제31권4호
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• pp.135-150
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• 2014

This paper analyzes the operational efficiency of 91 individual retail stores in Seoul by a two-step procedure. In the first step, a data envelopment analysis (DEA) model is used to identify the efficiency scores. Three inputs (store size, number of items, and number of employees) and two outputs (sales and number of customers) are used for the efficiency measurement. In the second step, a Tobit regression model is used to identify the drivers of efficiency. DEA efficiency scores are used to test hypotheses on the impact of five independent variables, namely store age, number of items per store size, number of items per employee, trade area index, and number of competitors. Results of the Tobit analysis show that number of items per store size, number of items per employee, and number of competitors play a significant role in influencing the operational efficiency of retail stores. Managerial implications of the study are discussed.

• 대한전기학회논문지
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• 제45권2호
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• pp.283-288
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• 1996

This paper presents the development technology of standard shielded resistor divider for full lightning impulse voltage. The ability of large-capacity power apparatus to withstand lighting stroke is usually evaluated by means of full lightning impulse voltage. Lightning impulse voltage test has been essential to evaluate the insulation performance of electrical power apparatus. Recently international standard (IEC 60) on high voltage measurement techniques is being revised and requests a formal traceability of high voltage measurements. Therefore, general interest for this area has grown considerably during last years, and several international intercomparisons have already completed worldwide, i.e. Europe, Japan, America etc., In this viewpoint, we have also investigated the step response of the standard shielded resistor divider, which satisfies the IEC recommendation.

• Nuclear Engineering and Technology
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• 제53권11호
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• pp.3764-3771
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• 2021

Based on the convolutional neural network (CNN), a novel technique is investigated for lost gamma source detection in a room. The CNN is trained with the result of a GEANT4 simulation containing a gamma source inside a meshed room. The dataset for the training process is the deposited energy in the meshes of different n-step paths. The neural network is optimized with parameters such as the number of input data and path length. Based on the proposed method, the place of the gamma source can be recognized with reasonable accuracy without human intervention. The results show that only by 5 measurements of the energy deposited in a 5-step path, (5 sequential points 50 cm apart within 1600 meshes), the gamma source location can be estimated with 94% accuracy. Also, the method is tested for the room geometry containing the interior walls. The results show 90% accuracy with the energy deposition measurement in the meshes of a 5-step path.

• 한국지반신소재학회논문집
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• 제23권1호
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• pp.27-37
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• 2024

본 연구에서는 직접 알고리즘이 적용된 역해석 기법을 이용하여 실제 흙막이 벽체 현장 2개소를 대상으로 역해석을 수행하였으며 이를 유전알고리즘과 비교하여 역해석 기법의 적정성을 평가하였다. 또한, 프로그램의 효과적인 활용방안을 제시하기 위해 역해석 입력값인 계측 데이터를 굴착단계별로 다르게 입력한 후 역해석 결과(변위, 부재력)의 적용성을 검토하였다. 연구 결과, 직접알고리즘과 유전알고리즘 모두 적용성이 높으나 본 프로그램에 대한 최적화는 직접알고리즘이 더 잘 예측되는 것으로 평가되었다. 또한 직접알고리즘이 적용된 역해석 프로그램을 효과적으로 사용하기 위해서는 최종 굴착단계가 8단계~11단계인 현장을 대상으로 7단계 굴착시의 계측데이터를 입력할 경우 비교적 정확한 흙막이 거동을 예측할 수 있는 것으로 평가되었다.

• 대한기계학회논문집
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• 제19권9호
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• pp.2328-2341
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• 1995

An experimental study on the flow over the axisymmetric backward-facing step was carried out. The purposes of the present study are to investigate the effect of the free stream turbulence intensity on the reattachment length and to understand the turbulence structure of the recirculating flows. Local mean and fluctuating velocity components were measured in the separated and reattaching axisymmetric turbulent boundary layer over the wall of convex cylinder placed in a water tunnel by using 2-color 4-beam fiber optics laser Doppler velocimetry. As the free stream turbulence intensity increased, the reattachment length became shorter due to the enhanced mixing in the separated shear layer. It was also observed that the reverse flow velocity and turbulent kinetic energy increase with increasing free stream turbulence intensity. Spectral data and flow visualization showed that low-frequency motions occur in the separated flow behind a backward-facing step. These motions have a significant effect on the time-averaged turbulence data.