• Journal of Electrical Engineering and Technology
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• 제10권1호
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• pp.102-108
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• 2015

This paper proposes a new fault isolation methodology for a smart protective device which plays an agent role on the smart grid distribution system with the distributed generation. It, by itself, determines accurately whether its protection zone is fault or not, identifies the fault zone and separates the fault zone through the exchange of fault information such as the current information and the voltage information with other protective devices using bi-directional communication capabilities on the smart grid distribution system. The heuristic rules are obtained from the structure and electrical characteristics determined according to the location of the fault and DG (Distributed Generation) when faults such as single-phase ground fault, phase-to-phase short fault and three-phase short fault occur on the smart grid distribution system with DG.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2003년도 ICCAS
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• pp.734-739
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• 2003

A new method of estimating the pose of a mobile-task robot is developed based upon an active calibration scheme. The utility of a mobile-task robot is widely recognized, which is formed by the serial connection of a mobile robot and a task robot. For the control of the mobile robot, an absolute position sensor is necessary. This paper proposes an active calibration scheme to estimate the pose of a mobile robot that carries a task robot on the top. The active calibration scheme is to estimate a pose of the mobile robot using the relative position/orientation to a known object whose location, size, and shape are known a priori. Through the homogeneous transformation, the absolute position/orientation of the camera is calculated and that is propagated to getting the pose of a mobile robot. With the experiments in the corridor, the proposed active calibration scheme is verified experimentally.

• Journal of Advanced Marine Engineering and Technology
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• 제28권4호
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• pp.577-586
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• 2004

Structural failures, such as crack initiation, often arise near the bolted parts of the side member and trunnion bracket in some commercial vehicles. The purpose of this paper is: 1) establishment of a simple and practical bolted joint modelling technique and 2) determination of the key design variables for design improvement based on numerical experiments. Once the bolted joint modelling technique is established through experimental verification, the key design variables must be identified in order to alleviate the level of the stress concentration near the problem region. Numerical results indicate that the torsional rigidity of the frame cross-section should be increased to reduce the level of the maximum stress at the actual crack initiation location.

• International Journal of Automotive Technology
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• 제8권5호
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• pp.599-603
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• 2007

An efficient optimum design process has been developed and applied to systematically design a lock-up clutch system for a torque converter used in an automatic transmission. A simulated annealing algorithm was applied to determine the parameters of the compressive helical damper springs in the clutch. The determination of the number, location, a number of turns, and deflection of damper springs plays an important role in reducing vibration and noise in the lock-up system. Next, FE-based shape optimization was coded to find the shape of the clutch disk that would satisfy the strength, noise and vibration requirements. Using the optimum code, parametric studies were performed to see how spring diameters and frequencies of clutch systems changed as the damper spring traveling angles and the torques were varied. Based on the optimum results, five different designs for clutches with different springs were fabricated and vibration analyses and tests were conducted to validate the accuracy of the proposed method. Results from the two methods show a good correlation.

• Journal of Platform Technology
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• 제6권4호
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• pp.11-17
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• 2018

In the smart intelligence information society, there is a possibility that the social dysfunction such as the personal information protection issue and the risk to the electronic surveillance society may be highlighted. In this paper, we refer to various categories and classify electronic surveillance into audio surveillance, visual surveillance, location surveillance, biometric information surveillance, and data surveillance. In order to respond to new electronic surveillance in the intelligent information society, it requires a change of perception that is different from that of the past. This starts with the importance of digital privacy and results in the right to self-determination of personal information. Therefore, in order to preemptively respond to the dysfunctions that may arise in the intelligent information society, it is necessary to further raise the awareness of the civil society to protect information human rights.

• 정보처리학회논문지C
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• 제18C권4호
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• pp.207-212
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• 2011

지능형 차량 네트워크(VANET)는 차량 간 (V2V, Vehicle to Vehicle) 또는 차량과 노변장치간 (V2I, Vehicle to Infrastructure)의 통신을 통해 서비스를 제공하는 기술이다. 지능형 차량 네트워크는 통신을 통해 유통되는 정보의 중요성을 고려해 볼 때 메시지의 인증 및 보안은 필수적인 요건이다. 현재 VANET의 보안성을 향상시키기 위해 다양한 인증기법이 연구되고 있다. 그중에서도 RAISE scheme은 차량 밀집환경에서의 인증을 익명으로 수행한다. 하지만 스킴에 사용된 기법인 k-anonymity는 익명성을 제공하는 대신 차량의 ID를 얻기 위해 불필요한 전수조사 연산을 수행해야 한다. 본 논문에서는 차량 간의 통신에 사용되는 무선 신호세기의 특성을 이용하여 위치기반 인증 및 암호화 기법을 제시하며 알고리즘의 정확도를 향상시키기 위해 3차원 상에서의 위치 선정 기법을 적용한다.

• 유통과학연구
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• 제20권6호
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• pp.1-10
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• 2022

Purpose: This research proposes a new modified Recency-Frequency-Monetary (RFM) model by extending the model with spatial analysis for supporting decision-makers in discovering the promotional target market. Research design, data and methodology: This quantitative research utilizes data-mining techniques and the RFM model to cluster a university's provider schools. The RFM model was modified by adapting its variables to the university's marketing context and adding a district's potential (D) variable based on heatmap analysis using Geographic Information System (GIS) and K-means clustering. The K-prototype algorithm and the Elbow method were applied to find provider school clusters using the proposed RFM-D model. After profiling the clusters, the target segment was assigned. The model was validated using empirical data from an Indonesian university, and its performance was compared to the Customer Lifetime Value (CLV)-based RFM utilizing accuracy, precision, recall, and F1-score metrics. Results: This research identified five clusters. The target segment was chosen from the highest-value and high-value clusters that comprised 17.80% of provider schools but can contribute 75.77% of students. Conclusions: The proposed model recommended more targeted schools in higher-potential districts and predicted the target segment with 0.99 accuracies, outperforming the CLV-based model. The empirical findings help university management determine the promotion location and allocate resources for promotional information distribution and student recruitment.

• 수산해양기술연구
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• 제47권4호
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• pp.344-355
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• 2011

We conducted experiments to compare the catch rate of bigeye tuna and yellowfin tuna between circle hooks and straight shank hook in the Korean tuna longline fishery at the eastern and central Pacific Ocean from 2005 to 2007. We analyzed difference of fork length, survival and hooking location between a circle hook and a straight shank hook for both tunas, respectively. There was no difference in the mean fork length size of yellowfin tuna caught on the two type of hook but bigeye tuna was significant. In case of survival, there was no difference between two hook type, but the difference of hooking location was significant for both species. We also analyzed to find determinants of both tunas catch rate using generalized linear models (GLMs) which were used latitude, longitude, year, month, depth, hook type, bait type and so on as independent variables. Spatial factors, latitude and longitude, and temporal factors, year and month, affected catch rate of bigeye tuna and yellowfin tuna. And also, depth such as a marine environment factor was influenced on catch rate.

• Journal of Electrical Engineering and Technology
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• 제6권2호
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• pp.147-153
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• 2011

This paper proposes a methodology using a tool based on the branch-parameter continuation power flow (BCPF) in order to restore the power flow solvability in unsolvable contingencies. A specified contingency from a set of transmission line contingencies is modeled, considering the transient analysis and practice in the Korean power system. This tool traces a solution path that satisfies the power flow equations with respect to the variation of the branch parameter. At a critical point, in which the branch parameter can move on to a maximum value, a sensitivity analysis with a normal vector is performed to identify the most effective compensation. With the sensitivity information, the location of the reactive power compensation is determined and the effectiveness of the sensitivity information is verified to restore the solvability. In the simulation, the proposed framework is then applied to the Korean power system.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2003년도 춘계학술대회 논문집
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• pp.79-85
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• 2003

One of unique characteristics of guided waves is a dispersive behavior that guided wave velocity changes with an excitation frequency and mode. In practical applications of guided wave techniques, it is very important to identify propagating modes in a time-domain waveform for determination of defect location and size. Mode identification can be done by measurement of group velocity in a time-domain waveform. Thus, it is preferred to generate a single or less dispersive mode But in many cases, it is difficult to distinguish a mode clearly in a time-domain waveform because of superposition of multi modes and mode conversion phenomena. Time-frequency analysis is used as efficient methods to identify modes by presenting wave energy distribution in a time-frequency. In this study, experimental guided wave mode identification is carried out in a steel plate using time-frequency analysis methods such as wavelet transform. The results are compared with theoretically calculated group velocity dispersion curves. The results are in good agreement with analytical predictions and show the effectiveness of using the wavelet transform method to identify and measure the amplitudes of individual guided wave modes.