• 조명전기설비학회논문지
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• 제23권8호
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• pp.41-47
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• 2009

디지털 기술 기반의 차세대 변전시스템과 관련하여 프로세스 버스까지 확장된 변전자동화시스템 구현에 관한 연구가 국내외에서 활발히 진행 중에 있다. 특히 IEC 61850 국제 규격이 적용된 머징유닛(Merging Unit)은 프로세스 기반 변전자동화시스템의 핵심 구성요소로 그 관심이 매우 크다. 본 논문에서는 변전소의 CT와 VT를 통합 전압 전류의 값을 IEC 61850 기반의 디지털 값인 SV(Sampled Value)로 변환하여 보내는 머징유닛의 기능과 통신서비스에 대한 적합성 성능 검증에 대한 방안을 제시하고 머징유닛을 시험할 수 있는 시험시스템을 보여주고자 한다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1994년도 Proceedings of the Korea Automatic Control Conference, 9th (KACC) ; Taejeon, Korea; 17-20 Oct. 1994
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• pp.665-671
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• 1994

Some extended results in the study of two-position alignment for strapdown inertial navigation system are presented. In [1], an observability analysis for two-position alignment was done by analytic rank test of the stripped observability matrix and numerical calculation of the error covariance propagation using ten-state error model. In this paper, it is done by an analytic approach which utilizes the nonsingular condition of the determinant of simplified stripped observability matrix and by numerical calculation of the error covariance propagation accomplished in more cases than [1], and the twelve-state error model including vertical channel is used instead of ten-state error model. In addition, it is confirmed that this approach more clearly produces the same result as shown in the original work in terms of complete observability and there exist some better two-position configurations than [1] using the twelve-state error model.

• Smart Structures and Systems
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• 제21권5호
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• pp.537-548
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• 2018

A tunnel deformation monitoring system is developed with the use of fiber Bragg grating (FBG) sensing technique, aiming at providing continuous monitoring of railway tunnel deformation in the long term, and early warning for the rail service maintainers and authorities to avoid catastrophic consequences when significant deformation occurs. Specifically, a set of FBG bending gauges with the ability of angle measurement and temperature compensation is designed and manufactured for the purpose of online monitoring of tunnel deformation. An overall profile of lateral tunnel displacement along the longitudinal direction can be obtained by implementing an array of the FBG bending gauges interconnected by rigid rods, in conjunction with a proper algorithm. The devised system is verified in laboratory experiments with a test setup enabling to imitate various patterns of tunnel deformation before the implementation of this system in an in-service high-speed railway (HSR) tunnel.

• 대한공간정보학회지
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• 제21권1호
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• pp.39-44
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• 2013

도시지역에서 산소를 발생하고 이산화탄소를 감소시킬 수 있는 중요한 지상객체로 수목을 뽑을 수 있다. 이러한 수목의 관리를 위하여 라이다 자료를 이용한 많은 연구가 진행되고 있다. 그러나 국내에서 라이다 자료처리 소프트웨어가 미비하여 국외 소프트웨어에 의존하고 있다. 이에 본 연구에서는 라이다 자료에서 수목을 자동으로 추출할 수 있는 자동화 공정을 제안하였다. 제안한 공정에는 라이다 자료의 분류, 건물영역, 수목 등을 자동으로 추출할 수 있는 기능이 개발되었다. 제안한 공정은 용인지역의 연구대상지에 적용하여 실험을 수행하였으며 약 88%의 수목이 자동화 공정을 통해서 추출되었다.

• 한국생산제조학회지
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• 제26권2호
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• pp.230-237
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• 2017

Various drones have extended application area very fast. In this paper, we define two contradictions in designing a portable-size drone by using TRIZ technique. The first is a physical contradiction between high rigidity and good portability, and the second is a technical contradiction between high stability and good portability. Through TRIZ technique, six design principles, which guide direction for optimal design, were driven. Consequently, an umbrella mechanism and design criteria were proposed for a portable-size drone. Detail design is verified through finite element method. Test results for the portable-size prototype drone show good performance, and prove its usefulness to be equivalent to a general full-size drone.

• Journal of Magnetics
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• 제21권1호
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• pp.65-71
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• 2016

To increase the retaining force, a novel design for a concentric, bi-directional, electromagnetic valve actuator that contains double-layer permanent magnets is presented in this paper. To analyze the retaining-force change caused by the magnets, an equivalent magnetic circuit (EMC) model is established, while the EMC circuit of a double-layer permanent-magnet valve actuator (DLMVA) is also designed. Based on a 3D finite element method (FEM), the calculation model is built for the optimization of the key DLMVA parameters, and the valve-actuator optimization results are adopted for the improvement of the DLMVA design. A prototype actuator is manufactured, and the corresponding test results show that the actuator satisfies the requirements of a high retaining force under a volume limitation; furthermore, the design of the permanent magnets in the DLMVA allow for the attainment of both a high initial output force and a retaining force of more than 100 N.

• Journal of Power Electronics
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• 제17권6호
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• pp.1672-1682
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• 2017

For grid-connected LCL-filtered inverters, the inverter-side current can be used as the control object with one current sensor for both LCL resonance damping and over-current protection, while the grid-voltage feedforward or harmonic resonant compensator is used for suppressing low-order grid current harmonics. However, it was found that the grid current harmonics were high and often beyond the standard limitations with this control. The limitations of the inverter-side current control in suppressing low-order grid current harmonics are analyzed through inverter output impedance modeling. No matter which compensator is used, the maximum magnitudes of the inverter output impedance at lower frequencies are closely related to the LCL parameters and are decreased by increasing the control delay. Then, to improve the grid current quality without complicating the control or design, this study proposes designing the filter capacitance considering the current harmonic constraint and using a PWM mode with a short control delay. Test results have confirmed the limitation and verified the performance of the improved approaches.

• Journal of Information Processing Systems
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• 제17권6호
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• pp.1057-1070
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• 2021

Case-related news filtering is crucial in legal text mining and divides news into case-related and case-unrelated categories. Because case-related news originates from various fields and has different writing styles, it is difficult to establish complete filtering rules or keywords for data collection. In addition, the labeled corpus for case-related news is sparse; therefore, to train a high-performance classification model, it is necessary to annotate the corpus. To address this challenge, we propose topic-enhanced positive-unlabeled learning, which selects positive and negative samples guided by topics. Specifically, a topic model based on a variational autoencoder (VAE) is trained to extract topics from unlabeled samples. By using these topics in the iterative process of positive-unlabeled (PU) learning, the accuracy of identifying case-related news can be improved. From the experimental results, it can be observed that the F1 value of our method on the test set is 1.8% higher than that of the PU learning baseline model. In addition, our method is more robust with low initial samples and high iterations, and compared with advanced PU learning baselines such as nnPU and I-PU, we obtain a 1.1% higher F1 value, which indicates that our method can effectively identify case-related news.

• 대한인간공학회지
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• 제36권2호
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• pp.87-108
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• 2017

Objective: The purpose of this study was to precede the acceptance study based on automation steps and user experience that was lacked in the past study on the core technology of autonomous vehicle, ADAS. The first objective was to construct the acceptance model of ADAS technology that is the core technology, and draw factors that affect behavioral intention through user experience-based evaluation by applying driving simulator. The second one was to see the change of factors on automation step of autonomous vehicle through the UX/UA score. Background: The number of vehicles with the introduction of ADAS is increasing, and it caused change of interaction between vehicle and driver as automation is being developed on the particular drive factor. For this reason, it is becoming important to study the technology acceptance on how driver can actively accept giving up some parts of automated drive operation and handing over the authority to vehicle. Method: We organized the study model and items through literature investigation and the scenario according to the 4 stages of automation of autonomous vehicle, and preceded acceptance assessment using driving simulator. Total 68 men and woman were participated in this experiment. Results: We drew results of Performance Expectancy (PE), Social Influence (SI), Perceived Safety (PS), Anxiety (AX), Trust (T) and Affective Satisfaction (AS) as the factors that affect Behavioral Intention (BI). Also the drawn factors shows that UX/UA score has a significant difference statistically according to the automation steps of autonomous vehicle, and UX/UA tends to move up until the stage 2 of automation, and at stage 3 it goes down to the lowest level, and it increases a little or stays steady at stage 4. Conclusion and Application: First, we presented the acceptance model of ADAS that is the core technology of autonomous vehicle, and it could be the basis of the future acceptance study of the ADAS technology as it verifies through user experience-based assessment using driving simulator. Second, it could be helpful to the appropriate ADAS development in the future as drawing the change of factors and predicting the acceptance level according to the automation stages of autonomous vehicle through UX/UA score, and it could also grasp and avoid the problem that affect the acceptance level. It is possible to use these study results as tools to test validity of function before ADAS offering company launches the products. Also it will help to prevent the problems that could be caused when applying the autonomous vehicle technology, and to establish technology that is easily acceptable for drivers, so it will improve safety and convenience of drivers.

• 한국정보전자통신기술학회논문지
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• 제15권2호
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• pp.95-102
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• 2022

신재생에너지 확대를 위한 배전자동화시스템의 안정성 평가를 위한 연구이다. 정부는 재생에너지 3020 이행계획 정책을 통해 2030년까지 신재생에너지를 확대하여 국민의 삶의 질을 높이는 참여형 에너지 체계로 전환할 계획이다. 정부는 2030년까지 재생에너지 발전량 비중을 국내 보급 에너지의 20%로 목표 설정하였다. 신규 설비용량의 95% 이상을 태양광 풍력 등 청정에너지로 설립할 계획이다. 재생에너지 보급 확대로 에너지 신사업과 분산전원 산업이 육성되어 과거의 대규모 전원 개발이 아닌 근거리, 저압, 소규모 발전이 급속히 확대되었다. 이런 수요로 인해 배전 설비 운영의 중요성이 대두 되었고 배전자동화시스템이 필요성 증대되고 있다. 본 논문에서는 배전자동화시스템의 성능 및 기능 평가를 위한 배전시뮬레이터 개발에 대해 다루었고 이와 배전자동화시스템과의 연동시험 결과를 제시한다. 배전계통에 진보된 시스템을 도입하기 위해서는 송변전시스템의 장점을 취해야 한다. 배전시스템에서 DNP3.0프로토콜을 사용하고 송배전시스템에서 IEC61850 프로토콜을 사용한다. 이 두 프로토콜을 배전자동화시스템에서 혼용하여 사용시 제어, 모니터링 등의 운영에 대한 기능과 성능을 충족한다는 결론을 보였다.