• Journal of Power Electronics
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• 제16권1호
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• pp.287-296
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• 2016

Conventional maximum power point tracking (MPPT) methods are ineffective under partially shaded conditions because multiple local maximum can be exhibited on power-voltage characteristic curve. This study proposes an improved cuckoo search (ICS) MPPT method after investigating the cuckoo search (CS) algorithm applied in solving multiple MPPT. The algorithm eliminates the random step in the original CS algorithm, and the conception of low-power, high-power, normal and marked zones are introduced. The adaptive step adjustment is also realized according to the different stages of the nest position. This algorithm adopts the large step in low-power and marked zones to reduce search time, and a small step in high-power zone is used to improve search accuracy. Finally, simulation and experiment results indicate that the promoted ICS algorithm can immediately and accurately track the global maximum under partially shaded conditions, and the array output efficiency can be improved.

• Journal of Power Electronics
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• 제18권1호
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• pp.185-194
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• 2018

Interaction among multiple grid-connected inverters has a negative impact on the stable operations and power quality of a power grid. The interrelated influences of inverter inductor-capacitor-inductor filters constitute a high-order power network, and consequently, excite complex resonances at various frequencies. This study first establishes a micro-grid admittance matrix, in which inverters use deadbeat control. Multiple resonances can then be evaluated via modal analysis. For the active damping method applied to deadbeat control, the sampling frequency and the stable domain of the virtual damping ratio are also presented by analyzing system stability in the discrete domain. Simulation and experimental results confirm the efficiency of modal analysis and stable domain calculation in multi-inverter grid-connected systems.

• International Journal of Computer Science & Network Security
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• 제21권7호
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• pp.233-240
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• 2021

The majority of the Web's success can be related to its productivity and flexibility. Web Services (WSs) have the means to create new patterns for the delivery of software capabilities. The WS easily provides the use of existing components available via the Internet. WSs are a new trend that shares ubiquitous systems with others, so the popularity of the Web is increased day by day with their associated systems. This paper will explore and adopt the possibility of developing a technique that will automate instructors' scheduling of timetables within a Web services environment. This technique has an advantage that facilitates users to reduce the time cost and effort by reducing errors and costs for institutes. Providing dependable tables to avoid mistakes related to instituting schedules is ensured by an automated repetitive manual procedure. Automated systems are increasingly developed based on organizations and their customers. Still, the setting's difficulty of automation systems increases to rise as the system architecture and applications must accomplish various requirements and specifications of ever-demanding project scenarios. The automation system is composed of an operating system, platforms, devices, machines, control system, and information technology. This architecture provides more productivity and optimized services. The main purpose of this paper is to apply an automation system to enhance both quality and productivity. This paper also covers an agile method of proving an automation system by Finite State Machine (FSM) and Attributed Graph Grammar (AGG) tool.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2020년도 전력전자학술대회
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• pp.421-422
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• 2020

Hardware In-the-Loop simulation(HIL)은 실제 하드웨어 시스템을 실시간 모사할 수 있는 시뮬레이션 장비로 연구 및 개발 기간의 단축, 비용저감 등의 장점을 앞세워 다양한 전력전자 분야에 사용되고 있다. 실제 하드웨어를 그대로 모사하는 것이 HIL의 목적이기 때문에 HIL 장비는 검증의 실시간성과 출력된 결과의 정확성이 무엇보다도 중요하다고 할 수 있다. 하지만 코어간의 데이터를 주고받는 과정에서 HIL의 연산 속도 및 정확성을 저해하는 요인들이 발생하게 된다. 본 연구에서는 HIL 장비를 이용해 복잡한 시스템을 구현함에 있어서 연산속도 및 정확성을 저해하는 요인들을 찾아내고 이를 해결하기 위한 방법을 제안한다. 제안된 연산속도 개선 및 정확성 개선 방법의 타당성은 프로세서의 연산 속도 변화량, HIL 및 시험 결과 파형의 비교 분석을 통해 검증되었다.

• 한국BIM학회 논문집
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• 제12권2호
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• pp.49-59
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• 2022

The main idea of this study is to propose a BIM-based automation system drawing up a report of energy conservation plan in the architecture division. In order to obtain a building permit, an energy conservation plan must be prepared for buildings with a total floor area of 500m² or more under the current law. Currently, it is adopted as a general method to complete a report by obtaining data and drawings necessary for an energy conservation plan through manual work and input them directly into the verification system. This method takes a lot of effort and time in the design phase which ultimately increases the initial cost of the business, including the services of companies specialized in the environmental field. However, in preparation for mandatory BIM work process in the future, it is necessary to introduce BIM-based automatic creation system that has an advantage for shortening the whole process to enable rapid permission of energy-saving designs for buildings. There may be many methods of automation, but this study introduces how to build an application using Dynamo of Revit, in terms of utilizing BIM, and write an energy conservation plan by automatic completion of report through Dynamo and Excel's VBA algorithm, which can save time and cost in preparing the report of energy conservation plan compared with the manual process. Also we have insisted that the digital transformation of architectural process is a necessary for an efficient use of our automation system in the current energy conservation plan workflow.

• Advances in nano research
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• 제15권3호
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• pp.263-275
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• 2023

The electron transport properties of Y-type zigzag branched carbon nanotubes (CNTs) are of great significance for micro and nano carbon-based electronic devices and their interconnection. Based on the semi-empirical method combining tight-binding density functional theory and non-equilibrium Green's function, the electron transport properties between the branches of Y-type zigzag branched CNT are studied. The results show that the drain-source current of semiconducting Y-type zigzag branched CNT (8, 0)-(4, 0)-(4, 0) is cut-off and not affected by the gate voltage in a bias voltage range [-0.5 V, 0.5 V]. The current presents a nonlinear change in a bias voltage range [-1.5 V, -0.5 V] and [0.5 V, 1.5 V]. The tangent slope of the current-voltage curve can be changed by the gate voltage to realize the regulation of the current. The regulation effect under negative bias voltage is more significant. For the larger diameter semiconducting Y-type zigzag branched CNT (10, 0)-(5, 0)-(5, 0), only the value of drain-source current increases due to the larger diameter. For metallic Y-type zigzag branched CNT (12, 0)-(6, 0)-(6, 0), the drain-source current presents a linear change in a bias voltage range [-1.5 V, 1.5 V] and is symmetrical about (0, 0). The slope of current-voltage line can be changed by the gate voltage to realize the regulation of the current. For three kinds of Y-type zigzag branched CNT with different diameters and different conductivity, the current-voltage curve trend changes from decline to rise when the branch of drain-source is exchanged. The current regulation effect of semiconducting Y-type zigzag branched CNT under negative bias voltage is also more significant.

• Journal of Power Electronics
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• 제17권2호
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• pp.476-489
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• 2017

Under partial shading conditions (PSCs), multiple maximums may be exhibited on the P-U curve of string inverter photovoltaic (PV) systems. Under such conditions, heuristic methods are invalid for extracting a global maximum power point (GMPP); intelligent algorithms are time-consuming; and model-based methods are complex and costly. To overcome these shortcomings, a novel hybrid MPPT (MPF-IP&O) based on a model-based peak forecasting (MPF) method and an improved perturbation and observation (IP&O) method is proposed. The MPF considers the influence of temperature and does not require solar radiation measurements. In addition, it can forecast all of the peak values of the PV string without complex computation under PSCs, and it can determine the candidate GMPP after a comparison. Hence, the MPF narrows the searching range tremendously and accelerates the convergence to the GMPP. Additionally, the IP&O with a successive approximation strategy searches for the real GMPP in the neighborhood of the candidate one, which can significantly enhance the tracking efficiency. Finally, simulation and experiment results show that the proposed method has a higher tracking speed and accuracy than the perturbation and observation (P&O) and particle swarm optimization (PSO) methods under PSCs.

• 한국콘텐츠학회논문지
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• 제21권8호
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• pp.403-412
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• 2021

모바일 앱의 수가 기하급수적으로 늘어남에 따라 앱 개발과정에서 이루어지는 테스트의 자동화가 중요해지고 있다. 앱을 출시하기까지 다양한 유형의 테스트를 통해 반복적인 검증이 이루어지는데, 다양한 유형의 테스트 중 GUI 테스트를 중심으로 본 연구는 진행되었다. 안드로이드의 GUI 테스트 자동화 툴을 개발하기 위해서 안드로이드 앱 테스트의 UI Control 16가지와 Material Design Guideline에 대해서 기초 자료를 수집하였다. 그 후 기존 GUI 테스트 자동화 툴에 대해서 스크린 캡처 테스트 기반 2가지 툴과 소스코드 분석 테스트기반 4가지 툴 분석을 하였다. 분석을 통해 기존의 GUI 테스트 자동화 툴들은 시각적 설계, 인터페이스 사용 용이성, 컴포넌트 배치에 대해서는 고려하지 않고 있다는 점을 파악하였다. 이러한 기존 툴의 미비점을 보완하고자 새로운 GUI 테스트 자동화 툴 개발 방법으로 컴포넌트 선정이나 관리 분석 그리고 컴포넌트별 소스코드 예시로 탐색 메뉴나 버튼, 아이템 그룹화나 리스트에 관한 방법을 제시하였다. 본 연구는 GUI 테스트의 새로운 개발 방향을 제시함으로써 개발사의 안정적인 앱 배포에 기여할 수 있다는 점에서 의의가 있다.

• 한국재난정보학회 논문집
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• 제18권4호
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• pp.891-898
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• 2022

연구목적: 건설산업의 전 분야 및 전 단계에 대한 BIM 도입 의무화가 머지않아 시행될 만큼 BIM 업무의 실질적인 생산성 향상을 위한 기술 확보 방안이 필요하기 때문에 연구에서는 엔지니어가 BIM기반 설계 과정에서 건설기준을 검증할 수 있도록 BIM 모델링 절차별로 제작되는 주요 객체에 대해 자동으로 관련 건설기준을 검증할 수 있는 방안을 제시하였다. 연구방법: BIM기반 도로 설계 업무를 대상으로 모델링 업무 절차를 정의하고, 각 단계에서 도출되는 BIM 모델별로 관련 설계기준을 데이터베이스로 구축하는 방안을 마련하였다. 그리고 BIM기반 설계기준 검토 자동화 시스템 개발을 위한 프로세스도 제시하였다. 연구결과: Civil3D 및 Dynamo를 활용하여 BIM기반 설계기준 검토 자동화 모듈을 개발하고, 시범적용을 통해 설계과정에서 제작되는 BIM 객체의 건설설계기준 충족여부를 자동으로 신속하게 제공할 수 있음을 확인하였다. 결론: BIM기반 설계기준 검토 자동화 기술은 BIM 모델 제작 업무의 생산성 향상과 BIM 모델의 품질확보가 가능하다.

• 대한임베디드공학회논문지
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• 제19권2호
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• pp.73-81
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• 2024

Recently, mobile manipulators have been utilized in agriculture industry for weed removal and harvest automation. This paper proposes a domain adaptive fruit detection method for harvest automation, by utilizing OWL-ViT model which is an open-vocabulary object detection model. The vision-language model can detect objects based on text prompt, and therefore, it can be extended to detect objects of undefined categories. In the development of deep learning models for real-world problems, constructing a large-scale labeled dataset is a time-consuming task and heavily relies on human effort. To reduce the labor-intensive workload, we utilized a large-scale public dataset as a source domain data and employed a domain adaptation method. Adversarial learning was conducted between a domain discriminator and feature extractor to reduce the gap between the distribution of feature vectors from the source domain and our target domain data. We collected a target domain dataset in a real-like environment and conducted experiments to demonstrate the effectiveness of the proposed method. In experiments, the domain adaptation method improved the AP50 metric from 38.88% to 78.59% for detecting objects within the range of 2m, and we achieved 81.7% of manipulation success rate.