• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 2017.04a
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• pp.37-38
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• 2017

최근 방제 및 예찰과 같은 농작업에 단일 UAV(Unmanned Aerial Vehicle)시스템이 적용되고 있지만, 가반하중과 체공시간 등 기존시스템의 문제가 점차 대두되면서 작업 시간을 보다 단축시키고 작업 효율을 극대화 할 수 있는 농업용 멀티 UAV시스템의 필요성이 증대되고 있다. 본 논문에서는 작업자가 다수의 농업용 UAV를 효과적으로 제어할 수 있는 분산군집제어 알고리즘을 제안하며 알고리즘 검증 및 평가를 위한 시뮬레이터를 소개한다. 분산군집제어는 UAV 제어 계층, VP(Virtual Point) 제어 계층, 원격제어 계층으로 이루어진 3계층 제어구조를 가진다. UAV 제어 계층에서 각 UAV는 point mass로 모델링 되는 VP의 이상적인 경로를 추종하도록 제어한다. VP 제어 계층에서 각 VP는 입력 $p_i(t)=u^c_i+u^o_i+u^{co}_i+u^h_i$-(1)을 받아 제어되는데 여기서, $u^c_i{\in}{\mathbb{R}}^3$는 VP 사이의 충돌방지제어, $u^o_i{\in}{\mathbb{R}}^3$는 장애물과의 충돌방지제어, $u^{co}_i{\in}{\mathbb{R}}^3$는 UAV 상호간의 협조제어, $u^h_i{\in}{\mathbb{R}}^3$는 작업자로부터의 원격제어명령이다. (1)의 제어입력에서 충돌방지제어는 각 $u^i_c:=-{\sum\limits_{j{\in}{\eta}_i}}{\frac {{\partial}{\phi}_{ij}^c({\parallel}p_i-p_j{\parallel})^T}{{\partial}p_i}}$-(2), $u^o_c:=-{\sum\limits_{r{\in}O_i}}{\frac {{\partial}{\phi}_{ir}^o({\parallel}p_i-p^o_r{\parallel})^T}{{\partial}p_i}}$-(3)로 정의되면 ${\phi}^c_{ij}$와 ${\phi}^o_{ir}$는 포텐셜 함수를 나타낸다. 원격제어 계층에서 작업자는 햅틱 인터페이스를 통해 VP의 속도를 제어하게 된다. 이때 스케일변수 ${\lambda}$에 대하여 VP의 원격제어명령은 $u^t_i(t)={\lambda}q(t)$로 정의한다. UAV 시뮬레이터는 리눅스 환경에서 ROS(Robot Operating Systems)를 기반한 3차원 시뮬레이터인 Gazebo상에 구축하였으며, 마스터와 슬레이브 간의 제어 명령은 TCPROS를 통해 서로 주고받는다. UAV는 PX4 기반의 3DR Solo 모델을 사용하였으며 MAVROS를 통해 MAVLink 통신 프로토콜에 접속하여 UAV의 고도, 속도 및 가속도 등의 상태정보를 받을 수 있다. 현재 멀티 드론 시스템을 Gazebo 환경에 구축하였으며, 추후 시뮬레이터 상에 분산군집제어 알고리즘을 구현하여 검증 및 평가를 진행하고자 한다.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.25 no.2
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• pp.70-74
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• 1989

This paper, described on the maneuverabilities of M.S. Cheju 402, the stern trawler (159 G.T.), training ship of Cheju National University which carried out the turning circle tests at helm angle 35$^{\circ}$ and 10$^{\circ}$, 20$^{\circ}$, 30$^{\circ}$Ztests of her. The results obtained were as follows; 1. The advances of the starboard and port turning circles were 79.1m, about 2.6 times of the length of the ship, and 81.4m, about 2.7 times of it, respectively. 2. The rates of speed reduction were about 0.49 together, and mean values of turning angular velocity of her at helm angle 35$^{\circ}$ into the starboard and port sides were 4.3$^{\circ}$/sec and 4$^{\circ}$/sec during the turning movement. 3. Overshoot angles of starboard side werelarger than those of port side at all Z tests, and mean values of them of the starboard and port sides at 10$^{\circ}$, 20$^{\circ}$, 30$^{\circ}$Z tests were 110.5$^{\circ}$ 20.5$^{\circ}$, 28.5$^{\circ}$ respectively. 4. The maneuvering indices K and T of experimental ship at 10$^{\circ}$, 20$^{\circ}$, 30$^{\circ}$, Z tests were 0.755 and 3.468, 0.566, and 1.621, and 0.481 and 1.547 respectively. Consequently, the experimental ship showed that her turning ability was more in effective as the helm angle was becomed larger and her obeying ability was more effective as it was becomed larger.

• Korean Security Journal
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• no.30
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• pp.61-83
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• 2012

Al-Qaeda follower who planned to attacks the Pentagon and the Assembly by unmanned aircraft equipped with explosives was caught in the dictionary in September 2011. In addition, high-performance unmanned aerial vehicles in the United States 'sentinel' of the technology being leaked to Iran in late 2011 was an accident. Terrorist attacks on the forces used unmanned aircraft will be the day the not too distant. The purpose of this research is to provide response plans against acts of terrorism utilizing unmanned aircrafts to prevent large losses of lives such as the terrorist attacks of September 11. Discussing in detail, this research suggests revising and newly implementing the definition and categorization of unmanned aircrafts as well as relevant punishment in current aeronautics regulations as an initial response against acts of terrorism utilizing unmanned aircrafts. This is in order to newly implement and revise current relevant regulations that inadequately address the rapidly developing and changing unmanned aircrafts which will lead to increased sense of alarm for the potential terrorists, and also to introduce a systematic tool to punish those who commit such acts by clearly establishing the grounds for punishment. Also, under the binary operating system over airspace currently implemented globally, it is impossible to identify and control the infiltration of airspace by unmanned aircrafts. Recognizing such limitations, this research suggests a combined operation of airspace for unmanned and manned aircrafts as a second way of response for acts of terrorism utilizing unmanned aircrafts. A systematic integrated operation of airspace will appropriately control unmanned/ manned aircrafts that were not previously reported or otherwise have deviated from navigation routes, and will be able to prevent terrorism attempts utilizing aircrafts beforehand.

• Journal of Intelligence and Information Systems
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• v.24 no.3
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• pp.45-66
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• 2018

Crowdfunding has become more popular than angel funding for fundraising by venture companies. Identification of success factors may be useful for fundraisers and investors to make decisions related to crowdfunding projects and predict a priori whether they will be successful or not. Recent studies have suggested several numeric factors, such as project goals and the number of associated SNS, studying how these affect the success of crowdfunding campaigns. However, prediction of the success of crowdfunding campaigns via non-numeric and unstructured data is not yet possible, especially through analysis of structural characteristics of documents introducing projects in need of funding. Analysis of these documents is promising because they are open and inexpensive to obtain. We propose a novel method to predict the success of a crowdfunding project based on the introductory text. To test the performance of the proposed method, in our study, texts related to 1,980 actual crowdfunding projects were collected and empirically analyzed. From the text data set, the following details about the projects were collected: category, number of replies, funding goal, fundraising method, reward, number of SNS followers, number of images and videos, and miscellaneous numeric data. These factors were identified as significant input features to be used in classification algorithms. The results suggest that the proposed method outperforms other recently proposed, non-text-based methods in terms of accuracy, F-score, and elapsed time.

• Journal of the Korea institute for structural maintenance and inspection
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• v.26 no.6
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• pp.82-92
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• 2022

This study aims to investigate the effect of total electrochemical cell resistance (TECR) on electrochemical impedance (EI) measurements of reinforced concrete (RC) by electrochemical impedance spectroscopy (EIS) using a three-electrode system. A series of experimental study is performed to measure electrochemical behavior of a steel bar embedded in a concrete cube specimen, with a side length of 200 mm, in various experimental conditions. Main variables include concrete dry conditions, coupling resistance between sensing electrodes and concrete surface, and area of the counter electrode. It is demonstrated that EI values remains stable when the compliant voltage of a measuring device is sufficiently great compared to the potential drop caused by TECR of concrete specimens. It is confirmed that the effect of the coupling resistance of TECR is far more influential than other two factors (concrete dry conditions and area of the counter electrode). The results in this study can be used as a fundamental basis for development of a surface-mount sensor for corrosion monitoring of reinforced concrete structures exposed to wet-and-dry cycles under marine environment.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.36 no.3
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• pp.175-185
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• 2000

This paper described on a basic study to organize fishing vessel control system in order to control efficiently fishing vessel in Korean offshore. It was digitalized ARPA image on the fishing processing of a fleet of purse seiner in conducting fishing operation at Cheju offshore in Korea as a digital camera and then simulated by used VTMS. Futhermore, it was investigated on the application of FVTMS which can control efficiently fishing vessels in fishing ground. The results obtained were as follows ; (1) It was taken 16 minutes and 35 minutes to casting and hauling net in fishing processing respectively. The length of rope pulled by scout boat was 200m, tactical diameter in casting net was 340.8m, turning speed was 6kts as well. (2) The processing of casting and hauling net was moved to SW, NE as results of simulation when the current direction and speed set into NE, 2kts and SW, 2kts respectively. Such as these results suggest that can predict to control the fishing vessel previously with information of fishing ground, fishery and ship's maneuvering, etc. (3) The control range of VTMS radar used in simulation was about 16 miles. Although converting from a radar of the control vessel to another one, it was continuously acquired for the vector and the target data. The optimum control position could be determined by measuring and analyzing to distance and direction between the control vessel and the fleet of fishing vessel. (4) The FVTMS(fishing vessel traffic management services) model was suggested that fishing vessels received fishing conditions and safety navigation information can operate safely and efficiently.