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Visual Cooperation Based on LOS for Self-organization of Swarm Robots
정하민,김연균,김동헌 제어·로봇·시스템학회 2013 International Journal of Control, Automation, and Vol.11 No.1
In this study, an attempt has been made to incorporate visual cooperation among decentralized swarm robots for self-organization. Self-organization based on color recognition is presented to overcome the constraints faced in conventional self-organization based on centralized control, in which an external ceiling camera or beacon systems are used. In the proposed scheme, a singular association rule is introduced: a swarm robot considers line-of-sight (LOS) visual information only about its reference robot or a moving target. In particular, this paper presents the following set of cases pertaining to self-organization of swarm robots: 1) a case in which a robot loses a moving target from its LOS, 2) a case in which a robot loses a reference robot from its LOS, 3) a case in which a robot is lost, and 4) a case in which all robots lose the target from their LOS. Results of a simulation and an experiment on prey pursuit show that the proposed self-organization method can be effectively used for multiple mobile robots, despite the use of a simple association rule.
Potential-Function-based Shape Formation in Swarm Simulation
정하민,김동헌 제어·로봇·시스템학회 2014 International Journal of Control, Automation, and Vol.12 No.2
This paper presents a potential-function-based formation shape control scheme for swarm simulation. The potential function is designed to avoid collision among agents, approach a destination, and achieve a certain shape formation around the destination. The agents move in a swarm to the for-mation position, which is generated from a reference point and the neighboring agents. In the frame-work, a local minimum case created by combining the potential repulsed from neighboring robots and that attracted from a reference point is presented; herein, a robot escapes from a local minimum using a virtual escape point after recognizing the trapped situation. Similarly, in the proposed framework, for a well-equipped formation shape, potential functions are designed to maintain the same relative distance between neighboring robots on a formation line, which also satisfies scalability for the number of agents. The simulation results show that the proposed approach can effectively construct elliptical, diamond, and heart-shaped formations for swarm agents.
비강 및 부비동 종양에서의 p53, p21, Cyclin D1, Ki-67 발현
정하민,윤기중,이재훈 대한비과학회 2008 Journal of rhinology Vol.15 No.2
Background and Objectives:The goal of this study is to investigate alterations of cell-cycle-related molecules, including p53, p21, cyclin D1 and Ki-67, in tumors arising in the sinonasal region. Materials and Methods:The study materials were 16 specimens of normal nasal mucosa, 16 inverted papillomas (IPs) and 12 sinonasal squamous cell carcinomas. The p53, p21, cyclin D1 and Ki-67 expression was assessed by immunohistochemical staining. Result:IP and squamous cell carcinoma showed significant increase in the expression of p53, cyclin D1 and Ki-67 than normal mucosa. The expression of p53, cyclin D1 and Ki-67 of the carcinoma was stronger than the IP. But, the p21 expression was not associated with the IP and carcinoma. Conclusion:Increased levels of p53, cyclin D1 and Ki-67 expression correlate with increased cell proliferation in the tumors of sinonasal regions. These findings indicate that p53, cyclin D1 and Ki-67 expression may be useful markers for the dysregulations of cell kinetics in the tumors of sinonasal region. Background and Objectives:The goal of this study is to investigate alterations of cell-cycle-related molecules, including p53, p21, cyclin D1 and Ki-67, in tumors arising in the sinonasal region. Materials and Methods:The study materials were 16 specimens of normal nasal mucosa, 16 inverted papillomas (IPs) and 12 sinonasal squamous cell carcinomas. The p53, p21, cyclin D1 and Ki-67 expression was assessed by immunohistochemical staining. Result:IP and squamous cell carcinoma showed significant increase in the expression of p53, cyclin D1 and Ki-67 than normal mucosa. The expression of p53, cyclin D1 and Ki-67 of the carcinoma was stronger than the IP. But, the p21 expression was not associated with the IP and carcinoma. Conclusion:Increased levels of p53, cyclin D1 and Ki-67 expression correlate with increased cell proliferation in the tumors of sinonasal regions. These findings indicate that p53, cyclin D1 and Ki-67 expression may be useful markers for the dysregulations of cell kinetics in the tumors of sinonasal region.
비용 및 부비동염을 동반한 당뇨병 환자에서 발생한 안구주위 괴사성 근막염 1예
정하민,전경호,이상헌,이재훈 대한이비인후과학회 2014 대한이비인후과학회지 두경부외과학 Vol.57 No.3
Necrotizing fasciitis is a soft tissue infection characterized by necrosis of fascia and subcutaneous tissue. It rarely occurs in the craniocervical area but when it does, it can be fatal. Early recognition and prompt intervention are important in minimizing morbidity and mortality rates. We report on a diabetes mellitus patient with periorbital necrotizing fasciitis, which was treated with a combination of intravenous antibiotics and debridement of necrotic tissue and meticulous local wound management. Korean J Otorhinolaryngol-Head Neck Surg 2014;57(3):194-7
유니사이클 로봇을 위한 지역최소점 탈출을 갖춘 포메이션 알고리즘
정하민(Hahmin Jung),김동헌(Dong Hun Kim) 제어로봇시스템학회 2013 제어·로봇·시스템학회 논문지 Vol.19 No.4
This paper presents formation control based on potential functions for unicycle robots. The unicycle robots move to formation position which is made from a reference point and neighboring robots. In the framework, a local minimum case occurred by combination of potential repulsed from neighboring robots and potential attracted from a formation line is presented, in which the robot escapes from a local minimum using a virtual escape point after recognizing trapped situation. As well, in the paper, potential functions are designed to keep the same distance between neighboring robots on a formation line, i.e. the relative distance between neighboring robots on a formation line is controlled by a potential function parameter. The simulation results show that the proposed approach can effectively construct straight line, V, and polygon formation for multiple robots.
정하민(Hahmin Jung),김동헌(Dong Hun Kim) 한국지능시스템학회 2015 한국지능시스템학회논문지 Vol.25 No.1
본 논문은 다개체 로봇을 위한 랭크 기반의 포메이션을 다룬다. 여기서 제안되는 방법은 이웃한 두 대 로봇의 지역 위치를 이용한다. 전통적인 다개체 로봇의 포메이션을 위한 연구는 모든 로봇의 위치를 파악하기 위해 로봇과 중앙 컴퓨터사이의 통신을 필요로 한다. 그리고 전역좌표에서 모든 로봇의 위치를 참조하여 포메이션 형성 및 로봇 경로가 만들어 진다. 기존의 연구들과는 다르게 제안된 포메이션 형성 방법은 지역좌표에서 이웃한 두 대의 로봇 위치를 사용 한다. 따라서 제안된 방법은 여러 모양의 포메이션을 형성할 때 모든 로봇의 협력 관계는 필요하지 않고 주변의 이웃 로봇 위치를 개별적으로 이용한다. 시뮬레이션 결과는 제안된 방법이 효과적으로 포메이션을 형성할 수 있음을 보여준다. This paper presents a rank-based formation for multiple agents based on potential functions, where the proposed method uses the relative position of two neighboring agents. The conventional formation scheme of multiple systems requires communication between agents and a central computer to get the positions of all multiple agents. In the study, differently from previous studies, the formation scheme uses the relative position of two neighboring agents in a local coordinate system. In addition, it introduces a singular agent association that considers only the relative position between an agent and its neighboring agents, instead of multiple associations among all information about all agents. Furthermore, the proposed framework explores the benefits of different formation types. Extensive simulation results show that the proposed approach verifies the viability and effectiveness of the proposed formation.