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Yongman Cho,Seungjae Lee,Changhwa Kim,Sangkyung Kim 대한전자공학회 2007 ITC-CSCC :International Technical Conference on Ci Vol.2007 No.7
Energy limitation of a sensor network is a very important feature which distinguishes it from traditional networks and a number of methods to saving energy consumption have been studied in sensor networks. Most of those works have focused on Network, MAC or PHY layer and the lifetime of a sensor network cannot be predetermined. But some sensor network might be able to survive for some specified time. In this works, we propose an energy consumption scheduling model, at application level of a node, that ensures pre-determined lifetime. To do this, first, we divide applications into six classes and define five operations of an application. Second, energy consumption model is proposed using those five operations and consumption energies of each operation are calculated by a statistical method. Finally, energy consumption schedules of each application are rebuilt for a node to survive for pre-determined lifetime, e.g. varying the period of response and sensing and the number of actuation, etc. Consequently, it is ensured for nodes to survive for the predetermined lifetime.
Kim, Yongman,Doh, Won Hui,Kim, Jeongjin,Park, Jeong Young American Chemical Society 2018 Langmuir Vol.34 No.21
<P>Porphyrin-derived molecules have received much attention for use in solar energy conversion devices, such as artificial leaves and dye-sensitized solar cells. Because of their technological importance, a molecular-level understanding of the mechanism for supramolecular structure formation in a liquid, as well as their stability under ultraviolet (UV) irradiation, is important. Here, we observed the self-assembled structure of free-base, copper(II), and nickel(II) octaethylporphyrin formed on Au(111) in a dodecane solution using scanning tunneling microscopy (STM). As evident in the STM images, the self-assembled monolayers (SAMs) of these three porphyrins on the Au(111) surface showed hexagonal close-packed structures when in dodecane solution. Under UV irradiation (λ = 365 nm), the porphyrin molecules in the SAM or the dodecane solution move extensively and form new porphyrin clusters on the Au sites that have a high degree of freedom. Consequently, the Au(111) surface was covered with disordered porphyrin clusters. However, we found that the porphyrin molecules decomposed under UV irradiation at 254 nm. Molecular-scale observation of the morphological evolution of the porphyrin SAM under UV irradiation can provide a fundamental understanding of the degradation processes of porphyrin-based energy conversion devices.</P> [FIG OMISSION]</BR>
Kim Yongman,Choi Joong Il Jake,Jeong Yongchan,Kim Young Jae,Park Jeong Young 한국물리학회 2023 Current Applied Physics Vol.50 No.-
In this paper, we present the design and performances of a beetle-type electrochemical scanning tunneling microscope (EC-STM) which allows horizontal tip motion at millimeter range (5 mm × 5 mm). With its symmetrical scanner design inducing a relatively low thermal drift, the beetle-type EC-STM has the desirable ability to operate in a variety of chemical reactions. Atom-resolved high-resolution STM images of highly oriented pyrolytic graphite (HOPG) and Au(111) surfaces in the liquid phase are presented to confirm the scan performance of the beetle-type EC-STM, which also provides in situ information on the electrode surface during electrochemical reactions, including adsorbed– and desorbed– electrolyte and metal electrodeposition. These systemically obtained STM images on the electrode surface clearly demonstrate the high stability of the newly developed EC-STM under reaction conditions.
센서 네트워크의 노드 응용 레벨에서 에너지 소모 계획 모델을 위한 연구
조용만(Yongman Cho),이승재(Seungjae Lee),김창화(Changhwa Kim),김상경(Sangkyung Kim),강태원(Tae-Won Kang) 한국정보과학회 2007 한국정보과학회 학술발표논문집 Vol.34 No.1D
센서 네트워크에서 에너지의 제한은 이전의 다른 많은 네트워크 시스템과 구별되는 특징을 가지게 한다. 따라서 센서 네트워크에서의 가장 중요한 연구 주제는 에너지를 절약하도록 하는 것에 초점이 맞춰진다. 기존의 센서 네트워크에서는 주로 Network, Mac, Phy 계층에서 연구가 진행되었으며, 또한 사용자가 센서 네트워크의 Lifetime을 미리 정할 수 없었다. 하지만, 어떤 센서 네트워크에서는 어떤 특정한 시간까지 생존할 필요가 있을 것이다. 이 논문에서는 미리 정해진 Lifetime을 보장하는 노드의 응용 수준에서의 에너지 소모 모델을 제공한다. 이와 같은 일을 하기위해서, 첫 번째로, 센서 네트워크에서의 응용을 6가지로 구분하고, 응용에서 필요로 되는 5가지 연산을 정의했다. 두 번째로 이러한 5가지의 연산을 포함하는 에너지 소모 모델을 만들었으며, 이것을 가지고 각각의 연산에서 소모되는 에너지를 통계적인 기법을 통해서 계산한다. 마지막으로 노드가 미리 정해진 시간까지 생존하도록 각각의 노드에서 응용의 에너지 소모 계획을 다시 작성한다. 예를 들면, 응답주기와 센싱주기의 변경을 통하여 에너지의 소모를 줄일 수 있다. 결과적으로 이러한 일들은 노드가 정해진 시간까지 생존하도록 보장해 준다.
Gossiping Route Protocol을 이용한 공기오염감지시스템에 관한 연구
박용만(YongMan Park),김희식(Hiesik Kim),김규식(GyuSik Kim),이문규(MoonGyu Lee),오드게렐(Odgerel Ayurzana),권종원(JongWon Kwon),구상준(SangJun Koo),오시환(ShiHwan Oh),김동기(DongKi Kim),조익균(IkKyun Jo),박정훈(JeongHun Park) 대한전기학회 2007 대한전기학회 학술대회 논문집 Vol.2007 No.10
Wireless Sensor Networking is state of the art technology that has a wide range of potential applications. Sensor network generally consists of a large number of distributed nodes that organize themselves into a multi-hop wireless network. Each node has one or more sensors, embedded processors and low-power radios, and is normally battery operated because of small size. In this paper wireless sensor networking technology applies to the environment monitoring system in the underground. This system can monitor a pollution level of the underground in realtime for keeping up a comfortable environment.