• 한국통신학회논문지
• /
• 제35권5A호
• /
• pp.466-473
• /
• 2010

에너지 효율성과 같은 센서 네트워크에 중요한 요소들을 보장하기 위한 트리기반 프로토콜들이 여럿 제시되었다. 하지만 선박이나 해양 분야와 같이 베이스 노드의 이동성이 큰 네트워크 환경을 전제로 한 토폴로지에 대한 연구는 부족하였다. 본 논문에서는 베이스 노드의 이동성이 큰 센서 네트워크 환경에 적합한 토폴로지로 최소 Wiener 수 신장트리를 제안한다. 가중치 있는 그래프로부터 최소 Wiener 수를 가진 신장트리를 구하는 문제는 NP-hard로 알려져 있다. 문제 해결을 위해 분기 한정 알고리즘을 설계하고 대표적인 신장트리 중 하나인 최소신장트리를 대상으로 1라운드 패킷 전송에 필요한 전송 거리 및 에너지 소모량, 네트워크 수명을 모의실험을 통해 비교하였다. 전송 거리와 에너지 소모량은 제시한 트리가 최소신장트리에 비해 우수하였지만 네트워크 수명은 오히려 열등함을 알 수 있었다.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• 제14권4호
• /
• pp.1837-1860
• /
• 2020

We propose a general framework for studying resource allocation problem and the tradeoff between spectral efficiency (SE) and energy efficiency (EE) for downlink traffic in power domain-non-orthogonal multiple access (PD-NOMA) and device to device (D2D) based heterogeneous cloud radio access networks (H-CRANs) under imperfect channel state information (CSI). The aim is jointly optimize radio remote head (RRH) selection, spectrum allocation and power control, which is formulated as a multi-objective optimization (MOO) problem that can be solved with weighted Tchebycheff method. We propose a low-complexity algorithm to solve user association, spectrum allocation and power coordination separately. We first compute the CSI for RRHs. Then we study allocating the cell users (CUs) and D2D groups to different subchannels by constructing a bipartite graph and Hungrarian algorithm. To solve the power control and EE-SE tradeoff problems, we decompose the target function into two subproblems. Then, we utilize successive convex program approach to lower the computational complexity. Moreover, we use Lagrangian method and KKT conditions to find the global optimum with low complexity, and get a fast convergence by subgradient method. Numerical simulation results demonstrate that by using PD-NOMA technique and H-CRAN with D2D communications, the system gets good EE-SE tradeoff performance.

• 한국정보기술학회 영문논문지
• /
• 제9권1호
• /
• pp.103-113
• /
• 2019

Motivation: Polymerized actin-based cytoskeletal structures are crucial in shape, dynamics, and resilience of a cell. For example, dynamical actin-containing ruffles are located at leading edges of cells and have a significant impact on cell motility. Other filamentous actin (F-actin) bundles, called stress fibers, are essential in cell attachment and detachment. For this reason, their mechanistic understanding provides crucial information to solve practical problems related to cell interactions with materials in tissue engineering. Detecting and counting actin-based structures in a cellular ensemble is a fundamental first step. In this research, we suggest a new method to characterize F-actin wrapping fibers from confocal fluorescence image stacks. As fluorescently labeled F-actin often envelope the fibers, we first propose to segment these fibers by diminishing an energy based on maximum flow and minimum cut algorithm. The actual actin is detected through the use of bilateral filtering followed by a thresholding step. Later, concave actin bundles are detected through a graph-based procedure that actually determines if the considered actin filament is enclosing the fiber.

• 한국에너지공학회:학술대회논문집
• /
• 한국에너지공학회 2010년도 춘계학술 발표회
• /
• pp.59-63
• /
• 2010

토치 점화 장치의 연소 특성을 파악하기 위하여 7개의 각기 다른 토치 점화 장치를 설계하였다. 토치 점화장치의 오리피스 직경에 따른 특성을 파악하기 위하여, 토치 점화 장치의 체적과 높이는 고정하고, 오리피스 직경을 4mm에서 16mm까지 2mm씩 증가시키며 실험하였다. 초기 화염 생성 및 전파는 질량 연소율과 연소 촉진율로 분석하였다. 질량 연소율과 연소 촉진율을 계산하기 위하여 정적 연소실 내의 평균 압력을 측정하였다. 또한 shadow graph법을 이용하여, 초기 화염 생성과 화염 전파과정 전 영역을 가시화하였다. 토치 점화 장치를 사용한 경우에는 일반적인 스파크 점화와 비교하여 질량 연소율의 기울기가 증가하였고, 연소 촉진율도 개선된것을 확인하였다. 또한 가시화된 이미지를 확인한 결과 토치 점화 장치를 사용하면 초기 화염 발달 단계에서 화염이 난류 화염으로 천이되어 연소가 촉진된것을 확인하였다.

• 한국태양에너지학회:학술대회논문집
• /
• 한국태양에너지학회 2011년도 춘계학술발표대회 논문집
• /
• pp.31-35
• /
• 2011

Photovoltaic modules are well known to be one of the most eco generation of electricity. But usually study solar cell. Otherwise, PV modules are also important in power generation. We have to check other subsidiary materials. In this work benefit of using optically superior encapsulation materials(EVA) in generation temperature is demonstrated. Optical characterization of three EVA products demonstrates reduced transmission in the visible ray region of the solar spectrum. It will have a decisive effect to the module efficiency. Test is shown reduction of reflectance and transmittance. Reflections is dependent on the low iron glass. It can be seen between a specific wave length(240~350mm) about 1%. Transmittance in the entire ray region of light is markedly reduced to depending on the temperature rise. The graph is shown optical properties on EVA. Transmission was reduced. about 1%.

• 산업경영시스템학회지
• /
• 제42권1호
• /
• pp.87-94
• /
• 2019

A wireless sensor network is emerging technology and intelligent wireless communication paradigm that is dynamically aware of its surrounding environment. It is also able to respond to it in order to achieve reliable and efficient communication. The dynamical cognition capability and environmental adaptability rely on organizing dynamical networks effectively. However, optimally clustering the cognitive wireless sensor networks is an NP-complete problem. The objective of this paper is to develop an optimal sensor network design for maximizing the performance. This proposed Ranking Artificial Bee Colony (RABC) is developed based on Artificial Bee Colony (ABC) with ranking strategy. The ranking strategy can make the much better solutions by combining the best solutions so far and add these solutions in the solution population when applying ABC. RABC is designed to adapt to topological changes to any network graph in a time. We can minimize the total energy dissipation of sensors to prolong the lifetime of a network to balance the energy consumption of all nodes with robust optimal solution. Simulation results show that the performance of our proposed RABC is better than those of previous methods (LEACH, LEACH-C, and etc.) in wireless sensor networks. Our proposed method is the best for the 100 node-network example when the Sink node is centrally located.

• 설비공학논문집
• /
• 제10권5호
• /
• pp.523-534
• /
• 1998

The convection heat transfer on horizontal circular tube is studied as a conjugated heat transfer problem. With uniform heat generation in a cylindrical heater placed in a cross flow boundary condition, heat flow that is conducted along the wall of the heater creates a non-isothermal surface temperature and non-uniform heat flux distribution. In the present investigation, the effects of circumferential wall heat conduction on convection heat transfer are investigated for the case of forced convection around horizontal circular tube in cross flow of air and water. Non-dimensional conjugation parameter $ K^*$ which can be deduced from the governing energy differential equation should be used to express the effect of circumferential wall heat conduction. Two-dimensional temperature distribution$ T({\gamma,\theta})$ is presented. The influence of circumferential wall heat conduction is demonstrated on graph of local Nusselt number.

• 한국정보처리학회:학술대회논문집
• /
• 한국정보처리학회 2011년도 추계학술발표대회
• /
• pp.675-678
• /
• 2011

무선센서 네트워크는 많이 알려진 연구분야 중 하나이다. 스마트 그리드 나 자동화 시스템 등에 많이 적용된다. 산업장에서 사용되는 무선센서 네트워크 관련표준은 Ziebee, WirelessHART, ISA100.11a 등이 있다. ISA100.11a 는 그래프 라우팅 이라 불리 우는 간단하고 신뢰적인 그래프 라우팅 방법을 제안한다. 그래프 라우팅은 라우팅 테이블이 없는 고정된 라우팅이다. ISA100.11a 에서는 구체적인 라우팅 구성방법에 대해서는 설명되어 있지 않다. 따라서 본 논문에서는 베이스 라인(Base Line)을 이용한 에너지 효율적이고 신뢰적인 그래프 라우팅 구성방법을 제시한다.

• 제어로봇시스템학회:학술대회논문집
• /
• 제어로봇시스템학회 1987년도 한국자동제어학술회의논문집; 한국과학기술대학, 충남; 16-17 Oct. 1987
• /
• pp.670-673
• /
• 1987

The structure of chemical process has become increasingly complex, due to better management of energy and raw materials. As a consequence, the design of control systems for complete plants now constitutes the focal point of engineering interest, rather than controller designs for single processing units. Instead of traditional methods based on complex mathematical model, chemical processes are represented by structural array and cause-and-effect graph to apply non-numerical problem-solving techniques. A systematic logical procedure to synthesize alternatives of control system structure and some heuristic rules to select a feasible solution from the vast number of alternatives that are possible are considered in this study.

• Journal of Acupuncture Research
• /
• 제30권1호
• /
• pp.1-11
• /
• 2013

Objectives : The 7-zone-diagnostic system is a device for predetermining bodily locations by measuring the energy of the living body. The purpose of this study is to examine correlations between gastroscopy results and zone-5 data from the 7-zone-diagnostic system. Methods : This study was carried out with data from gastroscopy procedures. It involved 115 patients who had been diagnosed with gastritis, esophagitis, or gastric ulcers. These patients were divided into three groups according to the different patterns of zone-5 factors AA, FL2 and FL1. Group A was made up of patients for whom the red bar graph of zone-5 was higher than the normal range for factor AA. Group B was made up of patients for whom the red bar graph of zone-5 was within the normal range for factor AA. Group C was made up of patients for whom the red bar graph of zone-5 was lower than the normal range for factor AA. Group D E and F were made up of same way as group A B and C for factor FL2. Group G H and I were made up of same way as group A B and C for factor FL1. After the collection of gastroscopy results and data on zone-5 from the 7-zone-diagnostic system, the data was analyzed statistically. Results : 1. Group D had a higher ratio of medication than group E, and this result was statistically significant. 2. Group D G had a higher ratio of medication than group E G and group E H, and this result was statistically significant. 3. Group G had a higher ratio of esophagitis than group H, and this result was statistically significant. 4. A Group B H had a higher ratio of esophagitis than group B G, group C G, and group C H, and this result was statistically significant. 5. The medication group had a high score on the function index than the non-medication group, and this result was statistically significant. Conclusions : This study suggests that there is a slight correlation between gastroscopy results and zone-5 data from the 7-zone-diagnostic system. The research resulted in significant data that are helpful for diagnosing digestive system problems through the use of the 7-zone-diagnostic system.