틸트로터 무인기 로터 발란싱

김유신,이명규,최성욱 한국항공우주학회 2012 한국항공우주학회 학술발표회 논문집 Vol.2012 No.11

제대로 balancing이 잡힌 회전체는 베어링에 크게 무리를 주지 않으며 피로파괴될 확률을 현저히 줄여 주어 회전체 시스템의 수명을 연장해 준다. 틸트로터 형태의 스마트무인기는 동체 중앙에 엔진이 장착되어 있고, 엔진으로부터 발생한 출력은 드라이브시스템을 거쳐 양쪽 날개 끝에 위치한 로터시스템으로 전달된다. 스마트무인기의 로터시스템 balancing을 위하여 각각의 로터에 single plane balancing을 적용하였으나, balancing 작업을 완료한 로터가 반대쪽 로터의 balancing 작업 후에 다시 balancing이 틀어지는 현상이 발생하였다. 이후 2 plane balancing을 적용하여 이러한 cross effect를 해결하였으나, 100% 운용 회전수에서 balancing을 완료한 로터들이 80% 운용 회전수에서 매우 심한 unbalance를 보이는 현상이 다시 나타나, 최종적으로 2 plane multi speed balancing을 적용하여 over balancing 문제를 해결하였다. Balancing of rotors prevents excessive loading of bearings and avoids fatigue failure, thus increasing the useful life of machinery. Smart UAV is a tiltrotor type UAV and equipped with one turbo shaft engine located at the center of fuselage. The output torque from the engine is transferred to the rotors located at the both ends of wing through the drive system. Single plane balancing was applied to each rotor, but the unbalance of balanced rotor was increased after the balancing of the other rotor. This cross effect was resolved by introducing 2 plane balancing, but the rotors balanced at 100% operating rpm experienced significant unbalance at 80% operating rpm. To resolve this problem, 2 plane multi speed balancing was finally introduced and the over balancing problem at one speed was well settled.

Effort of Load Balancer to Achieve Green Cloud Computing : A Review

G.Siva Shanmugam,N.Ch.S. N. Iyengar 보안공학연구지원센터 2016 International Journal of Multimedia and Ubiquitous Vol.11 No.3

In a distributed system, from the starting days onwards distribution of load among servers becomes a serious problem in the commercial Internet. The problem in this scenario is? The entire single application oriented server has to engage the entire amount of traffic and if they went down, all commercial activities come down offline result out of business. Running individually the application server couldn’t support start-up budgets. The folks involved in the Web Commercial plan to solve this problem by distributing the load evenly to all the servers running on the web host owned by different agents or organizations; thus new scenario was born named as Load Balancing. In this treatise, we investigate several shapes attenuated by load Balancer and reviewed the algorithms proposed on load balancing. Here we took both static as well as dynamic based algorithms and their performances are formulated by comparison with all other existing scheme. This paper also brings connectivity on green computing with cloud load balancers. By cloud computing we can attain multi tenancy and dynamic resource handling which automatically reduces co2 emission from servers. Without the facility of sharing single resources among thousands of peoples, green computing is not possible. So the nature of cloud load balancer and green computing was illustrated here.

전기자동차 배터리 팩 SOC 추정 기반 Buck-Boost 능동형 셀 밸런싱

남은택(Euntaek Nam),이세진(Sejin Lee),권용성(Youngsung Kwon) 한국산학기술학회 2023 한국산학기술학회논문지 Vol.24 No.2

배터리 관리 시스템(BMS: Battery Management System)은 전기자동차 배터리 팩 내에 발생하는 에너지 불균형을 개선하기 위해 셀 간의 에너지 밸런싱을 수행한다. 기존의 연구에서 에너지 밸런싱을 위해 주로 사용한 배터리 셀의 단자전압 정보나 미리 맵핑된 배터리 충전상태(SOC: State of Charge)와 개방회로전압(OCV: Open Circuit Voltage)표는 실제 배터리의 충전상태를 반영하지 못하므로 정확한 셀 밸런싱을 수행했다고 보기 어렵다. 본 논문은 확장 칼만 필터(EKF: Extended Kalman Filter) 기반의 SOC 추정을 통해 셀 밸런싱을 수행하고 기존의 전압기반 밸런싱 방법과의 비교분석을 통해 BMS의 효과적인 밸런싱 운용 방법을 제시한다. EKF 기반의 알고리즘 설계를 위한 등가회로 모델링과 단계별 파라미터 추출을 진행했고, SOC 추정 결과는 초기 짧은 구간을 제외한 SOC의 전 구간에서 1 % 미만의 낮은 오차를 보였다. 추정된 SOC 정보를 바탕으로 셀 간의 에너지 밸런싱을 수행하기 위해 벅-부스트 컨버터를 설계했고, 밸런싱 결과는 셀 간의 전압이 균등해지는 시점의 SOC가 3.97 %의 편차를 보임으로써, 밸런싱으로 인한 전압의 균등화와 실제 SOC의 균등화가 다소 차이가 있는 것을 확인했다. 본 논문에서 제안한 EKF 활용 SOC 추정 기반의 셀 밸런싱은 실제 SOC 기반 밸런싱의 분석 및 영향에 기여함으로써 BMS의 배터리 운용의 신뢰성을 향상시킬 것으로 기대된다. A BMS performs energy balancing between cells to reduce energy imbalance that occurs in a battery pack in electric vehicles. In previous studies, terminal voltage information or a pre-mapped SOC-OCV table was mainly used for energy balancing but cannot show accurate cell balancing because balancing was not performed based on an actual batterys charge state. This paper proposes an effective balancing operation method of BMS by performing cell balancing through SOC estimation based on an EKF and a comparative analysis with existing voltage-based balancing methods. Modeling of a batterys equivalent circuit and step-by-step parameter extraction were performed for EKF-based algorithm design, and the SOC estimation results showed low error of less than 1 % in all sections of SOC except for the initial stage. Based on the estimated SOC, a buck-boost converter was designed to perform energy balancing between cells. The balancing result showed that SOC at the time of equalizing voltage between cells had a deviation of 3.97 %, which confirms that equalization of voltage due to balancing is slightly different from equalization of the actual SOC. The method proposed in this paper can improve the reliability of BMS operation by contributing to the analysis and impact of actual SOC-based balancing.

Chopped anodic 펄스 제어를 이용한 charge balanced 뇌신경 자극 집적회로

손진영,차혁규 대한전자공학회 2019 전자공학회논문지 Vol.56 No.9

This paper presents a neural stimulator integrated circuit(IC) using chopped pulse waveform for high power efficiency and charge balancing. The proposed IC is designed using 0.18-μm standard CMOS process and consists of electric stimulation circuit and charge balancing circuit. Transistor stacking and dynamic gate biasing technique are used to protect the output current driver and charge balancing circuit from high voltage stress. The proposed system has flexibility to select two types of stimulation waveform according to the situation. A very simple digital logic circuit consisting of a comparator and D-Latch performs safe charge balancing to prevent the accumulation of residual potential on the electrodes. 이 논문에서는 높은 전력 효율과 charge balancing을 위해 chopped 펄스 파형을 이용하는 신경 자극기 집적 회로(IC)를 제시한다. 제안된 IC는 0.18-μm 표준 CMOS 공정을 사용하여 설계되었으며, 전기 자극 회로와 charge balancing 회로로 구성된다. Transistor stacking 및 Dynamic gate biasing 설계 기술이 고전압 스트레스로부터 전류 출력 드라이버와 charge balancing 회로를 보호하기 위해 사용되었다. 제안된 시스템은 상황에 따라 두 가지 자극 파형을 선택할 수 있도록 하여 유연성을 가지며 비교기와 D-Latch로 구성된 매우 간단한 디지털 논리 회로를 통해 안전한 charge balancing을 수행하여 전극의 잔류 전위 축적을 방지한다.

미중 전략경쟁과 베트남의 대중국 전략: 헤징에서 연성균형 전략으로

조원득 ( Wondeuk Cho ),이상숙 ( Sang-sook Lee ) 조선대학교 동북아연구소(구 통일문제연구소) 2020 동북아연구 Vol.35 No.2

연구는 베트남의 위협인식 변화에 따른 베트남의 대중국 전략이 헤징에서 연성균형으로 변화했음을 설명하였다. 역사적으로 대중국 위협 인식이 높은 베트남은 1979년 중국과의 전쟁 이후 중국과 국교를 단절하였다가, 탈냉전 이후 1991년 중국, 1995년 미국과 차례로 국교를 정상화하면서 대중국 헤징 전략을 취하였다. 베트남의 대중국 위협인식이 높아지면 베트남은 헤징에서 균형 방향으로 전략을 이동하게 되는데, 이 경우 중국에 대한 경제적 의존과 국력의 비대칭성을 고려하여 제 3국과의 동맹을 기반으로 하는 경성균형이 아닌 연성균형을 선택하게 된다. 먼저 베트남은 해양방위 역량의 약세 등 대중국 군사력 비대칭성과 경제적 의존으로 인해 비군사적 연성균형 전략을 추진하였다. 베트남은 중국의 공세적 베트남 영유권 침해에 대한 항의 성명발표와 유엔 등 국제기구 및 국제사회에서 중국의 불법 행위 공론화 등으로 중국의 입지를 약화하는 비군사적 연성균형 전략을 추구하였다. 그러나 남중국해에서 중국의 공세적군사 행동이 증가함에 따라 군사적 연성균형 전략을 추구하기 시작하였다. 무엇보다도 베트남은 미국과의 연합 군사훈련 실시, 베트남군의 미국 내 훈련 프로그램 참여, 미국해양 경비정의 인수 등의 방법으로 해양방위 역량을 강화하고 있다. 동시에 베트남은 일본, 호주, 인도 등 쿼드 국가(4개국 안보협력체)들과의 군사안보 협력도 확대하고 있다. 이러한 측면에서 본 연구는 남중국해에서 벌어지고 있는 미중 전략경쟁과 베트남의 대중국 위협인식 변화를 반영하여 베트남의 대중국 전략이 헤징에서 연성균형으로, 특히 비군사적 연성균형에 군사적 연성균형으로 이동하였음을 분석하였다. This study explains the change in Vietnam’s strategy toward China in response to the change of its threat-perceptions to China, from ‘hedging’ to ‘balancing,’ with regard to a continuous policy spectrum. Vietnam, which has historically been highly aware of China’s threats, severed its relationship with China after the war against China in 1979. But Vietnam normalized its diplomatic relations with China in 1991 due to the Sino-Russian rapprochement after the post-Cold War. It adopted a hedging strategy toward China since the normalization with the US. When Vietnam’s threat perceptions to China has deepened, Vietnam adopted a balancing strategy instead of a hedging. In this case, it considered the economic interdependence with China and Sino-Vietnam power asymmetry, and therefore, selected a soft balancing rather than a hard balancing. Vietnam announced a statement in protest against China’s assertive behaviors and violation of Vietnam’s sovereignty. In addition, Vietnam appeals to international institutions such as the United Nations and international community about China’s illegal activities in order to internationalize the South China Sea disputes, to weaken China’s position and to gain support from other countries. However, As China’s revisionist and offensive military activities in the South China Sea have not been suppressed, but rather increased, Vietnam began to change its strategy to military soft balancing strategy. Above all, Vietnam is strengthening its maritime defense capabilities by increasing its defense and security cooperation with the United States, including joint exercises, military training, and transfer of US patrol boats to Vietnam’s coast guards. At the same time, Vietnam is expanding its military security cooperation US security partners(so-called Quad countries) including Australia, India, and Japan. In this respect, this study analyzes that Vietnam is changing its strategy from hedging strategy to soft balancing, and especially strengthening military soft balancing in addition to non-military soft balancing, reflecting changes in the international political environment and Vietnamese perception of threat to China in the South China Sea.

Discrete optimization of rigid rotor balancing

Tanguy Messager,Mariusz Pyrz 대한기계학회 2013 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.27 No.8

This work deals with the discrete optimization problem of rotor two-plane balancing. The best balancing configuration is searched for two discrete parameters: allowed standard masses and predefined angular positions on the balancing planes. The objective is to minimize the residual unbalancing effects (such as reactions in supports) thanks to an optimal location of several accurately selected masses on each balancing plane. The corresponding optimization problem is solved using genetic algorithm. A simple model of a rigid rotor mounted on rigid supports is investigated in numerical examples. The optimization efficiency and the influence of the number of applied balancing masses are discussed. The experimental tests have validated the developed balancing approach.

일체형 삼점지지 고압 LNG 2차 펌프 rotor의 1차 mode 특성을 고려한 Balancing 벡터선도 연구

최병근(Byeong Keun Choi),박선휘(Sun Hwi Park),하정민(Jeong Min Ha),김효중(Hyo Jung Kim),김학은(Hack Eun Kim) 한국소음진동공학회 2016 한국소음진동공학회 학술대회논문집 Vol.2016 No.4

Balancing of rotating machinery can determines the life of the machine. before further damage occurs. The subject of this paper is a secondary high-pressure LNG Pump. This pump has a long shaft and integral type of rotor. Also, the shaft has three support points. This shape has difficulty correcting the unbalance using the existing two-plane balancing. Therefore balancing technology development is required. It simulated a high-pressure LNG Pump with Rotor and Shaft shape of the subject integrated using Pilot Rotor as previous studies to determine the optimal balancing rpm of the Lab Scale Shaft. By carrying out balancing at each rpm, we compared the amplitude, drew the graph and compared every aspect resulted from balancing at each rpm. Then, we check which rpm the most advantageous balancing occurs at.

논문 : 조공제도에서의 세력균형 정치

김진웅 ( Jin Wung Kim ) 역사교육학회 2015 역사교육논집 Vol.57 No.-

This study seeks to answer the two following questions. First, did balance-of-power politics constitute an inherent attribute of the pre-modern East Asian tribute system? Second, how did balance-of-power politics manifest itself in tributary interstate relations in historical East Asia? The main observations can be summed up as follows. Balance-of-power politics has been the order of the anarchic and uncertain international system. As in other international systems employed in other places at other times, China and its tributaries were surely involved in power politics to promote their own interests, specifically for the sake of survival, under the tribute system. In particular, they actively conducted balance-of-power politics against each other. In the course of struggling for survival, China and specifically its neighbors pursued balancing as their foreign policy. When the balancing strategy fell short of their expectations, China’s neighbors had no hesitation in employing the bandwagoning strategy. As in many other international systems, several Chinese dynasties and their neighboring polities forged alliances with each other. To make the most use of China’s division, some tributaries played off one Chinese empire against another. When two rival empires contended against each other in China proper, some pursued a balanced, neutral policy to jump on the victor’s bandwagon in the long run. Also, many climbed on China’s bandwagon to ward off its possible invasion. These different balancing and/or bandwagoning strategies were performed individually or two or more combined. Finally, in complex balance-of-power games under the tribute system, the East Asian political entities as a whole employed China’s traditional diplomatic strategy of “befriending distant states and of conflicting with neighbors.”

가속도를 입력으로 갖는 모델을 이용한 Balancing Robot의 균형제어기 구현

최정윤,이영삼 제어·로봇·시스템학회 2018 제어·로봇·시스템학회 논문지 Vol.24 No.1

In this paper, we derive a new type of mathematical model for a two-wheeled balancing robot and propose a controller implementation method based on the model. In the newly derived model, the acceleration of the robot body is used as the control input for the system, which provides the advantage of flexible selection of motors used for driving the robot. First, using Lagrangian dynamics and variable elimination, we derive a new type of mathematical model in which the acceleration of the robot body is the input to the balancing robot. Second, we propose a balancing control method based on the newly derived model. The structure of the controller adopts the LQR (Linear Quadratic Regulator) to determine the acceleration required for balancing. The obtained acceleration is converted to the velocity references of two wheels through integration and transformation. The resultant velocity references are followed through PI-type velocity controllers. Third, the implementation of the controller and the experimental results are presented. Two balancing robots are built, one of which adopts DC motors while the other uses step motors for actuation. Control experiments are conducted to verify the effectiveness of the proposed model and control method. The experimental results are illustrated through a phase portrait and the pitch angle of the robot and the control performance is analyzed. The proposed model and control method do not require the electrical coefficients of the adopted motor, thus offering great flexibility in motor selection.

연삭기용 자동 밸런싱 장치의 설계 및 평가

장홍석,최대봉,황주호,홍준희 한국공작기계학회 2001 한국공작기계학회 춘계학술대회논문집 Vol.2001 No.-

The balance of high speed spindle system with high precision rotation like grinding machine is very important. Traditionally, we use trial and error method to balance the spindle. It takes much time. So we are developing the automatic balancing equipment being used in the grinding machine. The balancing head we develop is wireless. It will be used high-speed grinding machine. We use influence coefficient method to control the automatic balancer. Experiments are based on automatic and manual balancing. We perform test of the vibration filter. It helps to remove noise. The filter and experiments with automatic balancing controller show that automatic balancing control can be successfully achieved with the quick response and good stability characteristics.