• 한국진공학회:학술대회논문집
• /
• 한국진공학회 2010년도 제39회 하계학술대회 초록집
• /
• pp.279-279
• /
• 2010

Smart gels have recently associated with photonic crystals to form photonic gels. Since these photonic gels are capable of reversibly converting the volume change of gels induced in response to external chemical or electric stimuli into characteristic optical signals, they have been considered not only as a good platform for label-free chemical or biological detection, actuators or optical switches but also as a good model system to investigate gel swelling behaviour. Recently, we reported block copolymer photonic gels self-assembled from polystyrene-b-poly(2-vinyl pyridine) (PS-b-P2VP) block copolymers, and demonstrated that selective swelling of lamellar structure allows extremely large tunability of the photonic stop band from UV region to IR region ($\lambda$ peak=350~1,600 nm). Herein we report block copolymer photonic gels which exhibit strong tunable optical hysteresis and their applications. As nonlinear responses in swelling of hydrogels were often observed, photonic gels exhibit optical hysteresis with change of external pH. We demonstrate such optical hysteresis can be precisely programmed by controlling ion-pairing affinity. We anticipate that photonic gels with carefully tunned optical hysteresis are applicable to optical memory devices.

• 한국정보통신학회논문지
• /
• 제11권5호
• /
• pp.1019-1028
• /
• 2007

본 논문에서는 적응진화알고리즘을 사용한 퍼지 제어기의 설계방법을 제안하였다. 적응진화알고리즘은 전역탐색특성이 우수한 유전알고리즘과 다음세대를 포함하는 해집단에 대해 적응적으로 우수한 국부탐색특성을 가진 진화전략을 사용한다. 재교배 과정에서 유전알고리즘과 진화전략을 위한 해집단의 분배는 적합도에 따라서 적응적으로 결정된다. 적응진화알고리즘은 퍼지제어기의 설계 파라메터인 퍼지변수에 대한 소속함수와 스케일 요소를 결정하는데 사용된다. 제기된 퍼지제어기의 성능을 평가하기 위해서 비선형 특성을 가진 실제 DC 모터 속도제어 시스템을 구성하여 실험하였으며, 실험결과 PD제어기의 경우보다 우수한 속도 제어성능을 가짐을 확인하였다.

• Smart Structures and Systems
• /
• 제24권6호
• /
• pp.733-744
• /
• 2019

Wind speed forecasting is critical for a variety of engineering tasks, such as wind energy harvesting, scheduling of a wind power system, and dynamic control of structures (e.g., wind turbine, bridge, and building). Wind speed, which has characteristics of random, nonlinear and uncertainty, is difficult to forecast. Nowadays, machine learning approaches (generalized regression neural network (GRNN), back propagation neural network (BPNN), and extreme learning machine (ELM)) are widely used for wind speed forecasting. In this study, two schemes are proposed to improve the forecasting performance of machine learning approaches. One is that optimization algorithms, i.e., cross validation (CV), genetic algorithm (GA), and particle swarm optimization (PSO), are used to automatically find the optimal model parameters. The other is that the combination of different machine learning methods is proposed by finite mixture (FM) method. Specifically, CV-GRNN, GA-BPNN, PSO-ELM belong to optimization algorithm-assisted machine learning approaches, and FM is a hybrid machine learning approach consisting of GRNN, BPNN, and ELM. The effectiveness of these machine learning methods in wind speed forecasting are fully investigated by one-year field monitoring data, and their performance is comprehensively compared.

• 대한조선학회논문집
• /
• 제43권1호
• /
• pp.96-102
• /
• 2006

In this study, an optimization routine with genetic algorithms is coupled for the selection of free variables for the production of a control signal for the motion of wave board in the numerical wave tank. An excitation function for the controlling of the wave board is formulated on basis of amplitude modulation for the generation of nonlinear wave packets. The found variables by the optimization serve for the determination of wave board motion both with the computation and with the experiment. The breaking criterion of the water waves is implemented as boundary condition for the optimization procedure. With the analysis of the time registration on the local position in the wave tank the optimization routine is accomplished until the given design wave with defined surface elevation is found. Water surface elevation and associated fields of velocity and pressure are numerically computed.

• 한국콘텐츠학회논문지
• /
• 제19권2호
• /
• pp.469-476
• /
• 2019

로봇의 움직임은 3차원 공간상의 다관절 좌표계의 회전 및 이송으로 표현된다. 이러한 좌표계 모델링을 위해 동차 변환 행렬의 관계식으로 표현하나 복잡한 3차원 공간상의 움직임을 고려하여 시각화 기법을 이용한 시뮬레이션 환경 기반의 모델링 및 생성한 동작의 확인이 필수적이다. 기존 시뮬레이션 환경의 경우, 플랫폼 의존도가 높으면 정해진 명령어의 수행으로 구성되어 사용성 및 확장의 한계성이 있었다. 본 논문에서는, 웹 기반의 3차원 시뮬레이션 환경을 구축하고, 소형 웹 서버 모듈과 사용성이 용이한 Python 스크립트의 연동 방식을 통해 높은 사용자 접근성을 얻고자 한다. 또한 로봇 제어를 위한 비선형 모델의 적용 사례를 통해 제안된 시스템의 연산 능력, 프로세스 관리 방식의 성능 및 사용자 스크립트 연동을 통한 확장성을 검증하고자 한다.

• Wind and Structures
• /
• 제29권3호
• /
• pp.177-194
• /
• 2019

While establishing adequate load paths in the light-frame wood structures is critical to maintain the overall structural integrity and avoid significant damage under extreme wind events, the understanding of the load paths is limited by the high redundant nature of this building type. The objective of the current study is to evaluate the system effects and investigate the load paths in the wood structures especially the older buildings for a better performance assessment of the existing building stock under high winds, which will provide guidance for building constructions in the future. This is done by developing building models with configurations that are suspicious to induce failure per post damage reconnaissance. The effect of each configuration to the structural integrity is evaluated by the first failure wind speed, amajor indicator beyond the linear to the nonlinear range. A 3D finite-element (FE) building model is adopted as a control case that is modeled using a validated methodology in a highly-detailed fashion where the nonlinearity of connections is explicitly simulated. This model is then altered systematically to analyze the effects of configuration variations in the model such as the gable end sheathing continuity and the gable end truss stiffness, etc. The resolution of the wind loads from scaled wind tunnel tests is also discussed by comparing the effects to wind loads derived from large-scale wind tests.

• 대한건축학회논문집:구조계
• /
• 제36권1호
• /
• pp.137-146
• /
• 2020

In this study, various application schemes of seismic isolation system which can be applied to Hanok have been studied by analyzing its structural characteristics under seismic load. Structural stability of Hanok is more required against seismic load as Hanok becomes long-spanned and multi-storied. To meet this goal, it becomes necessary to study more advanced technology such as seismic isolation design as well as seismic control design and seismic resistant design suitable to Hanok. Seismic isolation systems have been successfully applied to RC and steel structures to improve structural performance during earthquakes. Based on these previous study, we proposed four application schemes of seismic isolation design suitable for Hanok and analyzed their structural characteristics and applicability to Hanok in conceptual level based on its structural characteristics. The proposed four schemes are base isolation method, ground isolation method, roof isolation method and intermediate-story isolation method. The applicability of the proposed method was evaluated by performing boundary nonlinear dynamic analysis to the typical Hanok for the two types of isolation method, that is, ground isolation method and roof isolation method, and the results showed that the proposed methods produced good performance enough to be applied to Hanok.

• 한국전자통신학회논문지
• /
• 제17권5호
• /
• pp.833-840
• /
• 2022

산업 현장에서 자동화 장비 및 모터의 정밀도가 요구되고 있고 전 세계 모터 시장 규모는 많이 증가하였지만, 국내 모터 기술은 해외 기술보다 뒤처져 있다. 본 논문에서는 모터의 기술 향상을 위해 PLC 서보 모터와 아두이노 스텝모터에 비선형 알고리즘을 적용하여 정밀도 안정도, 효율을 선형 알고리즘과 비교하였다. 비선형 알고리즘이 선형 알고리즘에 비해 모터의 최고 속도가 빨라 같은 구동 기준 소요 시간을 단축할 수 있었으며 곡률이 적어 정밀도가 향상되는 것을 확인하였다.

• Earthquakes and Structures
• /
• 제5권6호
• /
• pp.657-678
• /
• 2013

For economical earthquake resistant design of cable-stayed bridge tower, the use of energy dissipation systems for the earthquake protection of steel structures represents an alternative seismic design method where the tower structure could be constructed to dissipate a large amount of earthquake input energy through inelastic deformations in certain positions, which could be easily retrofitted after damage. The design of energy dissipation systems for bridges could be achieved as the result of two conflicting requirements: no damage under serviceability limit state load condition and maximum dissipation under ultimate limit state load condition. A new concept for cable-stayed bridge tower seismic design that incorporates sacrificial link scheme of low yield point steel horizontal beam is introduced to enable the tower frame structure to remain elastic under large seismic excitation. A nonlinear dynamic analysis for the tower model with the proposed energy dissipation systems is carried out and compared to the response obtained for the tower with its original configuration. The improvement in seismic performance of the tower with supplemental passive energy dissipation system has been measured in terms of the reduction achieved in different response quantities. Obtained results show that the proposed energy dissipation system of low yield point steel seismic link could strongly enhance the seismic performance of the tower structure where the tower and the overall bridge demands are significantly reduced. Low yield point steel seismic link effectively reduces the damage of main structural members under earthquake loading as seismic link yield level decreases due their exceptional behavior as well as its ability to undergo early plastic deformations achieving the concentration of inelastic deformation at tower horizontal beam.

• 한국정보과학회논문지:시스템및이론
• /
• 제27권1호
• /
• pp.61-67
• /
• 2000

산업용 실시간 시스템에서 사용되는 디지털 제어기는 상호 작용하는 주기적 태스크들로 이루어져 있다. 이러한 태스크들은 최대 수행 주기 (maximum activation periods)를 제약조건으로 가짐으로써, 요구되는 제어특성을 유지한다. 그러므로 실시간 시스템을 개발하는데 있어 필수적인 단계는 각각의 태스크에 게 자원 이용률을 최소화하면서 최대 수행 조건을 만족시킬 수 있는 고정된 주기를 할당하는 것이다.[1] 각각의 태스크간의 생산자/소비자(producer/consumer)관계를 나타내주는 태스크 그래프와 자원 요구량, 그리고 주기에 대한 범위제한이 주어진다면 주기 할당 문제는 비선형 최적화 문제가 된다. 이 논문에서는 최적해의 자원이용률의 두 배를 넘지 않는 해를 찾을 수 있는 선형 수행시간의 근사 알고리즘을 제시한다. 실험 결과에서 알 수 있듯이, 제안된 알고리즘은 대부분의 경우 최적해에 매우 근접한 해를 가지게 된다.