• 한국시스템다이내믹스연구
• /
• 제12권4호
• /
• pp.35-62
• /
• 2011

PFI(Private Finance Initiative) for suppling SOC and public facilities instead of Government Infrastructure Project introduced from 1994. BTO(Build-Transfer-Operate) project had been major type of PFI system from 1994 to 2005. But after changed the Law of PFI on SOC, the BTL project newly introduced. In BTO system, the Government retrieves the investment through the operating income, but in BTL system, the government lease the facilities. As the BTO and BTL projects are widely adopted and implemented to ease the fiscal burden of government, but it has caused the tremendous fiscal burden each year over the period operation. Therefore this study attempted to analyze the question, that is, why government fiscal burden tipping? Hence, this paper, compares the difference of business structure between BTO and BTL project and explore the vicious and virtuous business structure, with the method of circular causal loop analysis. As a result, it has shown that there are some positive feedback and negative feedback loops cause the tipping and easing of government fiscal burden.

• Wind and Structures
• /
• 제17권3호
• /
• pp.263-274
• /
• 2013

A numerical technique for fluid-structure interaction, which is based on the finite element method (FEM) and computational fluid dynamics (CFD), was developed for application to an industrial chimney equipped with a pendulum tuned mass damper (TMD). In order to solve the structural problem, a one-dimensional beam model (Navier-Bernoulli) was considered and, for the dynamical problem, the standard second-order Newmark method was used. Navier-Stokes equations for incompressible flow are solved in several horizontal planes to determine the pressure in the boundary of the corresponding cross-section of the chimney. Forces per unit length were obtained by integrating the pressure and are introduced in the structure using standard FEM interpolation techniques. For the fluid problem, a fractional step scheme based on a second order pressure splitting has been used. In each fluid plane, the displacements have been taken into account considering an Arbitrary Lagrangian Eulerian approach. The stabilization of convection and diffusion terms is achieved by means of quasi-static orthogonal subscales. For each period of time, the fluid problem was solved and the geometry of the mesh of each fluid plane is updated according to the structure displacements. Using this technique, along-wind and across-wind effects have been properly explained. The method was applied to an industrial chimney in three scenarios (with or without TMD and for different damping values) and for two wind speeds, showing different responses.

• Smart Structures and Systems
• /
• 제7권2호
• /
• pp.103-116
• /
• 2011

This paper is concerned with the trajectory tracking and vibration suppression of a single-link flexible arm by using piezoelectric materials. The dynamics of a single flexible arm with PZT patches as sensor and actuator is derived using extended Hamilton's principle. Resulting equations show that the coupled beam dynamics including beam vibration and its rigid in-plane rotation takes place in two different time scales. By using singular perturbation theory, the system dynamics is divided into two subsystems. Then, a composite control scheme is elaborated that makes the orientation of the arm track a desired trajectory while suppressing its vibration. The proposed controller has two parts: one is a tracking controller designed for the slow (rigid) subsystem, and the other one is a stabilizing controller for the fast (flexible) subsystem. The outputs considered for the system are angular position of the hub and voltage of the sensor mounted on the structure. To avoid requiring further measurements of beam vibration and also angular velocity of the hub for the fast and slow control laws, respectively, two sliding mode observers for estimating the unknown states are also designed.

• 한국시스템다이내믹스연구
• /
• 제7권1호
• /
• pp.5-26
• /
• 2006

Ever increasing dependence of organization on information technology stimulates interactions between individuals and groups in the process of knowledge creation, which overall impies that a reciprocal mechanism lies within the structure of the growth of group intelligence. Individual's intelligence may affect the group intelligence, and vise versa. However, the level of group intelligence is not necessarily determined by the sum of individual's intelligence but the quality of the interactions among the individuals. This study thus aims to conceptually identify the dynamic structure of interactions among the factors influencing the group intelligence level, which is believed to be used as a tool to measure the difference of intelligence between groups. To achieve this goal several attempts were made. First, determinants of intelligence at indiviual level and group level and similarities and differences between individual's and group intelligence were identified from the previous research. Second, causal loop diagrams were developed, which show how individual's intelligence influences group intelligence and vise versa. Third, it was attempted to identify and interpret which feedback loops are most influential in either improving or hapering group intelligence as a whole. Since this study remains only at exploratory level, a more detailed and workable model for field applications has to be developed in the future.

• 정보과학회 컴퓨팅의 실제 논문지
• /
• 제21권4호
• /
• pp.338-342
• /
• 2015

시계열 데이터를 다룰 수 있는 기계학습모델인 회귀 신경망은 되먹임 연결을 허용하기 때문에 앞먹임 신경망에 비해 훨씬 다양한 구조를 가질 수 있다. 본 연구에서는 은닉 뉴런 간의 네트워크 구조에 초점을 맞추어 그것이 회귀 신경망의 정보처리 능력에 미치는 영향을 탐구하고자 한다. 이를 위해 회귀신경망 모델 중 하나인 Echo State Network을 기준으로 하여, 여러 가지 잘 알려진 네트워크 모델에 따라 은닉 뉴런 간 연결을 구성하고 각각의 경우에 시계열 학습 능력과 동역학을 분석하였다. 그 결과, 은닉 뉴런의 네트워크 구조에 따라 모델의 성능이 큰 폭으로 변하는 것이 관찰되었으며, 그러한 현상은 신경망 동역학이 가지는 임계도(criticality)의 변화와 잘 일치했다. 본 연구의 결과는 기존 회귀 신경망 연구에서 주된 관심사였던 신경망 연결 가중치뿐만 아니라 신경망의 연결 구조가 모델의 성능에 중요한 영향을 미친다는 사실을 보여주며, 성능 향상을 위한 중요한 단서가 될 수 있다.

• BMB Reports
• /
• 제40권2호
• /
• pp.261-269
• /
• 2007

The structure and dynamics of a 37-residue antimicrobial peptide gaegurin 4 (GGN4) isolated from the skin of the native Korean frog, Rana rugosa, was determined in SDS micelles by NMR spectroscopy. The solution structure of the peptide in SDS micelles was determined from 352 NOE-derived distance constraints and 22 backbone torsion angle constraints. Dynamic properties for the amide backbone were characterized by $^1H-^{15}N $heteronuclear NOE experiments. The structural study revealed two amphipathic helices spanning residues 2-10 and 16-32 and that the helices were connected by a flexible loop. An intraresidue disulfide bridge was formed between residues Cys31 and Cys37 near the C-terminus. The loop region (11-15) connecting the two helices are were slightly more flexible than these helices themselves. From the fact that since there is no contact NOEs between two helices, it is implied that the GGN4 peptide shows an independent motion of both helices which has an angle of about $ 60^{\circ}-120^{\circ}$ from each other.

• 한국시스템다이내믹스연구
• /
• 제16권3호
• /
• pp.49-75
• /
• 2015

A company is a core of free market capitalism. It needs to be sustainable to make capitalism better. In this reason, a company has to be ethical to be longer, because unethical company can not be survival. It means that we should understand what is the ethical company and how to be. Because interdisciplinary exchanges give a hint to understand what and how from, so it was studied to find the academic theories which have a relationship with ethics or morality not only in the area of Business management, but also Psychology, Pedagogy, Ethics, Philosophy, and etc.. Making a visible structure by System Dynamics with results through interdisciplinary exchanges to understand the reason why unethical accidences are rising and damages are growing although companies pay "Ethics Pays" more and more to reduce immoral cases is the goal of this study. On the theory of "Social Ethics", 5 ways explain the reason why unethical behavior has not been demolished make a complex structure, which was founded from studying interdisciplinary exchanges such as "Ethics Pays", "Moral Reasoning", "Social Cost", and "Fallacy of Compositions". Finding the controllers and Factors of this model to control to be better, then the market could be more effective with lesser social cost.

• 한국정보시스템학회지:정보시스템연구
• /
• 제15권4호
• /
• pp.99-124
• /
• 2006

The development of IT has made it possible to use various terminal systems for financial transaction and demands for financial survices are getting more and more diversified at the same time. Among others, mobile banking service market based on IC chips has been expanded its service areas and the number of mobile banking users has been increased. The study analyzes and tests the dynamic effects of the inflow of potential customers on mobile banking market condition by using system dynamics methodology to identify the dynamic structure of mobile banking market. The simulation model is designed to track the variation in the number of subscribers of mobile banking servides according to two scenarios, and the results are as follows; First the effect of word of mouth by customers who have used the service already is significant. The satisfactory level of early adopters is reflected in WOM, and as a test result shows, increase in word-of-mouth causes the growth of potential customers' demands for mobile banking service. Second, perceived attractiveness of mobile banking service market is another important construct. Factors such as convenience, mobility, time saving, security, and various services explain the construct perceived attractiveness of the service, and it makes the potential customers adopt the service, causing the increase of demands.

• Wind and Structures
• /
• 제16권5호
• /
• pp.411-431
• /
• 2013

A computational study of vortex-induced transverse vibrations of a cylinder with low mass-damping is presented. An Arbitrary Lagrangian-Eulerian (ALE) formulation of the Unsteady Reynolds-Averaged Navier-Stokes equations (URANS), along with the Spalart-Allmaras (SA) one-equation turbulence model, are coupled conservatively with rigid body motion equations of the cylinder mounted on elastic supports in order to study the amplitude and frequency response of a freely vibrating cylinder, its flow-induced motion, Vortex Street, near-wake flow structure, and unsteady loading in a moderate range of Reynolds numbers. The time accurate response of the cylinder from rest to its limit cycle is studied to explore the effects of Reynolds number on the start of large displacements, motion amplitude, and frequency. The computational results are compared with published physical experiments and numerical studies. The maximum amplitudes of displacements computed for various Reynolds numbers are smaller than the experimental values; however, the overall agreement of the results is quite satisfactory, and the upper branch of the limit-cycle displacement amplitude vs. reduced velocity response is captured, a feature that was missed by other studies. Vortex shedding modes, lock-in phenomena, frequency response, and phase angles are also in agreement with experiments.

• 한국군사과학기술학회지
• /
• 제12권6호
• /
• pp.704-710
• /
• 2009

In this study, a comparison study of flutter analysis for the AGARD 445.6 wing with wind turnnel test data has been conducted in the subsonic, transonic and supersonic flow regions. Nonlinear aeroelastic using FSIPRO3D which is a generalized user-friendly fluid-structure analyses have been conducted for a 3D wing configuration considering shockwave and turbulent viscosity effects. The developed fluid-structure coupled analysis system is applied for aeroelastic computations combining computational structure dynamics(CSD), finite element method(FEM) and computations fluid dynamics(CFD) in the time domain. MSC/NASTRAN is used for the vibration analysis of a wing model, and then the result is applied to the FSIPRO3D module. the results for dynamic aeroelastic response using different turbulent models are presented for several Mach numbers. Calculated flutter boundary are compared with the wind-tunnel experimental and the results show very good agreements.