• 수산경영론집
• /
• 제25권2호
• /
• pp.89-102
• /
• 1994

This paper is to survey the major results of the game-theoretic models and recent research directions of the literature on auctions and competitive biddings. This paper classifies the auctions and competitive biddings into the following four major types:(i) English auction, (ii) Dutch auction, (iii) the first-price sealed-bid auction, (iv) the second-price sealed-bid auction. In order to survey the major ideas related to auctions and competitive biddings, we use two representative theoretical models developed under the game-theoretic framework : (i) the independent private value model are summarized as follows ; (1) The Dutch auction and the first-price auction are strategically equivalent, and so are the English auction and the second-price auction. (2) At the symmetric equilibria, the expected selling price is the same for all four types of auction. Meanwhile, the major results of the general model are as follows ; (1) When bidders are uncertain about their value extimate, the English and second-price auctions are not equivalent, but the dutch and the first-price auctions are still strategically equivalent. (2) The English auction generates the higher expected prices than the second-price auction. Also, when bidders are risk-neutral, the second-price auction generated higher average prices than the Dutch and the first-price auctions.

• 한국지구과학회지
• /
• 제29권5호
• /
• pp.419-427
• /
• 2008

The Galactic planetary nebulae emit many strong recombination and forbidden lines. By analyzing such lines, the physical condition of the planetary nebulae has been inferred using the strategically important diagnostic line ratios. In order to fully understand the physical condition of a planetary nebula and to derive its chemical abundances, the photoionization model codes, e.g., CLOUDY and NEBULA, were employed for an analysis of gaseous nebular spectra. For the well-studied, relatively simple planetary nebula NGC 7026, theoretical investigation was done with about the same input parameters in models. The predictions made by both codes seem to be in good accord. However, the predicted physical conditions, such as electron temperature and density, are slightly different. Especially, the electron temperatures are predicted to be higher in CLOUDY, which may cause a problem in chemical abundance determination. Our analysis shows that the main discordance may occur due to the diffuse radiation.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• 제14권4호
• /
• pp.1796-1816
• /
• 2020

The health and safety of elderly and disabled patients who cannot live alone is an important issue. Timely detection of sudden events is necessary to protect these people, and anomaly detection in smart homes is an efficient approach to extracting such information. In the real world, there is a causal relationship between an occupant's behaviour and the order in which appliances are used in the home. Bayesian networks are appropriate tools for assessing the probability of an effect due to the occurrence of its causes, and vice versa. This paper defines different subsets of random variables on the basis of sensory data from a smart home, and it presents an anomaly detection system based on various models of Bayesian networks and drawing upon these variables. We examine different models to obtain the best network, one that has higher assessment scores and a smaller size. Experimental evaluations of real datasets show the effectiveness of the proposed method.

• 동력기계공학회지
• /
• 제18권1호
• /
• pp.14-21
• /
• 2014

Piezoelectric fans are thin elastic beams whose vibratory motion is actuated by means of a piezoelectric material bonded to the beam. These fans have found use as a means to enhance convective heat transfer while requiring only small amounts of power. This study presents new types of models with heat sink having air passage and investigates experimentally their heat transfer characteristics. From the comparison results for four models, the heat transfer coefficients of model 1 are approximately 44~66% higher than those of the reference model 0. The model 1 show the best overall performance about heat transfer and cooling capability. As shown in above results, it is necessary to design the heat sink with air pass for cooling of electronic devices, in order to increase the convective heat transfer coefficient of a piezoelectric fan for electronic cooling.

• Structural Engineering and Mechanics
• /
• 제4권6호
• /
• pp.601-612
• /
• 1996

To simulate the large-scale failure evolution with current computational facilities, a simple approach, that catches the essential feature of failure mechanisms, must be available so that the routine use of failure analysis is feasible. Based on the previous research results, a simple analysis procedure is described in this paper for failure simulation. In this procedure, the evolution of localization is represented by a moving surface of discontinuity, and the transition between continuous and discontinuous failure modes are described via the moving jump forms of conservation laws. As a result, local plasticity and damage models, that are formulated based on thermodynamic restrictions, are still valid without invoking higher order terms, and simple integration schemes can be designed for the rate forms of constitutive models. To resolve localized large deformations and subsequent cracking, an efficient structural solution scheme is given for Static and dynamic problems.

• 한국해안·해양공학회논문집
• /
• 제20권3호
• /
• pp.277-290
• /
• 2008

경도 $14^{\circ}$ 범위보다 넓은 구역에 대한 UTM 좌표변환을 위하여 12차 Taylor 전개에 의한 새로운 변환식을 유도하였고 이는 Thomas(1952)의 식을 확장한 것임을 보였다. WGS84와 UTM 좌표의 상호변환에 대한 계산 결과를 나타내었고 차수에 따른 수렴의 정도도 분석하였다. 본 변환식은 우리나라 주변의 조석 또는 지진해일과 같은 장주기 파랑의 전파를 위한 수치모형의 직교좌표 격자구성에 사용될 수 있다.

• Smart Structures and Systems
• /
• 제13권4호
• /
• pp.637-657
• /
• 2014

This paper presents a dynamic analysis of three-dimensional beams. Structures made of functionally graded materials are considered. Several higher-order as well as classical theories are derived by means of a compact notation for the a-priori expansion order of the displacement field over the beam cross-section. The governing differential equations and boundary conditions are obtained in a condensed nuclear form that does not depend on the kinematic hypotheses. The problem is, then, exactly solved in space by means of a Navier-type solution, whereas time integration is performed by means of Newmark's solution scheme. Slender and short simply supported beams are investigated. Results are validated towards three-dimensional FEM results obtained via the commercial software ANSYS. Numerical investigations show that good accuracy can be obtained through the proposed formulation provided that the appropriate expansion order is considered.

• 한국자동차공학회논문집
• /
• 제5권6호
• /
• pp.192-201
• /
• 1997

The feedback control scheme of the pressure control system of the rear wheel steering gear which has relatively large volume and sprung load was built up in order to improve th response characteristic of the system. The control algorithm chosen was a feedback compensator joined by a feedfoward compensator and the model matching method was used in the process of control system design. The structures and properties of the reference models were inspected and the parameters of the controller were decided. The improvement of the response characteristic of the pressure control valve by means of the feedback control is affirmed. Particularly, when the order of the system model is higher than the 2nd order, the effectiveness of the feedback control on the improvement of the response characteristic of the valve is distinct. And the convenience of the model matching method is the process of control system design is confirmed as well.

• Steel and Composite Structures
• /
• 제35권4호
• /
• pp.567-578
• /
• 2020

Based on third-order shear deformation shell theory, the present paper investigates post-buckling properties of eccentrically stiffened metal foam curved shells/panels having initial geometric imperfectness. Metal foam is considered as porous material with uniform and non-uniform models. The single-curve porous shell is subjected to in-plane compressive loads leading to post-critical stability in nonlinear regime. Via an analytical trend and employing Airy stress function, the nonlinear governing equations have been solved for calculating the post-buckling loads of stiffened geometrically imperfect metal foam curved shell. New findings display the emphasis of porosity distributions, geometrical imperfectness, foundation factors, stiffeners and geometrical parameters on post-buckling properties of porous curved shells/panels.

• Advances in nano research
• /
• 제7권4호
• /
• pp.265-275
• /
• 2019

In this work, the effect of size on the axial buckling behavior of single-layered graphene sheets embedded in elastic media is studied. We incorporate Eringen's nonlocal elasticity equations into three plate theories of first order shear deformation theory, higher order shear deformation theory, and classical plate theory. The surrounding elastic media are simulated using Pasternak and Winkler foundation models and their differences are evaluated. The results obtained from different nonlocal plate theories include the values of Winkler and Pasternak modulus parameters, mode numbers, nonlocal parameter, and side lengths of square SLGSs. We show here that axial buckling behavior strongly depends on modulus and nonlocal parameters, which have different values for different mode numbers and side lengths. In addition, we show that in different nonlocal plate theories, nonlocality is more influential in first order shear deformation theory, especially in certain range of nonlocal parameters.