제3국의 지원을 고려한 군사분쟁

박성훈 한국산업경제학회 2023 산업경제연구 Vol.36 No.2

It is witnessed that third countries directly or indirectly participate in military conflicts. This study analyzes the impact of 'substantial' military capabilities, including the support from a third country, on the strategic actions of the parties to the conflict. In particular, it will be investigated whether support from the third country increases rent dissipation. To this end, this study uses a winner-take-all contest model to induce the equilibrium level of force of the countries, the equilibrium probability of wining, the equilibrium expected payoffs, and the rent dissipation arising from the military conflict. Next, this study looks at how changes in 'substantial' military capabilities affect the level of force, the probability of winning, the expected payoffs, and the rent dissipation. The main results of this study are as follows. First, a country with a relatively high 'substantial' military capability becomes the favorite with a low level of force, and that country obtains higher expected payoff than its opponent. Second, support from the third country can reduce the level of force of both countries, and the condition must be that the country receiving support has a significantly higher chance of winning. Third, in order for support from the third country to reduce rent dissipation, the party that is supported must become the favorite. The implications of this study are as follows. The support from a third country affects can reduce rent dissipation. This result shows that support from third countries can reduce the waste of social resources. 군사 분쟁에 제3국이 직간접적으로 참여하는 경우가 목격된다. 본 연구는 제3국의 지원을 포함한 ‘실질적’ 군사능력이 (i) 분쟁 당사국의 전략적 행위에 미치는 영향, (ii) 분쟁으로부터 발생하는 사회적 자원낭비를 증가시키는지 조사하게 된다. 이를 위해 본 연구는 승자독식 게임 모형을 이용하여, 기대이익 극대화 문제에서 당사국들의 균형 무력 수준, 균형 승전확률, 균형 기대이익, 그리고 지대소진(사회적 자원낭비)을 유도한다. 다음으로 ‘실질적’ 군사능력의 변화가 무력수준, 승전확률, 기대익, 그리고 지대소진에 어떤 효과를 주는지 알아본다. 본 연구의 주요 결과는 다음과 같다. 첫째, ‘실질적’ 군사능력이 상대적으로 높은 당사국은 낮은 무력 수준으로 우세국이 되며, 그 당사국은 경쟁국보다 더 높은 기대이익을 얻는다. 둘째, 제3국의 지원 증가는 당사국의 무력수준을 모두 감소시킬 수 있으며, 그 조건은 지원받는 당사국의 승전확률이 월등히 높아야 한다. 셋째, 제3국의 지원이 지대소진을 낮출 수 있으며, 이를 위해서는 당사국이 우세국이 되어야 한다. 본 연구의 시사점은 다음과 같다. 제3국의 지원은 지대소진을 감소시킬 수 있다. 이 결과는제3국의 지원이 사회적 자원낭비를 감소시킬 수 있음을 보이는 것이다.

Towards optimal slip force and stiffness distribution in designing friction dampers

Pourya Sam-Daliri,Seyed Mehdi Zahrai,Hamid Dahaghin 국제구조공학회 2021 Structural Engineering and Mechanics, An Int'l Jou Vol.79 No.3

The considerable capacity of friction dampers in energy dissipation makes them a good choice for vibration control of structures. The slip force of friction dampers and also the stiffness of the corresponding bracing system are the major parameters that must be chosen carefully in the design procedure of these dampers. This paper presents an innovative approach to determine these parameters using the data extracted from a series of analyses conducted on three different structures, subjected to five different earthquake records. For this purpose, 900 time-history analyses are conducted. The responses extracted from these analyses are used to compare the effect of different slip forces and to choose the optimum case. Also, a stiffness calibration method is proposed to determine the bracing system stiffness. Finally, two multi-functional optimization methods are introduced to find a single value for optimal slip force. It is shown that between 56 to 74% of the input energy can be dissipated by friction dampers, using this design approach. Additionally, up to 20, 45, 64, and 62% reductions in maximum displacement, velocity, acceleration, and base shear are achieved respectively for the structures studied in this research.

Steel dual-ring dampers: Micro-finite element modelling and validation of cyclic behavior

Mahdi Usefvand,Ali Mohammad Rousta,Mojtaba Gorji Azandariani,Hamid Abdolmaleki 국제구조공학회 2021 Smart Structures and Systems, An International Jou Vol.28 No.4

Extensive studies have been performed by researchers to increase the ductility and energy-absorption of concentrically braced frames. One of the most widely used strategies for increasing ductility and energy-absorbing is the utilization of energy-dissipation systems. In this regard, the energy-dissipation system consisting of a steel dual-ring damper (SDRD) with different construction details is presented, to improve hysteresis behavior and performance of steel ring dampers (SRD). The most important cause of energy-dissipation in SRDs are the development of bending plastic hinges in the rings. Therefore, by adding an inner ring to the SDR system, it increases the number of moment plastic hinges and in turn increases energy dissipation. Parametric studies havse been performed applying the nonlinear micro-finite element (MFE) procedure to investigate the improved models. The parametric studies comprise examining the efficacy of thickness parameters and the inner ring diameters of the improved models. The SRD models was selected as the base model for comparing and evaluating the effects of improved dampers. MFE models were then analyzed under cyclic loading and nonlinear static methods. Confirmation of the results of the MFE models were performed against the test results. The results indicated that the diameter to the thickness ratio of inner ring of SDRDs has a considerable influence on determining the hysteresis behavior, ductility, ultimate capacity and performance, as well as energy dissipation. Also, the results show that the details of the construction of the internal and external ring connections were a considerable effect on the performance and hysteresis behavior of SDRDs.

Experimentally validated FEA models of HF2V damage free steel connections for use in full structural analyses

Jonathan Desombre,Geoffrey W. Rodgers,Gregory A. MacRae,Timon Rabczuk,Rajesh P. Dhakal,J. Geoffrey Chase 국제구조공학회 2011 Structural Engineering and Mechanics, An Int'l Jou Vol.37 No.4

The aim of this research is to model the behaviour of recently developed high force to volume (HF2V) passive energy dissipation devices using a simple finite element (FE) model. Thus, the end result will be suitable for use in a standard FE code to enable computationally fast and efficient analysis and design. Two models are developed. First, a detailed axial model that models an experimental setup is created to validate the approach versus experimental results. Second, a computationally and geometrically simpler equivalent rotational hinge element model is presented. Both models are created in ABAQUS, a standard nonlinear FE code. The elastic, plastic and damping properties of the elements used to model the HF2V devices are based on results from a series of quasi-static force-displacement loops and velocity based tests of these HF2V devices. Comparison of the FE model results with the experimental results from a half scale steel beam-column sub-assembly are within 10% error. The rotational model matches the output of the more complex and computationally expensive axial element model. The simpler model will allow computationally efficient non-linear analysis of large structures with many degrees of freedom, while the more complex and physically accurate axial model will allow detailed analysis of joint connection architecture. Their high correlation to experimental results helps better guarantee the fidelity of the results of such investigations.

Experimentally validated FEA models of HF2V damage free steel connections for use in full structural analyses

Desombre, Jonathan,Rodgers, Geoffrey W.,MacRae, Gregory A.,Rabczuk, Timon,Dhakal, Rajesh P.,Chase, J. Geoffrey Techno-Press 2011 Structural Engineering and Mechanics, An Int'l Jou Vol.37 No.4

The aim of this research is to model the behaviour of recently developed high force to volume (HF2V) passive energy dissipation devices using a simple finite element (FE) model. Thus, the end result will be suitable for use in a standard FE code to enable computationally fast and efficient analysis and design. Two models are developed. First, a detailed axial model that models an experimental setup is created to validate the approach versus experimental results. Second, a computationally and geometrically simpler equivalent rotational hinge element model is presented. Both models are created in ABAQUS, a standard nonlinear FE code. The elastic, plastic and damping properties of the elements used to model the HF2V devices are based on results from a series of quasi-static force-displacement loops and velocity based tests of these HF2V devices. Comparison of the FE model results with the experimental results from a half scale steel beam-column sub-assembly are within 10% error. The rotational model matches the output of the more complex and computationally expensive axial element model. The simpler model will allow computationally efficient non-linear analysis of large structures with many degrees of freedom, while the more complex and physically accurate axial model will allow detailed analysis of joint connection architecture. Their high correlation to experimental results helps better guarantee the fidelity of the results of such investigations.

The finite element analysis of machining characteristics of titanium alloy in ultrasonic vibration assisted machining

Dexiong Chen,Jinguo Chen,Huasen Zhou 대한기계학회 2021 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.35 No.8

Titanium alloy Ti6Al4V, an alpha-beta alloy, possesses many advantageous properties, such as high special strength, good resilience and resistance to high temperature and corrosion, fracture resistant characteristics and so on, being widely used in aerospace, biomedical and chemical industry. However, its machinability is still a challenge due to its low thermal conductivity, low elastic modulus and high chemical reactivity. As a novel and effective machining method, ultrasonic vibration assisted machining (UVAM) can effectively improve the machining performance of workpieces, which is widely used in the field of titanium alloy machining. A two-dimensional cutting finite element modeling methodology for orthogonal cutting titanium alloy Ti6Al4V was established to analyze the comparisons between conventional machining (CM) and ultrasonic vibration assisted machining and the effects of frequency and amplitude. The simulation results showed that (1) UVAM more easily formed serrated chip than that of CM. The chip segmentation coefficient G S which could quantitatively characterize the segmentation degree of chip showed an increasing trend with the increase of amplitude. (2) The cutting force curve of UVAM had periodic pulse fluctuation due to the effects of vibration in x-direction and y-direction. The main cutting force and the thrust force of UVAM showed the further decrease trend with the increase of frequency and x-direction amplitude. However, the y-direction amplitude made the contrary trend for the cutting force. (3) Meanwhile, with the increase of y-direction amplitude, the plastic and friction dissipation energies increased obviously. The introduction of ultrasonic vibration results in complex changes in the tool-chip contact, mechanical and temperature characteristics of the workpiece. Choosing the suitable vibration parameters will contribute to improving the machinability of titanium alloys.

30 W급 COB LED의 열전소자 이용 강제방열

한재호,임광희,조영태 한국생산제조학회 2019 한국생산제조학회지 Vol.28 No.4

This study focuses on the development and production of 120 W LED street-lamps using four 30 W chip on board (COB) LED modules. The lamps’ heat dissipation efficiency was improved by packaging 30 W COB LEDs and thermoelectric modules. This study was also conducted to reduce the thermoelectric element driving power consumption and minimize the thermoelectric element driving power, resulting from forced heat dissipation. Results indicated that the minimum metal temperature of the metal core printed circuit board (MCPCB) reached 68.1℃ when the thermoelectric power consumption was 0.7 W; a temperature drop effect of approximately 16.1% occurred. The life extension effect is expected to be approximately 48.5% according to the lifespan arithmetic. Thus, this technology can be applied to reduce the temperature and extend the life of COB LED modules; small-sized and lightweight luminaries can be realized by addressing the thermal problem of LED modules.

The effects of special metallic dampers on the seismic behavior of a vulnerable RC frame

Hasan Özkaynak 국제구조공학회 2017 Structural Engineering and Mechanics, An Int'l Jou Vol.61 No.4

Earthquake excitations may induce important amount of seismic energy into structures. Current design philosophy mainly deals with the plastic deformations of replaceable energy dissipating devices rather than damages accumulated on structural members. Since earthquake damage is substantially concentrated on these devices they could be replaced after severe earthquakes. In this study, the efficiency of steel cushion (SC) on seismic improvement of a vulnerable reinforced concrete (RC) frame is determined by means of several numerical simulations. The cyclic shear behaviors of SCs were determined by performing quasi-static tests. The test results were the main basis of the theoretical model of SCs which were used in the numerical analysis. These analyses were performed on three types of RC frames namely bare frame (BF), full-braced frame (FBF) and semi-braced frame (S-BF). According to analysis results; implementation of SCs has considerable effects in reducing the storey shear forces and storey drifts. Moreover plastic energy demands of structural elements were reduced which indicates a significant improvement in seismic behavior of the RC frame preventing damage accumulation on structural elements. Fullbraced frame having SCs with the thickness of 25 mm has better performance than semi-braced frame interms of energy dissipation. However, global energy dissipation demand of S-BF and F-BF having SCs with the thickness of 18 mm are almost similar.

120 W급 LED 가로등 개발을 위한 열전반도체 이용 강제방열

조영태(Young-Tae Cho) 한국생산제조학회 2020 한국생산제조학회지 Vol.29 No.4

This study was carried out to develop 120 W class light-emitting diode (LED) security lights with smaller heat dissipation devices by improving the heat dissipation efficiency compared to existing security lights. Four 30 W class chip-on-board (COB) LED modules were placed in a luminaire, with three modules subjected to forced heat dissipation using thermoelectric elements. The thermoelectric element and LED module were packaged as a unit to improve the performance of the thermoelectric element, and the unit satisfied the optimal conditions for low power energy consumption of the thermoelectric element. When the electric power was 6.4 W, a 24.9% temperature decrease was achieved at the lowest temperature of the metal-core printed circuit board (76.2℃) through forced heat dissipation. Based on the results, the arithmetic lifespan of the LED light could be extended by 100.5%.

The Vibration Performance Experiment of Tuned Liquid Damper and Tuned Liquid Column Damper

Kim Young-Moon,You Ki-Pyo,Cho Ji-Eun,Hong Dong-Pyo The Korean Society of Mechanical Engineers 2006 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.20 No.6

Tuned Liquid damper and Tuned Liquid Column are kind of passive mechanical damper which relies on the sloshing of liquid in a rigid tank for suppressing structural vibrations. TLD and TLCD are attributable to several potential advantages - low costs ; easy to install in existing structures : effective even for small-amplitude vibrations. In this paper, the shaking table experiments were conducted to investigate the characteristics of water sloshing motion in TLD (rectangular, circular) and TLCD. The parameter obtained from the experiments were wave height, base shear force and energy dissipation. The shaking table experiments show that the liquid sloshing relies on amplitude of shaking table and frequency of tank. The TLCD was more effective control vibration than TLD.