• Earthquakes and Structures
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• 제18권1호
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• pp.129-145
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• 2020

Seismic resilience is a key feature for buildings that play a strategic role within the community. In this framework, not only the structural and non-structural elements damage but also the protracted structural dysfunction can contribute significantly to overall seismic damage and post-seismic crisis situations. Reduction of the residual and peak displacements and energy dissipation by replaceable elements are some effective aspects to pursue in order to enhance the resilience. Control systems able to adapt their response based on the nature of events, such as active or semi-active, can achieve the best results, but also require higher costs and their complexity jeopardizes their reliability; on the other hand, a passive control system is not able to adapt but its functioning is more reliable and characterized by lower costs. In this study it is proposed a strategy for the optimization of the dissipative capacity of a seismic resistant system obtained placing in parallel two different groups dissipative Re-Centering Devices, specifically designed to enhance the energy dissipation, one for the low and the other for the high intensity earthquakes. In this way the efficiency of the system in dissipating the seismic energy is kept less sensitive to the seismic intensity compared to the case of only one group of dissipative devices.

• Smart Structures and Systems
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• 제26권2호
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• pp.213-226
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• 2020

In this manuscript, static and dynamic behaviors of geometrically imperfect carbon nanotubes (CNTs) subject to different types of end conditions are investigated. The Doublet Mechanics (DM) theory, which is length scale dependent theory, is used in the analysis. The Euler-Bernoulli kinematic and nonlinear mid-plane stretching effect are considered through analysis. The governing equation of imperfect CNTs is a sixth order nonlinear integro-partial-differential equation. The buckling problem is discretized via the differential-integral-quadrature method (DIQM) and then it is solved using Newton's method. The equation of linear vibration problem is discretized using DIQM and then solved as a linear eigenvalue problem to get natural frequencies and corresponding mode shapes. The DIQM results are compared with analytical ones available in the literature and excellent agreement is obtained. The numerical results are depicted to illustrate the influence of length scale parameter, imperfection amplitude and shear foundation constant on critical buckling load, post-buckling configuration and linear vibration behavior. The current model is effective in designing of NEMS, nano-sensor and nano-actuator manufactured by CNTs.

• The Journal of Asian Finance, Economics and Business
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• 제7권9호
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• pp.791-800
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• 2020

This study aims to determine the technical aspects of organic food systems in rice agribusiness and analyze the pattern of economic and institutional structures of agribusiness in East Java of Indonesia. Also, this study investigates the feasibility of farming and understands the strategies of rice agribusiness development. This study was conducted in several places in East Java of Indonesia, covering the district of Blitar, Kediri, Bondowoso, Tulungagung, and Malang. The data were collected through a structured questionnaire and focus group discussion. Furthermore, the data were analyzed using efficiency analysis, revenues analysis, and SWOT analysis. The findings indicated that, technically, the district of Bondowoso, Malang, Kediri, and Tulungagung had implemented the organic systems, while the district of Blitar applied under semi-organic systems. The pattern of economic institutions of agribusiness commodity consists of the production facility, farming, post-harvest and product processing, marketing, and support services institutional. These results showed that the organic rice farming is economically viable, and the government support was provided in the form of the establishment of development centers, the facilitation of agricultural machines, integrated crop management field school, and the organic certification. These findings suggest that several places in East Java have prospective opportunities for production of rice agribusiness development.

• 대한기계학회논문집A
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• 제25권5호
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• pp.823-833
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• 2001

In recent years, the subject of remaining life assessment has drawn considerable attention in chemical plants, where various structural components typically operate at high temperature an pressure. Thus a life prediction methodology accounting for high temperature creep fracture is increasingly needed for the components. Critical defects in such structures are generally found in the form of semi-elliptical surface crack, and the analysis of which is consequently an important problem in engineering fracture mechanics. On this background, we first develop an auto mesh generation program for detailed 3-D finite element analyses of axial and circumferential semi-elliptical surface cracks in a piping system. A high temperature creep fracture parameter C-integral is obtained from the finite element analyses of generated 3-D models. Post crack growth module is further appended here to calculate the amount of crack growth. Finally the remaining lives of surface cracked pipes for various analytical parameters are assessed using the developed life assessment program.

• 한국분말재료학회지
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• 제24권6호
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• pp.494-507
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• 2017

A three-dimensional physical part can be fabricated from a three-dimensional digital model in a layer-wise manner via additive manufacturing (AM) technology, which is different from the conventional subtractive manufacturing technology. Numerous studies have been conducted to take advantage of the AM opportunities to penetrate bespoke custom product markets, functional engineering part markets, volatile low-volume markets, and spare part markets. Nevertheless, materials issues, machines issues, product issues, and qualification/certification issues still prevent the AM technology from being extensively adopted in industries. The present study briefly reviews the standard classification, technological structures, industrial applications, technological advances, and qualification/certification activities of the AM technology. The economics, productivity, quality, and reliability of the AM technology should be further improved to pass through the technology adoption lifecycle of innovation technology. The AM technology is continuously evolving through the introduction of PM materials, hybridization of AM and conventional manufacturing technologies, adoption of process diagnostics and control systems, and enhanced standardization of the whole lifecycle qualification and certification methodology.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제11권2호
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• pp.865-882
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• 2017

To improve passenger convenience and safety, today's vehicle is evolving into a "connected vehicle," which mounts various sensors, electronic control devices, and wired/wireless communication devices. However, as the number of connections to external networks via the various electronic devices of connected vehicles increases and the internal structures of vehicles become more complex, there is an increasing chance of encountering issues such as malfunctions due to various functional defects and hacking. Recalls and indemnifications due to such hacking or defects, which may occur as vehicles evolve into connected vehicles, are becoming a new risk for automakers, causing devastating financial losses. Therefore, automakers need to make voluntary efforts to comply with security ethics and strengthen their responsibilities. In this study, we investigated potential security issues that may occur under a connected vehicle environment (vehicle-to-vehicle, vehicle-to-infrastructure, and internal communication). Furthermore, we analyzed several case studies related to automaker's legal risks and responsibilities and identified the security requirements and necessary roles to be played by each player in the automobile development process (design, manufacturing, sales, and post-sales management) to enhance their responsibility, along with measures to manage their legal risks.

• 음성과학
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• 제13권4호
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• pp.107-126
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• 2006

The aim of this study is to analyze the tonal structures of Korean conjunctive phrases produced by Daegu dialect speakers and show that there are distinctive intonational patterns between dialogic and reading styles. In the experiment, we examined the pitch contour at the edge of conjunctive phrases including '-ko', $'-(i)my{\partial}n'$, $'-(a){\partial}s{\partial}'$, '-(nin)de', '-do' in the base which is made a coordinate and subordinate conjunctive sentence according to the relation of pre-phrase and post-phrase. The results of this study show that '-ko' has L%, $'-(i)my{\partial}n'$ has LH%, $'-(a){\partial}s{\partial}'$ has HL% and '-(nin)de' has LH%, '-do' has LH% in Daegu Dialect. And the results show the conjunctive sentences were about 20% longer when they produced in a dialogic style than in a reading style. The dialogic style has various durations, the duration of the reading style is slower than the dialogic style by a rate of 20%. This suggests that the dialogic style is more dynamic than the reading style, which may be due to the communicative interaction between speakers and listeners.

• E2M - 전기 전자와 첨단 소재
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• 제10권10호
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• pp.1029-1033
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• 1997

A prototype MFSFET using ferroelectric fluoride BaMgF$_4$as a gate insulator has been successfully fabricated with the help of 2 sheets of metal mask. The fluoride film was deposited in an ultrai-high vacuum system at a substrate temperature of below 30$0^{\circ}C$ and an in-situ post-deposition annealing was conducted for 20 seconds at $650^{\circ}C$ in the same chamber. The interface state density of the BaMgF$_4$/Si(100) interface calculated by a MFS capacitor fabricated on the same wafer was about 8$\times$10$^{10}$ /cm$^2$.eV. The I$_{D}$-V$_{G}$ characteristics of the MFSFET show a hysteresis loop due to the ferroelectric nature of the BaMgF$_4$film. It is also demonstrated that the I$_{D}$ can be controlled by the “write” plus which was applied before the measurements even at the same “read”gate voltage.ltage.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 하계학술대회 논문집 B
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• pp.477-479
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• 1998

This paper presents the results of the field of an improved GPS navigation algorithm. The improved GPS navigation algorithm is a modified Kalman filter which is designed to be ideally suited to car navigation in urban area where lack of GPS visibility is the major problem because of the frequent blockage of the GPS signals by tall buildings and other structures. The method allows the user to estimate its position when the number of visible GPS satellites becomes less than four by using altitude fixing and clock bias estimation techniques. The two estimation techniques are integrated with the Kalman filter in a mutually compensating manner and it is shown that the 3-dimensional position accuracy is well maintained when the number of the visible satellites drops down to two for a reasonable period of time. The post processing results are included to show the improved performance of the modified algorithm over a normal conventional GPS Kalman filter.

• 대한조선학회논문집
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• 제28권1호
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• pp.182-188
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• 1991

구조물의 비선형 거동을 추적 조사하는 비선형 유한요소 해석에서 하중증분을 사용하는 Newton-Raphson방법은 임계점 근처에서는 수렴이 안되는 단점을 갖고 있으므로 구조물의 거동이 심한 비선형 경로(nonlinear path)를 포함하고 있는 구조물의 거동을 조사하기 위해서는 Newton-Raphson 방법의 부가적인 수정이 필요하다. Newton-Raphson 방법의 수정보완 방법으로 Riks에 의해 제안된 구속조건식을 사용하여 반복계산하는 arc-length method로써 접선강성벡터에서 수직인 방향으로 접근하는 방법(normal arc-length method)과 접선강성벡터가 원호를 그리며 비선형 경로에 접근해 가는 방법(cylindrical arc-length method)을 사용하였으며 또한 각 단계에서 비선형의 정도에 따라 arc-length를 조절하는 자동하중 증분법을 사용하였다. 비선형 수치해석의 예로 경사진 외팔보, 단순 아치구조, 쉘 구조 및 편심 보강평판의 비선형 거동을 추적 조사하였다.