• Journal of Mechanical Science and Technology
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• 제14권10호
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• pp.1061-1071
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• 2000

Linear cyclic systems (LCS's) are a class of systems whose dynamic behavior changes periodically. Such a cyclic behavior is ubiquitous in systems with fundamentally repetitive motion. Yet, the knowledge of the noise and vibration transmission paths in LCS's is quite limited due to the time-varying nature of their dynamics. The first part of this two-part paper derives a generic expression that describes how the noise and/or vibration are transmitted between two (or multiple) points in the LCS's. In Part II, experimental validation of the theoretical development of Part I is provided. The noise and vibration transmission paths of the scroll and rotary compressors (two typical LCS's) are examined to show that the LCS's indeed generate a series of amplitude modulated input signals at the output, where the carrier frequencies are harmonic multiples of the LCS' fundamental frequency. The criterion proposed in Part I to determine how well a given LCS can be approximated as a linear time-invariant systems (LTIS) is applied to the noise and vibration transmission paths of the two compressors. Furthermore, the implications of the experimental validations/applications are discussed in order to assess the applicability of the noise/vibration source and transmission path identification techniques based on the assumption that the system under consideration is linear and time-invariant.

• Computers and Concrete
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• 제25권4호
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• pp.327-341
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• 2020

Advanced forms of structural design (e.g., displacement-based methods) require knowledge of the non-linear force-displacement behavior of both the overall building and individual lateral load resisting elements, i.e., walls or building cores. Similarly, understanding the non-linear behaviour of the elements in a structure can also allow for a less conservative structural response to be calculated by better understanding the cracked (i.e., effective) properties of the various RC elements. Calculating the non-linear response of an RC section typically involves using 'black box' analysis packages, wherein the user may not be in complete control nor be aware of all the intricate settings and/or decisions behind the scenes. This paper introduces a user-friendly and transparent analysis program for predicting the back-bone force displacement behavior of slender (i.e., flexure controlled) RC walls, building cores or columns. The program has been validated and benchmarked theoretically against both commonly available and widely used analysis packages and experimentally against a database of 16 large-scale RC wall test specimens. The program, which is called WHAM, is written using Microsoft Excel spreadsheets to promote transparency and allow users to further develop or modify to suit individual requirements. The program is available free-of-charge and is intended to be used as an educational tool for structural designers, researchers or students.

• The Journal of Asian Finance, Economics and Business
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• 제8권1호
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• pp.71-79
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• 2021

This study investigates the capital structure policy among Indonesian public companies. Previous studies suggest that capital structure policy could follow either static or dynamic behavior. The sample data used in this study was companies in the manufacturing sector, divided into three sub-sectors: the basic and chemical industry, miscellaneous industry, and the consumer goods industry. This study uses panel data from 2010 to 2018, with the Generalized Least Square (GLS) method and compared whether the fixed effect model is better than the common effect model. The results show that the dynamic and non-linear model tests can explain the capital structure determinants than the static and linear models. The dynamic model shows that the capital structure of a certain year is influenced by the capital structure of the previous year. The findings indicate that the company performs some adjustments in its capital structure policy by referring to the previous debt ratio, which implies support to the trade-off theory (TOT). The study also shows that profitability, tangible assets, size, and age explain the variation of capital structure policy. The patterns on the dynamic and non-linear confirm that capital structure runs in a nonlinear pattern, based on the sector, company condition, and the dynamic environment.

• 한국전산구조공학회논문집
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• 제13권3호
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• pp.361-371
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• 2000

RC 구조물은 서로 다른 재료적 특성을 지닌 콘크리트와 철근의 복합구조이고, 특히 콘크리트는 복잡한 소성거동을 나타내는 재료이다. 따라서 RC 구조물의 소성해석을 위해서는 콘크리트와 철근 각각의 재료특성과 소성거동을 묘사할 수 있는 세밀한 모델링 기법이 필요하지만, 이때 발생하는 모델링의 어려움, 모델링 규모, 계산용량 및 수렴성 등의 문제점으로 인하여 소성해석 수행에 많은 시간과 노력이 소요되거나 해석자체가 불가능하게 된다. 따라서 본 논문에서는 간편한 RC 구조물의 소성해석을 위해 RC 부재와 동일한 소성거동을 나타내는 균질·등방 재료로의 물성치환 방법을 제시하였다. 물성치환 원리는 RC 부재의 소성거동 특성, 즉 항복모멘트, 항복곡률 및 극한모멘트, 극한곡률로 표현되는 bi-linear 형태의 모멘트-곡률 관계를 이용하여, 이와 동일한 모멘트-곡률 관계(bi-linear 형태의 응력 변형률 관계)를 갖는 균질·등방 재료를 생성하였다. 또한 실제 RC 부재 해석모델과 치환된 균질·등방 재료를 이용한 해석모델에 대한 소성해석 결과를 비교·분석하여 본 연구의 타당성을 검증하였다.

• 대한토목학회논문집
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• 제28권1C호
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• pp.31-40
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• 2008

본 연구에서는 지진하중을 받는 Single Column/Shaft의 내진해석으로 의사정적해석법을 적용하였으며 해석상에서 지반의 비선형 거동특성을 나타내는 다양한 수평방향 하중전이특성(p-y 곡선, Bi-linear 곡선)를 이용하여 지반-말뚝의 상호작용을 고려하였다. 비선형 지반모델을 적용한 해석은 지반-말뚝 시스템의 지진거동을 간편히 예측할 수 있었으며 동일한 해석조건에서 응답변위법에 의한 Single Column/Shaft의 수평거동이 진도법에 근거하여 산정한 해석결과보다 크게 예측되었다. 두부경계조건과 상대강성이 Single Column/Shaft의 단면력에 미치는 영향을 분석하기 위해 다양한 지반모델에 대한 변수연구를 수행한 결과, 두부경계가 고정이고 말뚝강성이 감소할수록 수평변위가 작은 것으로 나타났으며, JRA의 Bi-linear 지반모델을 적용한 해석은 Single Column/Shaft의 수평거동을 비교적 정확히 예측하였다.

• Computers and Concrete
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• 제16권1호
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• pp.17-35
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• 2015

In this study, linear and non-linear response of a masonry wall that includes an opening was presented. The masonry wall was modeled with two-dimensional finite elements. Smeared crack model that includes the strain softening behavior was selected to the masonry wall material. For the numerical application, linear and non-linear analyses of the masonry wall were carried out using east-west and vertical components of the 1992 Erzincan and 2003 $Bing{\ddot{o}}l$ earthquake acceleration records. Linear and non-linear solutions were compared each other. The displacement and stress results at the selected points of the masonry wall and crack propagation in the masonry wall were presented for both earthquake acceleration records.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2004년도 춘계학술대회 논문집
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• pp.347-353
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• 2004

Due to various advantages over the conventional linear motion device such as ball-screw, linear motors have been used in wide variety of industrial applications for years. Driven by increased demand for precision machine tools, the importance of high positioning accuracy, high stiffness and high thrust are greatly increasing. The merits of linear motor are high speed high acceleration and good positioning accuracy. In addiction, Linear motor for high qualify machine tool call for high thrust, high stiffness. In this paper, thrust ripple, detent force and thermal behavior are considered for the development of high performance linear motor whose thrust is up to 1,900N. This paper presents a comprehensive study for an iron core type linear motor characteristics that include the influence of PM position on thrust ripple by detent force and motor dynamics as well.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2004년도 추계학술대회 논문집
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• pp.363-368
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• 2004

Due to various advantages over the conventional linear motion device such as ball-screw, linear motors have been used in wide variety of industrial applications for years. Driven by increased demand for precision machine tools, the importance of high positioning accuracy, high stiffness and high thrust are greatly increasing. The merits of linear motor are high speed, high acceleration and good positioning accurcy. In addition, Linear motor for high quality machine tool call for high thrust, high stiffness. In this paper, thrust ripple, detent force and thermal behavior are considered for the development of high performance linear motor whose thrust is up to 10,000N. This paper presents a comprehensive study for an iron core type linear motor characteristics that include the influence of PM position on thrust, thrust ripple by detent force and motor dynamics as well.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2002년도 추계학술대회 논문집
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• pp.423-428
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• 2002

Due to various advantages over the conventional linear motion device such as ball-screw, linear motors have been used in wide variety of industrial applications for years. Driven by increased demand for precision machine tools, the importance of high positioning accuracy, high stiffness and high thrust are greatly increasing. The merits of linear motor are high speed, high acceleration and good positioning accurcy. In addition, Linear motor for high quality machine tool call for high thrust, high stiffness. In this paper, thrust ripple, detent force and thermal behavior are considered for the development of high performance linear motor whose thrust is up to 4,000N. This paper presents a comprehensive study for an iron core type linear motor characteristics that include the influence of PM position on thrust, thrust ripple by detent force and motor dynamics as well.

• Korea-Australia Rheology Journal
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• 제12권3_4호
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• pp.181-186
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• 2000

Rheological Properties of polypropylenes having different molecular structures (linear polypropylene (PPL) and branched one (PPB)) were studied. Both the extensional flow and oscillatory shear flow properties were checked. Especially, the melt strength of polypropylenes having various shear history were investigated by using in-house-made Rheometer (called SMER). Compared to linear polypropylene, the branched polypropylene shows enhanced melt strength during extensional flow due to the retarded relaxation of molecules. When the slope of melt tension was plotted against take up speed of melt strand, the characteristic peak was observed in case of branched polypropylene, while the linear polypropylene shows only monotonously decreasing pattern. This entanglement was partially disrupted by physical forces such as shear during melt extrusion. However, the melt strength of PPB after multiple extrusion is still higher than PPL, implying the loss of elasticity during multiple extrusion is not so comprehensive. On dynamic experiments, PPB shows typical shear thinning behavior and the tangent delta of PPB is lower than PPL, reflecting high elasticity of PPB.