Rigidity of Distance-based Formations with Additional Subtended-angle Constraints

Myoung-Chul Park,Hong-Kyong Kim,Hyo-Sung Ahn 제어로봇시스템학회 2017 제어로봇시스템학회 국제학술대회 논문집 Vol.2017 No.10

In this paper, we propose a new concept of rigidity, named weak rigidity, using distance and subtended-angle constraints. The classical rigidity of formation is used in the field of distance-based formation control as a fundamental tool to guarantee a locally unique formation shape with given inter-agent distances. We assume that there are some angle constraints in addition to the existing distance constraints. Then the formation could result in a rigid formation shape even if it is not rigid in the viewpoint of classical rigidity. Weak rigidity distinguishes whether the formation with additional angle constraints can maintain its shape. Relation between classical rigidity and weak rigidity is addressed and used to derive some useful results.

Mechanism of Packing Rigidity Gain in Sand Aging: From the Perspective of Structural Order Evolution

Chengjun Liu,Pei Tai,Zhaofeng Li,Wenbiao Hu 대한토목학회 2022 KSCE JOURNAL OF CIVIL ENGINEERING Vol.26 No.6

Rigidity gain can be observed in sand aging but is usually accompanied by minute densification.This phenomenon is inconsistent with the conventional diagram of rigidity/jamming transition for granules and therefore too enigmatic to be utilized in the field by engineers. Therefore, this study aims to reveal the mechanism of rigidity gain and reconcile the inconsistency in sand aging. The aging processes of two sand packings with the same mono-sized spheres but different initial densities were reproduced via discrete element method simulations. In the simulations, sudden increases in the solid fraction destroyed the similarity between the evolution processes of rigidity gain and densification, confirming the inadequacy of explaining this gain considering densification alone. The bond-orientational order remained almost unchanged, while the contact-force order generally increased over time with distinct drops, similar to the change in rigidity gain. This evolution pattern is attributed to the laws of thermodynamics, which require the Gibbs energy of the sand packing to decrease over time, and contact-force order reduction assists with this decrease. Simultaneously, this reduces the nonaffinity under shear and rigidity demolition, consequently dominating the rigidity gain mechanism in sand aging. Based on these findings, the conventional diagram of rigidity transition was modified to jointly consider the effects of the solid fraction and structural orders. The proposed diagram can depict how the sand packing rigidity is enhanced over time and can better guide the consideration of the sand aging effect in the field.

지붕마감재 강성효과를 고려한 2방향 그리드 단층돔의 좌굴특성에 관한 연구

박상훈,석창목,정환목,권영환 한국공간구조학회 2002 한국공간구조학회지 Vol.2 No.1

Two way grid single-layer domes are of great advantage in fabrication and construction because of the simple fact that they have only four members at each junction. But, from a point of view of mechanics, the rectangular latticed pattern gives rise to a nonuniform rigidity-distribution in the circumferential direction. If the equivalent rigidity is considered in the axial direction of members, the in-plane equivalent shearing rigidity depends only on the in-plane bending rigidity of members and its value is very small in comparison to that of the in-plane equivalent stretching rigidity. It has a tendency to decrease buckling -strength of dome considerably by external force. But it is possible to increase buckling strength by the use of roofing covering materials connected to framework. In a case like this, shearing rigidity of roofing material increases buckling strength of the overall structure and can be designed economically from the viewpoint of practice. Therefore, the purpose of this paper, in Lamella dome and rectangular latticed dome that are a set of 2-way grid dome, is to clarify the effects of roofing covering materials for increasing of buckling strength of overall dome. Analysis method is based on FEM dealing with the geometrically nonlinear deflection problems. The conclusion were given as follows: 1. In case of Lamella domes which have nearly equal rigidity in the direction of circumference, the rigidity of roofing covering materials does not have a great influence on buckling-strength, but in rectangular latticed domes that has a clear periodicity of rigidity, the value of its buckling strength has a tendency to increase considerably with increasing rigidity of roofing covering materials 2. In case of rectangular latticed domes, as rise-span-ratio increases, models which is subjected to pressure -type-uniform loading than vertical-type-uniform loading are higher in the aspects of the increasing rate of buckling- strength according to the rate of shear reinforcement rigidity, but in case of Lamella dome, the condition of loading and rise-span-ratio do not have a great influence on the increasing rate of buckling strength according to the rate of shear reinforcement rigidity.

강직(强直) 및 경직(硬直)의 소양경(少陽經) 사침치료(瀉針治療)에 대한 임상적(臨床的) 고찰(考察)

박진용,김진규,김수정,이운석,김용찬,정명걸,Park, Jin-Yong,Kim, Jin-Gyu,Kim, Soo-Jung,Lee, Woon-Suk,Kim, Yong-Chan,Jung, Myong-Gul 대한한방내과학회 2000 大韓韓方內科學會誌 Vol.21 No.5

Objective : This study was to investigate Soyang-Kyong negative acupuncture treatment of spasticity or rigidity in 41 patients. Methods : Let Sadok, Yangnungch' on, Kuho in side of spasticity or rigidity have negative acupuncture in the skin. Result and Conclusion : 1. Spasticity or rigidity was improved 33 case of 41 case by Soyang-Kyung negative acupuncture. 2. The spasticity was improved more than the rigidity. 3. Spasticity or rigidity of Basal Ganglia, Periventricular Whete Matter, Thalamrs is improved more than Spasticity or rigidity of M.C.A territory, Pons. 4. Spasticity or rigidity of Cb-mfaction is improved more than Spasticity or rigidity of Cb-hemorrloge.

Modelling and classification of tubular joint rigidity and its effect on the global response of CHS lattice girders

Wang, Wei,Chen, Yiyi Techno-Press 2005 Structural Engineering and Mechanics, An Int'l Jou Vol.21 No.6

In engineering practice, tubular connections are usually assumed pinned or rigid. Recent research showed that tubular joints may exhibit non-rigid behavior under axial or bending loads. This paper is concerned with establishing a new classification for tubular joints and investigating the effect of joint rigidity on the global behavior of CHS (Circular Hollow Section) lattice girders. Parametric formulae for predicting tubular joint rigidities are proposed, which are based on the finite element analyses through systematic variation of the main geometric parameters. Comparison with test results proves the reliability of these formulae. By considering the deformation patterns of respective parts of Vierendeel lattice girders, the boundary between rigid and semirigid tubular connections is built in terms of joint bending rigidity. In order to include characteristics of joint rigidity in the global structural analysis, a type of semirigid element which can effectively reflect the interaction of two braces in K joints is introduced and validated. The numerical example of a Warren lattice girder with different joint models shows the great effect of tubular joint rigidities on the internal forces, deformation and secondary stresses.

명목임금의 경직성과 고용변동성

황상현,이진영 강원대학교 경영경제연구소 2019 Asia-Pacific Journal of Business Vol.10 No.4

Using Korean Labor and Income Panel Study data, this paper estimates nominal wage rigidity in Korea by industry from 2005 to 2017 and evaluates the level of inefficiency of Korean labor market. And, after estimating employment volatility by industry using the Labor Force Survey at Establishments data for Korea, we combine the nominal wage rigidity and the employment volatility estimates and analyze the effect of nominal wage rigidity on employment volatility in Korea from 2011 to 2017. If the level of wage rigidity is high, it may be hard for the labor market to be in the equilibrium, and therefore, the market may have inefficiency. We find that the inefficiency of the labor market in Korea have increased from 2005 to 2017 and the industry of accommodation and food service activities has the highest level of inefficiency over the period. We also find that one-percent-point increase in wage rigidity increases employment volatility by 2.3-2.9 percent and the positive effect is bigger for workers with part-time and temporary jobs. The result implies that firms may adjust their labor costs by changing the number of casual workers, rather than permanent workers, when the labor market suffers from a high level of wage rigidity.

心の硬さに基づく就職活動支援に関する研究

山下利之,長縄久生,劉亨淑 한국일본근대학회 2011 일본근대학연구 Vol.0 No.32

The personality construct “rigidity” refers to lacking in flexibility and adaptability when thinking and solving the problems. “More rigid” persons are more difficult to adapt themselves to new surroundings, to behave in accordance with the circumstances, and to change the strategies according to the problems than “less rigid” persons. “Rigidity” sometimes hinders person’s vocational activities and occupational decision making. Therefore, when college students make career choices, it is very useful for them to comprehend the nature of their own “rigidity.” In the present study, we examined and compared Japanese and Korean college students’ vocational motives and views, and their “rigidity.” We moreover constructed the rigidity scale, and developed the framework of supporting system by using “rigidity” for college students’ career decision making.

아동기 외상 유형이 대학생의 대인관계 철회에 미치는 영향 : 심리적 경직성의 매개효과

박선미(Sun Mee Park),이주영(Joo Young Lee) 한국심리치료학회 2021 한국심리치료학회지 Vol.13 No.1

본 연구에서는 아동기 외상 경험 중에서 신체적 학대와 정서적 학대 및 방임이 심리적 경직성을 매개로 하여 대학생의 대인관계 철회에 어려움을 야기할 것으로 가정하였다. 본 연구에서는 연구대상자 선정 방법에 있어서 자기보고식 아동학대 측정도구를 사용하여 외상을 측정하는 것이 한계가 있다고 판단하여 실제 외상 여부를 검증하기 위해 임상가에 의한 1:1 면접을 함께 실시하여 외상 경험이 있는 연구대상 152명을 선별하였다. 분석 결과, 신체적 학대 경험이 많을수록 대인관계 철회가 감소하는 경향이 있었고, 심리적 경직성의 매개효과는 나타나지 않았다. 정서적 학대는 심리적 경직성을 매개로 대인관계 철회에 영향을 미치는 것으로 나타난 반면 방임은 심리적 경직성의 매개효과는 나타나지 않았으며, 대인관계 철회에 직접적으로 영향을 미치는 것으로 나타났다. 즉, 정서적 학대 경험이 많을수록 심리적 경직성이 높아지며 그로 인해 대인관계 철회가 발생하는 것으로 볼 수 있다. 본 연구는 아동기 외상 경험이 성인기 초기인 대학생의 대인관계에까지 지속적으로 영향을 미친다는 사실을 보여주었으며, 아동기 외상의 하위 유형에 따라 심리적 경직성의 매개효과가 달라질 수 있음을 경험적으로 입증하였다. 즉, 정서적 학대의 경우에만 심리적 경직성이라는 기제를 통해 대인관계 철회가 초래된다는 것을 보여줌으로써 이들에 대한 심리치료적 개입의 목표 설정에 유용하게 활용될 수 있는 근거를 제공하였다. 아동기 외상 경험은 성인기 초기까지 그 영향력이 지속되므로 외상 경험자에 대한 조기 발견은 물론 이들을 위한 체계적인 지원 방안이 성인기까지도 마련되어야 함을 보여주었다. The current study hypothesizes that childhood trauma experiences including physical abuse, emotional abuse, and neglect, would cause interpersonal withdrawal in college students, with psychological rigidity working as a mediating factor. Since selfreported child abuse measurement tools are limited in qualitatively studying trauma, the current study employed one-on-one clinical interviews on 152 subjects with trauma experiences. The analysis revealed that interpersonal withdrawal tends to decline when there are more physical abuse experiences, although the study found no mediating effect of psychological rigidity. Emotional abuse significantly influenced interpersonal withdrawal mediated by psychological rigidity. However, neglect directly affected interpersonal withdrawal with no mediating effect. That is, more experiences of emotional abuse increase psychological rigidity, which in turn creates interpersonal withdrawal. The current study indicates that trauma experiences during childhood continue to impact interpersonal relationships in college students in their early adulthood. It also provides an empirical support that different mediating effects of psychological rigidity are found depending on the subtype of childhood trauma. That is, by showing that emotional abuse is the only type of abuse leading to interpersonal withdrawal through psychological rigidity, the current study offers information that may be useful in establishing goals for psychotherapeutic interventions for such patients. The current study demonstrates that early discovery of childhood trauma is necessary because negative outcomes of such experiences can continue into early adulthood, in addition to the need for continued systematic support for patients in their early adulthood.

Monetary Business Cycles and Price Setting under Monopolistic Competition

Yun, Tack THE KOREAN ECONOMIC SOCIETY 1998 JOURNAL OF ECONOMIC THEORY AND ECONOMETRICS Vol.4 No.1

This paper analyzes quantitative effects of money supply and technology shocks in a series of economies with nominal price rigidity. I construct complete dynamic monopolistically competitive models of money with several alter-native specifications of the ways in which prices are set, including alternative assumptions as to the number of periods in advance for which prices are set. The quantitative predictions of alternative specifications, including the case of complete price flexibility, are then contrasted. The alternative multi-period staggered price decisions that are used in this paper are comparable to the ones analyzed in Calvo(1983), Fischer (1977), and Taylor (1979) respectively. It is demonstrated that nominal price rigidity leads an expansionary money supply shock to display positive persistent and significant effects on real equilibrium quantities, including real output, consumption, investment, employment, and real wage. It is also shown that real effects of monetary shocks in Fisher type model last for only those periods which prices are set in advance, while Taylor type model display periodic damped fluctuations. In addition, nominal price rigidity models with Calvo type staggering allow one to be able to consider arbitrarily slow adjustment of prices without having to work with a large state space. Finally, it is shown that a small amount of nominal price rigidity is needed to match the volatility of output observed in post-war U.S. data, while a sufficiently large amount of nominal price rigidity is needed to match the volatility of inflation observed in post-war U.S. data.

Effective flexural rigidities for RC beams and columns with steel fiber

Habib Akbarzadeh Bengar,Mohammad Asadi Kiadehi,Javad Shayanfar,Maryam Nazari 국제구조공학회 2020 Steel and Composite Structures, An International J Vol.34 No.3

Influences of different variables that affect the effective flexural rigidity of reinforced concrete (RC) members are not considered in the most seismic codes. Furthermore, in the last decades, the application of steel fibers in concrete matrix designs has been increased, requiring development of an accurate analytical procedure to calculate the effective flexural rigidity of steel fiber reinforced concrete (SFRC) members. In this paper, first, a nonlinear analytical procedure is proposed to calculate the SFRC members’ effective flexural rigidity. The proposed model’s accuracy is confirmed by comparing the results obtained from nonlinear analysis with those recorded from the experimental testing. Then a parametric study is conducted to investigate the effects of different parameters such as varying axial load and steel fiber are then investigated through moment-curvature analysis of various SFRC (normal-strength concrete) sections. The obtained results show that increasing the steel fiber volume percentage increases the effective flexural rigidity. Also it’s been indicated that the varying axial load affects the effective flexural rigidity. Lastly, proper equations are developed to estimate the effective flexural rigidity of SFRC members.