• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2003년도 추계학술대회논문집
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• pp.60-65
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• 2003

In this study, for estimating responses of a controlled structure and determining the maximum control force of velocity-dependent damping devices, three estimation models such as Fourier envelope convex model, probability model, and Newmark design spectrum are used. For this purpose, a procedure proposed by Gupta (1990) for estimating spectral velocity using pseudo-spectral velocity which is given by the estimation models is used and modified to consider the effects of increased damping ratio by the damping device. Time history results indicate that Newmark design spectrum gives the best estimation of maximum control force for over all period structures.

• Structural Engineering and Mechanics
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• 제21권3호
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• pp.237-254
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• 2005

This article deals with the reconstruction of an impact force. This requires to take measurements from the impacted structures and then to deconvolve those signals from the impulse response function. More precisely, the purpose of the work described here is to analyse the method of deconvolution and the problems that it implies. Thus, it is highlighted that the associated deconvolution problem depends on the location of the measurement points: it is possible or not to reconstruct the force of impact in function of the location of this point. Then, the role of the antiresonances is linked up with this problem. The singular value decomposition is used to understand these difficulties. Numerical predictions are compared and validated with experiments.

• 건축역사연구
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• 제21권3호
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• pp.7-28
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• 2012

This study is intended to Mindori structure which is general private houses' structural type among traditional types and is a basic study to confirm structural characteristics of Hwatong connection which is general connection type of column-beam-cross beam. It is aimed to analyze how main member, column, such as size, figure, thickness of Sungetuk and Dugeup affect on structure. Following conclusions are drawn. 1. According to connection conditions, models with big coefficient of friction show stable hysteretic behavior until the angle rotation of member reaches 1/60 and models with small coefficient of friction show dramatical increase in load after the angle rotation of member reaches 1/24. After the angle rotation of member reaches 1/30, separation distance of members is identified physically and cracks are not observed. 2. Specimens with big coefficient of friction show similar inner force regardless of column size(except column size 150mm) and models with small coefficient of friction show increasing inner force as the column size increases. Specimens with same sectional area have similar inner force even though the column figures are different. The thickness of Sungetuk and Dugeup doesn't affect inner force greatly, however, when the thickness of Sungetuk is thin, it could lead to failure of structure as it breaks. 3. The bigger the size of column and the coefficient of friction are, the smaller Bending stiffness depreciation ratio is. 4. Energy Dissipation Efficiency differs from the coefficient of friction. When the coefficient of friction is big, square column shows bigger than round one and it is bigger when the thickness of Sungetuk and Dugeup is thicker. When the coefficient of friction is small, round column shows bigger than square one.

• 한국자동차공학회논문집
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• 제15권4호
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• pp.83-93
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• 2007

This paper represents the development of 3-axises loadcell for measuring the side-force of suspension module of MPV(Multi Purposed Vehicle). The side force causes the failure of damper, such as leakage. The loadcell was developed using strain gauges, and the Wheastone bridge circuit to compensate for the cross-talk between the each axises and the measurement error by temperature. Structure analysis of loadcell was accomplished with FEM(Finite Element Method) to optimize the location of strain gages. The design optimization for important factors that have an effect on performance of loadcell was accomplished by using DOE(Design of Experiment). Loadcell was produced and successfully tested, showing good sensitivity and low cross-talk. The cross-talk of the developed loadcell is bellow 5%. The load history was measured at proving ground. The maximum side-force, the longitudinal force, and vertical force of MPV are 4.2 kN, 8.0 kN, and 17.0 kN, respectively, at Belgian road.

• 한국전문물리치료학회지
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• 제11권4호
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• pp.51-60
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• 2004

Falls are common, costly, and a leading cause of death among older adults. The major predisposing factors of a fall may include age-related deterioration in the dynamic system composed of auditory, somatosensory, vestibular, visual, musculoskeletal, and neuromuscular subsystems. Older adults with a history of frequent falls demonstrated significant reductions in gait velocity, muscle force production, and balance performance. These altered neuromechanical characteristics may be further exaggerated when faced with conflicting multisensory conditions. Despite the important contribution of multisensory function on the sensorimotor system during postural and locomotor tasks, it remains unclear whether multisensory intervention will produce dynamic balance improvement during locomotion in older adults with a history of frequent falls. Therefore, the purpose of this paper is to address important factors associated with falls in elderly adults and provide theoretical rationale for a multisensory intervention program model.

• 한국연극학
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• 제48호
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• pp.51-84
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• 2012

In Korea, historical plays took an epoch-making turn from the previous historical plays in terms of approaches to topic and material and methods of rewriting history in the 1990s. Historical plays became dehistoricized with individual, everyday life, and faction emerging as major codes of historical plays according to mistrust in history and grand narrative as the original and disappearance of trust in the growth and totality of history. A new trend became dominant of presenting fictionality prominent instead of reproduction of history and freely playing with history outside the context. While modern historical plays were subject to the content of history, post-modern historical plays sought after new history writing to tell a new story on history within a framework of fiction. Focusing on some of the trends in post-modern historical plays since the 1990s, which include play with history, daily life-style history writing, and reproduction patterns of colonial modernity, this study examined the goals, representations, and text strategies of new history writing in three historical plays, Generation After Generation(2000) by Park Geunhyung, The Mercenaries(2000) by Park Sujin, and Chosun Detective Hong Yunshik(2007) by Sung Giwoong. In Generation After Generation, the author adopts a plot of starting with the present and tracing back to the past, breaking down the myth of racially homogeneous nation. At the same time, he discloses that the colonial history is not just by the oppressive force of Japan but also by the voluntary cooperation of Korean people. That is, we are also accountable for the colonial history of the nation. The Mercenaries contrasts the independence movement during the colonial period against the modern history developed after Liberation, thus highlighting the still continuing coloniality, namely post-colonial present. The past is presented as the "phantom of history" making its appearance according to the request of the present hoping for salvation. The author politicizes history and grants political wishes to history by summoning the history by personal memories such as fictional diaries and letters with Messiah-like images opposed to the present of collapse and catastrophe. In Chosun Detective Hong Yunshik, the author makes an attempt at the microscopic reproduction of daily life by approaching the 1930s as the modern period when capitalist daily life started to take root. The lists of signs comprising daily life in colonial Gyeongseong are divided between civilization and savagery and between modern and premodern. With the progress of narrative, however, they become mixed together and reversed in the representation system in which the latter overwhelms the former.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2001년도 춘계학술대회 논문집
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• pp.144-151
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• 2001

The development history of seismic design and analysis methods considering seismic force in soil-structure dynamic interaction are presented. Determination of seismic intensity in static analysis of both seismic and modifided seismic methods is discussed and preferable method in future seismic design is proposed.

• 대한인간공학회지
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• 제24권2호
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• pp.65-70
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• 2005

Evaluation of repetitiveness for upper extremity intensive tasks is essential to determine the level of risk for upper extremity musculoskeletal disorders at the workplace. However, experimental data available to establish the acceptable levels of repetitiveness for various postures and forces is lacking. The present study examined the maximum acceptable frequencies(MAFs; motions/min.) of shoulder, elbow, wrist, and index finger motions at different forces(1kgf and 4kgf for shoulder, elbow, and wrist; 0.25kgf and 1 kgf for index finger) in sitting. Seventeen right-handed males in 20s without having any history musculoskeletal disorders participated in the MAF experiment. The participants determined their MAFs for the upper extremity motions by using the self-adjustment method and their work pulse(increase in heart rate; beats/min.) and rating of perceived exertion(RPE) were measured when working at MAF. The MAFs of elbow, wrist, and index finger motions for each force level were about 2, 3, and 6 times the corresponding MAF(9 at the high force and 24 at the low force) of shoulder motion and the MAFs at the low force increased about 2 times those at the high force. The work pulses of elbow, wrist, and index finger motions for each force level were 70%, 50%, and 30% of the corresponding work pulse(17 at the high force and 12 at the low force) of shoulder motion and the work pulses at the low force were about 70 % of those at the high force. Lastly, the RPEs of the upper extremity regions were about level 3(moderate) or below.

• Structural Engineering and Mechanics
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• 제59권6호
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• pp.1037-1054
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• 2016

Structural parameter evaluation and external force estimation are two important parts of structural health monitoring. But the structural parameter identification with limited input information is still a challenging problem. A new simultaneous identification method in time domain is proposed in this study to identify the structural parameters and evaluate the external force. Each sampling point in the time history of external force is taken as the unknowns in force evaluation. To reduce the number of unknowns for force evaluation the time domain measurements are divided into several windows. In each time window the structural excitation is decomposed by orthogonal polynomials. The time-variant excitation can be represented approximately by the linear combination of these orthogonal bases. Structural parameters and the coefficients of decomposition are added to the state variable to be identified. The extended Kalman filter (EKF) is augmented and selected as the mathematical tool for the implementation of state variable evaluation. The proposed method is validated numerically with simulation studies of a time-invariant linear structure, a hysteretic nonlinear structure and a time-variant linear shear frame, respectively. Results from the simulation studies indicate that the proposed method is capable of identifying the dynamic load and structural parameters fairly accurately. This method could also identify the time-variant and nonlinear structural parameter even with contaminated incomplete measurement.

• Structural Monitoring and Maintenance
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• 제3권3호
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• pp.195-214
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• 2016

Monitoring of impact loads is a very important technique in the field of structural health monitoring (SHM). However, in most cases it is not possible to measure impact events directly, so they need to be reconstructed. Impact load reconstruction refers to the problem of estimating an input to a dynamic system when the system output and the impulse response function are usually known. Generally this leads to a so called ill-posed inverse problem. It is reasonable to use prior knowledge of the force in order to develop more suitable reconstruction strategies and to increase accuracy. An impact event is characterized by a short time duration and a spatial concentration. Moreover the force time history of an impact has a specific shape, which also can be taken into account. In this contribution these properties of the external force are employed to create a sample-force-dictionary and thus to transform the ill-posed problem into a sparse recovery task. The sparse solution is acquired by solving a minimization problem known as basis pursuit denoising (BPDN). The reconstruction approach shown here is capable to estimate simultaneously the magnitude of the impact and the impact location, with a minimum number of accelerometers. The possibility of reconstructing the impact based on a noisy output signal is first demonstrated with simulated measurements of a simple beam structure. Then an experimental investigation of a real beam is performed.