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This paper proposes a modeling technique which is able to not only reliably and easily represent the hysteretic characteristics but also analyze the dynamic stress of a taper leaf spring. The flexible multi-body dynamic model of the taper leaf spring is developed by interfacing the finite element model and computation model of the taper leaf spring. Rigid dummy parts are attached at the places where a finite element leaf model is in contact with an adjacent one in order to apply contact model. Friction is defined in the contact model to represent the hysteretic phenomenon of the taper leaf spring. The test of the taper leaf spring is conducted for the validation of the reliability of the flexible multi-body dynamic model of the taper leaf spring developed in this paper. The test is started at an unloaded state with the excitation amplitude of $1{\sim}2mm/sec$ and frequency of 132 mm. First, the simulation is conducted with the same condition as the test. Then, the simulations are conducted with various amplitudes in a loaded state. The hysteretic diagram from the test is compared with the ones from the simulation for the validation of the reliability of the model. The dynamic stress analysis of the taper leaf spring is also conducted with the developed flexible multi-body dynamic model under a dynamic loading condition.

무어링이 있는 플로팅 건물의 응답을 확인하기 위하여 수조실험을 수행하고 수치해석과 비교하였다. 사용 모델의 폰툰 길이는 1.8m, 폭은 0.6m, 높이는 0.2m로 알루미늄판을 이용하여 제작하였으며 폰툰 위에 고유주파수가 1.57과 2.4Hz 되는 상부골조를 설치하였다. 계류의 특성을 반영하기 위하여 500 및 1,000 N/m 강성의 스프링을 사용하였다. 실험에 따른 폰툰의 X(길이방향)와 RY(길이방향에 직각방향의 회전)은 파랑하중이 장주기파로 갈수록 가속도가 작게 나타났다. 또한 수평방향의 스프링 계류의 구속력 때문에 계류 강성이 클수록 작은 가속도 응답을 나타냈다. 상부골조의 가속도는 폰툰의 X가속도, RY가속도에 비례하여 증가하는 양상을 나타내었다. 폰툰의 X가속도와 RY가속도 시간이력을 이용하여 상부골조의 지반가속도로 치환한 부분골조해석법은 상부골조의 가속도가 실험갑과 근사한 값을 나타내었다.

To compare the response of a floating pontoon with mooring, model tests in the basin are carried out and numerical analysis are executed. A pontoon model is designed with length of 1.8m, width of 0.6m, depth of 0.2m with aluminum plate and spring is used to simulate the mooring effect. And a one storied framed building is built on the pontoon, of which natural period can be varied 1.57 or 2.4Hz. The spring mooring system which had stiffness 500 and 1000N/m was used to prevent drift of floating structure. As the result of the experiment, the acceleration response of pontoon and superstructure was decreased when wave period became longer. X(longitudinal direction) and RY (rotation in perpendicular to longitudinal direction)acceleration of pontoon was increased when the natural frequency of superstructure became lower, and the length of wave was shorter. From the comparison of the response of building with analysis methods, the substructure analysis method using base input acceleration which wad obtained from surge and rolling acceleration shows a good correspondence.

The recently research shows that the many tourists of Suanbo hot spring waters haven’t satisfied the service. These reasons due to that they did not properly consider the satisfaction of tourists’ services and index. However, satisfaction level of hot spring waters tourists is interacted complicatedly with various factors, the interactions are not easily identified. A structural equations model is adopted to capture the complex relationships among variables. In the model estimation, we used 140 survey data of Suanbo hot spring waters tourists. The SEM with several factors mentioned above as exogenous variables shows that they have complex and strong relationships. As results of a SEM, it was shown that variables influencing in pleasance are surrounding scenery, clean condition inside hot springs and congestion for use in satisfaction level most. Secondly, in case of kindness, attitudes of employees influence in satisfaction level most, followed by attitudes of residents and kindness of employees. Thirdly, in case of information, it was shown guidance on internal roads influencing in satisfaction level most, followed by guidance on owner drivers, guidance on surrounding tourist attractions and guidance on public transportation. Finally, a variable influencing in accessibility most is satisfaction level of public transportation.

Spring model for enzyme deformation is proposed for the calculation of residual force as a new mechanical approach. This new modeling method assumes that enzyme moves like elastic body doing substrate docking and product release. It was validated by selection of forced and twisted region in cases of HIV-1 protease and bacteriophage T4 lysozyme. Enzyme flexibility has relation to enzyme activity because enzyme does flexible motion for catalysis. The selected regions using spring model were compared with activity-enhanced mutation regions in bacteriophage T4 lysozyme and Candida antarctica lipase B. It was found that the mutations at the helix edges located far away from twisted region increased enzyme activity in T4 lysozyme. In case of Candida antarctica lipase B, mutations at the most twisted region make enzyme activity increase. It will be discussed about relationship between enzyme flexibility and activity based on these data.

Needle insertion is the most common procedure of minimally invasive interventions. During insertion into a soft tissue, the needle with bevel tip can deflect due to the asymmetric forces acting on the tip of the needle. In this paper, a mechanics-based model is developed to predict the needle deflection. In the model, the needle is considered as a cantilever beam supported by a series of nonlinear springs each of which has stiffness different from each other. The value of stiffness can be calculated by cutting force acting on the needle tip. Based on the model and the analysis of cutting force and friction force, Rayleigh-Ritz method is used to estimate the amount of needle deflection. Experiment shows that the simulation model can accurately predict the deflection of the bevel-tipped needle.

In order for small electric vehicles to drive on hilly roads in Korea, methods to improve the climbing ability and power performance of vehicles should be taken. In order to improve the power performance of small electric vehicles, the performance of motors mounted on electric vehicles should be improved. However, if the performance of the motor is improved to improve the power performance of the electric vehicle, it is possible to lower the price competitiveness accordingly. In addition, the power consumption of the battery is rapidly increased to drive the high-performance motor, so in order to introduce the small electric vehicle into the domestic market, various problems must be overcome. In order to commercialize small electric vehicles that do not emit harmful exhaust gases to the human body in the hilly domestic terrain, it is effective to introduce a separate continuously variable transmission system that can improve the climbing ability and power transmission ability. In this study, we propose a proprietary model of continuously variable transmissions that can be applied to small electric vehicles. The proposed continuously variable transmission is equipped with a spring in the driving pulley and the driven pulley, and has the advantage of performing a shift that increases torque in a situation where the vehicle needs to increase torque when driving on a hill. In addition, the basic design for commercialization of the proposed continuously variable transmission was carried out, and the prototype manufactured and attached to the body of a small electric vehicle.

1995년 국내 먹는샘물 판매 허용 이후, 국내 먹는샘물 시장은 지속적인 성장을 이루어 왔다. 먹는샘물 사업은 엄격한 환경 규제에 따른 지역 내 다양한 갈등문제를 발생시키는 한편, 사업 추진에 따른 지역 이미지 제고, 지역주민 고용효과 등 긍정적인 효과를 동시 에 발생시키고 있다. 따라서 효율적인 먹는샘물 사업의 추진을 위해서는 사전에 먹는샘 물 사업 추진에 따른 사회적 비용과 경제적 편익을 동시에 고려하여야 한다. 이에 본 연구는 먹는샘물 사업에 관한 정책 수립을 위한 기초 연구로서, 먹는샘물 사업 의 경제적 편익을 측정하기 위한 모형을 개발하는 것을 목적으로 한다. 이를 위하여 본 연구에서는 먹는샘물 사업의 사업구조를 구체적으로 분석하고, 먹는샘물 사업을 독립화 한 지역산업연관표를 구축하였다. 구체적으로는 2021년 기준 국내 먹는샘물 시장 점유율 42%를 차지하고 있는 제주 삼다수사업의 중간재 매입자료를 활용하여, 먹는샘물 사업의 사업구조를 분석하고, 이를 토대로 먹는샘물 사업을 독립화한 지역산업연관표와 분석모 형을 개발하였다. 아울러, 개발된 분석모형을 활용하여 먹는샘물 사업의 지역경제효과를 분석·제시하였다. 이러한 먹는샘물 사업의 지역경제효과 분석모형을 토대로 분석한 지역 경제효과 결과는, 향후 지역단위에서 먹는샘물 사업 추진 시 경제적 편익을 추정하는 데 객관적인 기초자료로서 활용될 수 있다.

Since domestic drinkable spring water sales were legalized in 1995, the domestic drinkable spring water market has continued to grow. These businesses create various conflicts within the region because of strict environmental regulations, while simultaneously generating positive effects, such as improving the local image and creating local employment. To efficiently promote drinkable spring water businesses, the social costs and economic benefits of promoting them should be considered in advance. As a basic study for establishing policies regulating drinkable spring water businesses, this study aims to develop a model to measure their economic benefits. This study specifically analyzed the business structure of a drinking spring water business, and constructed a regional input-output table that was independently developed using such businesses. Specifically, the business structure was analyzed using data of purchased intermediary goods from the Jeju Samdasoo Business, which accounts for a 42% share of the domestic drinkable spring water market as of 2021, and the regional input-output model was developed. In addition, using this analytic model, the regional economic ripple effect of drinking spring water businesses was analyzed and presented. The results of the analysis of this effect can be used as objective basic data to estimate economic benefits when promoting drinkable spring water businesses at the local level.

불연속 암반의 거동을 모사하기 위해 개별요소법(Discrete Element Method, DEM)이 널리 활용되고 있으나, 접촉 응답을 계산하는 방식에 따라 해석 결과의 수치적 안정성, 접촉 이력 재현성 및 계산 효율성은 달라질 수 있다. 본 연구에서는 DEM의 대표적인 접촉 해석 기법인 Spring model과 Impulse-based method를 대상으로, 동일한 해석 조건에서 시간 간격 변화에 따른 수치 응답 특성을 비교·분석하였다. 이를 위해 정적 접촉, 준정적 전단, 회전 및 동적 충돌 조건을 설정하고, 접촉력, 전단저항, 속도, 위치 및 에너지 응답을 비교하였다. 해석 결과, Spring model은 정적 접촉 및 준정적 전단 조건에서 접촉력 변화와 전단저항의 점진적 발현을 재현하는 데 유리하였으나, 시간 간격 증가에 따라 접촉력 진동, 에너지 응답 왜곡 및 발산이 나타났다. 반면, Impulse-based method는 회전 및 동적 충돌 조건에서 상대적으로 큰 시간 간격에서도 안정적인 운동 응답을 보였으나, 접촉 이력에 기반한 준정적 전단 거동을 재현하는 데에는 제한이 있었다. 두 기법의 접촉 계산 방식의 차이는 시간 간격 변화에 대한 민감성의 차이로 나타났으며, 이는 해석의 초점이 접촉 이력에 있는지, 운동량 변화에 있는지에 따라 각 기법의 적합성을 가르는 요인이 된다. 향후 Impulse-based method의 한계를 보완하는 연구가 수행된다면, 계산 효율성을 유지하면서 절리 암반 해석으로 적용 범위를 확장할 수 있을 것으로 기대된다.

The discrete element method (DEM) is widely used to simulate the mechanical behavior of discontinuous rock masses; however, the numerical stability, reproducibility of contact history, and computational efficiency of the analysis can vary depending on the contact calculation method adopted. In this study, two representative DEM contact formulations, the spring model and the impulse-based method, were comparatively analyzed in terms of their numerical response to variations in the timestep under identical simulation conditions. To this end, static contact, quasi-static shear, rotational, and dynamic impact conditions were considered, and the contact force, shear resistance, velocity, position, and energy responses were compared. The results show that the spring model effectively reproduces the gradual mobilization of contact force and shear resistance under static contact and quasi-static shear conditions, but exhibits contact force oscillation, distortion of the energy response, and divergence as the timestep increases. In contrast, the impulse-based method maintains a stable kinematic response even at relatively large timesteps under rotational and dynamic impact conditions, yet shows limitations in reproducing the quasi-static shear behavior that relies on contact history. The difference in the contact calculation schemes of the two methods manifests as a difference in their sensitivity to the timestep, which in turn determines the suitability of each method depending on whether the analysis focuses on contact history or momentum change. These findings suggest that, if future studies address the limitations of the impulse-based method, its application can be extended to jointed rock mass analysis while preserving its computational efficiency.

The analysis of fluid-structure interaction (FSI) in storage tanks is a fundamental aspect of structural design, particularly in spherical tanks used for water storage. Numerical methods implemented in finite element software are commonly employed to address this phenomenon. These methods are typically based on complex formulations that integrate fluid dynamics, providing detailed and accurate results. However, in structural design, engineers often prefer simplified models that adequately capture the essence of the problem without requiring complex simulations. This research aims to validate the modeling approach of FSI in spherical storage tanks using a mechanical-equivalent mass-spring model (MEMSM). The impulsive and convective components of the fluid were represented as lumped masses and springs whose stiffness is associated with the oscillation of the convective component. A perfectly fixed base was assumed, neglecting effects of soil-structure interaction (SSI), to remain consistent with experimental conditions used for validation. The model was validated by comparing the natural vibration frequencies, and the results indicate that the MEMSM model predicts these frequencies with a difference of 1.3% for the impulsive component and a maximum difference of 6.7% for the convective component. This result validates the proposed approach and underscores its main contribution: providing an alternative, efficient, and easily implementable tool for the dynamic analysis of spherical tanks, suitable for early stages of structural design without compromising accuracy.

This paper deals with the behavior of fresh concrete that is under vibration using mass-spring model (MSM). To this end, behaviors of two different full scale precast concrete molds were investigated experimentally and theoretically. Experiments were performed under vibration with the use of a computer-based data acquisition system. Transducers were used to measure time-dependent lateral displacements at some points on mold while mold is empty and full of fresh concrete. Analytical modeling of molds used in experiments were prepared by three dimensional finite element method (3D FEM) using software. Modeling of full mold, using MSM, was made to solve the problem of dynamic interaction between fresh concrete and mold. Numerical displacement histories obtained from time history analysis were compared with experimental results. The comparisons show that the measured and computed results are compatible.

This paper is a study on the experiment and elasto-plastic discrete limit analysis of reinforced concrete circular cylindrical shell by the rigid-bodies spring model. In the rigid bodies-spring model, each collapsed part or piece of structures at the limiting state of loading is assumed to behave like rigid bodies. The present author propose new discrete elements for elasto-plastic analysis of cylindrical shell structures, that is, a rectangular-shaped cylindrical element and a rhombus-shaped cylindrical element for the improvement and expansion of this rigid-bodies spring model. In this study, it is proposed how this rigid element-bodies spring model can be applied to the elasto-plastic discrete limit analysis of cylindrical shell structures. Some numerical results of elasto-plastic discrete limit analysis and experimental results such as the curve of load-displacement and the yielding and fracturing pattern of circular cylindrical shell under horizontal load are shown.

Since large-scale commercial wind turbine generator systems such as MW-class wind turbines are becoming widely operated, the vibration and distortion of the blade are becoming larger and larger. Therefore the soft structure design instead of the solid-design is one of the important concepts to reduce the structural load and the cost of the wind turbine rotors. The objectives of the study are development of the fluid-structure coupled analysis code and evaluation of soft rotor-blade design to reduce the unsteady structural blade load. In this paper, fluid-structure coupled analysis for the HAWT rotor blade is performed by free wake panel method coupled with hinge-spring blade model for the flapwise blade motion. In the model, the continuous deflection of the rotor blade is represented by flapping angle of the hinge with one degree of freedom. The calculation results are evaluated by comparison with the database of the NREL unsteady aerodynamic experiment. In the analysis the unsteady flapwise moments in yawed inflow conditions are compared for the blades with different flapwise eigen frequencies.

Among the various aspects of offline handwritten character patterns, it is the great variety of writing styles and variations that renders the task of computer recognition very hard. The immense variety of character shape has been recognized but rarely studied during the past decades of numerous research efforts. This paper tries to address the problem of measuring image distortions and handwritten character patterns with respect to reference patterns. This work is based on mass-spring mesh model with the introduction of simulated electric charge as a source of the external force that can aid decoding the shape distortion. Given an input image and a reference image, the charge is defined, and then the relaxation procedure goes to find the optimum configuration of shape or patterns of least potential. The relaxation process is based on the fourth order Runge-Kutta algorithm, well-known for numerical integration. The proposed method of modeling is rigorous mathematically and leads to interesting results. Additional feature of the method is the global affine transformation that helps analyzing distortion and finding a good match by removing a large scale linear disparity between two images.

Hot Spring Law of Taiwan was passed in legislative assembly on 3 June 2003. Hot springs would become one of the most important natural resources for recreation purposes. Both public and private sectors will invest large amount of capital in this area in the near future. The value of remote sensing technology is to give a critical tool for observing the landscape to find out mega-scaled geological structures, which may not be able to be found by conventional approaches. The occurrences of the hot springs in Taiwan are mostly in metamorphic and sedimentary rocks , other than in volcanic environments. Local geothermal anomaly or heat of springs transfer by liquid convection other than conduction or radiation. The deeply -seated fractures of hard rocks are the conduit of the convection of hot water, which could be as deep as 3000 meters in a hypothetical model of Taiwan. Clues to find outcrops of hot spring can be obtained by a structure-controlled model deduced by geological lineaments observed by satellite images and stereoscopic interpretation of aerial photographs. A case study conducted in Eastern Taiwan will be demonstrated.

This paper presents a simple method to control the motion of a quadruped robot in unknown rough terrain using a full dynamic model. First, using the stiffness control method, the behavior of the four legs is approximated using four 3D spring damper systems. In this way, the dynamic model can be derived in Cartesian space. Based on this model, a control strategy is proposed to preserve the asymptotical stability of the system. In addition, a reflex motion control is introduced to cope with the rotational disturbance of the robot body. Finally, dynamic simulations and experiments of a quadruped walking robot were performed on unknown rough terrain to verify the proposed method.

The paper presents a numerical study to evaluate the phase velocities and attenuations of the average longitudinal and shear ultrasonic waves resulting from multiple scattering in fiber-reinforced composites. A computational procedure developed in this work is first used to produce a random, yet largely even distribution of fibers. Both the viscoelastic epoxy matrix and lossless randomly distributed graphite fibers are modeled using the mass-spring-dashpot lattice model, with no damping for the latter. By numerically simulating ultrasonic through-transmission tests using this direct model of composites, phase velocities and attenuations of the longitudinal and shear waves through the composite are found as functions of frequency or fiber concentration. The numerical results are observed to generally agree with the corresponding results in the literature. Discrepancies found in some detail aspects, particularly in the attenuation results, are also addressed.

A new 5-MW floating offshore wind turbine moored by a spring-tensioned-leg was proposed for installation in about 50m water depth. Its substructure is a platform of the inverted conical cylinder type with massive ballast weight plate at the bottom. A 1:128 scale model was built for the preliminary engineering development. The model tests in waves and wind were carried out to estimate motion characteristics of this platform in the Ocean Engineering Wide Tank of the University of Ulsan. Its motions were measured and the RAOs were compared. The proposed floating offshore wind turbine showed a good stability and decent responses in waves, wind and operation of the wind turbine.