• Advances in materials Research
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• v.8 no.3
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• pp.179-196
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• 2019

This paper researches static and dynamic bending behaviors of a crystalline nano-size shell having pores and grains in the framework of strain gradient elasticity. Thus, the nanoshell is made of a multi-phase porous material for which all material properties on dependent on the size of grains. Also, in order to take into account small size effects much accurately, the surface energies related to grains and pores have been considered. In order to take into account all aforementioned factors, a micro-mechanical procedure has been applied for describing material properties of the nanoshell. A numerical trend is implemented to solve the governing equations and derive static and dynamic deflections. It will be proved that the static and dynamic deflections of the crystalline nanoshell rely on pore size, grain size, pore percentage, load location and strain gradient coefficient.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.13 no.6
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• pp.490-496
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• 2001

An experimental study on the behavior of the water hold-up by condensation of a fin-and-tube heat exchanger with regard to the surface characteristics, i.e., contact angle, was conducted. The static and dynamic contact angles were measured, and condensation experiments were conducted. Flow patterns on the fins with different surface characteristics were visualized. Results showed that the static contact angle is proportional to the dynamic contact angle within the range of this study. The water hold-up of the heat exchanger increases as the static or dynamic contact angle of its surfaces increases. Existence of transition of flow patterns was found as the static or dynamic angle increase. Due to the transition in the flow patterns, changes in the gradient of the water hold-up is occurred around the static angle of 8$0^{\circ}C$.

• Journal of the korean Society of Automotive Engineers
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• v.15 no.1
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• pp.107-119
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• 1993

The objective of this study is to analyze the static and dynamic characteristics of automotive rubber components by computer simulation. Bush / rectangular type engine mounts and wind shield weather strip are analyzed by using the commercial code ABAQUS and the results are verified by experiments. Large deformation static response is analyzed in order to get the information about the deformation pattern and static stiffness of engine mounts, and about the seperation force of wind shield weather strip from body. The isothermal steady-state dynamic response of components which have been subjected to an initial static pre-load is analyzed for the dynamic stiffness of engine mount rubber components. There are good agreements between simulation and experiments. So it is possible to apply the computer simulation to the design of automotive rubber components.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.33 no.12
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• pp.1401-1409
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• 2009

All the forces in the real world act dynamically on structures. Design and analysis should be performed based on the dynamic loads for the safety of structures. Dynamic (transient or vibrational) responses have many peaks in the time domain. Topology optimization, which gives an excellent conceptual design, mainly has been performed with static loads. In topology optimization, the number of design variables is quite large and considering the peaks is fairly costly. Topology optimization in the frequency domain has been performed to consider the dynamic effects; however, it is not sufficient to fully include the dynamic characteristics. In this research, linear dynamic response topology optimization is performed in the time domain. First, the necessity of topology optimization to directly consider the dynamic loads is verified by identifying the relationship between the natural frequency of a structure and the excitation frequency. When the natural frequency of a structure is low, the dynamic characteristics (inertia effect) should be considered. The equivalent static loads (ESLs) method is proposed for linear dynamic response topology optimization. ESLs are made to generate the same response field as that from dynamic loads at each time step of dynamic response analysis. The method was originally developed for size and shape optimizations. The original method is expanded to topology optimization under dynamic loads. At each time step of dynamic analysis, ESLs are calculated and ESLs are used as the external loads in static response topology optimization. The results of topology optimization are used to update the design variables (density of finite elements) and the updated design variables are used in dynamic analysis in a cyclic manner until the convergence criteria are satisfied. The updating rules and convergence criteria in the ESLs method are newly proposed for linear dynamic response topology optimization. The proposed updating rules are the artificial material method and the element elimination method. The artificial material method updates the material property for dynamic analysis at the next cycle using the results of topology optimization. The element elimination method is proposed to remove the element which has low density when static topology optimization is finished. These proposed methods are applied to some examples. The results are discussed in comparison with conventional linear static response topology optimization.

• Bulletin of the Korean Chemical Society
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• v.27 no.12
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• pp.2002-2010
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• 2006

This study examined the quenching of ofloxacin (OFL) and flumequine (FLU) fluorescence by $Cuj^{2+}$, $Ni^{2+}$, $Co^{2+}$ and $Mn^{2+}$ in an aqueous solution. The change in the fluorescence intensity and lifetime was measured at various temperatures as a function of the quencher concentration. According to the Stern-Volmer plots, the fluorescence emission was quenched by both collisions (dynamic quenching) and complex formation (static quenching) with the same quencher but the effect of static quenching was larger than that of dynamic quenching. Large static and dynamic quenching constants for both OFL and FLU support significant ion-dipole and orbital-orbital interactions between fluorophore and quencher. For both molecules, the static and dynamic quenching constants by $Cu^{2+}$ were the largest among all the metal quenchers examined in this study. In addition, both the static and dynamic quenching mechanisms by $Cu^{2+}$ were somewhat different from the quenching caused by other metals. Between $Ni^{2+}$ and FLU, a different form of chemical interaction was observed compared with the interaction by other metals. The change in the absorption spectra as a result of the addition of a quencher provided information on static quenching. With all these metals, the static quenching constant of FLU was larger than those of OFL. The fluorescence of OFL was quite insensitive to both the dynamic and static quenching compared with FLU. This property of OFL can be explained by the twisted intramolecular charge transfer in the excited state.

• Journal of the Korean Society of Physical Medicine
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• v.19 no.2
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• pp.1-16
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• 2024

PURPOSE: This study examined the effects of four weeks of gaze stabilization exercises and balance training on the static and dynamic balance functions. METHODS: The study was an assessor-blinded randomized controlled trial conducted at Daegu University in South Korea. Thirty subjects who fulfilled the inclusion criteria were selected and divided randomly into three groups containing ten each. The first group received balance exercises with gaze stabilizing exercises (BGG). The second group received a balance exercise (BEG), and the third group received gaze-stabilizing exercise (GEG). Each group exercised for 40 minutes, three times a week for four weeks. The subjects were asked to complete the following static balance test: 1) one-leg standing test, 2) sharpened Romberg test, dynamic balance test, 3) Y-balance test, and 4) single-leg stand-squat-stand test. The static and dynamic balance were measured before and after four weeks to determine the effect of exercise on balance. RESULTS: The static (OLS and SRT) and dynamic (YBT and SST) balance tests showed significant differences in the surface and length of the three groups (p < .05), and the y-balance score effect size, 11.477 (p < .05), was improved significantly. On the other hand, the change in BGG value was larger than those of BEG and GEG, and the improvements in balance control were the most significant. CONCLUSION: After four weeks of exercise, BGG showed the best improvement in static and dynamic balance, suggesting that this specific type of gaze stabilization exercise with balance exercise may benefit healthy young adults.

• Journal of Korean Physical Therapy Science
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• v.15 no.2
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• pp.33-40
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• 2008

Background: The purpose of this study is to examine the effect of resistance exercise on static and dynamic proprioception by applying elastic bands to the knee flexor, which can be performed earlier than proprioception, a weight bearing pattern. Proprioceptive training may be applied to the early period of recuperation training along with resistance exercise to prevent damage to the knees and the joints in the lower body, as well as the reoccurrence of injury, which is expected to improve the effect of static and dynamic proprioceptive training. Methods: The subjects of this study were 32 men and women in their 20s who volunteered to participate in the experiment which was carried out over the course of 6 weeks from March 14 to April 24 at K Hospital located in Yongin City. They were tested in two groups: the elastic band resistance exercise group (RE: Resistance Excercise Group, n＝17) and the joint motion range exercise group(ROM: Range of Motion Group, n＝15). In this experiment, static and dynamic proprioceptive tests were given to both groups before and after the test. In this study, SPSS Win ver.12.0 was utilized to perform a T-test on the independent samples in order to validate the identical features of subjects in the RE and ROM Group and substantiate the significance as to the difference between both groups before and after the test. Also, a paired T-test was conducted to compare the static and dynamic proprioception of both groups before and after the test. The statistical significance levels were ${\alpha}$＝.05. Results: 1.The static proprioception in both groups, RE and ROM, increased in a statistically significant way after the test(p<.05). 2.The static propriocetion of the RE group increased in a statistically significant way after the test(p<.05). However, the increase of the static proprioception in the ROM group was not statistically significant. 3.Static and dynamic proprioception of the RE group increased significantly more than that of the ROM group after the test(p<.05). Conclusion: The resistance exercise using elastic bands improved the static and dynamic proprioception more than the joint motion range exercise did, reducing the risk of injury by enhancing the location sense of the joints and the sense of motion and shortening the period of recovery from injury. The outcome of the experiment may provide basic data for developing an effective way to reduce the risk of injury among ordinary people and athletes.

• Earthquakes and Structures
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• v.23 no.4
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• pp.353-361
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• 2022

The dynamic behavior of a single pile was investigated by using analytical and numerical studies. The focus of this study was to develop the dynamic p-y curve of a pile for pseudo-static analysis considering the shear wave velocity of the soil by using three-dimensional numerical analyses. Numerical analyses were conducted for a single pile in dry sand under changing conditions such as the shear wave velocity of the soil and the acceleration amplitudes. The proposed dynamic p-y curve is a shape of hyperbolic function that was developed to take into account the influence of the shear wave velocity of soil. The applicability of pseudo-static analysis using the proposed dynamic p-y curve shows good agreement with the general trends observed by dynamic analysis. Therefore, the proposed dynamic p-y curve represents practical improvements for the seismic design of piles.

• Physical Therapy Korea
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• v.29 no.1
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• pp.19-27
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• 2022

Background: Foot drop is a common symptom in stroke patients. Tape applications are widely used to manage foot drop symptoms. Previous studies have evaluated the effects of static and dynamic balance and gait on foot drop using kinesiology tape; however, only few studies have used dynamic tape application in stroke patients with foot drop. Objects: The purpose of this study was to investigate the immediate effects of dynamic taping, which facilitates the dorsiflexor muscle, on static and dynamic balance and gait speed in stroke patients with foot drop. Methods: The study included 34 voluntary patients (17 men, 17 women) with stroke. The patients were randomly assigned to the experimental group (n = 17), wherein dynamic taping was used to facilitate the dorsiflexor muscle, or the control group (n = 17), wherein kinesiology taping was used. Before the taping application, velocity average, path-length average, Berg balance scale, and timed up and go test (TUG) were recorded to measure static and dynamic balance, whereas the 10-meter walk test (10MWT) was used to measure gait speed. After the taping application, these parameters were re-evaluated in both groups. Repeated measure analysis of variance was used. Statistical significance levels were set to α = 0.05. Results: Except for the 10MWT scores in the control group, significant differences were noted in all the parameters measured for static and dynamic balance and gait speed between the pre and post-test (p < 0.05). However, the parameters showed significant interaction effects between group and time in the TUG and 10MWT (p < 0.01). Conclusion: These results indicate that compared with kinesiology taping, dynamic taping used in chronic stroke patients with foot drop had a more significant effect on dynamic balance and gait speed.

• International Journal of High-Rise Buildings
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• v.4 no.1
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• pp.27-37
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• 2015

Structural health monitoring is becoming more and more important in the domain of civil engineering as a proper mean to increase and maintain the safety, especially in the land of earthquakes like Japan. In many civil structures, the deformations are the most relevant parameter to be monitored. In this context, a monitoring technology based on the use of long-gage fiber optic deformation sensor, SOFO is being applied to a 33-floors tall building in Tokyo. Sensors were installed on the $2^{nd}$ floor's steel columns of the building on May 2005 in the early stage of the construction. The installed SOFO sensors were dynamic compatible ones which enable both static and dynamic measurements. The monitoring is to be performed during the whole lifespan of the building. During the construction, static deformations of the columns had been measured on a regular basis using a reading unit for static measurement and dynamic deformation measurements were occasionally conducted using a reading unit for dynamic measurement. The building was completed on August 2006. After the completion, static and dynamic deformation measurements have been continuing. This paper describes a health monitoring technology, SOFO system which is applicable to high-rise buildings and monitoring results of a 33-floors tall building in Tokyo from May 2005 to October 2010.