• Tunnel and Underground Space
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• v.8 no.3
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• pp.184-193
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• 1998

In order to dispose radioactive wastes safely, it is needed to understand the mechanical, thermal, fluid behavior of rockmass and physico-chemical interactions between rockmass and water. Also, the knowledge about mechanical and hydraulic properties of rocks is required to predict and to model many conditions of geological structure, underground in-situ stress, folding, hot water interaction, intrusion of magma, plate tectonics etc. This study is based on researches about rock mechanics issues associated with a waste disposal in deep rockmass. This paper includes the mechanical and hydraulic behavior of rocks in varying temperature conditions, thermo-hydro-mechanical coupling analysis in rock mass and deformation behavior of discontinuous rocks. The mechanical properties were measured with Interaken rock mechanics testing systems and hydraulic properties were measured with transient pulse permeability measuring systems. In all results, rock properties were sensitive to temperature variation.

• International Journal of Fluid Machinery and Systems
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• v.6 no.2
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• pp.75-86
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• 2013

The effects of acoustic resonance and volute geometry on phase resonance are studied theoretically and experimentally using a centrifugal fan. One dimensional theoretical model is developed taking account of the reflection from the discharge pipe end. It was found that the phase resonance occurs, even with the effects of acoustic resonance, when the rotational speed of rotor-stator interaction pattern agrees with the sound velocity. This was confirmed by experiments with and without a silencer at the discharge pipe exit. The pressure wave measurements showed that there are certain effects of the cross-sectional area change of the volute which is neglected in the one dimensional model. To clarify the effects of area change, experiments were carried out by using a ring volute with a constant area. It was demonstrated that the phase resonance occurs for both interaction modes travelling towards/away from the volute. The amplitude of travelling wave grows towards the volute exit for the modes rotating towards the volute exit, in the same direction as the impeller. However, a standing wave is developed in the volute for the modes rotating away from the volute exit in the opposite direction as the impeller, as a result of the interaction of a growing wave while travelling towards the tongue and a reflected wave away from the tongue.

• Journal of Ocean Engineering and Technology
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• v.28 no.2
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• pp.126-132
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• 2014

In this study, a method for analyzing the collision and interaction between ice bergy bits and a Mark III type liquid natural gas (LNG) carrier was considered, and the structural safety of a ship's hull and cargo containment system (CCS) was evaluated. In the analysis, a constitutive model implementing the strain rate dependant mechanical property was used to consider the typical material characteristics of ice rationally. A relatively simple and easy ice structure interaction analysis procedure, compared with the accurate but complicated FSI analysis scheme, was suggested. When the ice bergy bits collided with ship's side hull under the four assumed scenarios, the structural behaviors of the ship structure and LNG CCS were simulated by applying the suggested ice collision analysis procedure using the commercial hydro-code LS-DYNA. In addition, the effects of the shapes and colliding speed of the ice bergy bits on the ice-structure interaction and safety of the CCS were examined in detail.

• Journal of the Ergonomics Society of Korea
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• v.31 no.4
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• pp.515-523
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• 2012

Objective: The aim of this study is to investigate users' intuitive stereotypes on non-touch gestures and establish the gesture dictionary that can be applied to gesture-based interaction designs. Background: Recently, the interaction based on non-touch gestures is emerging as an alternative for natural interactions between human and systems. However, in order for non-touch gestures to become a universe interaction method, the studies on what kinds of gestures are intuitive and effective should be prerequisite. Method: In this study, as applicable domains of non-touch gestures, four devices(i.e. TV, Audio, Computer, Car Navigation) and sixteen basic operations(i.e. power on/off, previous/next page, volume up/down, list up/down, zoom in/out, play, cancel, delete, search, mute, save) were drawn from both focus group interview and survey. Then, a user participatory design was performed. The participants were requested to design three gestures suitable to each operation in the devices, and they evaluated intuitiveness, memorability, convenience, and satisfaction of their derived gestures. Through the participatory design, agreement scores, frequencies and planning times of each distinguished gesture were measured. Results: The derived gestures were not different in terms of four devices. However, diverse but common gestures were derived in terms of kinds of operations. In special, manipulative gestures were suitable for all kinds of operations. On the contrary, semantic or descriptive gestures were proper to one-shot operations like power on/off, play, cancel or search. Conclusion: The touchless gesture dictionary was established by mapping intuitive and valuable gestures onto each operation. Application: The dictionary can be applied to interaction designs based on non-touch gestures. Moreover, it will be used as a basic reference for standardizing non-touch gestures.

• Structural Engineering and Mechanics
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• v.78 no.2
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• pp.163-174
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• 2021

Track-bridge interaction has become an essential part in the design of bridges and rails in terms of modern railways. As a unique ballastless slab track, the longitudinal continuous slab track (LCST) or referred to as the China railway track system Type-II (CRTS II) slab track, demonstrates a complex force mechanism. Therefore, a comprehensive track-bridge interaction study between multi-span simply supported beam bridges and the LCST is presented in this work. In specific, we have developed an integrated finite element model to investigate the overall interaction effects of the LCST-bridge system subjected to the actions of temperature changes, traffic loads, and braking forces. In that place, the deformation patterns of the track and bridge, and the distributions of longitudinal forces and the interfacial shear stress are studied. Our results show that the additional rail stress has been reduced under various loads and the rail's deformation has become much smoother after the transition of the two continuous structural layers of the LCST. However, the influence of the temperature difference of bridges is significant and cannot be ignored as this action can bend the bridge like the traffic load. The uniform temperature change causes the tensile stress of the concrete track structure and further induce cracks in them. Additionally, the influences of the friction coefficient of the sliding layer and the interfacial bond characteristics on the LCST's performance are discussed. The systematic study presented in this work may have some potential impacts on the understanding of the overall mechanical behavior of the LCST-bridge system.

• The Korean Journal of Rheology
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• v.10 no.4
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• pp.202-216
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• 1998

Improved version of previous 'Orthotropic' closure approximation, termed 'ORW' has been numerically developed using new homogeneous flow data. Previous 'Orthotropic' closure approximation, i.e., ORF or ORL showed non-physical oscillation for interaction coefficient $C_1$<0.001 at simple shear flow. It also shows non-physcial oscillation and under-prediction compared with 'Distribution Function Calculation' at non-homogeneous flow of center-gated disk. These phenomena are mainly due to the flow data of 'Distribution Function Calculation' which were used for least-square optimization. ORW obtained by fitting flow data of low interaction coefficient does not show non-physical oscillation and results in reasonably good behaviors at non-homogeneous flows as well as homogeneous flows. Fitting function forms have not been found to improve overall behaviors. It has been found that considering all the eigenvalues of orientation tensor (including the third eigenvalues) might end up with a better closure approximation than just considering the first and second eigenvalues. It is, however, very important and yet difficult to select appropriate function forms of eigenvalues. Numerical simulation including coupling and in-plane velocity gradient effects were performed for injection mold filing process with a film-gated strip and a center-gated disk using ORW and various other closure approximations for comparisons. Although ORW is in excellent agreement with 'Distribution Function Calculation', the predicted results seem to have consistent error in comparison with experimental data. The diffusivity term with constant interaction coefficient might have to be further investigated in order to accurately describe orientation states.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.37 no.8
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• pp.953-960
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• 2013

This study aimed to investigate the penetration characteristics of a segmented penetrator with normal and inclined angles. The length to diameter ratio (L/D) of the segmented penetrator was varied as 1.0, 0.5, and 0.25. Moreover, impact velocities of 1.5, 2.0, and 2.5 km/s and inclination angles of $15^{\circ}$, $30^{\circ}$, and $45^{\circ}$ were successively applied. The AUTODYN-3D code was used to simulate the penetration performance of the segmented penetrator. The results show that the penetration performance of the segmented penetrator with steel plates was obviously higher than that of the corresponding continuous penetrator with steel plates. The outstanding penetration performance of the segmented penetrator can be observed when the impact velocity was 2.0 km/s and L/D = 1. In this case, the penetration performance of the segmented penetrator was 7% higher than that of the corresponding continuous penetrator. This trend was attributable to the interaction between the reactive plate and the projectile. The extent of the interaction relies on the relative velocities of the plate and projectiles, inclination angle, and number of segmented penetrators. It was proven that the penetration performance of the segmented penetrator can be improved by increasing the impact velocity, number of segmented penetrators between segments, and penetrator length.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.37 no.9
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• pp.807-814
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• 2013

A fundamental study on laser-tissue interaction was conducted with the aim of developing a therapeutic medical device that can remove lesions on the intestinal wall by irradiating a high-power 808-nm infrared laser light incorporated in an endoscopic system. The perforation depth was linearly increased in the range of 1~4 mm in proportional to laser output (3~12 W) and irradiation time (5~20 s). We demonstrated that the perforation depth during laser irradiation was varied according to the tissue property of each extracted porcine organ. The measurement of the temperature distribution suggests that the energy is localized in the irradiation spot and transferred to deep tissue, which protects the surrounding tissue from thermal injury. These results can be used to set the driving parameters for a laser incision technique as an alternative to conventional surgical interventions.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.1
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• pp.45-51
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• 2021

The purpose of this study was to investigate the effect of applying whole body vibration exercise at 30 Hz on the thickness and mechanical properties of the erector spinae. The study population included 24 adults (11 male and 13 female) in the N region. The subjects were divided into two groups, a 30Hz whole body vibration exercise(WG, n=12) and an LSG(12 subjects). Changes in the thickness and mechanical properties of the erector spinae were analyzed before the exercises and after four and eight weeks of exercises using a two-way repeated analysis of variance with a statistical significance level of α=0.05. When there was an interaction between the groups and measurement times, post hoc analyses were conducted at a statistical significance level of α=0.01. The thickness, frequency, stiffness and strain of the erector spinae muscles were significantly different in each time period and in the interaction between time period and the group (P<0.05), and recovery was significantly different only in each time period (P<0.05). Thus, 30Hz whole body vibration exercise had a positive effect on the thickness and mechanical properties of the erector spinae. The results of this preliminary study suggest that whole body vibration exercise may find a place as a lumbar stabilization exercise in clinical practice in the future.

• Particle and aerosol research
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• v.9 no.4
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• pp.261-269
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• 2013

The chemical mechanical polishing (CMP) process is widely used in semiconductor manufacturing process for planarization of various materials and structures. Point-of-use (POU) filters are used in most of the CMP processes in order to reduce the unwanted micro-scratches which may result in defects. The performance of the POU filter is depends on type and size of the abrasives used during cleaning process. For this reason, there is a need to evaluate POU filters for their filtration efficiency (FE) with different types of abrasives. In this study, we developed filter test system to evaluate the FE of POU using ceria and silica abrasives (slurry). The POU filter is roll type capsule filter with retention size of 0.2 ${\mu}m$. Two POU filters of different make are evaluated for FE. We observed that both POU filters show similar filtration efficiency for silica and ceria slurry. Results reveal that the ceria slurry and the colloidal silica particle are removed not only by mechanical way but also hydrodynamic and electrostatic interaction way.