• Journal of Power System Engineering
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• v.21 no.5
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• pp.63-70
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• 2017

This paper deals with anti-pinch system based on current information which prevents some risks for trapping, squeezing or injury to people in smart window on vehicles. Automatic configuration of current threshold is suggested to recognize pinch states in the current based anti-pinch system. Also, some factors affecting to the squeezing force were analyzed by some experimental results and simulations. The validity of the suggested system was verified to satisfy the strengthened American safety regulation, FMVSS 118-S5, through some experimental results.

• Geomechanics and Engineering
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• v.29 no.1
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• pp.41-51
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• 2022

Tunneling in rocks having the time-dependent behavior, causes some difficulties like tunnel convergence and, as a result, pressure on concrete lining; and so instability on this structure. In this paper the time-dependent behaviour of squeezing phenomenon in a large cross section tunnel was investigated as a case study: Alborz tunnel. Then, time-dependent behaviour of Alborz tunnel was evaluated using FLAC2D based on the finite difference numerical method. A Burger-creep viscoelastic model was used in numerical analysis. Using numerical analysis, the long-time effect of squeezing on lining stability was simulated.This study is done for primary lining (for 2 years) and permanent lining (for 100 years), under squeezing situations. The response of lining is discussed base on Thrust Force-Bending Moment and Thrust Force-Shear Force diagrams analysing. The results determined the importance of consideration of time-dependent behaviour of tunnel that structural forces in concrete lining will grow in consider with time pass and after 70 years can cause instability in creepy rock masses section of tunnel. To show the importance of time-dependent behavior consideration of rocks, elastic and Mohr-Coulomb models are evaluated at the end.

• Tribology and Lubricants
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• v.39 no.6
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• pp.273-277
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• 2023

This paper presents a molecular dynamics simulation-based numerical investigation of the influence of surface energy on water lubrication. Models composed of a crystalline substrate, half cylindrical tip, and cluster of water molecules are prepared for a tribological-characteristic evaluation. To determine the effect of surface energy on lubrication, the surface energy between the substrate and water molecules as well as that between the tip and water molecules are controlled by changing the interatomic potential parameters. Simulations are conducted to investigate the indentation and sliding processes. Three different normal forces are applied to the system by controlling the indentation depth to examine the influence of normal force on the lubrication of the system. The simulation results reveal that the solid surface's surface energy and normal force significantly affect the behavior of the water molecules and lubrication characteristics. The lubrication characteristics of the water molecules deteriorate with the increasing magnitude of the normal force. At a low surface energy, the water molecules are readily squeezed out of the interface under a load, thus increasing the frictional force. Contrarily, a moderate surface energy prevents expulsion of the water molecules due to squeezing, resulting in a low frictional force. At a high surface energy, although squeezing of the water molecules is restricted, similar to the case of moderate surface energy, dragging occurs at the soil surface-water molecule interface, and the frictional force increases.

• The Korean Journal of Rheology
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• v.11 no.2
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• pp.82-90
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• 1999

Electrorheological(ER) fluid is a material that shows the dramatic change of rheological properties under an electric field and responds reversibly in a few milliseconds. ER fluid's response to an electric field along with its fast switching capability allows ER devices to be precisely controlled. The real application with ER fluid, however, has many limitations to be overcome; temperature fluctuation, moisture, dust, aggregation, precipitation, and low yield stress, for example. The magnitude and the characteristics of yield stress of ER fluid plays an important role in practical applications. In this research, a dynamic simulation on the squeezing flow of the ER fluid was carried out. Numerical simulation on isolated chains was performed to find out the effect of hydrodynamic and electrostatic force depending on the chain location, the squeezing rate, and the chain structure. Suspension model that is composed of a large number of particles was also investigated. The increase of normal stresses as well as the existence of a yield stress at an earlier stage could be observed, and the effective control of the normal stresses could be achieved at an optimal condition of the hydrodynamic force and the electrostatic force.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2002.10b
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• pp.123-124
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• 2002

A press shoe is an element of a machine for squeezing water from wood pulp in the field of manufacturing paper. This is used to compress the pulp enveloped by felt sheet with a large roller. The squeezing force is made by hydraulic pressure. The press shoe has a mechanism similar to a partial hydrostatic bearing. The pressure profile between press shoe and roller affects their squeezing ability, and partial peak pressure can tear the wet pulp. The curvature of the surface of press shoe varies to reduce the peak pressure and increase the mean pressure simultaneously. Therefore, the prediction of pressure distribution considering partially changed curvature of hydrostatic bearing is very important for designing the press shoe. In this study, the difference formulation of Reynolds' equation for partial hydrostatic bearing is by direct numerical method and a computer program to calculate the pressure distribution is developed. We investigate the effect of partially changed curvature of bearing surface on the pressure distribution. Other design parameter for hydrostatic bearing such as depth of pocket and relative velocity are also studied.

• Journal of the Korean Academy of Esthetic Dentistry
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• v.30 no.2
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• pp.91-101
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• 2021

The interdental papilla area is a difficult area for connective tissue graft (CTG) due to its narrow space. So Regeneration of interdental papilla is very challenging work. It is very difficult when the teeth have contact with adjacent teeth, but if there was only 3mm of space between the teeth, CTG was not very difficult. Therefore, through the orthodontic force, a 3mm space between the teeth was intentionally created. The CTG was performed using a microblade, and only one vertical incision was performed off the gingival margin, and the graft was performed by inserting the grafts through here. After a period of maintenance, I was able to gather the teeth again with orthodontic force and regenerate the interdental papilla. I named this technique ELSA Technique (Enlargement of space - Labial graft - Squeezing - for Augmentation of papilla). If interdental papilla is lost due to periodontal disease, ELSA techniques can regenerate interdental papilla very efficiently.

• Journal of Power System Engineering
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• v.14 no.5
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• pp.63-70
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• 2010

Recently the power window system is widely used in automobiles to increase convenience of passengers and drivers. However some accidents or injuries have been caused by malfunction or misusage of the system. Therefore safety regulations of the system to cope up with these accidents have been strengthened gradually in many countries. Especially in America, since 2005, all vehicles which had power window system should be contented with FMVSS 118-S5 regulations. We suggest very low-cost anti-pinch window control system satisfying the regulation in this paper. Hall sensors are used and installed around a motor rotor with ring magnet to detect motor speed for anti-pinch. The optimum number of hall sensor and location angel of them are mainly investigated to get sufficient speed resolution for anti-pinch. Through some experiments, the validity of the suggested system was verified to satisfy the regulation.

• Structural Engineering and Mechanics
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• v.12 no.6
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• pp.595-614
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• 2001

This paper studies the behaviour of a homogeneous cable in a horizontal rigid duct and loaded by an axial compressive force. This behaviour is characterized by spatial buckling modes, named sinusoidal and helical, due to friction and total or partial cable locking. The evaluation of critical buckling loads involved by drilling technology has been studied by many authors. This work presents a new formulation, taking the friction effects into account, for the transmission of the axial load during the postbuckling process. New analytical expressions of pitches in both buckling cases are also given. A life-sized bench is presented, which permits to study the laying of optical fiber cables by squeezing them into an underground duct. Finally, analytical solutions are compared with experimental tests and finite element simulations.

• Journal of Power System Engineering
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• v.16 no.1
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• pp.98-105
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• 2012

안티핀치 시스템은 파워 윈도우 상승 시에 인체의 특정 부위가 창문 틈 사이에 끼여 발생하는 치명적인 사고를 방지하기 위한 안전 시스템이다. 이러한 안티핀치 시스템은 물체의 끼임을 검출하는 센서 방식에 따라 접촉식과 비접촉식 두 가지로 크게 구분된다. 본 논문에서는 접촉식의 한 방법으로 전류 정보에 의해 강화된 미국의 안전 규정 FMVSS 118-S5를 만족하는 안티핀치 시스템을 제안한다. 안티핀치 시스템에 사용된 전류 정보는 추가적인 장치의 부착 없이도 기존의 파워 윈도우용 모터 드라이브에 내장된 과전류 검출용 전류 센서를 이용하여 쉽게 얻을 수 있다. 또한 전류 정보는 물체의 끼임을 신속히 검출, 반영함으로써 안티핀치 시스템에 요구되는 반전력 저감에 기여한다. 특히, 본 논문에서는 전류의 임계값이 모터 경년 변화나 운전 조건에 따라 변동하는 문제점을 개선하기 위해 핀치 상태를 효과적으로 판정할 수 있는 자동 임계값 설정 방법을 제안한다. 마지막으로 다양한 실험 및 시험을 통해 제안된 안티핀치 시스템이 FMVSS 118-S5를 만족함을 보인다.

• Journal of Korea Foundry Society
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• v.24 no.6
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• pp.331-339
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• 2004

Melt-extrusion process, a metallic melt poured and solidified up to semisolid state in the container can be directly extruded through the die exit to form a product of bar shape without other intermediate processes. In this study, the fabrication characteristics of the process were evaluated with various process parameters, such as preheating temperature of extrusion dies, extrusion temperature and extrusion ratio. AI-Cu alloys were successfully extruded after squeezing out of liquid during melt-extrusion with smaller force compared to the solid extrusion. Soundly AI-Cu alloy bar was fabricated at the preheating temperature of $500{\sim}520^{\circ}C$. The range of extrusion temperature for soundly melt-extruded AI-Cu alloy bar was increased with increasing extrusion ratio. Mechanical properties of melt-extruded AI-Cu alloy bars were found change with Cu content of the melt-extruded bars due to the occurrence of segregation. The various extrusion temperature yielded equiaxed structure with a grains size about 200 ${\mu}m$.