• Transactions of the Korean Society of Mechanical Engineers A
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• v.36 no.7
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• pp.823-828
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• 2012

The soft recoil mechanism was an effective mechanism for reducing the recoil force by forwarding momentum. There were some parameters such as the fire angle, firing position, and initial pressure of the recuperator, which influenced the forwarding momentum. These parameters affected the generation of the forwarding momentum in the soft recoil mechanism. To design for the mechanism, the parameters affecting momentum were studied to consider some reasonable conditions. Among the various parameters, the initial pressure of the recuperator and firing position was confirmed as a key factor to have affected the momentum. It was determined that the recoil force had a minimum value when the initial pressure of the recuperator was 180.

• Journal of Biomedical Engineering Research
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• v.37 no.1
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• pp.39-45
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• 2016

A pressure measurement system was developed to verify magnitude and position of transferred pressure on the body surface during the intermittent pneumatic compression (IPC) which is one of the most well-known methods for the prevention of deep vein thrombosis (DVT). Eighty force sensing resistors (FSR) were arranged on a mannequin leg and a hardware controller sensed, digitized, and transferred pressure data every second while IPC was being applied. Finally, sensed pressure data were color coded and visualized on the 3D model with lab-developed software. The pressure data were also saved to files for further analysis. Using this measurement system, the changing pattern of pressure was measured on the mannequin leg by changing both chamber pressure and cuff tightness. As a result, net pressure transferred onto the body surface is dependent on chamber pressure and cuff tightness. Under the same chamber pressure, the tighter a cuff was worn, the wider compressed area was and the shorter compression cycle was. Also transferred pressure was proportional to both chamber pressure and cuff tightness.

• Progress in Medical Physics
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• v.32 no.4
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• pp.153-158
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• 2021

Purpose: This study evaluated the features of a pressure mapping system for patient motion monitoring in radiation therapy. Methods: The pressure mapping system includes an MS 9802 force sensing resistor (FSR) sensor with 2,304 force sensing nodes using 48 columns and 48 rows, controller, and control PC (personal computer). Radiation beam attenuation caused by pressure mapping sensor and signal perturbation by 6 and 10 mega voltage (MV) photon beam was evaluated. The maximum relative pressure value (mRPV), average relative pressure value (aRPV), the center of pressure (COP), and area of pressure distribution were obtained with/without radiation using the upper body of an anthropomorphic phantom for 30 minutes with 15 MV. Results: It was confirmed that the differences in attenuation induced by the FSR sensor for 6 and 10 MV photon beams were small. The differences in mRPV, aRPV, area of pressure distribution with/without radiation are about 0.6%, 1.2%, and 0.5%, respectively. The COP values with/without radiation were also similar. Conclusions: The characteristics of a pressure mapping system during radiation treatment were evaluated on the basis of attenuation and signal perturbation using radiation. The pressure distribution measured using the FSR sensor with little attenuation and signal perturbation by the MV photon beam would be helpful for patient motion monitoring.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.30 no.4A
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• pp.337-342
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• 2010

Generally most sluice gates are closed and opened by a mechanical winch, a winch using an oil-pressure, or a winch mixing both. Because of their size and structure, they should be safely operated with more than two pulling devices helping each other. At the moment of their opening and closing, there usually occur some additional loads to the structure which cannot be exactly measurable at the stage of designing. Such additional loads can cause the sluice gate to be unbalanced and make it hard to open and close the gate, and by also overloading a winch, they can inflict a significant damage to the safety of the sluice gate. This paper explains a FDC(Force-Displacement Control) system which simultaneously considered the oil-pressure and displacement in order to evenly distribute the force and make a winch balanced at the opening and closing motion. This FDC system was implemented by means of the PID(Proportional Integral Derivative) function of XG 5000 program. It was experimented on a model of the sluice gate winch with the hydraulic oil pressure cylinder. The experiments showed that the developed FDC system made the winch of hydraulic oil pressure cylinder open and close cooperatively in spite of various external loads. Therefore the FDC system is proven effective when it is applied to a winch of sluice gate.

• The Journal of Korean Academy of Prosthodontics
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• v.44 no.1
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• pp.103-111
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• 2006

Statement of problem: The previous unilateral bite force recorder has several limitations for taking long time for measuring and causing discomfort to subjects. Because of these reasons, it could not use widely for epidemiological researches. However, 'Dental Prescale System' which is new equipment for measuring bite force, is more convenient for measuring bite force than previous unilateral recorder. Purpose: The purpose of this study was to compare a new technique(Dental Prescale System) using pressure sensitive foils for recording of maximal jaw closing force with conventional measurement using unilateral bite force recorder Material and method: This studies included 22 healthy dental students in college of dentistry Yonsei university in Rep of Korea. Mean age was 23.9 years. All subjects had continuous dental arches and no significant malocclusion or signs from the teeth and craniomandibular system. The Dental Prescale System (Fuji Film, Tokyo, Japan) consists of a horseshoe-shaped pressure sensitive sheet (50H, R type) and a computerized scanning system.(FPD705) We also used unilateral bite force recorder(Denbotics Co. Seoul, Rep.Korea) for comparing with Dental Prescale. Results and conclusion: The total bite force recorded with Dental Prescale System (1423 N) was systematically higher than that recorded by unilateral bite force recorder. (256 N) However, the maximum bite force values measured in the two ways were significantly correlated (r=0.46, p<0.05). The Dental Prescale bite force calculated for first molar (208 N) was lower than that recorded by unilateral bite force recorder. (256 N) The two values were also very significantly correlated. (r=0.66. p<0.001) There were significantly different in bite force between two measurement methods. The reasons were first, unilateral bite force recorder measured only the bite force of a part of teeth, and Dental Prescale measured the total teeth force. Second, in measurement, a difference in muscle contraction appeared by an extent of mouth-opening. Third, unilateral bite force recorder has the reducing effect of the bite force by protective tape. Fourth, Dental Prescale has limitations during the computer scanning procedure. Therefore, Dental Prescale System is considered to be a very promising alternative to be conventional bite force recording methods.

• Proceedings of the Korea Concrete Institute Conference
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• 2000.10a
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• pp.267-272
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• 2000

The modeling on uplift pressure on the foundation of a dam on which it was constructed, and on the interface between the dam and foundation is a critical aspect in the analysis of concrete gravity dams. The evaluation of stress intensity factor at the crack tip of concrete gravity dam due to uplift pressure effect by surface integral method is performed in this study. The effects of body force, overtopping pressure and water pressure on the crack-face are also considered in this study.

• Proceedings of the KSME Conference
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• 2008.11a
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• pp.1221-1225
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• 2008

In this paper, analysis of pressure and flow characteristics have been performed with a servo valve. A number of servo valve have been used in various applications including the inserting device, bearing transportation and welding machine. By analysis of flow and pressure gradient, technology can be obtained about optimal simulation of high response servo valve for competitiveness. Spool displacement and ratio of inlet/outlet pressure can give big effects to flow and pressure inside servo valve.

• Journal of the Ergonomics Society of Korea
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• v.8 no.2
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• pp.43-47
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• 1989

An instrumentation system to measure the pressure between elastic bodies and between an elastic and a rigid body has been developed. The force between elastic bodies can be measured only by Elastric- body pressure Meter. As a standard Elastic-body pressure Meter, Model RCG-24A consists of 24 pick-ups, one switch box and one amplifier and measuring is possible at each of 24 measuring spots by swithing one to the nest using the switch box. The system can be used in various specialized disciplines, such as ergonomics, anthropometry and biomechanics.

• Journal of Korean Tunnelling and Underground Space Association
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• v.15 no.3
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• pp.301-310
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• 2013

Jet fans are installed in road tunnels in order to maintain critical velocity when fire occurs. Generally the number of jet fans against fire are calculated by considering critical velocity and flow resistance by wall friction, vehicle drag force, thermal buoyance force and natural wind. In domestic case, thermal buoyance force is not considered in estimating the number of jet fans. So, in this study, we investigated the pressure loss due to the thermal buoyance force induced by tunnel air temperature rise and the impact of thermal buoyance force on the number of jet fans by the numerical fire simulation for the tunnel length(500, 750, 1000, 1500, 2000, 3500m) and grade (-1.0, -1.5, -2.0%). Considering the thermal buoyance force, number of jet fans have to be increased. Especially in the case of 100MW of heat release rate, the pressure loss due to thermal buoyance force exceed the maximum pressure loss due to vehicle drag resistance, so it is analyzed that number of 2~11 jet fans are needed additionally than current design criteria. Thus, in case of estimating the number of jet fans, it must be considered of thermal buoyance force induced tunnel air temperature rise by fire.

• The korean journal of orthodontics
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• v.18 no.2
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• pp.311-327
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• 1988

Vascular changes in the periodontal ligament of the rat incisors following application of experimental orthodontic forces were examined by the India ink perfusion method. 57 rats were used for this experiment. The rats were divided into experimental group (54 rats) and control group (3 rats). 54 experimental rats were divided into group I (27 rats) and group II (27 rats). The right and left upper incisors of group. I and group II rats were separated distally with forces of 20gm, 70gm respectively. The vascular changes of periodontal ligament were observed histologically by means of light microscope after 1, 2 and 3 days of tooth movement and 1,3,5,8,14, and 21 days after removal of orthodontic force. The results were as follows; 1. After one day of tooth movement, occlusion of blood vessels, hyalinization of periodontal ligament and resorption of alveolar bone adjacent to the alveolar crest on pressure side were observed. Above the tissue changes on the pressure side of group II were more severe than those of group I. Especially, septal bone of group II was separated after 2 days of tooth movement. 2. In tension zones, periodontal space was widened and periodontal fibers were orientated in the direction of puil. The blood vessels of periodontal ligament were distended. New bone deposition was seen along the inner surface of the alveolus after 2 days of tooth movement. 3. After 3 days of tooth movement, deposition of new bone was seen along the periosteal surface of alveolar bone on pressure side, progressing with increasing after removal of orthodontic force. Remodelling of the new bone was occurred 5 days after removal of orthodontic force. 4. 3 days after removal of orthodontic force, invasion of blood vessels into the marginal periodontal ligament on pressure side was observed clearly and the vessels below the epithelial attachment were increased. 5. After removal of orthodontic force, hyalinized structures disappeared concomittantly with an invasion of blood vessels from the neighboring periodontal ligament. 14 days after removal of orthodontic force, the vessels in the periodontal ligament of group I were finished the vascular rearrangement. 21 days after removal of orthodontic force, the vessels in the periodontal ligament of group II were finished the vascular rearrangement.