• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.05a
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• pp.1053-1060
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• 2006

This paper consider an initially deformed state caused by the pressurized fluid flowing through the pipe at a constant velocity. When the initial forte is neglected in curved pipes, the natural frequencies are reduced as flow velocity increases. However, when the initial tension took into account, the natural frequencies are not changed with the change of the flow velocity. As the internal pipe pressure is increased the natural frequencies are also slightly increased. In free vibrational simulation of piping systems in petrochemical plants, it is necessary to calculate the initial state force due to the velocity and the pressure of the fluid flow from the equilibrium first, then the force should be included in the equation of motion of the systems to get more accurate natural frequencies. In this study, calculate the mass matrix and stiffness matrix of piping system by MATLAB

• Journal of Biomedical Engineering Research
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• v.17 no.1
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• pp.43-48
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• 1996

We investigated the energistics of the physiological heart model by comparing predictive indexes of the myocardial oxygen consumption (MOC), such as tension-time index (R), tension-time or force-time inteual (FTI), rate-pressure product (RPP), pressure-work index, and systolic pressure-volume area (PVA) when using the electro-hydraulic left ventricular device (LVAD). We developed the model of LVAD incorporated the closed-loop cardiovascular system with a baroreceptor which can control heart rate and time-varying elastance of left and right ventricles. On considering the benefit of the LVAD, the effects of various operation modes, especially timing of assistance, were evaluated using this coupled computer model. Overall results of the computer simulation shows that our LVAD can unload the ischemic (less contractile) heart by decreasing the MU and increasing coronary flow. Because the pump ejection at the end diastolic phase of the natural heart may increase the afterload of the left ventricle, the control scheme of our LVAD must prohibit ejecting at this time. Since the increment of coronary flow is proportional to the peak aortic pressure after ventricle contraction, the LVAD must eject immediately following the closure of the aortic valve to increase oxygen availability.

• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.16 no.1
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• pp.92-99
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• 2020

High-temperature mechanical behaviors of Type 316L stainless steel (SS), which is considered as one of the major structural materials of Generation-IV nuclear reactors, were investigated through the tension and creep tests at elevated temperatures. The tension tests were performed under the strain rate of 6.67×10^-4 (1/s) from room temperature to 650℃, and the creep tests were conducted under different applied stresses at 550℃, 600℃, 650℃, and 700℃. The tensile behavior was investigated, and the modeling equations for tensile strengths and elongation were proposed as a function of temperature. The creep behavior was analyzed in terms of various creep equations: Norton's power law, modified Monkman-Grant relation, damage tolerance factor(λ), and Z-parameter, and the creep constants were proposed. In addition, the tested tensile and creep strengths were compared with those of RCC-MRx. Results showed that creep exponent value decreased from n=13.55 to n=7.58 with increasing temperature, λ = 6.3, and Z-parameter obeyed well a power-law form of Z=5.79E52(σ/E)^9.12. RCC-MRx showed lower creep strength and marginally different in creep strain rate, compared to the tested results. Same creep deformation was operative for dislocation movement regardless of the temperatures.

• The korean journal of orthodontics
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• v.9 no.1
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• pp.99-103
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• 1979

For the purpose of investigating the response of the periodontal tissue in relation to the experimental tooth movement, the rats were inhibited from collagen formation by adminstration of aminoacetonitrile. Findings were as follows: 1) In experimental group, the principal fibers of the periodontal ligament came to run parallel along the alveolar bone or root surface on the pressure side, while the decrease in density, irregular arrangement, and partial loss of principal fibers were observed on the tension side. 2) Sharpey's fibers at the alveolar bone decreased in number, and as the aminoacetonitrile administration continued, the capability of matrix formation decreased on the tension side, the narrowing of the alveolar septum and poor-bony trabeculation appeared on the pressure side. 3) In cementum, Sharpey's fibers were distributed irregularly. The formation of acellura cementum was decreased on the tension side, while the formative capability of cellular cementum was increased. 4) The degree of staining by Herovici technique decreased in the periodontal membrane. By PAS and ninhydrine -Schiff reaction it was appeared weakly positive in the region where the Sharpey's fibers existed.

• Journal of Chest Surgery
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• v.25 no.12
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• pp.1399-1403
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• 1992

The evaluation of the effectivess of ongoing cardiopulmonary resucitation efforts is dependent on the commonly used methods, such as the presence of femoral or carotid artery pulsations, arterial blood gas determinations, peripheral arterial pressure and intracardiac pressure monitoring. But recent studies suggest that end-tidal carbon dioxide tension serves as a non-invasive measurement of pulmonary blood flow and therefore cardiac output under constant ventilation. A prospective clinical study was done to determine whether end-tidal carbon dioxide monitoring in open heart surgery under cardiopulmonary bypass could be used as a prognostic indicator of bypass weaning. We monitored end-tidal PCO2 values continuously during cardiopulmonary bypass in 30 patients. "Ohmeda 5210 CO-2 monitor" under infrared absorption method were incorperated into the ventilator circuit by means of a side point adaptor between endotracheal tube and ventilator tubing. 18 patients[Group I ] were res-ucitated from partial bypass followed by aorta cross clamp off and 12 patients[Group II ] from aorta cross clamp off followed by partial bypass. But there was no difference between two groups[p>0.05]. The value of end-tidal carbon dioxide tension during ventricular fibrillation or nearly arrest state was 6.6$\pm$2.9 mmHg, and at the time of spontaneous beating was 19.3$\pm$5.6 mmHg[Mean$\pm$Standard deviation], In conclusion end-tidal carbon dioxide tension monitoring provides clinically useful, continous, noninvasive and supplementary prognostic indicator during cardiopulmonary bypass weaning procedures.rocedures.

• International Journal of Aeronautical and Space Sciences
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• v.9 no.1
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• pp.137-146
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• 2008

Proper amount of entrained air and nip force should be also considered to minimize ballooning phenomenon since tight contact between a roller and web is required. In this paper, various web materials, PET(Polyester) and OPP(Oriented Poly Propylene) have been selected and investigated to satisfy high-speed printing requirement. Several web speeds, web tensions, and temperature conditions are imposed on each web materials and the pressure and gap profiles as well as nip force have been calculated. Increase of both the winding roller radius and the incoming wrap angle is considered under proper taper tension at 500 m/min of rewinding roller. By solving coupled Reynolds equation and web deflection equation simultaneously, the fluid-structure interaction process has been developed and is applied to the rewinding roller to investigate the ballooning phenomenon which causes guiding problems in high-speed printing performance conditions. By adjusting the linear taper tension, stress distribution between rewinding webs can be remarkably reduced and stable pressure and gap profile with ignorable ballooning phenomenon have been found.

• Nuclear Engineering and Technology
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• v.53 no.9
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• pp.3112-3121
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• 2021

One of the major factors affecting the life span of a Reactor Pressure Vessel (RPV) is the Pressurised Thermal Shock (PTS). PTS is a thermo-mechanical load on the RPV wall due to steep temperature gradients and structural load created by internal pressure of the fluid within the RPV. Safe operating life of a nuclear power plant is ensured by carrying out fracture analysis of the RPV against thermal shock. Carrying out fracture tests on RPV/large scale components is not always feasible. Hence, studies on laboratory level specimens are necessary to validate and supplement the prototype results. This paper aims to study the fracture behaviour of standard Compact Tension [C(T)] specimens, made of RPV steel 20MnMoNi55, subjected to thermal shock through experimental and numerical investigations. Fracture tests have been carried out on the C(T) specimens subjected to thermal transient load and tensile load to quantify the effect of thermal shock. Crack resistance curves are obtained from the fracture tests as per ASTM E1820 and compared with those obtained numerically using XFEM and a good agreement was found. A quantitative study on the crack tip plastic zone, computed using cohesive segment approach, from the numerical analyses justified the experimental crack initiation toughness.

• The Journal of Korean Academy of Orthopedic Manual Physical Therapy
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• v.27 no.3
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• pp.69-78
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• 2021

Background: Approximately 30% of people suffer from chronic neck and shoulder pain. Chronic neck and shoulder pain arise due to the exposure to continuous low loading and monotonous work. This is a common musculoskeletal disorder in a society. As physical therapists, we should give appropriate treatment to these people. Methods: A total of 26 patients with chronic neck and shoulder myalgia were randomly allocated into two experimental groups. First, 13 patients received shoulder strength training, while the other 13 patients received cervical mobilization. Outcome measures included bilateral pressure pain threshold by using an algometer at upper trapezius, visual analogue scale (VAS) to express their pain scale, and muscle tension by using myoton pro device pre-intervention and after the final treatment. Results: The VAS and muscle tension in upper trapezius significantly decreased (p<.05) in both groups; however, no differences between two groups were observed (p>.05). The pressure pain threshold in upper trapezius significantly increased (p<.05) in both groups; yet, again, the differences between the groups did not reach statistical significance (p>.05). Conclusion: As methods of treatment, shoulder-specific strength training and cervical mobilization can be appropriate approaches to the treatment of neck and shoulder musculoskeletal disorder.

• The Korean Journal of Physiology
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• v.2 no.1
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• pp.39-45
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• 1968

Recently, in this department, pressure-displacement curve and breaking tension of dog and human tympanic membrane were studied using intact, fresh or dried tympanic membrane attached to external auditory meatus. However, physical property, proper elasticity-Young Modulus, of the tympanic membrane has not been clarified yet. Present study is attempted to further clarify proper Young Modulus of tympanic membrane, and to distinguish possible difference between layer of stratum radiatum and layer of stratum circulare of tympanic membrane in breaking tension and in Young Modulus. Tympanic membrane was excised from sacrificed dog, and preparation was made into the size of approximately 1 mm in width and 3 mm in length. In fresh or dried tympanic membrane, which was dried at $80^{\circ}C$ for 24 hrs., some preparations were made along the long axis parallel to the fibers of radial direction, and others were made along the long axis perpendicular to the radial fibers-circular direction. Breaking tension and displacement according to loading, were measured and Young Modulus was calculated in tympanic membrane preparations under the different experimental conditions. Results obtained are summarized as follows : 1. Young Modulus of fresh tympanic membrane in radial direction was $6.57{\times}10^8\;dyne/cm^2$, and that of fresh preparation in circular direction was $1.68{\times}10^8\;dyne/cm^2$. The Young Modulus of fresh tympanic membrane in radial direction resembles to that of silk and whale moustache. In dried tympanic membrane, Young Modulus of preparation of radial direction was $30.2{\times}10^8\;dyne/cm^2$ and that of preparation in circular direction was $25.0{\times}10^8\;dyne/cm^2$. 2. Breaking tension of fresh tympanic membrane was 44.9 gm/mm in radial preparation, and 7.9 gm/mm in circular preparation. In dried tympanic membrane, breaking tension was 46.7 gm/mm in preparation of radial direction, and 17.2 gm/mm in preparation of circular direction. 3. Much smaller breaking tension of the circular preparation-one fifth to the radial preparation-seemed to be responsible for the higher incidence of circular fiber breaking in tympanic membrane performation caused by trauma or sudden change in atmospheric pressure. 4. The correlation seemed to be very close between breaking tension and Young Modulus in tympanic membrane.

• Proceedings of the Korean Geotechical Society Conference
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• 2005.03a
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• pp.788-795
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• 2005

In this study, the progressive failure and creep of the traditional ground anchor structure were decreased and a new ground anchor that can attain the required pull-out resistance even in soft sandy soils with low confining pressure was developed. Ground anchors are classified depending on the kind of stress the grout is subjected. If the grout material is subjected to tension then it is classified as tension anchor while when the grout material is subjected to compression it is classified as compression anchor. The ground anchor that possesses both the tension and compression mechanism mentioned above is known as composition anchor. It is the objective of this study to develope this type of composition anchor. The structure of the newly developed ground anchor was presented. Pull-out test in different types of soil and the behaviour during Pull-out test was also presented.