• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2008.03a
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• pp.202-212
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• 2008

A three-dimensional computation was conducted to understand effects of the low Reynolds number on the loss characteristics in a transonic axial compressor, Rotor67. As a gas turbine becomes smaller in size and it is operated at high altitude, the operating condition frequently lies at low Reynolds number. It is generally known that wall boundary layers are thickened and a large separation occurs on the blade surface in axial turbomachinery as the Reynolds number decreases. In this study, it was found that the large viscosity did not affect on the bow shock at the leading edge but significantly did on the location and the intensity of the passage shock. The passage shock moved upstream towards leading edge and its intensity decreased at the low Reynolds number. This change had large effects on the performance as well as the internal flows such as the pressure distribution on the blade surface, tip leakage flow and separation. The total pressure rise and the adiabatic efficiency decreased about 3% individually at the same normalized mass flow rate at the low Reynolds number. In order to analyze this performance drop caused by the low Reynolds number, the total pressure loss was scrutinized through major loss categories such as profile loss, tip leakage loss, endwall loss and shock loss.

• Tunnel and Underground Space
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• v.27 no.3
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• pp.132-145
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• 2017

Shock loss was not applied for the tunnel ventilation of road tunnel in the past. However, pressure losses due to the shock loss can be significant in network double-deck road tunnel in which combining and separating road structures exist. For the optimum ventilation design of network double-deck road tunnel, this study conducted 3D CFD numerical analysis for the shock loss at the combining and separating flows. The CFD model was made with the real-scale model that was the standard section of double-deck road tunnel. The shock loss coefficient of various combining and separating angles and road width was obtained and compared to the existing design values. As a result of the comparison, the shock loss coefficient of the $30^{\circ}$ separating flow model was higher and that of the two-lane combining flow model was lower. Since the combining and separating angles and road width can be important for the design of shock loss estimation, it is considered that this study can provide the accurate design factors for the calculation of ventilation system capacity. In addition, this study conducted 3D CFD analysis in order to calculate the shock loss coefficient of both combining and separating flows at flared intersection, and the result was compared with the design values of ASHRAE. The model that was not widened at the intersection showed three times higher at the most, and the other model that was widened at the intersection resulted two times higher shock loss coefficients.

• Asian-Australasian Journal of Animal Sciences
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• v.30 no.1
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• pp.94-99
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• 2017

Objective: The aim of this study was to investigate the expression of heat shock protein (HSP) 90, 70, and 60 in chicken muscles and their possible relationship with quality traits of meat. Methods: The breast muscles from one hundred broiler chickens were analyzed for drip loss and other quality parameters, and the levels of heat shock protein (HSP) 90, 70, and 60 were determined by immunoblots. Results: Based on the data, chicken breast muscles were segregated into low (drip loss${\leq}5%$), intermediate (5%${\geq}9.5$) drip loss groups. The expression of HSP90 and HSP60 were significantly lower in the high drip loss group compared to that in the low and intermediate drip loss group (p<0.05), while HSP70 was equivalent in abundance in all groups (p>0.05). Conclusion: Results of this study suggests that higher levels of HSP90 and HSP60 may be advantageous for maintenance of cell function and reduction of water loss, and they could act as potential indicator for better water holding capacity of meat.

• Tunnel and Underground Space
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• v.27 no.1
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• pp.50-57
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• 2017

In this study, the experiment for determining shock loss at the branch is conducted for the design of network double-deck road tunnel ventilation. The shock loss coefficient that determines the quantity of shock loss has been considered only regarding the constant aspect ratio of circular or rectangular section. However the suggestion of shock loss coefficient is needed since the aspect ratio of double-deck road tunnel for small vehicle is considered around 1:3 with the low height in Korea. The experiment model was made with the scale of around 1:23 applying Reynolds similarity law, so that the shock loss coefficient on the branch of the large aspect ratio was measured. The result of the study showed that shock loss coefficients of both split branch and straight branch were measured two to three times higher than those calculated from the theoretical equation or design values of previous studies. Therefore the study resulted the effect of large aspect ratio on shock loss coefficient was huge, and it is expected that precise design value can be suggested for the design of network double-deck tunnel ventilation.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.21 no.1
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• pp.65-68
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• 1999

Multiple facial trauma patient should be carefully treated because of severe bleeding on extraoral and intraoral wound, possibilty of airway obstruction and hypovolemic shock. Hypovolemic shock may be divided to hemorrhagic shock and non-hemorrhagic shock. Also hemorrhagic shock is divided to mild, moderate and severe shock according to the degree of blood volume depletion. Mild shock occurs in blood loss of less than 20% of blood volume and moderate shock does in blood loss of 20-40% of blood volume. And Severe shock occurs in blood loss of more than 40% of blood volume. The goal of emergency care of trauma patient is that respiration and perfusion should be recovered to satisfactory level and that normal vital sign is maintained. We reported the case of multiple facial trauma patient with severe bleeding and hopovolemic shock and metabolic acidosis who was treated with adequate supply of fluid transfusion, intubation, tracheostomy and emergency operation.

• Journal of Periodontal and Implant Science
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• v.33 no.4
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• pp.555-562
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• 2003

The present study has been performed to evaluate Porphyromonas gingivalis (P.gingivalis) heat shock protein(HSP)60 as a candidate vaccine to inhibit multiple bacteria-induced alveolar bone loss. Rats were immunized with P.gingivalis HSP60 and experimental alveolar bone loss was induced by infection with multiple periodonto -pathogenic bacteria. Post-immune rat anti-P.gingivalis HSP IgG levels were significantly elevated and have demonstrated highly significant inverse relationship with the amount of alveolar bone loss induced by multiple bacteria. Results from PCR detection of subgingival bacterial plaque indicated that the vaccine successfully eradicated the multiple pathogenic species. We concluded that P.gingivalis HSP60 could potentially be developed as a vaccine to inhibit periodontal disease induced by multiple pathogenic bacteria.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.26 no.3
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• pp.235-241
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• 2016

Underwater weapon system is required to structurally strong material, since as it is directly exposed to external shock. It should also be using the lightweight material in order to take advantage of buoyancy. Composite materials meet these requirements simultaneously. Particularly in the case of submarine, composite materials are widely used. It is important to have a high strength enough to be able to withstand external shock, but it is also important to attenuate it. In a method for the shock damping, viscoelastic damping materials are inserted between the high strength composite material as a sandwich structure. Shock attenuation can be evaluated in the loss factor. In ASTM(American Society of Testing Materials), evaluation method of the loss factor of cantilever specimens is specified. In this paper, mode tests of the cantilever are performed by the ASTM standard, in order to calculate the loss factor of the viscoelastic damping material by the specified expression. Further, for verifying of the calculated loss factor, mode test of compound beams is carried out. In addition, the characteristics of the material were analyzed the effect on the loss factor.

• Korean Journal of Occupational Health Nursing
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• v.26 no.1
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• pp.19-29
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• 2017

Purpose: The purpose of this study was to define and clarify the concept of reality shock in new graduated nurses. Methods: The hybrid model was used to develop the concept of reality shock. The model included a field study. The participants were 9 newly graduated nurses with a nursing career spanning less than a year. Results: The reality shock in newly graduated nurses was identified to have three dimensions and seven attributes. Specifically: 1) the dimension of performance included two attributes (conflict between theory and practice, and being overwhelmed by the workload), 2) the dimension of relationship included three attributes (loss of support, embarrassment from interference, and relational withdrawal), 3) the dimension of expectations included two attributes(value confusions and incongruity in personal life). Conclusion: Newly graduated nurses' reality shock was defined as a state of incongruence in their entire life that the new nurses experienced owing to value confusions that occurred due to the conflicts between theory and practice in an unfamiliar work environment, getting overwhelmed by the workload, and withdrawing establishing relationships with others due to the loss of support and excessive interference. These findings could help develop intervention strategies to decrease reality shock in newly graduated nurses.

• Journal of The Korean Astronomical Society
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• v.54 no.3
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• pp.103-112
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• 2021

The intracluster medium (ICM) is expected to experience on average about three passages of weak shocks with low sonic Mach numbers, M ≲ 3, during the formation of galaxy clusters. Both protons and electrons could be accelerated to become high energy cosmic rays (CRs) at such ICM shocks via diffusive shock acceleration (DSA). We examine the effects of DSA by multiple shocks on the spectrum of accelerated CRs by including in situ injection/acceleration at each shock, followed by repeated re-acceleration at successive shocks in the test-particle regime. For simplicity, the accelerated particles are assumed to undergo adiabatic decompression without energy loss and escape from the system, before they encounter subsequent shocks. We show that in general the CR spectrum is flattened by multiple shock passages, compared to a single episode of DSA, and that the acceleration efficiency increases with successive shock passages. However, the decompression due to the expansion of shocks into the cluster outskirts may reduce the amplification and flattening of the CR spectrum by multiple shock passages. The final CR spectrum behind the last shock is determined by the accumulated effects of repeated re-acceleration by all previous shocks, but it is relatively insensitive to the ordering of the shock Mach numbers. Thus multiple passages of shocks may cause the slope of the CR spectrum to deviate from the canonical DSA power-law slope of the current shock.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.04a
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• pp.200-203
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• 2011

Supersonic ejectors are simple mechanical components, which generally perform mixing and recompression of two fluid streams. Ejectors have found many applications in engineering. In aerospace engineering, they are used for high altitude testing (HAT) of a propulsion system by reducing the pressure of a test chamber. It is composed of three major sections: a vacuum test chamber, a propulsive nozzle, and a supersonic exhaust diffuser (SED). This paper aims at the improvement in HAT facility by focusing attention on the vertical firing rocket test stand with shock generators. Shock generators are mounted inside the SED for improving the pressure recovery. The results clearly showed that the performance of the ejector-diffuser system was improved with the addition of shock generators. The improvement comes in the form of reduction of the starting pressure ratio and the vertical height of test stand. It is also shown that shock generators are useful in reducing the total pressure loss in the SED.