• Journal of the Korea Institute of Military Science and Technology
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• v.7 no.4 s.19
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• pp.125-132
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• 2004

The radial slot configuration in the solid propellant grain is usually fabricated by the polyurethane foam slot former The foam cannot be easily removed from the solid propellant, some can remain in the slot. Analogue solid propellant rocket motors using polyurethane foam to shape the slot are static fired with the foam former still in place in the slot. The pressure increases at the slot part are measured and there are indications of the propellant cracks at the insulations above the slot. The pressure increase is produced at the beginning of the burning sequence as the foam will hinder the combustion gas of the burning propellant from flowing into the central bore. The pressure increase up to about 300psi is predicted for the motor tested and this pressure increase depends on the gap between the propellant and foam surfaces and remaining foam volume. This amount of pressure increase inside of the slot is estimated to cause the propellant crack. To prevent this pressure increase, minimizing the foam remainder in the slot and making sufficient chamfering at the comer of the slot entrance are suggested.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2010.11a
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• pp.686-691
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• 2010

Flash boiling takes place when the thermodynamic state of the liquid deviates from its saturation limit over which the liquid temperature exceeds by a certain degree of superheat. The liquid jet introduced into the lower pressure zone than the liquid saturation pressure experiences a sequence of the atomization and disintegrated into numerous faster and smaller droplets. In the present study spray characteristics for a flash swirl spray were experimentally investigated. Injectant temperature is raised by a high frequency dielectric heating method and local spray characteristics are instantly measured by Global Sizing Velocimetry (GSV, TSI Inc.). Dependence of dimensionless superheat degree and injection pressure on total and local SMDs and mean droplet size is quantitatively examined. The flash swirl spray has the relation in the injection pressure and nozzle diameter in order to determine the spray quality, including the dimensionless superheat degree. Small droplets occur in the void core and local droplet size distributions largely depend on the dimensionless superheat degree and the injection pressure.

• Journal of the Society of Disaster Information
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• v.19 no.3
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• pp.582-596
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• 2023

Purpose: This study aims to explore the ways to improve the security of temporary shelters in case of nuclear power plant accidents. Method: In this study, we mainly rely on the case studies on previous nuclear power plant accidents-Chernobyl, Fukushima, and Three Mile Island (TMI) cases. Result: The current radiation emergency response plans for nuclear power plant accidents center around the evacuation procedure. As a result, the concept of "shelter in place" has been understood as a means of assisting resident evacuation. However, based on the case studies, we find that encouraging shelter in place, rather than simply emphasizing evacuation, would help minimize unnecessary casualties, especially in case of the accidents rated greater than or equal to INES 5. To facilitate better shelter in place, we recommend utilize apartments as temporary shelters and suggest some possible improvements to ensure those apartments could be equipped with technologies for high radiation protection. Conclusion: To ensure better shelter in place, we recommend using apartments as temporary shelters, and we seek to supplement the function of apartments by using shielding, positive pressure, and sealing technologies.

• Journal of Korean Academy of Fundamentals of Nursing
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• v.5 no.2
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• pp.280-292
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• 1998

Pressure sores are a serious concerns in that respect to increasing risk of medical complications and medical costs. Prevention and care of pressure sores is an essential area of nursing practice. The nurse at ICU should be more careful of maintaining the skin integrity of patients especially than at any other place. This study was conducted to determine if the risk facotrs of pressure sores and nutritional status of the patients at risk for pressure sores is related the occurance of pressure sore. The risk group refers the patients having the below 14 scores of the braden scale. The 100 subjects were recruited from the ICU ward at an university hospital in Choongnam. The parameters for nutritional status are the blood chemistry including plasma protein, albumin, hemoglobin and the anthropometric measurements consisting of weight, BMI, LBM, the proportion of body fat, body fluid and triceps skin fold using bioimpedence analizer and caliper. The results are as follows : 1. The subjects were 55 years and stayed 8 days on average. Of the 100 subjects, males were 61%, neurologic/neurosurgical diseases were 68% and the incidence of pressure sores was 17% mainly occuring within 3days after the admission. 2. The present paralysis(or paraplegia) and edema(arm, leg, trunk) were showed more significantly the subjects with pressure sores than those without pressure sores. 3. Regarding with the nutritional status, the subjects with pressure sores had significantly lower the weight, BMI, LBM, body fluid, albumin than the ones without pressure sores. This results were supported the reports of previous studies that the decreased weight and albumin could be the important predictors of pressure sores. Thereafter we should encourage these factors to be utilized in predicting pressure sores for a comprehensive assessment. Nurse should identify patients at risk of the development of pressure sores, assess their nutritional status and dietary intake at regular intervals.

• Proceedings of the KSR Conference
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• 2011.10a
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• pp.2393-2399
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• 2011

In the case where the bottom of railroad is penetrated by non-excavation construction method, the design is performed based on the assumption that there is no displacement and no change of stress However, measurement data showed that reduction of earth pressure and relaxation of stress take place by the displacement. In this study, we investigated the earth pressure on the structure under the railroad constructed by a non-excavation method and the stress relaxation region. The design based on earth pressure is non-economical because it is an over design. Relaxation of stress may lead to road base settlement and rail irregularly due to the reduced railroad supporting stiffness, to ballast crack in the case of concrete roadbed. The result showed that it is reasonable to set the stress on the structures as active earth pressure not as earth pressure at rest. Additionally, the study on the stress relaxation region identified the regions that should be supported in future construction by a non-excavation method.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.20 no.1
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• pp.17-25
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• 2008

To achieve the unidirectional airflow in a cleanroom, we need to predict accurately the static pressure losses at the lower plenum and to control properly the opening pressure ratio of access floor panels based on these pressure losses. At first, the present study proposed a correlation to predict the velocity distribution at the lower plenum, because the accuracy to predict pressure losses at the lower plenum depends on how to calculate the velocity correctly against the inner structures at the lower plenum. In the second place, this study proposed correlations which considered the effect of inner structures such as columns, ducts and equipments at the lower plenum on pressure losses. In order to test the accuracy of these correlations, we compared air flow patterns before regulating the opening ratio of access floor with those after regulating. Results after regulating the opening ratio of access floor show good unidirectional uniform airflow pattern. So the present method can be used as an important tool to control the air flow in a cleanroom.

• Journal of Biosystems Engineering
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• v.26 no.3
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• pp.245-252
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• 2001

This study was carried out to investigate the effect of three factors(dynamic load, inflation pressure and multiple passes of the tire) on the contact pressure and the soil stresses under the tire. A series of soil bin experiment was conducted with a 6.00R14 radial-ply tire for sandy loam soil. Tire contact pressure at soil surface and soil stresses at 10cm and 20cm soil depth were measured for the three levels of dynamic load(1.17kN, 2.35kN and 3.53kN), for the three levels of tire inflation pressure(103.42kPa, 206.84kPa and 413.69kPa), and for five different number of passes(1, 2, 3, 4 and 5 pass). The following results were drawn from this study 1) As dynamic load, inflation pressure and number of passes of the tire increased, tire contact pressure at soil surface and soil stresses at 10cm and 20cm soil depth increased accordingly. Thus increased in dynamic load, inflation pressure and number of passes of the tire would increase soil compaction. 2) The effect of three different factors, or dynamic load, inflation pressure and number of passes of the tire, decreased as the soil depth increase. Consequently, it was found that the soil compaction at a shallow depth in soil is larger than that at deep place in soil. 3) The increase of dynamic load and number of passes increased soil stress exponentially, but the increase of inflation pressure increased soil stress linearly. The effect of tire inflation pressure on soil stress was relatively less than that of the dynamic load. Therefore, it was concluded that dynamic load is more important factor affecting soil compaction in comparison to the inflation pressure of tire.

• Journal of The Korean Society of Integrative Medicine
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• v.7 no.1
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• pp.75-80
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• 2019

Purpose : This study investigated the effect of bamboo stepping exercises on the blood pressure of the elderly. This study was performed for 8 weeks. Methods : The study participants included 25 people aged 65 and over. Of the participants, 16 were in the hypertensive elderly group and 9 were in the normal blood pressure elderly group. The participants stepped on semicircular bamboo for 20 minutes 3 times a week for 8 weeks. The participants' blood pressure was measured 3 times before and after 8 weeks of exercise. The mean values of the 3 before and after measurements were compared and analyzed statistically. Results : The systolic blood pressure of the hypertensive elderly group decreased significantly from $134.6{\pm}21.1mmHg$ to $119.9{\pm}18.1mmHg$ (p<.05). The diastolic blood pressure of the hypertensive elderly group decreased from $70.2{\pm}10.5mmHg$ to $66.1{\pm}9.8mmHg$, but the difference was not significant. The systolic blood pressure of the normal blood pressure elderly group decreased significantly from $127.2{\pm}18.7mmHg$ to $115.5{\pm}19mmHg$ (p<.05). The diastolic blood pressure of the normal blood pressure elderly group decreased from $72.6{\pm}11.3mmHg$ to $68.2{\pm}12mmHg$, but the decrease was not significant. Conclusion : After completing 8 weeks of the bamboo stepping exercises, the elderly participants' systolic blood pressure was effectively reduced. Today, lifestyle modifications, such as daily exercise, are necessary to control the blood pressure of the elderly. We hope that the bamboo stepping exercises, which are easy to perform and are not restricted by place and time, will become part of the elderly health policy.

• Journal of ILASS-Korea
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• v.10 no.1
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• pp.1-9
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• 2005

When the water jets heated up to the saturation temperature at a high line pressure are sprayed into a reduced (atmospheric) pressure through an air-assisted nozzle, the jets experience sudden exposure into a reduced pressure, get superheated and produce steam bubbles while atomization processes of jets are taking place. This process is called flash atomization. In this study the flash atomization of superheated water jets assisted by air has been studied. Sprays with flash atomization have been photographed at various water and air flow rates and water superheats. It has been found that the spray angle with flash atomization increases with water superheat and water flow rate but decreases with air flow rate. The degree of change of spray angle has been analyzed and correlated as a function of superheat, air and water flow rates.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.1803-1807
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• 2005

The pipe which it uses from the nuclear power plant or factory by a long period use and a corrosive action the inside defect occurs on the inside. abstract here. The ESPI method is in order to investigate the laser light in the measurement object it will be able to measure the wide territory whole in once, does not receive an effect in direction of defect not to be, has the strong point it will be able to measure a change of place arrowhead real-time defect. It measured a inside defect of pressure vessel by using Out of plane ESPI and In plane of ESPI. It compared a each method result.