• Korean Journal of Hydrosciences
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• v.7
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• pp.77-86
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• 1996

An air chamber is design to keep the pressure from exceeding a predetermined value, or to prevent low pressures and colum separation. Therefore, it can be used to protect against rapid transients in a pipe system following abrupt pump stoppage. In this research, an air chmber was applied to a hypthetical pipe system to analyze attenuation effect of pressure head for different air volumes, locations, chamber areas, coefficients of orifice loss and pollytropic exponents. With an increase of air volume, the maximum pressure head at pump site is decreased and the minimum pressure head is imcreased. For different locations and areas of the chamber, the attenuation effects do not show much difference. Also, as the orifice loss coefficient increases, the maximum pressure head is decreased. For different polytropic exponents, isothermal process shows lower maximum pressure head than that of the adiabatic process.

• Journal of the korean Society of Automotive Engineers
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• v.13 no.3
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• pp.32-42
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• 1991

In SI engine research the pressure data in cylinder is the most important fundamental ones leading to engine efficiencies and performances. It is, therefore, necessary to obtain accurate pressure data and yet it is often impossible to install a reliable data producing, flush-mounted type pressure transducer in a cylinder of small and medium size multicylinder SI engines. When flush mounting the transducer is not possible, the spark-plug type pressure transducer is commonly used as an alternative. In this case, the transmission tube of spark-plug type pressure transducer introduces distortions in the pressure signal. Efforts were made to understand the dynamic characteristics of spark-plug pressure transducer by shock tube tests and real engine experiments. In engine experiment the cylinder pressure data were simultaneously obtained by both flush mounted and spark-plug type pressure transducers of certain transmission tube geometry. Those pressure data collected by spark-plug type pressure transducer were tested for correction to flush mounted ones by the application of transfer function. As a result of the calibration the IMEP difference between F/M data and improved S/P data was shown to be corrected about 75-98% from the original ones.

• Journal of the Korean Mathematical Society
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• v.36 no.2
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• pp.299-316
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• 1999

We consider two finite difference approxiamations to a singular boundary value problem arising in the study of a nonlinear circular membrane under normal pressure. It is shown that the rates of convergence are O(h) and O($h^2$), respectively. An iterative scheme is introduced which converges to the solution of the finite difference equations. Finally the numerical experiments are given

• Journal of Advanced Marine Engineering and Technology
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• v.18 no.3
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• pp.94-101
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• 1994

To develope the new simulator for the analysis of fluid flow information, the influence of various convective difference schemes were evaluated. General curvilinear coordinate system with nonorthogonal grids was adopted for the successful analysis of various complex geometries. Computation results show that if we can not obtain full grid numbers within available computational environment, we need to use higher order finite difference schemes to keep the prediction accuracy.

• The Journal of Korean Society for School & Community Health Education
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• v.18 no.1
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• pp.57-68
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• 2017

Objectives: The purpose of the study was to evaluate the effect of community intervention on reducing salt intake among college students on their knowledge, attitude and practice of low-salt diet. Methods: A community intervention planned to increase college students' knowledge, attitude and practice of low-salt diet. The intervention comprised of 1 lecture on salt and health, 4 campaigns on low-salt diet, and 2 taste testing was carried out from March 24 to May 19, 2015. All the intervention was open to entire university while data was collected from a panel of convenient sample. We used the baseline data of 251 students, 226 students completed post-test. Post-test data on knowledge, attitude, and practice, blood pressure measurement, and urine salt test were collected on May 25 and 26 by trained nursing students and graduates. Baseline data were collected on March 17 and 18. Data were analyzed using IBM-SPSS 21.0 for t-test and ANCOVA. Results: Regarding a general characteristic and health behavior, there was statistically significant difference in living arrangement(p<0.001), amount of monthly allowance(p=0.005) and frequency of eating-out(p<0.001) between the two regions in this study. However, there was no statistically significant difference in gender, major, smoking, drinking and frequency of breakfast. Regarding a characteristic related to low-salt diet, there was statistically significant difference in diastolic blood pressure level(p=0.002), urine test(p=0.001). But there was no statistically significant difference in knowledge, attitude, practice of low-salt diet and systolic blood pressure. There was no statistically significant difference in their knowledge of low-salt diet(F=1.588, p=0.209), attitude(F=2.182, p=0.141), practice(F=3.507, p=0.062) and systolic blood pressure(F=1.723, p=0.191), diastolic blood pressure(F=1.552, p=0.214), urine test after a community intervention. Conclusions: Community intervention that does not have concrete target group doesn't seem to be effective on increasing knowledge, attitude and practice of the entire community, not even in university-a somewhat closed community. It is suggested to apply a target specific intervention in order to have efficient and effective outcome from a intervention.

• Fire Science and Engineering
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• v.30 no.2
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• pp.56-61
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• 2016

Recently, Since buildings are bigger and higher, the damage of human life can be increased by fire flame and smoke in fire. Smoke control system is necessary to decrease this damage. Therefore, Air supply pressurization smoke control system is applied to vestibule of escape stairway. NFSC requires pressure differential of above 40 Pa, but pressure differential is excessively overpressure in the field. It is known that the cause of this over pressure differential is much leakage of damper. Over pressure differential can bad effect to escaper by pressurizing the door. Analyze the real leakage of damper by increasing the number of dampers operation for identifying this problems. The result of testing, the leakage has difference between new dampers and increased the number of operation dampers. As the static preassure increase, the leakage difference increase. Comparison with preceding study, this result has similar linear tendency.

• The Korean Journal of Pharmacology
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• v.8 no.2
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• pp.21-26
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• 1972

Zea mays Linne, which belongs to Graminae family, has been ordinarily used as edibles and fodder. Its stigma, Maydis Stigma, has been discarded without any special application with the exception of being used as diuretic in the sphere of Chinese medicine. Moreover, the pharmacological research toward Maydis Stigma as a medicinal herb has not been regretfully undertaken at all. The authors hereby paid attention to this point of view and made experiment to find out whether the water extract of Maydis Stigma might possess some pharmacological effect on the blood pressure of the rats or not. $LD_{50}$ to the mice was determined and the experiment was performed making the use of several agents related to the blood pressure such as atropine, Avil, dichloroisoproterenol and hexamethonium. The blood pressure of the rats and rabbits was recorded with the equipment of polygraph (Grass model 7 DAB) and its accessory, Statham pressure transducer. The results of the experiment are as follows. 1. $LD_{50}$ to the mice weighing 20g is determined 1,125 mg/kg. 2. The blood pressure manifests the gradual decrease by the rate of $-15.50{\pm}3.32,\;-22.14{\pm}8.73$ and $-46.25{\pm}5.17\;mmHg$ in proportion to ZW 25, 50 and 150mg/kg administered to the rats. 3. The blood pressure also manifests the same gradual decrease in proportion to ZW administered to the rabbits. 4. It is of significant difference to manifest the increase of $+5.14{\pm}4.65\;mmHg$ in the rats pretreated with atropine as compared with $-22.14{\pm}8.73\;mmHg$ of control group when administered each ZW 50mg/kg. 5. The administration of ZW 50 mg/kg to the rats pretreated with Avil, dichloroisoproterenol and hexamethonium does not manifest the significant difference in comparison with the control group.

• Journal of Digital Convergence
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• v.15 no.5
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• pp.471-478
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• 2017

The purpose of this study was to investigate the changes of blood pressure and total cholesterol after eating Hizikia fusiforme for 8 weeks with 100g of rice per day. As a result, the systolic blood pressure of the group ingesting Hizikia fusiforme significantly decreased. Second, diastolic blood pressure decreased significantly in both groups, but there was no difference between groups. Third, the systolic - diastolic blood pressure difference showed a significant decrease in the group of ingestion of Hizikia fusiforme, while that of the group without intake of Hizikia fusiforme increased. Fourth, total cholesterol decreased significantly in the group consuming Hizikia fusiforme but increased in the group not consuming Hizikia fusiforme. The above results indicate that total intake of 100 g of dried Hizikia fusiforme per day was effective in decreasing total cholesterol and reducing systolic blood pressure.

• Journal of Ocean Engineering and Technology
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• v.30 no.6
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• pp.505-519
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• 2016

If the seabed is exposed to high waves for a long period, the pore water pressure may be excessive, making the seabed subject to liquefaction. As the water pressure change due to wave action is transmitted to the pore water pressure of the seabed, a phase difference will occur because of the fluid resistance from water permeability. Thus, the effective stress of the seabed will be decreased. If a composite breakwater or other structure with large wave reflection is installed over the seabed, a partial standing wave field is formed, and thus larger wave loading is directly transmitted to the seabed, which considerably influences its stability. To analyze the 3-D dynamic response characteristics of the seabed around a composite breakwater, this study performed a numerical simulation by applying LES-WASS-3D to directly analyze the wave-structure-soil interaction. First, the waveform around the composite breakwater and the pore water pressure in the seabed and rubble mound were compared and verified using the results of existing experiments. In addition, the characteristics of the wave field were analyzed around the composite breakwater, where there was an opening under different incident wave conditions. To analyze the effect of the changed wave field on the 3-D dynamic response of the seabed, the correlation between the wave height distribution and pore water pressure distribution of the seabed was investigated. Finally, the numerical results for the perpendicular phase difference of the pore water pressure were aggregated to understand the characteristics of the 3-D dynamic response of the seabed around the composite breakwater in relation to the water-structure-soil interaction.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1998.04a
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• pp.277-285
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• 1998

This paper presents the deformation characteristics of the moving pressure plate in a balanced type vane pump that widely used automotive power steering systems. Moving pressure plate can control the clearance between rotor and plate in accordance with load pressure variation; it always guarantees that pump to have optimal volumetric efficiency. In this paper, firstly, we calculate the acting force on the pressure plate, which is used to determine the angular position and load condition for analyzing the deformation of pressure plate. Secondary, finite element method is used for the deformation analysis. As results of acting force analysis, it is found that maximum difference of forces occurs at angular position 28$\circ$ from the small arc center of cam ring and load pressure is a dominant factor to affect acting force variation. The deformation of pressure plate increases as load pressure increases. At high load pressure, the deformation of pressure plate becomes larger than the initial clearance between rotor and plate. Therefore, it is required to design the plate for controlling the deformation.