• Journal of Environmental Science International
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• v.27 no.6
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• pp.349-358
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• 2018

In this study, using coke dust from ironwork, the pulse pressure on a pulse air jet bag filter was investigated considering the influence of the pressure loss due to filtration velocity and pressure intervals. The research on the optimal pulse pressure prediction of a pulse air jet type bag filter using coke dust showed the following results. Pressure loss volatility produced by the pulse pressure under low dust concentration(0.5, $1g/m^3$) and low face velocity(1.25 m/min) was less than $10mmH_2O$. This suggests that the pulse pressure has a low impact on the pressure loss. In contrast, pressure loss volatility under high dust concentration($3g/m^3$) and high face velocity(1.75 m/min) was $25mmH_2O$. Therefore, pulse pressure with high dust concentration and high face velocity has a strong influence on the pressure loss volatility, compared to the condition of low dust concentration and low face velocity. The optimal pulse pressure of inlet dust concentration($0.5g/m^3$) was $6kg/cm^2$ under the same face velocity(1.75 m/min). As concentration increased from 1 to $2g/m^3$, the pulse pressure gradually reached $5kg/cm^2$ thus indicating that the pulse pressure($5kg/cm^2$) is pertinent at a high concentration($3g/m^3$). The pulse intervals: 20, 25 and 30 sec, which are relatively longer than 10 and 15 sec, corresponded to high pressure loss volatility produced by the pulse pressure. Furthermore, low pressure loss volatility was noted at $5kg/cm^2$ of the overall pulse pressure.

• Journal of Korean Society for Atmospheric Environment
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• v.19 no.1
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• pp.25-31
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• 2003

Ceramic filter has been demonstrated as an attractive system to improve the thermal efficiency and to reduce the effluent pollutants. Removal of particulates from the hot gas stream is very important in air pollution control. In particular, the elimination of the particulate matters discharged from a gas turbine at high temperature can prevent the corrosion inside the IGCC. In this study, a Lab. scale test and numerical simulation were carried out to comprehend the relationship between pulse jet pressure and recovery of pressure drop and to characterize the reverse cleaning flow through a ceramic fil-ter element under high temperature and high pressure. When the pulse-jet pressures were 2, 3 and 4 kg/$ extrm{cm}^2$, the cleaning effect increase of about 10~30% by recovery of pressure drop caused by pulse pressure. Cleaning effect at 45$0^{\circ}C$ was greater than that at 55$0^{\circ}C$ or 650$^{\circ}$ for the same pulse pressure. According to the result of the present simulation, high pressure has been formed in terminal and central regions in our models and temperature distribution caused by pulse air is to be uniform comparatively on inner surface of filter.

• Journal of Environmental Science International
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• v.23 no.12
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• pp.2045-2056
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• 2014

In this study, pressure drop was measured in the pulse jet bag filter without venturi on which 16 numbers of filter bags (Ø$140{\times}850{\ell}$) are installed according to operation condition(filtration velocity, inlet dust concentration, pulse pressure, and pulse interval) using coke dust from steel mill. The obtained 180 pressure drop test data were used to predict pressure drop with multiple regression model so that pressure drop data can be used for effective operation condition and as basic data for economical design. The prediction results showed that when filtration velocity was increased by 1%, pressure drop was increased by 2.2% which indicated that filtration velocity among operation condition was attributed on the pressure drop the most. Pressure was dropped by 1.53% when pulse pressure was increased by 1% which also confirmed that pulse pressure was the major factor affecting on the pressure drop next to filtration velocity. Meanwhile, pressure drops were found increased by 0.3% and 0.37%, respectively when inlet dust concentration and pulse interval were increased by 1% implying that the effects of inlet dust concentration and pulse interval were less as compared with those changes of filtration velocity and pulse pressure. Therefore, the larger effect on the pressure drop the pulse jet bag filter was found in the order of filtration velocity($V_f$), pulse pressure($P_p$), inlet dust concentration($C_i$), pulse interval($P_i$). Also, the prediction result of filtration velocity, inlet dust concentration, pulse pressure, and pulse interval which showed the largest effect on the pressure drop indicated that stable operation can be executed with filtration velocity less than 1.5 m/min and inlet dust concentration less than $4g/m^3$. However, it was regarded that pulse pressure and pulse interval need to be adjusted when inlet dust concentration is higher than $4g/m^3$. When filtration velocity and pulse pressure were examined, operation was possible regardless of changes in pulse pressure if filtration velocity was at 1.5 m/min. If filtration velocity was increased to 2 m/min. operation would be possible only when pulse pressure was set at higher than $5.8kgf/cm^2$. Also, the prediction result of pressure drop with filtration velocity and pulse interval showed that operation with pulse interval less than 50 sec. should be carried out under filtration velocity at 1.5 m/min. While, pulse interval should be set at lower than 11 sec. if filtration velocity was set at 2 m/min. Under the conditions of filtration velocity lower than 1 m/min and high pulse pressure higher than $7kgf/cm^2$, though pressure drop would be less, in this case, economic feasibility would be low due to increased in installation and operation cost since scale of dust collection equipment becomes larger and life of filtration bag becomes shortened due to high pulse pressure.

• Journal of the Korean Society of Propulsion Engineers
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• v.26 no.1
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• pp.98-106
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• 2022

To develop reliable dual pulse rocket motor, vacuum ignition performance at high altitude and design stability for rupture pressure of the Pulse Separation Device(PSD) are required. In this study, rupture pressure analysis method for the membrane type PSD of the dual pulse rocket motor was developed. The PSD rupture pressure formulation was derived from strain-pressure relationships. The PSD vacuum rupture test apparatus and the PSD 1 second vacuum ignition test apparatus were developed, which can simulate the high altitude vacuum environment. Rupture pressure of PSD was analyzed by conducting the PSD vacuum rupture test, and design values of PSD were derived. Finally, vacuum ignition performance and rupture pressure of the designed PSD were validated with PSD 1 second vacuum ignition test.

• The Journal of the Society of Korean Medicine Diagnostics
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• v.18 no.3
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• pp.137-148
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• 2014

Objectives This study was conducted to derive consensus about physical attributes in pressure pulse waveform and pulse conditions by Delphi study. Methods Delphi research was conducted for 2 rounds via e-mail. 8 Professors who lecture on a diagnostics of K. M. from the society of Korean medicine diagnostics were participated in this survey. They were asked for answering about series of definition for a physical attribute in pressure pulse waveform and combination for physical attributes of pulse conditions. Results 4 survey items were decided to have high validity and 9 survey items were decided to come to consensus about a physical attribute in pressure pulse waveform. 6 pulse condition were decided to come to consensus. Conclusion Using Delphi method, physical attributes in pressure pulse waveform and combinations of physical attribute in pulse condition come to consensus.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.18 no.2
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• pp.149-160
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• 2008

Bag-filter system has been widely used in industrial field to remove the particulate matters from the exhaust gas. The cylindrical type of bag-filter has been generally used. But it has many shortcomings. The reattachment of separated particles on the surface of bags could result in high pressure drop of bag-filter system and subsequent decrease of air flow rate since the cylindrical type bag-filter system should have the upward flow pattern. In addition, the supply of very high pressure pulse air jet to remove particulate matters on the surface of filter could result in a frequent rupture of bags. To overcome these shortcomings of the cylindrical type, the rectangular type was developed in the developed countries and imported to Korea. But, there was not many design data available to understand the mechanisms. Thus, the fundamental experiments were conducted in this study to get some ideas about the pulse jet cleaning of rectangular type bag filter system. The experimental factors are as follows; pulse distance, pulse duration, pulse interval, pulse pressure and pulse nozzle type. Experiments followed the factorial design method. With the shorter pulse distance, the distribution of pressure drops was relatively not uniform while the particulate removal efficiency was higher. With the longer duration of pulsing and the more number of pulse nozzle, the removal efficiency was higher and the pressure drop distribution was more uniform.

• Korean Journal of Oriental Medicine
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• v.12 no.2 s.17
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• pp.93-101
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• 2006

Pulse feeling is one of the most important diagnosis method in Oriental medicine. But it is not easy to make an objective and standardized diagnosis. In this study, we found how to quantify diagnosis. Specially dally the high practicality in clinic, we search some parameters especially well-related to floating and sinking pulse by statistic analysis. By extension, we find the pulse patterns of the floating and sinking pulse. We choose 15 subjects diagnosed as floating pulse and 15 subjects diagnosed as sinking pulse by oriental doctors. And their pulse signals were acquired by Pulse analyzer which has piezoresistive pressure sensor. For the quantification of the floating and sinking pulse, at first, we examined the parameters which were highly correlated with oriental doctor's diagnosis. And then we derived pulse patterns of the floating-sinking pulse from preprocessed signal and its ensemble average. We also looked trend variation (PH-Curve) between contact and pulse pressure. As a result, statistically there is the biggest difference between contact pressure, the maximum pulse pressure, diastolic area (Ad) and floating and sinking data. Through the PH-Curve, which represented the relationship between contact and pulse pressure, we could divide the floating and sinking pulse clearly. As a basic research of pulse diagnosis algorithm, we can contribute to select essential parameters in diagnosis algorithm And using these diagnosis method, we expect to find typical pulse patterns and some useful parameters about other pulses like slow/rapid, large/fine pulse and so on. We hope that this study will contribute pulse objectification.

• Journal of Digital Convergence
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• v.20 no.4
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• pp.411-418
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• 2022

The purpose of this study is to investigate the relationship between sleep time and pulse pressure in Korean adults, and the research method used data from the 7th period (2016-2018) of the National Health and Nutrition Examination Survey. Subjects were 5,707 persons aged 20 years or older, and for frequency and percentage continuous data, mean and standard deviation, cross analysis and independent t-test, and stepwise logistic regression analysis for high pulse pressure were performed. SPSS WIN 18.0 version statistical program was used. was used. As a result of the study, the prevalence of hypertension was higher in the overall population (OR=1.344, 95% CI=1.002-1.803) and in women (OR=1.624, 95% CI=1.112-2.371) when sleeping for more than 9 hours compared to less than 6 hours. high, but not significant in males (OR=1.012, 95% CI=0.631-1.550). Therefore, considering the effects of inappropriate sleep time on health, public health education and management are necessary. Further research on the relationship between sleep time and pulse pressure will be needed.

• Journal of Environmental Science International
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• v.16 no.4
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• pp.449-458
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• 2007

Research results for the pressure drop variance depending on operation conditions such as change of inlet concentration, pulse interval, and face velocity, etc., in a pulse air jet-type bag filter show that while at $3kg/cm^2$ whose pulse pressure is low, it is good to make an pulse interval longer in order to form the first layer, it may not be applicable to industry because of a rapid increase in pressure. In addition, the change of inlet concentration contributes more to the increase of pressure drop than the pulse interval does. In order to reduce operation costs by minimizing filter drag of a filter bag at pulse pressure $5kg/cm^2$, the dust concentration should be minimized, and when the inlet dust loading is a lower concentration, the pulse interval in the operation should be less than 70 sec, but when inlet dust loading is a higher concentration, the pulse interval should be below 30 sec. In particular, in the case that inlet dust loading is a higher concentration, a high-pressure distribution is observed regardless of pulse pressure. This is because dust is accumulated continuously in the filter bag and makes it thicker as filtration time increases, and thus the pulse interval should be set to below 30 sec. If the equipment is operated at 1m/min of face velocity, while pressure drop is low, the bag filter becomes larger and thus, its economics are very low due to a large initial investment. Therefore, a face velocity of around 1.5 m/min is considered to be the optimal operation condition. At 1.5 m/min considered to be the most economical face velocity, if the pulse interval increases, since the amount of variation in filter drag is large, depending on the amount of inlet dust loading, the operation may be possible at a lower concentration when the pulse interval is 70 sec. However, for a higher concentration, either face velocity or pulse interval should be reduced.

• Transactions of Materials Processing
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• v.26 no.5
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• pp.314-322
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• 2017

In the high-speed forming analysis, dynamic material properties considering a high strain rate are required. The split Hopkinson pressure bar (SHPB) experiment was performed for measuring dynamic material properties under high strain rate. The pulse shaping method was used to improve the accuracy of the SHPB experiment. A pulse shaper attached to the front of the incident bar was used for specimen dynamic stress equilibrium through stress wave control. Numerical analysis and SHPB test were performed to verify whether the pulse shaper affects the dynamic stress equilibrium in copper and Al6061 specimens. The results of SHPB test and numerical analysis show that the pulse shaper contributes to the dynamic stress equilibrium. Based on the improved stress equilibrium using a pulse shaper, the flow stress curves for copper and Al6061 materials were obtained at strain rates of 1344.4/sec and 1291.6/sec, respectively.