• Carbon letters
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• v.13 no.4
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• pp.205-211
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• 2012

Methanol as a carbon source in chemical vapor deposition (CVD) graphene has an advantage over methane and hydrogen in that we can avoid optimizing an etching reagent condition. Since methanol itself can easily decompose into hydrocarbon and water (an etching reagent) at high temperatures [1], the pressure and the temperature of methanol are the only parameters we have to handle. In this study, synthetic conditions for highly crystalline and large area graphene have been optimized by adjusting pressure and temperature; the effect of each parameter was analyzed systematically by Raman, scanning electron microscope, transmission electron microscope, atomic force microscope, four-point-probe measurement, and UV-Vis. Defect density of graphene, represented by D/G ratio in Raman, decreased with increasing temperature and decreasing pressure; it negatively affected electrical conductivity. From our process and various analyses, methanol CVD growth for graphene has been found to be a safe, cheap, easy, and simple method to produce high quality, large area, and continuous graphene films.

• Proceedings of the KIEE Conference
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• 2006.07b
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• pp.677-678
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• 2006

Pressure risc is an important design factor and affects significantly on the characteristics of gas circuit breakers. For self-blast circuit breakers, the nozzle ablation plays important role in pressure-building up and should be properly considered for the accurate calculation. In this paper, the nozzle ablation is treated as a boundary condition and the pressure is calculated from mass fractions of PTFE and SF6. The amount of the ablated mass of a nozzle is assumed to be proportional to the are energy and the area of nozzle surface that directly touches arc. The calculation result is compared with measured data and shows good agreement with it.

• Journal of the Korean Society of Industry Convergence
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• v.21 no.6
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• pp.429-437
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• 2018

The process gas piping of the offshore plant can cause a massive explosion if the gas leakage occurs during operation. For the purpose of precaution of gas leakage accident, an air pressure test is performed on the process equipment tests using a test pump as much as the power to the piping inner side, mix 99% nitrogen gas and 1% helium gas. The purpose of the air pressure test is to check the work conformity process by handling and regulation for initial piping process, assembly, installation of module, welding, center alignment of the pipes assembling flange gasket in an unrestrained free state. In this paper, the regulation of the problematic air pressure test was analyzed and the solution criteria were established. And leakage tests of existing equipment were performed applying these solution methods. As a result, it was confirmed that there was no problem.

• Journal of the Microelectronics and Packaging Society
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• v.24 no.1
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• pp.51-56
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• 2017

In this paper, we have developed a differential pressure flow sensor designed as a single capacitive type. And the sensor was fabricated using a MEMS process. Differential pressure flow sensors are the most commonly used sensors for industrial applications. The sensing diaphragm and bonding joint of the MEMS pressure sensor are easily broken at high pressure. In this paper, we proposed a structure in which the diaphragm of the sensor was not broken at a pressure exceeding the proof pressure, and the differential pressure sensor was designed and manufactured accordingly. The operating characteristics of the sensor were evaluated at a pressure three times higher than the sensor operating pressure (0-3 bar). The developed sensor was $3.0{\times}3.0mm$ and measured with a LCR meter (HP 4284a) at a pressure between 0 and 3 bar. It showed 3.67 pF at 0 bar and 5.13 pF at 3 bar. The sensor operating pressure (0-3 bar) developed a pressure sensor with hysteresis of 0.37%.

• The Journal of Internal Korean Medicine
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• v.33 no.4
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• pp.543-557
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• 2012

Objectives : The purpose of this study which adopted a qualitative method was to evaluate blood pressure management behaviors of pre- and stage 1 hypertension patients and to provide fundamental data for developing a strategy about proper oriental medical treatment through analyzing factors related to a moxibustion clinical trial. Methods : Semi-structured interviews that focused on personal experiences with hypertension and its management were conducted with 10 hypertensive patients. The interviews lasted for approximately 50 minutes. Results : Most participants recognized that the direct cause of high blood pressure was unhealthy behavior rather than inheritance. Thus, the hypertensive patient believed they could recover their blood pressure to a normal level through removing the direct cause of hypertension instead of taking drugs. The reasons for these statements were that the drugs for controlling hypertension are not natural and they may have side effects. On future management plan of patients, most of them will continue to keep moxibustion and healthy behavior in the well-controlled blood pressure group. However in the uncontrolled blood pressure group, there was an increasing tendency to begin medication. Conclusions : For developing a strategy for an individual approach to hypertension management, we need to develop a client-centered attitude and strategy. That is, we need to tailor our approach to individual cases to avoid generalizations and stereotyping when developing an adherence increasing strategy.

• Journal of Korean Academy of Rural Health Nursing
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• v.6 no.1
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• pp.33-43
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• 2011

Purpose: This study was done to verify the effects of a self-regulation program for management of hypertension. Method: Thirty patients with hypertension registered in a community health center were selected as the experiment group, and control group were patients in another community health center, matched for age and gender. The self-regulation program included daily blood pressure checks, periodic counseling, and health education. A self-check digital device with instructions was provided for self-monitoring of blood pressure, and the participants were interviewed before they took part in the program. Results: The first hypothesis was supported: There will be a greater reduction in both systolic and diastolic blood pressure for patients with hypertension who participate in the self-regulation program compared to patients in the control group. The second hypothesis was also supported: Patients with hypertension who participate in the self-regulation program will perform self-care activities better than those in the control group. Conclusion: The findings indicate that a self-regulation program reduces systolic and diastolic blood pressure and improves self-care in patients with hypertension. It is recommended that this self-regulation program be used in community health clinics for management of hypertension and prevention of complications.

• International Journal of Naval Architecture and Ocean Engineering
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• v.6 no.1
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• pp.27-38
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• 2014

Flow mixing and pressure drop characteristics for marine selective catalytic reduction applications were investigated numerically to develop an efficient static mixer. Two different mixers, line- and swirl-type, were considered. The effect of vane angles on the relative intensity, uniformity index, and pressure drop was investigated in a swirl-type mixer; these parameters are dramatically affected by the mixer geometry. The presence of a mixer, regardless of the mixer type, led to an improvement of approximately 20% in the mixing performance behind the mixer in comparison to not having a mixer. In particular, there was a tradeoff relationship between the uniformity and the pressure drop. Considering the mixing performance and the pressure drop, the swirl-type mixer was more suitable than the line-type mixer in this study.

• Current Photovoltaic Research
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• v.4 no.3
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• pp.87-92
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• 2016

The effects of selenization pressure on the structural, optical and electrical properties of the CIGS thin films prepared by RF magnetron sputtering using a single quaternary target were investigated. At selenization pressures lower than atmospheric pressure, CIGS thin films formed non-stoichiometric compounds due to deficiencies of Se vapor. In contrast, when selenization process was conducted at above atmospheric pressure, the residence time of Se vapor inside the tube increased so that the Se element could be incorporated within vacant sites of the CIGS structure, resulting in the formation of stoichiometric CIGS thin films. High quality CIGS thin films could be obtained when the selenization process was performed at pressures greater than atmospheric and $550^{\circ}C$.

• Food Science and Biotechnology
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• v.18 no.4
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• pp.861-866
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• 2009

Effects of pressure come-up and holding times on the inactivation of Salmonella enterica and Listeria monocytogenes were evaluated in deionized water, milk, orange juice, and tomato juice with pH 6.76, 6.85, 3.46, and 4.11, respectively. The inoculated samples were subjected to high pressure treatments at 300, 400, and 500 MPa for less than 10 min at $30^{\circ}C$. At 500 MPa, the numbers of S. enterica and L. monocytogenes in deionized water, orange juice, and tomato juice were reduced by more than 6 log CFU/mL during the come-up time. Compared to orange and tomato juices, milk showed a considerable baroprotective effect against S. enterica and L. monocytogenes. At 300 MPa, the D values for S. enterica in milk, orange juice, and tomato juice were 0.94, 0.41, and 0.45 min, while those for L. monocytogenes were 9.56, 1.11, and 0.94 min, respectively. Low pH resulted in a noticeable synergistic effect on the inactivation of S. enterica and L. monocytogenes in orange and tomato juices. Therefore, these results might provide more useful information for designing the entire high hydrostatic pressure (HHP) conditions, taking the come-up time reduction, and food system.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.9 no.3
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• pp.130-136
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• 2004

In September 2003 wind-measuring drifters were air-deployed in front of the projected path of Hurricane Fabian from an altitude between 300 m and 400 m. Eight drifters transmitted wind, air pressure and SST data through ARGOS and three drifters were within 35 km of the hurricane center. Measurements of the air pressure in the eye of the hurricane by dropsondes, suggested the air pressure at the eye was between 939 hPa and 944 hPa. The lowest pressure measured by a Minimet was 943 hPa at 33 km from the hurricane center. Fabian cooled the SST at its center from $28.9^{\circ}C$ to $26.8^{\circ}C$. After the passage of Fabian, SST warmed to between $27.5^{\circ}C$ and $28.5^{\circ}C$ in 7 days.