• 한국연소학회:학술대회논문집
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• 2002.11a
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• pp.141-148
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• 2002

Experimental investigation of the interaction between dual spray formed by swirl type injector was conducted. Experimental parameter was fuel temperature, varied in the range from $-20^{\circ}C$ to $120^{\circ}C$. Measuring parameter were vertical distance from injector tip to patternator and gap between injectors. Volumetric distiribution and SMD were measured for the various combination of parameters. The results of present study show that the arithmetic sum of each of spray is not equal to dual spray, but it is equal above specific fuel temperature. As the increases of fuel temperature, SMD decreases and becomes more uniform. As the increases of gap between injectors, fuel volume and SMD at collision area increases, but penetrated fuel decreases.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 1999.10a
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• pp.2-2
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• 1999

본 연구에서는 액체 로켓용 추진제 분사기로 많이 활용되는 충돌형 분사기중에서 2중 충돌(F-O-O-F)형 분사기에 대한 미립화 특성을 파악하였다. 액적의 크기를 측정하기 위하여 위상/도플러 입자분석기를 사용하였으며, 모의 추진제로 물을 사용하였다. 모의 추진제의 운동량비와 압력 강하량 변화에 따른 2중 충돌(F-O-O-F)형 분사기의 미립화 특성과 크기분포에 대하여 고찰하였다. 분사기 면으로부터 100mm 떨어진 단면에서 산화제/연료의 운동량비가 MR=1.19에서 MR=6.48까지 증가함에 따라 액적크기(SMD)는 감소하였으며, 액적크기(SMD)가 운동량비(MR)에 대하여 SMD= 193.480+15.687MR-5.036M$R^2$+0.415MR$^3$와 같은 관계식에 근사되었다 또한, 연료와 산화제의 압력강하량이 증가할수록 액적크기(SMD)가 감소하였다. 충돌 분무유동장의 액적크기 분포는 Rosin-Rammler 분포함수와 Upper-limit분포함수 모두에 대하여 잘 일치하고 있다. 본 연구의 결과는 액체 로켓용 충돌형 분사기의 초기 설계단계에서 유용하게 사용될 수 있을 것이다.

• Journal of the Microelectronics and Packaging Society
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• v.9 no.1
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• pp.15-20
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• 2002

In this project, we hale developed various techniques for subminiaturization, surface implementation, high frequency design, small-size SMD, performance test and application of the Dual PLL module, which is a core component for the personal communication systems. We also obtained base techniques for the next-generation Dual PLL module design and fabrication techniques for an internationally competitive subminiature Dual PLL module.

• New & Renewable Energy
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• v.5 no.4
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• pp.34-37
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• 2009

Using six SMD(surface mount device) type AlGaAs/GaAs single junction solar cells connected in series, a power source was fabricated for a white GaN LED. The electrical properties of the power source was measured and analyzed under one sun (100mW/$cm^2$) and various indoor light (300 - 900 lux) conditions. Under 600 lux indoor light condition, output power was 17.06 ${\mu}W$ and it was 30.75 ${\mu}W$ under 900 lux indoor light condition. Using the fabricated solar cell power supply, we have turned on the white GaN LED. It was worked well under 15 ${\mu}W$(at 480 lux) power supplied from solar cell array. This kind of solar cell power supply can be used as a power source for ubiquitous sensor network (USN).

• Journal of ILASS-Korea
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• v.24 no.3
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• pp.145-151
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• 2019

Viscoelastic fluid is used in various industrial sites because its cost reduction and environmental benefits by preventing formation of fine droplets that scattered around. However, viscoelastic fluids, unlike newtonian fluids, contain a shear thinning characteristic that decrease in viscosity as shear rate increases and elastic characteristic, making it difficult to predict spray breakup process. In this study we made three test fluids. Boger fluid with viscoelastic characteristics, and two newtonian fluids, were prepared to exclude shear thinning characteristics and study the effects of elastic characteristic only. Flow visualization, spray angle, and SMD were measured for three test fluids using laboratory scale impinging jet test apparatus. As a result, it was confirmed that Boger fluid, unlike the newtonian fluid, was not formed fine droplets that scattered around and the breakup process appeared differently. In addition, SMD was found to be large in Boger fluid, and the SMD according to pressure was confirmed that there is no significant difference.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1996.04a
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• pp.568-573
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• 1996

In this paper, A design strategy of the Surface Mounting Device for accurate and better performance is studied. Analytical Modeling. Sensitivity analysis and optimization are being conducted. The ANSYS software and experimental method are used for verification of the analytical equations withboundary conditons. Through the sensitivity analysis, the most dominant design parameters can be detected. The optimum design parameters for performing given performing given perfomances are selected by using the optimization algorithm. The design tool based on the design strategy for the analysis, modeling and optimization will be useful for a re-design and better perofrmance of the SMD.

• Journal of the Korean Society for Precision Engineering
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• v.14 no.2
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• pp.120-128
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• 1997

In this paper, A design strategy of the Surface Mounting Device for accurate and better performance is studied. Analytical modeling, sensitivity analysis, and optimization are being conducted. The ANSYS software and experimental method are used for the verification of the analytical equations with boundary conditions. Through the sensitivity analysis, the most dominant design parameter can be detected. The optimum design parameters for improving the given performances are selected by using the optimiza- tion algorithm. The design tool based on the design strategy for the analysis, modeling, and optimization will be useful for are-design and better improving of the SMD.

• Proceedings of the Korean Magnestics Society Conference
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• 1996.05a
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• pp.76-77
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• 1996

• Journal of Korean Academy of Nursing
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• v.53 no.1
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• pp.69-86
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• 2023

Purpose: This study aimed to evaluate the effects of digital health interventions on the psychotic symptoms among people with severe mental illness in the community. Methods: A systematic review and meta-analysis were conducted in accordance with the Cochrane Intervention Research Systematic Review Manual and PRISMA. A literature search was conducted of published randomized controlled trials (RCTs) for digital health interventions from January 2022 to April 2022. RevMan software 5.3 was used for quality assessment and meta-analysis. Results: A total 14 studies out of 9,864 studies were included in the review, and 13 were included in meta-analysis. The overall effect size of digital health interventions on psychotic symptoms was - 0.21 (95% CI = - 0.32 to - 0.10). Sub-analysis showed that the reduction of the psychotic symptoms was effective in the schizophrenia spectrum group (SMD = - 0.22; 95% CI = - 0.36 to - 0.09), web (SMD = - 0.41; 95% CI = - 0.82 to 0.01), virtual reality (SMD = - 0.33; 95% CI = - 0.56 to - 0.10), mobile (SMD = - 0.15; 95% CI = - 0.28 to - 0.03), intervention period of less than 3 months (SMD = - 0.23; 95% CI = - 0.35 to - 0.11), and non-treatment group (SMD = - 0.23; 95% CI = - 0.36 to - 0.11). Conclusion: These findings suggest that digital health interventions alleviate psychotic symptoms in patients with severe mental illnesses. However, well-designed digital health studies should be conducted in the future.

• The Journal of Engineering Geology
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• v.34 no.2
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• pp.217-228
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• 2024

During deep drilling, confined aquifers can present various challenges such as the inability to remove cuttings, rapid groundwater influx, and mud loss. Particularly in flowing well conditions, it is essential to apply the suitable mud density since the aquifer can generates an overpressurized condition. This paper proposes a method for determining the suitable mud density while drilling (SMD) through confined aquifers using mud window analysis and applies it to a case study. The minimum mud density at each depth, which represents the lower limit of the mud window, is determined by the equivalent mud density pore pressure gradient (or by adding a trip margin) at that depth. The pore pressure gradient of a confined aquifer can be calculated using the piezometric level or well head pressure of the aquifer. As the borehole reaches the confined aquifer, there is a significant increase in pore pressure gradient, which gradually decreases with increasing depth. The SMD to prevent a kick can be determined as the maximum value among the minimum mud densities in the open hole section. After entering the confined aquifer, SMD is maintained as the minimum mud density at the top of the aquifer during the drilling of the open hole section. Additionally, appropriate casing installation can reduce the SMD, minimizing the risk of mud loss or invasion into the highly permeable aquifer.