• Journal of Korean Society of Water and Wastewater
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• v.28 no.1
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• pp.61-72
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• 2014

Study on effluent organic matter (EfOM) characteristic and removal efficiency is required, because EfOM is important in regard to the stability of effluents reuse, quality issues of artificial recharge and water conservation of aqueous system. UV technology is widely used in wastewater treatment. Many reports have been conducted on microbial disinfection and micro pollutant reduction with UV treatment. However, the study on EfOM with UV has limited because low/medium pressure UV lamp is not sufficient to affect refractory organics. The high intensity of pulsed UV would mineralize EfOM itself as well as change the characteristics of EfOM. Chlorine demand and DBPs formation is affected on the changed amounts and properties of EfOM. The objective of this study is to investigate the effect on EfOM, chlorine residual, and chlorinated DBPs formation with low pressure and pulsed UV treatment. The removal of organic matter through low pressure UV treatment is insignificant effect. Pulsed UV treatment effectively removes/transforms EfOM. As a result, the chlorine consumption is changed and chlorine DBPs formation is decreased. However, excessive UV treatment caused problems of increasing chlorine consumption and generating unknown by-products.

• Proceeding of KASS Symposium
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• 2006.05a
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• pp.102-109
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• 2006

The effects of wind fence on the pressure characteristics around low-rise building model were investigated experimentally. Flow characteristics of turbulences behind wind fence were measured using hot-wire anemometer. The wind fence characterize by varying the porosity of 0 %, 40 % and the distances from the wind fence from 1 H to 6 H with maintaining the uniform flow velocity of 6 m/s. We investigated the overall characterization of the low-rise building by measuring pressure seventy four on model. The effects of porosity fences varied with the porosity of the fence and measurement locations(1H-6H). The 0% porosity proved to be effective for the protection area of 4H to 6H, but the 40% porosity proved to be effective for the protection area of 1H to 6H. The low-rise building of front face was found to be best wind fence for decreasing the mean, maximum and minimum pressure fluctuation.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.19 no.8
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• pp.19-23
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• 2005

The target of this research is a design of constant and high efficiency driving system for a low pressure UV lamp. An UV lamp system is one of wide range electrical equipments for semiconductor manufacturing and sterilization, etc... It is essential the technique of constant output for high added value device. A design target of driving system for low pressure UV lamp of conversion efficiency is 90[%], UV lamp of output stability within ${\pm}7.5[%]$, and lamp power is over 200[W]. The results meet the target of this study well, and have a benefit of domestic market occupation and enable to export. And if protection circuits were developed, it increases the stability of a electronic ballast for UV lamps.

• Journal of the Korean Society of Physical Medicine
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• v.18 no.3
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• pp.113-119
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• 2023

PURPOSE: This study aimed to determine the effects of using a smartphone in the sitting position on the pelvic posture and the low back pressure pain threshold (PPT). METHODS: Thirty participants (15 women and 15 men) were recruited for this study. The participants were asked to sit in a normal sitting position without using a smartphone, followed by sitting while watching a video using a smartphone. The pelvic posture was measured using the back range of motion II (BROM II) device and a palpation meter. We measured PPT using the digital pressure algometer. RESULTS: Pelvic posterior tilting was significantly greater when sitting while using a smartphone relative to sitting without using a smartphone (p < .05). There was no significant difference in the height of the iliac crest when sitting while using a smartphone compared to sitting without using a smartphone (p > .05). The PPTs of L1, L3, and L5 were significantly lower when sitting while using a smartphone relative to sitting without using a smartphone (p < .05). CONCLUSION: Based on these results, it can be concluded that frequent smartphone use while sitting may potentially increase the risk of developing low back problems.

• Journal of the Korean Society of Combustion
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• v.21 no.4
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• pp.39-47
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• 2016

The aims of this research were to investigate combustion characteristics of lab-scale pressurized oxy-fuel combustion(POFC) system. In this study, the reactor, 800 mm long, was equipped with co-axial burner. Low calorific value syngas that is composed of mainly CO and $H_2$ was used as fuel whereas pure oxygen was used as an oxidant. Thermal heat input to the reactor varied from 2.6 kW to 6.1 kW. The reactor pressure also increases from atmospheric up to 15 bar. The results show that as the pressure increase, the temperature of reactor decreases on the whole in all cases. A significant temperature drop was observed especially at the bottom section of the reactor that exist flame. In addition, the flame instability increases as the pressure increases. Furthermore $NO_x$ emissions increases from atmospheric up to 2 bar. However beyond 2 bar, $NO_x$ emission reduces as pressure increases. Lastly $NO_2$ ratio in $NO_x$ also increases as pressure increases.

• 유체기계공업학회:학술대회논문집
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• 2002.12a
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• pp.183-190
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• 2002

In order to reduce NOx emissions in the 20kw class microturbines under development, the low NOx characteristics, as being an application to the lean premixed combustion technology, have been investigated. The study has been conducted at the conditions of high temperature and pressure. Air from a compressor with the temperature of 500K to 650K and the pressure of 0.3bar gauge to 0.7bar gauge, was supplied to the combustor through an air preheat-treatment. Sampling exhaust gases were measured at the immediate exit of the combustor. for the effect of temperature on NO and CO emissions. though NOx was increased, CO was decreased with increasing inlet air temperature. With increasing inlet air pressure, NOx and CO were increased also. NOx was decreased, but CO was increased with increasing inlet air mass flow rate. The test has been performed on the equivalent ratios of 0.10 to 0.25 in a lean region. NOx was increased with increasing equivalent ratios, but CO was decreased as an influence of flame temperature. In the very lean region of the equivalent ratio below 0.12, CO was increased suddenly, due to instability. As the results of this study, NOx and CO are found to be reduced to the similar level at the same time when operated at optimal conditions.

• Transactions of the Korean Society of Automotive Engineers
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• v.17 no.5
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• pp.31-38
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• 2009

Supercharging system was adopted to investigate the influence of boost pressure on operating range and exhaust emissions by using a supercharger at low temperature diesel combustion (LTC) condition in a 5-cylinder 2.7 L direct injection diesel engine. The experimental parameters such as injection quantity, injection timing, injection pressure and exhaust gas recirculation (EGR) rate were varied to find maximum operating range in LTC condition. As a result of adopting increased boost pressure in LTC, wider operating range was achieved compared with naturally aspirated condition due to increased mixing intensity. Increased boost pressure resulted in lower hydrocarbon (HC) and carbon monoxide (CO) emissions due to increased swirl rate and mixing intensity, which induced complete combustion. Moreover, increased boost pressure in LTC resulted in much lower soot emissions compared with high speed direct injection (HSDI) condition.

• Proceedings of the Korean Nuclear Society Conference
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• 1997.05a
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• pp.386-391
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• 1997

It is important to understand correctly a CHF under low flow condition for the purpose of enhancing the reactor safety and performance in the LWRs. The CHF experiments have been carried out for an internally heated vertical annulus in RCS loop facility. The experimental conditions cover ranges of pressure from 1.82 to 12.08 MPa, mass flux from 300 to 550kg/$m^2$. s and inlet subcooling of 210kJ/kg. The CHF data decrease with increasing pressure at high value of mass flux. For mass flux of about 300kg/$m^2$. s, the CHF rue little influenced by pressure. The CHF data are correlated well by using the dimensionless heat flux and dimensionless mass flux for a fixed inlet subcooling except the data group of 12.08 MPa. It seems that the Doerffer correlation and Katto correlation overestimate the CHF for low pressure and lower value of mass flux within this experimental ranges. The Bowling correlation gives a better prediction than the other two correlations.

• Textile Coloration and Finishing
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• v.25 no.1
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• pp.47-55
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• 2013

Physical properties of the composite yarn using low-melting(LM) polyester/Tencel were investigated with air-jet texturing conditions such as temperature, take-up overfeed, yarn speed and air pressure. Surface morphology, microstructure, tensile property, glossiness were evaluated. Surface morphology of a composite yarn had more damaged and loosened structure according to increase of take-up overfeed, yarn speed and air pressure. Crystallinity was affected by parameters such as temperature, yarn speed, take-up overfeed and air pressure and especially, yarn speed was most effective for increase of crystallinity. Also, it was found that temperature and air pressure had significantly affected tensile properties of a composite yarn. The glossiness of yarn increased with increase of temperature, yarn speed and air pressure.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2009.11a
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• pp.439-442
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• 2009

In this study, the residual strength of CFRP filament winding pressure vessel after low velocity impact was evaluated quantitatively. After impact test, the pressure vessel was sectioned to produce 25 mm-wide ring specimen and the bursting pressure of this specimen was measured. A finite element model was also fabricated to investigate the deformation and stress distribution characteristics of the impacted CFRP vessel. The degradation of the residual strength along with the increase of impact energy was successfully measured and reviewed.