• Science of Emotion and Sensibility
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• v.14 no.4
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• pp.545-554
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• 2011

In this study, the parameters of Polysomnography (PSG) test, such as total sleep time, snoring time, had been analyzed to evaluate the effectiveness of a developed anti-snore pillow. The developed anti-snore pillow is made up of two polyvinylidene fluoride (PVDF) vibration sensors, pumps, valves, and air bladders. The two PVDF sensors inside the pillow can acquire the sound signals and the algorithm was perfectly designed to extract snoring by removing unwanted noise accurately and automatically. Once the pillow recognizes snore, a pump inside the hardware activates, and a bladder under the neck area inside the pillow will be inflated. The PSG test was used and two volunteers were participated for the study. The parameters of the PSG results were analyzed to evaluate the effectiveness of the anti-snore pillow. The total sleep time of each volunteer was similar on each phase of test, but the snoring time and the longest snoring episode were significantly decreased with the use of anti-snore pillow. The overall results showed excellent possibilities for reducing snoring for the person who snores during sleep by using the anti-snore pillow. The effectiveness of the anti-snore pillow can be evaluated by the PSG test. Moreover, the relationship between each parameter of PSG test and the quality of sleep will be used for further researches.

• Analytical Science and Technology
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• v.28 no.5
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• pp.353-360
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• 2015

Boiling is an efficient removal method to reduce radon in groundwater when ventilating indoor air. 13 groundwater samples with various radon concentrations were used to evaluate the reduction rate of radon with heating temperature and time. The groundwater samples were obtained by Bladder pump and on-situ measurements such as dissolved oxygen (DO) and hydrogen concentration (pH) and so on were carried out by a flow cell system isolated from the ambient atmosphere environment. All samples for measuring radon in groundwater were analyzed by liquid scintillation counter (LSC). The experiment result showed that increasing groundwater temperature enhanced radon removal rate but the initial radon concentration with high level lowered the removal rate. This means that radon reduction in groundwater by heating needs more heating energy and longer heating time with radon concentrations. Radon removal rate in groundwater, therefore, mainly depends on the initial radon concentration, heating temperature, and heating time.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.11
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• pp.355-362
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• 2016

The pipe material is selected according to the physical and chemical properties of the fluid flowing within it. Because the fluid used in fire extinguish systems is water, the various foreign substances dissolved in it cause scale to form on the pipe wall and accelerate the corrosion and aging of the pipe itself. This results in an increase in the friction loss and eventually degrades the efficiency of the pump. The use of CPVC (Chlorinated Poly-Vinyl Chloride) pipes was confirmed to reduce the friction loss compared to conventional steel pipes in the design and construction stages. The friction loss was found to be 76.64MPa with a C-value of 120 for the steel pipe and 50.72 MPa with a C-value of 150 for the CPVC pipe in an actual apartment construction environment. It was confirmed that the friction loss was improved by about 34% when using the CPVC pipe. When the steel and CPVC pipes were employed in the construction, the construction costs were 1,585,158 and 931,842 won, respectively. Therefore, it was shown that the construction cost was reduced by about 41%. We investigated the safety of the fire extinguishing system and the improvement in the economic performance due to the reduction in the total installed capacity by studying practical applications in the field.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.40 no.1
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• pp.39-45
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• 2016

Thermal management of a fuel cell is important to satisfy the requirements of durability and efficiency under varying load conditions. In this study, a linear state feedback controller was designed to maintain the temperature within operating conditions. Due to the nonlinearity of automotive fuel cell system, the state feedback controller results in marginal stable under load condition from $0.5A/cm^2$ to $0.7A/cm^2$. A PWM (Pulse Width Modulation) and the modified state feedback controller are applied to control the temperature under the load condition from $0.5A/cm^2$ to $0.7A/cm^2$. The cooling system model is composed of a reservoir, radiator, bypass valve, fan, and a water pump. The performance of the control algorithm was evaluated in terms of the integral time weighted absolute error (ITAE). Additionally, MATLAB/SIMULINK$^{(R)}$ was used for the development of the system models and controllers. The modified state feedback controller was found to be more effective for controlling temperature than other algorithms when tested under low load conditions.

• Journal of Chest Surgery
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• v.40 no.4 s.273
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• pp.273-279
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• 2007

Background: We evaluate the efficacy of ultra-hydrophilic coated bypass circuits in comparison with uncoated bypass circuits in a porcine cardiopulmonary bypass model. Material and Method: Normothermic cardiopulmonary bypass was peformed in 10 anesthetized pigs via the left atrium and ascending aorta with a centrifugal biopump. Ultra-hydrophilic coated bypass circuits wore used in 5 pigs (the study group) and uncoated bypass circuits were used for the control group. Platelet counts and platelet aggregation tests were peformed. The thrombin-antithrombin(TAT) complex level and total protein level were evaluated. Result: There were no significant changes En the platelet counts and aggregation ability of both groups. The TAT complex levels were not different between the two groups. The total protein level was significantly lower in the control group after cessation of cardiopulmonary bypass. Conclusion: The clinical effects of ultra-hydrophilic coating circuits were not remarkable, in terms of reducing inflammatory reaction and protection of platelet function. However, the effect of protection for blood protein adsorption might be acceptable.

• Progress in Medical Physics
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• v.13 no.2
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• pp.98-103
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• 2002

The purpose of this study was to evaluate the absorbed dose to the coronary artery segment from various sized balloon angio catheters. The liquid form of Ho-166 was produced at the KAERI by (n, ${\gamma}$ ) reaction. We used GafChromic film for the estimation of the absorbed dose by beta particles. The exposed films were read using a videodensitometer. Several film exposures were made with varying irradiation times and activities. A modified micrometer was used for the measurement of the absorbed dose distribution near the balloon surface. Four balloons of coronary catheters evaluated were 30 m long and 2.5, 3.0, 3.5 and 4.0 mm in diameter. All doses are plotted in units of Gy/min/GBq/ml as a function of radial distance in mm from the surface of balloon. The absorbed dose rate was 0.86, 1.01, 1.11 and 1.24 Gy/min/GBq/ml at a balloon surface for various balloon diameter 2.5, 3.0, 3.5 and 4.0 mm respectively. Using a vacuum pump, the air in the balloon was evacuated prior to instillation of the Ho-166 source. By removing air bubbles in the balloon, the absorbed dose distribution was more uniform.

• Journal of the Korean association of regional geographers
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• v.19 no.4
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• pp.615-626
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• 2013

In this study, spatial patterns of the urban flood vulnerability index in Seoul are examined by considering climate exposure, sensitivity, and adaptability associated with floodings for recent 5 year (2006~2010) period by the smallest administrative unit called Dong. According to the results of correlation analyses based on the IPCC(Intergovernmental Panel on Climate Change)'s vulnerability model, among many variables associated with urban flooding, rainwater tank capacity, 1-day maximum precipitation and flood pumping station capacity have statistically-significant, and relatively-high correlations with the number of flood damage in Seoul. The flood vulnerability map demonstrates that the extensive areas along Anyang and Joongnang streams show relatively high flood vulnerability in Seoul due to high sensitivity. Especially in case of Joongnang stream areas, climatic factors also contribute to the increase of flood vulnerability. At local scales, several Dong areas in Gangdong-gu and Songpa-gu also show high flood vulnerability due to low adaptability, while those in Gangnam-gu do due to high sensibility and climate factor such as extreme rainfall events. These results derived from the flood vulnerability map by Dong unit can be utilized as primary data in establishing the adaptation, management and proactive policies for flooding prevention within the urban areas in more detail.

• Applied Chemistry for Engineering
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• v.18 no.1
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• pp.29-35
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• 2007

Recently, due to narrow margin on design factor of flue gas desulfurization (FGD) systems or aging of systems, some problems such as decrease of $SO_2$ removal efficiency and difficulty on coping with unstable state are arising on FGD systems. On this study, to cope with these problems several methods such as adjustment of reagent pH, inlet $SO_2$ concentration, variation of units of operation pump, installation of liquid distribution ring (LDR) were attempted to increase the $SO_2$ removal using spray type simulated FGD system. Also, sulfite and Al/Fx ion effects on limestone blinding were experimented. When three absorber recirculation pumps were operated, $SO_2$ removal was increased by 12% in comparison with that of two pumps operation. $SO_2$ removal was increased by 2~7% after installation of LDR. Dissolved oxygen increased up to 0.5 ppm and limestone binding effect was alleviated after injection of dibasic acid (DBA) with the concentration of 500 and 1,000 ppm. When $Al^{3+}$ and $F^-$ ions were coexisting, the dissolution rate of limestone was decreased by 20%.

• Journal of the Korean Society for Marine Environment & Energy
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• v.12 no.3
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• pp.143-150
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• 2009

Fuel oil mostly used for a ship is made from crude oil by refining process. In order to produce plenty of high-quality fuel oil, the Fluid catalytic cracking(FCC) method is widely adopted to many refinery factories during the decomposition process from high molecule into lower molecule. The major constituents in spent FCC catalysts are Si, Al, Fe, Ti, alkali metals and some others. The spent catalyst is also composed small amounts of rare metals such as Ce, Nd, Ni and V. The big problem in FCC oil is mixing the catalyst in the oil. This reason is unstable separation of FCC catalyst in separator. Such a FCC catalyst will become a reason of heavy wear down in moving parts of engine. The impurity in oil is ash and deposit compound, such as Al, Si, Ni, Fe and V, which will accelerate the wear down on fuel pump, fuel injection valve cylinder liner and piston ring. It is important to find a basic reason of an engine trouble for preventing similar troubles anymore. Insurance compensation will be different according to the reason of an engine trouble which might be natural abrasion or other external causes. In this study, types and reasons of engine troubles related to fuel oil will be covered.

• Korean Chemical Engineering Research
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• v.55 no.6
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• pp.762-766
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• 2017

Energy recovery device (ERD) is used to save energy consumption in seawater reverse osmosis processes. However, small-scale ERDs (<$100m^3/d$) are hardly observed in seawater desalination market. In South Korea, most of seawater desalination plants for drinking water production are small-scaled and have been operated in island areas or on ships. Thus, the effect of ERDs for these small-scale SWRO processes should not be neglected. In this work, the small-scale SWRO processes are designed and analyzed in terms of energy consumption with/without ERD. The realistic efficiencies of high pressure pumps are considered for the energy analyses. The unit cost of electricity depending on the application place (e.g., inland and island areas, on ships) is investigated to calculate the energy cost for unit water production in various SWRO applications classified by plant capacity, application place, and the installation of ERD. As a result, the energy cost can be saved up to $1,640.4KRW/m^3$ when ERD is applied, and the saving effect increases at smaller plants on ships. In conclusion, the development of small-scale ERDs are necessary because small-scale SWRO processes are dominant in Korean seawater desalination market, and the electricity saving effect becomes higher at smaller-scaled system.