• 대한정형도수물리치료학회지
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• 제14권1호
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• pp.31-38
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• 2008

Purpose : The purpose of this study was to compare the effectiveness of both neuromuscular electrical stimulation(NMES) and isometrical exercise(IE) to strengthen the quadriceps femoris muscle. The relationships between the strength changes and the relative force and duration of training contractions were also studied. Methods : The subjects were divided into three group. The control group(n=6) received no exercise and/or stimulation. The isometric exercise (IE) group(n=6) performed maximum isometric contractions, and the neuromuscular electrical stimulation(NMES)(n=6) engaged electrically stimulated isometric contractions, three days a week for four weeks. Results : Results showed that both IE group and NMES group were found to have an increase in strength significantly greater(p<0.05) than the control group at 4 week. But between IE group and NMES group were not found to have an difference in strength significantly. Conclusion : The relative increase in isometric strength, using IE and NMES, may be determined by the ability of the subjects to tolerate longer and more forceful contractions. Suggestions for further research and implications for the clinical of IE and NMES for strength-training are discussed.

• Applied Science and Convergence Technology
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• 제25권6호
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• pp.124-127
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• 2016

Humidity calibration for a temperature-stable quartz oscillator (TSQO) was investigated to exclude the influences of relative humidity on the TSQO output in order to use the corresponding devices outdoors. The TSQO output is a voltage that is inversely proportional to the electric impedance of the quartz oscillator, which depends on the viscosity and density of the measured gas. The TSQO output was humidity calibrated using its humidity dependence, which was obtained by varying the relative humidity (RH) from 0 to 100 RH% while other conditions were kept constant. The humidity dependencies of the TSQO output were fit by a linear function. Subtracting the change in the TSQO output induced by the change in humidity, calculated with the function from the experimentally measured TSQO output for a range of 0-100RH%, eliminated the influence of humidity on the TSQO output. The humidity calibration succeeded in reducing the fluctuations of the TSQO output from 0.4-3% to 0.1-0.3% of the average values for a range of 0-100RH%, at constant temperatures. The necessary stability of the TSQO output for application in hydrogen sensors was below one-third of the change observed for a hydrogen leakage of 1 vol.% hydrogen concentration, corresponding to 0.33% of the change in each background. Therefore, the results in this study indicate that the present humidity calibration effectively suppresses the influence of humidity, for the TSQO output for use as an outdoor hydrogen sensor.

• 한국해양공학회:학술대회논문집
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• 한국해양공학회 2004년도 학술대회지
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• pp.247-252
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• 2004

To secure stability and availability of Rammed Aggregate Pier method as the foundation of a structure, the bearing capacity and failure behavior characteristics was studied through soil laboratory tests in a model ground. In this study, soil laboratory tests use carried out to find the applicability of RAP method as the foundation of a structure. And bearing capacity and the failure mechanism of RAP method was studied according to relative density($60\%,\;70\%,\;90\%$), diameter(45mm, 60mm, 70mm) of each pier ana depth(5cm, l0cm, 15cm, 20cm, 25cm, 30cm). Earth pressure cell is set up approach RAP and 1.0D space at RAP center. Bearing acpacity and the failure mechanism of RAP is investigated by load test As a result, bulging failure was happened in $5\~10cm\;(1.0D\~2.00)$ depth which the maximum lateral earth pressure is acting. Especially, diameter changing of RAP are in inverse proportion to the relative density and the lateral stress is very much influenced by the lateral earth pressure in every layer and tends to decrease according to depth.

• 대한기계학회논문집B
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• 제33권8호
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• pp.604-612
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• 2009

Water management has been recognized as a crucial factor for achieving better performance and stability in polymer electrolyte membrane fuel cells (PEMFCs). Proper water management should provide favorable water conditions, including the local humidity, membrane water content, and liquid water saturation in PEMFCs, thereby leading to more uniform electrochemical reaction and current generation. In this study, computational fluid dynamics (CFD) simulation was conducted to investigate the effects of the cathode relative humidity (RH) on the performance of a 3 by $3\;cm^2$ PEMFC with serpentine flow fields. The CFD results showed that the best performance of the PEMFC was obtained for the cathode RH of 80%, but the performance variation was small for the cathode RH range of $60{\sim}100%$. However, the loss of the PEMFC performance was significant when the cathode RH was reduced below 40%. The reason for such performance variation was investigated through the detailed inspection of ohmic loss, activation and concentration overpotential, and water and current distributions.

• 한국연소학회지
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• 제10권4호
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• pp.33-40
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• 2005

The propagation rates of advancing and retreating non-premixed edge flames in a slot-jet counterflow were measured as a function of strain rate for varying jet spacing, mixture strength, stoichiometric mixture fractions $(Z_{st})$ and Lewis numbers (Le). Methane and propane fuels were tested and nitrogen and carbon dioxide were used as inerts. As results, we could identify igniting fronts, retreating fronts, two total extinction limits, and short-length edge flames. A burner separation affected to a low extinction limit only. Regimes for advancing and retreating edges together with total extinction were mapped in terms of normalized flame thickness and heat loss factor for $CH_4/O_2/N_2$ mixtures. Edge flames for $Z_{st}$ > 0.5 behaved like a stronger mixture while for $Z_{st}$ < 0.5 showed deteriorated feature, because of relative locations of a non-premixed flame and intermediate species such as CO and $H_2$. Furthermore, due to the relative importance of heat loss, propagating speeds of edge flames were significantly enhanced in $CH_4/O_2/CO_2$ mixtures (Le < 1) demonstrating increasing stability limits. However $C_3H_8/O_2/N_2$ mixtures (Le > 1) showed opposite result.

• 자원환경지질
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• 제7권4호
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• pp.175-184
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• 1974

Weathering of granites has a great geochemical significance, because of their chemical stability near the earth surface which is more pronounced than in most other rocks. The author intended to observe the relative mobility of major elements in weathering process of the granite, distributed on outskirts of Iri city Jeolla-bugdo, Korea. He analysed fresh granites and weathered ones from the Baeg-Gu granite mass and obtained following conclusions in the triangle-diagrams and the oxidized variation diagrams of the samples. 1) The increasing phenomena of $H_2O$ was observed clearly in early and late stages of weathering process. 2) The early stage of weathering is commenced by physical weathering and followed by chemical weathering. 3) The ratio of $FeO/Fe_2O_3$, FeO/MgO, and $SiO_2/Al_2O_3$ decreased uniformly from early to late stage of weathering processes. 4) It was proved that weathering potential of granite was larger than that of basaltic rock. 5) The order of mobility in major elements was Ca, Na and K

• 한국의류학회지
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• 제45권2호
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• pp.305-316
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• 2021

In this study, the effect of wearing functional compression pants is verified using a lower-limb wearable robot through a bio-signal analysis and subjective fit evaluation. First, the compression area to be applied to the functional compression pants is derived using the quad method for nine men in their 20s. Subsequently, functional compression pants are prepared, and changes in Electroencephalogram (EEG) and Electrocardiogram (ECG) signals when wearing the functional compression and normal regular pants inside a wearable robot are measured. The EEG and ECG signals are measured with eyes closed and open. Results indicate that the Relative alpha (RA) and Relative gamma wave (RG) of the EEG signal differ significantly, resulting in increased stability and reduced anxiety and stress when wearing the functional compression pants. Furthermore, the ECG analysis results indicate statistically significant differences in the Low frequency (LF)/High frequency (HF) index, which reflect the overall balance of the autonomic nervous system and can be interpreted as feeling comfortable and balanced when wearing the functional compression pants. Moreover, subjective sense is discovered to be effective in assessing wear fit, ease of movement, skin friction, and wear comfort when wearing the functional compression pants.

• The Journal of Asian Finance, Economics and Business
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• 제8권2호
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• pp.725-735
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• 2021

This study investigates whether the Islamic Exchange-Traded Funds (ETFs) provide significant benefit to investors relative to conventional ETFs. Six pairs of Islamic and conventional ETFs with 10-year daily price data from 2010 to 2019 have been selected from major market indices like MSCI World Index, MSCI Emerging Markets, MyETF Dow Jones Islamic Market Malaysia, MSCI South East Asia and Wahed FTSE Shariah USA Index for this study. For ETFs that are launched after 2010, the price data from launch date to 2019 are used. Our results show: First, Islamic ETFs are more likely to trade at a premium rather than at a discount, implying the investors are willing to pay a premium. Second, it is also found that Islamic ETFs have a relatively shorter period of price deviation from the benchmark, implying more price stability. Third, conventional ETFs have higher return and lower tracking errors relative to Islamic ETFs. These new findings add to the stylized facts of Islamic ETFs in the extant literature for investors, plan sponsors and regulators as to the differences between the ETFs. As policy suggestion, asset management companies can design new investment products to bridge the gap between conventional and Islamic finance.

• 한국분말재료학회지
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• 제30권5호
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• pp.436-441
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• 2023

Molybdenum-tungsten (Mo-W) alloy sputtering targets are widely utilized in fields like electronics, nanotechnology, sensors, and as gate electrodes for TFT-LCDs, owing to their superior properties such as high-temperature stability, low thermal expansion coefficient, electrical conductivity, and corrosion resistance. To achieve optimal performance in application, these targets' purity, relative density, and grain size of these targets must becarefully controlled. We utilized nanopowders, prepared via the Pechini method, to obtain uniform and fine powders, then carried out spark plasma sintering (SPS) to densify these powders. Our studies revealed that the sintered compacts made from these nanopowders exhibited outstanding features, such as a high relative density of more than 99%, consistent grain size of 3.43 ㎛, and shape, absence of preferred orientation.

• 한국군사과학기술학회지
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• 제27권3호
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• pp.428-435
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• 2024

The important factors in the design of the gun propellant are impetus, flame temperature and pressure. In this paper, we considered a nitrocellulose based propellant composition that replaced sensitive NG(Nitroglycerin) with RDX(Cyclotrimethylenetrinitramine) and DEGDN(Diethylene glycol dinitrate) which high energy and low sensitivity. Particle size and content of RDX are the two main factors that affect the burning stability of RDX-based propellants. Among them, the characteristics of the propellant according to the particle size of RDX were confirmed. The relative combustion rate(R.Q., Relative Quickness) of the propellant changed according to the RDX particle size, and internal ballistics of properties of propellant were also varied. The particle size of RDX can be confirmed as a major factor in the combustion and internal ballistics characteristics of the propellant.