• Economic and Environmental Geology
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• v.57 no.4
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• pp.353-362
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• 2024

This study examined the spectral characteristics of sediments according to moisture content using an unmanned aerial vehicle (UAV)-based hyperspectral sensor and evaluated the efficiency of moisture content detection at different flight altitudes. For this purpose, hyperspectral images in the 400-1000nm wavelength range were acquired and analyzed at altitudes of 40m and 80m for sediment samples with various moisture contents. The reflectance of the sediments generally showed a decreasing trend as the moisture content increased. Correlation analysis between moisture content and reflectance showed a strong negative correlation (r < -0.8) across the entire 400-900nm range. The moisture content detection model constructed using the Random Forest technique showed detection accuracies of RMSE 2.6%, R² 0.92 at 40m altitude and RMSE 2.2%, R² 0.95 at 80m altitude, confirming that the difference in accuracy between altitudes was minimal. Variable importance analysis revealed that the 600-700nm band played a crucial role in moisture content detection. This study is expected to be utilized in efficient sediment moisture management and natural disaster prediction in the field of environmental monitoring in the future.

• Korean Journal of Crystallography
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• v.13 no.1
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• pp.17-20
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• 2002

The complex [Zn(L)₂(H₂O)₄] (1) (L = isonicotinate) has been prepared and characterized by X-ray crystallography. Compound 1 crystallizes in the triclinic space group P1, with a = 6.9062(4) , b = 9.2618(7) , c = 6.3313(3) , α = 104.986(6)°, β = 112.865(4)°, γ = 96.213(6)°, V = 350.41(4) , Z = 1, R₁(wR₂) for 1225 observed reflections of [I > 2σ(I)] was 0.0209 (0.0591). The coordination environment of the zinc atom can be described as an octahedron in which the isonicotinato ligands are mutually trans. Compound 1 is also connected into a two-dimensional chain via hydrogen-bonds.

• Journal of the Korean Recycled Construction Resources Institute
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• v.9 no.4
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• pp.478-482
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• 2021

In this paper, methods for manufacturing shielding concrete by recycling steelmaking slag discarded as industrial waste and measuring the shielding effectiveness of the shielding concrete were studied. By comparing the result of shielding effectiveness measurement of this concrete block with shielding effectiveness measurement of the structure constructed with this concrete, the measurement system for measuring shielding effectiveness of the concrete block was verified. The size of the concrete stru ctu re is 2.9 × 2.9 × 3.4m and the concrete block is 0.3 × 0.3 × 0.2m. The frequ ency band u sed for mesu rement is 600MHz - 2GHz, the types of concrete u sed to measu re the shielding effectiveness are general concrete and concrete containing electric arc furnace oxidizing slag. In the case of the concrete structure, reinforcing rebars are installed at intervals of 15cm for stru ctu ral safety, as the frequ ency increase, the electromagnetic wave properties of rebars gradu ally decreased, there was a slight difference in the measurement results. In conclusion, the measurement result of shielding effectiveness of the concrete block is similar to the result of the concrete structure. It is thought that it can be sufficiently utilized for electromagnetic wave engineering design, and the concrete shielding effectiveness measurement system using standard specimens was verified.

• Journal of Mechanical Science and Technology
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• v.17 no.5
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• pp.758-765
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• 2003

An experimental investigation on the flow pattern and pressure drop was carried out for both an adiabatic and a diabatic two-phase flow in a horizontal tube with pure refrigerants R134a and R123 and their mixtures as test fluids. The observed flow patterns were compared to the flow pattern map of Kattan et al., which predicted well the present data over the entire regions of mass velocity in this study. The measured frictional pressure drop in the adiabatic experiments increased with an increase in vapor quality and mass velocity These data were compared to various correlations proposed in the past for the frictional pressure drop. The Chisholm correlation underpredicted the present data both for pure fluids and their mixtures in the entire mass velocity range of 150 to 600 kg/m$^2$s covered in the measurements, white the Friedel correlation was found to overpredict the present data in the stratified and stratified-wavy flow region, and to underpredict in the annular flow region.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.11 no.8
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• pp.596-600
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• 1998

A method for the nondestructive read-out of the memory in ferroelectric thin films is demonstrated using the detection second harmonic currents introduced in the ferrolelectric capacitor as a response to an ac signal. The sign and phase of the second harmonic current depends on the polarized state +$P_r or -P_r$, The studied ferroelectric PZT thin film is found to have desirable features for the use as a memory element. This method and material seems as a promising approach for the nonvolatile memory storage.

• Parasites, Hosts and Diseases
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• v.55 no.3
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• pp.337-340
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• 2017

Leishmaniasis is a neglected and endemic disease that affects poorest population mainly in developing countries. A lack of adequate and definitive chemotherapeutic agents to fight against this infection has led to the investigation of numerous compounds. The aim of this study was to investigate in vitro activity of boldine against Leishmania amazonensis murine cell infection. Boldine ((S)-2,9-dihydroxy-1,10-dimethoxy-aporphine) is an aporphine alkaloid found abundantly in the leaves/bark of boldo (Peumus boldus Molina), a widely distributed tree native to Chile. The in vitro system consisted of murine macrophage infection with amastigotes of L. amazonensis treated with different concentrations from 50 to $600{\mu}g/ml$ of boldine for 24 hr. Intracellular parasite destruction was assessed by morphological examination and boldine cytotoxicity to macrophages was tested by the MTT viability assay. When cells were treated with $100{\mu}g/ml$ of boldine the reduction of parasite infection was 81% compared with untreated cultures cells. Interestingly, boldine-treatment caused a concentration-dependent decrease of macrophage infection that culminated with 96% of reduction when cells were submitted to $600{\mu}g/ml$ of boldine. Cell cultures exposed to $100{\mu}g/ml$ of boldine and $300{\mu}g/ml$ of $Glucantime^{(R)}$ during 24 hr showed a significant reduction of 50% in parasitized cells compared with cell cultures exposed just to $Glucantime^{(R)}$. The study showed that treatment with boldine produces a better effect than treatment with the reference antimonial drug, glucantime, in L. amazonensis infected macrophage. Our results suggest that boldine is a potentially useful agent for the treatment of leishmaniasis.

• Journal of Advanced Marine Engineering and Technology
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• v.32 no.4
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• pp.534-541
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• 2008

This paper deals with the heat transfer characteristics of R-290 (Propane), R-600a (Iso-butane) and R-1270 (Propylene) as an environment friendly refrigerant and R-22 as a HCFC's refrigerant for evaporating. The experimental apparatus has been set-up as conventional vapor compression type refrigeration and air-conditioning system. The test section is a horizontal double pipe heat exchanger. Evaporating heat transfer measurements were performed for smooth tube with the outer diameters of 12.70, 9.52 and 6.35 mm and micro-fin tube 12.70 mm, respectively. For the smooth and micro-fin tubes measured in this study, the evaporating heat transfer coefficient was enhanced according to the increase of the mass flux and decrease of the tube diameter. The local evaporating heat transfer coefficients of hydrocarbon refrigerants were superior to those of R-22 and the maximum increasing rate of heat transfer coefficient was found in R-1270. The average evaporating heat transfer coefficients in hydrocarbon refrigerants showed 20 to 28% higher values than those of R-22. Also, the evaporating heat transfer coefficients of R-22 in the tube diameter of the 12.70 mm smooth and micro-fin tube were compared. Generally, the local heat transfer coefficients for both types of tubes increased with an increase of the mass flux. The heat transfer enhancement factor (EF) between smooth and micro-fin tube varied from 1.9 to 2.7 in all experimental conditions.

• Journal of the Earthquake Engineering Society of Korea
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• v.15 no.6
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• pp.55-66
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• 2011

The purpose of this study was to develop an efficient process in the design and construction of a 1:5 scale 10-story R.C. apartment building model for an earthquake simulation test. The reduction ratio of the specimen was determined by the size ($5m{\times}5m$) and pay load (600kN) of the available shaking table and the availability of model reinforcements. For efficiency and quality control of the reinforcement work, prefabrication was used. Construction was conducted in two steps, the wall in one step, and another step for the slab, because it was impossible to remove the formwork of a wall if the walls and slabs in a story were constructed in one step. The slip form construction method was used repetitively for walls. The formwork of a wall was made with veneer and acryl plate on each side, so it was possible to check the quality of the concrete placing. To construct this model, it took roughly six months with five full-time research assistants, for a total of 602 man days of labor in construction.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.36 no.6
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• pp.593-600
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• 2012

The exergy characteristics for R245fa and water working fluids have been analyzed for an electric generation system utilizing the Rankine cycle to recover heat from the wasted exhaust gas from a diesel engine used for the propulsion of a large ship. The theoretical calculation results showed that the efficiencies of exergy and system exergy improved as the turbine inlet pressure increased for R245fa at a fixed mass flow rate. Furthermore, the exergy destruction rates of the condenser and evaporator were relatively larger than those in other components. The exergy efficiency of the system increased with increasing mass flow rate. For a water working fluid, although the exergy destruction rate of the evaporator was similar to that for R245fa, the exergy loss rate varied significantly in response to variations in the pressure and mass flow rates at the turbine inlet.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.19 no.10
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• pp.726-734
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• 2007

In this study, lower flammability limits (LFLs) of three hydrocarbon refrigerants (R600a, R290, R1270) and two hydrofluorocarbon refrigerants (R152a, R32) and DME (RE170) are measured by the method proposed by ASTM E681-04 Standard. Flammability tests are carried out at three temperatures of $23^{\circ}C,\;60^{\circ}C\;and\;100^{\circ}C$ and relative humidity 50%. Test results show that the present data for isobutane and propane obtained at $23^{\circ}C$ are similar to those found in the literature, confirming indirectly the reliability of the present test method and facility. For propylene, R152a, and R32, LFLs found in the literature differ considerably. Especially, the deviation of LFL of propylene is more than 30% among the literature data. The present data for propylene, R152a, and R32 agree with either of the data sets available. As the temperature increases from $23^{\circ}C\;to\;100^{\circ}C$, LFLs of all refrigerants tested decrease. LFLs of most refrigerants tested in this study at $60^{\circ}C$ decrease by $0.1{\sim}0.3%$ as compared to those at $23^{\circ}C$. Also LFLs of most refrigerants tested in this study at $100^{\circ}C$ decrease by $0.1{\sim}0.3%$ as compared to those at $60^{\circ}C$.