• Journal of the Korean Association of Geographic Information Studies
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• v.27 no.2
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• pp.61-77
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• 2024

The purpose of this study was to develop a method for rapidly diagnosing urban thermal comfort using Unmanned Aerial Vehicle (UAV) based data. The research was conducted at Changwon National University's College of Engineering site and Yongji Park, both located in Changwon, Gyeongsangnam-do. Baseline data were collected using field measurements and UAVs. Specifically, the study calculated field measurement-based thermal comfort indices PET and UTCI, and used UAVs to create and analyze vegetation index (NDVI), sky view factor (SVF), and land surface temperature (LST) images. The results showed that UAV-predicted PET and UTCI had high correlations of 0.662 and 0.721, respectively, within a 1% significance level. The explanatory power of the prediction model was 43.8% for PET and 52.6% for UTCI, with RMSE values of 6.32℃ for PET and 3.16℃ for UTCI, indicating that UTCI is more suitable for UAV-based thermal comfort evaluation. The developed method offers significant time-saving advantages over traditional approaches and can be utilized for real-time urban thermal comfort assessment and mitigation planning

• Journal of the Korean Chemical Society
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• v.25 no.5
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• pp.306-310
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• 1981

Induced circular dichroism spectra of racemic cobalt(III) complexes for $[Co(en)_3]^{3+},\;[Co(tn_)3]^{3+},\;cis-[Co(NH_3)(en)_2]^{3+},\;[Co({\beta}-ala)(en)2_]^{2+},\;[Co(gly)(en)_2]^{2+}\;and\;[Co(acac)(en)_2]^{2+}$ were measured when they were dissolved in aqueous d-tartrate2- solution at room temperature. Only a single negative CD spectrum was observed for all the complexes above in visible region(400∼500nm). It was interpreted that these CD bands were attributed to the difference in interaction between ${\Lambda}$-and ${\Delta}$-enantiomers with d-tartrate$^{2-}$. Namely, when d-tartrate$^{2-}$ was added to ${\Lambda}$-enantiomer and ${\Delta}$-enantiomer, it caused ${\Lambda}$-enantiomer to change greatly and ${\Delta}$-enantiomer to change only slightly; combined the results proved induced circular dichroism. The enantiomer for which the eluent has a stronger affinity should be eluted faster in ion-exchange column chromatography. It is possible to predict the elution order of chromatography from the sign of the induced CD if stronger interaction of chiral anion with the complex leads to greater change in the natural CD spectrum of the complex. The elution order was in complete agreement with the prediction from the sign of the induced CD spectrum for all the measured complexes.

• Composites Research
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• v.31 no.1
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• pp.30-36
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• 2018

The curing behavior of glass fiber reinforced epoxy prepregs based on Bisphenol-A (BPA) was studied by differential scanning calorimetry (DSC). The total heat of reaction(${\Delta}H_{total}=280.3J/g$) was determined based on the results of the dynamic heating scanning experiments. Isothermal experiments were carried out at $110{\sim}130^{\circ}C$, and it was observed that the maximum conversion and the maximum reaction rate were increased as temperature increased. Also Kamal equation was applied to analyze autocatalytic reaction of epoxy prepregs. The higher temperatures, the greater reaction rate constants ($k_1$, $k_2$). Theoretical values were calculated by these reaction rate constants and compared with experimental values. And it was confirmed that they were in reasonable agreement. At the beginning of the reaction, the experimental data and theoretical prediction were shown the same tendency, but at the end of reaction, the experimental data were smaller than theoretical predicted values due to reaction rates controlled by diffusion.

• Journal of Marine Bioscience and Biotechnology
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• v.2 no.3
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• pp.160-167
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• 2007

Shelf-stability of powdered model food was determined during storage at various temperatures ($25^{\circ}C$, $35^{\circ}C$) and various moisture contents (3.5%, 6.0%, 8.0%). Moisture content, peroxide value, pH, color, microbial counting and sensory evaluation were conducted during storage. Moisture content, peroxide value, pH and color were not significantly changed during storage in all samples indicating that this powdered model food was relatively stable at given conditions. Pathogenic microorganisms, such as Bacillus cereus, Listeria spp., Clostridium perfrigens, Salmonella spp. and Staphylococcus aureus, were not found during storage suggesting that there was no problem in safety in this case. On the other hand, the number of artificially added Lactic acid bacteria was decreased with increasing both storage temperature and moisture content. Therefore, powdered model food was very shelf-stable and it was impossible to predict the shelf-life using above quality factors.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.46 no.3
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• pp.195-201
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• 2001

Sowing date experiments were carried out by employing a rice variety "Kwanganbyeo" in both field and phytotron with natural daylength. In phytotron, temperatures were controlled at daily mean of 21$^{\circ}C$ and 24$^{\circ}C$. The responses of final leaf number and beading date were analyzed in relation to daylength during photo-sensitive period (PSP). Based on the component models predicting the final leaf number and leaf appearance rate, a rice phenology model was established and verified. Days from sowing to flowering (DSF) were shortened and final number of leaves (FNL) increased as sowing dates were delayed from 25 April to 5 June in field and phytotron. The increased leaf appearance rate (LAR) and the reduced FNL, respectively, due to the higher temperature and the shorter daylength in delayed sowings in the field brought about greater shortening of DSF than in the phytotron where only FNL was reduced by shorter daylength in delayed sewings. FNL showed very close relationship with the average daylength during PSP of six-leaf stage to panicle initiation, being well fitted to the following rational function ($R^2$=0.98):(equation omitted) where D is daylength and a, b, and c are the constants that were estimated as 14.694, -0.992, and -0.068 in Kwanganbyeo, respectively. The rice phonology model, which was composed of two component models for LAR and FNL, predicted DSF very accurately. The differences between the observed and predicted DSF was less than two days in the sewing date field experiments in 1999 and 2000 of which data were not used for the model construction.struction.

• Journal of the Korean earth science society
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• v.34 no.7
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• pp.645-661
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• 2013

The synoptic, thermodynamic, and dynamic characteristics of a heavy snowfall event that occurred in Seoul metropolitan area on 27 to 28 December 2010 was investigated. During this period there was a distinctive case that was identified as a polar low. We analyzed surface and upper level weather charts, snowfall amount, sea surface temperature, satellite imagery, sounding, and the National Center for Environmental Prediction global $1^{\circ}{\times}1^{\circ}$ reanalysis data. The polar low developed in an area where there was strong baroclinicity in the lower level aided by strong conditional instability due to 925 hPa warm air advection and 700 hPa cold air advection. The development mechanism of polar low is due, in part, to the tropopause folding, which advected stratospheric air increasing potential vorticity in mid-level and inducing cyclonic vorticity and convergence in low-level. Eventually clouds developed and there were snowfall total of 10 cm in Seoul metropolitan area and as much as 20 cm in southern parts of Korea. During the snowfall development, there was a $-45^{\circ}C$ cold core at 500 hPa and shortwave maintained $3-5^{\circ}$ separation with surface trough, which favored the development of polar low located in the warm sector and cyclonic advection area. The height of the dynamical tropopause lowered to 700 hPa during the peak development and increase in potential vorticity allowed strong vertical motion to occur. Overall, there was a close relationship between the development of snowfall and tropopause undulation. The heaviest snowfall occurred east of the tropopause folding where strong cyclonic vorticity, vertical motion, and moisture advection all coincided while the polar low was passing through the Korean peninsula.

• Journal of the Korean Institute of Intelligent Systems
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• v.26 no.3
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• pp.182-189
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• 2016

For high accuracy of forecast using numerical weather prediction models, we need to get weather observation data that are large and high dense. Korea Meteorological Administration (KMA) mantains Automatic Weather Stations (AWSs) to get weather observation data, but their installation and maintenance costs are high. Mini-AWS is a very compact automatic weather station that can measure and record temperature, humidity, and pressure. In contrast to AWS, costs of Mini-AWS's installation and maintenance are low. It also has a little space restraints for installing. So it is easier than AWS to install mini-AWS on places where we want to get weather observation data. But we cannot use the data observed from Mini-AWSs directly, because it can be affected by surrounding. In this paper, we suggest a correcting method for using pressure data observed from Mini-AWS as weather observation data. We carried out preconditioning process on pressure data from Mini-AWS. Then they were corrected by using machine learning methods with the aim of adjusting to pressure data of the AWS closest to them. Our experimental results showed that corrected pressure data are in regulation and our correcting method using SVR showed very good performance.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.10
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• pp.182-188
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• 2016

A decoy is a weapon system that can protect vessels from an enemy's torpedo. Thus, the decoy should be able to operate in the field without any failure. Because the decoy can be inoperable once its sealing is broken and water permeates inside the system, the hermetic sealing capability considering the operational environment is mandatory. To be hermetically sealed, a rubber-type O-ring is generally used in a decoy system. The sealed performance of rubber-type products, however, tends to age and deteriorate with time. Therefore, the O-ring needs to be maintained or changed periodically. This paper proposes a method to estimate the proper maintenance period using the hardness and elongation percentage, which represents the performance of the O-ring product and test data from Accelerated Life Test (ALT) of the product. The O-ring used in this paper is a NBR type, and the temperature was chosen to be the main accelerating factor as referenced in many studies. The criteria for the failure of the O-ring was set for the product to be 50% degraded compared to the initial performance. In addition, the Korean standard KS M 6518 was adopted and referenced for the preparation of test samples and the calculation of estimates. The O-ring's predicted life was simulated by analyzing the test results from a computer program, and the optimized maintenance period for the product was determined.

• Journal of the Korea institute for structural maintenance and inspection
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• v.25 no.6
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• pp.111-120
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• 2021

When a fire occurs in a commercial building, the evacuation route is complicated and the direction of smoke and flame is similar to that of the egress route of occupants, resulting in many casualties. Performance-based evacuation design for buildings is essential to minimize human casualties. In order to apply the performance-based evacuation design to buildings, it requires a complex fire simulation for each building, demanding a large amount of time and manpower. In order to supplement this, it would be very useful to develop an Available Safe Egress Time (ASET) prediction model that can rationally derive the ASET without performing a fire simulation. In this study, the correlations between fire temperature with visibility and toxic gas concentration were investigated through a fire simulation on a commercial building, from which databases for the training of artificial neural networks (ANN) were created. Based on this, an ANN model that can predict the available safe egress time was developed. In order to examine whether the proposed ANN model can be applied to other commercial buildings, it was applied to another commercial building, and the proposed model was found to estimate the available safe egress time of the commercial building very accurately.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.32 no.2
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• pp.103-108
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• 2019

Non-equilibrium molecular dynamics simulation on the thermal boundary resistance(TBR) of an aluminum(Al)/silicon(Si) interface was performed in the present study. The constant heat flux across the Si/Al interface was simulated by adding the kinetic energy in hot Si region and removing the same amount of the energy from the cold Al region. The TBR estimated from the sharp temperature drop at the interface was independent of heat flux and equal to $5.13{\pm}0.17K{\cdot}m^2/GW$ at 300K. The simulation result was experimentally confirmed by the time-domain thermoreflectance technique. A 90nm thick Al film was deposited on a Si(100) wafer using an e-beam evaporator and the TBR on the film/substrate interface was measured using the time-domain thermoreflectance technique based on a femtosecond laser system. A numerical solution of the transient heat conduction equation was obtained using the finite difference method to estimate the TBR value. Experimental results were compared to the prediction and discussions on the nanoscale thermal transport phenomena were made.