• International conference on construction engineering and project management
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• 2013.01a
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• pp.279-286
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• 2013

This paper introduces a new method for identification of building energy performance problems. The presented method is based on automated analysis and visualization of deviations between actual and expected energy performance of the building using EPAR (Energy Performance Augmented Reality) models. For generating EPAR models, during building inspections, energy auditors collect a large number of digital and thermal imagery using a consumer-level single thermal camera that has a built-in digital lens. Based on a pipeline of image-based 3D reconstruction algorithms built on GPU and multi-core CPU architecture, 3D geometrical and thermal point cloud models of the building under inspection are automatically generated and integrated. Then, the resulting actual 3D spatio-thermal model and the expected energy performance model simulated using computational fluid dynamics (CFD) analysis are superimposed within an augmented reality environment. Based on the resulting EPAR models which jointly visualize the actual and expected energy performance of the building under inspection, two new algorithms are introduced for quick and reliable identification of potential performance problems: 1) 3D thermal mesh modeling using k-d trees and nearest neighbor searching to automate calculation of temperature deviations; and 2) automated visualization of performance deviations using a metaphor based on traffic light colors. The proposed EPAR v2.0 modeling method is validated on several interior locations of a residential building and an instructional facility. Our empirical observations show that the automated energy performance analysis using EPAR models enables performance deviations to be rapidly and accurately identified. The visualization of performance deviations in 3D enables auditors to easily identify potential building performance problems. Rather than manually analyzing thermal imagery, auditors can focus on other important tasks such as evaluating possible remedial alternatives.

• Journal of Korean Society on Water Environment
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• v.39 no.6
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• pp.439-450
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• 2023

The Yeongsan River, a major water resource for Jeollanam-do, that is adjacent to industrial complexes and agricultural areas, is exposed to water pollution. Therefore, it is necessary to investigate the impact of water pollution incidences and prepare response systems for river environment safety for other water resources in the future. Environmental Fluid Dynamics Code (EFDC) was applied to the mainstream of the Yeongsan River where residential, commercial, and agricultural areas are located to analyze the behavior of pollutants conducting the scenario analysis. Considering the pollutants that affected the study area, two pollutants, oil and benzene, with different physical and chemical characteristics were selected for the analysis. As a result of comparing the actual and simulated values of the water elevation, temperature, and flow rate, it was confirmed that the model adequately reproduced the hydraulic characteristics of the Yeongsan River. The oil flow dynamics showed that an increase in flow rate led to reduction in the maximum height of the slick. Notably, the behavior of the oil was predominantly influenced by the wind conditions. In the case of benzene, lower flow scenarios exhibited decreased arrival times and residence times accompanied by an elevation in the maximum concentration levels. From the results of pollutant behavior in the study area, it is feasible to utilize the section of tributary confluence for collection and the weir area for dilution. This study enhances the understanding of the pollutant's behavior with different characteristics and develops effective control systems tailored to the physicochemical attributes of pollutants.

• Korean Journal of Agricultural and Forest Meteorology
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• v.2 no.2
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• pp.47-61
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• 2000

Agroclimatic zoning was done for paddy rice culture in North Korea based on a simulation experiment. Daily weather data for the experiment were generated by 3 steps consisting of spatial interpolation based on topoclimatological relationships, zonal summarization of grid cell values, and conversion of monthly climate data to daily weather data. Regression models for monthly climatological temperature estimation were derived from a statistical procedure using monthly averages of 51 standard weather stations in South and North Korea (1981-1994) and their spatial variables such as latitude, altitude, distance from the coast, sloping angle, and aspect-dependent field of view (openness). Selected models (0.4 to 1.6$^{\circ}C$ RMSE) were applied to the generation of monthly temperature surface over the entire North Korean territory on 1 km$\times$l km grid spacing. Monthly precipitation data were prepared by a procedure described in Yun (2000). Solar radiation data for 27 North Korean stations were reproduced by applying a relationship found in South Korea ([Solar Radiation, MJ m$^{-2}$ day$^{-1}$ ] =0.344 + 0.4756 [Extraterrestrial Solar Irradiance) + 0.0299 [Openness toward south, 0 - 255) - 1.307 [Cloud amount, 0 - 10) - 0.01 [Relative humidity, %), $r^2$=0.92, RMSE = 0.95 ). Monthly solar irradiance data of 27 points calculated from the reproduced data set were converted to 1 km$\times$1 km grid data by inverse distance weighted interpolation. The grid cell values of monthly temperature, solar radiation, and precipitation were summed up to represent corresponding county, which will serve as a land unit for the growth simulation. Finally, we randomly generated daily maximum and minimum temperature, solar irradiance and precipitation data for 30 years from the monthly climatic data for each county based on a statistical method suggested by Pickering et a1. (1994). CERES-rice, a rice growth simulation model, was tuned to accommodate agronomic characteristics of major North Korean cultivars based on observed phenological and yield data at two sites in South Korea during 1995~1998. Daily weather data were fed into the model to simulate the crop status at 183 counties in North Korea for 30 years. Results were analyzed with respect to spatial and temporal variation in yield and maturity, and used to score the suitability of the county for paddy rice culture.

• Journal of Environmental Science International
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• v.17 no.6
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• pp.623-631
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• 2008

Many recent studies have concentrated upon the radiative effects of atmospheric aerosols. Though their scattering and absorption of radiation, aerosols can also induce some other important environment effects. In this study, new radiation code and aerosol data within Atmosphere General Circulation Model (AGCM) is used to assess the aerosol radiative forcing and to analyze relative climate effects. The new Kangnung National University AGCM Stratospheric-15 (KNU AGCM ST15) was integrated by using two sets of radiative effect of aerosols: CTRL as not a radiative effect of aerosols and AERO as a radiative effect of aerosols. Two cases show the difference of net shortwave radiation budget at top-of-atmosphere (TOA) is found to be about $-3.4Wm^{-2}$, at the surface (SFC) is about $-5.6Wm^{-2}$. Consequently the mean atmospheric absorption due to aerosol layer in global is about $2.2Wm^{-2}$. This result confirms the existence of a negative forcing due to the direct effect of aerosols at the surface and TOA in global annual mean. In addition, it is found that cooling over at the surface air temperature due to radiative effect of aerosols is about $0.17^{\circ}C$. It is estimated that radiative forcing of the net upward longwave radiation taken as the indirect effect of aerosol is much smaller than that of the direct effect as there is about $0.2Wm^{-2}$ of positive forcing both at TOA and at SFC. From this study, It made an accurate estimation of considering effect of aerosols that is negative effect. This may slow the rate of projected global warming during the $21^{st}$ century.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.49 no.2
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• pp.23-30
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• 2012

This paper proposes a novel adaptive header-based power gating structure to compensate for the performance loss and the increased wake-up time of the power gating structures induced by the negative bias temperature instability (NBTI) effect. The proposed structure consists of variable width footers based on the two-pass power gating and a new NBTI sensing circuit for an adaptive control. The simulation results of the proposed structure are compared to those of power gating without the adaptive control and show that both the circuit-delay and wake-up time dependence of the power gating structure on the NBTI stress is minimized with only 3% and 4% increase, respectively while keeping small leakage power and rush-current. In this paper, a 45 nm CMOS technology and predictive NBTI model have been used to implement the proposed circuits.

• Journal of the Korean Society for Heat Treatment
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• v.31 no.6
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• pp.275-282
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• 2018

Two different modes of rolling were applied to control the texture development in tantalum sheet. In the conventional uni-directional rolling, the typical rolling textures of a body-centered cubic metal which was primarily composed of <110>//(rolling direction) was developed. In a cross rolling where the specimen was rotated by $90^{\circ}$ between each pass, the rotated cube components, i.e. {100}<011> were greatly reinforced. The prediction of lattice rotation by the full-constraint Taylor model showed that the high stability and the symmetry of the rotated cube components caused their strengthening in cross-rolling. The two specimens were heated to $1,100^{\circ}C$ at $9^{\circ}C/min$and held for 1 hour for annealing, then cooled to room temperature in atmosphere. In spite of the significant difference in the deformation textures, the annealing textures were very similar. They developed strong <111>//(plane normal) components with negligible intensity at the rotated cube components, which was attributed to the negligible capability of the latter components to provide effective recrystallized grains.

• Journal of Pharmaceutical Investigation
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• v.23 no.3
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• pp.139-144
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• 1993

Microencapsulation of acyclovir, an effective antiviral agent which acts as a specific inhibitor of herpes DNA polymerase, by carbopol-gelatin complex coacervation has been carried out to develop an oral controlled release preparation, which could improve the absorption characteristics in GI tract. After dissolving carbopol and gelatin separately in distilled water at $40^{\circ}C$, gelatin solution was mixed with carbopol solution while stirring at the same temperature. The pH of the mixture was lowered gradually by dropwise addition of 10% HCI with continuous stirring, and then, at pH 3.5, positively charged gelatin molecules were attracted to negatively charged carbopol. These coacervation processes were observed by optical microscopy during preparation. Plasma concentrations of acyclovir in rats after an oral administration of microcapsule suspension were assayed by HPLC, and pharmacokinetic parameters were calculated based on the model-independent analyses. Two standard formulations, oral solution and intravenous bolus injection, were used as references to compare the bioavailability. It has been revealed that $C_{max}$, $T_{max}$, and MRT of microcapsule suspension were greater than those of oral solution, which results in about two-fold increases in bioavailability. Therefore, in conclusion, the carbopol-gelatin microcapsule of acyclovir might be evaluated as an effective oral controlled release preparation which could increase the bioavailability of acyclovir.

• Bulletin of the Society of Naval Architects of Korea
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• v.3 no.1
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• pp.33-45
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• 1966

The effect of thermal stress on a ship's hull is not considered to be serious by most naval architects. Frequently, however, cracking of hulls has been reported which occurred at sea while there were no external forces except the heat from the sun. Detailed investigations have been made of these reports and it has been reliably determined that the damage was initiated by solar heating. The author is not interested in all steel ship or in the applicability and validity of the formular itself, as it has already been proven by the experiments such as S.S. Boulder Victory. The author therefore proceeds directly to calculate the stress distribution on he hull and superstructure of the prototype model ship. These calculations are based on the experimental nonsymetrical temperature gradient data taken earlier on the Boulder Victory. The calculations were made principally to determine the extent of stresses which occurred on an all-steel ship in one case and secondly, those that occurred on a ship with a steel hull and an aluminum superstructure. From the calculations, the author expected the stress distribution of the two case would show distinctly different aspects, but the acquired results were very similar. Generally, at the point of junction of the steel hull and aluminum superstructure sharp peak stresses appeared. At the juncture of the superstructure and the main deck the ship with the aluminum superstructure registered almost 1000 psi more stress than did the ship with the all-steel construction. In the view of these findings, the author recommends to ship designers that pay particular attention to the point of junction of steel and aluminum plate. The author has proven that it is extremely important that a greater safety factor be used at the aluminum-steel junction point than at any other point. Although thermal effects cause high juncture-point stresses in all-steel ships, they are not nearly as critical as in ship constructed of two or more metals.

• Journal of Korean Society on Water Environment
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• v.25 no.1
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• pp.7-17
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• 2009

Soil and Water Assessment Tool (SWAT) was used to assess the impact of potential future climate change on the water cycle and soil loss of the Daecheong reservoir watershed. A sensitivity analysis using influence coefficient method was conducted for two selected hydrological input parameters and three selected sediment input parameters to identify the most to the least sensitive parameters. A further detailed sensitivity analysis was performed for the parameters: Manning coefficient for channel (Cn), evaporation (ESCO), and sediment concentration in lateral (LAT_SED), support practice factor (USLA_P). Calibration and verification of SWAT were performed on monthly basis for 1993~2006 and 1977~1991, respectively. The model efficiency index (EI) and coefficient of determination ($R^2$) computed for the monthly comparisons of runoffs were 0.78 and 0.76 for the calibration period, and 0.58 and 0.65 for the verification period. The results showed that the hydrological cycle in the watershed is very sensitive to climate factors. A doubling of atmospheric $CO_2$ concentrations was predicted to result in an average annual flow increase of 27.9% and annual sediment yield increase of 23.3%. Essentially linear impacts were predicted between two precipitation change scenarios of -20, and 20%, which resulted in average annual flow and sediment yield changes at Okcheon of -53.8%, 63.0% and -55.3%, 65.8%, respectively. An average annual flow increase of 46.3% and annual sediment yield increase of 36.4% was estimated for a constant humidity increase 5%. An average annual flow decrease of 9.6% and annual sediment yield increase of 216.4% was estimated for a constant temperature increase $4^{\circ}C$.

• Transactions of the Korean hydrogen and new energy society
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• v.29 no.4
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• pp.401-409
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• 2018

A numerical investigation has been conducted to find the effects of pressure losses by struts and rakes, and averaging methods on the performance of a multi-stage axial fan and a multi-stage axial compressor. Struts and rakes which produce pressure losses are installed upstream of the aerodynamic inlet plane in the fan and the compressor rigs. Some of normal stator vanes are substituted with thick vanes with total pressure probes to measure total pressure between stages. Three-dimensional Reynolds-averaged Navier- Stokes equations with $k-{\omega}$ SST turbulence model were applied to analyze the pressure losses by the struts, inlet rakes, and thick instrumented vanes. The hexahedral grids were used to construct computational domain. Inlet pressure losses were evaluated for the compressor as a function of Mach number. The passage pressure losses due to the instrumented vanes were evaluated at the two speed lines in the fan. Total properties, such as pressure and temperature, were evaluated at the exit of the fan and the compressor with two different averaging methods which are area-averaging and mass-averaging, respectively.