• 한국대기환경학회지
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• 제18권4호
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• pp.275-284
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• 2002

Atmospheric concentrations of organochlorine pesticides (OCPs) in Seoul, South Korea between July 1999 and May 2000 were determined to investigate concentration distribution in air, relationship between concentrations and meteorological conditions, and apportionment of sources e.g. local sources (air- surface exchange) and long range transport. Endosulfan and $\alpha$-HCH were the highest concentrations in atmosphere with values typcally ranging from 10s to l00s of pg/㎥. These high concentrations may be attributed to their usage, period and chemical property (Koa). All OCPs also showed elevated levels during the summer and were positively correlated with temperature. This would suggest that a seasonal enhancement was due to (re)volatilization from secondary sources and application during the warmer months. The temperature dependence of atmospheric concentrations of OCPs were investigated using plots of the natural logarithm of partial pressure (In P) vs reciprocal mean temperatures (1/T), and environmental phase-transition energies were calculated for each of the pesticides. For OCPs, temperature dependence was statistically significant (at the 99.99% confidence level) and temperature accounted for 35~95% of the variability in concentrations. The relatively higher slopes and phase-transition energies for $\alpha$-, ${\gamma}$-chlordane, endosulfan and endosulfan sulfate suggested that volatilization from local sources influenced their concentrations. The relatively lower those for $\alpha$-, ${\gamma}$-HCH, p, p'-DDE and heptachlor epoxide also suggested that volatilization from local sources and long range transport influenced their concentrations.

• 한국농림기상학회지
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• 제6권4호
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• pp.272-289
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• 2004

The spatial resolution of local weather and climate information for agronomic practices exceeds the current weather service scale. To supplement the insufficient spatial resolution of official forecasts and observations, gridded climate data are frequently generated. Most ecological models can be run using gridded climate data to produce ecosystem responses at landscape scales. In this lecture, state of the art techniques derived from geospatial climatology, which can generate gridded climate data by spatially interpolating point observations at synoptic weather stations, will be introduced. Removal of the urban effects embedded in the interpolated surfaces of daily minimum temperature, incorporation of local geographic potential for cold air accumulation into the minimum temperature interpolation scheme, and solar irradiance correction for daytime hourly temperature estimation are presented. Some experiences obtained from their application to real landscapes will be described.

• 설비공학논문집
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• 제12권10호
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• pp.886-893
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• 2000

A good understanding of the heat transfer distribution is very important to suppress the deformation of steel products. In this study, the local heat transfer coefficients are experimentally investigated to understand the heat transfer distribution of thick steel plates with even flat spray nozzle. The steel slabs are cooled down from the initial temperature of about $1000^{\circ}C$ , and the local heat transfer coefficients and surface temperatures are calculated from the measured temperature-time history. The results show that the local heat transfer coefficients of spray cooling are dominated by the local droplet flow rate, and in proportion to becoming more distant from the center of heat transfer surface, the local heat transfer coefficients decrease with the decrease of the local droplet flow rate.

• Journal of Advanced Marine Engineering and Technology
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• 제24권3호
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• pp.13-19
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• 2000

In the present study, a program for predicting thermal performance of an air cooled condenser is illustrated. Heat transfer equations of single phase and two phase flow are formulated into the form that is convenient to incorporate the local analysis method. The resulting equations are solved by temperature and mass correction methods. Empirical equations for both side fluids are incorporated in the caculation procedures. In order to compare the calculation results, superheat temperature of steam are varied. The tube length of superheated zone, wall temperature, temperature profile along the tube and steam qualities are predicted.

• 한국해안·해양공학회논문집
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• 제20권1호
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• pp.34-41
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• 2008

미래 연안 생태환경변화 예측을 위한 기후변화에 따른 수온변화 예측이 필요하며, 연안 수온변화는 GCM 자료에서 제공하는 미래 기온변화 예측자료를 국지적인 기온자료로 Downscaling 기법을 적용하여 사용할 수 있다. 본 연구에서는 선형회귀분석기법을 이용하여 2000년${\sim}$2005년 우리나라 평균기온자료를 연안해역의 국지적인 기온자료로 Downscaling 하는 방법을 제안하고, 제안한 방법의 검증을 수행하였다. Downscaling 방법의 보정과정에서의 RMS오차 평균은 1.584정도이며, 2006년${\sim}$2007년 자료를 이용한 검정과정에서의 RMS 오차 평균은 1.675, 1.448 정도로 추정오차는 보정과정에서의 오차수준을 유지하고 있는 것으로 파악되었다. 또한, NSC 값도 보정과정에서는 0.962, 2006년${\sim}$2007년 자료를 이용한 검정과정에서는 0.955, 0.963으로 보정과정에서의 일치수준을 유지하고 있는 것으로 파악되어 선형회귀분석 기법을 이용한 우리나라 연안의 국지적인 기온은 RMS 오차 $1.0{\sim}2.0^{\circ}C$ 수준으로 전국 평균기온을 이용하여 추정할 수 있다.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2009년도 하계학술발표대회 논문집
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• pp.804-809
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• 2009

The present study measured frost pattern on a cylinder to propose empirical correlation equations for the local and average frost thickness, frost density and frost mass. The key parameters were diameter of the cylinders (7mm, 20mm), cooling surface temperature of the circular tube, absolute humidity of air, air temperature and air velocity. A 50% ethylene glycol aqueous solution was applied as a coolant. The frost thicknesses at both front and rear were larger than those at the other parts, while they were increased as diameter of the cylinder was increased. The local frost thicknesses at high air velocity were more uniform than those at low air velocity. The values predicted by Kim et al. under the freezer condition showed larger by the maximum of $30{\sim}50%$ than the measured data under heat pump condition. The empirical correlations for the local and average frost thickness and frost mass were proposed. The correlation equations for the frost thickness and frost mass under the heat pump condition in the present study might predict more accurate than the other correlation equations. The proposed correlations might be applied for the freezer condition within the maximum 15% deviation from the previous correlations under freezer condition.

• 대기
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• 제26권3호
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• pp.445-459
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• 2016

Air temperature deviation (ATD) is one of major indicators to represent spatial distribution of urban heat island (UHI), which is induced from the urbanization. The purpose of this study is to evaluate the accuracy of air temperature deviation about Climate Analysis Seoul (CAS) workbench, which had developed by National Institute Meteorological Science and TU Berlin. Comparison and correlation analysis for CAS ATD including meso-scale air temperature deviation, local-scale air temperature deviation, total air temperature deviation, surface heat flux deviation, cold air production deviation among meso-scale numerical modelling variable in 'Seoul Region', micro-scale numerical modelling in 'Detail Region', and CAS workbench variable using observation data in ground stations. Comparison between night time OBS ATD and CAS ATD show that have most close values. Most of observations ($dT_{max}$ and $dT_{min}$) have highly positive ($dT_{SHP}$, $dT_{CA}$, MD, TD, $f_{BS}$, $f_{US}$, $f_{WS}$, $h_B$) and negative ($f_{VS}$, $f_{TV}$, $h_V$, Z) correlations. However, CAS workbench needs further improvement of both observational framework and analytical framework to resolve the problems; (1) night time OBS ATD of has closer values in compare with at high rise mountain area and (2) correlations are very dependable to meteorological scale.

• KIEAE Journal
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• 제14권4호
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• pp.127-131
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• 2014

The ground source heat pump (GSHP) system is a kind of the temperature differential energy system using relatively stable underground temperature as heat source of space heating and cooling. This system can achieve higher performance of system than it of conventional air source heat pump systems. However, its superiority of the system performance is different according to installation location or local climate, because the system performance depends on the underground condition which is decided by annual average air temperature. In this study, in order to estimate the feasibility of the ground source heat pump system according to the local climate, numerical simulation was conducted using the ground heat transfer model and the surface heat balance model. The case study was conducted in the condition of Seoul, Daejeon, and Busan, In the result, the heat exchange rate of Busan was 34.33 W/m as the largest in heating season and it of Seoul was 40.61 W/m as the largest in cooling.

• 설비공학논문집
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• 제10권5호
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• pp.523-534
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• 1998

The convection heat transfer on horizontal circular tube is studied as a conjugated heat transfer problem. With uniform heat generation in a cylindrical heater placed in a cross flow boundary condition, heat flow that is conducted along the wall of the heater creates a non-isothermal surface temperature and non-uniform heat flux distribution. In the present investigation, the effects of circumferential wall heat conduction on convection heat transfer are investigated for the case of forced convection around horizontal circular tube in cross flow of air and water. Non-dimensional conjugation parameter $ K^*$ which can be deduced from the governing energy differential equation should be used to express the effect of circumferential wall heat conduction. Two-dimensional temperature distribution$ T({\gamma,\theta})$ is presented. The influence of circumferential wall heat conduction is demonstrated on graph of local Nusselt number.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 춘계학술대회
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• pp.1546-1551
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• 2004

This paper presents a mathematical model to predict the frost properties and heal and mass transfer within the frost layer formed on a cold plate. The laminar flow equations for the air-side are analyzed. and the empirical correlations of local frost properties are employed in order to predict the frost layer growth. The correlations of local frost density and effective thermal conductivity of frost layer, obtained from various experimental conditions, are derived as functions of various frosting parameters (Reynolds number, frost surface temperature, absolute humidity and temperature of moist air, cooling plate temperature, and frost density). The numerical results are compared with experimental data and the results of various models to validate the present model, and agree well with experimental data within a maximum error of 10%. The heat and mass transfer coefficients obtained from the numerical analyses are presented, as the results, it is found that the model for frost growth using the correlation of heat transfer coefficient without solving air flow have a limitation in its application.