• Proceedings of the Korea Water Resources Association Conference
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• 2022.05a
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• pp.320-320
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• 2022

기후변화와 도시화로 인한 영향으로 도시의 폭우, 폭염을 비롯한 현상이 빈번하게 발생하고 있다. 특히 시가화 지역의 높은 불투수율은 도시홍수를 야기한다. 이러한 현상을 완화하기 위해 도시지역에서는 그린인프라와 저영향개발이 도입되고 있다. 그 중 지속가능한 발전을 위한 필수요소로 자리매김한 옥상녹화는 도시에 위치한 건물의 상층부와 내부의 온도를 낮춤으로써 에너지절감효과와 강우 시 빗물을 저류함으로써 우수유출 저감효과, 그리고 도시 공간 내 녹지도입으로 인한 이산화탄소 배출 저감 효과 등을 기대할 수 있다. 본 연구에서는 열섬현상완화와 유출 저감의 방안 중 하나인 옥상녹화(Green roof)의 효과를 정량적으로 평가하기 위해 콘크리트로 이루어진 동일한 제원의 실험동을 구축하고, 실험동 내외부의 온도, 습도, 강우, 풍속, 일사량 등의 기상자료를 측정할 수 있는 센서를 설치하였다. 각 실험동에서 측정된 기상요소를 Flux Profile Method를 적용하여 공간 내에 있는 열에너지의 총량인 순복사열을 구성하는 현열속, 잠열속, 토양열속(H, LE, G)을 산정하였다. 또한 에너지 평형에 따라 산정된 각 실험동의 열속과 지표면 복사량 관측자료을 정량적으로 비교하여 옥상녹화의 적용성을 평가하였다. 2021년 7월 21일부터 2021년 7월 28일 까지 모니터링한 결과 옥상녹화의 열 효율은 일반 콘크리트 지붕에 비해 실내온도가 최대 6.83℃ 낮게 나타나며 이는 여름철 건물 내부의 온도조절에 필요한 에너지 저감효과를 볼 수 있다. Flux Profile Method를 적용한 결과 옥상녹화의 전체 열속 중 현열속 28.5% 잠열속 70.7%, 토양열속 0.5% 의 복사량 분포를 보였고, 일반 콘크리트 지붕은 현열속 45.3%, 잠열속 38.6%, 토양열속 16.2% 으로 나타났다. 이와 같은 방법은 옥상녹화의 정량적 평가를 가능하게 함으로서 향후 기후변화 대응방안 및 전략 수립 시 옥상녹화의 온도저감효과 분석에 적극 활용할 수 있을 것으로 판단된다.

• Proceedings of the Korea Water Resources Association Conference
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• 2021.06a
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• pp.94-94
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• 2021

현재 전 지구적으로 일어나고 있는 극단적 기후현상과 이로 인한 자연재해의 원인은 복합적이다. 기후변화로 인한 영향과 동시에 도시화 또한 하나의 원인으로 작용하고 있다. 이러한 영향을 완화하기 위한 방안으로 도시의 그린인프라와 저영향개발은 최근 지속가능한 발전을 위해 꼭 필요한 요소로 자리잡고 있다. 그린인프라 유형 중 하나인 옥상녹화는 많은 이점을 제공한다. 도시에 위치한 건물의 상층부, 내부 및 주변 온도을 낮춤으로써 얻을 수 있는 에너지절감 효과와 강우 시 상당량의 빗물을 저류함으로써 기대되는 우수유출 저감효과, 그리고 도시 공간 내 식물의 적극적인 도입으로 인한 이산화탄소 배출 저감 효과 등을 기대할 수 있다. 본 연구에서는 도시지역의 열섬현상완화와 유출저감의 방안 중 하나인 옥상녹화(Green roof)의 효과를 정량적으로 평가하기 위해 콘크리트로 이루어진 동일한 제원의 실험동을 구축하고, 실험동 내외부의 연직방향 온도, 습도, 강우, 풍속, 일사량 등의 기상자료를 측정할 수 있는 센서를 설치하였다. 각 실험동에서 측정된 기상자료를 Flux Profile Method를 적용하여 무강우기간과 강우발생기간 동안의 연직 방향의 현열속, 잠열속, 토양열속(H, LE, G) 을 산정하였다. 에너지 평형에 따라 산정된 각 실험동의 열속과 지표면 복사량 관측자료을 정량적으로 비교하여 적용성을 평가하였다. 실험의 대조군인 일반 코팅재로 마감된 콘크리트 지붕의 무강우 기간 중 최대 현열속 693.82 W/m² 잠열속은 330.15 W/m² 으로 나타났으며, 실험군인 옥상녹화가 조성된 지붕의 최대 현열속 436.27 W/m², 잠열속 949.20 W/m² 으로 나타났으며, 산정치와 관측치 시계열의 NSE는 0.81 으로 Flux Profile Method를 통해 산정된 열속의 정확도는 비교적 높은 것으로 나타났다. 이와 같은 방법으로 옥상녹화의 정량적 평가가 가능해짐으로써 향후 기후변화 대응방안 및 전략 수립 시 옥상녹화의 온도저감효과 분석에 적극 활용할 수 있을 것으로 판단된다.

• Journal of the Korean earth science society
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• v.22 no.1
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• pp.40-46
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• 2001

Heat exchange between the atmosphere and sea is produced using the data from two 3m discus buoy installed by KMA in 1996. The meteorological and oceanic characteristics at the Dukjukdo and Chilbaldo buoy for the period 1996 ${\sim}$ 2000 are discussed. Daily averaged sensible heat and latent heat flux at each site are estimated from bulk aerodynamic method using given data and analyzed. Quantitative analyses show SST indicates 1-year cycle like air temperature but has 1 month lag. Sea level pressure is lowest in July, humidity is higher from May to August, and wind speed has averaged value of 5 m/s and higher in autumn and winter. Sensible heat flux analyses present that strong heat loss from the sea occurs in autumn and winter and weak heat loss from atmosphere appears in spring and summer, and net sensible heat loss from the sea is found throughout the year. The ocean significantly releases latent heat into atmosphere from August to May but get a little latent heat from atmosphere in other months. Net latent heat loss from the sea is larger than net sensible heat loss except in January and February. Comparison with two sites suggests that the magnitude of heat flux and their fluctuation are generally stronger at Dukjukdo than at Chilbaldo. In case study, both sensible and latent heat flux is a little more at Chilbaldo in March 1998, but substantially stronger at Dukjukdo in November 1996.

• Journal of the Korean earth science society
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• v.25 no.2
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• pp.87-93
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• 2004

To study the effect of cloud on the variabilities of turbulent fluxes over the flat terrain, we used the gradient method to analyze the dynamic and thermodynamic data from the meteorological 9-m mast (0.75, 3 and 9 m) in Villafria airport in Spain. The decrease of the surface wind speed is governed by cooling at the surface following the evening transition. The sensible heat flux and the momentum flux are increased with the dynamic factor rather than the thermodynamic factor, and the sensible heat flux was not affected by the thermal condition. The global radiation did not play an important role in the variation of the sensible heat flux in the cloudy day, but the atmospheric surface layer was characterized rather by the wind intensity.

• Journal of Energy Engineering
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• v.4 no.2
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• pp.261-269
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• 1995

본 연구에서는 밀폐형 2상 열사이폰의 액체 Pool에서 발생하는 핵비등현상과 유동영역에 대해 가시화 방법으로 연구하였다. 실험용 열사이폰은 스텐레스와 유리관을 이용하여 제작하였으며, 열공급은 증발부 주위에 설치된 유도 가열용 코일에 고주파를 가함으로써 스텐레스 외면에 발열이 일어나도록 하였다. 이에 따른 결과는 다음과 같다. 실험용 열사이폰은 고주파 가열등 열사이폰의 작동성능을 저해하는 여러 요인들이 포함되어 있었으나, 실험결과 이러한 문제는 실험 내용에 영향을 미칠만큼 크게 나타나지 않았다. 열속과 상당압력의 범위는 각각2$m^2$, 0.1

• Ocean and Polar Research
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• v.27 no.3
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• pp.237-250
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• 2005

To investigate the air mass modification related with Yeongdong Heavy snowfall events, we examined sensible and latent heat fluxes on the East Sea, the energy exchange between atmosphere and ocean in this study. Sensible and latent heats were calculated by a bulk aerodynamic method, in which NCEP/NCAR reanalysis data and NOAA/AVHRR weekly SST data with high resolution were used. Among winter precipitation events in the Yeongdong region, 19 heavy precipitation events $(1995{\sim}2001)$ were selected and classified into three types (mountain, cold-coastal, and warm types). Mountain-type precipitation shows highly positive anomalies of sensible and latent heats over the southwestern part of the East Set When separating them into the two components due to variability of wind and temperature/ specific Humidity, it is shown that the wind components are dominant. Cold-coastal-type precipitation also shows strong positive anomalies of sensible and latent heats over the northern part and over the central-northern part of the East Sea, respectively. It is shown that the sensible heat anomalies are caused mostly by the decrease of surface air temperature. So it can be explained that cold-coastal-type precipitation is closely related with the air mass modification due to cold air advection over warm ocean surface. But in warm-type precipitation, negative anomalies are found in the sensible and latent heat distributions. From this result, it may be postulated that warm-type precipitation is affected by the internal process of the atmosphere rather than the atmosphere-ocean interaction.

• Atmosphere
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• v.25 no.2
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• pp.193-203
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• 2015

A large aperture scintillometer (LAS) was deployed with an optical path length of 2.1 km to estimate turbulent sensible heat flux (${\mathcal{Q}}_H$) over a highly heterogeneous urban area. Scintillation measurements were conducted during cold season in November and December 2013, and the daytime data of 14 days were used in the analysis after quality control processes. The LAS-derived ${\mathcal{Q}}_H$ show reasonable temporal variation ranging $20{\sim}160W\;m^{-2}$ in unstable atmospheric conditions, and well compare with the measured net radiation. The LAS footprint analysis suggests that ${\mathcal{Q}}_H$ can be relatively high when the newly built-up urban area has high source contribution of the turbulent flux in the study area ('northwesterly winds'). Sensitivity tests show that the LAS-derived ${\mathcal{Q}}_H$ are highly sensitive to non-dimensional similarity function for temperature structure function parameter, but relatively less sensitive to surface aerodynamic parameters and meteorological variables (temperature and wind speed). A lower Bowen ratio also has a significant influence on the flux estimation. Overall uncertainty of the estimated daytime ${\mathcal{Q}}_H$ is expected within about 20% at an upper limit for the analysis data. It is also found that stable atmospheric conditions can be poorly determined when the scintillometry technique is applied over the highly heterogeneous urban area.

• Journal of the Korean earth science society
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• v.26 no.5
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• pp.395-403
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• 2005

This study is focused on the relationship between snowfall and the Bowen’s Ratio (sensible heat flux/latent heat flux) through calculation of heat exchange between air and sea for snowfall events in Jeju Island from 1993 to 2003. The four weather stations for this study are located at Jeju, Seoguipo, Seongsanpo and Gosan in Jeju Island. In order to improve the reliability of snowfall forecast, the Bowen’s Ratio for snowfall, which includes influences from the atmosphere such as wind, is compared with the temperature difference between air and sea for snowfall. As a results, in the case for fresh snowfall, the minimum temperature differences between air and sea were 10, 12.3, 11.5, and $14.3^{\circ}C$ at Jeju, Seoguipo, Seongsanpo and Gosan, respectively. The probabilities of fresh snowfall were 26, 29, 13, and $23\%$, respectively, when the temperature differences were higher than the previous values. On the other hand, the minimum Bowen ratios were 0.59, 0.60, 0.65 and 0.65 at Jeju, Seoguipo, Seongsanpo and Gosan, respectively. The probabilities of fresh snowfall were 33, 70, 31 and $58\%$ respectively, when the Bowen ratio is higher than those. The reason for this is because the probability of fresh snowfall with the Bowen ratio was higher than the probability with temperature difference between air and sea. This result occurred because heat exchange by wind increased the probability of snowfall, along with the temperature difference between air and sea, and the Bowen ratio. Therefore, snowfall forecast of Jeju Island is significantly influenced by the sea, whereas forecast with Bowen ratio seems to have higher reliability than that with the temperature difference between air and sea. The data analysis for the ten-year period $(1993\~2002)$ showed that when each fresh snowfall was within 0.0 to 0.9cm, the average Bowen’s ratio was 0.63 to 0.67, and when each fresh snowfall was 1.0 to 4.9 cm, the average Bowen’s ratio was over 0.72. Therefore, fresh snowfall shows a proportional relationship with the Bowen’s ratio during snowfall.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.3 no.1
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• pp.9-15
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• 1998

Hourly meteorological data from a marine buoy ($34^{\circ}49'00"N$, $125^{\circ}46'00"E$) operated by the Korean Meteorological Agency were obtained from July, 1996 to February, 1997. From the data air-sea heat fluxes and marine meteorological characteristics around the area are estimated. The maximum outflux of sensible heat from the sea surface occurred in January (monthly mean value, 12.6 $Wm^{-2}$ and the maximum influx to the sea occurred in July (monthly mean value, 5.5 $Wm^{-2}$). This means that the sea is heated in summer while it loses its heat in winter, and that there is inequality between the absolute values of the two seasons. The outflux of the maximum latent heat occurred in November (monthly mean value, 86.5 $Wm^{-2}$) and reach a value of 300 $Wm^{-2}$, and the maximum influx occurred in July (monthly mean value, 4.6 $Wm^{-2}$). Big difference is shown in their absolute values when the wind becomes strong. The outgoing latent heat flux reaches its maximum in autumn, and it maintains the high value through the whole winter. According to the wave data analysis, the significant wave heights are larger in winter than in summer. The periods of the significant waves are 4~6 sec. In winter, waves propagated from north and northeast are dominant because of the winter monsoon, while in summer waves from south, southwest, and west are relatively frequent.

• Journal of the Korean Society of Marine Environment & Safety
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• v.12 no.1 s.24
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• pp.23-32
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• 2006

This study was conducted to find out the effects of meterological factors on oceanic conditions when cold and dry continental air mass passes through the western sea of Korea The change of ocean conditions during the winter season were more obvious in coastal area than open sea And sea surface temperature (SST) during February is lower by $3^{\circ}C$ than December but in coastal area SST dropped by $3^{\circ}C$. As for the salinity, there was not much difference between areas except southern area of Mokpo. In the coastal regions, air temperature(AT) and SST showed a positive correlation; as the air temperature goes up with the increase of SST and when the former goes down the latter decrease. SST of open sea seems to be changed by latent (Qe) and sensible heat (Qs), when the open sea lose its heat by Qe and Qs then SST goes down And when they get the heat then the SST goes up. 1here was a positive correlation between the AT of the coastal region and sea surface salinity (SSS), when the AT goes up then SSS increase and when the former goes down the latter decrease. Precipitation during the summer seasons (June$\sim$September) appeared to the more closely related with salinity of February of the following year than those of October and December.