• The Journal of the Korea institute of electronic communication sciences
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• v.16 no.3
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• pp.429-436
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• 2021

The wind profilers operated by the Korea Meteorological Administration observe in a low mode for intensive observation of the low levels and a high mode for intensive observation of the high levels. The LAP-3000 wind profiler installed in Bukgangneung and Changwon is characterized by the same sampling frequency of the low mode and the high mode, allowing to compare winds observed in both modes at the same altitude. As a result of analyzing the wind speed of the two points for one year in 2020, the correlation between the two modes was up to 0.2 lower than the correlation with radiosonde. The T-test for the wind speed of the two modes showed a particularly significant difference in October, where the temperature and specific humidity fluctuate frequently. The difference in the development of the atmospheric boundary layer affects the accuracy of the wind speed depending on the observation mode.

• Proceedings of the Korean Society of Coastal and Ocean Engineers Conference
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• 1996.10a
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• pp.29-33
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• 1996

태풍이 불 때 대기경계층과 해파사이에는 수면의 $C_{D}$ 가 증가하는데 이는 해파만이 아니라 강한 해조류와 해일의 영향을 받게 된다. 따라서 이러한 현상이 파랑이 발달과정에 영향을 주게됨으로 기상외력에 따른 이 과정을 복합한 해파, 조석, 해일모형으로서 접근하는 것이 타당한 방법이다. 현실적으로는 광역의 태풍해파의 모형에 있어서 방대한 자료와 컴퓨터능력을 필요로 하기 때문에 이러한 수치실험은 극히 제한적으로만 이루어졌다(Wu와 Flather, 1992). (중략)

• Journal of the Korean earth science society
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• v.31 no.7
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• pp.738-748
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• 2010

In order to clarify the impact of variation of albedo on the atmospheric boundary layer caused by the density of building in urban areas, both satellite data analysis and numerical experiments were carried out. Utilized satellite data were multi-spectral visible data detected by the Korea Multi- Purpose Satellite -2 (KOMSAT-2), and the numerical models for the estimation of surface heat budget are Albedo Calculation Model (ACM) and Oregon State University Planetary Boundary Layer model (OSUPBL). In satellite data analysis, the estimated albedo in densely populated building area is lower than other regions by 17% at the maximum due to the shadow effect of skyscraper buildings. The surface temperature reached $43.5^{\circ}C$ in the highly dense and tall building area and $37.4^{\circ}C$ in the coarse density area of low buildings, respectively. However, the low albedo in densely integrated building area is not directly related to the increase of surface air temperature since the mechanical turbulence induced by the roughness of buildings is more critical in its impact than the decrease of albedo.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.25 no.12
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• pp.1821-1830
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• 2001

The flow around free end of a finite circular cylinder (FC) embedded in an atmospheric boundary layer has been investigated experimentally. The experiments were carried out in a closed-return type subsonic wind tunnel with varying aspect ratio of the finite cylinder mounted vertically on a flat plate. The wakes behind a 2-D cylinder and a finite cylinder located in a uniform flow were measured for comparison. Reynolds number based on the cylinder diameter was about Re=20,000. A hot-wire anemometer was employed to measure the wake velocity and the mean pressure distributions on the cylinder surface were also measured. The flow past the FC free end shows a complicated three-dimensional wake structure and flow phenomenon is quite different from that of 2-D cylinder. The three-dimensional flow structure was attributed to the downwashing counter rotating vortices separated from the FC free end. As the FC aspect ratio decreases, the vortex shedding frequency decreases and the vortex formation length increases compared to that of 2-D cylinder. Due to the descending counter-rotating twin-vortex, near the FC free end, regular vortex shedding from the cylinder is suppressed and the vortex formation region is hardly distinguished. Around the center of the wake, the mean velocity for the FC located in atmospheric boundary layer has large velocity deficit compared to that of uniform flow.

• Journal of Ocean Engineering and Technology
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• v.3 no.2
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• pp.35-44
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• 1989

남극의 설퇴현상을 모의실험하기 위하여 폐쇠식 대기경계층난류풍동을 호주 시드니대학토목공학과에 제작 설치하였다. 철강과 100mm높이의 구형판자 및 촘촘한 양탄자등의 실험요소를 사용하여 경계층전단난류를 유도발생켰다. 유도발생된 난류는 호주령 남극령토의 해안지역에 부는 난류와 비슷한 유형을 뛰었다. 자연눈에 대처할 물질을 찾기 위하여 몇몇종류의 가루를 사용하였으나 중탄산나트륨이 가장 적합한 것임이 증명되었다. 남극건물모델주위에 실험을 통해 쌓인 눈의 형태로부터 등고선무늬를 형상화 시켰으며 image processing unit을 이용하여 등고선무늬를 포착한 후 등고선 분석 software를 이용, 눈의 형태와 양을 분석하였다.

• The Korean Journal of Petroleum Geology
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• v.9 no.1_2 s.10
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• pp.1-15
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• 2001

Hierarchically controlled sequence stratigraphic analysis shows that the Lower Ordovician mixed carbonatesiliciclastic Mungok Formation, Korea consists of three depositional sequences: T1, T2, and T3 in ascending order. Sequence boundaries are generally marked by abrupt transition from coarse-grained shallow-water carbonates to finegrained deeper-water carbonates mixed with fine-grained siliciclastics, and show indication of subaerial exposure such as karstification. Within this sequence stratigraphic framework, facies characteristics indicate that the Mungok sequences were mostly deposited on a subtidal ramp without slope break. The Mungok ramp had been under the influence of frequent tropical storm activity during deposition. The difference in lithology of tempestites seems to have been controlled by the nature of substrates and by proximality. High-frequency cycles consist of upward-shallowing facies successions. Cycles of shallow-water and basinal deposits are not well represented, probably due to cycle amalgamation. Cycle stacking patterns do not show a consistent thickness change that is usually associated with a large-scale sea-level change probably because of unfilled accommodation space.

• Journal of Korean Society for Atmospheric Environment
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• v.21 no.5
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• pp.537-545
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• 2005

A new dispersion model for dense gas is constructed in the Lagrangian framework. Prediction of concentration by the proposed model is compared with measure data obtained in the experiment conducted in Thorney Island in 1984. Two major effects of dense gas dispersion, gravity slumping and stratification effect, are successfully incorporated into LDM (Lagrangian dense gas model). Entrainment effect is naturally modelled by introducing stochastic dispersion model with the effect of turbulence suppression by stratification. Not only various releasing conditions but also complex terrain can be extended to, although proposed model is appropriate for flat terrain.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.20 no.8
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• pp.2670-2680
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• 1996

Effeccs of porous wind fence on surface-pressure around 2-dimensional prism model of triangular cross-section were investigated experimentally. The pressure data were obtained at a Reynolds number based on the model height of Re=2.1*10$^{5}$ . Flow visualization also carried out to investigate the flow structure qualitatively. The mean velocity and turbulent intensity profiles measured at fence location were well fitted to the neutral atmospheric surface boundary layer over the open terrain. Various fences with different porosity and height were tested to investigate their effects on the surface pressure acting on a prism model at different locations. As the results, porous fence with porosity 40 ~ 50% is most effective for abating wind erosion. With decreasing porosity of the fence, pressure fluctuations on the model surface are increased. The mean pressure coefficients are decreased only when the fence height is greater than the model height. The effect of distance between wind fence and triangular prism was not significant, compared to that of the fence porosity and height.

• Journal of the Korea Concrete Institute
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• v.14 no.5
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• pp.766-773
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• 2002

The failure phenomenon of overlaid concrete structures, such as surface crack, and peel-off failure, shear bond failure in the end contact zone, was investigated due to humidity changes. To investigate this failure phenomenon, the surface tensile stress, and the shear stress, the vertical tensile stress in the contact zone were analysed using the non-linear stress-strain relationship of material such as strain-hardening- and strain-softening diagrams. Overlay thickness and overlay material were the main variables in the analyses. It is assumed that the initial surface humidity of overlaid concrete structures was 100％ r.H. With a atmospheric humidity of 55％ r.H. and two load cases for drying(LCI), curing and drying(LC2), the stress states of overlaid concrete structures were calculated. The result shows that only fictitious cracks occurred in the overlay surface of CM2O, ECM25, and no shear bond failure occurred in the contact zone without CM2O. The peel-off failure was proved to be the main cause of the damage in the overlaid concrete structures. Only for overlay thickness of 1cm occurred no peel-off failure in the case of drying after a long-term public use(LC1). In the case of curing and drying during overlay work(LC2) occurred the peel-off failure within 1.5days for all the overlaid concrete structures.

• Atmosphere
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• v.20 no.3
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• pp.319-332
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• 2010

Sensitivity experiments of WRF model using different planetary boundary layer (PBL) and land surface model (LSM) parameterizations are evaluated for prediction of wind fields within the surface layer. The experiments were performed with three PBL schemes (YSU, Pleim, MYJ) in combination with three land surface models (Noah, RUC, Pleim). The WRF model was conducted on a nested grid from 27-km to 1-km horizontal resolution. The simulations validated wind speed and direction at 10 m and 80 m above ground level at a 1-km spatial resolution over the South Korea. Statistical verification results indicate that Pleim and YSU PBL schemes are in good agreement with observations at 10 m above ground level, while the MYJ scheme produced predictions similar to the observed wind speed at 80 m above ground level. LSM comparisons indicate that the RUC model performs best in predicting 10-m and 80-m wind speed. It is found that MYJ (PBL) - RUC (LSM) simulations yielded the best results for wind field in the surface layer. The choice of PBL and LSM parameterization will contribute to more accurate wind predictions for air quality studies and wind power using WRF.