• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2014.10a
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• pp.800-811
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• 2014

Recent developments in the prediction of the contribution of windnoise to the interior SPL have opened a realm of new possibilities in terms of i) how the convective and acoustic sources terms can be identified, ii) how the interaction between the source terms and the side glass can be described and finally iii) how the transfer path from the sources to the interior of the vehicle can be modelled. This work discusses in details these three aspects of wind noise simulation and recommends appropriate methods to deliver required results at the right time based on i) simulation and experimental data availability, ii) design stage at which a decision must be made and iii) time available to deliver these results. Several simulation methods are used to represent the physical phenomena involved such as CFD, FEM, BEM, FE/SEA Coupled and SEA. Furthermore, a 1D and 2D wavenumber transformation is used to extract key parameters such as the convective and the acoustic component of the turbulent flow from CFD and/or experimental data whenever available. This work focuses on the validation of the wind noise source characterization method and the vibro-acoustic models on which the wind noise sources are applied.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2014.10a
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• pp.563-564
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• 2014

Recent developments in the prediction of the contribution of windnoise to the interior SPL have opened a realm of new possibilities in terms of i) how the convective and acoustic sources terms can be identified, ii) how the interaction between the source terms and the side glass can be described and finally iii) how the transfer path from the sources to the interior of the vehicle can be modelled. This work discusses several simulation methods that can be used to represent the physical phenomena involved such as CFD, FEM, BEM, FE/SEA Coupled and SEA. This work focuses on the validation of the wind noise source characterization method and the vibro-acoustic models on which the wind noise sources are applied in the framework of a benchmark proposed by Hyundai Motors Corporation.

• Journal of the Korean Association of Geographic Information Studies
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• v.27 no.1
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• pp.12-28
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• 2024

This study aims to identify the trend of changes in tourist floating population before and after COVID-19 in major tourist destinations in Jeju Island through spatial analysis. Seongsan-eup and Andeok-myeon in Jeju Island were selected as the research area, and the research period was set at 1 year before and 2 years after the COVID-19 outbreak. For the analysis, mobile floating population data was refined and processed to calculate floating population distribution and floating population increase/decrease data. This was converted into spatial data and an overlay analysis was performed with location data of major tourist attractions. As a result of the analysis, it was confirmed that the floating population of indoor tourist attractions and small facilities decreased immediately after COVID-19, and that in open coastal areas or large facilities, the floating population decreased less or actually increased. In conclusion, in tourism development, it is necessary to identify changes in floating population according to the characteristics of tourist facilities, and it is necessary to develop tourism facilities and strategies that can respond to risk situations such as pandemics when developing tourist destinations.

• Proceedings of the Korean Institute of Industrial Safety Conference
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• 2000.06a
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• pp.186-189
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• 2000

국내의 건축물의 화재안전성 평가는 화재안전성을 고려한 공간구성, 연기의 유동, 거주자의 피난계획 및 피난성능평가, 건축물 내부에 설치된 방화설비계통의 화재안전성능평가 등을 연구하여 왔다. 그런데 이들 연구의 대부분은 건축물의 공간적 특성분석과 주거여건 등을 고려한 기초자료의 파악 및 분석 등을 국내의 여건과는 상이한 국외의 자료를 근거로 하거나 2차원적인 해석 및 평가에 그치고 있는 경향이 있다. (중략)

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2001.09a
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• pp.239-243
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• 2001

대수층에서 오염물질의 이동은 대류, 확산, 흡착 등의 물리화학적 현상에 영향을 받는다. 지하수 유동과 오염 물질 운송에 관련된 분석은 지하수 자원의 관리와 평가, 복원사업에 필요한 요소이다. 본 연구의 목적은 사질대수층에서의 2차원 plume 모니터링을 통하여 오염운의 관측치와 모사치를 비교하므로써 종분산지수와 종/횡분산지수비를 결정하는 것이다. 실내 자유면 대수층 실험에서 MT3D를 이용한 case study로부터 추정된 종분산지수는 0.4 cm였으며 횡/종분산지수비는 1/5로 나타났다.

• Proceedings of the Korea Air Pollution Research Association Conference
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• 2000.11a
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• pp.130-131
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• 2000

라돈(Rn-222)은 우라늄(U-238) 방사능계열의 원소로서 라듐(Ra-226)의 붕괴시 자연생성되는 가스상 물질이다. 화학적으로는 불활성이며 무색, 무취의 특성을 가지고 있다. 공기보다 8∼9배 무겁기 때문에 지표면 가깝게 존재하므로 인체노출이 쉬운 물질로 알려져 있다. 라돈은 최근까지도 온천 등지에서 건강에 매우 좋은 원소로 알려져 왔으나 사실은 기준치 이상의 라돈을 마시거나 호흡했을 경우, 치명적인 폐암을 유발시킨다는 것이 밝혀졌다(Doull et al, 1999) (중략)

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 2002.07a
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• pp.249-254
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• 2002

온실에서 환기는 외기와의 공기교환을 통한 온도 및 습도의 조절뿐만 아니라 이산화탄소 등의 가스농도를 조절함으로써 온실내 공기의 쾌적성 확보와 실내기류의 형성으로 인한 작물의 생육촉진에도 중요한 역할을 담당한다. 그러므로, 작물생육환경의 최적화를 통한 품질향상 및 수확량 증대를 목적으로 하는 온실재배에 있어서 환기특성 분석 및 공기유동 예측은 가장 기본적인 설계요소라 할 수 있다. (중략)

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.9 no.1
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• pp.43-55
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• 1997

Existing theories and experimental results on mud bed consolidation, fluidization and erosion are briefly reviewed. The importance of the history of bed shear strength profile which experiences periodic and random consolidation and fluidization is qualitatively discussed by reanalyzing a field data set in Youngkwang area of Korea. According to the results of existing laboratory experiments and the reanalyzing, the numerical modelling of mud or pollutant transport without considering consolidation and fluidization may cause the time lag between the hydrodynamic forcing and the increment of sediment and bed-originated pollutant concentrations in water column. The time lag can derive serious error in the transport direction, consequently in the budget of a heavy-concentrated bottom-originated substance, especially in macrotidal environments with relatively high wave energy.

• Journal of the Korean Geotechnical Society
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• v.34 no.11
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• pp.33-41
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• 2018

Soil internal erosion is a phenomenon in which fines attached to the solid skeleton are detached by fluid flow, and this continuous fine migration weakens the hydro-mechanical characteristics of the ground structure. This paper proposed governing equations for fine migration in pore spaces and its related scheme for the numerical analysis. Phase diagram for fine particles includes three different states: detached fines in the liquid phase ($c_e$), attached fines in the solid phase (${\sigma}_a$), and pore-clogged fines in the solid phase (${\sigma}_s$). Numerical formulations for finite element method are developed based on the hydraulic governing equations of pore fluid and fine migration. This study proposed a method of estimating model parameters for fine detachment, attachment, and clogging from 1D erosion experiments. And it proposed an analytical formula for hydraulic permeability function considering fine clogging. Numerical analysis of the previous erosion test developed the numerical scheme and verified the adequacy of fine migration models.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.29 no.5C
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• pp.229-237
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• 2009

A conventional way of backfilling has used sand or in-situ soil. It not only requires substantial amount of time and cost but also makes it particularly difficult to fill the bottom part and small cracks of a pipe. To address the problem with the conventional method of compaction, liquefied stabilized soil was proposed as an alternative because it reuses in-situ soil which can ensure sand supply while adjusting flowability and strength of the soil with design of mix proportion. With an aim to identify the mixing properties of liquefied stabilized soil depending on the organic content of in-situ soil, this study conducted indoor tests of material segregation, flowability, strength, and permeability by changing humic acid content of the soil. The results revealed that material segregation and flowability increased proportionally while strength decreased with the increased amount of humic acid. In the mean time, permeability of liquefied stabilized soil wasn't affected by organic content.