SWAN Nested model의 현장 적용성 분석

김강민(Kang-Min Kim),남기대(Nam-Ki Dae),이중우(Joong-woo Lee) 한국항해항만학회 2011 한국항해항만학회지 Vol.35 No.1

최근 추세에 따라 수치실험은 높은 해상도와 정확도를 요구하고 있다. 일반적으로 파랑장 계산은 광역모형을 도입하고, 주된 해석 대상 영역의 지형적 복잡성을 반영할 수 있는 적절한 분해능의 상세격자를 통해 내부의 상세역 모형을 구성하게 된다. 여기서, 세역에서의 입사파는 광역에서의 결과를 토대로 추출하게 되는데, 이 때 결과의 연속성에서 문제를 가지게 된다. 대체로 이러한 문제점을 극복하기 위하여 가변격자체계와 스펙트럼 추출 등의 방법을 사용하게 되지만 관련 수치적 오류에 대한 분석과 검토가 충분하지 않은 것으로 보인다. 따라서, 본 연구에서는 최근 가장 일반적으로 사용되고 있는 SWAN모형의 Nested 모형에 대한 현장 적용성을 확인하고자 한다. 이를 위하여 각기 다른 조석환경하에 있는 두 개의 항에 대한 실험을 실시하고 이에 대한 결과를 비교･분석하였다. 분석결과, Nested 모형으로 구성된 광역과 세역 경계에서의 추출된 값이 거의 동일한 값을 가지며 각기 다른 조석환경하에서의 결과 또한 다르지 않다는 것으로 나타났다. 그러나, Nested 모형의 경계를 구성시 수심의 변화가 심한 곳을 피하고 비교적 수심이 깊은 해역까지를 포함시키는 것이 오차를 줄일 수 있음을 확인하였다. The recent trend for numerical experiment requires more higher resolution and accuracy. Generally, in the wave field calculation, it starts with a large region formulation first and follows by a separated detailed region formulation by more denser grids for the main interest area considering the geographical and bathymetrical variation. The wave fields resulted from the large region calculation is being introduced into the detail region calculation as the incident waves. In this process there exists a problem of continuity. In order to get over such problem, method of variable gridding system or spectrum sampling, etc., is being used. However, it seems not enough to examine and analyze the related numerical errors. Therefore, it is investigated in this study the field applicability of the most pervasive use of wave model, the nested SWAN model. For this purpose, we made model experiment for two coastal harbours with different tidal environment, and compared and analyzed the result. From the analysis, it was found that both the extracted values, near the boundaries of the large and detail region and the nested formulation of SWAN model, show almost the same and no different between those with different tidal environment conditions. However it is necessary for reducing the numerical errors to set the boundaries for the detailed region outside of the rapid bathymetric change and deeper region.

CFD모델과 풍동실험을 이용한 복잡지형에서의 기류해석

문기영,김석철,신구용,조경학,윤정임,황규석,길용식 한국풍공학회 2009 한국풍공학회지 Vol.13 No.3

Winds over a complex terrain were analyzed using wind tunnel and several computational fluid dynamics (CFD) models. A mountain area adjacent to a shoreline was chosen in a Southern Korea Peninsula for study. Two different CFD models were used for simulating flows: one is an FVM code with Virtual Boundary Method(VBM) using LES for sub-grid turbulence, and the other is a commercial package implemented with 4 different RANS (Reynolds Averaged Navier-Stokes Equations) turbulence models. The CFD simulations were compared with wind tunnel data at several locations where wind speeds were greatly enhanced or reduced due to the surrounding topographic features. The agreement between the CFD simulations and the wind tunnel experiments were good, the correlation coefficients ranging 0.890 ~ 0.965. The FVM code was excellent of which correlation coefficient was 0.965. 자연지형에 의한 기류 변화를 CFD 모델과 풍동실험을 통하여 비교 연구하였다. 해안에 인접한 남부 산악지형을 대상으로 풍동실험과 몇 종류의 CFD 모델 시뮬레이션을 수행하였다. 사용한 CFD 모델은 2 가지로, 하나는 LES 난류모델을 사용하는 가상경계기법을 활용한 유한체적법(Finite Volume Method, FVM) 코드와 또 하나는 4 가지 RANS 난류모델이 선택사양으로 제공되는 상업용 CFD 모델이다. 지형에 의해 풍속이 증가되는 지점과 감소되는 지점에서 수직풍속분포를 직접 비교하고 상관도를 구하였다. CFD 모델과 풍동실험과의 상관도()는 0.890 ~ 0.965로 매우 높게 나타났으며, CFD 모델 중 VBM LES CFD 모델은 상관도 0.965로 나타나 풍동실험을 가장 잘 모사하는 것으로 분석되었다.

한국어 실험 통사론의 전개

조용준 한말연구학회 2023 한말연구 Vol.64 No.34

. In this study, we address various aspects of Korean experimental syntax and explore potential avenues for future research. Within the complex realm of experimental syntax, we critically examine prior research outcomes related to the interaction between formal and informal methodologies. Unlike previous studies exemplified by Sprouse et al. (2013), existing findings suggest a lack of convergence between these two methods, particularly in the context of the Korean language. However, contrasting these results with the generally convergent outcomes observed in experimental studies conducted in English highlights the presence of cross-linguistic differences, warranting further investigation. Moving forward, we conduct a comparative analysis of disparities between expert and non-expert groups, finding similar non-convergence consistent with previous observations. In future research endeavors, empirical investigations will be necessary to pinpoint areas of divergence and unravel the underlying factors. Furthermore, a noticeable gap exists in empirical studies concerning grammaticality and acceptability within the Korean language. Despite this gap, the active exploration of the 'grammatical illusion' phenomenon prompts us to advocate for comprehensive research efforts in these domains specific to the Korean context. In parallel, recent advancements in artificial intelligence research have facilitated the availability of extensive corpora for acceptability judgments, offering essential benchmarks for evaluating the effectiveness of large-scale language models. A similar trend extends to the Korean language, exemplified by the introduction of the 'NIKL Grammaticality Judgment Corpus (2020).' Given their relevance to the enduring discourse on language acquisition, such initiatives are poised to persist. Moreover, following the release of ChatGPT's code interpreter, the lowered barriers to statistical processing have made experimental methodology more approachable, allowing for smoother engagement in experimental research and syntactic analysis. In conclusion, we anticipate a surge in experimental research, considering the advancements in AI and the improved accessibility to statistical methods. These developments are expected to contribute to the active development of experimental methodology in syntactic research.

A Simple Analysis Method to Predict the Large Amplitude Oscillatory Shear (LAOS) Flow Behavior of Viscoelastic Polymer Liquids

장갑식,안혜진,송기원,Chang, Gap-Shik,Ahn, Hye-Jin,Song, Ki-Won The Korean Fiber Society 2015 한국섬유공학회지 Vol.52 No.3

Using an Advanced Rheometric Expansion System (ARES), the dynamic viscoelastic behavior of aqueous poly(ethylene oxide) (PEO) solutions with various molecular weights and different concentrations has been investigated in large amplitude oscillatory shear (LAOS) flow fields over a wide range of strain amplitudes. In order to predict the nonlinear viscoelastic behavior of polymer liquids in strain-sweep experiments, a new analysis method including a simple empirical model was proposed and then its validity was thoroughly evaluated in this study. The results have shown that the suggested model is significant in 95% confidence level and predicts exactly the nonlinear viscoelastic behavior of polymer liquids over a whole range of strain amplitudes tested. The strain limits of linear viscoelastic response and nonlinear behavior indices were determined using this model to estimate the LAOS flow behavior in strain-sweep experiments. The master curves of strain limits and nonlinear behavior indices can be obtained by representing these data against the product of angular frequency by characteristic time. The LAOS flow behavior of polymer systems with various molecular weights and different concentrations can well be predicted from these master curves.

업무공간의 화재모델 산정을 위한 실물화재 실험

권오상,유용호,김흥열,김정현 한국방재학회 2012 한국방재학회논문집 Vol.12 No.6

The fire spread prevention in the buildings is designed to protect life and assets by prohibiting the fire spread to the adjacent space and, for this design, the outside through setting fire separations, and it is important to predict the accurate size of fire inside the unit separation. Therefore, in this paper, we have intended to select a office compartment from the building classification for use, and to propose HRR[Heat Release Rate], the engineering fire size, through the real fire experiment according to this. The fire experiment has been conducted with arranging real combustible substances and wood creep into the unit separation with 2.4(L)×3.6(W)×2.4(H) m size after analyzing fire load for the use of the buildings. The fire load of the office compartment is indicated as 19 kg/m2. In the result of the experiment, the fire experiment with real combustible substances and with wood creep are shown as 2681.7 kW/m2 and 2453.8 kW/m2, in separate. The fire size shown through these positive fire experiment can secure prediction of the fire spread of the buildings in further, and reliability on prevention designing. 건축물의 화재확대방지는 방화구획 설정을 통하여 인접 공간과 외부로의 화염의 확산을 억제를 통한 인명과 재산의 보호를위해 설계되며, 이러한 설계를 위해서는 단위 구획 내부의 화재모델을 정확히 예측하는 것이 가장 중요하다. 따라서 본 논문에서는 건축물 용도분류에서 업무공간을 선정하여 이에 따른 실물화재 실험을 통하여 공학적 화재크기인 HRR[Heat Release Rate]를 제시하고자 하였다. 화재실험은 건축물의 용도별 화재하중을 분석하여 내부의 실제 가연물 및 목재 크립을 2.4(L)×3.6(W)×2.4(H) m의 단위구획 내부에 배치하여 진행하였다. 업무시설의 화재하중은 19 kg/m2이며, 실험결과 실제 가연물을 배치한 화재실험은 2681.7 kW/m2, 목재크립을 배치한 화재실험은 2453.8 kW/m2로 나타났다. 이러한 실증적 화재실험을 통해 나타낸 화재크기는 향후 건축물의 화재확대 예측 및 방지 설계 시 신뢰도를 확보시킬 수 있을 것이다.

대형 리튬이온배터리 균일한 온도분포를 위한 설계인자 분석 및 최적설계

이정주(Jeong-Joo Lee),김지산(Ji-San Kim),장혁균(HyukKyun Chang),김창완(Chang-Wan Kim) 한국자동차공학회 2020 한국자동차공학회 학술대회 및 전시회 Vol.2020 No.11

First-harmonic nonlinearities can predict unseen third-harmonics in medium-amplitude oscillatory shear (MAOS)

Olivia Carey-De La Torre,Randy H. Ewoldt 한국유변학회 2018 Korea-Australia rheology journal Vol.30 No.1

We use first-harmonic MAOS nonlinearities from and to test a predictive structure-rheology model for a transient polymer network. Using experiments with PVA-Borax (polyvinyl alcohol cross-linked by sodium tetraborate (borax)) at 11 different compositions, the model is calibrated to first-harmonic MAOS data on a torque-controlled rheometer at a fixed frequency, and used to predict third-harmonic MAOS on a displacement controlled rheometer at a different frequency three times larger. The prediction matches experiments for decomposed MAOS measures [e3] and [v3] with median disagreement of 13% and 25%, respectively, across all 11 compositions tested. This supports the validity of this model, and demonstrates the value of using all four MAOS signatures to understand and test structure-rheology relations for complex fluids.

Manta형 무인잠수정의 대각도 받음각을 갖는 조종운동 수학모델에 관한 연구

배준영(Jun-Young Bae),손경호(Kyoung-Ho Sohn),김준(June Kim) 대한조선학회 2010 大韓造船學會 論文集 Vol.47 No.3

지진해일 범람이 해안도시에 미치는 영향에 대한 3차원 수리모형실험

김규한(Kim, Kyuhan),박형수(Park, Hyoungsu),신성원(Shin, Sungwon) 한국해안해양공학회 2012 한국해안해양공학회 논문집 Vol.24 No.6

본 연구에서 건물이 밀집되어 있는 해안도시에서의 지진해일 범람에 대한 평면수리모형실험을 수행하였다. 해안도시는 미국 서해안에 위치한 도시인 Seaside를 1/50으로 축소하여 평면수조에 설치하였다. 본 실험에서 범람지역에서의 지진해일의 파고 및 수평속도 측정하였는데, 31개 지점에서 계측하였으며 입사된 지진해일의 파고는 원형 스케일 10 m로 설정하였다. 범람양상과 속도는 건물의 위치 및 배열상태에 따라 크게 다르게 계측되었다. 또한, 도시의 주요 도로를 따라 계측된 지진해일 범람 파고 및 수평속도를 이용하여 모멘텀 플럭스(Momentum flux)를 계산하였다. 모멘텀 플럭스는 해안선에서부터 육지방향으로 파가 진행하면서 감소하는 일반적인 경향을 나타내었다. 범람파고와 모멘텀 플럭스는 도로가 형성된 구역에서 감쇄가 적게 나타났다. 본 연구를 통해 수평 유속이 구조물에 미치는 외력에 중요한 영향을 준다는 것을 알게 되었다. Laboratory experiments were conducted for tsunami inundation to an urban area with large building roughness. The waterfront portion of the city of Seaside which is located on the US Pacific Northwest coast, was replicated in 1/50 scale in the wave basin. Tsunami heights and velocities on the inundated land were measured at approximately 31 locations for one incident tsunami heights with an inundation height of approximately 10 m (prototype) near the shoreline. The inundation pattern and speed were more severe and faster in some areas due to the arrangement of the large buildings. Momentum fluxes along the roads were estimated using measure tsunami inundation heights and horizontal fluid velocities. As expected, the maximum momentum flux was near the shoreline and decreased landward. Inundation heights and momentum flux were slowly decreased through the road with buildings on each side. The results from this study showed that the horizontal inundation velocity is an important factor for the external force of coastal structures.

월류방지 구조물 설치에 따른 농업용 저수지의 침투특성

류정현(Ryu, Junghyun),이영학(Lee, Younghak),윤보라(Yoon, Bora),이달원(Lee, Dalwon) 한국방재학회 2022 한국방재학회논문집 Vol.22 No.2

본 연구에서는 노후화된 농업용저수지에 이상강우에 의한 월류를 효과적으로 방지할 수 있는 월류방지 구조물을 설치하고, 침투특성을 모형실험과 수치해석을 통해 비교분석하여 현장실용화 방안을 마련하고자 하였다. 실험 조건은 댐마루에 Gabion 옹벽, Geomembrane, Core가 복합적으로 설계된 3가지 형식의 월류방지 구조물인 계단형 Gabion 옹벽, 수직형 Gabion 옹벽, Parapet을 설치하고 홍수위부터 월류수위까지 수위를 상승시키며 관측하였다. 실험결과, 변형 및 변위결과는 전도와 파괴 등의 결함문제가 발생하지 않았고 매우 미소한 수평변위와 수직변위를 나타내어 효과적으로 월류를 방지하는 것으로 나타났다. 침윤선과 공극수압 분포 결과로부터 침투수는 상류사면에서부터 필터를 통해 Toe-drain으로 원활하게 배수되는 것으로 나타났고, 댐마루 상부에 침투수가 집중되면 하류사면 상부로 누수를 발생시켜 월류방지 구조물 하부의 안정성에 영향을 미칠 수 있는 것으로 평가되었다. 동수경사 분포는 하류사면선에서 모든 형식이 안정한 것으로 평가되었고, 잠재적인 취약부가 될 수 있는 하류사면 상부는 누수의 영향을 받을 수 있어 Geomembrane의 시공 시 섬세한 시공관리가 필요한 것으로 나타났다. 전체적으로, 적용된 3개의 월류방지 구조물 중 계단형 Gabion 옹벽은 전도 및 누수 등의 문제가 발생하지 않아 파이핑 안정성을 확보할 수 있기 때문에 다른 형식의 월류방지 구조물보다 우수한 방법으로 평가되었다. In this study, a structure that can effectively prevent overtopping caused by abnormal rainfall was installed in a deteriorative agricultural reservoir, and seepage characteristics were compared and analyzed through model experiments and numerical analysis. The experimental conditions were observed by installing a stepped gabion, vertical gabion, and parapet in combination with a gabion retaining wall, geomembrane, and core on the dam crest. Small horizontal and vertical displacements without defects were found, such as overturning and failure, to effectively prevent overtopping. A comparison of seepage line and pore water pressure results indicates that the seepage water drained smoothly to the toe drain through the filter from the upstream slope. It was perceived that the concentration of seepage water on the upper part of the dam crest might cause leakage to the upper part of the downstream slope and affect the stability of the overtopping prevention structures. The distribution of the hydraulic gradient was found to be stable in all cases on the downstream slope. The upper part of the downstream slope could be vulnerable to leakage, so careful management is required when constructing the geomembrane. Overall, among the three overtopping prevention structures applied, a stepped gabion retaining wall did not cause such problems as overturning and leakage. Therefore, it is considered better than the other types of overtopping prevention structure.