• Title/Summary/Keyword: 폭풍파

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An Experimental Study of Sand Beach Profile Evolution under Regular Waves Corresponding to Storm and Normal Conditions (규칙파 조건에서의 사질해안 폭풍파와 평상파 단면변화 실험연구)

  • Choi, Junwoo;Roh, Min
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.37 no.2
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    • pp.333-342
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    • 2017
  • In order to understand the mechanism of the cross-shore evolution of storm (barred) and normal (nonbarred) profiles of a sandy beach, the vertically two-dimensional laboratory experiment was performed with a movable bed. The beach profiles and free surface motion were measured under monochromatic wave conditions evolving the storm and normal beach profiles. The observation was conducted in the surf zone during the alternation of the two wave conditions to reach its quasi-equilibrium state. The sandbar-crest and trough and the steep berm were evolved due to the plunging breakers in the storm case, and the bar-trough was decayed due to the spilling breakers in the normal case. From the measurements, it was found that the storm wave case was in an erosion state and the normal wave case was in an accretion state. The strong undertow, which is a dominant factor of the offshore migration mechanism, was developed in the storm wave case, and the weak undertow was developed in the normal wave case. The skewness and the asymmetry of the nonlinear wave motion, which is a dominant factor of the onshore migration mechanism, was measured similarly in both cases.

Maximum Pressure and the Blast Wave Analysis of a Amount of HMX (HMX의 양에 따른 최대압력 및 폭풍파속도 분석)

  • Kwon, Hweeung;Tak, Kyongjae;Kim, Junghwan;Oh, Min;Chae, Jooseung;Kim, Hyeonsoo;Moon, Il
    • Korean Chemical Engineering Research
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    • v.52 no.6
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    • pp.706-712
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    • 2014
  • Explosives are reactive material that contain a great amount of high potential energy. They produce detonation if released suddenly, accompanied by the production of strong light, high heat, great noise and high pressure. Damage at surrounding detonation point is affected by high pressure and blast wave for explosives detonation. Consequently, analysis of pressure and blast wave is very important. This study focuses on the analysis of maximum overpressure and blast wave of explosives for safety assurance. First of all, four cases of the amount of HMX were selected. Secondly, maximum pressure and blast wave were calculated through detonation simulation along with a set of TNT and HMX quantities. The peripheral effect of detonation point was analyzed by calculating overpressure and absolute velocity and considering detonation occurred in the center of geometry by HMX. Also, maximum overpressure and blast wave of HMX were compared to equivalent amount of TNT, which was taken as a base case and verified through theoretical HMX graph. This study contributes to the base case for overpressure and blast wave of complex gunpowder containing HMX.

Trends of the Storm Wave Appearance on the East Coast Analyzed by using Long-term Wave Observation Data (장기실측 파랑자료 분석을 통한 동해안 폭풍파 출현 추세)

  • Jeong, Weon Mu;Ryu, Kyong-Ho;Oh, Sang-Ho;Baek, Won-dae
    • Journal of Korean Society of Coastal and Ocean Engineers
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    • v.28 no.2
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    • pp.109-115
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    • 2016
  • The trend in appearance of storm waves on the east coast of Korea was investigated based on long-term wave data observed at six different stations. At the four wave stations of KIOST (Sokcho, Mukho, Hupo, and Jinha), no notable trend was found during the observation period with respect to the annual average and maximum values of the significant wave height. In addition, the annual number of the appearance of storm waves showed decreasing trend at the three stations except Jinha, where slightly increasing trend of the quantity was recognized. In contrast, at Donghea ocean data buoy of KMA, abruptly increasing trend was found for the annual average and maximum of the significant wave height and for the annual number of the appearance of storm waves as well, demonstrating lack of consistency in the observation data from Donghea buoy of KMA.

Characteristics of Storm Waves at Gangneung port Based on the Wave Hindcasting (파랑 후측 모의 실험 기반 강릉항 폭풍파랑 분석)

  • Ahn, Kyungmo;Hwang, Soon-mi;Chun, Hwusub
    • Journal of Korean Society of Coastal and Ocean Engineers
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    • v.28 no.6
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    • pp.375-382
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    • 2016
  • In the present study, the wave hindcasting has been performed, and then the characteristics of storm waves at Gangnueng port was investigated, in which the high waves are observed. Comparing the numerical results with the wave measurements at Gangneung port, Niigata, and Hamada, there were good agreements between them. In particular, the Pearson correlation coefficients of significant wave heights and peak periods at Gangneung port were 0.92 and 0.72, respectively. Then the extreme wave analysis on the significant wave heights was carried out for the estimation of the frequency of storm waves. In this analysis, the storm waves over the threshold were fitted to GPD(Generalized Pareto Distribution). According to this analysis, the return period of the storm wave on February, 24, 2008, one of the large storm waves at Gangneung port, was 8.2 months. Among the computed significant wave heights larger than one-year wave, 58.3% of them were resulted from the storm, while the others were from the typhoon. Additionally, the regression analysis on the waves larger than one-month wave has been conducted, and then the relationship between the computed significant wave heights and the significant wave period, $T_{1/3}=7H_s^{0.25}$ was obtained.

Wave Hindcasting on the Storm Waves at the Korean Straits of April, 2016 (2016년 4월 대한해협 폭풍파랑 후측모의 실험)

  • Chun, Hwusub;Ahn, Kyungmo
    • Journal of Korean Society of Coastal and Ocean Engineers
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    • v.29 no.1
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    • pp.36-45
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    • 2017
  • In the present study, the storm waves at the Korean Straits of April, 2016 have been reproduced by the wave hindcasting, and then their characteristics were investigated. Before the wave hindcasting, the wave measurements at the Korean Straits were analyzed. The analysis showed that the waves at the Korean Straits were dominated by the Northeastern waves, same as those in the East Sea. Accordingly, the wave hindcasting was been carried out with the same condition in Ahn et al. (2016). In the numerical results, the maximum significant wave height at the Korean Straits was 5.06 m, and the corresponding significant wave period was 9.2 s. The computed significant wave heights and wave periods were overestimated by 4 cm and 0.8 s, respectively. After the wave hindcasting, the computed significant wave heights and peak periods were compared with the JONSWAP relationship. This comparison showed that the storm waves at the Korean Straits were close to wind waves, not swell.

Analysis of Reinforced Concrete Panel subjected to Blast Load using Parallel and Domain Decomposition (병렬과 영역분할을 이용한 폭발하중을 받는 철근콘크리트패널의 해석)

  • Park, Jae-Won;Yun, Sung-Hwan;Park, Tae-Hyo
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.24 no.4
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    • pp.365-373
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    • 2011
  • Damage of reinforced concrete panel subjected to blast load using parallel and domain decomposition is analyzed. The numerical results are sensitive to the mesh size because blast waves are generated during the extremely short term. In order to investigate the effect of mesh size on the blast wave, the analysis results from various wave mesh size using AUTODYN, the explicit finite element analysis program, were compared with existing experimental results. The smaller mesh size was, the higher accuracy was. However, in this case, the analysis was inefficient. Therefore, in order to increase numerical efficiency, the parallel analysis using decomposed method based on Euler and Lagrangian description was performed. Finally, the decomposed method using both the structure domain based on Lagrange description and the blast wave domain based on Euler description was more efficient than the decomposed method using only the Lagrange mesh on structure domain.

A Study on the Statistical Characteristics and Numerical Hindcasts of Storm Waves in East Sea (동해 폭풍파랑의 통계적 특성과 파랑 후측모의 실험에 관한 연구)

  • Chun, Hwusub;Kang, Tae-Soon;Ahn, Kyungmo;Jeong, Weon Mu;Kim, Tae-Rim;Lee, Dong Hwan
    • Journal of Korean Society of Coastal and Ocean Engineers
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    • v.26 no.2
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    • pp.81-95
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    • 2014
  • In the present study, the statistical analysis on the storm waves in the East Sea have been carried out, and the several storm waves were reproduced by the modified WAM as a first step for the accurate and prompt forecasting and warning against the swell waves in East Sea. According to the present study, the occurrences of the storm waves from the North were the most probable, while the waves from the Northeast were most frequently observed. It was found that the significant wave heights of storm waves from the North and Northern northeast were larger than those of storm waves from the Northeast. But due to long fetch distance, the significant wave periods of storm waves from the Northesast were longer than those of North and Northern northeast. In addition to the wave analysis, the numerical experiments for the storm waves in East Sea were carried out using the modified WAM, and three periods of storm waves in 2013 were calculated. The numerical results were well agreed with wave measurements. However the numerical simulation results in shallow water region showed lower accuracies compared to deep water, which might be due to lower resolution of wind field and bottom topography caused by large grid size, 5 minute, adopted in the present study. Overall computational efficiency of the modified WAM found to be excellent compared to original WAM. It is because the modified WAM adopted the implicit scheme, thereby the present model performed 10 time faster than original WAM in computation time.

Wintertime Extreme Storm Waves in the East Sea: Estimation of Extreme Storm Waves and Wave-Structure Interaction Study in the Fushiki Port, Toyama Bay (동해의 동계 극한 폭풍파랑: 토야마만 후시키항의 극한 폭풍파랑 추산 및 파랑 · 구조물 상호작용 연구)

  • Lee, Han Soo;Komaguchi, Tomoaki;Yamamoto, Atsushi;Hara, Masanori
    • Journal of Korean Society of Coastal and Ocean Engineers
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    • v.25 no.5
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    • pp.335-347
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    • 2013
  • In February 2008, high storm waves due to a developed atmospheric low pressure system propagating from the west off Hokkaido, Japan, to the south and southwest throughout the East Sea (ES) caused extensive damages along the central coast of Japan and along the east coast of Korea. This study consists of two parts. In the first part, we estimate extreme storm wave characteristics in the Toyama Bay where heavy coastal damages occurred, using a non-hydrostatic meteorological model and a spectral wave model by considering the extreme conditions for two factors for wind wave growth, such as wind intensity and duration. The estimated extreme significant wave height and corresponding wave period were 6.78 m and 18.28 sec, respectively, at the Fushiki Toyama. In the second part, we perform numerical experiments on wave-structure interaction in the Fushiki Port, Toyama Bay, where the long North-Breakwater was heavily damaged by the storm waves in February 2008. The experiments are conducted using a non-linear shallow-water equation model with adaptive mesh refinement (AMR) and wet-dry scheme. The estimated extreme storm waves of 6.78 m and 18.28 sec are used for incident wave profile. The results show that the Fushiki Port would be overtopped and flooded by extreme storm waves if the North-Breakwater does not function properly after being damaged. Also the storm waves would overtop seawalls and sidewalls of the Manyou Pier behind the North-Breakwater. The results also depict that refined meshes by AMR method with wet-dry scheme applied capture the coastline and coastal structure well while keeping the computational load efficiently.

A Model Development for Swash Hydrodynamics Across the Shore (해안선 종단방향에서 소상파의 수동학적 거동 예측모형의 개발)

  • Hwang, Kyu-Nam;Cho, Yong-Sik
    • Journal of Korea Water Resources Association
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    • v.35 no.1
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    • pp.13-24
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    • 2002
  • In a physically realistic but simplified manner, an attempt is made in this study to develop a predictive model for swash hydrodynamics across the shore due to the storm waves on an arbitrary beach profile. Date from the SUPERTANK laboratory Data Collection Project are used for the model development, in which experiments were designed to simulate dune erosion under storm conditions at a prototype scale. The model predicts variations of swash height, velocity and period across the beach face in a swash zone. In general, the model proves to be capable of predicting variations of swash height, velocity and period across the shore. Quantitatively better predictions for the swash parameters could be achieved by improving the prediction of the beach face elevation, ymax, where the significant swash height becomes zero.

가스폭발에 의한 폭풍압의 특성에 관한 연구

  • 박승일;오규형;이진영;라선종
    • Proceedings of the Korean Institute of Industrial Safety Conference
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    • 2002.11a
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    • pp.172-177
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    • 2002
  • 가스폭발 시 폭발 압력에 의해 건물의 일부 또는 전체적인 파괴와 함께 외부에 영향을 미치는 영향은 주로 폭풍파의 압력과 고온의 화염이다. 그 중에서도 폭풍압은 건물에서의 가스폭발 시 파열면을 통과한 급격한 압력 방출에 의해 생겨나는 물리적인 현상으로 그 충격은 때에 따라서 구조물을 붕괴시킬 만큼 크다. 폭발에 의해 발생되는 폭풍압에 의한 피해가 크기 때문에 과거부터 폭풍압에 대한 연구가 계속되어 왔다.(중략)

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