합성탄성파 기록을 이용한 나이지리아의 나이저 삼각주 해안 에포메(Efomeh) 지역의 이상고압 예측

( Gabriel Efomeh Omolaiye ),( John Sunday Ojo ),( Michael Ilesanmi Oladapo ),( Elijah A. Ayolabi ) 한국지구물리·물리탐사학회 2011 지구물리와 물리탐사 Vol.14 No.1

For effective and accurate prediction of overpressure in the Efomeh field, located in the Niger delta basin of Nigeria, integrated seismic and borehole analyses were undertaken. Normal and abnormal pore pressure zones were delineated based on the principle of normal and deviation from normal velocity trends. The transition between the two trends signifies the top of overpressure. The overpressure tops were picked at regular intervals from seismic data using interval velocities obtained by applying Dix`s approximation. The accuracy of the predicted overpressure zone was confirmed from the sonic velocity data of the Efomeh 01 well. The variation to the depth of overpressure between the predicted and observed values was less than 10 mat the Efomeh 01 well location, with confidence of over 99 per cent. The depth map generated shows that the depth distribution to the top of the overpressure zone of the Efomeh field falls within the sub-sea depth range of 2655±2 m (2550 ms) to 3720±2 m (2900 ms). This depth conforms to thick marine shales using the Efomeh 01 composite log. The lower part of the Agbada Formation within the Efomeh field is overpressured and the depth of the top of the overpressure does not follow any time-stratigraphic boundary across the field. Prediction of the top of the overpressure zone within the Efomeh field for potential wells that will total depth beyond 2440 m sub-sea is very important for safer drilling practice as well as the prevention of lost circulation.

폭발에 따른 최대과압 및 충격량 평가

윤용균 ( Yong-kyun Yoon ) 대한화약발파공학회 2016 화약발파 Vol.34 No.4

Empirical model, phenomenological model, and CFD model have been used to evaluate the blast effects produced by explosion of explosives, flammable gas and liquid or dust. TNT equivalence method which is one of empirical models has been widely used as it is simple. In this study, new peak overpressure-scaled distance and scaled impulse-scaled distance equations are induced through fitting data from the curves given by TNT equivalence method. If the TNT equivalent mass is calculated, it is possible to estimate the peak overpressure and impulse using the regression equations. Differences of peak overpressure with yield factor which is a component of TNT equivalence method are found to be great in near-by distances from explosion source where the increase in overpressure is very steep, but the differences are getting smaller as the distances increase.

Experimental investigation of explosion pressures and flame propagations by wall obstruction ratios and ignition positions

박달재,Young Soon Lee 한국화학공학회 2012 Korean Journal of Chemical Engineering Vol.29 No.2

Experimental studies were carried out to investigate the effects of different ignition source locations and wall obstructions in a partially opened chamber, 235 mm in height, with a 1,000×950 mm2 cross section and with a large top-venting of area of 1,000×320mm2. Four different ignition positions such as the bottom, side, corner and top,and three wall obstacles with blockage ratios ranging from about 10 to 30% were used. The comparisons between wall obstacles in the chamber showed that the dependence of overpressure on obstruction ratios was different compared with published experiments with a large L/D ratio enclosure. This may be linked to the characteristics of the chamber. The smallest wall obstacle caused the highest overpressure, while the largest one caused the lowest overpressure. The flame propagation and pressure development were highly sensitive to the ignition positions. The bottom ignition caused the highest overpressure, while the top ignition the closest to the vent opening caused the lowest overpressure.

노천 채석장 대기소음 예측을 위한 머신러닝 모델 개발

정다희,최요순 한국자원공학회 2022 한국자원공학회지 Vol.59 No.1

In this study, machine learning models were developed to predict air overpressure resulting from blasting in an open-pit mine. A total of 924 blasting data were collected from an open-pit mine at the Mt. Yogmang located in Changwon-si, Gyeongsangnam-do, Korea. The blasting data consisted of hole length, burden, spacing, maximum charge per delay, powder factor, number of holes, ratio of emulsion, monitoring distance and air overpressure. Four algorithms including k-nearest neighbors (kNN), random forest (RF), extreme gradient boosting (XGBoost) and deep neural network (DNN) were used to train the machine learning models. Mean absolute error (MAE), mean squared error (MSE), and root mean squared error (RMSE) were analyzed to evaluate the performance of the trained models. As a result, the RF model showed superior performance with MAE, MSE and RMSE of 4.938, 42.032 and 6.483, respectively. 본 연구에서는 노천 채석장 발파에서 발생하는 대기소음을 예측하기 위한 머신러닝 모델을 개발하였다. 경상남도 창원시에 위치한 욕망산 노천 채석장에서 924개의 발파 데이터를 수집하였다. 각발파 데이터는 천공장, 저항선, 공간격, 지발당 최대장약량, 비장약량, 총 공수, 에멀전폭약 비율, 이격거리, 대기소음으로 구성되었다. 머신러닝 모델 개발을 위해 kNN (k-nearest neighbors), RF (random forest), XGBoost (extreme gradient boosting), DNN (deep neural network) 알고리즘을 사용했다. 훈련된 모델의 성능을 MAE(평균 절대 오차), MSE(평균 제곱 오차) 및 RMSE(평균 제곱근 오차)로 평가한 결과, RF 모델이 MAE, MSE, RMSE가 각각 4.938, 42.032, 6.483로 가장 우수한 성능을 보였다.

학교 급식실 소형 LPG 저장탱크 폭발에 따른 위험성 분석

전승덕(Seungdeok Jeon),이재영(Jaiyoung Lee),공하성(Hasung Kong) 한국방재학회 2024 한국방재학회논문집 Vol.24 No.4

이 연구는 국내 학교의 급식실 LPG 저장탱크에서 가스 누출 및 화재, 폭발이 발생하였을 경우 독성, 과압, 복사열의 영향 범위를 분석하여 학교의 인적⋅물적 피해 등을 파악하여 최선의 안전 대책을 마련하는 데 목적이 있다. ALOHA 프로그램을 활용하여 급식실에 설치된 1,000 kg 용량의 소형 LPG 저장탱크로에서 가스 누출, VCE, BLEVE로 인한 독성(Toxic), 과압 (Overpressure), 복사열(Blast)의 영향 범위를 분석하였다. 기상조건에 따라 최악 시나리오와 대안(현지 기상) 시나리오로 구분하고, 저장량의 차이에 따라 50%와 100%의 저장량으로 구분하여 분석하였다. 독성으로 인한 위험성은 학교 전체 지역이 사망이나 장애의 위험에 처하게 되는 결과로 나타났다. 과압으로 인한 위험성는, 학교 전체 지역의 건물들이 피괴되거나 손상을 입을 위험에 처하게 돠고, 아울러 학교 주변지역까지 건물에 손상을 줄 수 있다는 결과로 나타났다. 복사열(blast)로 인한 위험성은 최대 135 m 이내 지역까지 사망에 처할 위험에 있고, 이 밖에 지역도 2도 화상을 입을 위험에 처하게 된다는 결과로 나타났다. 또한, 독성과 과압으로 인한 위험성은 기상 상황과 LPG 저장량의 영향을 받으며, 복사열은 LPG 저장량의 영향을 받지만 기상 상황의 영향은 미미하였다. This study aimed to determine the best safety measures in case of accidental gas leakage, fire, or explosion in the LPG storage tank of a domestic school kitchen by analyzing the ranges potentially affected by toxicity, overpressure, and radiant heat. Using the Areal Locations of Hazardous Atmospheres (ALOHA) program, the range of damage impact of gas leakage, toxicity owing to VCE and boiling liquid expanding vapor explosion (BLEVE), overpressure, and radiant heat were analyzed for a 1,000 kg-capacity small LPG storage tank installed in the kitchen. It was classified into worst-case and alternative (local weather) scenarios, depending upon the weather conditions, and analyzed by dividing into 50% and 100% storage, as per the difference in storage. The observed risk of toxicity placed the entire school area at risk of death or disability. The risk of overpressure posed a threat to buildings in the entire school area and around the school. The risk of blasts revealed a risk of death up to a distance of 135 m, and the farther regions were at risk of second-degree burns. Additionally, the risks of toxicity and overpressure are affected by weather conditions and LPG storage, whereas blasts are primarily affected by LPG storage with minimal impact from weather conditions.

압축수 방식 사출장치 내부 과도압력파 모의를 위한 간이 식

김국현 한국트라이볼로지학회 2022 한국트라이볼로지학회지 (Tribol. Lubr.) Vol.38 No.6

Compressed-water-type launching devices convert the force from compressed water into force-launching underwater structures, such as torpedos and autonomous underwater vehicles. In particular, the overpressure wave in the launching tube is a critical design factor for the launching device. This paper presents a simplified formula for simulating overpressure waves in the launching tube of a compressed-water-type launching device. Scaled model experiments were performed to obtain actual measurement data of overpressure waves in a launching tube with varying piston speeds to examine the practical applicability of the simplified formula. The main factor of the simplified formula was estimated using an optimization technique. The time history of the overpressure waves was satisfactorily simulated using the estimated factor values and showed consistency with the measurement data. In addition, the trend of change by the piston speed of the estimated factors was reviewed, and the practical applicability was demonstrated. A systematic study of the factors influencing the overpressure waves in launching tubes will be possible using experimental data for more various conditions and the proposed simplified formula.

베이루트항에서 발생한 질산암모늄 폭발에 의한 영향 평가

윤용균 ( Yong-kyun Yoon ) 대한화약발파공학회 2023 화약발파 Vol.41 No.4

On August 4, 2020, 2750 tons of ammonium nitrate stored in a storage warehouse at the Port of Beirut exploded. This explosion is said to be the largest ammonium nitrate explosion ever. By applying the TNT equivalency method, TNT equivalent amount corresponding to the explosion energy of 2750 tons of ammonium nitrate was calculated, and it is found to be 856 tons. Overpressure and impulse were calculated in a range up to 3600 m from the blast using the Kingery-Bulmash explosion parameter calculator tool. As the distance from the explosion center increases, the overpressure and impulse decrease exponentially, but the overpressure decreases more significantly, showing that overpressure is more affected by distance than the impact. As a result of applying the damage criteria to evaluate the effects of overpressure and impulse on the structure, the critical distances at which partial collapse, major damage, and minor damage to the structure occur are found to be approximately 500, 800, and 2200 m from the center of the explosion, respectively. The probit function was applied to evaluate the probability of damage to structures and human body. The points where the probability of collapse, major damage, minor damage, and breakage of window-panes to structures are greater than 50% are found to be approximately 500, 810, 2200, and 3200 m, respectively. For people within 200 m from the center of the explosion, the probability of death due to lung damage is more than 99%, and the 50% probability of eardrum rupture is approximately 300 m. The points with a 100% probability of death due to skull rupture and whole body impact due to whole body displacement are evaluated to be 300 and 100 m, respectively.

Improvement Plan for Prevention Regulations to Improve Hazardous Material Safety Management

오승주,이재욱,공하성 국제문화기술진흥원 2023 International Journal of Advanced Culture Technolo Vol.11 No.3

The purpose of this study is to suggest improvement plans for prevention regulations by reflecting the toxicity, fire and explosion effects of hazardous materials factories and surrounding areas using an off-site consequence assessment program. Regarding the effects of the hydrogen cyanide leak accident, which is the 1st petroleum of the 4th class flammable liquid, Areal Locations of Hazardous Atmospheres (ALOHA) program was used to compare and analyze the extent of damage effects for toxicity, overpressure, and radiation. As a result, the toxicity was analyzed to exceed 5km in the area with Acute exposure guideline level (AEGL)-2 concentration or higher, the overpressure was 103m in the range of 1 psi or more, and the radiant heat was analyzed to be 724m in the range of 2 kw/㎡ or more. Toxicity and radiation affected the area outside the hazardous material storage area, but the overpressure was limited to the inside of the hazardous material storage area. Therefore, we propose to improve the safety management of hazardous materials by conducting a risk assessment for hazardous materials and reflecting the results in internal and external emergency response plans to prepare prevention regulations.

각형 출입구를 갖는 방호터널의 방폭밸브에 미치는 폭압 평가

방승기,신진원 한국 지열 · 수열에너지학회 2021 한국지열에너지학회논문집 Vol.17 No.4

This paper presents a study to reduce the effect of blast pressure on the blast valves installed in protection tunnels, where the shape of the tunnel entrance and the blast pocket is optimized based on the predetermined basic shape of the protective tunnels. The reliability of the numerical tunnel models was examined by performing analyses of mesh convergence and overpressure stability and with comparison to the data in blast-load design charts in UFC 3- 340-02 (DoD, 2008). An optimal mesh size and a stabilized distance of overpressure were proposed, and the numerical results were validated based on the UFC data. A parametric study to reduce the blast overpressures in tunnel was conducted using the validated numerical model. Analysis was performed applying 1) the entrance slope of 90, 75, 60, and 45 degrees, 2) two blast pockets with the depth 0.5, 1.0, and 1.5 times the tunnel width, 3) the three types of curved back walls of the blast pockets, and 4) two types of the upper and lower surfaces of the blast pockets to the reference tunnel model. An optimal solution by combining the analysis results of the tunnel entrance shape, the depth of the blast pockets, and the upper and lower parts of the blast pockets was provided in comparison to the reference tunnel model. The blast overpressures using the proposed tunnel shape have been reduced effectively.

수중발파로 인한 과압 및 진동 전파에서 메쉬크기의 영향에 대한 수치해석 연구

정호영(Hoyoung Jeong),손한암(Hanam Son),김수한(Suhan Kim),김열우(Yeolwoo Kim) 한국암반공학회 2021 터널과지하공간 Vol.31 No.6

본 연구에서는 수중발파에서 발생하는 과압, 충격량, 진동의 전파 특성을 평가하기 위하여 수행되었다. 육상에서의 발파와 비교하여 수중발파에서의 소음 및 진동의 전파 특성은 주로 물을 매개체로 하여 전파되는 차이를 가지고 있으며, 경우에 따라 다양한 매질(암반, 물, 공기 등)을 통과하면서 전파양상이 변화하는 특성도 지니고 있다. 본 연구에서는 AUTODYN을 이용하여 수중에서의 발파과정을 모사하고 발파로부터 생성된 과압, 충격량, 발파진동의 전파 특성에 대하여 분석하였다. 특히 메쉬크기가 수중발파해석으로부터 획득되는 과압, 충격량, 최대입자속도에 미치는 영향을 중점적으로 평가하였다. 전체적으로 과압과 최대입자속도는 메쉬의 크기가 증가함에 따라 감소하는 경향성을 나타내었고, 충격량은 메쉬의 크기와 함께 증가하는 경향을 보였다. 또한 본 연구의 결과로부터 메쉬 크기에 대한 의존성은 장약량과 환산거리에 따라서도 다르게 나타날 수 있다는 것을 확인하였다. This study performed to investigate the propagation characteristics of overpressure, impulse, vibration in underwater blasting. The difference between air blasting and underwater blasting is that noise and vibration propagate through water as a medium. In some cases, the noise and vibration propagates through various media (rock, water, air, etc.). In this study, the underwater blasting was simulated using AUTODYN, and the propagation characteristics of overpressure, impulse and vibration induced by blasting were analyzed. We mainly focused on the effect of mesh size on the overpressure, impulse and peak particle velocity from the underwater blasting simulation. The numerical results indicated that the overpressure and peak particle velocity tended to decrease as the mesh size increased, while the impulse increased with the mesh size. The results also indicated that the mesh dependence varied depending on the explosive charge and scaled distance.