A Study on the Improvement of EXPLOSION TEST on Blast-Proof Door

Sangho Baek J-INSTITUTE 2021 International Journal of Military Affairs Vol.6 No.2

Purpose: In this paper, the development direction of the blast-proof door verification test was suggested through analysis of the blast-proof door verification test that has been conducted so far. Blast-proof doors are protective equipment that withstands storm pressure from enemy weapons at the outermost part of the build-ing in case of emergency, and must be verified before installation. To ensure the durability and stability of the blast-proof door, the explosion-proof test of the blast-proof door has been conducted four times since 2016. Method: In the meantime, as domestic blast-proof door certified products came out through explosion-proof tests of blast-proof doors, it has opened the way for domestic blast-proof doors to be used instead of expensive overseas products in domestic protection facilities and evacuation facilities. Based on the progress of the last four demonstration tests and certification results, the opinions of the Korea Gas Safety Corporation, the De-fense Installations Agency, and explosion-proof door manufacturers were synthesized to derive improvements. In addition, the explosion-proof door certification procedure and certification standards were reviewed, and the explosion-proof door manufacturing process and documents submitted by the companies that applied for the certification test were reviewed. Results: As a result of reviewing the requests of the host organization and explosion-proof door manufac-turers in the process of preparing the demonstration test such as purchasing TNT, preparing the test site, con-ducting an explosion test, and issuing a certificate, the need for improvement in the implementation of the demonstration test was identified. Improvement needs were identified in the agency in charge of the demon-stration test, the verification method, the method of measuring the displacement of the explosion-proof door after the explosion, and the alternative method of the demonstration test. Conclusion: I suggested that the explosion-proof test of the blast-proof door be supervised by the military institution. Through this, it is expected that the work related to the explosion-proof test will be more efficiently controlled. Also I concluded that it is necessary to supplement the method of measuring the displacement of the blast-proof door, and consider implementing a reduced-scale explosion test. In addition, it is proposed to supplement and develop the blast-proof door blasting demonstration test through computer simulation using the empirical test data accumulated in the future. Once the explosion-proof test of the blast door is improved as suggested in the conclusions, it is clear that the result will be of benefit to the military, companies, and ulti-mately the people who will be provided with certified high-quality blast-proof doors and installed in the protec-tion facilities.

Blasting wave pattern recognition based on Hilbert-Huang transform

Li, Xuelong,Wang, Enyuan,Li, Zhonghui,Bie, Xiaofei,Chen, Liang,Feng, Junjun,Li, Nan Techno-Press 2016 Geomechanics & engineering Vol.11 No.5

Rockburst is becoming more serious in Chinese coal mine. One of the effective methods to control rockburst is blasting. In the paper, we monitored and analyzed the blasting waves at different blast center distances by the Hilbert-Huang transform (HHT) in a coal mine. Results show that with the increase of blast center distance, the main frequency and amplitude of blasting waves show the decreasing trend. The attenuation of blasting waves is slower in the near blast field (10-75 m), compared with the far blast field (75-230 m). Besides, the frequency superposition phenomenon aggravates in the far field. A majority of the blasting waves energy at different blast center distances is concentrated around the IMF components 1-3. The instantaneous energy peak shows attenuation trend with the blast center distance increase, there are two obvious energy peaks in the near blast field (10-75 m), the energy spectrum appears "fat", and the total energy is greater. By contrast, there is only an energy peak in the far blast field, the energy spectrum is "thin", and the total energy is lesser. The HHT three dimensional spectrum shows that the wave energy accumulates in the time and frequency with the increasing of blast center distance.

경남 창원시 진해 지역의 발파진동 예측에 관한 연구

이충원(Lee, Chung-Won) 한국방재학회 2017 한국방재학회논문집 Vol.17 No.4

국가기반시설의 확충을 위한 발파 등 각종 건설공사에 기인한 진동 문제는 민원에 의해 그 중요성이 점증하고 있는 실정이다. 진동은 대표적인 환경피해 요인으로, 건설방재적 관점에서도 대단히 큰 의미를 갖는다. 본 연구에서는 경남 창원시 진해 지역에서 실규모 시험발파를 수행하여 심발발파 종류에 따른 파쇄암의 입경을 분석하고, 이에 대한 진동 계측 결과를 통해 신뢰수준 95%의 자승근식을 발파진동 추정식으로 제안하였다. 실규모 시험발파 결과와 비교시, 거리에 따른 발파진동 추정치는 미 광무국 식이 실규모 시험발파 결과보다 보수적인 것으로 확인되었다. 따라서, 현장 여건을 고려한 최적의 발파설계를 위해서는 실규모 시험발파를 통한 진동의 계측 및 이에 근거한 발파진동 추정식을 도출할 필요가 있다. 그러나, 터널 굴착 등의 실제 발파시에는 진동을 함께 계측함으로써 주변의 보안물건에 피해가 발생하지 않도록 유념하여야 할 것이다. Vibration problems due to a number of construction works including blasting for infrastructure development are getting important because of a civil appeal. Vibration is representative factor of environmental damage, hence, this has great meaning to prevent potential disasters. In this study, through the real-scale test blasting performed at Jinhae area, Changwon, Gyeongnam, the diameter of blasted rock was analyzed with blasting method, and square root equation(SRE) with 95% confidence level was proposed for prediction of blasting-induced vibration. From the comparison between tendencies of blasting-induced vibration with distance, it was confirmed that the predicted blasting-induced vibration by USBM(U.S. Department of Interior, Bureau of Mines) equation was more conservative than that by proposed equation based on the real-scale test blasting. Therefore, measuring vibration and determining equation for prediction of blasting-induced vibration through the real-scale test blasting are needed for optimal blast design considering field condition. However, in the case of real blasting including tunnel excavation, measuring vibration is required for damage prevention to surrounding facilities.

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.

호평벼와 남평벼의 혼합재배에 의한 도열병 방제와 레이스 다양성의 변화

오인석,민지영,조명길,노재환,신동범,송진,김명기,조영찬,김병련,한성숙 한국식물병리학회 2008 식물병연구 Vol.14 No.3

Mixed-planting of two rice cultivars, HP (‘Hopyeongbyeo’) and NP (‘Nampyeongbyeo’), having a dissimilar susceptibility to rice blast was practiced for chemical-free control of rice blast in the field. The HP/NP combination was selected for applying under mechanized agricultural conditions. Because they have similar genetic characteristics such as seed germination and heading time, culm length, rice quality and size of rice grains except susceptibility to blast. Incidence of panicle blast was reduced 50.4% compare with supposed blast incidence by HP/NP mixed-planting when the seeds of two cultivars were combined 1 to 1 as weight. Supposed blast incidence was estimated from reduction of rice blast caused by addition of a resistant cultivar NP. Race diversity of Magnaporthe oryzae was examined for correlation with control effect of HP/NP mixed-planting on rice blast. The population of dominant race KJ-101 was diminished and replaced with various co-existing races and eleven new races were appeared in mixed-planting plot. Total number of race isolated from mixedplanting plot was not largely different from mono-culture. However, detection frequency of the new race was increased and variation of the population size of each race was decreased in mixed-planting plots. It was shown that a biased community with a dominant race (KJ-101 or KI-181) was altered to a balanced one of coexisting races. From these results, it was supposed that the balanced diversity among co-existing races within a community might be correlated to control effect by HP/NP mixed-planting on rice blast. Further more, it should be studied that genetic characteristics of the individual race including a virulence on cv. HP and NP was examined for verifying a correlation of mixed-planting effect and race diversity. Mixed-planting of two rice cultivars, HP (‘Hopyeongbyeo’) and NP (‘Nampyeongbyeo’), having a dissimilar susceptibility to rice blast was practiced for chemical-free control of rice blast in the field. The HP/NP combination was selected for applying under mechanized agricultural conditions. Because they have similar genetic characteristics such as seed germination and heading time, culm length, rice quality and size of rice grains except susceptibility to blast. Incidence of panicle blast was reduced 50.4% compare with supposed blast incidence by HP/NP mixed-planting when the seeds of two cultivars were combined 1 to 1 as weight. Supposed blast incidence was estimated from reduction of rice blast caused by addition of a resistant cultivar NP. Race diversity of Magnaporthe oryzae was examined for correlation with control effect of HP/NP mixed-planting on rice blast. The population of dominant race KJ-101 was diminished and replaced with various co-existing races and eleven new races were appeared in mixed-planting plot. Total number of race isolated from mixedplanting plot was not largely different from mono-culture. However, detection frequency of the new race was increased and variation of the population size of each race was decreased in mixed-planting plots. It was shown that a biased community with a dominant race (KJ-101 or KI-181) was altered to a balanced one of coexisting races. From these results, it was supposed that the balanced diversity among co-existing races within a community might be correlated to control effect by HP/NP mixed-planting on rice blast. Further more, it should be studied that genetic characteristics of the individual race including a virulence on cv. HP and NP was examined for verifying a correlation of mixed-planting effect and race diversity.

건공화 공법의 발파 성능 평가를 위한 현장 시험에 관한 연구

이승훈(Lee, Seung Hun),정성훈(Chong, Song-Hun),최형빈(Choi, Hyung Bin) 대한토목학회 2022 대한토목학회논문집 Vol.42 No.2

암반층이 얕은 깊이에서 출현하는 국내 지층 조건과 지하 공간의 활용도 증가로 인해서, 발파에 의한 굴착은 여전히 이용되고 있다. 발파 천공 이후에 존재하는 물이 있는 조건에서 실시되는 표준 발파는 폭굉압력 감소, 일정 장약량 사용, 디커플링과 같은 기술적인 어려움이 있다. 하지만, 기존의 표준 발파 공법을 대체할 만한 공법이 없는 실정이다. 본 논문에서는 건공화 펌프 시스템을 이용하여, 천공 내부에 존재하는 물을 제거하는 건공화 ANFO (Ammonium Nitrate Fuel Oil) 발파와 발파 성능의 비교를 위해서 추가적으로 표준 발파를 수행하였다. 각각의 발파 공법에서 계측된 진동 속도 데이터들과 환산거리의 함수로 이루어진 경험적인 발파진동 추정식을 이용하여, 최소제곱법에 의한 선형회귀분석을 실시하고, 궁극적으로 발파 성능을 정량적으로 분석하였다. 그 결과, 건공화 ANFO 발파에서 진동 감쇠가 더 크게 발생하고, 암반 파쇄에 더 많은 에너지를 소비하여, 더 가까운 거리에서 진동 허용 기준을 만족하는 진동 속도를 보였다. 또한, 표준 발파의 발파 진동 영향권이 건공화 ANFO 발파보다 더 멀리 있고, 발파 패턴의 범위가 더 넓은 것으로 나타났다. 본 연구에서 수행된 현장 발파 실험 결과로부터, 건공화 ANFO 발파 공법의 발파 성능이 효율적임을 확인하였다. The existence of shallow bedrock and the desire to use underground space necessitate the use of blasting methods. The standard blasting method under water after drilling is associated with certain technical difficulties, including reduced detonation power, the use of a fixed charge per delay, and decoupling. However, there is no blasting method to replace the existing blasting method. In this paper, a dry hole charged with ANFO blasting is assessed while employing a dry hole pumping system to remove water from the drill borehole. Additional standard blasting is also utilized to compare the blasting performances of the two methods. The least-squares linear regression method is adopted to analyze the blasting vibration velocity quantitatively using the measured vibration velocity for each blasting method and the vibration velocity model as a function of the scaled distance. The results show that the dry hole charged with ANFO blasting will lead to greater damping of the blasting vibration, more energy dissipation to crush the surrounding rock, and closer distances for the allowable velocity of the blasting vibration. Also, standard blasting shows much longer influencing distances and a wider range of the blasting pattern. The pilot test confirms the blasting efficiency of dry hole charged with ANFO blasting.

국내 벼 품종의 도열병 저항성 유전자 유전형 분석

이현숙(Hyun-Sook Lee),하수경(Su-Kyung Ha),이창민(Chang-Min Lee),박현수(Hyun-Su Park),정지웅(Ji-Ung Jeung) 한국육종학회 2022 한국육종학회지 Vol.54 No.4

Rice blast is one of the most serious agricultural diseases in the world. Rice blast can be managed using low nitrogen fertilizers, treatment with chemical fungicides, and the most effective resistant varieties. Many genetic resources have been investigated and used along with molecular markers to breed blast-resistant rice varieties. In this study, the genetic diversity of blast resistance genes using 27 functional/linked markers and rice blast incidence over three years was investigated in 296 Korean rice varieties. Blast incidence was determined using a 0-9 scoring system (0=no lesions to 9=dead leaves) in nursery tests. The blast incidence of 296 rice varieties showed a significant correlation between years (r>0.64, p<0.001). The 261 Japonica varieties showed blast resistance compared to 114 mid-late maturing varieties or 96 medium-maturing varieties. 35 Tongil-type varieties also exhibited greater resistance than Japonica varieties. DNA marker-trait association analysis was conducted using 27 DNA markers linked to 19 blast resistance genes. Twelve DNA markers showed significant associations with the average blast incidence over 3 years. The ‘9871.T7E’ marker linked with Pi40 was strongly associated with blast disease, with a phenotypic variance of 24% over 3 years (p<0.001). Among the varieties harboring the Pi40 allele, early maturing varieties accounted for 87%. These results imply that the blast resistance of early maturing Korean varieties is associated with the Pi40 gene. These results will be beneficial for breeding blast-resistant rice in Korea.

탄약고 슬라이딩 방폭문 설계기준 및 성능평가방법

심관보,김병진,구현주 표준인증안전학회 2023 표준인증안전학회지 Vol.13 No.1

Sliding blast doors used in ammunition warehouses are architectural structures that must be designed to ensure safety, usability, and durability, and to consider eco-friendliness. Blast doors generally require a structural analysis that considers the dynamic behavior characteristics of the material because the explosion load acts in a very short time. Blast doors are designed by predicting the behavior of blast-proof doors based on the results of dynamic structural analysis. In the simulation method, output information, that is, structural analysis results, is calculated differently according to input information such as structural modeling, boundary conditions, and material properties of members. Demonstration tests on blast doors evaluate the safety and usability of blast-proof doors. Rotation ductility and displacement ductility are used as indicators for evaluating the safety of blast doors. The usability of the blast door is checked using a checklist, and it must be possible to open and close the blast door. In this study, the performance of the ammunition warehouse blast door was evaluated through a proof test of the blast door using TNT 125kg and a separation distance of 7.12m. For the purpose of establishing a design method for blast doors, the input information necessary for designing blast doors is considered, and the results obtained through structural analysis are compared with those obtained through proof-of-concept tests on blast doors. This study establishes the design process of sliding blast doors for ammunition magazines subjected to explosive loads.

Improvement of fluid penetration in soil by plasma blasting

장현식,백인준,송재용,이근춘,장보안 한국지질과학협의회 2022 Geosciences Journal Vol.26 No.6

Plasma blasting by high-voltage arc discharge was performed in laboratory-scale soil samples to investigate fluid penetration. A plasma blasting device with a large-capacity capacitor and columnar soil samples with a diameter of 80 cm and a height of 60 cm were prepared. The columnar soil samples were made of sand and silt mixed in a 7:3 ratio (the A samples) or a 9:1 ratio (the B samples). When fluid was injected by pressure without plasma blasting, fluid penetrated into the soil only near the borehole, and the penetration area ratio was less than 10%. In further tests, fluid was injected by plasma blasting with different discharge energies of 1–27 kJ. When plasma blasting was performed once in the A samples, the penetration area ratios of the fluid were 16–25%; after five consecutive blasts, the penetration area ratios were 30–48%. When five consecutive plasma blasts were carried out on the B samples, the fluid penetration area ratios were 33–72%. This difference indicates that the fluid penetration area increases with higher discharge energy of plasma blasting and with a greater number of blasts. The fluid penetration radius was calculated to assess the fluid penetration volume. When the fluid was injected by hydraulic pressure only, the penetration radius was 9–12.4 cm, whereas the penetration radius was 27–33.2 cm when blasting was performed five times. The radius was increased by up to 200% by plasma blasting. In the field tests, the fluid injection in the test hole subjected to plasma blasting was greater by about 170% compared with the control test hole, in which the fluid was injected only by hydraulic pressure. In addition, the electrical resistivity around the test hole subjected to plasma blasting was markedly lower, and fluid diffused from this test hole to a minimum radius of 2 m. These results indicate that a cleaning agent will penetrate further and the remediation efficiency of contaminated soil will be improved if plasma blasting is applied for in situ cleaning of low-permeability contaminated soil.

Performance Assessment of the Circular-Cut Blasting by Numerical Analysis

Jong, Yonghun,Lee, Chung-In,Jeon, Seokwon,Cho, Young-Dong,Shim, Dong-Soo 한국암반공학회 2004 Geosystem engineering Vol.7 No.3

The most important operation in the tunnel blasting procedure is to create an opening in the face in order to develop more free surface in the rock mass. This operation is highly dependent on the cut holes. In general, the bum-cut or V-cut is commonly adopted to blast the cut section. But, these traditional methods often raise problems. There are instances (a) that the actual advance is considerably less than the designed advance depending on the rock mass, (b) that they cannot sometimes enlarge the free surface efficiently and (c) that the blast vibration resulted from the cut blast exceeds the allowable vibration level. In order to resolve the problems, many different kinds of the cut blast can be considered. The objectives of this study are to suggest a new cut blast (named as 'circular-cut') using pre-splitting technique with an array of large empty holes and blast holes and to investigate the efficiency of the circular-cut. The distinct element computer program, particle flow code (PFC2D), was used to investigate the effect of the cut blast. By using the program, we could identify (a) the optimal spacing between the large empty holes and blast holes surrounding a central hole and (b) the optimal amount of explosive charge for the central hole. We could also evaluate the vibration attenuation rate of the cut blast obtained by pre-splitting. The optimal values of the above parameters favorably agreed with the field-measured data. In addition, a series of numerical simulations using the optimal values showed that the suggested method could reduce the blast vibration caused by the cut blast in comparison with the traditional methods.