• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.41 no.10
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• pp.827-832
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• 2013

Heating wire cutting type separation mechanism has been widely used for cube satellite applications due to its design constraints such as small size of $10cm{\times}10cm{\times}10cm$ and light weight of less than 1kg. In addition, usage of pyro technic device is not allowed for cube satellite application. The conventional methods have some disadvantages of relatively small mechanical constraint force and the system complexity for the multi-deployable systems. In this paper, a separation nut type non-explosive separation mechanism has been proposed and investigated. The effectiveness of the design has been verified through the qualification tests of the mechanism.

• Journal of Korean Society for Quality Management
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• v.50 no.4
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• pp.793-810
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• 2022

Purpose: As improving the search performance of aviation security equipment is considered essential, this study proposes the need for research on how to find an optimized test sequence that can reduce test time and operator power during the search function test of explosive detection systems. We derive the weights and work difficulty adjustment factor required to find the optimized test order. Methods: First, after setting the test factors, the time of each test and the difficulty scale determined by the worker who performed the test directly were used to derive weights. Second, the work difficulty adjustment coefficient was determined by combining the basic weight adjustment factor and corresponding to the body part used by the test using objective rating. Then the final standard time was derived by calculating the additional weights for the changeability of the test factors. Results: The order in which the final standard time is minimized when 50 tests are performed was defined as the optimized order. 50 tests should be conducted without duplication and the optimal order of tests was obtained when compared to previously numbered tests. As a result of minimizing the total standard time by using Excel's solver parameters, it was reduced by 379.14 seconds, about 6.32 minutes. Conclusion: We tried to express it in mathematical formulas to propose a method for setting an optimized test sequence even when testing is performed on other aviation security equipment. As a result, the optimal test order was derived from the operator's point of view, and it was demonstrated by minimizing the total standard time.

• Explosives and Blasting
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• v.41 no.4
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• pp.29-40
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• 2023

Rock blasting is utilized in various fields such as mining, tunneling, and the construction of underground structures. The role of rock blasting technology has became increasingly significant with the growing utilization of underground cavity. Blast hole pressure, generated during rock blasting, is a critical variable directly impacting factors such as crushing and blast vibration. It stands out as one of the most important parameters for assessing explosive performance and predicting blasting effects. While blast hole pressure has been studied by several researches, comparisons are challenging due to variations in experimental conditions such as explosive type, charge, and blasting conditions. In this study, blast hole pressure sensors and observation hole pressure sensors were developed to measure pressure during single-hole blasting, The experimental results were then used to discuss the propagation characteristics of pressure around the blast hole and the corresponding blast vibration.

• Journal of Korean Society of Steel Construction
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• v.28 no.2
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• pp.65-74
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• 2016

A finite element dynamic simulation is performed to gain an insight about the stiffened blast wall structures subjected to blast loading. The simulation was verified using qualitative and quantitative comparisons for different materials. Based on in-depth examination of blast simulation recordings, dynamic behaviors occurred in the blast wall against the explosion are determined. Subsequent simulation results present that the blast wall made of the high performance steel performs much better in the shock absorption. In this paper, the existing finite element shock analysis using the LS-DYNA program is further extended to study the dynamic response of the stiffened blast wall made of the high-performance steel considering high strain-rate effects. The numerical results for various parameters were verified by comparing different material models with dynamic effects occurred in the stiffened blast wall from the explosive simulation.

• Explosives and Blasting
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• v.39 no.1
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• pp.1-9
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• 2021

As the national economic growth and the rapid increase in industrial structures are aging, the demand for removing steel structures is increasing, and research on improving the penetration performance of the linear shape charge explosives. In the study, numerical analyses were performed on the effect of the type of explosive used in the self-made shape charging container and the initiation method on the cutting performance of the steel plate and the effect on the shaped explosive installed close to it. ANSYS LS-DYNA, which can analyze the large deformation problem of materials due to explosion, was used, and an ALE(Arbitrary-Lagrange-Eulerian) model was applied that enables interlocking analysis of gases, liquids, and solid.

• Journal of the Korea Society for Simulation
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• v.33 no.3
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• pp.27-35
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• 2024

Generally, an Linear Shaped Charge(LSC) is used for cutting a mechanical structure of various weapon systems. The penetration performance of an LSC is subjected to the type of explosive, the amount of explosive charge per unit length, the type of sheath material, stand-off distance from the target etc. In addition, the non-uniform cross-sectional shape originated from the manufacturing process may affect penetration performance. In this study, in order to analyze the penetration performance of an LSC, Computed Tomography(CT) images of its internal shape were taken and penetration experiments of the LSC were performed on a square metal bar. The experimental results showed that the penetration depths varied depending on the longitudinal position of the LSC, and at some locations, did not meet the required cutting performance. The LSC used in the experiment was manufactured to be able to cut a 4 mm plate, but in the results of the penetration performance experiment, there were many locations where the penetration depth was less than 4 mm. To find this reason, the penetration performance that did not meet the required cutting performance was simulated through AUTODYN based numerical analysis to confirm whether the LSC is cut in the plate. Through numerical analysis, it was confirmed that the penetration performance of an LSC varies depending on the thickness of the incision target due to the distribution of stress.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.19 no.3
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• pp.10-15
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• 2011

The separation actuator for the small satellite should fix satellite appendages with high clamping force. After operation, it has to be separated from the satellite body without any damage on satellite system and release the appendages such as a solar panel and an antenna successfully. Therefore, we invent a non-explosive separation actuator for the small satellite which generates low shock and is resettable. In order to confirm performance of the proposed separation actuator, we carried out experiments for separation time, maximum preload for activation, and shock level.

• Journal of the Korean Society of Propulsion Engineers
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• v.9 no.1
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• pp.27-34
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• 2005

The present work has been developed the study of interpretation of separation behavior in gas expansion separation(GES) bolt which has the separation characteristics without fragmentation and minimum pyre-shock during the operation of the explosive bolt. In order to obtain the performance of minimum pyre-shock, the present work used non-compressive material instead of separation explosives. The use of the interpretation processor could be extensively helped to design the shape and the amount of explosives in the explosive bolt having complex geometry, and to analyse the separation behavior during the operation. It is also proved that the GES bolt is the most suitable the separation system necessary to minimum pyre-shock and non fragmentation compare with others.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2004.10a
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• pp.95-98
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• 2004

The present work has been developed the study of interpretation of separation behavior in gas expansion separation(GES) bolt which has the separation characteristic without fragmentation and minimum pyre-shock during the operation of the explosive bolt. In order to obtain the performance of minimum pyro-shock, the present work used non-compressive material instead of separation explosives. The use of the interpretation processor could be extensively helped to design the shape and the amount of explosives in the explosive bolt having complex geometry, and to analyse the separation behavior during the operation. It is also proved that the GES bolt is the most suitable the separation system necessary to minimum pyro-shock and non fragmentation compare to others.

• Explosives and Blasting
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• v.41 no.1
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• pp.19-31
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• 2023

There are various types of explosives, and each explosive has different characteristics such as water resistance, energy required for detonation, and crushing power, so understanding the characteristics of explosives is important for safe use and performance improvement. Computer simulation is used indirectly along with various experiments to understand the characteristics of explosives, and a state equation is used to express the explosive detonation process through computer simulation. In this study, the explanation of JWL EOS, which is mainly used among the state equations of explosives, and the cylinder expansion experiment to calculate the coefficient of JWL EOS were implemented as ANSYS AUTODYN and compared and analyzed with the actual experimental results. As a result, an error rate of around 20% occurred, and it was found that the overall change pattern of pressure and energy was consistent with the previously published experimental results.