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A Parametric Study of Ridge-cut Explosive Bolts using Hydrocodes
Juho Lee,Jae-Hung Han,YeungJo Lee,Hyoungjin Lee 한국항공우주학회 2015 International Journal of Aeronautical and Space Sc Vol.16 No.1
Explosive bolts are one of pyrotechnic release devices, which are highly reliable and efficient for a built-in release. Among them, ridge-cut explosive bolts which utilize shock wave generated by detonation to separate bolt body produce minimal fragments, little swelling and clean breaks. In this study, separation phenomena of ridge-cut explosive bolts or ridge-cut mechanism are computationally analyzed using Hydrocodes. To analyze separation mechanism of ridge-cut explosive bolts, fluid-structure interactions with complex material modeling are essential. For modeling of high explosives (RDX and PETN), Euler elements with Jones-Wilkins-Lee E.O.S. are utilized. For Lagrange elements of bolt body structures, shock E.O.S., Johnson-Cook strength model, and principal stress failure criteria are used. From the computational analysis of the author’s explosive bolt model, computational analysis framework is verified and perfected with tuned failure criteria. Practical design improvements are also suggested based on a parametric study. Some design parameters, such as explosive weights, ridge angle, and ridge position, are chosen that might affect the separation reliability; and analysis is carried out for several designs. The results of this study provide useful information to avoid unnecessary separation experiments related with design parameters.
Effect of Oxygen Content on Fission Product Release Behavior
JuHo Lee,JaeWon Lee,Seok Min Hong,ChangHwa Lee,YungZun Cho 한국방사성폐기물학회 2022 한국방사성폐기물학회 학술논문요약집 Vol.20 No.1
In KAERI, the nuclide management technology is currently being developed for the reduction of disposal area required for spent fuel management. Among the all fission products of interest, Cs, I, Kr, Tc are considered to be significantly removed by following mid-temperature and high-temperature treatment, however, a difficulty of spent-fuel thermal treatment experiment limits the development of such thermal treatment. In this study, we applied our previously developed two-stage diffusion release model coupled to UO2 oxidation model to the development of optima thermal treatment scenario. Since the formation of cesium pertechnetate should be avoided and the fission release behavior is considerably affected by the extent of oxygen, we obtained oxygen-content dependent model parameters for two-stage fission release model and applied the model to the evaluation of fission release behavior to different oxygen content and thermal treatment procedure. It was found that the developed fission release model closely describes the experimental behavior of fission product of interest, implying a validity of model prediction and the thermal treatment condition reducing the chemical reaction between cesium and technetium could be developed.
A Parametric Study of Ridge-cut Explosive Bolts using Hydrocodes
Lee, Juho,Han, Jae-Hung,Lee, YeungJo,Lee, Hyoungjin The Korean Society for Aeronautical and Space Scie 2015 International Journal of Aeronautical and Space Sc Vol.16 No.1
Explosive bolts are one of pyrotechnic release devices, which are highly reliable and efficient for a built-in release. Among them, ridge-cut explosive bolts which utilize shock wave generated by detonation to separate bolt body produce minimal fragments, little swelling and clean breaks. In this study, separation phenomena of ridge-cut explosive bolts or ridge-cut mechanism are computationally analyzed using Hydrocodes. To analyze separation mechanism of ridge-cut explosive bolts, fluid-structure interactions with complex material modeling are essential. For modeling of high explosives (RDX and PETN), Euler elements with Jones-Wilkins-Lee E.O.S. are utilized. For Lagrange elements of bolt body structures, shock E.O.S., Johnson-Cook strength model, and principal stress failure criteria are used. From the computational analysis of the author's explosive bolt model, computational analysis framework is verified and perfected with tuned failure criteria. Practical design improvements are also suggested based on a parametric study. Some design parameters, such as explosive weights, ridge angle, and ridge position, are chosen that might affect the separation reliability; and analysis is carried out for several designs. The results of this study provide useful information to avoid unnecessary separation experiments related with design parameters.
Pyroshock Prediction of Ridge-Cut Explosive Bolts Using Hydrocodes
Lee, Juho,Hwang, Dae-Hyun,Jang, Jae-Kyeong,Kim, Dong-Jin,Lee, YeungJo,Lee, Jung-Ryul,Han, Jae-Hung Hindawi Limited 2016 Shock and vibration Vol.2016 No.-
<P>Pyrotechnic release devices such as explosive bolts are prevalent for many applications due to their merits: high reliability, high power-to-weight ratio, reasonable cost, and more. However, pyroshock generated by an explosive event can cause failures in electric components. Although pyroshock propagations are relatively well understood through many numerical and experimental studies, the prediction of pyroshock generation is still a very difficult problem. This study proposes a numerical method for predicting the pyroshock of a ridge-cut explosive bolt using a commercial hydrocode (ANSYS AUTODYN). A numerical model is established by integrating fluid-structure interaction and complex material models for high explosives and metals, including high explosive detonation, shock wave transmission and propagation, and stress wave propagation. To verify the proposed numerical scheme, pyroshock measurement experiments of the ridge-cut explosive bolts with two types of surrounding structures are performed using laser Doppler vibrometers (LDVs). The numerical analysis results provide accurate prediction in both the time (acceleration) and frequency domains (maximax shock response spectra). In maximax shock response spectra, the peaks due to vibration modes of the structures are observed in both the experimental and numerical results. The numerical analysis also helps to identify the pyroshock generation source and the propagation routes.</P>
Lee, Juho,Lee, Changkyu,Kim, Tae Hyung,Lee, Eun Seong,Shin, Beom Soo,Chi, Sang-Cheol,Park, Eun-Seok,Lee, Kang Choon,Youn, Yu Seok Elsevier 2012 Journal of controlled release Vol.161 No.3
<P>Inhalable deoxycholic acid-modified glycol chitosan (DOCA-GC) nanogels containing palmityl acylated exendin-4 (Ex4-C16) were prepared by self-assembly and characterized physicochemically. The lung deposition of DOCA-GC nanogels was monitored using an infrared imaging system, and the hypoglycemia caused by Ex4-C16-loaded DOCA-GC nanogels was evaluated after pulmonary administration in type 2 diabetic db/db mice. The cytotoxicities and lung histologies induced by DOCA-GC nanogels were examined in human lung epithelial cells (A549 and Calu-3) and db/db mice, respectively. Results showed that the DOCA-GC nanogels prepared were spherical and compact and had a diameter of ~220 nm. Although the incorporation of Ex4-C16 (50.97.8%) into DOCA-GC nanogels was significantly lower than that of Ex4 (81.44.9%), the Ex4-C16 release from DOCA-GC nanogels was greatly delayed vs. Ex4. DOCA-GC nanogels were deposited rapidly after pulmonary administration and remained in the lungs for ~72 h. Furthermore, the hypoglycemic duration of inhaled Ex4-C16 nanogels was much greater than that of Ex4 nanogels in db/db mice. Cytotoxicity results of DOCA-GC nanogels were considered acceptable, and the tissue histologies of mouse lungs administered nanogels did not show any significant difference vs. control lungs. The authors believe that Ex4-C16 DOCA-GC nanogels offer a long-acting inhalation delivery system for treating type 2 diabetes.</P>