• Journal of the Korean Society of Propulsion Engineers
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• v.12 no.6
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• pp.12-20
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• 2008

The efficient plan and numerical methods for development of the interior ballistics code have been investigated. The schemes of the numerical code for the moving boundary with the projectile movement have been compared and verified through the free piston motion problem. The combustion of solid propellants and the pressure gradient in the chamber by the porosity effect have been predicted based on the numerical calculation of the initial combustion of the interior ballistics. Computerization techniques of the fundamental schemes and plans for development of the numerical analysis code for the interior ballistics have been obtained.

• 한국전산유체공학회:학술대회논문집
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• 1999.11a
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• pp.77-84
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• 1999

Numerical design optimization techniques are implemented for the improvement of the ram accelerator performance. The design object is to find the minimum ram tube length required to accelerate projectile from initial velocity $V_0$ to target velocity $V_e$. The premixture is composed of $H_2,\;O_2,\;N_2$ and the mole numbers of these species are selected as design variables. The objective function and the constraints are linearized during the optimization process and gradient-based Simplex method and SLP(Sequential Linear Programming) have been employed. With the assumption of two dimensional inviscid flow for internal flow field, the analyses of the nonequilibrium chemical reactions for 8 steps 7 species lave been performed. To determined the tube length, ram tube internal flow field is assumed to be in a quasi-steady state and the flow velocity is divided into several subregions with equal interval. Hence the thrust coefficients and accelerations for corresponding subregions are obtained and integrated for the whole velocity region. With the proposed design optimization techniques, the total ram tube length had been reduced $19\%$ within 7 design iterations. This optimization procedure can be directly applied to the multi-stage, multi-premixture ram accelerator design optimization problems.

• Journal of the Korea Institute of Military Science and Technology
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• v.14 no.4
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• pp.639-647
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• 2011

In this paper, we have designed the Anti-Aircraft Artillery(AAA) model for the surface-to-air virtual engagement. The AAA model for the virtual combat simulation needs to detect the present target and estimate the target flight trajectory to find the aiming point. To find collision point of projectile fired from the artillery with the moving air target, we have presented the estimating technique for artillery aiming point. And we have analyzed the target probability of kill using Calton Hit function. Anti-air threat envelops are presented when the target velocity, position and the arrangement of four AAA are varying. Then we have compared the analyzed result using developed model with AEM model of MSA program.

• Journal of the Korean Society of Propulsion Engineers
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• v.12 no.5
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• pp.60-66
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• 2008

Each weapon system's muzzle velocity can be used as basic data for operating accurate automatic firing control system. Even among the same kind of ammunition, despite taking into consideration various battlefield parameters, irregular performance causes difficulties in obtaining accurate muzzle velocity data. In this study, pressure in the gun barrel was measured, the experimental relationship between chamber pressure and the projectile's base pressure was found, and a method of obtaining muzzle velocity was researched. Through this method, data regarding muzzle velocity is offered that corrects irregular performance.

• Pediatric Gastroenterology, Hepatology & Nutrition
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• v.17 no.3
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• pp.196-200
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• 2014

Co-existing pyloric submucosal masses with hypertrophic pyloric stenosis (HPS) are very rare and treating these lesions is always a problem. A 20-day-old boy presented with recurrent episodes of projectile non-bilious vomiting lasting for 5 days. HPS was suspected due to the presenting age and the symptoms. The sonography demonstrated not only circumferential wall thickening of the pylorus, but also a pyloric submucosal mass. At laparotomy, a 0.8 cm sized pyloric submucosal mass was identified along with a hypertrophied pylorus. Pyloric excision was performed due to the possibility of sustaining the symptoms and malignancy. The pathological report of the submucosal mass was ectopic pancreas. Coexisting pyloric lesions can be diagnosed along with HPS, and surgical excision, not just pyloromyotomy, should be considered in these circumstances. To the best of our knowledge, this is the first case report of pyloric ectopic pancreas and HPS to be diagnosed concurrently.

• Proceedings of the Korean Vacuum Society Conference
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• 1994.06a
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• pp.92-92
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• 1994

Relative intensities of photons emitted from tilted carbon foils have been measured in the wavelength region 300800 nm by 0,6-2,4 MeV $H^{+}\;and\;He^{+}$ ion impacts, Ions were directed onto target surfaces at tilt angles with respect to the sllrface normal, Experimental results support the model that the observed continuum radiation is emitted from the exited carbon foil itself. At each incident projectile energy, the photon intensities of continuum spectra for tilted carbon foi Is were compatred to the stoppi ng powers of carbon for $H^{+}\;and\;He^{+}$ ions, It was found that the photon emission intensity for $H^{+}$ ion is linearly proportional to the stopping power, whereas that for $He^{+}$ ions is proportional to a higher power of the stopping power, and that this tendency increases wi th decreasing velocity of the projectiIes[1, 2].[1, 2].

• Pediatric Gastroenterology, Hepatology & Nutrition
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• v.2 no.1
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• pp.99-103
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• 1999

Duodenal web is an uncommon lesion that infrequently cause partial or complete intestinal obstruction. If the duonenal web is incomplete and only partially obstructs the duodenal lumen, the onset of symptoms may be delayed for years, and obstructive symptoms will be only minimal and intermittent. Congenital duodenal obstruction is occasionally associated with intestinal malrotation. We experienced a case of duodenal web associated with intestinal malrotation in a 9-year-old girl who had been suffered from intermittent projectile vomiting since birth without failure to thrive. The diagnosis was made by UGI series & abdominal CT. Patient remained asymptomatic after operation.

• Advances in pediatric surgery
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• v.8 no.1
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• pp.23-27
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• 2002

Infantile hypertrophic pyloric stenosis (IHPS) a common childhood disorders characterized by nonbilious projectile vomiting, an olive shaped mass in the right upper quadrant of the abdomen and visible gastric peristaltic wave in the upper abdomen. Its etiology and pathogenesis are not clear but abnormal nerve distribution of the pylorus has been $postulated^{2-6}$. We performed immunocytochemical staning to the pyloric muscle from 10 IHPS and 3 controls patients, utilizing specific monoclonal antibody to NCAM(neural cell adhesion molecule). In IHPS patients, the number of NCAM protein immunoreactive nerve fibers were less than that in normal subjects. Auerbach myenteric plexuse was well developed and interbundle nerve plexuse was present but nerve fibers supplying individual muscle cells in smooth muscle bundles were poorly developed. These results indicate reduction of innervation in smooth muscles in IHPS patients that possibly contributes to the pathogenesis of IHPS.

• Advances in Computational Design
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• v.1 no.2
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• pp.139-154
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• 2016

The usage of sandwich structure is extensively increasing in lightweight protective structures due to its low density and other useful properties. Sandwich panels made of metal sheets with unfilled cellular cores are found to exhibit lower deflections by comparing to an equivalent monolithic plate of same metal and similar mass per unit density. However, the process of localized impact on solid structures involving plastic deformation, high strain rates, temperature effect, material erosion, etc. does not hold effectively as that of monolithic plate. In present work, the applications of the sandwich plate with corrugated core have been extended to develop optimized lightweight armour using foam as medium of its core by explicit finite element analysis (FEA). The mechanisms of hardened steel projectile penetration of aluminum corrugated sandwich panels filled with foams have been numerically investigated by finite element analysis (FEA). A comparative study is done for the triangular corrugated sandwich plate filled with polymeric foam and metallic foam with different densities in order to achieve the optimum penetration resistance to ballistic impact. Corrugated sandwich plates filled with metallic foams are found to be superior when compared to the polymeric one. The optimized results are then compared with that of equivalent solid and unfilled cores structure to observe the effectiveness of foam-filled corrugated sandwich plate which provides an effective resistance to ballistic response. The novel structure can be the alternative to solid aluminum plate in the applications of light weight protection system.

• Korean Journal of Materials Research
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• v.27 no.7
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• pp.359-363
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• 2017

The resistance of metallic materials to ballistic penetration generally depends on a number of parameters related to projectile, impact, and armor plate. Recently, armor materials have been required to have various properties such as hardness, strength, and impact toughness in order to maintain an excellent ballistic resistance even after impact. In the present study, the influence of tempering on the microstructure and mechanical properties of an ARMOX 500T armor steel plate was investigated and then compared with those of S45C and SCM440 steels. As the tempering temperature increased, the hardness and strength gradually decreased, whereas the ductility and impact toughness clearly increased because the hardness, tensile, and impact properties were affected by the microstructural evolution and precipitation occurring during tempering. On the other hand, temper embrittlement appeared at tempering temperatures of 300 to $400^{\circ}C$ for the impact specimens tested at low temperature.