• Journal of the Korea Institute of Military Science and Technology
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• v.26 no.5
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• pp.371-383
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• 2023

Artillery gun tube experiences very high pressure according to the blast of propellant charge. Therfore, it is essential to guarantee the structural safety of the gun tube. On the other hand, weight reduction of gun tube is also a crucial design factor since the agility of artillery vehicle directly leads to its survivability. In this line of thought, this work proposed an efficient design procedure which utilizes the convex combination of breech pressure and projectile base pressure time histories. Its efficiency is verified by comparing with other procedures. Other procedures utilize different computed max pressure rather than the convex combination design pressure. Additionally, a transient analysis is carried out considering the projectile movement and the corresponding pressure distribution through the newly developed ABAQUS user-subroutine. The analysis confirms the structural safety of the lightweight gun tube designed by the proposed method.

• Journal of the Korean Society for Precision Engineering
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• v.14 no.6
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• pp.52-63
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• 1997

Non-circular gear has a good velocity ratio in high speed and heavy load without any slip, moreover, it can transmit various motion, using simpler structure than link and cam, automation mechainism. In case of designing and manufacturing non-circular gear. I suggest one of references in applying non-circular gear to industrial plant, and suitable range of application by pressure angle curvature and angle ratio

• Magazine of the Korean Society of Agricultural Engineers
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• v.17 no.4
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• pp.3991-4000
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• 1975

It is the aim of this study to investigate the influence of the factors in the sprayer nozzle for the travelling distance and to get nozzle design data in relation to the nozz1e with and without swirl plate. The factors of sprayer nozzle are composed of the spraying pressure, the helical angle of swirl plate, the helical groove depth of swirl plate, the distance of vortex chamber the slope of nozz1e cap, the curvature of nozzle cap and the hole diameter of nozz1e cap. The travelling distance and the size of sprayed particle are experimeted indoors by the factorial arrange-ment according to the 5 each level of the above factors. The results of this stupy are summarized as follows; 1. In the nozzle with swirl p1ate there were remarkable significance among factors each other, while without swirl plate were no significance. 2. The helical angle and groove depth in the nozzle with swirl plate were the highest effective factors. The effect of helical angle was very remarked in the quadratic curve with minium value. 3. The correlation betweenthe travelling distance and the sprayed particle size was no high and under 250 micron in the case with swirl plate, and there was higher correlation in the case without swirl plate. 4. The new ideal development of the swirl plate using of the most effective helical angle and groove depth will probably show the possiblities to make effective travelling distance over 8 meters and more over and to make average particle diameter under 300 micron.

• Journal of the Korean Geotechnical Society
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• v.32 no.1
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• pp.55-62
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• 2016

This study presents the numerical results of soil-water characteristic curve for sandy soil by pore network model. The Jumunjin sand is subjected to the high resolution 3D X-ray computed tomographic imaging and its pore structure is constructed by the web of pore body and pore channel. The channel radius, essential to the computation of capillary pressure, is obtained based on the skeletonization and Euclidean Distance transform. The experimentally obtained soil-water characteristic curve corroborates the numerically estimated one. The pore channel radius defined by minimum radii of pore throat results in the slightly overestimation of air entry value, while the overall evolution of capillary pressure resides in the acceptable range. The relative permeability computed by a series of suggested models runs above that obtained by pore network model at high degree of saturation.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.07a
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• pp.901-904
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• 2000

In order to investigate the effect of deposition conditions on crystallographic properties of ZnO thin films by Facing Targets Sputtering system which can deposit thin films in plasma-free situation and change the deposition conditions in wide range. The characteristics of zinc oxide thin films on power, inter targets distance, and substrate temperature were investigated by XRD(x-ray diffractometer), alpha-step (Tencor) analyses. The excellently c-axis oriented zinc oxide thin films were obtained at sputter pressure 1mTorr, sputtering current 0.4A, substrate temperature 300$^{\circ}C$, inter target distance 100mm. In these conditions, the rocking curve of zinc oxide thin films deposited on Glass was 3.9$^{\circ}$.

• Solar Energy
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• v.18 no.3
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• pp.217-228
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• 1998

The purpose of this research is to investigate the characteristics of static and total pressure distribution in the upward free water jet system impinged on a downward flat plate. The rectangular nozzle was used and its contraction and aspect ratio was five and about seven respectively. Experimental conditions considered were jet velocity, distance between nozzle and flat plate, height of supplementary water. It was founded that pressure distribution on the flat plate had the Gaussian curve when the pressure at stagnation point and impinging half width were chosen as the scaling parameters. The maximum pressure was shown at the stagnation point. The central impingement velocity decreased with the increment of distance between nozzle and flat plate, and its slop of decay was similar to that of chracteristics decay region in the three-dimensional free jet.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.10 no.1
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• pp.133-140
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• 2001

Recently, to assure the integrity of a structural components such as piping pressure vessels and thinning structure, Lamb wave inspection technique has been used in material evaluation. It is very important to select the optimal Lamb wave mode and to analyze the signal accurately because of its unique dispersion properties grnerating several modes within the speci-men. It this study, the feasibility of material evaluation applications using wavelet analysis of Lamb wave has been veir-fied experimentally. These results show as follows; 1)dispersion characteristic of each mode in dispersion curve is demon-strated that A0 mode propagating material surface is useful mode having the lest energy loss and not sensitive to surface condition. 2) it can be detected even the micro defect ($1\times2mm$) fabricated in ultrasonic probe flaw distance (290mm) to axis direction. 3) the wavelet transform which is called "time-frequency analysis" shows the Lamb wave propagation due to the change of materials characterization can be evaluated at each frequency and experimental group velocity of Lamb wave agrees quite well with that of simulated dispersion curve.ion curve.

• Transactions of the Korean Society of Mechanical Engineers
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• v.1 no.3
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• pp.125-130
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• 1977

This is a dimensionless analysis of interior ballistics for the design of gun tube. One of the characteristics of this analysis is to ues the .ETA.$_{j}$ number which means a relative quantity of virtual work to the kimetic energy of projectile at the muzzle. In order to apply the concept of virtual work, it is assumed that the projectile is moved from the beginning to the end of bore under constant pressure of the certain travel distance of projectile. The principle of the analysis is induced from the Le Duc equation, which expresses velocity as a function of projectile travel and is based on the translation of a hyperbolic curve. From this non-dimensional analysis, the optimum design parameters of pressure in the bore, velocity and acceleration of projectile can be obtained from the table of figure without computation. This method was verified by the experimental work.k.

• The KSFM Journal of Fluid Machinery
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• v.13 no.2
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• pp.48-53
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• 2010

A computerized design system of axial fan is developed for constructing 3-D blade geometry and predicting both aerodynamic performance and noise. The aerodynamic blading design of fan is conducted by blade angle distribution, camber line determination, airfoil thickness distribution and blade element stacking along spanwise distance. The internal flow and the aerodynamic performance of designed fan are predicted by the through-flow modeling technique with flow deviation and pressure loss correlations. Based on the predicted internal flow field and performance data, fan noise is predicted by two models for discrete frequency and broadband noise sources. The present predictions of the flow distribution, the performance and the noise level of actual fans are well agreed with measurement results.

• Proceedings of the KSME Conference
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• 2001.11b
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• pp.371-376
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• 2001

The operating point of a small-sized axial fan for refrigerator is strongly dependent upon the system resistance. Therefore, the turbulent flow characteristics around a small-sized axial fan may change significantly according to the operating point. This study represents three-dimensional turbulent flow characteristics around a small-sized axial fan measured at the four operating points such as $\varphi=0.1$, 0.18, 0.25 and 0.32 by using fiber-optic type LDA system. This LDA system is composed of a 5 W Argon-ion laser, two optics in back-scatter mode, three BSA's, a PC, and a three-dimensional automatic traversing system. A kind of paraffin fluid is utilized for supplying particles by means of fog generator. Mean velocity profiles downstream of a small-sized axial fan along the radial distance show that both the streamwise and the tangential components exist predominantly in downstream except $\varphi=0.1$ and have a maximum value at the radial distance ratio of about 0.8, but the radial component, which its velocity is relatively small, is acting role that only turns flow direction to the outside or the central part of axial fan. Moreover, all of the velocity components downstream at $\varphi=0.1$ show much smaller than those upstream due to the static pressure rise at the low-flowrate region.