• Journal of the Korean earth science society
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• v.23 no.4
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• pp.357-368
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• 2002

In this study we have tried to explain the barrel-shaped morphology for young supernova remnants considering the dynamical effects of the ejecta. We consider the magnetic field amplification resulting from the Rayleigh-Taylor instability near the contact discontinuity. We can generate the synthetic radio image assuming the cosmic-ray pressure and calculate the azimuthal intensity ratio (A) to enable a quantitative comparison with observations. The postshock magnetic field are amplified by shearing, stretching, and compressing at the R-T finger boundary. The evolution of the instability strongly depends on the deceleration of the ejecta and the evolutionary stage of the remnant. the strength of the magnetic field increases in the initial phase and decreases after the reverse shock passes the constant density region of the ejecta. However, some memory of the earlier phases of amplification is retained in the interior even when the outer regions turn into a blast wave. The ratio of the averaged magnetic field strength at the equator to the one at the pole in the turbulent region can amount to 7.5 at the peak. The magnetic field amplification can make the large azimuthal intensity ratio (A=15). The magnitude of the amplification is sensitive to numerical resolution. This mens the magnetic field amplification can explain the barrel-shaped morphology of young supernova remnant without the dependence of the efficiency of the cosmic-ray acceleration on the magnetic field configuration. In order for this mechanism to be effective, the surrounding magnetic field must be well-ordered. The small number of barrel-shaped remnants may indicate that this condition rarely occurs.

• Investigative Magnetic Resonance Imaging
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• v.2 no.1
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• pp.113-119
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• 1998

Purpose : Because adenocarcinomas of the uterine cervix have lower 5-year survival rate than squamous cell carcinomas due to early lymph node metastasis and local extension, scrutiny of lymph node metastasis and local extension by radiologic examination is necessary in case of clinically diagnosed or suspected adenocarcinomas. The purpose of this study is to evaluate whether there are specific findings of these tumors, compared with squamous cell carcinomas, through the analysis of magnetic resonance (MR) imaging findings. Materials and Methods : Of 21 pathologically proven cervical adenocarcinomas, MR imaging findings of 18 tumors (histologic staging : two Ib, four IIa, two IIb, one IIIa, and one IIIb) were retrospectively analyzed and compared with those of 40 wquamous cell carcinoma in consecutive patients as a control group. T1-wetighted and fast spin echo T2-weighted images were obtained on the axial and sagittal planes, using a 1.5-T MR scanner. The largest diameter, location, signal intensity and degree of contrast enhancement contour, shape and longitudinal extent of the tumor and associated findings on MR image were analyzed. Results : The largest diameters of cervical adenocarcinomas ranged from 0.8 to 4.1 cm(mean, 2.2 cm). Of 18 adenocarcinomas, nine were of endocervical type. All adenocarcinomas were isointense to surrounding cervical stroma on T1-weighted images and hyperintense(homogeneous in ten, inhomogeneous in eight) on fast spin echo T2-weighted images. Adenocarcinomas enhanced on contrast study in all patients (homogeneous in six, inhomogeneous in 12 with hyperintese enhnacing rim in two). Eight adenocarcinomas had smooth contours and ten had irregular ones. The shape of adenocarcinoma was irregular in eight patients, barrel shape in six, papillary/polypod in three, and nodular in one. All adenocarcinomas involved lower half of the uterine cervix and six tumors extended up to the upper half. Pelvic lymph nodes of more than 1.5cm in diameter in two adenocarcinomas pateints and no detectable small pelvic lymph nodes on MR imaging in one patient were pathologically positive. Hydrometra was associated in two adenocarcinomas patients, and hematometra in one patient. Compared with squamous cell carcinomas, more frequent MR findings of endocervical type and barrel shape in cervical adenocarcinomas were statistically significant. Conclusion : Cervical adenocarcinomas had more frequent MR findings of endocervical type and barrel shape, compared with wquamous cell carcinomas. Adenocarcinoma of the uterine cervix may be suspected on MR imaging, when a cervical carcinoma is of barrel shape along the endocervical canal and tends to involve lymth nodes in earlier stages.

• New & Renewable Energy
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• v.4 no.2
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• pp.52-60
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• 2008

More people have become interested in hybrid vehicles - which have been heralded as environmentally friendly automobiles - recently as the opening of domestic hybrid vehicle market draws near. Since gasoline, diesel and LPG hybrid vehicles will be produced, a need exists to conduct economic feasibility study of each vehicle type. This research analyzed projected benefits of these hybrid vehicles based on the 1600cc model. There are two categories of benefits: 1) reduced fuel costs for the owners of the vehicles; and 2) reduced environmental pollution cost. We conducted a sensitivity analysis and estimated the domestic consumer fuel costs based on the international oil prices of 100USD, 150USD, and 200USD per barrel. The analysis showed savings of 2 to 4 million Won in fuel cost and 1 to 2 million Won in environmental pollution cost; therefore, the hybrid vehicles are not economically feasible if they are between 3 to 5 million Won more expensive than the conventional internal combustion engine vehicles.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 1997.04a
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• pp.75-84
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• 1997

Based upon the results of numerical calculation. empirical scaling equations were made for supersonic under-expanded jets in both axisymmetric and two dimensional flows. The objective of the present study is to obtain a straightforward method that can predict the under-expanded supersonic jets issuing from various kinds of nozzles. The present empirical equations were agreed with the calculation results of total variation diminishing difference scheme. The supersonic under-expanded jets operating with a given pressure ratio could be well predicted by the present scaling equations.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• v.y2005m4
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• pp.386-393
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• 2005

The objective of the present study is to develop a new type of the Ballistic range, called 'two-stage light gas gun'. A computational work has been performed to investigate the aerodynamics of a projectile which is launched from the two-stage light gas gun. A moving coordinate method for a multi-domain technique is employed to simulate unsteady projectile flows with a moving boundary. The effect of a virtual mass is added to the axisymmetric unsteady Euler equation systems. The computed results reasonably capture the major flow characteristics which are generated in launching the projectile supersonically, such as the interaction between the shock wave and the blast wave, the interaction between the vortical flow and the barrel shock, and the steady under-expanded jet. The present computational results properly predict the velocity, acceleration, and drag histories of the projectile.

• Proceedings of the Korean Society of Sericultural Science Conference
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• 2003.10a
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• pp.71-74
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• 2003

Superoxide dismutase (SOD), one of the essential element of the antioxidant defense system, mainly removes $O^{-10}$ $_2$ and also prevents $O^{-10}$ $_2$ mediated reduction of iron and subsequent OH$^{-10}$ generation, which is highly toxic to the organism. Of these SOD enzymes, Cu, Zn-containing SOD (SODI) is an important component of the antioxidant defense system in eucaryotic cells. The SODI enzyme binds one copper and one zinc ion and displays the Greek Key $\beta$-barrel fuld. (omitted)

• Journal of the Korean Institute of Telematics and Electronics S
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• v.35S no.2
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• pp.50-57
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• 1998

In this paper, we propoe a log N-stage ATM concentator. ATM concentrator is used in the ATM access network to concentrate the traffic offered at UNI, so that high utilization of the newtork rewources is achieved. The concetrator may be used as a construction block in the design of ATM switch. We define abasic element, named equalizer, and decribe its function and theory to construct an efficient concentrator using the element. In addition, a control scheme to enhance the concentrator to a superconcentrator is presented, which enables the concentration to start from an arbitrary output. This scheme makes it possible to construct an efficient ditributior or a barrel shifter which are often used in ATM switch and other application. The proposed concentrator has a low hardware complexity of O(N log N), thus it is economical to implement. Also, the time complexity of proposed concentrator for determining the rouging is O(N log N), which is faster than that of the existing ones.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.14 no.6
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• pp.69-76
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• 2015

This study investigates the thermal efficiency and the efficiency of heat transfer through thermal analysis when the same heat is applied to a mortar frame by firing with various configurations of mortar. As the inside diameter of the mortar increases, the additional material must be reinforced. In comparison with the extent of getting cold due to models, a mortar with the strut under the gun barrel becomes cooler than one with no strut. The thermal deformation at firing becomes different. According to the configuration of mortar and its inside diameter, the extent of getting cold becomes different. This study result can be effectively applied for improving the efficiency of the heat transfer of mortar.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.21 no.4
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• pp.593-600
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• 2012

Thixomolding of Mg-alloy is a semi-solid injection molding process utilizing thixotropic phenomenon. Using this process, higher strength, thinner wall section and tighter tolerance without porosity are obtained. It has been applied for production of near-net-shape magnesium component. To design optimal thixomolding process of Mg-alloy part, molding conditions such as slurry temperature, mold temperature and injection time should be determined properly. Selection of these parameters has been dependent upon engineers' experience and intuitiveness. In this paper, to improve mechanical properties of the thixomolded product, optimal selection of process variables such as injection velocity, barrel temperature and die temperature in the process has been studied through microstructural analysis and Taguchi method. Performance of the process is verified through experiments.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.1668-1671
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• 2005

Vulcanized natural rubber was pulverized using a single screw extruder in a non-cryogenic Solid Shear Extrusion process where rubber granulates were subjected to high compressive and shear stresses. The producted particles had diameters ranging from 40 to 1200$\{mu}m$. A principle used in this paper was developed in Russia. The development method for producing a polymeric material powder consists in compressing said material by shearing the material during a pressure increase and cooling. Consecutive breakdown is carried out by shearing the material during the pressure decrease and cooling.