• Journal of Broadcast Engineering
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• v.6 no.3
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• pp.246-259
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• 2001

Due to recent rapid deployment of Internet streaming service and digital broadcasting service, the issue of how to efficiently support streaming workload in so called "Internet Home Appliance" receives prime interests from industry as well as academia. The underlying dilemma is that it may not be feasible to put cutting edge CPU, boards, disks and other peripherals into that type of device. The primary reason is its cost. Usually, Internet Home Appliances has its dedicated usage, e.g. Internet Radio, and thus it does not require high-end CPU nor high-end Va subsystem. The same reasoning applies to I/O subsystem. In Internet Home Appliances dedicated to handle compressed moving picture, it is not equipped with high end SCSI disk with fast rotational speed. Thus, it is mandatory to devise elaborate software algorithm to exploit the available hardware resources and maximize the efficiency of the system. This paper presents our experiences in the design and implementation of a new multimedia file system which can efficiently deliver the required disk bandwidth for a periodic I/O workload. We have implemented the file system on the Linux operating system, and examined itsperformance under streaming I/O workload. The results of the study show that the proposed file system exhibits superior performance than the Linux Ext2 file system under streaming I/O workload. The result of this work not only contribute to advance the state f art file system technology for multimedia streaming but also put forth the software which is readily available and can be deployed. deployed.

• Journal of Astronomy and Space Sciences
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• v.21 no.1
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• pp.11-28
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• 2004

To better understand how high-latitude electric fields influence thermospheric dynamics, winds in the high-latitude lower thermosphere are studied by using the Thermosphere-ionosphere Electrodynamics General Circulation Model developed by the National Conte. for Atmospheric Research (NCAR-TIEGCM). The model is run for the conditions of 1992-1993 southern summer. The association of the model results with the interplanetary magnetic field(IMF) is also examined to determine the influences of the IMF-dependent ionospheric convection on the winds. The wind patterns show good agreement with the WINDII observations, although the model wind speeds are generally weaker than the observations. It is confirmed that the influences of high-latitude ionospheric convection on summertime thermospheric winds are seen down to 105 km. The difference wind, the difference between the winds for IMF$\neq$O and IMF=0, during negative IMF $B_y$ shows a strong anticyclonic vortex while during positive IMF $B_y$ a strong cyclonic vortex down to 105 km. For positive IMF $B_z$ the difference winds are largely confined to the polar cap, while for negative IMF B, they extend down to subauroral latitudes. The IMF $B_z$ -dependent diurnal wind component is strongly correlated with the corresponding component of ionospheric convection velocity down to 108 km and is largely rotational. The influence of IMF by on the lower thermospheric summertime zonal-mean zonal wind is substantial at high latitudes, with maximum wind speeds being $60\;ms^-1$ at 130 km around $77^{\circ}$ magnetic latitude.

• Journal of KIISE:Databases
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• v.36 no.2
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• pp.73-83
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• 2009

In this paper we propose an object similarity matching method based on shape characteristics of an object in an image. The proposed method extracts edge points from edges of objects and generates a log polar histogram with respect to each edge point to represent the relative placement of extracted points. It performs the matching in such a way that it compares polar histograms of two edge points sequentially along with edges of objects, and uses a well-known k-NN(nearest neighbor) approach to retrieve similar objects from a database. To verify the proposed method, we've compared it to an existing Shape-Context method. Experimental results reveal that our method is more accurate in object matching than the existing method, showing that when k=5, the precision of our method is 0.75-0.90 while that of the existing one is 0.37, and when k=10, the precision of our method is 0.61-0.80 while that of the existing one is 0.31. In the experiment of rotational transformation, our method is also more robust compared to the existing one, showing that the precision of our method is 0.69 while that of the existing one is 0.30.

• Journal of radiological science and technology
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• v.33 no.4
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• pp.379-386
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• 2010

This study evaluated the motion of tumors during the entire period of therapy and the accuracy of radiosurgery among forty eight lung tumor patients who were underwent radiosurgery using the CyberKnife Synchrony Respiratory Tracking System. The motion of lung tumor was measured by the coordinates of a gold acupuncture needle inserted into the tumor or the area around the tumor using the CyberKnife image guided system. Then the accuracy of radiosurgery was evaluated based on the error of correlation computed with the motion tracking system. The lung tumor motion is Cranio-Caudal direction by an average of $2.63{\pm}1.87\;mm$, moved left-right direction by $1.13{\pm}0.71\;mm$, and anterior-posterior direction by $1.74{\pm}1.16\;mm$. The degree of rotational movement was $1.66{\pm}1.66^{\circ}$ on X axis, $1.20{\pm}0.97^{\circ}$ on Y axis, and $1.18{\pm}0.73^{\circ}$ on Z axis. The vector of translation movement was measured to be $3.78{\pm}2.00\;mm$ on the average. The results show that directions of Cranio-Caudal(p < 0.001), anterior-posterior direction(p < 0.029), and three dimensional vector value(p < 0.002) showed statistical significance, because the lower side of tumor showed more intensive movement compared to the upper side of tumor. The radiosurgery was carried out by compensating the motion of tumor after accurate investigation of the correlation error with the average of $0.95{\pm}0.62\;mm$ during the lung tumor radiosurgery with the CyberKnife Synchrony Respiratory Tracking System.

• Land and Housing Review
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• v.4 no.3
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• pp.271-277
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• 2013

The BNWF (Beam on Nonlinear Winkler Foundation) model is one of the simplest idealizations for a pile embedded in soil as it ignores the continuity of the soil. This method is difficult to model the behavior of pile group foundation subjected to lateral loading. The limitation can be overcome with the utilization of the finite element method (FEM) or finite different method (FDM) to represent a pile element embedded in a soil medium. Both the ground and piles are modeled with soild elements. The solid elements, which do not have rotational degree of freedom, is not appropriate for modeling piles. It can be overcome by substantially increasing the number of elements, which can be prohibitive for 3D modeling. This paper used the beam element and rigid link incorporated in the OpenSees to model the pile. The accuracy of the model is validated through comparison with lateral load test and BNWF analysis. It is shown that the method can capture the measured behavior accurately. It is therefore recommended to be used in group pile analyses.

• Archives of Reconstructive Microsurgery
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• v.7 no.1
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• pp.62-67
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• 1998

The gracilis muscle is well suited to small and medium-sized soft tissue defects that cannot be adequately handled by simple rotational flaps and it will conform well to irregular contours, can be split longitudinally at both ends to allow cavities and awkwardly shaped spaces and can be transferred in part or in whole. The gracilis muscle used as a free muscle or musculocutaneous flap is small with a long, narrow contour and its vascular pedicle is a terminal branch of the medial femoral circumflex artery and vein. The aims of soft tissue reconstruction are to cover soft tissue defects, to clear up infection and to prepare for further surgical procedures. Authors have performed 12 gracilis muscle flaps in the lower extremities at Chonbuk National University Hospital from June 1994 through March 1998. The results were as follows. 1. 11 cases of 12(91.7%) were sustained from the crushing injury and secondary complications from the traffic accident. 2. The microsurgical anastomosis of one artery and two veins have performed in 6 cases(50%) of 12 and 11(91.7%) cases of 12 were successful at the third postoperative week and in the final result. 3. Gracilis muscle flap is the infetion-resistant and aesthetically acceptable performed in the lower leg 1/3 and the foot.

• Korean journal of food and cookery science
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• v.22 no.5 s.95
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• pp.666-680
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• 2006

To obtain basic data for the utilization of saltwort (Salicornia herbacea L.) as a functional ingredient in steamed foam cake, the optimum component ratios for major raw ingredients (saltwort, salt, and wheat flour) as independent variables that affect the product quality were scientifically determined using RSM (response surface methodology) technique. A three-factor and five-level rotational central composite design was used for treatment arrangement. The complete design consisted of 16 experimental points. The three independent variables selected for the RSM experiment were amounts of saltwort (X$_1$, 5${\sim}$25 g), salt (X$_2$, 0${\sim}$10 g), and wheat flour (X$_3$, 470${\sim}$530 g). The optimum responses in specific gravity of the batter and volume, color, texture, and sensory evaluation result of the cake were obtained. The specific gravity and viscosity of the batter at p<0.01 was verified from the regression curve. The characteristic of the batter was influenced by all independent variables, but was extremely dependent on the amount of saltwort ordinary points of the surface responses from the batter formed the minimum points for specific gravities of the batter while viscosities of the batter appeared with the saddle points. Analysis of the response indicated that the amount of saltwort was the most influential factor over the physical properties of the cake, among the dependent variables. Ordinary points of the surface responses from the cake formed the maximum points for loaf volume, hardness gumminess, and chewiness, while Hunter colorimetric parameters appeared with the saddle points. The result indicated that level of the saltwort deviating more or less from the optimal amount decreased the volume and increased the specific gravity with less tender product. Ordinary points of the surface responses of the sensory evaluation scores from the cake formed the maximum points for appearance, flavor, softness, and overall acceptability, while color values appeared with the saddle points. The result also indicated that the level of the saltwort deviating more or less from the optimal amount reduced the preference for the product. Integration of the optimum responses common to all dependent variables that overlapped all the contour maps finally indicated that the combination of 8.3${\sim}$13.8 g saltwort, 2.5${\sim}$6.6 g salt, and 486.5${\sim}$511.5 g wheat flour under the selected preparation recipe optimized the physical and sensory properties in the teamed foam cakes. Practical preparation of the product with median amounts of the ingredients, i.e., 11.0 g saltwort, 4.6 g salt, and 499.0 g wheat flour resulted in similar qualities to the predicted responses. In conclusion, these study results indicated that preparation of steamed foam cake with added saltwort ingredient could potentially produce a more nutritious product with less salt. Further research is required to acquire the optimum levels for sub-ingredients to improve the product quality.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.6
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• pp.703-709
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• 2017

Korea Utility Helicopter(KUH) is a project to replace the aging helicopter presently being operated by the military with a domestic helicopter. The auxiliary power unit is a device that supplies emergency power to the system by an alternator installed when the main generator fails and the start motor converts the electrical energy of the battery into mechanical rotational energy to rotate the auxiliary power unit engine. With continuing power and operation, defects of the starting motor were found and improvements were carried out to solve it. In the failure mode analysis, the causes of possible defects were classified into 5 categories. Analysis of the 5 factors revealed that the main cause of defects is mechanical wear, which was found to be related to spring pressure. 250 tests were conducted through the theoretically determined pressure and regression analysis was performed with 4 sampling.The results showed that pressure was related to wear rate. In conclusion, early wear and breakage due to wear can be controlled through spring force and test showed the prediction of wear and the validity of the result were confirmed.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.10
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• pp.280-288
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• 2016

This study proposes improved welding tools for magnesium alloys. Two types of tools were used for friction stir welding (FSW). The effect of the welding tools on the FSW joints was investigated with a fixed welding speed of 200mm/min and various rotation speeds of 400 to 800 rpm. After FSW, the joints were cross-sectioned perpendicular to the welding direction to investigate the defects. A tensile test and Vickers hardness test were conducted to identity the mechanical properties of the joints. Defects were observed when the rotation speed was 400 rpm, regardless of the welding tool, and the amount of defects tended to decrease with increases in rotational speed. Defect-free welds were obtained when the rotation speed was 800 rpm. The best weld quality was acquired using the C type welding tool. The rotation speed of 800 rpm and welding speed of 200 mm/min produced the best joining properties. The ultimate tensile strength, yield strength, and elongation of the welded region were 90.0%, 69.1%, and 83.2% those of the base metal, respectively.

• Journal of KIISE:Computing Practices and Letters
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• v.16 no.1
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• pp.1-10
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• 2010

Recently heterogeneous storage system such as hybrid hard disk drive (H-HDD) combining flash memory and magnetic disk is launched, according as the read performance of NAND flash memory is enhanced as similar to that of hard disk drive (HDD) and the power consumption of NAND flash memory is reduced less than that of HDD. However, the read and write operations of NAND flash memory are slower than those of rotational disk. Besides, serious overheads are incurred on CPU and main memory in the case that intensive write requests to flash memory are repeatedly occurred. In this paper, we propose the Least Frequently Used-Hot scheme that replaces the data blocks whose reference frequency of read operation is low and update frequency of write operation is high, and the data flushing scheme that rearranges the data blocks into the multi-zone of the rotation disk. Experimental results show that the execution time of the proposed method is 38% faster than those of conventional LRU and LFU block replacement schemes in I/O performance aspect and the proposed method increases the life span of Non-Volatile Cache 40% higher than those of conventional LRU, LFU, FIFO block replacement schemes.