• Journal of Biomedical Engineering Research
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• v.22 no.4
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• pp.321-330
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• 2001

In this paper, we propose a new synthetic aperture focusing scheme for improving the lateral resolution which is one of the most important factors determining the quality of ultrasound imaging. The proposed scheme enables full round-trip dynamic focusing with approximately limited property. This properties are obtained through transmitting plane waves of which the traveling angle varies with the receive subaperture position, as opposed to stepping the spherical wave source across an array in other synthetic aperture focusing schemes, and employing dynamic focusing in receive. In this paper, the properties of the proposed scheme is analyzed in which a hypothetical infinite line source is used to transmit the plane waves and verified through computer simulation results. Also, we show that the proposed scheme is realizable with an array transducer with a finite aperture size. In summary, it is shown through comparison between the field contours of the proposed scheme and the conventional scheme that the proposed scheme can improve greatly the lateral resolution of ultrasound imaging.

• Korean Journal of Veterinary Service
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• v.15 no.1
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• pp.67-80
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• 1992

Avian reoviruses have been implicated in respiratory disease enteric conditions including Cloacal pasting in young thicks, pericarditis, hydropericardium, anaemia with swollen spleen and liver and petechiation of skeletal muscle and viral arthritis. This study was conducted to examine properties of reovirus field 3 strains isolated from affected broiler from several farms. An infectious agent was isolated from leg tendons and intestine of broiler with clinical tenosynovitis. The agent grew well on the chicken embryo kideny cells(CEK). One of them produced cytopathic effects(CPE) of round type and formed intranuclear inclusions, and the other was characterized by CPE of syncytical type and cytoplasmic inclusion. The properties and serological classification of field strains were examined by hemagglutin test, virus neutralization test, agar gel precipitin, electropherotype. They showed no hemagglutination reactions and not well neutralization and to possess common antigens detectable by AGP test. RNA electropherotype presented 10 segment band as the previous report. These data suggest that the field strains and standard strains (1133, 1733) may be the same group.

• Journal of the Korean Ceramic Society
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• v.36 no.4
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• pp.366-371
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• 1999

The effect of VC addition on the microstructural evolution of Fe-TiC cermet has been investigated. The microstructures of the Fe-TiC varied with the amount of VC addition. The addition of 1wt% VC enhanced the instability of liquid-solid interface ; the dissolving interface showed round shape instead of facetted one which was ascribed to the increase of lattice mismatch between TiC and solid-solution carbide. in the speci-men with 10wt% VC the new set of solid-solution carbide grains of uniform and small size was formed in-side coarse TiC particles by diffusion induced recrystallizatin (DIR). With increasing the heat-treatment time fine recrystallized grains were dispersed homogeneously in the matrix and resulted in the increase in fracture strength.

• Bulletin of the Society of Naval Architects of Korea
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• v.18 no.4
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• pp.13-20
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• 1981

The hydrodynamic added mass of two dimensional cylinders oscillating vertically at high frequencies in the free surface is of interest to ship vibration problems. Conformal transformation is one of the methods commonly in use for computing the inertia coefficient. Especially, Schwarz-Christoffel transformation has been employed to evaluate the inertia coefficient for the cylinders of straight frames and chines. In this paper, the inertia coefficient for the cylinders with round corners in vertical oscillation at high frequencies are evaluated by employing the Schwarz-Christoffel transformation for the concave corner. The results of calculation by employing the Schwarz-Christoffel transformation are found to be well within the expected range of values compared to Lewis form and the results obtained by source distribution method.

• International Journal of Control, Automation, and Systems
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• v.5 no.3
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• pp.317-323
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• 2007

Quality of Service (QoS) in the Internet depends on queuing and sophisticated scheduling in routers. In this paper, we address the issue of managing traffic flows with different priorities. In our reference model, incoming packets are first classified based on their priority, placed into different queues with different capacities, and then multiplexed onto one router link. The fuzzy nature of the information on Internet traffic makes this problem particularly suited to fuzzy methodologies. We propose a new solution that employs a fuzzy inference system to dynamically and efficiently schedule these priority queues. The fuzzy rules are derived to minimize the selected Lyapunov function. Simulation experiments show that the proposed fuzzy scheduling algorithm outperforms the popular Weighted Round Robin (WRR) queue scheduling mechanism.

• Proceedings of the IEEK Conference
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• 2002.06a
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• pp.191-194
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• 2002

We analyzed radiation characteristics of dipole antenna in a lossy 9round with conducting object located above ground. Electric field integral equation is used to solve the problem. In this integral equation, GPOF(Generalized Pencil of Function) method is applied to derive the closed form of the electric field due to a current source. Surface current on a conductor is expanded with a well-known vector triangle basis function. The singular integration of a triangle patch is transformed to the non-singular integration by Duffy's method. This transformed non-singular integration is easily calculated by using one-dimensional Gaussian quadrature rule, instead of usual closed form evaluation.

• Journal of the Korean Institute of Navigation
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• v.23 no.4
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• pp.77-88
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• 1999

Container terminal productivity is a critical factor for both the terminal operator and liner companies. For the former it is a determinant factor of the competitiveness and profit of terminal, and for the later it is one that determines ships' tern round time and hence ships' operation costs. The concept and measures of productivity are however not well defined and unified throughout terminals in the world. This paper therefore deals with the empirical study on the evaluation of container terminal productivity. It first clarifies the concept of terminal productivity, and secondly based on the actual data on container terminals in and outside Korea, productivity is evaluated and compared. Finally, problems hampered efficient operation of Korean terminals are derived, and several comments are suggested for solving them.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2006.05a
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• pp.274-277
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• 2006

This paper describes a lighting warning system (LWS) which consists of a corona needle electrode, a low noise differential amplifier, an A/D converter, an one-chip microprocessor, a LCD and alarm devices. The corona needle electrode is used to measure electric field intensity caused by thunderclouds on the ground level. To evaluate the sensitivity of the LWS, calibration experiment was carried out using a round-shape parallel plate electrode system. The theoretical and experimental results show that the LWS can measure electric field intensity over 2 [kV/m].

• Journal of Veterinary Clinics
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• v.19 no.3
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• pp.360-362
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• 2002

A 9-year-old male Maltese with foamy nasal discharge, respiratory distress, and sneezing followed by epistaxis was presented to the Veterinary Medical Teaching Hospital of Seoul National University. Radiography showed no significant findings from an open mouth view. Rhinoscopy also did not find any remarkable lesions in the nasal cavity. But when vigorously swabbing the nasal cavity, numerous cells having round nuclei, coarse reticular chromatin, one large nucleolus and distinct cytoplasmic vacuoles, which is typical for canine transmissible venereal tumor cells were collected. We thoroughly searched for any primary transmissible venereal tumor at the other areas of the body other than the nasal cavity, but found none. The patient responded well to vincristine, and the clinical signs resolved with no respiratory distress, sneezing or epistaxis.

• Korean Journal of Veterinary Service
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• v.16 no.1
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• pp.11-19
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• 1993

This experiment was carried out to detect the residues of sulfonamides in raw milk. Raw milks which does not contain sulfonamides was collected from one of the farm and fortified with 5 sulfonamides (sulfamerazine, sulfamethazine, sulfamonomethoxine, sulfadimethoxine, sulfaqinoxaline). The sulfonamides in the fortified sample were extracted and detected by High Performance Liquid Chromatography. UV /vis detector was used in this experiment. The results obtained were summarized as follows : 1. Chloroform was good as a extracting solution. 2. 15.5% methanol in PDP as a mobile phase solution was best detective condition for SMR, SMT, SMM. But for SDM and SQN the best condition was 23% methanol. 3. The detectable limits of SMR, SMT, SMM were 2ppb. but SDM and SQN were 20ppb because of delayed retention time and relatively low recovery rate. 4. The peaks of SMR, SMT, SMM and SDM were erected at baseline and the apexes were sharp but SQN was round shape.