• Journal of the Korean Society of Radiology
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• v.6 no.6
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• pp.465-471
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• 2012

In this study, three dimensional X-ray dose distribution from dental X-ray generator system was measured by ALOKA PDM-117 dosimeter. The X-ray dose distribution will be change with XCP-DS FIT in oral shot, because the distance between X-ray generator and the dosimeter. The X-ray dose change affects on patient exposure and radiograph image quality. Therefore, it is important to obtain relation between the X-ray dose and the distance. The X-ray dose at the central position was decreased with increasing the distance. Furthermore, the dose at the edge of the X-ray flux was increased with increasing the distance. The increased dose affects on the patient radiation exposure. The present results will provide for good dental radiograph image and reducing radiation over-exposure on patient.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.5 no.2
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• pp.146-156
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• 2000

Zonation pattern of macro-invertebrate community structure was examined from Okjukpo sandy beach, Taechongdo, Korea. Macrofauna were collected in June 1998 using a can corer from ten stations along one transect. Mean grain size ranged from 1.97 to 2.23${\phi}$ and sediment organic contents ranged from 0.52 to 1.02%. A total of benthic macro-invertebrates comprised 25 species, providing 10,705 individuals and 89.13 g wet weight in biomass. Peracaridean crustaceans such as amphipods and isopods are the most prominant components in this exposed sandy beach. The dominant species were Eohaustorius setulosus (33%), Excirolana chiltoni (26%), Haustorioides koreanus (12%), Platorchestia crassicornis (8%), and Cycladicama cumingii (6%). The zonation patterns by these animals were very similar to those noted by Dahl(1952) and Jo(1990). They are divided into three faunal zones: 1) subterrestrial fringe dominated by a talitrid amphipod Platorchestia crassicornis, 2) midlittoral zone by a cirolanid isopod Excirolana chiltoni, 3) sublittoral fringe by more diverse amphipods communities.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.31 no.5
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• pp.665-672
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• 1998

Feeding habits of Conger myiaster collected from the eelgrass bed in Kwangyang Bay from January 1994 to December 1994 were studied. C. myiaster was a carnivore which consumed mainly fishes, shrimps and crabs. Its diets included small quantities of amphipods, gastropods, cephalopods, polychaetes, mysids, cumaceans and isopods. It showed ontogenetic changes in feeding habits. Small indinviduals preyed on shrimps, fishes, crabs, and gammarid amphipods in nearly equal proportions. While the portion of the stomach contents attributable to shrimps and gammarid amphipods decreased with increasing fish size, consumption of fishes increased progressively. C. myiaster showed very constant prey selection regardless of prey availability-Especially fishes were heavily selected by this species throughout the year, although availability of fishes was lower than any other prey organisms in the eelgrass bed.

• Korean Journal of Ichthyology
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• v.9 no.1
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• pp.71-78
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• 1997

Stomach contents of snailfish, Liparis tanakai, caught in the Nakdong River Estuary were examined quantitatively. Liparis tanakai was a bottom feeding carnivores, and showed an almost strict specialization on shrimps and fishes. Shrimps and fishes accounted for 74.3% and 19.8% of the overall stomach contents, respectively. The most selected prey species was Cragon affinis for all fish size classes. The snailfish' s diets included minor quantities of crabs, amphipods, mysids and isopods. Small individuals(4~10 cm SL) consumed mainly shrimps which accounted for approximately 90% of the stomach contents. However, the portion of the diet attributable to shrimps decreased steadily with increasing fish size, and this decrease was paralleled by increased cosumption of fishes. For 31~45 cm individuals, fishes constituted over 30% of the stomach contents, while shrimps made up approximately 60% of the diet.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.16 no.2
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• pp.165-170
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• 2016

Nano-scale power splitter based on curved plasmonic waveguides are designed by utilizing the multimode interference (MMI) coupler. To analyze easily the adaptive properties of plasmonic curverd multimode interference coupler(PC-MMIC), the curved form transforms equivalently into a planar form by using conformal transformation method. Also, effective dielectric method and longitudinal modal transmission-line theory are used for simulating the light propagation and optimizing the structural parameters at 3-D guiding geometry. The designed $2{\times}2$ PC-MMIC does not work well for quasi-TM mode case due to the bending structure, and it does not exist 3dB coupling property, in which the power splitting ratio is 50%:50%, for quasi-TE mode case. Further, the coupling efficiency is better when the signal is incident at channel with large curvature radius than small curvature radius.

• Journal of the Korean Institute of Telematics and Electronics
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• v.12 no.4
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• pp.7-14
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• 1975

A significant new technique in the dsvelopment of micro-wave circuits is the process of untilization of coupled lines in the transverse electro-magnetic field. The bases for this technique are the application of even-and odd-mode characteristic impedances of the transmission line. This article describes the properties of directional couplers and explains a prccfdure usrd to design micro-strip directional couplers with the aid of the computer. The article also describes the experimental results obtained from seven microstrip couplers, which were built to verify the computer program and the approximate solutions. It can be seen that in cases at X-band where couplings of 10 to 20dB are required, the computer program and approximate solutions will produce good results.

• The KIPS Transactions:PartA
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• v.12A no.2 s.92
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• pp.103-108
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• 2005

The purpose of numerical analysis is to design an effective algorithm to realize some mathematical model on computer. In general the approximate value, which is obtained from computer operation, is not the same as the real value that is given by mathematical theory. Therefore the mr estimate measuring how approximate value is near to the real value, is the most significant task to evaluate the efficiency of algorithm. The limit of an error is used for mr estimation at the most case, but the exact mr evaluation could not be expected to get for there is no way to know the real value of the given problem. Wegmann's method has been researched, which is one of the solution to derive the numerical conformal mapping. We proposed an improved method for convergency by applying a low frequency filter to the Wegmann's method. In this paper we investigate error analysis based on some mathematical theory and propose an effective method which makes us able to estimate an error if the real value is not acquired. This kind of proposed method is also proved by numerical experiment.

• Bulletin of the Society of Naval Architects of Korea
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• v.6 no.1
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• pp.1-24
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• 1969

Added masses of two-dimensional cylinders of curvilinear-element sections with chines, which are similar to marked V character ship sections with either single or double chines, oscillating at high frequency in a free surface of an ideal fluid are calculated for both vertical and horizontal vibration by employing two particular two-parameter families of the conformal transformation. The numerical results are graphically presented in the forms of added mass coefficient curves in terms of the sectional area coefficient and the half beam-draft ratio together with the section contours derived with the employed transformations, and discussed in comparision with those of the Lewis forms and of straightline-element sections with single chine for vertical vibration, and, for horizontal vibration, with those of the Lewis forms.

• The Journal of the Korea institute of electronic communication sciences
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• v.17 no.2
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• pp.245-254
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• 2022

In this paper, a design optimization method for anti-jamming GPS antenna is presented. For this purpose, jamming performance analysis criteria and methods are presented. And based on the proposed analysis method, the antenna design elements that can realize the best performance were optimized. The anti-jamming GPS antenna for applying the presented method has a structure in which 7 radiating elements are arranged. Here, six radiating elements were circular arranged, and one element was arranged in the center of the circular arrangement. The optimized antenna design parameter(radius of the circular array) is 0.48 λ. As a result of the simulation, it was confirmed that when the steering angle(theta, phi) of the main lobe was (0°, 0°), the pattern null steering range(based on theta) was 57° to 90°.

• Journal of fish pathology
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• v.36 no.2
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• pp.403-408
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• 2023

Mullet is an important marine aquaculture fish species in Korea, with a total of 7,237 tons produced as of 2022, making it the 5th most produced marine aquaculture fish species. In this study, ectoparasites presumed to be isopods were discovered in the fins of farmed flathead grey mullet (average weight 550 g), and the characteristics of the parasites were confirmed. The length of the parasite was 5 to 18 mm, and 3 to 7 parasites were infected per fish. To analyze the characteristics of the parasites, molecular biological identification and phylogenetic analysis were performed using the cytochrome c oxidase subunit I (COI) gene, and it was confirmed to be most closely related to Nerocila japonica in the Cymothoidae family. To confirm the parasite control effect, a direct exposure drug sensitivity test was conducted on five types of aquatic drugs and fresh water, trichlorfon was confirmed to be effective.