• Korean Journal of Fisheries and Aquatic Sciences
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• v.48 no.2
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• pp.221-232
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• 2015

Broadband echoes measured in live chub mackerel Scomber japonicus, goldeye rockfish Sebastes thompsoni, and fat greenling Hexagrammos otakii with different morphologies and internal characteristics were analyzed in time and frequency domains to understand the species-specific echo feature characteristics for classifying fish species. The mean echo image for each time-frequency representation dataset obtained as a function of orientation angle was extracted to mitigate the effect of fish orientation on acoustic scattering. The joint time-frequency content of the broadband echo signals was obtained using the smoothed pseudo-Wigner-Ville distribution (SPWVD). The SPWVDs were analyzed for each echo signature of the three fish species. The results show that the time-frequency analysis provided species-specific echo structure patterns and metrics of the broadband acoustic signals to facilitate fish species classification.

• Transactions of the Korean Society of Automotive Engineers
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• v.9 no.2
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• pp.19-27
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• 2001

This paper is the first of 3 companion papers which investigate axial stratification process. In-cylinder fuel behavior has been investigated in the port injected SI engine by visualization for the purpose of understanding stratification. Planar laser light sheet from an Nd:YAG laser has been illuminated through the transparent quartz cylinder of the single cylinder optical engine and the Mie scattered light has been replaced with an air-ethanol mixture to utilize atomized fuel spray for the visualization purposes. This results have been compared with steady flow concentration measurement. For no swirl port, the axial penetration depends on the fuel injection timing. The fuel tends to remain in the upper region of the cylinder far from the spark plug and the distribution is not affected by the injection timing except 90 ATDC.

• Proceedings of the Korea Air Pollution Research Association Conference
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• 2002.11a
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• pp.187-188
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• 2002

다양한 오염원에서 배출된 오염물질은 가시광선 산란에 의한 시정악화 (visibility impairment), 산성 침착 (acidic deposition) 등과 같은 지역규모 (regional scale)의 대기오염문제와 오존층 파괴, 온실효과 등과 같은 지구규모 (global scale)의 대기오염문제를 야기 시켰으며, 더 나아가 인간의 건강과 복지에도 심각한 악영향을 미치고 있다. 이와 같은 문제는 환경에 대한 관심을 고조시켰으며 이러한 대기오염문제를 해결하기 위한 기술적, 경제적, 행정적 투자와 많은 연구들을 증대시키는 결과를 초래하였을 뿐만 아니라 대기오염 피해로 인한 건강 및 복지손실을 최소화하고 산업체의 경제적 손실을 최소화하기 위해 합리적인 각종 대기환경 관리기술이 도입되고 개발될 필요성 또한 대두되었다. (중략)

• Journal of the Korea Institute of Information and Communication Engineering
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• v.8 no.3
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• pp.563-569
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• 2004

The formulas taking into account the fundamental features of a meteoric radio propagation are obtained. Numerical simulation analysis has shown complex space structure of a field. Time behavior of intensity are researched taking into account nonstationary model. It is shown, this behavior essentially depends on parameters of a meteor trail, and that there is large variety of time dependencies of the signal intensity at the single scattering. In particular, at appropriate parameters of a meteor underdense trail it is possible large duration meteor bursts with which usually refer to an overdense meteor propagation.

• Korean Journal of Poultry Science
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• v.36 no.1
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• pp.85-88
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• 2009

One of the mitochondrial genes, called cytochrome c oxidase I (COI), has been widely used for the species identification (called bio-barcode) in birds. In this study, the bio-barcode has been applied to chicken breeds in Korea whether it also can be used as a molecular marker for breed identification. Data indicated that Korean native chicken has the mixed SNP (single nucleotide polymorphism) patterns between White Leghorn (Layer) and Cornish (Broiler) and ultimately, it can not be used as the marker for breed identification. However, this result indicates the mixed use of the Korean native chicken, since it has been used for dual purpose for producing meat and egg for a long time. In order to use as a marker for species identification, more reliable mitochondrial and/or nuclear DNA markers need to be developed.

• Journal of the Korean earth science society
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• v.23 no.8
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• pp.707-721
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• 2002

Seafloor acoustic image data using the side scan sonar system were gathered on the Sindu-ri offshore near the Taean peninsula, middle western Korea. The relationship between the back-scattering acoustic intensity and the sea-bottom sediment properties was studied. And these two data sets were compared and interpreted with the water depth, respectively. Most of sediment properties were correlated well to the acoustic intensity, however the distribution patterns of the sea-bottom sediment and the seafloor acoustic image were not similar to each other except the rocky bottom area. The water depth was not only influential on the distribution pattern of seafloor acoustic image but also showed a linear relation with the sediment properties distribution.

• Progress in Medical Physics
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• v.9 no.4
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• pp.247-257
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• 1998

For effective radiotherapy, it should always be considered that calculation of different dose distribution in heterogenous tissue is important particularly on lung which has low density and large volume. To take precise dose distribution of 6MV X-ray in the thoracic cage, the authors had made a tissue equivalent phantom for thorax, measured dose distribution by thermoluminescent dosimeter and mm dosimeter, and derived methmetical equation coincided with provided theoretical formula. In comparision with isodose curve on case of homogeneous soft tissue, dose of heterogeneous lung tissue had been shown increase about 4% per cm depth on one and multiportal field, less than 15% difference on rotation field for esophagus, and around 20% difference on rotation field for lung according to the degree of rotation angle that must be corrected by dose compensation.

• Korean journal of applied entomology
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• v.14 no.3 s.24
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• pp.163-166
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• 1975

This experiment was performed to investigate the X-ray sensitivities at the various stages of life cycle and to determine the sterillizing dose of stable fly, Stomoxys calcitrans(L). A dose of 300 rad caused about $50\%$ mortality in 2-hour-old eggs as measured by egg hatch, and $100\%$ mortality was obtained with a does of 1 Krad. Sub-lethal dose $(LD_{50})$ for the pupal mortality after irradiation of 3-5days old pupae were 11.5 Krad and the mortality was decreased with increasing pupal age at irradition. A significant reduction of egg hatch by $1.5\%$ was observed when treated males with 3 Krad at pupal stage were mated to untreated virgin femleas. On the other hand, $100\%$ sterility in females was resulted by 2 Krad irradiation and oviposition was completely inhibited with 3 Krad. Thus, both sexes of stable fly could be sterilized with a dose of 4 Krad irradiated to 3-5 days old pupae.

• Korean Journal of Optics and Photonics
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• v.30 no.1
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• pp.1-7
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• 2019

MANPADS (man-portable air defense system) is a counterweapon system against enemy aircraft, tracking the MWIR (mid-wavelength of infrared) signature of the plume. Under foggy conditions, however, multiple scattering phenomenon caused by the particles affects the MWIR transmittance, and the MANPADS detection performance. Therefore, in this study we analyzed the lock-on range of MANPADS with varying fog conditions and plume characteristics. To analyze the optical extinction properties and transmittance in fog, Mie scattering theory and analytic solution of the radiative-transfer equation are utilized. In addition, we used flare signature as an alternative MWIR light source. We confirmed that the lock-on range could be noticeably reduced under conditions of mist, and proportional to the flare temperature.

• Korean Journal of Ichthyology
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• v.4 no.2
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• pp.1-25
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• 1992

Taxonomic study of the five species (Acanthogobius elongata, A. flavimanus, A. lactipes, A. luridus and Synechogobius) from Korea was carried out based on morphometric, cephalic sensory canal and ecological characters. Taxonomic revision and classificational keys are provided. Synechogobius hasta is easily distinguished from four species of the genus Acanthogobius in eleven characters, i. e., the number of dorsal and anal fin rays, the transverse scales, the vertebral numbers, the formula of interneural spine of the first dorsal fin, the number of interhemal spine anterior to the first hemal spine, the number of epipleural and pleurals, the ratio of caudal peduncle length, the ratio of caudal peduncle depth and the regular variations in the ratio of body parts with the body length. In the genus Acanthobobius, A. elongata is distinguished from other 3 congeneric species in the ratio of body parts and the oculoscapular sensory canal. Moreover, A. flavimanus differs from other 3 congeneric species in the lateral scales, the transverse scales, the number of predorsal scales, the vertebral number, the number of epipleural and pleurals. Sensory papillae rows of S. hasta is not similar that of the genus Acanthogobius in having a singular sensroy papillae rows. A. elongata has no oculoscapular sensory canal D and A. flavimanus has transverse sensory papillae in cheek, and these are one of the unique characters distinguished form other congeneric species. In the spawning period inferred from gonadosomatic index, A. elongata varied from late March to late June ; A. flavimanus, January to April ; A. lactipes, May to September ; A. luridus, early May to early July and S. hasta, early March to early May.