• Korean Journal of Fisheries and Aquatic Sciences
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• v.18 no.3
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• pp.243-252
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• 1985

The mechanism of reproductive cycle of longchin goby Chasmichthys dolichognathus was investigated for the annual variations of gonadosomatic index(GSI), histological changes of gonad, reproductive cycle, and initiating and terminating factors of the breeding season. The experimental fish were captured in the tide pool of Tongbaeksom, Pusan, Korea from February 1983 to September 1984. Experimental fish for the study of initiating and terminating factors of the breeding season were maintained in filtered recirculating aquariums and exposed to various temperature and photoperiod regimes. The ovary is a pair of sac-shaped organ, and the testicular structure is tubular and it is connected to the seminal vesicle which is located at the posterior end of the testis. GSI began to increase from February when the water temperature began to increase and reached peak in April. It began to decrease from August, the top water temperature season, and maintained relatively low values until January. The annual reproductive cycle includes successive six developmental stages : early growing from December to February, late growing from January to March, early mature from February to May, late mature and ripe from March to August, spawning from April to July, degeneration and resting stage from May to December. An experimental study based on the reproductive cycle of this species indicated that rising temperature under long photoperiod during spring stimulated gonadal maturation, whereas terminating factor of the breeding season with recrudescence of the gonads was demonstrated as high water temperature during summer regardless of photoperiod.

• Korean Journal of Environment and Ecology
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• v.36 no.6
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• pp.615-626
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• 2022

This study investigated the habitat characteristics and spawning ecology of Hippocampus haema (Syngnathidae) in Soando Island, Korea, from May 2015 to December 2016. The survey site where seahorses inhabit was mainly formed by seagrass of Zostera marina populations. Total density and biomass (Mean±SE) of Z. marina were the highest at 136±14.4 shoots/m² and 489.8g DW/m², respectively, in spring (May), while the total density was lowest at 93±7.0shoots/m²in autumn (October), and biomass was the lowest and at 122.3g DW/m² in winter (February). During the study period, 293 individuals were identified through a diving and kick net survey, and the total length of H. haema ranged from 10.1 to 87.0mm. Male individuals nurturing fertilized eggs or larvae appeared beginning in May and were collected until October in both 2015 and 2016. Juvenile individuals were captured beginning in July 2015 and June 2016. As a result of a comprehensive analysis of the spawning season characteristics, it was estimated that the spawning season of H. haema was from April to October. The number of fertilized egg or larvae inside the male brood pouch were 38.3±14.8 (20-76), and the number of fecundity identified from female were 47.2±8.6 (31-59). The male-to-female ratio of H. haema was 1:1.7, indicating the dominance of males.

• 한국신재생에너지학회:학술대회논문집
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• 2005.11a
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• pp.595-598
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• 2005

The thermal performance of glass evacuated tube solar collectors are numerically and experimentally investigated. Four different shapes of solar collectors are considered and the performances of these solar collectors are compared. Dealing with a single collector tube, the effects of not only the shapes of the absorber tube but also the incidence angle of solar irradiation (beam radiation) on thermal performance of the collector are studied. However the solar irradiation consists of the beam radiation as well as the diffuse radiation. Also, the interference of solar irradiation and heat transfer interaction between the tubes exist in an actual solar collector. These effects are considered in this study experimentally and numerically the accuracy of the numerical model is verified by the experimental results. The result shows that the thermal performance of the absorber used a plate fin and U-tube is the best.

• Journal of radiological science and technology
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• v.6 no.1
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• pp.81-84
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• 1983

Scattered-rays are produced from objects in x-ray diagnosis and the quality of x-ray image is influenced by presence of the scattered-ray. Therefore, constant ways and means to suppress and to eliminate the scattered-ray were devised. Authors made an experimental study on the scattered-ray content in transmitted-ray using acryl phantoms and obtained the results as follows: 1. The scattered-ray content in transmitted-ray is not influenced by filtration and tube voltage. 2. Irradiated field size and the thickness of object are a potent influence to scattered-ray content.

• Korean Journal of Ichthyology
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• v.23 no.3
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• pp.246-249
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• 2011

Twenty five specimens (40.8~58.4 mm SL) of Gymnogobius taranetzi (Family Gobiidae) were collected from the estuary of Samcheok-si and Yangyang-gun, Gangwon-do, Korea. This species is distinguished from other Gymnogobius species by oculoscapular canals not extending anteriorly through interorbital space, but replaced by rows of sensory papillae; oculoscapular canal pore C is absent; some yellow bands on body in female with breeding color. The new Korean name "Dong-hae-nal-mang-duk" is proposed for this species.

• The Korean Journal of Malacology
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• v.2 no.1
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• pp.26-29
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• 1986

Corbicula fluminea, one of the 2 species in the family Corbiculidae living in the Lake Uiam, was used as an experimental material and the embryonic development and the structure of glochidia of this species were investigated. This freshwater mussels was oviparous, but some ovoviviparous: incubated their youngs in the inner-demibranchs or outer-demibranchs, however, chiefly used the inner-demibranchs as brood-pouch. The average time required from a fertilized egg to two-cell stage, veliger stage, and glochidium was 76 minutes, 3 hours, and 17 hours, respectively, The mean size of glochidium was $168{\mu}m$ in shell height, $195{\mu}m$ in shell lengh, $114{\mu}m$ in hinge legth and the form of glochidium was D-type and had no hooks or hooklets for attaching to fish like Unioidae.

• KOREAN POULTRY JOURNAL
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• v.41 no.9
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• pp.102-105
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• 2009

농촌진흥청 국립축산과학원(원장 라승용)은 지난 15년간의 재래닭 수집과 순계 복원, 연구 및 개량을 통해 '우리맛닭'을 탄생시켰다. 재래닭 복원 프로젝트는 1994년부터 1997년까지 4년간 대한양계협회에서 '재래닭육용화 사업'의 일환으로 서울대학교 오봉국 박사(본회 고문)의 진두지휘 하에 대학교 수 16명, 연구관 8명 등 연인원 84명과 9억2천만원의 예산이 투입되어 진행됐으며, 11개의 과제를 수행해 마침내 재래닭 순계 복원에 성공하였다. 연구진은 이후 연구 결과물을 축산과학원으로 이관하여 후속연구를 지속토록 하였으며, 축산과학원은 이로부터 우수한 실용계를 생산하는 연구에 착수하게 됐다. 이러한 과정을 거쳐, 경제적으로 불리한 기존 재래닭의 문제점을 보완하여 산란성과 산육성이 우수한 닭으로 개발한 것이 바로 '우리맛닭'이다. '우리맛닭'은 축산과학원이 보유한 9개 순계 모군으로부터 성장이 빠른 부계통과 맛이 좋고 알 생산이 많은 모계통의 교잡을 통해 맛이 좋고 성장이 빠른 실용계로 생산된다. '우리맛닭'은 콜라겐 함량이 높아 탄력감과 쫄깃한 느낌의 육질을 지니고 있으며, 이를 접하는 소비자들의 반응도 좋게 나타나 그 가능성이 긍정적으로 점쳐지고 있다.

• Korean Journal of Optics and Photonics
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• v.1 no.1
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• pp.58-64
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• 1990

The flow direction in a glass tube is measured by using a forward scattering dual beam laser Doppler velo$.$ cimeter with an acousto-optic modulator. We can determine the flow direction by measuring the shifted Doppler frequency which is dependent on the order of modulation of the laser beam and the fluid flow direction. Also. an electronic amplification circuit which has a bandwidth of 0 . 300 MHz and a gain of 38 dB is designed and fabricated to amplify the high frequency signal.signal.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.24 no.3
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• pp.331-336
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• 2013

In this paper, plasma modeling is achieved using fluid dynamics, thereby electron density is derived. The way proposes the key to overcoming the limitations of conventional researches which adopt simplified plasma model. The result is coupled with Maxwell-Boltzmann system in order to calculate scattering waves in various incident angle. The first part is dedicated to perform plasma modeling in dielectric barrier discharge(DBD) structure. Suzen-Huang model is adopted among various models due to the fact that it uses time independent variables to calculated potential and electron distribution in static system. The second part deals with finite difference time domain(FDTD) scheme which computes the scattered waves when the modulated Gaussian pulse is incident. Founded on it, radar cross section(RCS) is observed. Consequently, RCS is decreased by 1~2 dB with DBD plasma. The result is analogous to the RCS measurement in other researches.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2000.05a
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• pp.451-454
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• 2000

The impact ionization(I.I.) is necessary to analyze carrier transport properties under the influence of high electric field. The full band I-k relation and Fermi's golden rule are used for the calculation of impact ionization rate. We have investigated the temperature- and field-dependent impact ionization coefficient for silicon using full band Monte Carlo simulation. The impact ionization coefficients calculated by our impact ionization model are agreed with experimental data at look. We know that impact ionization coefficients and electron energies are decreasing along increasing temperature due to increase of phonon scattering, especially by emission. The logarithm of impact ionization coefficients are fitted to linear function for temperature and field. The residuals of linear function are within the error bound of 5%. We know logarithmic impact ionization coefficients are linearly dependent on temperature and field.