• Parasites, Hosts and Diseases
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• v.30 no.4
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• pp.245-254
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• 1992

Total 242 Rana nigromaculata and g R. catesbeiana were collected from the various localities in Korea from February 1989 to July 1991, and their lungs were examined. Five species in genus Haematoloechus, i. e., H. sibiricus japonicus (Yamaguti, 1936), H. nanchangensis Hsiung, 1934, H. variegatus (Rudolphi, 1819), H. lobatus (Seno, 1907), H. lobatus koreanus, were identified in this study. Among them, H. lebatus koreanus was a new subspecies and H. variegatus and H. lebatus were newly recorded from Korea.

• Korean Journal of Weed Science
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• v.32 no.1
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• pp.10-16
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• 2012

This study was carried out to investigate the agronomic traits, comparison of weed characteristics and possibility of gene flow in 'vitamin A enforced GM rice' and the donor plant, 'Nagdong'. The GM rice was not significantly different agronomic traits compared to the donor plant, Nagdong. Weed population changes were investigated in the cultivation of the GM rice and the donor plant, Nagdong. Dominant weed species and their dry matter did not show the difference between GM rice and the donor plant, Nagdong in macro-GM crop field. Dominant weed species with the GM rice and the donor plant, Nagdong were Monochoria vaginalis, followed by Eleocharis kuroguwai, Echinochloa crus-galli and Lindernia procumbens. The detection of gene from the GM rice was done using PCR, gene flow can't be detected by weed species. Results of this study on the agronomic traits, weed characteristics and possibility of gene flow has elucidated that GM rice might not be different from the donor plant, Nagdong.

• The Korean Journal of Mycology
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• v.12 no.2
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• pp.75-77
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• 1984

An undescribed Cercospora leaf spot of pepper grown in a greenhouse was observed at Jinju area in 1983. The symptom of this disease showed frog eyes spot on lower leaves of pepper. Leaves and petiole of pepper plant inoculated with spore suspension of this pathogen app­eared leaf spot after 2 weeks and exhibited cicular, brown frog eyes spot. This fungus was grown slowly on PDA and produce condia on infected leaves. The occurrence of this disease was responsi­ble for factors with high temperature and humidity conditions in the ill-ventilated greenhouse. This causal fungus was identified as Cercospora capsici Heald et. Wolf from the shape and length of the conidiophores, the length of the condia, and pathogenic behaviors.

• The Korean Journal of Zoology
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• v.39 no.3
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• pp.266-272
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• 1996

Experiments were carried out to ascertain whether gonadotropin or a phorbol ester (12-O-tetradecanoyl phorbol-13-acetate, TPA) induces oocyte ovulation and stimulates prostaglandin synthesis by Rana ovarian follicles in vitro. Rana nigromaculata collected from underground in spring were utilized for the present experiment. Treatment of frog pituitary homogenate (FPH) or TPA to ovarian fragments in culture induced oocyte ovulation in a dose dependent manner and stimulated prostaglandin F2a (PGF$_2$$\alpha$ synthesis. Both treatruents were more effective in inducing the ovulation and PGF$_2$$\alpha$ secretion by the follicles obtained in May than those in April. A Protein kinase C inactivator, 1-(5-isoquinolinyl-sulfonyl)-2-methyl-piperazine (H-7), or cyclooxygenase inhibitor, indomethacin (IM) suppressed the FPH- or TPA-induced PGF$_2$$\alpha$ production, but IM failed to suppress the FPH- or TPA-induced ovulation. Time course of oocyte ovulation and PGF$_2$$\alpha$ secretion by FPH and TPA treatments were very similar to each other. FPH stimulated progesterone secretion by the follicle but TPA failed to do so. Taken together, the data presented here suggest that protein kinase C (PKC) in follicle play a role in the ovulation process of Rana nigromaculata, probably via prostaglandin synthesis.

• Parasites, Hosts and Diseases
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• v.23 no.1
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• pp.72-78
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• 1985

A total of 220 tadpoles was captured in 6 areas and total 117 frogs, Rana nigromacuzata, were collected in 11 areas in Korea. They were examined for their infection status by the metacercariae of Fibricola seoulensis by peptic digestion technique and by histological observation with hematoBylineosin staining. This study was carried out from August, 1983 to September, 1984. Followings are the results. 1. The tadpoles of R. nigromaculata were positive for the metacercariae from 3.3% to 100% by area. The number of metacercariae per infected tadpole ranged from 1 to 584, and the mean number Per tadpole ranged from 7.6 to 221 by area. 2. The metacercariae from 16 tadpoles were counted by the body portion. A great majority of the metacercariae was collected from abdominal cavity, 98.3% of 484 counted larvae. And 6(1.2%) larvae were from proximal tail and 2(0.4%) from trunk. 3. Histological sections of tadpoles showed many metacercariae in abdominal cavity but none in other parts. The larvae were free in the spaces among intestinal loops or around primitive liver. A few larvae were in duct-like tissues near trunk wall. There was little infiltration of inaammatory cells. 4. The metacercarial infection rates of frogs ranged from 0% to 100% by area. The larval burden was 1 to 470 by infected frogs, and mean number ranged from 1 to 175.6 by area. By above results, it is suggested that the cercariae of F. seoulensis may infect R. nigromaculata already in the stage of tadpole. Almost all of the metacercariae were concentrated in abdominal cavity of tadpoles. According to the infection status of frogs, this nuke is prevalent almost nationwidely in rice paddies in Korea.

• Korean Journal of Environmental Biology
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• v.21 no.1
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• pp.45-51
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• 2003

Genetic diversity of local populations among geologically isolated groups of Rana amurensis was refined by sequence comparison of the mitochondrial (mt) 165 rDNA genes. Each 401 base pairs of DNA sequences, which was determined from four local populations of Rana amurensis, two local populations of R. nigromacutata, and three species of the genus Rana were used in this analysis. Despite morphological similarity of Rana amurensis, Korean populations were well distinguished from the other groups on the basis of 105 rDNA gene difference. Further analyses for additional local populations belonging to R. amurensis will be necessary to clarify the taxonomic status.

• The Korean Journal of Zoology
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• v.32 no.3
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• pp.258-263
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• 1989

Nuclear Transplantation between Rana pipiens and Rana dybowskii When diploid blastula nuclei of Rana pipiens are traraplanted into enucleated eggs of Rana dybowskii the resulting nucleocytoplasmic hybrids are lethal-those development were arrested around the stage of the dorsal lip formation For the improvement of developmental capacity, serial nuclear transplantation was carried out. Even though serial transplantation of 15 generations showed normal development in each generation until gastrula stage, there was no sign of fundamental improvement in development afterward. This results implied that up to gastrulation normal DNA replication and cell division can take place in foreign cytoplasm. Since chromosomal aberrations both in shape and number were usually observed, the nuclei must have been modifted while resided in the foreign cytoplasm. Those nuclei didn't participate in normal development and led the embryos to early death. Tissue graft experiment indicated that the abnormal behavior of this lethal nucleocytoplasmic hybrid is an inherent property which is not corrected by the contact with its own tissue.

• Journal of The Korean Association For Science Education
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• v.15 no.4
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• pp.487-494
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• 1995

본 연구는 우리 나라의 성인들이 자신의 초중등 학교 시절 경험하였던 학교 과학교육에 대해 어떤 종류의 즐거운 혹은 괴로운 기억들을 현재까지 갖고 있는가를 탐색하였다. 성인들은 오래 전 경험하였던 매우 인상적인 활동이나 장면들을 통해 학교 과학교육을 기억할 것이고, 이러한 기억은 그들의 학교 과학교육에 대한 전반적인 태도에 결정적인 역할을 할 것이다. 따라서 성인들의 학교 과학교육에 대한 이러한 기억들을 살펴보면, 학교 과학교육의 특징을 이해하고 장기적으로 학교 과학교육을 보다 즐거운 경험의 장으로 만드는 데 도움이 될 것이다. 본 연구는 소규모의 설문 조사를 통해 이루어졌으며, 설문 대상은 대구지역의 30-50대 성인 88명이었다. 설문은 현재 과학과 관련된 특정한 직업을 갖고 있지 않은 사람을 대상으로 하였으며, 설문에서 응답자들은 자신들의 초중등 학교 과학교육을 받으면서 가장 즐거웠던 기억과 가장 괴로웠던 기억이 구체적으로 무엇이며 이러한 경험은 초중고 어느 때이었는가를 응답하였다. 성인들이 가장 즐거웠던 기억으로 지적한 것은 실험 실습 활동(65.9%), 야외학습 활동(19.3%) 등으로 전통적인 교실수업 이외의 활동이 약 86%로 나타났다. 그리고 효과적인 교실수업, 교사의 인성적 특징, 과학전람회 참가 등의 경험을 언급한 경우도 부분적으로 있었다. 성인들이 가장 괴로웠던 기억으로 지적한 것은 따분한 교실수업(51.1%), 실험 실습 활동의 부정적인 측면(28.4%) 등으로 나타났으며, 부분적으로 과다한 숙제, 교사의 인성적 특징, 야외학습 활동, 과학수업의 부재 등을 지적한 경우도 있었다. 또한 전체적으로 즐거웠던 기억은 국민학교 시절의 경험에서(56.8%), 반면 괴로웠던 기억은 고등학교 시절의 경험에서(44.3%) 많이 나타났다. 특히, "개구리 해부 실험" 의 경우, 7명이 가장 즐거웠던 기억으로 8명은 가장 괴로웠던 기억으로 언급하여 매우 상반된 견해를 나타냈다. 따라서 동일한 활동일지라도 학생들에게는 매우 상반된 경험으로 작용하게 되며, 이 경우 생명체에 대한 과학실험의 윤리적 문제와 이에 대한 갈등을 분명하게 드러냈다.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.37 no.4
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• pp.28-34
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• 2000

In this paper, a continuous-time filter for low voltage and high frequency applications using fully-balanced current integrators is presented. As the balanced structure of integrator circuits, the designed filter has improved noise characteristics and wide dynamic range since even-order harmonics are cancelled and the input signal range is doubled. Using complementary current mirrors, bias circuits are simplified and the cutoff frequency of filters can be controlled easily by a single DC bias current. As a design example, the 3rd-order lowpass Butterworth filter with a leapfrog realization is designed. The designed fully-balanced current-mode filter is simulated and examined by SPICE using 0.65${\mu}{\textrm}{m}$ CMOS n-well process parameters. The simulation results show 50MHz cutoff frequency, 69㏈ dynamic range with 1% total harmonic distortion(THD), and 4㎽ power dissipation with a 3V supply voltage.

• Applied Microscopy
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• v.37 no.4
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• pp.209-217
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• 2007

The system of wound healing is very complex biological processing that includes inflammatory, reepithelialization, and matrix construction. For identification of the transitional pathway of the keratinocytes, we have employed immunohistochemical analysis using cytokeratin antibody after wounding. Epithelium in skin of the frog(Bombina orientalis) was examined with transmission electron microscopy. Cytokeratin was expressed in normal basal and gland cavity cells. At 3-hour basal layer cells were strong positive, however cells of the upper layer were negative reaction. Day1 and 2 after post-wounding, regenerating epithelial cell layer was positive reaction, especially basal layer cells were strong positive. At day 10 after wounding, the degree of positive reaction to basal cells of regenerating epithelial tissue was equal to day 7 wound tissue. At day of 19th, basal and spinous layer cells were strong positive reaction. Regenerating epithelial cells were positive but some basal cells were strong positive at day 27. From this result, we identified that the migration of the keratinocytes in amphibian skin wounds is initiated from basal layer fells and the keratinocytes migrate into basal and middle of the wound area.