• Communications of Mathematical Education
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• v.9
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• pp.73-81
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• 1999

7차 교육과정을 시행에 앞서, 현재 초등학생들이 수학을 어떻게 생각하고 있으며, 어 떤 이유로 수학에서 학습 부진을 느낄까? 라는 문제의식을 갖게 되었다. 그래서 정규교육의 첫 단계인 초등학교 수학교과에 대한 인식 및 학습 부진에 관한 연구를 시행하고자 했다. 본 연구대상은 대전 ${\cdot}$ 충남 지역에 소재하고 있는 6개 초등학교 6개 반을 선정하여 발달사고과정에서 자신의 생각을 분명하게 나타낼 수 있는 4학년에서 6학년을 연구대상으로 선정하여 교과요인에 대한 설문조사를 하였다. 본 연구는 수학교과에 대해초등학생들이 어떤 생각을 가지고 있고, 어떤 교과요인을 학습하는데 어려움을 느끼는지를 알아봄으로써, 본 연구 결과를 기초로 중학생 ${\cdot}$ 고등학생 ${\cdot}$ 대학생들까지 연속하여 수학교과에 대한 인식을 조사하고 함이며, 새롭게 시행될 7차 교육과정에서의 수학교과 구성면과 수학 학습 및 교수 방법론에 보다 바람직하고 효과적인 시사점을 제공하고자 한다.

• The Korean Journal of Malacology
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• v.31 no.1
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• pp.9-19
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• 2015

Germ cell development and cyclic changes in the epithelial cells of the seminal vesicle of the male rapa whelk, Rapana venosa, were investigated by cytological and histological observations. The process of germ cell development can be classified into five stages: (1) spermatogonial, (2) primary spermatocyte, (3) secodary spermatocyte, (4) spermatid, and (5) spermatozoon. In particular, four atypical cells (Type IA, IB, IIA and IIB cells) occur among normal germ cells in the acini during spermatogenesis. Presumably, the atypical cells, which have lysosome-like vacuoles or lysosome-like bodies in the cells, are involved in breakdown and absorption themselves in the acini. However, atypical cells were not found in the epithelial cells of the inner layer of the seminal vesicle. A considerable amount of spermatozoa are transported from the testis towards the the seminal vesicles until late July. The main coupulation period is between June and July. The process of the cyclical changes of the seminal vesicles can be classified into three phases: (1) resting, (2) accumulating, and (3) spent. Yellow granular bodies are involved in resorption or digestion of residual spermatozoa.

• Proceedings of the Korean Society of Fisheries Technology Conference
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• 2000.05a
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• pp.518-519
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• 2000

재첩류는 담수와 기수역에 넓게 분포하는 식용 패류로서, 일본재첩은 우리 나라 기수역에서 다량 서식하는 유용패류이다. 일본재첩에 관한 연구는 생식생태학적연구 (조비,1941: 조등, 1997; 조 등,1998)와 생장(宇藤, 1981)이 있을 뿐이다. 그러나, 국내에 서식하는 일본재첩, Corbicula japonica의 생식생태에 관한 연구가 매우 미진할 뿐만 아니라, 이들의 생식생태에 관한 계수학적 정량분석조사는 되어있지 않다. 따라서, 본 연구는 일본재첩의 생식생물학적연구의 일환으로 생식소의 구조, 생식주기, 생식소지수의 월별변화, 생식세포발달과정, 성비를 조사하였고 계수학적 정량분석을 실시하였다. (중략)

• Survey Research
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• v.1 no.2
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• pp.137-159
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• 2000

In this paper, the following facts have been reviewed: First, statistics should have the characteristics of descriptive, inferential, and applicative statistics in "information-Knowledge Society." Second, the computer has been employed in the process of data collection and data analysis for producing the statistics with timeliness and efficiency. Third. we have to develop a statistical development plan which lays emphasis on the production of applicative statistics in the coming "Internet Cyber Society" In addition, we investigated overall status of computer utilization, and the process of the development of computer-assisted statistical survey methods. The prospects of internet surveys were also investigated here. On the basis of the above review and investigation, we suggested "an integrated system of computer-assisted statistical surveys" that can be applied to all kinds of surveys and statistics.

• Journal of Embryo Transfer
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• v.6 no.1
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• pp.1-11
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• 1991

가축의 일란성 쌍태를 생산하기 위한 기술 개발을 확립하고자 상실배 및 포배기에 있는 BALB/c 계통의 생쥐 수정란을 micromanipulator로 분할 수정란을 작출하고 이를 체외배양을 실시하여 발달성적을 조사하였으며, 외과적 및 비외과적 이식을 실시하여 착상율 및 산자생산 성적을 조사한 결과는 다음과 같다. 1. 상실배 및 포기배에 있는 총 811개의 정상적인 수정란을 분할하여 이중에서 666(82.1%)개가 분할시의 물리적인 손상이 없이 분할되었고, 이때 분할 성공율은 발달단계 간에 유의적(P<0.05)인 차이가 없었다. 2. 분할 수정란중 상실배는 30-36시간, 초기 배반포 및 확장 배반포는 3-6시간 배양을 실시한 결과 분할 수정란중 한쌍이 모두 정상적으로 배양된 것은 각각 70.0%, 80.4% 및 73.1%로써 이들 발달단계 간에 유의적(P<0.05)인 차이가 없었다. 3. 분할된 상실배와 정상적인 수정란의 이식후 수태율은 각각 63.6% 및 61.3%로써 유의적(P<0.05)인 차이가 없었다. 그러나 분할된 상실배에 있어서 배양을 하지 않고 이식한 경우에는 전혀 수태되지 않았다(P<0.05). 4. 분할된 포배기 수정란을 체외 배양후 이식한 수태율(55.5%)과 배양과정을 거치지 않고 이식한 성적(43.8%) 그리고 정상적인 포배기 수정란을 이식한 수태율(55.4%) 간에는 유의적(P<0.05)인 차이가 없었다. 5. 분할 수정란을 외과적 방법으로 이식한 경우는 52.8%의 수태율을 얻었으나, 비외과적 방법으로 이식한 경우 27.5%로써 외과적 방법으로 이식한 경우보다 수태율이 유의적(P<0.05)으로 낮았다.

• Proceedings of the Korean Association for Survey Research Conference
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• 2000.06a
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• pp.137-159
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• 2000

In this paper, the following facts have been reviewed: First, statistics should have the characteristics of descriptive, inferential, and applicative statistics in "information-Knowledge Society." Second, the computer has been employed in the process data collection and data analysis for producing the statistics with timeliness and efficiency. Third, we have to develop a statistical development plan which lays emphasis on the production of applicative statistics in the coming "Internet Cyber Society." In addition, we investigaated statistical survey methods. The prospects of internet surveys were also investigated here. On the basis of the above review and investigation. we suggested "an integrated system of computer-assisted statistical surveys" that can be applied to all kinds of surveys and statistics.nds of surveys and statistics.

• Applied Microscopy
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• v.34 no.2
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• pp.103-111
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• 2004

Fresh specimens of the aquatic macrophyte, Spirodela polyrhiza, have been examined employing scanning and transmission electron microscopy. Observations revealed the occurrence of microbial colonization during development. Submerged parts of the small, free-floating S. polyrhiza body exhibited a variety of microorganisms such as bacteria, cyanobacteria, and diatoms throughout their development. However, immature and/or young plants normally demonstrated much less microbial colonization compared to mature plants. During the study, heavy colonization by the microorganisms was routinely encountered at maturity, especially in the fully developed abaxial fronds and root caps. The mucilaginous layer was shown along the root caps, and the microorganisms appeared to be either clustered or attached to this layer. In contrast, only moderate degrees of colonization were observed in the root, and little to no colonization was observable in the adaxial frond surface. Transmission electron microscopy clearly demonstrated the microbial colonization to be external in the S. polyrhiza specimen examined in the current study. The association between the microorganisms and S. polyrhiza has been considered non-harmful, as no frond senescence and almost no mechanical penetration of the plant by the microorganisms were noticed during the study.

• Korean Journal of Ecology and Environment
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• v.33 no.4 s.92
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• pp.395-404
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• 2000

The gonadosomatic index (GSI), hepatosomatic Index (HSI), egg size distribution, gonad development and reproductive characteristics of venus fish, Aphyocypris chinensis, were examined during March 1997- March 1998 in agricultural waterways of the Sedo-myun, Puyo county, Chungnam Province, Korea. Annual reproductive cycle was classified into the following five successive phases by monthly changes in GSI and the characteristics of ovary: quiescent phase (January- February), secondary growing and mature phase (March-May), ripe and spawning phase (June-July), degenerating and resting phase (August-September) and primary growing phase (October-December). The hepatosomatic index (HSI) showed clear seasonal pattern with two separate peaks. However, it exhibited a negative correlation to changes of GSI values. The regression analysis suggested that fecundity showed a strong positive linear relationship ($r^2\;=\;0.91$, n = 34) with body weight. The sex ratio of female to male was 1.4 : 1 in the natural population during the study. The minimum reproductive size of female and male venus fish was 38 mm and 33 mm in fork length, respectively.

• Korean Journal of Childcare and Education
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• v.10 no.4
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• pp.159-176
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• 2014

This study aims to examine the suggestions by studies that family predictors are related to developmental outcomes more strongly for children reared principally by their parents compared to those with extensive child care experience. Zero-order correlations between family predictors and developmental outcomes were conducted and the significance of differences in correlation coefficients between the two child care groups were examined. There was no evidence that there exist systematic differences between the two groups in predictive power of family factors except a few exceptions. At 2 years, social parenting style was more strongly associated with communication ability in the extensive child care group. At 3 years, some HOME subscales were related to a child's expressive and receptive vocabulary skills in significantly greater magnitudes in the mother care group. The findings also implied the potential contribution of child care environment on developmental outcomes for those who spend extensive hours in nonmaternal care.

• Journal of The Korean Association For Science Education
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• v.36 no.1
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• pp.177-190
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• 2016

The purpose of this study is to validate learning progressions for Earth's motion and solar system from two different perspectives of validity. One is construct validity, that is whether a hypothetical pathway derived from our study of LPs is supported by empirical evidence of children's substantive development. The other is consequential validity, which refers to the impact of LP-based adaptive instruction on children's improved learning outcomes. For this purpose, 373 fifth-grade students and 17 teachers from six elementary schools in Seoul, Kangwon province, and Gwangju participated. We designed LP-based adaptive instruction modules delving into the unit of 'Solar system and stars.' We also employed 13 ordered multiple-choice items and analyzed the transitions of children's achievement levels based on the results of pre-test and post-test. For testing construct validity, 64 % of children in the experimental group showed improvement according to the hypothetical pathways. Rasch analysis also supports this results. For testing consequential validity, the analysis of covariance between experimental and control groups revealed that the improvement of experimental group is significantly higher than the control group (F=30.819, p=0.000), and positive transitions of children's achievement level in the experimental group are more dominant than in the control group. In addition, the findings of applying Rasch model reveal that the improvement of students' ability in the experimental group is significantly higher than that of the control group (F=11.632, p=0.001).