• The Korean Journal of Malacology
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• v.13 no.1
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• pp.55-64
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• 1997

꼬막, Tegillarca granosa은 우리나라 남해 및 서해안 일대에서 서식하는 중요한 수산자원 중의 하나이지만, 이에 대한 생물학적 기초연구는 거의 없는 실정이다. 따라서 1995년 2월부터 1996년 1월까지 전남 벌교연안에서 채집한 꼬막의 생식소발달, 생식세포형성과정 및 생식주기를 조사하였다. 1. 꼬막은 자웅이체이면서 난생이고, 생식소는 내장낭의 간중장선을 싸고 있는 결합조직으로부터 족부의 근육층까지 분포한다.2. 미분화간층직과 호산성 과립세포들이 초기 활성기의 소낭에 풍부하게 나타나기 시작하여 완숙기에는 거의 없어지는 것으로 보아, 이들은 생식소 및 생식세포형성과 발달에 영향을 공급하는 영향세포로 생각된다.3. 생식소발달, 생식세포형성과정, 조직분화과정 및 세포학적 특성에 따라, 이들의 생식주기를 초기 활성기, 완숙기, 부분 방출기, 방출 및 비활성기 등으로 구분할 수 있다. 4. 방란 및 방정은 수온 2$0^{\circ}C$정도되는 6월하순부터 시작되고, 주산란시기는 수온이 23-24$^{\circ}C$정도 되는 7-8월이며, 완숙란의 크기는 50-60$\mu\textrm{m}$이다.5. 비활성기는 9월에서 이듬해 4월까지 지속되는 비교적 긴 기간이며, 초기 활성기도 비교적 길어 1월에서 5월까지 지속되는 반면, 후기활성, 완숙 및 방출기는 비교적 짧아, 5월에서 8월까지 모두 완료된다.6. 비만도의 월별 변화는 생식소의 발달, 생식주기 및 수온과 밀접한 관계가 있다.7. 사용된 재료 433개체 중 1개체가 자웅동체현상을 나타내었다.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.1 no.1
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• pp.13-19
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• 1996

Toxicity of surface seawater in Ulsan Bay on a sea urchin, Hemicentrotus pulcherrimus was assessed to investigate the correlation between the concentrations of five heavy metals (Fe, Co, Cu, Cd, and Ni) and the impairments during the developmental stage of the sea urchin eggs. The tests during the six developmental stages of the eggs, are fertilization rate, cell 4, cell 4, polyspermic cleavage, permanent blastula and exogastrula. Highly positive correlations were found between the concentrations of Cu, Co and Ni and the toxicities on the eggs. Such tests will be useful as an indicator of seawater quality.

• Journal of The Korean Association For Science Education
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• v.36 no.2
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• pp.295-302
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• 2016

In this study, we investigated a learning progression focusing on $5^{th}$ to $9^{th}$ graders' performances with dissolution and solution concepts using the construct modeling approach. We designed a construct map describing hypothetical pathways of the concept development of dissolution and solution by analyzing both National Science Curricula and related studies. A conceptions test consisting of ordered multiple-choice items was developed and administered to 826 students. A revised construct map was derived from analyses of the results based on the partial credit model, a branch of polytomous item response theory. The sequence of dissolution and solution concepts presented in the current science curriculum was found to correspond with the learning progression of the students. However, the lower anchor, the concept of the homogeneity of particles in solution, and the factors affecting solubility were not consistent with the expected levels of the construct map. After revising the construct map, we proposed a learning progression for dissolution and solution concepts with five levels: Students of level 1 (the lower anchor) recognize the particles in the solution but misunderstand various concepts; Students of level 2 understand the homogeneity of particles in solution; Students of level 3 understand solubility and the conservation of particles during dissolution; Students of level 4 partially understand the interaction between particles; and Students of level 5 (the upper anchor) understand the interaction between particles and the factors affecting solubility.

• Journal of The Korean Association For Science Education
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• v.25 no.4
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• pp.472-479
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• 2005

The purpose of this study was to develop an inquiry-based professional development program for in-service secondary science teachers and to investigate it's application. The inquiry-based professional development program was reconstructed based on SSCS problem-solving model, which is composed of 4 stages of search, solve, create, and share. The 28 science teachers' understanding of the SSCS program were investigated as implementing the program. As a result of this study, 8 SSCS modules have developed as the science teachers have searched, solved, created, and shared various situated problems. The science teachers found themselves to have positive perception of SSCS program. The SSCS program was effective in changing the learners' teaching/learning attitude and to develop individual scientific thinking. To make the SSCS problem solving successful and more effective, both science teachers' professionalism and pedagogical knowledge for selecting topic as the levels of learner should be considered.

• Journal of The Korean Association For Science Education
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• v.34 no.8
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• pp.703-718
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• 2014

This study sought to investigate learning progressions for astronomical systems which synthesized the motion and structure of Earth, Earth-Moon system, solar system, and the universe. For this purpose we developed ordered multiple-choice items, applied them to elementary and middle school students, and provided validity evidence based on the consequence of assessment for interpretation of learning progressions. The study was conducted according to construct modeling approach. The results showed that the OMCs were appropriate for investigating learning progressions on astronomical systems, i.e., based on item fit analysis, students' responses to items were consistent with the measurement of Rasch model. Wright map analysis also represented that the assessment items were very effective in examining students' hypothetical pathways of development of understanding astronomical systems. At the lower anchor of the learning progression, while students perceived the change of location and direction of celestial bodies with only two-dimensional earth-based view, they failed to connect the locations of celestial bodies with Earth-Moon system model, and they could recognized simple patterns of planets in the solar system and milky way. At the intermediate levels, students interpreted celestial motion using the model of Earth rotation and revolution, Earth-Moon system, and solar system with space-based view, and they could also relate the elements of astronomical structures with the models. At the upper anchor, students showed the perspective change between space-based view and earth-based view, and applied it to celestial motion of astronomical systems, and they understood the correlation among sub-elements of astronomical systems and applied it to the system model.

• Journal of The Korean Association For Science Education
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• v.37 no.6
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• pp.1015-1023
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• 2017

The purpose of this study is to investigate the process of development of explanatory hypothesis being generated by middle school students and the factors that affect the process in water wave interference phenomena by analogy scaffolding. For this purpose, the processes on how explanatory hypotheses were generated, revised, and then elaborated by analogy scaffolding were investigated and analyzed. The subjects for the study were 60 eighth grades students in one middle school divided into 12 groups according to their cognitive level measured by GALT. The research findings are as follows: First, it was found that there is a regular pattern in development of explanatory hypothesis by students about water wave phenomenon; second, the cognitive level of the student affected apparently on the students' hypothesis development process, however, it was also observed that students with inferior cognitive level could form a scientific explanatory hypothesis in the second stage of the scaffolding; third, the analogy scaffolding actually helped the students in formulating hypothesis. In conclusion, analogical reasoning can be a meaningful and powerful strategy for secondary school students to formulate explanatory hypothesis.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.36 no.8
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• pp.839-847
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• 2012

Numerical simulations for channel flows with $Re_{\tau}$ = 180, 395 and 590 have been performed to investigate the hairpin packet formation process in wall-bounded turbulent flows. Using direct numerical simulation databases, the initial flow fields are given by the conditionally averaged flow field with the second quadrant event specified at the buffer layer. By tracking the initial vortex development, the change in the initial vortex to an ${\Omega}$-shaped vortex and th generation of a secondary hairpin vortex were found to occur with time scales based on the wall units. In addition, at the time when the initial vortex has grown to the channel center, the inclination angle of the hairpin vortex packet is approximately $12{\sim}14^{\circ}$, which is similar for all three Reynolds numbers. Finally, numerical simulations of the evolution of two adjacent hairpin vortices have been performed to examine the interaction between the adjacent vortex packets.

• Proceedings of the KGS Conference
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• 2002.05a
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• pp.17-22
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• 2002

이 연구는 한국 화전농업의 역사와 발전과정을 살펴보고, 화전의 분포와 그 요인을 알아보고자 한다. 또한 오대산 부근 지역을 선정하여 화전과 관련한 산지 개간과 촌락의 형성 과정을 야외 조사를 통하여 살펴보고자 하였다. 한국의 화전은 오랜 역사를 갖고 있으며 산림 감독이 소홀한 조선 후기에 와서 화전 면적이 급증, 일제시대에는 최전성기를 보여주었다. 오대산의 깊숙한 고산간지에까지 개척이 이루어진 것은 일제 초의 토지조사사업과 신품종 등 농업기술의 발달에 연유하였다. 일제강점기 초 평지농토에서 쫓겨난 수많은 농민들은 화전으로 농토를 개척할 수 있는 산림지로 이동하였고, 고산간지에서도 생육이 가능한 새로운 품종이나 기술이 보급된 덕분이었다. 이들에 의해 개척된 촌락은 대개 3~4대 정도의 역사를 갖는 씨족이 최고이며 조부대에 이주해온 씨족이 대부분이다. 즉 고산지에서의 산지 개척의 역사가 100년 정도에 불과하다. (요약 및 결론에서 발췌)

• Communications of Mathematical Education
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• v.18 no.2 s.19
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• pp.427-440
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• 2004

Freudenthal의 수학화 이론에 대한 지금까지의 대부분의 연구는 이론의 탐색에 집중하고 이에 따른 학습 지도 방안과 자료개발에만 역점을 두었던 것이 그 한계점으로 지적되어져 왔다. 이에 본 연구자는 실제 이 이론이 어떻게 학습 현장에 적용될 수 있는지에 대해 첫째, Freudenthal의 수학화에 의한 도형 지도에서 학생이 어떻게 수학화를 이루어 가는지를 조사하였고, 둘째, 학습의 주체자인 학생들의 능동적인 활동을 강조한 수학화 과정에서 교수의 주체자인 교사는 학생들의 수학화가 원만히 이루어지게 하기 위하여 어떤 역할을 수행하게 되는지를 중학교 1학년 학생을 대상으로 사례연구를 실시하여 조사하였다.

• Proceedings of the Korean Aquaculture Society Conference
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• 2003.10a
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• pp.60-60
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• 2003

릿테르개멍게는 척색동물문 해초강에 속하는 멍게류로서 고착생활을 하며, 보통 해조류나 히드라 등으로 덮여 있어 눈으로 식별하기가 어렵고, 생태 및 분류에 관한 연구만이 있을 뿐이다. 이 연구는 제주도 연안에 서식하는 릿테르개멍게의 번식생태에 대한 기초자료를 얻고자 배우자형성과정 및 생식소 발달 단계 등을 조직학적으로 조사하였다. 실험 재료는 제주도 용담 연안에서 2001년 11월부터 2003년 1월까지 매월 20개체씩 총 300개체를 채집하여 생식소의 조직학적 변화를 관찰하였다. 릿테르개멍게는 자웅동체로서 생식소는 체벽부에 붙어 있고, 성숙시기에 난소는 적색을, 정소는 유백색을 띠고 있다. 생식소와 체벽부를 포함해 절단된 조직표본에서 보면 외측체벽은 근섬유를 포함한 섬유성결합조직이 발달해 있고 여기에 이어진 방형의 난소낭과 그 주변부에 자리 잡고 있는 여러 개의 정소낭을 식별할 수 있었다. 생식소 발달 및 배우자형성과정, 월별 생식소변화를 토대로 생식주기를 구분하면 성장기 (3-5월),난황기 (5-7월), 성숙기 (7-11월), 방출기 (11-2월), 회복기 (1-3월)로 구분되었으며, 주 산란시기는 11-1월로, 연중 1회의 산란시기를 갖는다.