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손익 및 배당정보가 외부자금조달의 공시효과에 미치는 영향
최도성,이성효 한국재무관리학회 1994 財務管理硏究 Vol.11 No.2
This paper relates the valuation consequences of common-stock, convertible-debt and straight-debt offering announcements to the issuing firms' stock price performance in periods before the announcements. Similar to pervious studies on equity offering, we find that the announcement effects of security offerings, regardless of offering types, are negatively correlated with the short-term pre-offering stock returns. We show that the informational impact of the preceding earnings and dividend(E/D) announcements account for the previous findings of the negative correlation. We further report that security issues following $quot;good-news$quot; E/D announcements result in larger stock price declines than issues following $quot;bad-news$quot; E/D announcements. The finding is consistent with the hypothesis that the E/D information affects the investors' assessments of the firm's cash flow expectations and of the probability of external financing.
초등학교 자연과 ' 작은생물 ' 단원의 수업 실태 분석
최도성,김석중,남철우,최규식,김정길,한광래,송판섭,한효의 한국초등과학교육학회 2000 초등과학교육 Vol.19 No.1
The purpose of this study is to survey the instructional state of the unit 'Small Living Things' in the Elementary School Science. For this study, 100 teachers were surveyed on teaching-learning practices. More specifically, questions were asked on the degree of accomplishing instruction objectives, frequency of field. study, experimental preparation, alternative instructional methods, amount of preparation, availability of reference books for teachers and availability of information materials on the Kwangju region. Our results show that teachers find the objectives related to the collection of living things for class experiments and the task of growing and observing them the most difficult to accomplish. It was reported that 38% of teachers have actually conducted field trips. The obstacles listed in going out on field study range from lack of knowledge of appropriate places, lack of time, to safety concerns. The most difficult problem in teaching this unit was preparing proper instructional materials, regardless of teacher's gender, career, and interest. Most respondents let children provide the experimental subjects. Teachers with collection experience tend to provide for the experimental materials themselves. Our Analysis also reveals that more than 70% of the respondents do not have adequate knowledge of the species dealt with in the unit. Gender, career, and interest area of the teachers did not make any difference (p$lt;.05). In the case that proper experimental subjects have not been prepared, VTR, textbooks, and charts were reported as the most frequently used alternative instruction aids. The level of content and amount of knowledge contained in this unit were found to be appropriate. Information on instruction materials and experiment observation were obtained through the teaching manual or periodicals (58%), information materials on the region(20%), and fellow teachers (12%). Reference books for teachers and materials on the region are perceived to be inadequate in order of importance in the areas of preparation method, level-wise learning guide, experimental observation, and information on species covered in text. Overall, it was judged that the highest concern was with obtaining experimental materials, and teacher's reference books and materials on the region need to be reinforced to allow teachers to more fully utilize them. Development and distribution of proper instruction-learning materials to the children's level is also required.
최도성,강문주 韓國生物敎育學會 1992 생물교육 Vol.20 No.1
We carried out the analytical study on the teaching plants appearing in all the textbooks of the primary school of Korea, 1990. The results were summarized as follow: 1. Teaching plants of 222 species appeared in the textbooks of the primary school. The high level number of species were appeared in Korean language, Paractice, Society, Morality subject, and in sixth, fourth and fifth classes in turn. 2. The errors of plant name were discovered in the 26 species. 3. The classification system for plants in the primary school curriculum was based on the Eichler system. Teaching plants (excluded fungi) were classified to Crytogamae (13 species) and Phanerogamae (209 species). And Angiosperms were eoncretely dealt in the present curriculum of the primary school. 4. Because Eichler system does not show the phylogenetic relationship in the plant classification, we propose the modified system to be able to adopt in the primary school curriculum. 5. The number of plants appearing in nature subject as materials for experiment were 32 species. Their appearing frequencies were high in some plants, such as kidney bean, radish, corn, Spirogyra, and duckweed. We present exchangeable plants far them and reasons to that.
최도성,이성수 한국음향학회 2004 韓國音響學會誌 Vol.23 No.3
스피커 댐퍼의 재질에 따른 휨강도와 기하학적 요소인 주름의 반경 및 각 주름의 곡률반경으로 탄성계수를 결정하여 실험치와 비교하였다. 그 결과 댐퍼의 탄성은 휨강도에 비례하고 원형주름의 반경에는 반비례하며 주름의 곡률반경의 제곱에 반비례함을 알 수 있었다. 또, 댐퍼의 안쪽은 주름을 작게 만들고 바깥쪽은 주름을 크게 만든 변형 댐퍼로 스피커를 제작함으로서 고음부의 감도가 증가하면서도 저음부가 강화되는 소형 스피커를 만들 수 있었다. A decision of the modulus of elasticity is made by using the degree of bending strength of materials for loudspeaker damper and the radius of corrugation lines and the radius of curvature of each corrugation as a geometrical element. And it is compared with experimental measurements. As a result. the elasticity of damper is proportional to the degree of bending strength and inversely proportional to the radius of corrugation lines and inversely proportional to the square of the radius of curvature. We made a small loudspeaker using a modified damper which take the form of inner small curvature and outer large curvature of each corrugation. This loudspeaker have the increased sensitivity in high frequency and also in low frequency region.