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이계원 조선대학교 지역사회발전연구원 2003 地域發展硏究 Vol.8 No.1
This study is purposed to test the market efficiency of KOSDAQ which present the adequate information to the investor in the second board market-I examine the impact of main board listing information on the stock price of KOSDAQ. I find that stock returns as measured by CAR are significantly increasing from disclosure day, which listing on KSE, to the after 30 business day. The positive correlation found between stock returns and listing announcement is also supportive of the view that KOSDAQ market has a lower degree of market efficiency than KSE. My findings can be summarized as follows. First, I find that listing on KSE is a good news for the investor in KOSDAQ. Second, CAR of listing firms from KOSDAQ is higher than the firms without KOSDAQ after listing day.
부채비율이 주식수익률과 주가순자산 비율에 미치는 영향에 관한 연구 : 외환위기 부채비율 200%를 중심으로 Empirical Evidence
이계원 한국세무회계학회 2004 세무회계연구 Vol.15 No.-
본 연구는 자본구조(부채비율)가 기업가치의 대리변수라 할 수 있는 초과수익률과 주가순자산비율에 영향을 미치는지의 여부를 검증한다. 특히, 외환위기 이후 IMF의 요구에 따른 부채비율 200%이하라는 목표를 달성한 기업들에서 자본구조와 기업가치간에 어떤 유의적인 관련성이 있는지를 살펴보고자 한다. 즉, 부채비율 200%를 최적자본구조의 기준점이 될 수 있을 것인지를 살피기 위해, 외환위기 이전 2년과 이후 3년 동안인 1996년 1월부터 2001년 12월까지를 표본기간으로 선정하고, 표본기업은 상장기업 중 결산일이 12월 31일인 제조업을 대상으로 536개 기업(5년간 누적 기업수임)을 선정하였다. 실증분석 결과, 외환위기 이후 정부가 정책목표로 설정한 부채비율 200%이하 의무달성 5대 재벌기업들은 물론, 재벌기업과 비재벌기업을 분류하여 분석한 결과에서도 자본구조가 기업가치에 유의적인 영향을 미치지 않는 것으로 나타났다. 결국 부채비율 200%가 기업가치를 극대화하기 위한 최적자본구조로서 의미를 지니지 못하였다고 판단된다. 이는 비록 IMF의 요구에 따른 정부의 부채비율 200%이하 정책으로서 단기적으로는 기업의 위험축소라는 나름대로의 긍정적인면이 있지만, 부채비율 축소로 인하여 기업가치가 달라지지 않았다면 기업으로 하여금 중·장기적인 새로운 투자를 할 수 있는 기회를 가지지 못하게 하는데 일조를 한 것으로 보인다.
방사선 조사 후 흰쥐 넙다리곧은근에서 나타나는 미세구조의 변화에 Allopurinol과 Dimethylthiourea가 미치는 영향에 대한 연구
김민호,이계훈,백두진 한양대학교 의과대학 1999 한양의대 학술지 Vol.19 No.2
The purpose of this study was to investigate the ultrastructural changes of skeletal muscle and the effects of pretreatment of allopurinol, an inhibitor of xanthine pxidase and dimethylthiourea (DMTU), an effective scavenger of hydroxyl radicals in the rats after local exposure to irradiation. A total of 90 healthy Sprague-Dawley rats weighing from 200 g to 250 g were divided into two groups, control and experimental. And then the experimental group was divided into 3 groups. The first group was without pretreatment. The second was allopurinol pretreated group and the third was DMTU pretreated group. The allopurinol pretreated group was administered with 50 mg/kg of allopurinol once a day for 2 days and one hour before the irradiation. The DMTU pretreated group was administered with 500 mg/kg of DMTU one hour before the irradiation. Under urethane (1.15 g/kg, IP) anesthesia, 30Gy irradiation by PICKER-C9 Cobalt-60 teletherapy unit was done. Rectus femoris muscles were obtained after one day, 3 day, 7 day, 14 day and 28 day. Specimens were sliced into 1㎣ and prepared by routine methods for electron microscopic examination. All preparations were stained with uranyl acetate and lead citrate, and then observed with Hitachi-600 transmission electron microscope. The results were as follows. 1. In the post-irradiation rat without pretreatment, the ultrastructural changes of muscle fiber such as myofibrillolysis, disorganization of Z-line, irregular M-line, decreased glycogen particles were observed. The degenerative changes progressed until 14 days post-irradiation. 2. In the post-irradiation rat with pretreatment of allopurinol, the changes were not severe compared to that of the group without pretreatment. The degenerative changes were seen until 14 day post-irradiation but regenerating muscle fiber seen at 28 day post-irradiation. 3. In post-irradiation rat with pretreatment of DMTU, there were minimal changes of ultra-structure of muscle fiber in 1 day, 3 day, and 7 day post-irradiation. Especially, recovery of the number of glycogen particles in 7 day was different from the other groups of same day post-irradiation. These results suggest that the allopurinol and DMTU attenuate the ultrastructural changes of skeletal muscles of rat after x-ray irradiation. Especially, the effects were more marked in the group with pretreatment of DMTU.