가토 신동맥 평활근에서 Strontium의 Calcium 대행역할

장윤철(Chang, Yun-Cheol),전병화(Jeon, Byeong-Hwa),장석종(Chang, Seok-Jong) 대한생리학회 1990 대한생리학회지 Vol.24 No.2

The Ca²⁺-substitutional$</TEX> roles of strontium for the contractile processes were investigated in the rabbit renal artery. The contractions induced by either norepinephrine or high K⁺ in the condition which intra- and extracellular Ca²⁺ were replaced by Sr²⁺, i.e. Sr²⁺-mediated contractions, were dose-dependent. And then the maximal amplitude of contraction, as compared with Ca²⁺-mediated contraction, was about 50% in norepinephrine and about 70% in high K⁺. The Sr²⁺-mediated contractions were independent in the contraction by norepinephrine 10^-5M) but dependent in those by high K⁺(100 mM) on the extracellular Sr²⁺ concentration. Also Sr²⁺-mediated contractions induced by norepinephrine were observed in the Sr²⁺-free Tyrode s solution. The Sr²⁺-mediated contractions induced by either norepinephrine or high K⁺ were suppressed by verapamil, a Ca²⁺-channel blocker. By extracellular addition of Sr²⁺, the Ca²⁺-mediated contractions induced by norepinephrine 10^-5M) or 40 mM K⁺ were inhibited but those by high K⁺(100 mM) were increased. And the Sr²⁺-mediated contractions were increased by extracellular addition of Ca²⁺ but did not reach the level of Ca²⁺-mediated contraction. Therfore it is suggested that in the vascular smooth muscle of rabbit renal artery Sr²⁺ could enter the smooth muscle cells easily through the potential-operated calcium channel (POC) but not easily through the receptor-operated calcium channel (ROG), and Sr²⁺ might be stored in the intracellular Ca²⁺-binding site and released by NE and induced the contraction by a way of activating directly the contractile apparatus.

액면 분할의 단기성과 분석 연구

장윤철 ( Yun Cheol Chang ),신연수 ( Yeon Soo Shin ) 아시아.유럽미래학회 2012 유라시아연구 Vol.9 No.4

The opinion about stock split was clearly divided into two sides. Stock split is irrelevant to performance and cash flow in the market and it is nothing but increase the number of shares, so it could increase trading cost which adversely affect corporate performance. Meanwhile stock split could be recognized positive signal of managers and it could be expected to increase of dividend due to increased shares which affirmatively affect corporate performance. This study regard it as meaningful only to measure short-term performance and to suggest the effectiveness of stock split. This study measure of short-term performance after the date of split disclosure and execution about KOSPI 120 companies and KOSDAQ 186 companies. Short-term performance of stock split was analyzed by measuring of cumulative abnormal returns (CAR) by using the method of market model and Scholes-Williams model, GARCH, EGRACH model. The purpose of this study analyzed that the disclosure and execution of stock split have an effect on short-term performance in the Korean securities market. Managers want to trade to lower prices through a stock split, so that this could be predicted that individual investors rather than institutional investors can be induced into the market to increase information asymmetry in the market than ever before. Therefore, increase of these information asymmetries will increase the trading cost to reduce liquidity consequently. There exist several theories about disclosure effects of the stock split. First, the company``s internal information is provided to the market through a stock split (Signalling Hypothesis). Grinblatt, Masulis, Titman (1984), Lamoueux, Poon (1987), Brennan, Copeland (1988). Second, the lower of the trading price of the shares is to attract new investors in the securities market through a stock split(Trading Range Hypothesis), Copeland (1979), McNichols, Dravid (1990). Third, changing the tick size of each investor through a stock split is to minimize transaction costs (Minimum fluctuation hypothesis), Angel (1997). Fourth, institutional investors through a stock split is to produce better information(Information production hypothesis) Brennan, Hughes (1991). The result of an empirical analysis on the short-term performance of the stock split shows as follows. First, short-term performance of the KOSPI market after the stock split showed positive performance at market model and the market model + SW, Market Model + GARCH model, and the market model + EGARCH model. However, the performance showed the decrease in the market-adjusted model of execution day. Namely, the cumulative abnormal return at the period of window (0, +30) showed 20.25% in the market model 20.08% in the market model+SW model, 11.61% in the market Model+GARCH model, 12.95% in the market model+EGARCH model. The market adjusted model between Disclosure day and execution day appeared very different result in comparison with existing analysis. The cumulative abnormal return of market-adjusted model of disclosure day showed 2.32% at the period of window (0, +10), while -16.05%at the period of window (0, +30). The cumulative abnormal return of market-adjusted model of execution day almost showed statistically significant negative return at the period of window (0, +30). Therefore, the short-term performance of the stock split was not shown. Second, short-term performance of the KOSDAQ market after the stock split also showed positive performance at market model and the market model + SW, Market Model + GARCH model, and the market model + EGARCH model. However, the performance was decreased in the market-adjusted model of execution day. Namely, the cumulative abnormal return at the period of window (0, +30) showed 0.18% in the market model, 0.19%in the market model+SWmodel, 0.20%in the market Model+GARCH model, 0.21% in the market model+EGARCH model. The market adjusted model between Disclosure day and execution day appeared very different result from existing analysis. The cumulative abnormal return of market-adjusted model of disclosure day showed 0.06% at the period of window (0, +10), while 0.26% at the period of window (0, +30). The cumulative abnormal return of market-adjusted model of execution day almost showed 0%at the period of window (0, +1), -0.01%at the period of window (0, +10), -0.03% at the period of window (0, +30). The cumulative abnormal return of market-adjusted model of execution day almost showed statistically significant weak negative return at all period within window (0, +30). Therefore, the short-term performance of the stock split was shown weakly. The short-term performance of the stock split is invisible in KOSPI market, but appears weakly in KOSDAQ market through various verification model. The short-term performance analysis of stock split could be seen to provide as an new indicator to investors who want short-term investments in the KOSPI and KOSDAQ market. The stock split have an effect on increasing liquidity in the market, and the value for the stock split is already reflected in the share price in the market due to a variety of information and disclosure system to investors. KOSDAQ market also got the conclusion that the share price that reflects the increase in trading volume and stock price due to the stock split which were accepted as a favorable factor to investors have synergistic effect of the value of corporate on stock price.

악성 복수 및 홍수에 대한 OK-432의 효과

이창수(Chang-Su Lee),장윤철(Yoon-Cheol Jang),이수환(Soo-Whan Lee),이찬영(Chan-Young  Lee) 대한외과학회 1988 Annals of Surgical Treatment and Research Vol.34 No.3

Diazepam이 신 혈류역학에 미치는 영향

장윤철,김광진 충남대학교 의과대학 지역사회의학연구소 1986 충남의대잡지 Vol.13 No.1

This investigation was attempted to evaluate the effect of diazepam on the renal function of rabbits. Rabbits were divided into two groups: injection(5mg) and infusion(10mg/hr). Urine flow rate, renal plasma flow, glomerular filtration rate. electrolytes and osmolar clearance, tubular reabsorption and urinary excretion rate were measured in the period of control and after diazepam administration. The results obtained were summarized as follows: 1. Renal plasma flow(RPF) and glomerular filtration rates(GFR) were significantly decreased after diazepam administrated. Correlation coefficient between RPF and GFR was 0.911 and it was statistically significant. 2. Urine flow rates were reduced after diazepam administrated in both groups. And relationship between urine flow rate and GFR or RPF were statistically significant. 3. Tubular reabsorption of potassium was reduced significantly, but urinary excretion was constant. 4. Negative free water clearance was decreased after diazepam administered in both groups. From the above results, it was suggested that diazepam reduce the urine flow due to decreased renal hemdynamics and also modified potassium and water reabsorption in the renal tubular cells.

하부장관 출혈의 치료

이봉화,장윤철,우제홍,이찬영 대한대장항문학회 1987 Annals of Coloproctolgy Vol.3 No.1

드로잉 금형에 있어서 비드의 영향

고관영,최원정,조재희,명노훈,이창수,최병용,허주환,최창권,장종훈,장윤철,박기용 울산과학대학 2001 연구논문집 Vol.28 No.1

본 연구는 자체 제작한 다이 측 비드가 설치 된 드로잉 금형을 이용하여 SUS 304, 6:4 황동 판재를 드로잉 가공하여 생산된 제품의 치수변형 특성을, 비드를 설치하지 않은 자유 드로잉 하여 얻은 제품과 비교하였다. SUS 304 판재의 경우, 비드를 설치하여 드로잉 한 경우는 늘어난 길이의 변화가 연속적으로 증가하고 있고, 비드를 설치하지 않은 경우는 마지막 부분에서 다시 회복상태를 보였다. 그 원인은 드로잉 비드로 인하여 적정량의 유입으로 일정 비율로 늘어난 것이라고 볼 수 있다. 6:4 황동 판재의 경우는 비드를 설치한 경우의 치수 변형값이 비드를 설치하지 않은 경우보다 안정함을 보여주었다. In this research, properties of SUS 304 and 6:4 brass products produced by die bead-drawing mold were compared with those of products drawed without bead. In the case of bead-SUS-plate, variation of incremental length progressively increases, while, in the case of no bead-SUS-plate, recovery appeared at the final-part. The reason of this difference is considered as proper insert of metal-plate on the basis of bead. Bead-6:4 brass-plate showed more stable data than no-bead die case although it did not show recovery in final-part.