단일과대하중하에서 피로균열진전지연거동 및 지연수명의 확률론적 해석

심동석,김정규,Shim, Dong-Suk,Kim, Jung-Kyu 대한기계학회 1999 大韓機械學會論文集A Vol.23 No.7

In this study, to investigate the fatigue crack retardation behavior and the variability of retardation cycles, fatigue crack growth tests were conducted on 7075-T6 aluminum alloy under single tensile overload. A retardation coefficient, D was introduced to describe fatigue crack retardation behavior and a random variable, Z to describe the variability of fatigue crack growth. The retardation coefficient was separately formulated according to retardation behavior which is composed of delayed retardation part and retardation part. The random variable, Z was evaluated from experimental data which was obtained from fatigue crack growth tests under constant amplitude load. Using these variables, a probabilistic model was developed on the basis of the modified Forman's equation, and retardation behavior and cycles were predicted under certain overload condition. The predicted retardation curve well agrees with the trend of experimental crack retardation behavior. And this model well predicts the scatter of experimental retardation cycles.

최고경영자 교체공시와 주가반응

심동석(Dong Suk Shim) 한국경영학회 2000 經營學硏究 Vol.29 No.4

The objectives of this study are to examine abnormal stock returns associated with announcements of top management changes and to determine the factors that explain abnormal stock returns. This study is conducted using a standard event study methodology and multiple regression analysis. The results of this study can be summarized as follows: First, the announcements that predecessor is not employed as top management by another firm are associated with significantly negative abnormal stock returns. An average abnormal return for two day announcement period and ten trading days starting from day -1 to day +8 are respectively -0.880%(t=-2.921) and -1.746%(t=-3.179) which are significantly different from zero at 0.01 level. This result suggests that announcements that predecessor is not employed as top management by another firm convey bad news to the market that the firm`s performance was worse than the market has realized. However, the announcements that predecessor is employed as top management are associated with insignificant abnormal stock returns. This result suggests that announcements that predecessor is employed as top management do not convey bad news to the market. Second, cumulative abnormal stock returns are positively related to the relative size of predecessor`s performance to industry average, firm size and dummy variable that represents the disposition of predecessor. However the dummy variables that represent the origin and ability of successor are not related to cumulative abnormal stock returns. This result suggests the origin and ability of successor do not have the information contents in Korea stock market.

시설투자공시가 주주의 부에 미치는 영향에 관한 연구

심동석(Dong Suk Shim) 한국증권학회 1995 Asia-Pacific Journal of Financial Studies Vol.18 No.1

창업주의 사망과 기업가치의 관련성

심동석(Dong Suk Shim) 한국경영학회 1998 經營學硏究 Vol.27 No.4

The purposes of this study are to examine abnormal stock returns associated with announcements of founder deaths, and to determine whether the abnormal stock returns can be explained by firm characteristics variables. Both traditional event study method and multiple regression analysis have been employed in order to answer this question. The findings of empirical study can be summarized as follows: First, on average the announcements of founder deaths is not associated with significant abnormal stock returns. However, the announcements of founder deaths for subsample with low debt ratio is associated with significant positive abnormal stock returns. The announcements of founder deaths for subsample with high debt ratio is associated with significant negative abnormal stock returns. Second, DEBT and Ability have significantly negative relationship with cumulative abnormal stock returns, whereas TA and Time have positive relationship with cumulative abnormal stock returns.

균열진전에 대한 쇼트피닝 효과

심동석(DONG-SUK SHIM),이승호(SEUNG-Ho LEE),이명호(MYUNG-Ho LEE) 한국해양공학회 2004 韓國海洋工學會誌 Vol.18 No.6

In this study, to investigate the effects of shot peening on crack growth behavior, crack growth tests are conducted on spring steels and shot peened cracks. The probabilistic crack growth equation, which can represemt the sigmoidal crack growth behavior as recently reported by Kim and Shim, is used to evaluate the experimental results. The results show that fatigue cracks grows slower in the shot peened specimen than in the unpeened ond, due to the compressive residual stress occurring on the specimen surface. In the case of the shot peened specimen, the initial stress intensity factor range and the fracture toughness is higher than the non-peened specimen because the compressive residual stress affects crack growth and fracture of the specimen.

비행하중파형의 축소가 균열진전에 미치는 영향

심동석 ( Dong-suk Shim ),이승호 ( Seoung-ho Lee ) 한국고등직업교육학회 2003 한국고등직업교육학회논문집 Vol.4 No.4

In this study, to investigate the effects of omitting low-amplitude cycles from a flight-simulation loading, crack growth tests are conducted on 2124-T851 aluminum alloy specimens. Three test spectra are generated by omitting small load ranges. The crack growth test results are compared with the data obtained from the flight-simulation loading. The experimental results show that the ranges equal to or smaller than 5% of the maximum load do not contribute to crack growth behavior because these are below the initial stress intensity factor range. Omitting these from the flight-simulation loading, test time can be reduced by 54%.

시설투자공시가 주주의 부에 미치는 영향에 관한 연구

심동석(Dong Suk Shim) 한국증권학회 1995 한국증권학회지 Vol.18 No.1

채무보증공시의 정보효과

심동석(Dong Suk Shim) 한국경영학회 1996 經營學硏究 Vol.25 No.2

It is not uncommon in the arrangement of a loan to include a guarantee of the loan by the third party. Examples are guarantees by a parent company of the loans made to its subsidiaries. The purposes of this study are to examine abnormal stock returns of the guarantor firms and guarantee firms in response to announcements of loan guarantee, and to find the factors that determine the abnormal stock returns. The findings of this study can be summarized as follows: (1) The CARs(AD-30∼AD) of guarantor and guarantee firms that do not consist of top thirty large business group are -3.23% and -11.08%, respectively. Both CARs are found to be statistically significant with t-statistic of -1.98 and -3.12, respectively. But no significant CARs(AD-30∼AD) are detected for guarantor and guarantee firms that consist of top thirty large business group. This evidence indicates announcement of loan guarantees by firms that do not consist of top thirty large business group covey negative information to the capital market. (2) Results of regression run reveal that the magnitude of CARs of guarantor firms is positively correlated with the variables that are suggested by leverage hypothesis and that of guarantee firms is negatively correlated with book-value debt-equity ratio.

최고경영자 교체연도의 이익조정

심동석(Shim Dong-suk),안창호(Ahn Chang-ho) 한국국제회계학회 2015 국제회계연구 Vol.0 No.64

전체표본을 대상으로 최고경영자 교체연도의 이익조정 현상을 분석한 국내연구는 두 편으로 매우 적어 그 연구결과를 일반화하기가 어려운 실정이다. 전체표본을 전임경영자 퇴임유형과 신임경영자 영입유형으로 각각 구분한 소표본을 대상으로 이익조정 현상을 분석한 국내연구결과는 서로 일치하지 않았다. 따라서 본 연구는 2000년부터 2005년 사이에 표본으로 선정된 167개 기업을 대상으로 최고경영자 교체연도의 이익조정 현상을 분석하였다. 분석결과, 전체표본에 대한 성과대응 재량적 발생액은 –0.024(t=-1.29)로 유의하지 않게 나타나 한국적 기업환경에서 신임경영자의 big bath에 대한 증거는 발견되지 않았다. 이러한 분석결과는 전체표본을 대상으로 big bath 현상을 분석한 국내외 모든 선행연구결과와 상반되는 것이다. 이는 한국에서 일부 신임경영자는 유리한 자금조달과 신용등급을 향상시키기 위하여 이익을 상향조정할 수도 있다는 것을 나타내고 있다. 다음으로 전체표본을 신임경영자의 영입유형에 따라 외부영입과 내부승진으로 구분한 두 소표본의 성과대응 재량적 발생액은 1%에서 유의한 –0.092(t=-2.70)와 0.013(t=0.22)으로 각각 나타났다. 또한 두 소표본간의 성과대응 재량적 발생액 평균 간의 차이가 –0.105(t=-2.74)로 1% 수준에서 유의하였다. 마지막으로 전체표본을 전임경영자 퇴임유형과 신임경영자 영입유형을 함께 사용하여 비자발교체/외부영입 소표본과 자발교체/외부영입 소표본을 대상으로 측정한 성과대응 재량적 발생액은 5%에서 유의한 –0.088(t=-2.22)과 –0.086(t=-1.74)으로 각각 나타났다. 그러나 두 소표본간의 성과대응 재량적 발생액 평균간의 차이는 –0.002(t=-0.13)로 유의하지 않았다. 본 연구의 결과는 외부투자자들이 최고경영자 교체 후에 공표된 이익정보를 바탕으로 미래이익을 예측할 때 신임경영자의 영입유형에 따른 이익조정 현상을 신중하게 감안할 필요가 있음을 시사한다. This study examines whether the incoming CEO is to make a big bath at the transition year associated with CEO turnover using performance-matched discretionary accrual measures. With 167 CEO changes data collected over 2000-2005 periods from Korean listed companies. We examine the empirical evidence on earning management associated with CEO turnover. The empirical findings are summarized as follows: First, using full sample, we find evidence that the incoming CEO is not likely to take a big bath at the transition year. This finding is not consistent with that in all prior researches. Also this finding suggests that all the incoming CEOs do not make opportunistic earning management. Second, we examines whether types of incoming CEO(internal promotion vs external recruitment) affect the level of earning management. We find evidence that externally recruited CEO is more likely to deflate earnings in order to make a big bath. Finally, when incoming CEO is externally recruited, we also examines whether types of departing CEO(voluntarily turnover vs forced turnover) affect the level of earning management. We do not find any significant differences in terms of level of earnings management between samples having voluntarily vs forced CEO turnover.

균열 특성 개선을 위한 2단 쇼트피닝 가공

이승호,심동석,Lee, Seoung-Ho,Shim, Dong-Suk 한국기계가공학회 2003 한국기계가공학회지 Vol.2 No.4

In this study, to investigate the effects of 2-step shot peening at the surface of spring steel, crack growth tests are conducted on spring steel and shot peened specimens. And then the residual stresses and fractographs are examined. The crack growth equation that can describe the whole crack growth behavior is used to evaluate the experiment results. The results show that fatigue crack glows slowly in the shot peened specimen than in the unpeened. And in the case of the 2-step shot peened specimen the initial stress intensity factor range and the fracture toughness is higher than the unpeened specimen due to the compressive residual stress. Fractographs show that the compressive residual stress of the surface suppress the fatigue crack opening and consequently slow crack growth rates.