터보히트펌프의 선형 안정성 해석

박정찬(Jung Chan Park),김길영(Kil Young Kim),정진희(Jinhee Jeong),송성진(Seung Jin Song) 한국유체기계학회 2011 한국유체기계학회 학술대회 논문집 Vol.2011 No.11

국내 지반침하사고 원인에 영향을 미치는 요인에 대한 민감도 분석

박정찬 ( Park Jung-chan ),이은미 ( Lee Eun-mi ) 한국구조물진단유지관리공학회 2023 한국구조물진단유지관리공학회 학술발표대회 논문집 Vol.27 No.1

본 연구는 국내 지반침하사고의 발생과 관련된 요인들에 민감도 분석을 통해 국내 지반침하사고에 영향을 미치는 요인에 대하여 분석을 실시하였다. 국내 지반침하사고에 영향을 미치는 요인은 노후화된 상 · 하수관로 및 다짐(되메우기) 불량이 침하사고에 미치는 영향력이 높았으며, 주요 침하원인인 상 · 하수관 손상, 다짐(되메우기)불량에 의한 지반침하사고는 특히 집중호우 시기(6~8월)에 집중되므로 주요 지반침하사고 원인에 강수량이 큰 영향을 미치는 인자로 판단된다.

암반의 3차원 불연속균열망(DFN)에 관한 연구 및 민감도분석

박정찬(Jung Chan Park),박승훈(Seung Hun Park),김하영(Ha Yung Kim),김건영(Geon-Young Kim),권상기(Sangki Kwon) 한국암반공학회 2015 터널과지하공간 Vol.25 No.4

기업지배구조가 주식가격 결정의 효율성에 미치는 영향에 관한 연구

정찬식(Chan Shik Jung),박경서(Kyung Suh Park) 한국증권학회 2020 한국증권학회지 Vol.49 No.1

본 연구는 기업지배구조가 좋을수록 과연 주식가격결정의 효율성이 향상되는지 실증적으로 규명하고 있다. 주식가격결정의 효율성 측정을 위한 대용변수로서, 분산비율(variance ratio), Hou and Moskowits(2005)이 제안한 가격결정 비효율성 지표, Hurst 지수(Hurst, 1951)를 종속변수로 사용한다. 실증분석 결과, 기업지배구조가 우수할수록 분산비율(variance ratio)은 더욱 1에 접근하였고, 가격결정의 지연 정도는 감소하였으며, Hurst 지수는 random walk을 나타내는 0.5 값에 더욱 근접하였다. 끝으로, 강건성 분석을 위해 고유위험(idiosyncratic volatility), 왜도(skewness)를 종속변수로 사용한 패널분석 결과, 기업지배구조가 양호할수록 고유위험이 감소하여 주가의 안정성이 증가되었고, 왜도가 감소하여 복권성향(lottery)의 투자가 감소하였다. 한편, 이처럼 좋은 기업지배구조가 주식가격 결정에 미치는 긍정적인 영향은, 특히 “주주권리보호”가 잘되어 있는 경우에 더욱 성립하였다. 이러한 결과들은 기존의 좋은 기업지배구조의 필요성을 주장하는 일련의 연구들과 맥을 같이 한다. This study investigates whether better corporate governance enhances the efficiency of stock pricing in the Korean stock market. The variance ratio (Lo and MacKinlay, 1988) is set as a proxy variable for the efficiency of stock pricing. Moreover, the degree of delayed stock pricing (Hou and Moskowits, 2005) is used as a proxy for the inefficiency of stock pricing. In addition, another measure of delayed stock pricing (Hou and Moskowits, 2005) is used as an additional proxy. Moreover, the Hurst Index, representative of the efficiency of stock pricing, is also used. According to the empirical investigation, better corporate governance drives the variance ratio to one (unity), reduces the degree of delay in stock pricing, and leads to a Hurst Index of 0.5, which represents the random walk process of the stock returns. Finally, for robustness checks, idiosyncratic volatility and skewness are set as dependent variables. The empirical results show that better governance reduces the idiosyncratic volatility and the skewness of individual stock returns. These findings indicate that better corporate governance enhances stock pricing efficiency. These results are therefore linked to the previous literature that argues that good governance should be set up necessarily.

종업원지주제도(ESOP) 도입을 통한 종업원의 영향력 강화가 기업경영과 기업가치에 미치는 영향

박경서 ( Kyung Suh Park ),정찬식 ( Chan Shik Jung ) 한국금융학회 2010 금융연구 Vol.24 No.1

본 연구는 국내기업에 종업원지주제도(ESOP)가 도입됨에 따라 종업원이 주주로서의 경제적 유인을 갖게 될 경우 근로자로서의 고정적 청구권(fixed claim)과 주주로서의 잔여적 청구권(residual claim)이 기업경영에 어떠한 교차적(interactive) 영향을 미치는 가를 분석하고 있다. 실증분석결과 종업원지주제도의 도입에도 불구하고 종업원은 주주로서의 경제적 유인보다는 근로자로서의 경제적 유인이 보다 강하게 작용하는 것으로 나타난다. 특히 종업원이 일정수준 이상의 주식을 보유하고 있거나 지배주주가 존재하지 않는 분산된 소유구조를 가진 기업의 경우, 종업원이 기업가치에 부정적인 영향을 미치는 정도가 더욱 큰 것으로 나타난다. 이는 종업원의 주주화가 기업가치에 오히려 부정적 요인으로 작용할 수 있으며 그 정도가 전문경영자 체제하에서 더욱 심각할 수 있음을 보여주고 있다. This paper analyzes the effect of the introduction of ESOPs on the management of Korean companies listed on the Korea Stock Exchange and on their firm values through an interactive dynamics with labor unions. One main objective of ESOPs is to lessen the conflicts of interests between the shareholders and the employees of a company by aligning their economic incentives. However, the paper sets up a hypothesis that ESOP might be exploited to strengthen the interest of employees as fixed wage earners by taking advantage of their voting rights to participate in corporate management, thus leading to more conflicts of interests with shareholders rather than aligning the interest of employees with that of shareholders. It is generally true that not many countries legally allow employees to officially participate in the management of their companies. Germany is one exception where the representatives of labor unions sit on the supervisory board of directors under its two-tier board system. One main reason for employees not to be allowed to participate in corporate managements would be due to their differential economic incentives from those of shareholders: Employees` main economic compensations are salaries which are mostly of fixed components while shareholders benefit from increasing revenues of their companies. This implies that shareholders have a strong incentive to take risk in their business decisions while employees would not do so as long as operating income exceeds their wage level. However, it is also a fact that employees do exercise some influence on the management of their companies and many existing literatures confirm such influence. The purpose of the paper is to empirically check such a possibility in Korean companies. Previous studies on the issue have approached the subject by analyzing the effect of labor participation or the introduction of ESOPs on corporate management separately, and have not considered their combined effect. We extend the existing research by analyzing whether the effect of labor participation in corporate management would be affected by the introduction of ESOPs in Korean companies. We expect that stronger labor unions would lead to lower investments in R&Ds, lower sales growth rates, lower dividend payout ratios, and lower firm values measured by Tobin`s Q. Strong labor unions would be negatively correlated with even employment growth rates since they would want to protect their vested interests at the sacrifice of future employees. On the other hand, we conjecture that ESOPs would be positively correlated with those variables since in theory they would align the incentives of employees with those of shareholders. However, we also conjecture the opposite since there is a very high chance that ESOPs are exploited as a channel for employees to officially participate in the management of their companies and strengthen the fixed component of their economic compensation. Especially, when the ownership structure is dispersed widely and there is no controlling shareholder so that a professional group of managers are in charge of the management, then the latter might be in a position to secure the support of employees to defend their control and therefore might be willing to succumb to the requests of employees in corporate decision making. The empirical analyses using the fixed effect panel model show that the introduction of ESOP negatively affects firm values, and that labor unions have negative effects on corporate behaviors and firm values. We also find that the negative effects of labor unions are stronger when there exists no controlling shareholder. Such results imply that, contrary to its original objective, ESOPs may not work to align the incentives of shareholders and employees, but rather strengthen the fixed claims of employees. It also implies that existence of a controlling shareholder can have a positive effect on the management of a company through his counter balancing role against the self interested demand of employees.

Can investor heterogeneity be useful in explaining the cross-section of average stock returns in emerging markets?

정찬식 ( Chan Shik Jung ),이동욱 ( Dong Wook Lee ),박경서 ( Kyung Suh Park ) 한국증권학회 2008 한국증권학회 발표논문집 Vol.2008 No.1

투자자는 지배주주가 이번 여름에 할 일을 알고 있다

박경서(Kung Suh Park),정찬식(Chan Shik Jung),김선민(Sun Min Kim) 한국증권학회 2018 한국증권학회지 Vol.47 No.5

동일 기업집단에 속한 계열사 간 합병은 지배주주가 동일하다는 점에서 합병 조건이 지배주주일가에게 유리하게 결정될 가능성이 있다. 본 연구는 국내 대규모기업집단에 속한 기업들 간의 합병공시 이전 장기간의 주가움직임을 분석한 결과 지배주주 지분율이 높을수록 또는 두 회사의 지배주주 지분율 차이가 양(음)으로 클수록 주식수익률이 유의하게 증가(감소)하는 현상을 확인하고 있다. 이러한 현상은 해당 회사의 상품시장에서의 경쟁이 취약할수록 더욱 확대되는 것으로 나타났으며, 동일기업집단 소속이 아닌 독립된 상장사 간의 합병에서는 관찰되지 않았다. 이러한 실증분석 결과는 계열사간 합병이 지배주주에게 유리한 시점에 결정되고 있으며, 주식시장의 투자자들은 사전에 이를 예상하고 주가에 반영하는 자기실현적 투자행태를 보이고 있는 것으로 해석할 수 있다. 또한 상장사 간 합병의 경우 주식교환비율의 결정시 시가(market price) 만을 사용하도록 제한하고 있는 국내의 합병관련제도의 보완이 필요함을 시사한다. In the case of affiliated mergers, which involves a merger between affiliated firms within a business group, there is a possibility that controlling shareholders who can exercise influence on the managers of both firms, may benefit from favorable terms of contracts for the firm where he owns more shares. This study analyzes the long-term stock returns before merger announcements comparing both affiliated mergers and independent mergers. We find that both the cumulative abnormal returns (CAR) and the buy-and-hold returns (BHAR) with matching firm analyses are positively correlated with the ownership of the controlling shareholders, and also with the difference between their ownerships on both firms in the case of affiliated mergers, while we don’t observe such phenomena in the case of mergers between independent firms. We also find the positive correlations are more significant for firms with weak product market competition or poor corporate governance. These empirical results imply that stock investors expect that affiliated mergers would be conducted in favor of controlling shareholders, and such an expectation is reflected in the stock prices of the firms involved as a self-fulfilling phenomenon. The study also suggests that the current law that specifies the use of stock market prices in deciding the stock exchange ratio between merging firms needs a review as the rule can be justified only when stock market prices are fair and are not compromised

교육용 로봇 ‘SILBOT Ⅱ’의 얼굴 구동 메커니즘

정찬열(Chan-Yul Jung),오경균(Kyung-Geune Oh),박신석(Shin-suk Park),김승종(Seung-Jong Kim) 대한기계학회 2010 대한기계학회 춘추학술대회 Vol.2010 No.11

This paper introduces a face driving mechanism of wheel-base mobile robot, Silbot Ⅱ, which is developed for English education. In the design of the robot face, two important points should be considered: one is that Silbot Ⅱ shows a cute and friendly image because it deals with children or old persons, and the other is that it should have a compact and light structure. For the former, Silbot Ⅱ was designed to have a spherical hard-skin face with big eyes and small lips. But, such a design results in making the compact mechanism difficult. In this paper, a face mechanism of Silbot Ⅱ is proposed, which is compact and modularized so as to avoid the interference inside and to facilitate the repair or maintenance. Silbot Ⅱ is currently playing an active part in teaching English to old persons in Masan Senior Welfare Center.

지배주주 지분율이 저축은행의 고위험 추구 행태에 미치는 영향에 관한 연구

박경서(Kyung Suh Park),정찬식(Chan Shik Jung) 한국증권학회 2015 한국증권학회지 Vol.44 No.5

본 연구는 지배주주 지분율이 저축은행의 위험추구(risk-taking)에 어떠한 영향을 미치는지를 실증적으로 고찰한다. Agrawal and Mandelker(1987)에 의하면, 경영자가 자신이 경영하고 있는기업의 주식을 상당 부분(large stock) 보유하고 있을 경우, 주식보유로 인한 위험추구 유인이 인적자본(human capital)의 감소효과를 상쇄하고 남아, 경영자 지분율이 증가할수록 경영자는 기업의 위험을 더욱 증가시킬 유인이 존재한다. 본 연구에서는 이들의 연구를 연장하여, 국내 저축은행의 경우 지배주주 지분율이 높을수록 지배주주가 저축은행의 위험을 더욱 증가시킬 것인지, 아니면 감소시킬 것인지 실증적으로 규명한다. 분석 결과, 지배주주 지분율이 증가할수록 저축은행은 고위험을 추구하였다. 구체적으로, 지배주주지분율이 높을수록 저축은행의 위험회피도를 나타내는 Z-Score가 감소하였고, 자산대비 예금액비율로 측정된 자본건전성이 악화되었으며, 고위험 대출에 해당되는 PF-대출이 증가하였다. 그 결과ROA의 변동성 및 자기자본 비용의 변동성과 타인자본 비용의 변동성으로 측정되는 저축은행의 위험수준이 모두 증가하였다. 요컨대, 저축은행의 고위험 추구 및 모험 경영은 특히 지배주주 지분율이 높은 은행의 경우 더욱심화될 수 있다는 점에서 학문적, 정책적 함의를 갖는다. This study empirically investigates the relationship between controlling shareholders’ ownership and the risk-taking behaviors of savings banks in Korea. According to Agrawal and Mandelker (1987), the large stock holdings of managers tend to induce them to select variance-increasing corporate investments, but such a risk-taking incentive of managers may decrease the value of their human capital by reducing the certainty equivalent of the stream of their employment income. Thus, managers’ incentive with respect to the level of a firm’s risk has remained an empirical issue. We extend Agrawal and Mandelker (1987) to investigate whether savings banks’ risk increases or decreases with the level of controlling shareholders’ ownership. We find that the risk of savings banks increases with higher ownership of controlling shareholders in various dimensions. First, z-score, the level of risk-aversion of a bank, decreases with the higher ownership of controlling shareholders. Second, debt-to-asset ratio, decreases with the higher ownership of controlling shareholders. Third, the PF-loan ratio, measured by project finance related loan amounts divided by total assets, increases with the higher ownership of controlling shareholders. Fourth, the variance of ROA and the variances of the cost of capital of both the equity and the debt increases with the higher ownership of controlling shareholders. In summary, the risk-taking behaviors of savings banks are strengthened with controlling shareholders’ ownership. These findings have a policy implication that government authorities should more intensively monitor the savings banks with the higher ownership of controlling shareholders.

한 쌍의 푸쉬-풀 와이어를 이용한 로봇 안구의 팬-틸트 모션 생성

정찬열(Jung, Chan-Yul),오경균(Oh, Kyung-Geune),박신석(Park, Shin-Suk),김승종(Kim, Seung-Jong) 한국소음진동공학회 2011 한국소음진동공학회 논문집 Vol.21 No.1

This paper introduces a robot eye module, of which two degree-of-freedom motions, i.e. panning and tilting, are driven by a pair of wires. The main feature of the module is that each wire can generate push-pull motion without buckling. It is thanks to a Teflon tube which guides the path of the moving wire. End points of the tube and wire have pivot elements so that a smooth push-pull motion is produced even when the end point of wire is moved by eye rotation. This mechanism helps the eye module to be very compact. In this paper, the structure of the robot eye module is introduced in detail, and the required motor angles for a certain direction of eye line are investigated analytically and experimentally.