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- 저자 : 鄭炳昱 (검색결과 321 건)
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정병욱,신창호,김영진,장상희,신부영 영남대학교 공업기술연구소 1999 工業技術硏究所論文集 Vol.27 No.1
Aerobic composting apparatus was set up using International Organization for Standardization(ISO) and ultimate biodegradability of plastic films was evaluated by measurement of released carbon dioxide at the end of test. Test materials were polycaprolactone(PCL), PCL/starch composite with various composition, photo-degradable, bio-destructible film, and high density polyethylene(HDPE) film. After 45 days, PCL and PCL/starch(70/30) composite films were degraded to 37% and 60%, respectively. This fact revealed that starch in PCL elevated the biodegradability of matrix PCL. Although photo-degradable and bio-destructible films also evolved carbon dioxide, matrix polymer(HDPE) was not degraded by microorganisms in compost. This fact was indirectly supported thermogravimetric analysis and morphology of film before and after composting.
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정병욱,박덕규 한국물리학회 2003 New Physics: Sae Mulli Vol.46 No.6
영구자석(Nd\(_2\)Fe\(_{14}\)B)을 사용한 MHD 추진(Magnetohydrodynamic propulsion) 장치의 모델을 개발\(\cdot\)제작하여 전류와 염화나트륨 수용액의 농도변화에 따른 MHD 추진력을 조사하였다. MHD 추진력을 조사하기 위하여 다양한 조건변화로 추진용 duct 내의 극판의 크기, 극판 사이의 거리, duct 양쪽의 자기장의 세기를 측정하여 최적의 MHD 추진장치인 소형 모형 선박의 구조를 결정하였다. 염화나트륨 수용액의 농도 및 극판 사이의 전류의 세기를 변화시키면서 모형선박의 이동거리와 시간을 측정하여 공급전압과 전류와의 관계, 추진력에 대한 이론값과 실험값의 비교, 평균속력도 조사하였다. 그 결과 전류세기 변화에 따라 MHD 추진력이 선형적으로 비례하여 변화하고, 염화나트륨 수용액 농도(농도변화 범위 3.5 \% $\sim$ 25 \%)가 증가함에 따라서 MHD 추진력은 차츰 감소하는 경향을 확인하였다. In this study, we made a small-scale magnetohydrodynamic (MHD) thruster to investigate the characteristics of MHD propulsion in sodium chloride solution. This thruster was made with a rare--earth permanent magnet Nd$_2$Fe$_{14}$B and platinum (Pt) electrodes in a sodium chloride solution filled with dust. In order to investigate how the critical factors, $i.e$., the size of the electrodes, the distance between electrodes, the magnetic fields of the rare-earth permanent magnet, the NaCl concentration, and the electric current, affect the MHD propulsive force in the duct, we carried out extensive experiments for various values for each factor. Using those results, we designed a MHD thruster and estimated the MHD propulsive force by using a magnetic field of 4100 Gauss supplied by a rare-earth permanent magnet Nd$_2$ Fe$_{14}$ B and an electric field of 5200 V/m supplied by a DC power supply through the platinum(Pt) electrodes NaCl concentrations ranging from 10% to 25\% and electric currents ranging from 1 A to 9 A in the duct. The strongest MHD propulsive force was found to be at a NaCl concentration of 25\%, an electric current of 9 A, when the mean velocity of the thruster ranged from to. Also, we discovered that the MHD propulsive force increased as the applied electric-currents increased at each NaCl concentrations, and that there was a greater difference between the experimental values and the theoretical values at high NaCl concentrations. The mean value of the propulsive force we measured was smaller than the corresponding theoretical value by about 73.1\%. The results obtained in this study can be provide useful data for a practical study of a large--scale MHD propulsive force.
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Access to Capital Markets and Adjustment of Capital Structures
정병욱,김현수 한국경영학회 2018 한국경영학회 통합학술발표논문집 Vol.2018 No.8
This paper provides the evidences of heterogeneity in capital structures based on accesses to capital sources while providing new empirical findings. Using a large data set of public and private firms in Korea, our paper analyzes how access to various types of capital markets affects target leverage ratios, the speed of adjustments to targets, and financing activeness. Consistent with prior research, we provide main findings that (i) public firms have lower target leverage ratios and adjusts faster to targets than do private firms, and (ii) firms with access to external bond markets have higher target leverage ratios and adjust faster to targets than do firms without such access, regardless of whether the firms are public or private or not. Moreover, we provide the significant findings that the accesses to public and external equity and bond markets lead firms to more active issuance or retirement of capital. On the contrary, the effects of internal capital markets (ICMs) are not straightforward across different combinations of accessibilities to capital markets. More strategic and business-group-wise of operations and financing activities seem to work. We find that the effects of ICMs are relatively prominent in the subgroup of group-affiliates constrained in accesses to both public and external equity and bond markets. These evidences imply that, since the private firms within a business group are in general under strong control by owner-management of the business group in Korea, their debt financing from both internal and external sources can easily be substituted by other forms of funding such as internal private equity and various subsidizations through intra-group transactions, which are other devices for constituting internal capital markets.
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신용평가정보가 기업의 손상차손 인식에 미치는 영향 : 신용등급의 내부통제효과
정병욱,황인덕 한국재무학회 2015 한국재무학회 학술대회 Vol.2015 No.11
비대칭정보인 경영자의 유형(type)과 행위(action)는 사업의 효율적인 운영과 종료를 결정하는 요인으로 기업가치에 영향을 미치므로 경영자를 선별(screening), 감시(monitoring)하는 메커니즘을 필요로 한다. 특히 현직을 유지하고자 하는 경영자의 참호 형성 유인에 의하여 부실한 사업의 신속한 정리가 제약될 수 있다. 본 연구는 경영자가 자신의 직위와 사적이익을 위하여 부실한 사업부문의 효율적인 정리를 지연시킬 수 있는 상황에서 신용평가정보가 손상차손의 자발적 인식을 확대시키는 기능을 수행함을 검증한다. 즉, 신용등급이 경영자가 자신의 사적이익을 위한 참호 구축 과정에서 부실한 사업의 상각을 지연시키는 행위를 통제하는 도구로서 기능함을 실증적으로 분석한다. 이는 신용평가정보가 경영자의 재량적 의사결정과 회계보고를 통제하는 도구로 기능할 수 있음을 시사한다. Type and activity of management are the main factors of effective operation and termination of business projects of a firm, leading to key determinants firm value. Since the type and activity of management are asymmetric information, a firm needs to design mechanism for screening and monitoring the management. Management entrenchment can restrain effective and timely termination of unprofitable business operations. This paper examines whether credit rating plays a role as an internal control device to facilitate expedite asset write-off while constraining management entrenchment and private benefit acquired from inefficient maintaining of unprofitable business operations. This paper shows clear evidence that credit rating controls management entrenchment for private benefits and expands voluntary asset write-off indicating effective termination of unprofitable business operations. In turn, this evidence provides implication that credit rating provides a mechanism controlling the management’s discretionary decision making and accounting reports for boosting up income number.
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