Single-Switch ZVZCS Quasi-Resonant CLL Isolated DC-DC Converter for 32" LCD TV

류성희,안정훈,조광승,이병국 대한전기학회 2015 Journal of Electrical Engineering & Technology Vol.10 No.4

In this paper, a single-switch ZVZCS quasi-resonant CLL isolated DC-DC converter for driving a low-power (less than 100 W) 32'' LED backlighting liquid crystal display television (LCD TV) is proposed. The proposed converter exhibits both forward and flyback operational characteristics. All semiconductors are activated and deactivated under the soft switching conditions during the switching transition without additional active devices. The switching frequency varies less than about 10 kHz for load variations, leading to minimizing the efficiency reduction under light load. Furthermore, the low di/dt and dv/dt by soft switching enhance the electromagnetic interference (EMI) performance above 1 MHz. A theoretical analysis is described in detail, and a 72-W prototype converter verifies the validity of the analysis.

서울시 주요 고속화도로와 주변 주거지역의 NOx 농도 분포

류성희,이광재,우성호,김경환,김종범,이승복,배귀남 한국대기환경학회 2014 한국대기환경학회 학술대회논문집 Vol.2014 No.10

Do Korean Firms have Changed their Financing Patterns and Capital Structures after the Asian Financial Crisis?

류성희,임석필 한국경영교육학회 2013 경영교육연구 Vol.28 No.3

We investigate Korean firms’ financing patterns, including debt and equity issuances and capital structure adjustment speed between 1989 and 2008. We test the most adequate capital structure theory that explains firms' actual debt ratio changing patterns for Korean firms. According to the trade-off theory, firms need to change their capital structures to maximize their values by achieving their optimal capital structures. In the pecking order theory, firms issue debt first when they need external funds. Our results show that firms have changed(or adjusted) their capital structures over a twenty year span, and they mainly use equity issuance. These results deny the pecking order theory, but support the trade-off theory. Our results, a negative association between stock return(SR) and debt ratios, indicate that high (or overvalued) stock price reduces debt ratio by either issuing overvalued stocks or increasing the magnitude of total asset. We use Frank and Goyal’s(2003) method and a dynamic partial adjustment process to test whether firms use debts for their financial needs and change their capital structures in order to close their optimal capital structures, respectively. Furthermore, we use a two-step System GMM estimator to improve the reliability of our estimated results for capital structure adjustment speeds as we use a panel data set that likely has an endogeneity problem. We also use both book and market based debt ratios as there is no clear criteria of right debt ratio for a capital structure study.

빅데이터 시대의 데이터에 대한 몰이해

류성희 대한산업공학회 2020 ie 매거진 Vol.27 No.1

Corporate Governance Structure and Debt Levels: Using Korean Firms

류성희 대한경영학회 2015 大韓經營學會誌 Vol.28 No.11

Since Asian Financial Crisis in 1997, the idea of corporate governance structure has been an important matter in Korea. Having a good governance structure can reduce agency costs and increase firm value. In this paper, we investigate the influence of corporate governance structure on firms’ debt ratios, using three different governance proxies, the portion of stocks held by the largest shareholders and their family members (PLS), the portion of an outside director over total board member (POD), and the portions of stocks held by foreigner (PFO). This paper includes capital structure adjustment behaviours as well as the relationship between debt level and governance structure, in line with three different governance structure proxies. In addition, as there is a high probability of existing endogeneity problem in our residual as using panel data, we avoid to use an OLS estimator but use estimators that require instrument variables. We find that PLS and POD do not show a clear association with debt levels, and many of the coefficients of them are not statistically significant. However, PFO shows a clear negative association with debt levels over estimators. We also find that high levels of governance proxies cause firms to adjust their debt levels faster: That is to say that, when the largest shareholders, independent directors or foreign investors have enough power to influence a firms’ debt level decision procedure, they do use this power. Particularly, we also find that high level of PLS has the strongest effect upon firms’ debt level shifts. With this result, we suggest the importance of strong managerial-ownership. Therefore, our results suggest that PFO has the clearest negative relationship with debt levels: and high level of PLS has the strongest impact on firms’ debt level adjustment decisions. Above all, our results suggest that although PLS and POD do not show us a clear association with debt levels, they all have influence on firms’ debt level decision policies in some way. Last, but not least, we likewise find that there are stronger relationships between debt level and controlled variables than the relationship between debt level and corporate governance proxies, across our models. This implies that although corporate governance is important and takes some roles when firms decide their debt levels, it is less important compared with firms’ other capital structure determinants.

The Critical Appraisal of Existing Comparison Methods: Bringing the Connected Histories into Chinese Stagnation Studies

류성희 서울대학교 사회발전연구소 2019 Journal of Asian Sociology Vol.48 No.2

This paper introduces the incorporating comparison method into Chinese stagnation studies. Comparative historical scholars of Chinese stagnation have faced methodological culs de sac because the unconditional acceptance of the comparison method has led to the tendency to overlook connected history between West and China in Chinese stagnation. The article is divided into two sections. First, by problematizing the comparison method, this article attempts to debunk long-held problems hitherto neglected in Chinese stagnation studies. I introduce three types of comparison methods that have been widely used in Chinese stagnation studies and then disclose the common drawback of the comparisonoriented approach. Second, as an alternative, I provide the incorporating comparison method to deal with the globalized connected histories in Chinese stagnation. This approach keeps the strong points of comparison methods by transforming the problems with them into advantages.

骨ㆍ關節結核 94例에 對한 임상적 觀察

柳聖熙 대한외과학회 1963 Annals of Surgical Treatment and Research(ASRT) Vol.5 No.10

Financial Policies between Chaebol and Non-chaebol Firms

류성희 한국경영교육학회 2015 경영교육연구 Vol.30 No.6

In this research, we investigate whether chaebol affiliations have a different financial policy compared with non-chaebol firms and a big-firm group(a group of firms that has the same average firm size with the chaebol-firm group, and does not belong to chaebol group), in debt level, cash-holding level, and investment decision policies. We use 123 chaebol affiliations out of 427 firms from 9 industries from the KOSPI market between 2001 and 2013. Our results indicate that 9 variables out of 10 show significant differences in terms of the directions and magnitudes of the coefficients of independent variables between chaebol and non-chaebol firms for debt level policy. According to our descriptive statistics, chaebol affiliations have a larger sized firm, lower bankruptcy probability and higher PER than non-chaebol firms. In other words, firms in the chaebol-firm group could have low fiancing costs with low bankruptcy probability and high stock prices. For the cash-holding policy, 4 variables show differences;and for investment policy, only 1 variable shows a significant difference between chaebol and non-chaebol firms. In this paper, we use regression models and the T-test to confirm the existence of differences in financial polices, mainly between chaebol and non-chaebol firms. As we use panel data, we use GMM, and system GMM estimators when using regression model analyses, because these estimators do not require the normal distribution of error term. When comparing the coefficients from two different regression estimators, by using the T-test, we find more compelling evidence that chaebol and non-chaebol firms have different financial policies than prior research. This is because, by using the T-test, we can obtain more solid evidence of whether firms’ financial policies are influenced by firms’ chaebol group membership; and by using this method, we often find inconsistent results with previous research. We believe that a lot of previous research should be revised using our method, as our T-test often disagrees with the results found by previous research that only use simple regression estimators. In this paper, we have several limitations. First, when using the sub-sample of big-firm group, there are not enough sample observations to investigate and to get more reliable results. Second, we do not include the probability of the fact that firms’ debt levels, cash levels and investment decisions could be affected by firms’ characteristics that occur different time periods. Third, in this paper, we only use data from the KOSPI market. Therefore, our research can not represent whole listed firms in Korea. From this paper, we learn that firms in our three sub-groups, chaebol, non-chaebol and big-firm groups, have different financial policies in line with their different financial characteristics. This research likewise provide the fact that how chaebol affiliated firms enjoy their chaebol group membership when they use debt and cash.

Debt Policies for Korean SMEs after the US Financial Crisis in 2007

류성희,임석필 한국경영교육학회 2018 경영교육연구 Vol.33 No.6

[Purpose] Prosperity of SMEs is a national concern in Korea. Although, easy financing is important for SMEs, it is the greatest barrier for them. We, therefore, study the financing policies for Korean SMEs. [Methodology] We try to explain Korean SMEs’ financing patterns using the trade-off and pecking order theories. The SMEs are additionally segregated into 4 different sub-groups in line with their size(total asset). In addition, considering an endogeneity problem when using panel data, we hire LSDV and GMM estimators. [Finding] First, SMEs reduce debt levels. Second, some variables, such as tangible assets, cash level and FDs, indirectly present that different financing policies(or theories) are applied when SMEs are financing between short- and long-term debt. Third, although we have not found a compelling evidence in statistical terms that SMEs adjust their debt levels toward optimal, continuous reducing of debt level during our sample period is a strong evidence of the trade-off theory. [Implication] Both trade-off and pecking order theories partially explain Korean SMEs’ financial policies but not entirely.

기업소유구조와 재벌변수가 기업의 부채비율변화에 미치는 영향 - 한국기업을 중심으로 -

류성희 한국전문경영인학회 2014 한국전문경영인학회 학술대회 발표논문집 Vol.2014 No.11