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RBL 2H3 비만세포에서 히스타민 유리와 칼슘과의 관계
박성훈,김수정,김정민,박주현,최방실,이지윤,최미영,심상수,Park, Sung-Hun,Kim, Soo-Jeong,Kim, Jung-Min,Park, Ju-Hyun,Choi, Bang-Shil,Lee, Ji-Yun,Choi, Mi-Yeong,Sim, Sang-Soo 대한약학회 2007 약학회지 Vol.51 No.1
To investigate the relation between extracellular Ca$^{2+}$ and histamine release, we observed agonist-induced histamine release from RBL 2H3 mast cells in the presence or absence of extracellular Ca$^{2+}$ concentration. Histamine release induced by melittin and thapsigargin were greater in the presence of extracellular Ca$^{2+}$ than in the absence of extracellular Ca$^{2+}$. Econazole-induced histamine release had nothing to do with extracellular Ca$^{2+}$, whereas arachidonic acid-induced histamine release increased in the absence of extracellular Ca$^{2+}$. Calmodulin antagonists did not affect melittin-induced histamine release but they may potentiate arachidonic acid-induced histamine release. These data suggest that arachidonic acid-induced histamine release may be mediated via Ca$^{2+}$-independent pathway and may be potentiated by the block of Ca$^{2+}$-dependent pathway.
박성훈 ( Sung Hun Park ),김대철 ( Dae Cheol Kim ) 한국생산성학회 2015 生産性論集 Vol.29 No.1
The purpose of the study is to verify the presence of congestion in the operations of public hospitals in South Korea. Moreover, the differences in congestion and efficiency among the types(foundation type/treatment function) of public hospitals are analyzed. To do these, a DEA model is developed and “the 2013 National Public Hospital Guidance” that was provided by the Public Health Support Unit of National Medical Center is utilized. For the DEA model of congestion and efficiency, the following five inputs are selected: number of doctors, number of nurses, number of medical technicians, number of administrative staffs and number of sick-beds. As for the outputs for the analyses of congestion and efficiency, number of hospitalized patients, number of outpatients and medical profits are considered. The summary of the major results of the study is as follows. First, we find that there are congestions in the operations of public hospitals. For each input, public hospitals generally show a high rate of congestion occurrence as well as a large size of congestion in the operations. There are some differences in the congestion among the foundation types of public hospitals. The national hospitals are found to have a larger occurrence rate and the size of congestion than the special corporate hospitals and geriatric hospitals with respect to every input except for the number of medical technicians. As for the types of treatment function, the special medical treatment-centric (diseases) hospitals are found to have a larger size of congestion than the general medical treatment-centric hospitals and elderly-specialized hospitals in all the inputs. Second, in the case of the differences in the efficiency among the foundation types of public hospitals, the special corporate hospitals show the highest efficiency, followed by the geriatric hospitals and the national hospitals. As for the types of treatment function, the general medical treatment-centric hospitals are found to have a higher degree of efficiency than the elderly-specialized hospitals. The followings state the contributions of the study. First, in this research, the congestion of public hospitals of South Korea is measured and the existence of the congestion is verified for the first time by leveraging the congestion DEA model which would measure the special case of an inefficient situation. These results provide the practical implication that could help determine the priority of management by comparing the congestion for each input. Second, the differences in the efficiency among the types of foundation and treatment function are also analyzed. This achievement helps to establish a foundation which could enhance the understanding of the public hospitals by the environmental factors.
박성훈(Sung Hun Park),최승욱(Seung Uk Choi) 한국경영학회 2019 經營學硏究 Vol.48 No.6
The incentives of engaging in earnings management varies depending on the business environment. In this study, we explore the tendency of earnings management of rehabilitation firms based on time-series investigation. There are few studies who examine earnings management of rehabilitation firms. In particular, previous studies related to the rehabilitation process have focused on the firm performance after the completion of rehabilitation procedure. To the best of our knowledge, none of them directly examine the earnings management throughout the rehabilitation process. Therefore, this study investigates the earnings management of rehabilitation firms by using the time series method. Specifically, we divide the procedure into 5 steps which are: the year immediately preceding the start year (- 1 year), the start year, the progress year, the ending year, and the immediately following year after closing the procedure (+ 1 year). The results of this study are as follows. We first document significant negative relations between the discretionary accruals and the year -1 and the start year compare to control group. In contrast, significant and positive discretionary accruals are observed during the progress year. We also find evidence of positive earnings management at the progress year using performance matched discretionary accruals. We interpret this finding as the presence of incentive for the manager to overestimate earnings for the early termination of the rehabilitation process. Moreover, this higher discretionary accruals at the progress year incrementally decreases as the leverage ratio increases. Increasing leverage ratio may reflect the increase in creditors right to intervene the process, thereby restrict the incentive for management to manipulate reported earnings. Our findings are consistent in the results of using different samples as a control group and in the two-stage regression analysis models applied to control existing endogeneity issues in our models. Collectively, our study contributes to the literature and practice by finding significant earnings management during the rehabilitation process. However, this study has a limitation that the number of samples of rehabilitation firms is too small. We expect that the data will be accumulated through subsequent studies to overcome this limitation in the sample selection.