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New Bounds on Real Option Values
Unyong Pyo 한국재무학회 2007 한국재무학회 학술대회 Vol.2007 No.04
This paper constructs narrow bounds around the value of real options embedded in capital budgeting decisions by applying the minimax deviations approach to real options in incomplete markets. While it is straightforward to obtain the unique value of a real option with HARA utility functions, the parameters of risk-aversion are often subject to misspecification and raise concerns for practical uses. Recognizing that investors allow deviation from parameter values related to a benchmark pricing kernel, we derive narrow bounds on a real option price. Comparison with the approaches in the literature clarifies advantages of the minimax bounds: simple, consistent, and efficient.
( Unyong Kim ),( Sang Beom Han ),( Oh-seung Kwon ),( Hye Hyun Yoo ) 한국질량분석학회 2011 Mass spectrometry letters Vol.2 No.1
The purpose of this study is to investigate the in vitro metabolism of hesperetin, a bioflavonoid. Hesperetin was incubated with rat liver microsomes in the presence of NADPH and UDP-glucuronic acid for 30 min. The reaction mixture was analyzed by liquid chromatography-ion trap mass spectrometer and the chemical structures of hesperetin metabolites were characterzed based on their MS/MS spectra. As a result, a total of five metabolites were detected in rat liver microsomes. The metabolites were identified as a de-methylated metabolite (eriodictyol), two hesperetin glucuronides, and two eriodictyol glucuronides.
Unyong Pyo,Yong Jae Shin,Howard E. Thompson 한국재무학회 2009 한국재무학회 학술대회 Vol.2009 No.05
We show how target debt ratios can improve the investment incentives in firms with risky debt outstanding and with asymmetric information. While profitable investments in a firm with risky debt and/or asymmetric information can reduce the value of existing equity, new debt offsets the value loss to old shareholders. Since financing a part of investments with new debt set by target debt ratios offsets wealth transfer effects, firms will not pass up valuable investment opportunities and will make the optimal investment decisions. For the effectiveness of target debt ratios, the new debt can be issued with shelf registration and can maintain the same priority as in the old debt.
Resolving the Underinvestment and Asymmetric Information Problems with Target Debt Ratios
Unyong Pyo,Yong-Jae Shin,Howard E. Thompson 한국재무학회 2010 한국재무학회 학술대회 Vol.2010 No.05
We show how target debt ratios in book value terms applied to new investment can be used to improve alignment of investment incentives toward value maximization in firms with risky debt outstanding and asymmetric information. While wealth transfer from both agency conflicts can reduce the value of existing equity, new debt offsets the value loss to old shareholders. Since financing a part of investments with new debt set by book debt ratios offsets wealth transfer effects, firms will not pass up valuable investment opportunities and will make optimal investment decisions. Numerical examples show that both agency conflicts can be eliminated with new debt set by a target book debt ratio.
Unyong Pyo,Yong Jae Shin,Howard E. Thompson 한국로고스경영학회 2009 한국로고스경영학회 학술발표대회논문집 Vol.2009 No.7월
We show how target debt ratios can improve the investment incentives in firms with risky debt outstanding and with asymmetric information. While profitable investments in a firm with risky debt and/or asymmetric information can reduce the value of existing equity, new debt offsets the value loss to old shareholders. Since financing a part of investments with new debt set by target debt ratios offsets wealth transfer effects, firms will not pass up valuable investment opportunities and will make the optimal investment decisions.
Novel Approach for Comprehensive O-Glycosylation Profiling of Therapeutic Glycoproteins
Unyong Kim,Myung Jin Oh,Hyun Joo An 한국당과학회 2016 한국당과학회 학술대회 Vol.2016 No.01
Protein glycosylation with structural diversity is one of the most abundant post translational modifications. A wide range of functions for glycans has been described, from structural to regulatory roles in molecular and cellular level. Especially, sialic acid and its modifications are known to affect stability, efficacy, antigenicity, and half-life of biopharmaceuticals. Current glycosylation profiling is mainly focused on N-glycans due to availability of enzymes for their release. In contrast, there is no corresponding enzymes for O-glycan liberation. In general, O-glycans are liberated using alkaline β-elimination which conditions are highly destructive toward sialic acid and its modifications. For this reason, comprehensive O-glycosylation profiling method which preserves the sialic acid and its modifications is required to demonstrate in respect of quality, safety and efficacy of therapeutic glycoproteins. In this study, we developed a new analytical strategy for non-destructive O-glycosylation profiling of biopharmaceuticals using O-glycopeptides produced by non-specific protease. Erythropoietins (EPOs) were digested with pronase E for six hours, and then resulting glycopeptides were enriched using a solid phase extraction with porous graphitized carbon. The biopharmaceutical O-glycosylation profiling and structural characterization were conducted on nanoLC-chip/Q-TOF MS system. We successfully applied this method to analysis of batch-to-batch variation study of darbepoetin alfa, and O-glycosylation profiling of epoetin alfa and beta.
Highly Sensitive and Selective Analytical Platform for Non-human Sialic acid
Unyong Kim,Myung Jin Oh,Nari Seo,Jaekyung Ko,Hyun Joo An 한국당과학회 2018 한국당과학회 학술대회 Vol.2018 No.01
Glycosylation, which is susceptible to the biochemical environments, is one of the most important post translational modifications in eukaryotic proteins. Moreover, glycans are involved in many important biochemical events. Especially, sialic acids which are expressed as outer terminal units on all vetebrate are play fundamental roles in cell-to-cell and cell-to-microenvionment interactions. N-acetylneuraminic acid (NeuAc) and N-acetylglycolylneuraminic acid (NeuGc) are predominant sialic acids on most mammalian cells. Unlike other mammalian except chicken, human cannot biosynthesize the NeuGc due to irreversible mutation on gene CMAH encoding CMP-N-acetylneuraminic acid hydroxylase that convert CMP-NeuAc to CMP-NeuGc. When the NeuGc is metabolically incorporated into human tissue from dietary sources (especially red meat), the anti-NeuGc antibodies which leads immune response will be produced and circulated through blood. The evidence showed that the such anti-NeuGc antibodies may cause systemic inflammation and finally can promote tumor progression. Therefore, quantitation of the non-human sialic acid NeuGc in food and therapeutic glycoproteins is of high importance. Here, we introduce analytical methods for rapid and highly sensitive identification and quantitation of NeuGc in food contents containing non-human glycan epitope using LC-MS/MS.