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Park, Seyoung,Jae, Jungho,Farooq, Abid,Kwon, Eilhann E.,Park, Eun Duck,Ha, Jeong-Myeong,Jung, Sang-Chul,Park, Young-Kwon Elsevier 2019 APPLIED ENERGY Vol.255 No.-
<P><B>Abstract</B></P> <P>In the pyrolysis of lignin, lignin tends to agglomerate during the feeding stage, and the char produced can expand easily to form foam that prevents continuous operation. To solve this problem, a new bench-scale rotary kiln reactor with alumina balls was used for the pyrolysis of organosolv lignin. Also, a bench-scale fixed-bed reactor was used as a reference reactor to gain an insight on the pyrolysis phenomena from rotary kiln reactor. Compared to the fixed bed reactor, the rotary kiln reactor resulted in a higher yield of organic phase oil with high selectivity to monomeric phenolic compounds. Moreover, a larger amount of CO<SUB>2</SUB> was obtained from the rotary kiln reactor, which strongly suggests that decarboxylation is main deoxygenation path. Furthermore, a char without agglomeration and foaming inside the reactor was generated from the rotary kiln reactor. The catalytic properties of the chars produced from both reactors with nickel impregnation were tested for the gasification of high-density polyethylene to produce H<SUB>2</SUB>. Among the four different catalysts (Ni/Rotary Kiln char, Ni/Fixed Bed char, Ni/Al<SUB>2</SUB>O<SUB>3</SUB>, Ni/Activated carbon) tested, the Ni/Fixed Bed char exhibited the highest yield of H<SUB>2</SUB> (~two times higher H<SUB>2</SUB> generation) from the gasification process of high-density polyethylene. X-ray photoelectron spectroscopy and scanning electron microscopy offers that the high dispersion/distribution of Ni occurred when the fixed bed char was used as a support. All experimental findings from this study significantly suggest that Ni supported on char could be an economically viable catalyst for producing H<SUB>2</SUB> from gasification of high-density polyethylene.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Rotary kiln reactor with alumina ball was used for pyrolysis of organosolv lignin. </LI> <LI> Char agglomeration/foaming did not occur during continuous pyrolysis. </LI> <LI> Rotary kiln reactor produced higher yield of organic phase oil. </LI> <LI> Ni loaded biochar is a promising catalyst for gasification of plastics. </LI> <LI> Ni/Fixed bed char showed the highest H<SUB>2</SUB> generation for HDPE gasification. </LI> </UL> </P>
Liquidity constraints and optimal annuitization
( Seyoung Park ) 한국파생상품학회 2022 선물연구 Vol.30 No.2
In this paper, we view an individual’s annuitization decision as an American style call option whose underlying asset is financial wealth, which controls the distance to annuitization. We then derive a certain threshold of wealth over which the individual is optimal to annuitize all of her wealth. Weparticularly focus on the effects of liquidity constraints on the individual’s optimal annuitization decision, concerning their effects on the optimal investment and consumption strategies. We show that the annuitization decision can be significantly affected by the extent to which individual borrowing is constrained. More specifically, the optimal decision is for the individual to annuitize earlier with the tighter liquidity constrains she is exposed to than initially planned. This is particularly relevant to today’s pandemic situation especially with the growing concern about cutting credit limits.
Female non-smokers’ environmental tobacco smoking exposure by public transportation mode
Seyoung Kim,Jin-Soo Park,Minkyu Park,Yeji Kim,Sinye Lim,Hye-Eun Lee 대한직업환경의학회 2018 대한직업환경의학회지 Vol.30 No.-
Background: This study aimed to analyze environmental tobacco smoking exposure in female nonsmokers by public transportation mode using representative data of Koreans. Methods: Data from the Second Korean National Environmental Health Survey (2012-2014) were analyzed. Urine cotinine was analyzed by public transport behavior, secondhand smoke exposure, socioeconomic factors, and health-related factors. Participants were 1322 adult females; those with the top 75% urine cotinine concentrations were assigned to the high exposure group. A logistic regression analysis was performed considering appropriate weights and stratification according to the sample design of the Second Korean National Environmental Health Survey. Results: The geometric mean of urine cotinine concentrations differed according to public transportation modes: subway (1.66 μg/g creatinine) bus (1.77 μg/g creatinine), and taxi (1.94 μg/g creatinine). The odds ratio [OR] was calculated for the high exposure group. The OR of the taxi (2.39; 95% confidence interval, 1.00-5.69) was statistically significantly higher than the subway value (reference), and marginally significant after adjusted with life style, sociodemographic factors and involuntary smoking frequency (2.42, 95% confidence interval, 0.97-6.04). Conclusions: The odds ratio of passengers who mainly used taxis was marginally significantly higher than those of passengers who used subways and buses after adjusted with life style and sociodemographic factors. Implementation of supplementary measures and further studies on exposure to environmental tobacco smoking in taxis are warranted.
Seyoung Park,Ki-Sang Song,Abdul Md Mokter Hossain,Aboubacaar Jallow,Aristarick Lekule,Mohammed Kamara,Ramvinay Singh,Salma Begum APEC국제교육협력원 2014 Asia-Pacific Cybereducation Journal Vol.10 No.2
Regional education experts from various developing countries (Bangladesh, Nepal, Sierra Leone, Tanzania, The Gambia) of west Africa and Asia-Pacific regions and experts in ICT in education from Korea cooperated to analyze the current situation of ICT utilization for schools in developing countries. From their research and reflections of participants' countries situation following things are recommended to be considered with priorities. Firstly, the expected problems and difficulties of introducing ICT in developing country schools from six levels including (teachers level, schools level and communities level). Then, solutions thereto are derived for the following six aspects: motivation of teachers, awareness building, Funds, ICT training for teachers, ICT equipment for the teachers, transparency and accountability.
Stock Returns and Market Making with Inventory
Seyoung Park,Bong-Gyu Jang 한국경영과학회 2012 Management Science and Financial Engineering Vol.18 No.2
We study optimal trading strategy of a market maker with stock inventory. Following Avellaneda and Stoikov (2008), we assume the stock price follows a normal distribution. However, we take a constant expected rate of the stock return and assume that the stock volatility is an inverse function of the stock price level. We show that the optimal bid-ask spread of the market maker is wider for a higher expected rate of stock returns.
Park, Jaehyun,Jeon, Byongtae,Kang, Sungki,Oh, Mirae,Kim, Myonghwa,Jang, Seyoung,Park, Pyojam,Kim, Sangwoo,Moon, Sangho Asian Australasian Association of Animal Productio 2015 Animal Bioscience Vol.28 No.9
This study was conducted to investigate changes in blood enzyme parameters and to evaluate the relationship between insulin-like growth factor-1 (IGF-1), antler growth and body weight during the antler growth of sika deer (Cervus nippon). Serum enzyme activity and IGF-1 concentrations were measured in blood samples collected from the jugular and femoral veins at regular intervals during the antler growth period. Blood samples were taken in the morning from fasted stags (n = 12) which were healthy and showed no clinical signs of disease. Alfalfa was available ad libitum and concentrates were given at 1% of body weight to all stags. The experimental diet was provided at 9 am with water available at all times. There were no significant differences in alkaline phosphatase, aspartate aminotransferase, and alanine aminotransferase during antler growth, but alkaline phosphatase concentrations increased with antler growth progression, and the highest alkaline phosphatase concentration was obtained 55 days after antler casting. Serum IGF-1 concentrations measured from blood samples taken from the jugular vein during antler growth, determined that levels of IGF-1 was associated with body weight and antler growth patterns. Serum IGF-1 concentrations were higher at the antler cutting date than other sampling dates. Antler length increased significantly during antler growth (p<0.001), and there was a similar trend to between right and left beams. Body weight increased with antler growth but was not significant. Consequently it appeared that serum alkaline phosphatase concentration was related to antler growth and both antler growth and body weight were associated positively with IGF-1 concentrations during antler growth.
Improving the effectiveness of 3D Animations by visual cueing
Seyoung Park,Dong-Hee Shin 한국HCI학회 2016 한국HCI학회 학술대회 Vol.2016 No.1
Applying 3D virtual environment to educational field has great possibilities. Especially, 3D instructions could be very helpful when learning procedural-manipulative tasks with high-risk of accidents (e.g., brain surgery). To find the most effective way to present information in 3D virtual environment, this study examined the effect of visual cueing in 3D instructional animation, from the perspective of cognitive load theory. In this study, a between subjects experiment was conducted. The results showed that the two different types of visual cueing (both anticipatory and trajectory) have marginally significant effect on learning performance (accuracy score). Finally, this study suggested some design strategies to improve the effectiveness of 3D instructional animations.