김준식

Bio: 김준식 is an academic researcher. The author has contributed to research in topics: Adsorption & Activated carbon. The author has an hindex of 2, co-authored 7 publications receiving 11 citations.

Optimal credit policy to increase supplier's profit with price dependent demand function = 가격과 수요의 관계를 고려한 최적 신용판매정책

Abstract: Abstract This paper deals with the problem of determining an optimal length of credit period from the perspective of supplier. We assume that a retailer jointly determines the unit retail price and order size to maximize profit when he/she purchases a product for which the supplier offers a trade credit. Two widely used demand functions are adopted for the study in which demands are decreasing functions of the retail price. A procedure is presented which shows how to achieve an optimal length of credit period for suppliers. The effects of credit period on the behaviour of retailers are also investigated using an example.

Decomposition Characteristics of Residue from the Pyrolysis of Polystyrene Waste in a Fluidized-Bed Reactor

Abstract: Effective treatment of residue generated from the pyrolysis of polystyrene wastes has been one of the important factors in the recovery of styrene monomer and oil from polystyrene wastes. Depending on the experimental conditions, the yields of oil and styrene monomer are considerably decreased in the presence of residue. Here the residue was decomposed effectively in a catalytic fluidized-bed reactor. Nitrogen and silica sand were used as a fluidizing gas and a bed material, respectively. Effects of catalyst, temperature and gas velocity on the characteristics of decomposition of the residue were examined. It was found that the residue could be decomposed to oil or chemicals effectively by means of a catalytic fluidized-bed reacting system. The yields of oil and individual chemicals and the composition of the products were dependent upon the operating variables such as reaction temperature, catalyst and gas velocity.

Temperature Fluctuations and Heat Transfer in Liquid Drop Columns

Abstract: Heat transfer characteristics in a liquid drop column (0.102 m ID×1.8 m in height) have been investigated by analyzing the temperature difference fluctuations between the immersed heater and the column proper. The temperature difference fluctuations are analyzed by resorting to chaos analysis; the fluctuations have been interpreted by means of phase space portraits as well as the Kolmogorov entropy. The effects of dispersed (kerosene) and continuous (water) liquid phase velocities on the temperature difference fluctuations and heat transfer coefficients are determined. To explain the influence of immiscible liquid flow on the heat transfer coefficient, hydrodynamics and phase holdup have also been discussed. It is found that the increase in the velocities of dispersed and continuous liquid phases results in the increase of turbulence in the column, which makes the system more complicated and irregular. The injection of gas (air) or particles (6.0 mm glass bead) into the column can increase the heat transfer coefficient considerably. However, the flow behavior of the immiscible mixture is more irregular and chaotic owing to the injection of gas, whereas the system has been more uniform and periodic by adding the solid particles into the column. The heat transfer coefficient has been correlated well in terms of operating variables.