• Asia-Pacific Journal of Business
• /
• v.9 no.1
• /
• pp.57-76
• /
• 2018

This paper studies the influence of the bilateral expansion of Korean and Chinese banks on performance. To conduct the empirical analysis, we select eleven Banks in South Korea and thirteen Banks in China over the 2000-2014 time frame. The main regression results are as followed. First, the sample bank's overseas subsidiaries have a significant effect on profitability and the profitability is somewhat deteriorates. Second, the sample bank's overseas branch and subsidiaries have a significant effect on the bank's risk. That is, the loan loss provision ratio is slightly increased but impaired loan ratio is highly decreased. Third, the sample banks' overseas branch and subsidiaries also have a significant effect on bank efficiency. The ratio of customer deposits per employee worsens somewhat but the gross loan per employee are increased. In conclusion, as time passes, bank profitability or efficiency from mutual expansion of Korean banks and Chinese banks seem to be improving somewhat, and this phenomenon is more prominent at Korean banks than at Chinese banks.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.21 no.1
• /
• pp.55-62
• /
• 2009

Relatively low cycle performance of a conventional $CO_2$ system is partly due to significant increase in friction loss in the expansion process, since the pressure drop across the expansion device is considerably large compared to a conventional refrigeration cycle. To recover friction loss and increase refrigeration effect by providing isentropic expansion, a rotary vane type expander has been designed. Performance of the designed expander has been investigated by numerical simulation. With the pressure condition of 9 MPa/4.5 MPa and inlet temperature of $35^{\circ}C$, volumetric, isentropic, and mechanical efficiencies of the expander are calculated to be 58.1%, 101.1%, and 78.8%, respectively, resulting in total expander efficiency of 46.3%. With this expander, COP of a $CO_2$ refrigeration cycle is estimated to be improved by about 14%.

• Proceedings of the KIEE Conference
• /
• 1996.07b
• /
• pp.793-796
• /
• 1996

This study proposes a new algorithm which performs a production simulation under various constraints and maintains computational efficiency. In order to consider the environmental and operational constraints, the proposed algorithm is based on optimization techniques formulated in LP form In the algorithm, "system characteristic constraints" reflect the system characteristics such as LDC shape, unit loading order and forced outage rate. By using the concept of Energy Invariance Property and two operational rules i.e. Compliance Rule for Emission Constraint, Compliance Rule for Limited Energy of Individual Unit, the number of system characteristic constraints is appreciably reduced. As a solution method of the optimization problem, the author uses Karmarkar's method which performs effectively in solving large scale LP problem. The efficiency of production simulation is meaningful when it is effectively used in power system planning. With the proposed production simulation algorithm, an optimal expansion planning model which can cope with operational constraints, environmental restriction, and various uncertainties is developed. This expansion planning model is applied to the long range planning schemes by WASP, and determines an optimal expansion scheme which considers the effect of supply interruption, load forecasting errors, multistates of unit operation, plural limited energy plants etc.

• Geomechanics and Engineering
• /
• v.24 no.2
• /
• pp.167-178
• /
• 2021

Spatial variability is an inherent uncertainty of soil properties. Current reliability analyses generally incorporate random field theory and Monte Carlo simulation (MCS) when dealing with spatial variability, in which the computational efficiency is a significant challenge. This paper proposes a KL-FORM algorithm to improve the computational efficiency. In the proposed KL-FORM, Karhunen-Loeve (KL) expansion is used for discretizing random fields, and first-order reliability method (FORM) is employed for reliability analysis. The KL expansion and FORM can be used in conjunction, through adopting independent standard normal variables in the discretization of KL expansion as the basic variables in the FORM. To illustrate the effectiveness of this KL-FORM, it is applied to a case study of a strip footing in spatially variable unsaturated soil under rainfall, in which the bearing capacity of the footing is computed by numerical simulation. This case study shows that the KL-FORM is accurate and efficient. The parametric analyses suggest that ignoring the spatial variability of the soil may lead to an underestimation of the reliability index of the footing.

• Journal of the Korean Institute of Gas
• /
• v.21 no.4
• /
• pp.42-46
• /
• 2017

As $CO_2$ emission with imprudent using fossil fuel, annual mean temperature of earth is increased in every year. Geothermal energy is inexhaustible energy resource to solve this problem. Heat pump performance and heat exchange efficiency of ground loop are important to distribute widely. Thus, this study are performed to increase heat pump performance and heat exchange efficiency of ground loop with dual expansion valves and spacer. As a results, COP of cooling & heating is obtained improvement up to 11.4% using dual expansion valves, and heat exchange efficiency is increased up to 17.5% using spacer. It will be reduced initial installation cost due to increasing heat pump performance and heat exchange efficiency of ground loop.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.16 no.1
• /
• pp.84-90
• /
• 2004

In order to evaluate the performance of carbon dioxide cycle, a simulation model was developed to predict the steady state performance of $CO_2$ transcritical cycle. The expansion process is treated as an isenthalpic throttling process or isentropic expansion process. The mathematical model is based entirely on the basic energy conservation law and thermodynamic and transport properties of $CO_2$. A Parametric study has been conducted in order to investigate the effect of isentropic efficiency of expansion turbine and various operating conditions on the cycle performance. An optimal heat rejection pressure existed for the given evaporating temperature and outlet temperature of gas cooler.

• Journal of Advanced Marine Engineering and Technology
• /
• v.24 no.6
• /
• pp.89-95
• /
• 2000

To obtain an exact flow loss in piping systems is very important in the face of efficiency anticipation and work control of plant. The object of this study is to get the flow loss through the experiment for sudden expansion and contraction part of circular pipe nozzle. The experiment in this study is performed after getting the flow loss factor for sudden expansion and contraction through preliminary experiments. It is confirmed that the results of this study agreed with the approximated equation of Ikeda and Matsuo. It is proved that flow loss factor ${\zeta}_3$for sudden expansion and contraction part of circular pipe is dependent on $L/D_1$in these experimental conditions.

• Journal of Korea Society of Industrial Information Systems
• /
• v.8 no.2
• /
• pp.45-53
• /
• 2003

The significances of this paper are of two points. One is that this research develops the query expansion search by adding the related terms based on the dictionary to the original query terms. This method shortens the process of the conventional model of query expansion utilizing the feedback data of the search. The other is that this research tries to find out the optimal point of precisions and recalls by differentiating the weight ratio between original quay and additional terms. This method shows that the efficiency and precision of query expansion search increase.

• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.20 no.4
• /
• pp.80-86
• /
• 2021

Plastics are widely used in mechanical and other fields due to their light weight, design flexibility, and molding processability. In processing plastics, defective products are mixed and reprocessed to improve production efficiency and reduce costs. In this study, an experiment was conducted to confirm the coefficient of thermal expansion of HDPE during this reprocessing. The coefficient of thermal expansion was measured at different measurement directions and heating rates. As a result, we observed that the coefficient of thermal expansion in the direction perpendicular to the injection direction is greater than that in the horizontal direction.

• Journal of Energy Engineering
• /
• v.21 no.4
• /
• pp.411-418
• /
• 2012

The effect of built-in volume ratio of expander on the performance of a two-loop Rankine cycle system for engine waste heat recovery of vehicle has been investigated. In the case of positive displacement expander in the various operating condition of the vehicle, it can operate in both under-expansion and over-expansion conditions. Therefore, the analysis of off-design performance for the expander is very important. Furthermore, the volume and weight of the expander as well as the efficiency must be considered in the optimization of the expander. This study shows that the built-in volume ratio of expander causing under-expansion at a target condition is more desirable considering the off-design performance and size of the expander, based on the simple modeling of off-design operation of the expander.