• Environmental and Resource Economics Review
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• 제22권4호
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• pp.727-757
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• 2013

This paper estimates the effects of Air Cargo companies' fuel surcharge collusion on the final airfreight prices. We show that the final prices have not been generally higher than the 'but-for prices,' and even been significantly lower for some companies. We analyze the possible reasons for such findings, and conclude that the collusion on fuel surcharges has not been successful due to the oil price hike in the cartel period. We also find that the oil price elasticities of fuel surcharges are significantly lower than 1.

• Environmental and Resource Economics Review
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• 제12권4호
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• pp.559-577
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• 2003

This paper analyzes household bottled water and water purifier expenditures, taking into account three important characteristics: expenditures may be censored at zero, may be interdependent across expenditure type, and may be endogenously and jointly determined. Censoring, interdependence, and endogeneity of the two expenditures are examined through simultaneous equation bivariate Tobit model. Expenditure function parameters are estimated using a 1997 household survey data collected in Seoul. The study detected interdependence between the two expenditures in the data. Moreover, the coefficient of one expenditure variable is statistically significant in the other expenditure equation. Thus, the overall results show that the simultaneous equation bivariate Tobit model employed here is appropriate for this analysis of the two expenditures. Finally estimated income and household size elasticities of the expenditures are presented.

• Journal of Korean Society of Transportation
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• 제23권8호
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• pp.67-75
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• 2005

This study analyzed the relationships between expenditures on transportation and those on communications, using consumer expenditure data from the U.S. for the 19 years 1984-2002. We first identified 12 categories of goods for transportation and communications, and then applied the linear approximate Almost Ideal Demand System(LA/AIDS) method for estimating consumer demand functions based on aggregating the categories to five (public transportation, personal vehicle capital, personal vehicle operation, electronic communications media, and print communications media) due to the small sample size. Expenditure and price elasticities were also calculated at mean values of expenditure shares. The results indicate that transportation and communications categories have both substitutive(e.g. public transportation and electronic communications media) and complementary(e.g. private vehicle capital and electronic communications media) relationships. Additionally, expenditures in the transportation categories are generally more income-elastic than those in communications.

• Journal of Korean Society of Transportation
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• 제23권8호
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• pp.193-202
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• 2005

Due to the importance of SCM(Supply Chain management) in business logistics. many studies related to the SCM performance measurement have been conducted. However, previous SCM performance measurement models have not reflected both ways, operational efficiency and response for market shift. The aim of this research is to suggest a dynamic model to measure SCM performance both with operational efficiency and response for market shift, based on previous SCOR model. To achieve this aim, we developed a cognitive map-based model described eleven KPIs (Key Performance Indicators) with different weight values. And, to measure response level for market shift, we used the concept of entropy-elasticities. Finally, through some actual cases, merits that have no previous models were shown.

• Journal of the Korean Wood Science and Technology
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• 제18권3호
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• pp.42-52
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• 1990

In this study, thick 24mm glulams were composed of thick. 3, 4, 6, 8mm Larch laminas to study that the theoretical analysis and the experimental analysis regarding the location of neutral axis of the glulams were compared, and to study on the effect of location of neutral axis on mechanical properties of glulam. The variation of location of neutral axis after proportional limit(or elastical limit) was studied to offer basic data to make the better composition method of glulam. The result obtained can be summarized as follows: 1. The theoretical neutral axis was 0.547 in solid wood, and also 0.547 in glulams because glulams were composed of only Larch laminas. 2. In solid wood, the deviation of the theoretical and the experimental neutral axis location was 0.1%, But in glulams, the deviation from-12.2% to + 7.8% showed nonuniform pattern but no large deviation. Because laminas was only of Larch and so the mechanical properties of laminas were monotonous. 3. The neutral axis exerted no influance on the elasticity of glulam, which meaned that the maximum shear strength in the neutral axis showed no influance on elasticity limit. 4. The only minutely lower elasticities of glulam than that of solid wood were shown. This was because of influance of glue lines of glulam on the elasticlties. 5. The failure type of glulam was wholly simple tension failure and the horizontal shear failure near neutral axis was not taken place, which was that glue line was complete in bonding and the strength of the lamina was not various but uniform. 6. The ratio of tension strain($^{\varepsilon}t$) I compression strain($^{\varepsilon}c$) initially showed uniform level After the elasticity limit. the ratio was increased with the flow of time and so the tension strain was more increased than compression strain. So this proved tension lamination technique, which is that the mechanical properties of glulam could be improved, if the lamina of more superior strength would he added on the bottom side of the glulam.

• International Journal of Concrete Structures and Materials
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• 제10권sup3호
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• pp.97-108
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• 2016

When the energy performance of concrete is substantially higher than that of normal type concrete, such concrete is regarded as energy efficient concrete (WBSCSD 2009). An experimental study was conducted to investigate mechanical properties of energy efficient concrete with binary, ternary and quaternary admixture at different curing ages. Slump test for workability and air content test were performed on fresh concretes. Compressive strength, splitting tensile strength were made on hardened concrete specimens. The mechanical properties of concrete were compared with predicted values by ACI 363R-84 Code, NZS 3101-95 Code, CSA A23.3-94 Code, CEB-FIP Model, EN 1991, EC 2-02, AIJ Code, JSCE Code, and KCI Code. The use of silica fume increased the compressive strengths, splitting tensile strengths, modulus of elasticities and Poisson's ratios. On the other hand, the compressive strength and splitting tensile strength decreased with increasing fly ash.

• Journal of Labour Economics
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• 제27권3호
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• pp.1-23
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• 2004

To investigate the interdependence of the decisions on when to retire and how much consume before and after retirement, we compare the pre- (or post-) retirement consumption conditioned on the retirement decision with pre- (or post-) retirement consumption regardless of retirement decision by using the Korea Labor and Income Panel Study(KLIPS). We employ the two-stage switching regression for the econometric method to investigate the interdependence of two decisions of retirement and pre- or post retirement consumption. Then we test the existence of the interdependence in terms of the significance of the estimated selection biases which appear in the pre- (post-) retirement consumption equations for early and late retirees. In those equations, we also compare the income elasticity of the consumption of the early retirees with that of the late retirees. The empirical results show that there is negative selection bias in early retirees' consumption. These results imply that due to the early retirement decision early retirees would have consumed less than they actually have. The income elasticities of the consumption of the early retirees is smaller than that of the late retirees in pre- (or post-) retirement consumption equation. This result shows that relatively longer retirement period due 10 the early retirement affect the pre-retirement consumption. early retirees' marginal propensity to consume should be lower than that of the late retirees.

• Environmental and Resource Economics Review
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• 제17권3호
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• pp.1-29
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• 2008

The goal of this study is to analyze the effects of the second energy tax reform of the transportation sector in Korea. For this purpose, we estimated the elasticities of energy demand(for gasoline, diesel and LPG) by using the ARDL(Auto-Regressive Distributed Lag) Model during the period of 1997 and 2005. We have the empirical results that the demand for diesel would decrease as much as of 382 million barrel per year and the demand for LPG would increase as much as of 20 million barrel per year since 2007. The second energy tax reform would also result in the decrease of 27,346 ton of air pollutants and 0.96 million ton of carbon dioxide per year. This shows that the second energy tax reform would have achieved its own policy goals by reducing energy demand and improving the quality of environment.

• Journal of Korean Society of Transportation
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• 제30권3호
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• pp.17-30
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• 2012

This study analyzes the basic characteristics needed for motivating modal shift from truck to rail. The object of the study is to consider the resistance factor for container transported inland and the object point is the transfer node where modal shift occurs. The main contents of the study are as follows. First, the study looks at what shippers, engaged in inland transport of container, think of current transfer node environment. From this, the study analyzes what resistance factors are attributable to the lack of motivation in modal shift from truck to rail. Second, the study estimates mode choice models in which the resistance factors at transfer node are applied. Also by using this, the study draws out elasticities, and analyzes characteristics of resistantance factors in modal shift. Third, as its result, the study suggests methods to promote modal-shifting container transport from truck to rail.

• Journal of Energy Engineering
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• 제5권1호
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• pp.87-92
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• 1996

This paper formulates dynamic optimization model for Time-Of-Use Rates when a electric power system consists of three generators and a rating period is divided into three sub-periods. We use Pontryagin's Maximum Principle to derive optimal price and investment policy. Particularly the cross-price elasticities of demand are considered in the objective function. We get the following results. First, the price is equal to short-run marginal cost when the capacity is sufficient. However, if the capacity constraint is active, the capacity cost is included in the price. Therefore it is equal to the long-run marginal cost. Second, The length of rating period affects allocation of capacity cost for each price. Third, the capacity investment in dynamic optimization is proportional to the demand growth rate of electricity. However the scale of investment is affected by not only its own demand growth rate but also that of other rating period.