Efficiency and Productivity Impacts of Restructuring the Korean Electricity Generation

Heshmati, Almas 한국경제연구학회 2013 Korea and the World Economy Vol.14 No.1

This paper investigates the performance of various generation plants in the Korean electricity market. The objective is to compare performance before and after the 2001 separation by using data from 1995 to 2006. The efficiency and productivity of the generation units is estimated by using a stochastic frontier model as well as data envelopment analysis and Malmquist productivity index. The result suggests that generation is mainly affected by facility type, maintenance cost, real fuel cost, and other costs. The national generation plan is characterized by high efficiency of nuclear plants, base type facilities, and large size facilities. It is also found that efficiency enhancement from the separation effect is not clearly discernible when comparing periods before and after the separation. Suggestions are made for the better utilization of economies of scale to further raise the efficiency of generation companies and the electricity industry through enhancement of fuel purchasing power and reallocation of labour.

The Dynamics of Private Sector Development in Natural Resource Dependent Countries

Heshmati, Almas 연세대학교 동서문제연구원 2020 Global economic review Vol.49 No.4

This paper discusses the role of private sector development in overcoming the challenges of the resource curse. It identifies the developmental factors in the private sector in natural resource dependent countries by adapting a dynamic flexible adjustment model. Its empirical results are based on panel data from 110 natural resource producers in developed, developing, and emerging countries during the period 1990–2017. The findings show that natural resource rents can foster private sector development, and the speed of adjustment towards the target level of development is faster in oil and gas exporting countries.

Free vibration analysis of functionally graded CNT-reinforced nanocomposite beam using Eshelby-Mori-Tanaka approach

M. Heshmati,M.H. Yas 대한기계학회 2013 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.27 No.11

This work deals with the effect of agglomeration and distribution of carbon nanotube on the free vibration characteristics of a functionally graded nanocomposite beams reinforced by single-walled carbon nanotubes (SWCNTs) by employing an equivalent fiber based on the Eshelby-Mori-Tanaka approach. Different SWCNTs distributions in the thickness directions are introduced to improve fundamental natural frequency of polymer composite beam. The micromechanics models used in the study include a two parameter model of agglomeration. An embedded carbon nanotube in a polymer matrix and its surrounding inter-phase is replaced with an equivalent fiber for predicting the mechanical properties of the carbon nanotube/polymer composite. The system of equations of motion is derived by using the principle of virtual work under the assumptions of the Euler-Bernoulli beam theory. The finite element method is employed to obtain a numerical approximation of the motion equation. Numerical results are presented in both tabular and graphical forms to figure out the effects of nanotube agglomeration, CNTs distribution and boundary conditions on the dynamic characteristics of the beam. The above mentioned effects play very important role on the dynamic behavior of the beam.

A Comparison of Factors Shaping the Public Image of Nurses and Their Attributed Importance from the Perspective of Nurses and the General Public

Fatemeh Heshmati Nabavi,Ashraf Abdollahi 한국간호과학회 2015 한국간호과학회 학술대회 Vol.2015 No.10

Balancing Power: A Grounded Theory on Academic-service Partnerships in Implementing Clinical Education in Iran

Fatemeh Heshmati Nabavi,Zohreh Vanaki,Eesa Mohamadi 한국간호과학회 2015 한국간호과학회 학술대회 Vol.2015 No.10

Efficiency and Productivity Impacts of Restructuring the Korean Electricity Generation

Almas Heshmati 한국경제연구학회 2013 Korea and the World Economy Vol.14 No.1

This paper investigates the performance of various generation plants in the Korean electricity market. The objective is to compare performance before and after the 2001 separation by using data from 1995 to 2006. The efficiency and productivity of the generation units is estimated by using a stochastic frontier model as well as data envelopment analysis and Malmquist productivity index. The result suggests that generation is mainly affected by facility type, maintenance cost, real fuel cost, and other costs. The national generation plan is characterized by high efficiency of nuclear plants, base type facilities, and large size facilities. It is also found that efficiency enhancement from the separation effect is not clearly discernible when comparing periods before and after the separation. Suggestions are made for the better utilization of economies of scale to further raise the efficiency of generation companies and the electricity industry through enhancement of fuel purchasing power and reallocation of labour.

The effect of credit guarantees on SMEs' R&D investments in Korea

Almas Heshmati 기술경영경제학회 2015 ASIAN JOURNAL OF TECHNOLOGY INNOVATION Vol.23 No.3

The Korean government has invested a significant amount of resources through creditguarantee funds for promoting SMEs’ survival, performance and R&D investments. Thisstudy attempts to identify the determinants of providing credit guarantees and estimates theireffects on firms’ R&D expenditures. It takes into account the heterogeneity of variouscharacteristics of firms when looking at credit guarantees and in-house R&D investmentrelationships. This study identified factors that enhance the efficiency of funds and theireffects on firms’ R&D investment behaviours. It enables feedback effects on the publicfunds that were selected by the guaranteed firms. It proposes a number of policy measuresto promote a better balance between public and private investments to reduce risks ofbusiness failures.

An Econometric Model of Employment in Zimbabwe's Manufacturing Industries

Almas Heshmati,Mkhululi Ncube 중앙대학교 경제연구소 2004 Journal of Economic Development Vol.29 No.2

This paper is concerned with the estimation of employment relationship and employment efficiency under production risk using a panel of Zimbabwe’s manufacturing industries. A flexible labour demand function is used consisting of two parts: the traditional labour demand function and labour demand variance function. Labour demand is a function of wages, output, quasi-fixed inputs and time variables. The variance function is a function of the determinants of labour demand and a number of production and policy characteristic variables. Estimation of industry and time-varying employment efficiency is also considered. The empirical results show that the average employment efficiency is 92%.

Modeling the Dependency of Suction Stress Characteristic Curve on Void Ratio in Unsaturated Soils

A. A. Heshmati,M. R. Motahari 대한토목학회 2015 KSCE JOURNAL OF CIVIL ENGINEERING Vol.19 No.1

Geotechnical problems associated with unsaturated soils are common in semi-arid climates, where the upper soil layers arenaturally unsaturated. Once a soil becomes unsaturated, its mechanical properties become different from its saturated counterpart. The main part of effective stress in unsaturated soils resulting from the soil moisture can be defined by the Suction StressCharacteristic Curve (SSCC). Although, the suction stress characteristic curve is determined from shear strength tests, but recentworks show that the SSCC can be connected to the Soil Water Characteristic Curve (SWCC). This paper presents a simple and novelapproach to model the effect of void ratio changes on SSCC in unsaturated soils. The proposed approach can be easily utilized withexisting Soil Water Characteristic Curve (SWCC) equations to model any changes in suction stress for unsaturated soils. The mainadvantage of the suggested method is in fact its dependency to just one parameter, simply calibrated by the conventional waterretention tests. This characteristic is so applicable in hydro mechanical constitutive models of unsaturated soils. Finally, theefficiently predicting of the experimental results implicitly demonstrates the applicability of effective stress principle using theconcept of Suction Stress Characteristic Curve (SSCC) for unsaturated soils.

Effect of Stress Conditions on Collapse Deformation Behavior of a Rockfill Material

Ali Akbar Heshmati,Ahmadreza Tabibnejad,Hossein Salehzadeh,Saeed Hashemi Tabatabaei 대한토목학회 2015 KSCE JOURNAL OF CIVIL ENGINEERING Vol.19 No.6

A set of saturated and dry-saturated large-scale triaxial tests were conducted in order to explore the effects of stress conditions on the saturation-induced collapse deformation behavior of a rockfill material. Specimens were tested in different confining pressures and for dry-saturated tests the specimens were submerged in various shear stress levels. The results indicate that in all of the drysaturated tests a sudden reduction in the volume of the specimens was observed during the submerging process. The ratio of the minimum axial strength of a submerged specimen (at the end of the saturation process) to the shear strength of the specimen before saturation is defined as the coefficient of stress recovery, Csr. Results of the dry-saturated tests showed that this ratio increases as the confining pressure increases and decreases by increasing the shear stress level. According to the results of dry-saturated tests the values of internal friction angle reduction caused by saturation (Δφc), the ratio of the elasticity modulus of the material after saturation to its elasticity modulus in dry condition, i.e., Ewet/Edry, and also the saturation induced sudden volumetric strain (εvc) decrease as the confining pressure increases. However the shear stress level does not have any meaningful effect on the variation of Dfc, Ewet/Edry and (εvc).