• Title/Summary/Keyword: Omitted Variables

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Income Inequality Decomposed by Age, Period and Cohort Effects: A Comparison of the Capital and Non-Capital Regions (연령, 시간, 코호트효과를 고려한 소득 불평등: 수도권과 비수도권 간 비교)

  • Jeong, Jun Ho
    • Journal of the Economic Geographical Society of Korea
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    • v.23 no.2
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    • pp.166-181
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    • 2020
  • This paper attempts to compare and analyze the intensity, trend, and regional gap of income inequality, capitalizing upon the Age-Period-Cohort model which considers age, time and cohort effects, with the 1998-2018 Korea Labor Panel (KLIPS) survey data for respondents living in the Capital and Non-Capital Regions. The main analysis results are as follows. First, in the case of both cohort and age effects, those in their 50~60s, including the so-called baby boomers and '386 generation' living in the Capital Region, have relatively lower income inequality effect compared to that of other age groups and cohorts in the Non-Capital Region. Second, the micro-individual characteristics cannot be ignored to account for a regional gap in income inequality, but rather the effects of structural and institutional omitted variables and the social discrimination effects of individual characteristics variables are more significant in explaining it. Overall, intra-and inter-cohort income inequalities appear to overlap.

Fundamental Studies for the Automatic Control System in the Greenhouse Using Microcomputer(II) -A Development of a Controller for an Automatic Control System- (마이크로컴퓨터에 의한 시설재배의 자동화에 관한 기초연구(II) -자동화 시스템의 종합제어기 개발-)

  • 김진현;김철수
    • Journal of Biosystems Engineering
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    • v.20 no.1
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    • pp.73-86
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    • 1995
  • The automatic control system in the greenhouse have to be developed to the direction of considering various factors the variables such as condition of the cultivation and greenhouse, the properties and types of products. Therefore, it is more important to set up variables appropriately than the problems of automatic control system itself, and the automatic control system which satisfy these problems should be simplified in the aspect of operation. In addition, even the individual automations are not perfect yet, so more studies are required for the development of comprehensive automatic system in korea. This study was carried out to automatize environment control systems for greenhouse, especially from most intensive labor requiring parts such as watering, irrigating liquefied fertilizer, spraying chemicals, mixing and ventilation system, etc. The results are summarized as follows. 1. Control type tensiometer was expected to be desirable in the automation of watering system, therefore, a new tensiometer was designed and developed through this study. 2. The chemical spraying system developed through this study was found to be excellent in the aspect of operation. 3. When pulse type water discharge meter was used in the mixing of liquefied fertilizer and chemical solution, the error of mixing were range $\pm$0.1~0.15%. 4. The water level switch of electrod type used for controlling water level was found to be affective in both control performance and operation cost. 5. The water and level control system can be omitted if each tank size are standardized in accordance with greenhouse size, therefore, the installation cost might be significantly reduced. 6. The developed general controller was excellent in hardware parts, but still remained to be improved in software parts.

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Effects of Consumers' Perception of Shopping Cost and Recreational Shopping Orientation on Catalog Shopping of Apparel (의류 제품의 통신 판매와 소비자 구매 의도 -쇼핑 비용 지각과 쾌락적 쇼핑 성향을 중심으로-)

  • 이은주;이은영
    • Journal of the Korean Society of Clothing and Textiles
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    • v.20 no.5
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    • pp.826-840
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    • 1996
  • With rapid changes in social and marketing environments, catalog retailing emerges as a new method of selling clothes in Korea. In catalog shopping, in-store and multi·store search behavior are omitted saving consumers time and effort. On the other hand, consumers may lose recreational enjoyment of shopping when they purchase clothes through catalog. In this study, consumers perception of shopping cost and recreational shopping orientation were tested as consumer characteristic intervening catalog shopping behavior. The concept of shopping cost was derived from Darian(1987)'s analysis of cost and benefit of store shopping and in-home shopping. A national sample of 700 adult women was surveyed and 477 questionnaires were returned and used for statistical analysis. Nine shopping cost perception variables were found to have significant positive relationships with the purchase intention of apparel through catalog. As a result of confirmatory factor analysis, two factors of shopping cost were found; perception of lack of shopping time and perception of store search effort. Causal modeling of LISREL analysis showed that percetion of lack of shopping time was strongly related with patronizing intention of catalog shopping. Since catalog shopping exclude enjoyment of store shopping activity, it can be logically inferred that recreational store shoppers have less chance of being catalog shoppers. However, the result of LISREL analysis showed that there were no negative relationship between recreational shopping orientation and catalog shopping intention. This suggests that consumers might experience enjoyment of shopping through catalog when properly presented.

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A continuous solution of the heat equation based on a fuzzy system

  • Moon, Byung-Soo;Hwang, In-Koo;Kwon, Kee-Choon
    • International Journal of Fuzzy Logic and Intelligent Systems
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    • v.3 no.1
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    • pp.13-17
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    • 2003
  • A continuous solution of the Dirichlet boundary value problem for the heat equation $u_t$$a2u_{xx}$ using a fuzzy system is described. We first apply the Crank-Nicolson method to obtain a discrete solution at the grid points for the heat equation. Then we find a continuous function to represent approximately the discrete values at the grid points in the form of a bicubic spline function (equation omitted) that can in turn be represented exactly by a fuzzy system. We show that the computed values at non-grid points using the bicubic spline function is much smaller than the ones obtained by linear interpolations of the values at the grid points. We also show that the fuzzy rule table in the fuzzy system representation of the bicubic spline function can be viewed as a gray scale image. Hence, the fuzzy rules provide a visual representation of the functions of two variables where the contours of different levels for the function are shown in different gray scale levels

Direct Shear Test of Retrofit Anchors Using Deformed Reinforcement and Adhesive

  • Choi, Dong-Uk;Kim, Yong-Gon
    • KCI Concrete Journal
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    • v.12 no.1
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    • pp.91-99
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    • 2000
  • A new type of retrof=t anchor bolt that uses deformed reinforcing bars and a commercial adhesive was developed and then an experimental study was carried out to determine the behavior of the anchors in direct shear. The steel-to-concl몫ete interface was tested. Plain concrete slabs with about 20-MPa compressive strength were used for 23 direct shear tests performed Test variables were anchor diameters (D16, D22. and D29) and edge effect. Three different shear tests were completed: simple shear, edge shear where anchors were pulled against the concrete core, and edge shear where anchors were pushed against the concrete cover In the simple and the edge shear tests where the anchors were pulled against the core, the theoretical dowel strength determined by (equation omitted) was achieved but with relatively large displacements. The shear resistances increased with the increasing displacements. In the edge shear test where the anchors were pushrd against the cover, the peak shear strengths signif=cantly lower than the theoretical dowel strength were determined due to cracks developed in concrete when the edge distance was 80 mm. The peak strengths were about 50% of the dowel strength for Dl6 bar. and about 25% or less of the dowel strength for D22 and D29 bars. Test results revealed that the edge shear where the anchor was pushed against the cover controled.

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A Study on the Relationship of Corporate Social Responsibility and Internal Corporate Management (기업의 사회적 책임과 내부 경영 활동 관계에 관한 연구)

  • Han, Man Yong;Kang, Su Jin;Sung, Joong Ahn;Choi, Jae Woong
    • Journal of Korea Society of Digital Industry and Information Management
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    • v.9 no.4
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    • pp.267-279
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    • 2013
  • To many, recent allegations of earnings management at Enron, coupled with similar ones at many other corporations, are a strong indication of a serious decay in business ethics. Nevertheless, the field of Corporate Social Responsibility(CSR) has grown exponentially in the last decade. This study investigates the effects of CSR on earnings management. Different to precedent works which focus on Financial Performance, this study attempts to provide empirical evidence for relevance of CSR and Discretionary Accruals(DA). The study used variables in the sustainability report, and DA for its earning management too progress empirical analysis because it is believed that the measurement of accounting transparency is highly related to the CEO's opportunistic selection of the accounting. In terms of Sustainable management activities, Employee training time(ETT) is significantly and negatively associated with Discretionary accruals(DA). And also Industrial Accidents Ratio(IAR) is significantly and negatively associated with Discretionary accruals. Consequently, empirical results suggest that Discretionary accruals associated with the company's CSR activities, such as ETT, and IAR. In this study, there are limitation of generalizations and omitted variable problem.

The Impact of Auditor-Client Traffic Convenience on Earnings Management in China

  • YIN, Hong;DU, Yanbin
    • Asian Journal of Business Environment
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    • v.11 no.4
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    • pp.5-16
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    • 2021
  • Purpose: This study aims to investigate the impact of auditor-client traffic convenience on accrual -based and real earnings management of the client firms. Research design, data and methodology: Using a sample of firms listed in Shanghai and Shenzhen Stock Exchanges over the period of 2007 to 2018, this paper empirically investigates the association between auditor-client traffic convenience and earnings management. We use three measures of auditor-client traffic convenience: railway traffic convenience, expressway traffic convenience, and air traffic convenience. The accrual-based earnings management is measured by abnormal accruals estimated by industry and year using the Modified Jones Model. Results: Findings indicate that traffic convenience is conducive to detecting and restraining positive accrual earnings management and real earnings management. After changing the measurement of independent variable and dependent variable, including potential omitted variables, the results are statistically unchanged. Further, the research shows that traffic convenience can not only improve audit quality, but also lead to higher fee premiums. Auditors didn't share with clients the cost reduction benefits caused by traffic convenience. Conclusions: Traffic convenience provides auditors with easy access to the client firms, alleviating the information asymmetry and improving corporate earnings quality. The findings have implications for regulators, audit practitioners and stakeholders.

A Study on the Application of Analytic Nodal Method to a CANDU-600 Reactor Analysis

  • C.S. Yeom;Ryu, H.;Kim, H.J.;Kim, Y.H.;Kim, Y.B.
    • Proceedings of the Korea Society for Energy Engineering kosee Conference
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    • 2000.11a
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    • pp.115-120
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    • 2000
  • The analysis of flux distribution under stead-state in large power reactors with assymetry reactivity insertions requires the use of three-dimensional diffusion calculations. For the purpose, consistently formulated modern nodal methods based on higher order interface techniques have become popular tools for flux distributions in large commercial nuclear reactors. Among the earlier developments, the nodal Green's function method obtains its nodal interface equation from the transverse-integrated integral diffusion equation using a finite-medium Green's function. In this method, the outgoing current from a node surface is formulated as a response of the incoming currents and the spatially integrated neutron source within the same node. The well-known nodal expansion method is also based on an interface partial current formulation. Nodal methods high-level interface variables, i.e., interface net current and flux, may be more computationally efficient than the nodal Green's function method because they have one fewer unknown per interface. The Analytic Nodal Method(ANM), which can be classified as an interface net current technique and, was faster in solving some standard benchmark problems than the other two methods.(omitted)

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A Modified Diffusion Model Considering Autocorrelated Disturbances: Applications on CT Scanners and FPD TVs (자기상관 오차항을 고려한 수정된 확산모형: CT-스캐너와 FPD TV에의 응용)

  • Cha, Kyoung Cheon;Kim, Sang-Hoon
    • Asia Marketing Journal
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    • v.11 no.1
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    • pp.29-38
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    • 2009
  • Estimating the Bass diffusion model often creates a time-interval bias, which leads the OLS approach to overestimate sales at early stages and underestimate sales after the peak. Further, a specification error from omitted variables might raise serial correlations among residuals when marketing actions are not incorporated into the diffusion model. Autocorrelated disturbances may yield unbiased but inefficient estimation, and therefore invalid inference results. This phenomenon warrants a modified approach to estimating the Bass diffusion model. In this paper, the authors propose a modified Bass diffusion model handling autocorrelated disturbances. To validate the new approach, authors applied the method on two different data-sets: CT Scanners in the U.S, and FPD TV sales in Korea. The results showed improved model fit and the validity of the proposed model.

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An Empirical Study on the Determinants of Ownership Structure of Listed Companies in Korea : Evidence from Panel Data (우리나라 상장기업의 소유구조 결정요인에 관한 실증적 연구 : 패널자료로부터의 근거)

  • Lee, Hae-Young;Lee, Jae-Choon
    • The Korean Journal of Financial Management
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    • v.20 no.2
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    • pp.41-72
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    • 2003
  • The purposes of this paper are to build theoretical and empirically testable model to identify determining factors of ownership structure, and to analyze this model empirically using th Korea Stock Exchange panel data, and to test the impact of opening the stock market on the determinants of ownership structure. The determining factors of ownership structure identified in this paper include debt ratio, dividend, asset characteristics, profitability, growth business risk, size, institutional investors and chaebol-non chaebol dummy variable. Empirical panel estimation test reveals that this model can explain about $9\sim11%$ of the cross sectional variance in the equity ratio of large shareholders. The reasons that this model has too explanatory power are that some variables were measured with errors, and that there were some omitted variables in tested model. The regression results on the model variables ar generally in line with predictions. But the coefficient estimates on size is never significant. And it appears that the exogenous variable which explains opening the stock market has positive effect on the determinants of ownership structure.

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