• Proceedings of the Korea Concrete Institute Conference
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• 1996.04a
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• pp.275-279
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• 1996

In this study, the effect of external restraint on the thermal stresses and thermal cracking mode in mass concrete are analysed using the two major factors affecting external restraint such as the ratio of width go height of the placed structure (L/H) and the elastic modulus of base structure (E). For this parametric study, many cases with different values of L/H and Er are analysed by the FEM program and the co-relationship of the those major factors is examined. To evaluate the effect of external restraint on the thermal behavior of placing structure, internal restraint stress caused by temperature difference is subtracted from total thermal stress. In the case of small value of L/H or Er, it shows as internally restricted mode indicating maximum tensile stress in surface at early age, and the external restraint makes the possibility of thermal cracking higher. However, in the case of the large values of L/H and Er, the crack index at center is smaller than at surface due to the effect of external restraint. Thus, the initial location of the thermal crack is shifted from the surface to the center and the resulting crack is formed at later age.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.23 no.5
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• pp.603-609
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• 1999

The effect of an external acoustic excitation on the wake structure behind a circular cylinder was experimentally investigated. The sound wave was excited in the frequency range of the shear layer instability and two sound pressure levels of 114 and 120dB were used in this study. As a result, the acoustic excitation modified the wake structure by increasing the velocity fluctuation energy without changing the vortex shedding frequency. The acoustic excitation enhanced the vortex shedding process and promoted the shear layer instability. Consequently, the acoustic excitation reduced the length of the vortex formation region and decreased the base pressure. In addition, the vortex strength of vortices was increased and the width of the wake was spread out due to the acoustic excitation. When the excitation frequency was identical to the shear layer instability frequency, the effect of the external flow control on the cylinder wake was maximized. In addition, with increasing the sound pressure level, the effect of the external acoustic excitation on the wake structure increased.

• Structural Engineering and Mechanics
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• v.56 no.6
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• pp.1021-1040
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• 2015

An effective method to calculate aerodynamic loads and aeroelastic responses of large wind turbine tower-blade coupled structures in yaw condition is proposed. By a case study on a 5 MW large wind turbine, the finite element model of the wind turbine tower-blade coupled structure is established to obtain the modal information. The harmonic superposition method and modified blade-element momentum theory are used to calculate aerodynamic loads in yaw condition, in which the wind shear, tower shadow, tower-blade modal and aerodynamic interactions, and rotational effects are fully taken into account. The mode superposition method is used to calculate kinetic equation of wind turbine tower-blade coupled structure in time domain. The induced velocity and dynamic loads are updated through iterative loop, and the aeroelastic responses of large wind turbine tower-blade coupled system are then obtained. For completeness, the yaw effect and aeroelastic effect on aerodynamic loads and wind-induced responses are discussed in detail based on the calculating results.

• The Korean Journal of Health Service Management
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• v.6 no.3
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• pp.39-52
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• 2012

Main purpose of this study is to provide some managerial suggestions for local small and medium-sized hospitals that are in poorer business environment than large hospitals such as university hospitals, in managing the manpower efficiently, improving business performance and enhancing competitiveness, by empirically investigating the relationship among competency, organizational structure and business performance. Major results are as follows: First, regression analysis for the effects of hospital competency on nonfinancial performance revealed that marketing competency, intangible resource competency and financial resource competency, in that order of importance, had significant influence on nonfinancial performance. Second, regarding the analysis of the effects of hospital competency on financial performance, financial resource competency, marketing competency and intangible resource competency, in that order of importance, significantly affected financial performance. Third, as for the moderating effect, significant result was obtained in an interaction between hospital competency and organizational structure. Financial resource competency had a positive significant impact on nonfinancial performance. However, it had negative significant impact on it by interactive effect with organizational structure.

• The Journal of Asian Finance, Economics and Business
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• v.7 no.12
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• pp.293-308
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• 2020

This study aims to investigate the direct relationship between ownership structure, earnings manipulation, and organizational performance, and then examine the mediating effect of earnings manipulation in the relationship between ownership structure and organizational performance. This study collected and analyzed secondary data published in financial reports related to all insurance organizations listed in the Jordanian market during the study period (from 2009 until 2018). A panel data analysis was conducted, giving a total of 200 observations. The findings of this study concluded that ownership concentration, foreign ownership, and organization size affect organizational performance proxied by ROA, ROE, and EPS, more specifically, ownership concentration and organization size have a positive effect, whereas foreign ownership has a negative effect. At the same time, board of director ownership, organizational ownership, and CEO compensation did not affect organizational performance. Next, the board of director ownership, ownership concentration, foreign ownership, and CEO compensation affect earnings manipulation separately. In addition, earnings manipulation positively affects organizational performance proxied by ROA, ROE and EPS. This means that the higher the earnings manipulation is, the higher the organizational performance is. Finally, earnings manipulation mediates the relationship between ownership concentration and foreign ownership of ownership structure, and organizational performance.

• The Journal of Asian Finance, Economics and Business
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• v.7 no.9
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• pp.329-340
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• 2020

This study investigates the effect of capital structure on the financial performance of pharmaceutical enterprises which are listing on Vietnam's stock market. The study builds the regression using ROE as dependent variable and four independent variables, including self-financing, financial leverage, long-term asset and debt to assets ratios. In addition, we use other variables as controlling ones, such as firm size, fixed asset rate and growth. We collect data for the period from 2015 to 2019 of all 30 pharmaceutical enterprises which are currently listing on Vietnam's stock market. The least square regression (OLS) is used to test the effect of capital structure to the firms' financial performance. The analysis results show that the financial leverage ratio (LR), long-term asset ratio (LAR) and debt-to-assets ratio (DR) have positive relationship with firm performance, meanwhile the self-financing (E/C) affects negatively to the return on equity (ROE). Upon the findings we suggest that the Vietnamese government should focus on stabilizing macro environment to create favorable environment for enterprises. And the pharmaceutical enterprises should build more reasonable capital structure with higher debt proportion than equity, diversifying loan mobilization channels such as issuing long-term bonds. Additionally, the firms should expand the scale appropriately to maintain development and ability to pay debts.

• 한국연소학회:학술대회논문집
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• 2003.12a
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• pp.75-81
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• 2003

In this paper, the study of effects of flow variables on flame structure and NOx emission concentration was performed in co-axial laminar partially premixed methane/air flames. the objectives are to reveal its effect as parameters were varied and to understand the correlation between flame structure and NOx emission characteristics in the reaction zone. equivalence ratio(${\Phi}$), fuel split degree(${\sigma}$), and mixing distance(x/D) were defined as a premixing degree and varied within $1.36{\sim}3.17$(equivalence ratio), $50{\sim}100$(fuel split degree), and $5{\sim}20$(mixing distance). the image of $OH{\ast}$ and $CH{\ast}$, and NOx concentration were obtained with an ICCD camera and a NOx analyzer. additionally the maximum intensity location of $OH{\ast}$ chemiluminescence and $CH{\ast}$ chemiluminescence were measured to compare each flame structures. In conclusion flame structure and NOx emission characteristics were changed from diffused to premixed flame when mixing degree was on the increase. the main effect on flame structure and NOx production was at first equivalence ratio(${\Phi}$), and next fuel split degree(${\sigma}$), and finally mixing distance(x/D).

• Proceedings of the Korean Geotechical Society Conference
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• 2010.09a
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• pp.201-204
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• 2010

Earthquake load to design a structure has been calculated from a fixed base SDOF model using amplified surface accelerations along soft soil layers. But the method dose not consider a soil-structure interaction. Centrifugal experiments that were consisted of soil, a shallow foundation and a structure were performed to find the effects of soil-structure interaction. The experiments showed that mass and stiffness of the foundation affected a response of the structure and nonlinear behavior of soil near the foundation. And a rocking displacement caused by overturning moment affected the response and increases a damping effect. In this study, the centrifugal experiment was simulated as a two dimensional finite element model. The finite element model was used for nonlinear time domain analysis of the OpenSees program. The numerical model accurately evaluated the behaviors of soil and the foundation, but the rocking effect and the behavior of structure were not described.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.05a
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• pp.153-156
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• 2003

Many researchers have tried to develop the piezoelectric shell element and verified them with the benchmarking problem of the piezoelectric bimorph beam since there is no experimental result for the control of shell structure with piezoelectric sensor/actuator. In this paper, the experiments are designed and performed to verify the control Performance of piezoelectric sensor/actuator on the shell structure. PVDF is easy to be attached on the surface of a shell structure but makes weak control forces. On the contrary, PZT makes control forces large enough to control the structure, but it is not easy to make a PZT element with curvature. To use PVDF as an actuator, the structure should be designed as flexible as possible and the voltage amplifier could make high control voltage. PVDF actuator powered by a voltage amplifier that generates output voltage from -200 to +200 volts, shows little control performance to control the vibration of an arch type shell structure. The performance of sensor looks good and the negative velocity feedback control works perfectly. The actuator voltage seems to be too small to verify the control effect Quantitatively. An experiment with high voltage amplifier is scheduled to verify the control effect Quantitatively.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.33 no.4
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• pp.158-164
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• 2023

The meaning of the diamond crystal structure and the formative beauty of the crystal form were designed from a new perspective and expressed in jewelry. In this study, we examined the literature on the crystal structure of diamonds and analyzed cases of jewelry design based on the formative characteristics of diamond crystal structure. we newly interpreted the meaning and value of diamond crystal structure, and studied the figurative design that can show the aesthetic effect of the crystal structure by designing the diamond crystal structure as jewelry. By presenting jewelry designs that take advantage of the symmetry effect of the diamond crystal structure and the repetition of the sculptural beauty, we hope that the fundamental beauty and cultural meaning of gemstones will be re-recognized.