• 한국보육지원학회지
• /
• 제13권6호
• /
• pp.163-179
• /
• 2017

Objective: The purposes of this study are to test a direct effect of mother-child interaction and to examine the mediating effect of children's smart media use on a child's sleeping hours. Methods: We analyzed the longitudinal data of 1,494 children from the $6^{th}$ panel study of Korean children collected by the Korea Institute of Child Care and Education in 2013, which examined 5-year-old children. The main analysis method was Structural Equation Modeling (SEM). Results: The study results showed that mother-child interaction had a direct effect on the child's sleeping hours. Children's smart media use also directly influenced the child's sleeping hours. In regard to mediation, the results revealed that children's smart media use mediated the relationship between mother-child interaction and child's sleeping hours. Conclusion/Implications: Bidirectional mother-child interaction and the degree of smart media use played an important role in children's sleeping hours. This study suggests policy and practical implications in order to retain children's healthy sleeping hours.

• The Journal of Asian Finance, Economics and Business
• /
• 제7권8호
• /
• pp.87-94
• /
• 2020

The paper aims to investigate the impact of presenting statements of cash flow using the direct method and the indirect method on loan decision by credit officers at Vietnamese banks. The data was collected from 150 credit officers of commercial banks in Vietnam based on the questionnaire about making loan decision when the cash flow statement is presented in different methods, namely, direct and indirect methods. This research uses T-tests to check whether using the direct or indirect method affects the accurate calculation of loan criteria, affects the loan decision by credit officers, and compare these two methods in the aspects of information provision. The research has pointed out that: 1) the direct method helps the calculation of indicators related to loans more accurately; 2) credit officers say that, while the direct method of presenting cash flow statement provides clearer information, the use of either the direct method or the indirect method does not affect the banks' loan decision. Since then, the author recommends that cash flow statements should be provided with information in a direct method to present the information needed for loan decision more accurately so as to improve the quality of cash flow statement.

• Asia pacific journal of information systems
• /
• 제10권4호
• /
• pp.101-113
• /
• 2000

This study deals with the concept of Microcomputer Playfulness(MCP), Even though MCP was introduced recently in the MIS research, the concept is expected and empirically supported to be significant in explaining information technology adoption and usage. Based on the Technology Acceptance Model(TAM), this study presented a revised model to explain individual PC use and explored the role of MCP in PC use. The results showed that MCP has a direct influence on PC use rather than a mediator between Self-efficacy and PC use, and that MCP is a better predictor of PC use than Computer Anxiety.

• 한국산업보건학회지
• /
• 제33권2호
• /
• pp.93-102
• /
• 2023

Objectives: With the evolution of direct reading sensors, it is possible to monitor several substances through telecommunication. However, there are some limitations on the use of direct reading technologies in the Occupational Safety and Health Act in South Korea, which only applies to detector tubes, noise, heat, and carbon monoxides. The number of chemicals and their amount of use have been continuously increasing in South Korea. The Ministry of Employment and Labor (MoEL) has concerns about worker's health because exposure is only covered for about 1.2% of all distributed chemicals. Using a direct reading monitor with photoionization detectors (PID-DRMs), gases and vapors chemicals can be measured. Based on the data, business owners are able to create corrective strategies, provide better working routines, and select correct respiratory equipment. PID-DRMs are less expensive and easier to handle for an owner voluntarily controlling chemicals emitted in the workplace. However, there are several limitations on using these PID-DRMs to the degree that the MoEL has not been able to select a legal monitor. The aim of this study was to review previous studies related to PID-DRMs and identify the characterization and limitation on PID-DRMs. Methods: To search for related studies on PID-DRMs, key words were used including direct reading monitors/instruments and/or photoionization detectors. Through that, four domestic and 15 international studies were reviewed. Results: Studies on PID-DRMs were conducted by chamber (enclosed, dynamic, walk-in) and in the field (experimental environment, actual environment). The concentration of PID-DRMs and charcoal tubes were compared for a single substance or mixture, or within the PID-DRMs. There was a high correlation between the two concentrations, but it did not meet the accuracy criteria (95% confidence interval, within 25%) of the NIOSH technical report (2012). In addition, differences in measured values occurred according to environmental factors (temperature, humidity) and high concentration, and concentration values tended to be underestimated due to contamination of the sensor. As a way to improve the accuracy of PID concentration, it was proposed to use correction factors, charcoal tube-based correction factors, or to calibrate the PID-DRMs in the same environment as the workplace. Conclusions: PID-DRMs can likely be used by business owners for the purpose of voluntarily managing the workplace environment, and it is expected that it will be possible to use them as legal equipment if a PID sensor can be upgraded and the limitations of the sensor (temperature, humidity, high concentration evaluation, sensor pollution) can be overcome in the near future.

• 대한기계학회논문집A
• /
• 제24권12호
• /
• pp.2926-2934
• /
• 2000

This study presents a direct adaptive controller which is derived by using Lyapunovs direct methods for trajectory tracking control of a pneumatic cylinder. The structure of the controller is very simple and computationally efficient because it does not use either the dynamic model or the parameter values of the pneumatic system. The bounded stability of the system is shown in the presence of the bounded unmodeled dynamics. The bounded size of tracking errors can be made arbitrarily small without giving andy influences on either input or output variables. The trajectory tracking performance and the stability of the control system is verified experimentally. The results of the experiments show that the proposed controller tracks the given trajectories, sine function and cycloidal function trajectories, more accurately than PD controller does, and it stabilizes the system and adaptive variables.

• 전력전자학회논문지
• /
• 제17권1호
• /
• pp.57-66
• /
• 2012

This paper proposes a performance improvement of grid-connected inverter system using sliding-mode based direct power control with a variable gain. The proposed control method determine variable gain of PI controller by using modeling at direct power control (DPC) applied to space vector modulation method. Also, this method use sliding-mode control to maintain excellent dynamic response of character of direct power control (DPC). The validity of the proposed algorithm are verified by simulations and experiments.

• 대한전기학회논문지:전력기술부문A
• /
• 제48권8호
• /
• pp.958-964
• /
• 1999

The distance in load parameter space to the closest saddle node bifurcation (CSNB) point provides the worst case power margin to voltage instability and the left eigenvector at CSNB identifies the most effective direction to steer the system to maximize voltage stability under contingency. This paper presents an improved direct method for computing CSNB: the order of nonlinear systems equations is reduced to about twice of the size of load flow equations in contrast to about three-times in Dobson's direct method; the initial guess for the direct method is computed efficiently and robustly by combined use of continuation power flow, a pair of multiple load flow solution with Lagrange interpolation. It is also shown that voltage stability may be enhanced significantly with shift of generations in the direction of the left eigenvector at CSNB.

• 로봇학회논문지
• /
• 제14권4호
• /
• pp.311-317
• /
• 2019

Direct teaching is an essential function for collaborative robots for easy use by non-experts. For most robots, direct teaching is implemented only in joint space because the realization of Cartesian space direct teaching, in which the orientation of the end-effector is fixed while teaching, requires a measurement of the end-effector force. Thus, it is limited to the robots that are equipped with an expensive force/torque sensor. This study presents a Cartesian space direct teaching method for torque-controlled collaborative robots without either a force/torque sensor or joint torque sensors. The force exerted to the end-effector is obtained from the external torque which is estimated by the disturbance observer-based approach with the friction model. The friction model and the estimated end-effector force were experimentally verified using the robot equipped with joint torque sensors in order to compare the proposed sensorless approach with the method using torque sensors.

• 아태비즈니스연구
• /
• 제10권4호
• /
• pp.153-165
• /
• 2019

This paper examined economic liberalization and corruption in ASEAN member affect Korea's foreign direct investment. We use 160 (country-year) observations from ASEAN 10 member countries for a period of 16 years from 2001 to 2016, with the Economic Liberalization Index provided by the Fraser Institute and the corruption recognition index provided by the International Transparency Organization. As results, economic liberalization showed a non-linear(U shaped) effect on foreign direct investment and corruption has a negative effect on foreign direct investment.

• Asian Pacific Journal of Cancer Prevention
• /
• 제13권1호
• /
• pp.403-406
• /
• 2012

Mobile phones work by transmitting and receiving radio frequency microwave radiation. The radio frequency (RF) emitted by mobile phones is stronger than FM radio signal which are known to cause cancer. Though research and evidence available on the risk of cancer by mobile phones does not provide a clear and direct support that mobile phones cause cancers. Evidence does not also support an association between exposure to radio frequency and microwave radiation from mobile phones and direct effects on health. It is however clear that lack of available evidence of cancer as regards the use of mobile phone should not be interpreted as proof of absence of cancer risk, so that excessive use of mobile phones should be taken very seriously and with caution to prevent cancer.