• Proceedings of the SAREK Conference
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• 2005.11a
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• pp.463-468
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• 2005

An experimental study on the optimal control algorithm for central heating system for minimizing energy consumption while maintaining the comfort of indoor thermal en vironment in terms of the environmental variables such as loads and weather. experimental study has been done by one using the prototype of central heating system. As a result the optimal control algorithm shows good energy performance in comparison with conventional control one.

• Journal of Agricultural Extension & Community Development
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• v.11 no.1
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• pp.191-207
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• 2004

This study was focused on the development of greenhouse management and environmental control system using internet. The essence of this system were remote automatic control unit connected with greenhouse environmental control according to the growth stages of crops, The specific objectives of the study were; 1) to analyze need of greenhouse environmental remote control system, 2) to investigate the important functions related to greenhouse management program, 3) to explore the possibility of diffusing the system using internet.The study was carried out through review of related literature and need assessment from the research and extension workers in charge of greenhouse management using questionnaire survey, interview and field study. The results of the study were summarized as fallows: 1) About 89% of respondents responded positively on the need to establish automatic control system using internet. 2) The greenhouse management and environmental control system using internet was possible to control the greenhouse in remote, automatic, and simultaneous manner, and additionally by cellular phone in emergent situation. 3) The system was possible to precisely control the greenhouse environment, and it was able to connect the environmental control data with information on growth of crops. 4) By networking the farmer, extension educator of agricultural technology center and researcher, web based farm consulting was possible through the system. Based on the results of the study recommendations were suggested as follows: 1) Thorough spot inspections and field trials should be performed before the diffusion of this system. 2) The costs of the system installation and maintenance should be moderate. 3) The operation of the system should be simple and easy for tamers to adopt. 4) National support should be made to build better internet infrastructure in rural areas.

• Human Ecology Research
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• v.59 no.3
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• pp.325-340
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• 2021

The purpose of this study was to examine that multiple mediating effects of self-determination and self-efficacy in the relationship between the parental control and career maturity. In the study, 747 university students in Daegu, Busan and Seoul area were surveyed on their perceived level of parental control, career maturity, self-determination and self-efficacy. Data were analyzed using descriptive statistics, one-way ANOVA, and Pearson correlation analysis with SPSS 25.0 program, Hayes'Process Macro program and bootstrapping. The major results of this study were as follows; First, there were significant differences in college student's career maturity by grade, major, experience in career-related services and part-time job experience period. Second, there were significant correlations between parental control(behavioral control and psychological control), career maturity, self-determination and self-efficacy. Third, self-determination and Self-efficacy had multiple mediating effects in the relationship between parental control and career maturity. In conclusion, this study found multiple mediating effects of self-determination and self-efficacy in the relationship between parental control(behavioral control and psychological control) and career maturity. It was also found that parental behavioral control had a positive effect on career maturity by increasing self-determination and self-efficacy while parental psychological control had a negative effect on career maturity by decreasing self-determination and self-efficacy.

• Journal of muscle and joint health
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• v.30 no.2
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• pp.120-128
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• 2023

Purpose: The purpose of the study was to investigate the effects of infection control knowledge and nursing work environment on infection control performance among general hospital nurses. Methods: A total of 138 nurses from four general hospitals located in G and P cities participated in this descriptive study. The collected data were analyzed using t-test, ANOVA, Pearson's correlation coefficients, and multiple regression. Results: The average mean score was 21.41±1.92 points out of 25 for infection control knowledge, 2.53±0.33 points out of 4 for nursing work environment, and 4.62±0.40 points out of 5 for infection control performance. In the final analysis, the variables that had the greatest influence on infection control performance were the nursing work environment (β=.32, p<.001), working department (β=.19, p=.014), and knowledge (β=.19, p=.016). Conclusion: This study showed that nurses with a better nursing work environment, employment in general department, and more infection control knowledge delivered superior infection control performance. Therefore, to improve infection control performance, it is necessary to enhance the nursing environment and develop practical education programs for augmenting infection control knowledge.

• Journal of Korean society of Dental Hygiene
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• v.23 no.1
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• pp.1-11
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• 2023

Objectives: This study analyzed a total of 30 domestic research trends related to dental infection control from 2013 to 2022. Methods: Two researchers analyzed the research question, "What are the research trends on infection control in dental hygiene at dental clinics and dental hygiene education institutions?" The selected literature was classified according to the research subject and the purpose of the study. Results: The study sample comprised 63% dental hygienists, 30% dental hygiene students, and 7% dental workers. The research topics on dental infection control were classified into knowledge, awareness, practice, infection control education, clinic environment, and infection control personnel. The largest proportion of research on dental infection control were about awareness and practice of infection control (69%). Clinic environment, knowledge, infection control education, and infection control personnel appeared in order. Conclusions: It is believed that this can be used as a reference material to present the direction of research design for researchers studying in infection control in the field of dental hygiene in the future.

• Journal of Korean Society for Quality Management
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• v.49 no.4
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• pp.467-482
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• 2021

Purpose: The main theme of this study is to determine the optimal control limit of conditional variance investigation by mathematical approach. According to the determination approach of control limit presented in this study, it is possible with only one parameter to calculate the control limit necessary for budgeting control system or standard costing system, in which the limit could not be set in advance, that's why it has the advantage of high practical application. Methods: This study followed the analytical methodology in terms of the decision model of information economics, Bayesian probability theory and Taguchi's quality loss function concept. Results: The function suggested by this study is as follows; ${\delta}{\leq}\frac{3}{2}(k+1)+\frac{2}{\frac{3}{2}(k+1)+\sqrt{\{\frac{3}{2}(k+1)\}^2}+4$ Conclusion: The results of this study will be able to contribute not only in practice of variance investigation requiring in the standard costing and budgeting system, but also in all fields dealing with variance investigation differences, for example, intangible services quality control that are difficult to specify tolerances (control limit) unlike tangible product, and internal information system audits where materiality standards cannot be specified unlike external accounting audits.

• The Journal of Industrial Distribution & Business
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• v.10 no.12
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• pp.35-42
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• 2019

Purpose : This study examines The impact of human resource investment in internal control on stock price crash risk. Effective internal control ensures that information provided is complete and accurate, financial statements are reliable. By overseeing management, internal control systems can reduce agency costs between management and outside parties. In Korea, firms have to disclose information about internal control systems. The working experience of human resources in internal control systems is also provided for interested parties. If a firm hires more experienced internal control personnel, it can better facilitate the disclosure of information. Prior studies reported that information asymmetry between managers and investors increases future stock price crash risk. Therefore, the longer working experience internal control personnel have, the lower probability stock crashes have. Research design, data and methodology : This study analyzed the association between the working experience of internal control personnel and crash risk using regression analysis on KOSPI listed companies for fiscal years 2016 through 2017. The sample consists of 1,034 firm-years of non-financial firms whose fiscal year end on December 31. Career spanning data of internal control personnel was collected from internal control reports. The professionalism(IC_EXP) was measured as the logarithm of the average working experience of internal control personnel in months. Negative conditional skewness(NSKEW) and down-to-up volatility (DUVOL) are used to measure firm-specific crash risk. Both measures are based on firm-specific weekly returns derived from the expanded market model. Results : We find that work experience in internal control environment is negatively related to stock price crashes. Specifically, skewness(NSKEW) and volatility (DUVOL) are reduced when firms have longer tenure of human resources in internal control division. The results imply that firms with experienced internal control personnel are less likely to experience stock price crashes. Conclusions : Stock price crashes occur when investors realize that stock prices have been inflated due to information asymmetry. There is a learning effect when internal control processes are done repetitively. Thus, firms with more experienced internal control personnel could manage their internal control more effectively. The results of this study suggest that firms could decrease information asymmetry by investing in human resources for their internal control system.

• 제어로봇시스템학회:학술대회논문집
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• 2004.08a
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• pp.1981-1986
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• 2004

In this study, the basic motor control system had been investigated. The controller for this study consists of two main parts, a feedforward controller part and a feedback controller part. Each part will deals with different control problems. The feedback controller deals with robustness and stability, while the feedforward controller deals with response speed. The feedforward controller, used to solve the tracking control problem, is adaptable. To make such a tracking perfect, an adaptive law based on Feedback Error Learning (FEL) is designed so that the feedforward controller becomes an inverse system of the controlled plant. The novelty of FEL method lies in its use of feedback error as a teaching signal for learning the inverse model. The theory in $H^{\infty}$-Control is selected to be applied in the feedback part to guarantee the stability and solve the robust stabilization problems. The simulation of each individual part and the integrated one are taken to clarify the study.

• Journal of the Korean Society for Precision Engineering
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• v.22 no.3 s.168
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• pp.29-37
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• 2005

In this study, the control of the free surface deformation of a magnetic fluid for the change in electromagnetic force is discussed. The free surface of magnetic fluid is formed by the balance of surface force, gravity, pressure difference, magnetic normal pressure and magnetic body force. Magnetic fluid in characteristics of fluid adjusted to the opposite direction of the gravity direction. Thus, the device of a magnetic fluid proposed the complete zero-leakage sealing, oscillator for surface control, boundary layer control, MHD, flow control, flow using magnetic levitation system and surface actuator. This study show the deformation of surface rise due to the intensity of the magnetic field and possibility of two-dimensional control of magnetic fluid through the feedback data of hall sensor.

• International Journal of Aeronautical and Space Sciences
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• v.15 no.3
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• pp.293-301
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• 2014

We present a study of vertical dynamics control of an electrostatically levitated gyro-accelerometer considering the wobbling effect and propose a tilt stabilization method with newly introduced control electrodes. Typically, a rotor in a vacuum rotates at high velocity, which may create a drift rate and lead to displacement instability due to the tilt angle of the rotor. To analyze this, first we set up a vertical dynamic equation and determined simulation results regarding displacement control. After deriving an equation for drift dynamics, we analyzed the drift rate of the rotor and the wobbling effect for displacement control quantitatively. Then, we designed new sub-electrodes for moment control that will decrease the drift amplitude of wobbling dynamics. Finally, a simulation study demonstrated that the vertical displacement control with the wobbling compensation electrodes mitigated the rotor's drift rate, showing the effectiveness of the newly proposed control electrodes.