• Journal of Power Electronics
• /
• v.14 no.2
• /
• pp.392-401
• /
• 2014

A fast-transient repetitive control strategy for a three-phase shunt active power filter is presented in this study to improve dynamic performance without sacrificing steady-state accuracy. The proposed approach requires one-sixth of the fundamental period required by conventional repetitive control methods as the repetitive control time delay in the synchronous reference frames. Therefore, the proposed method allows the system to achieve a fast dynamic response, and the program occupies minimal storage space. A proportional-integral regulator is also added to the current control loop to eliminate arbitrary-order harmonics and ensure system stability under severe harmonic distortion conditions. The design process of the corrector in the fast-transient repetitive controller is also presented in detail. The LCL filter resonance problem is avoided by the appropriately designed corrector, which increases the margin of system stability and maintains the original compensation current tracking accuracy. Finally, experimental results are presented to verify the feasibility of the proposed strategy.

• Korean Journal of Optics and Photonics
• /
• v.15 no.3
• /
• pp.214-221
• /
• 2004

We theoretically and experimentally investigate the effect of apodization on the transmission characteristics of linearly chirped fiber Bragg gratings(CFBGs). Based on the UV beam scanning method along a phase mask, we fabricated several apodized CFBGs with different apodization profiles such as Gaussian, Raised-cosine, Blackman, and Hyperbolic tangent. During the UV beam scanning, the phase mask is dithered by a PZT(Piezoelectric transducer) which is precisely controlled by a computer program so that the apodization profiles can be flexibly applied to the grating. We measured the reflection spectra and group delay characteristics of CFBGs with the different apodization profiles, and compared them according to their properties such as reflectivity, sidelobes, and group delay ripple (GDR). The peak-to-peak of GDR could be suppressed to less than 20 ps.

• Convergence Security Journal
• /
• v.17 no.4
• /
• pp.31-37
• /
• 2017

This study compares the main features of the Act of National Contract with the Act of Defense Aquisition Program, which is the only one in Korea for long-term contracts. When applying the progress payments system to the defense R&D project, We can prevent disputes between parties and create a stable development environment through smooth partnerships. Smaller, direct and indirect losses can be alleviated, such as the waste of administrative power required to deal with disputes due to the payment of delayed prizes and restrictions on business activities due to the difficulty of forecasting the results of companies. In large measure, we will be able to procure a high-quality weapon system in a timely manner to support the security of the nation as well as international competitiveness through the growth of our defense industry.

• Journal of muscle and joint health
• /
• v.21 no.1
• /
• pp.65-74
• /
• 2014

Purpose: This study examined gender differences on Musculoskeletal disease (MSD) medical status, the characteristics of the approved patients in workers, and the factors affected approval. Methods: Claim data for the MSD to the Korea Worker's Compensation & Welfare Services (2011) were employed. The medical status by gender was analyzed using t-test, chi square-test and multivariate logistic regression models. Results: The number of claims for MSD has continuously increased in females but not in males since 2006. The severity measured by the care duration, surgery experience and disability grade has been substantially higher in males than in females. Age, size of company, types of occupation, work duration and the weight of materials handled daily were associated with the approval. When males were considered, the work duration, the weight of materials handled daily and parts of the body were statistically significant predictors of approval in males. In case of female, there were meaningful predictors in types of industry and parts of the body. Conclusion: These findings suggest that gender-specific risk factors of MSD should be measured and the management program for MSD should be developed.

• Journal of the Korean Society of Safety
• /
• v.20 no.1 s.69
• /
• pp.143-147
• /
• 2005

Immediate responsibilities for occupational health and safety (OHS) management reside in business proprietors and supervisors whose voluntary participation in OHS educational programs, not legal sanctions, may thus lead to safe and pleasant work environments. This study investigates how to promote the effectiveness of OHS educational programs to draw voluntary participations in such programs in Korea To this end, drawbacks of current practices in OHS education are first analyzed, and then OHS related policies in advanced countries in the area of disaster prevention such as United States and Germany, are also scrutinized. Based on the preliminary investigations, the following propositions are made to lay out the foundation for promoting effective OHS educational programs in Korea: improvement of government regulations, revitalizing job training initiatives, on-site OHS education, compensation and incentive programs for OHS education. These propositions may also facilitate the deployment of disaster prevention activities across the organization and prevent various occupational disorders (for example, musculoskeletal disorders). This study emphasizes that monolithic OHS education systems led by regulatory agencies may not be efficient to ensure healthy and safe work environments. Globally competitive OHS educational systems may be established only when they are based on the health and safety requirements specified by proprietors and workers.

• The Journal of Korea Robotics Society
• /
• v.9 no.1
• /
• pp.48-56
• /
• 2014

In robotic surgery, a surgeon checks only a surgical site of patient in the progress of surgery by vision and sound information. In order to solve this limited information, the haptic function is necessary. And haptic surgical robot is also necessary to design a haptic master device. The master device for laparoscope operation with cable-conduit was developed in previous research to give haptic function. It suggested a possibility of developing a master device by using the cable-conduit. However, it is very inconvenient to use. Therefore, this paper suggests a new mechanism design structure to solve the problems of the previous work by new forming a new master device. And it has proved that it's usability is better than previous one. Furthermore it has also experimented and analyzed that a backlash of new master device is compensated by smooth backlash inverse algorithm.

• Smart Structures and Systems
• /
• v.11 no.4
• /
• pp.349-364
• /
• 2013

Recently, researchers in the field of structural health monitoring (SHM) have been rigorously striving to replace the conventional NDE techniques with the smart material based SHM techniques, employing smart materials such as piezoelectric materials. For instance, the electromechanical impedance (EMI) technique employing piezo-impedance (lead zirconate titanate, PZT) transducer is known for its sensitivity in detecting local damage. For practical applications, various external factors such as fluctuations of temperature and loading, affecting the effectiveness of the EMI technique ought to be understood and compensated. This paper aims at investigating the damage monitoring capability of EMI technique in the presence of axial stress with fixed boundary condition. A compensation technique using effective frequency shift (EFS) by cross-correlation analysis was incorporated to compensate the effect of loading and boundary stiffening. Experimental tests were conducted by inducing damages on lab-sized aluminium beams in the presence of tensile and compressive forces. Two types of damages, crack propagation and bolts loosening were simulated. With EFS for compensation, both cross-correlation coefficient (CC) index and reduction in peak frequency were found to be efficient in characterizing damages in the presence of varying axial loading.

• Journal of the Korean Society of Safety
• /
• v.26 no.5
• /
• pp.89-98
• /
• 2011

Work-related musculoskeletal disorders (WMSDs) have become a hot issue in the Korean workplace for the past several years. So many manufacturing companies have tried to improve the work environments for the control and the prevention of the WMSDs. This study investigates the relation between WMSDs and job stress from 965 workers in a shipbuilding company by questionnaire analysis. The seven job stress factors which are job autonomy, job insecurity, organizational system, workplace culture, unfair compensation, relationship conflict, and job requirement were analyzed. The prevalence of musculoskeletal disorders symptoms were 12.9%. The analysis showed that job stress by job autonomy was higher than that by job stress factor. WMSDs were associated with job requirement, organizational system, unfair compensation and workplace culture. The results could be used to design the management program for the reduction of job stress.

• The Journal of Asian Finance, Economics and Business
• /
• v.10 no.2
• /
• pp.195-201
• /
• 2023

Since the banking industry relies so heavily on strong customer-staff interactions, measuring employee job satisfaction has become a critical problem. To achieve benefits for both individuals and organizations, it is crucial to foster and ensure employee job satisfaction. The main objective of this study is to determine the influencing factors of employees' job satisfaction in commercial banks in Bangladesh. This study focused on some significant factors such as employee empowerment, job security, management support, and attractive compensation in an organization. In terms of research purpose, non-probability convenience sampling has been used, and the study is quantitative in nature. For data collection purposes, an online survey questionnaire was prepared based on previously published articles. The targeted population was the bank employees of commercial banks in Bangladesh where the final sample size was n = 200. For analyzing the collected data, SPSS 26.0 version has been used to test the study model and the proposed hypotheses. This study also shows that employee empowerment, job security, management support, and attractive compensation have positive and significant effects on employees' job satisfaction at the workplace. Finally, this study has offered some extraordinary directions and implications for future research on commercial bank authorities in Bangladesh.

• Journal of the Korean Society of Food Culture
• /
• v.24 no.2
• /
• pp.172-180
• /
• 2009

The purpose of this study was to investigate the consumer characteristics in foodservice according to university students' lifestyles. The data were collected by the questionnaire survey of 520 university students from Daegu Gyeongbuk Province. The SPSS/Win 12.0 program was used to analyse the samples. The results are as follows: 1) Lifestyle was divided into 10 factors and 3 clusters, namely "Convenience Intention" (cluster I), "Health Information Intention" (cluster II), and "Gender Equality Intention" (cluster III). 2) The differences in general characteristics between the three clusters were founded on gender, frequency of visits, companion, information type, and the type of restaurant. 3) The characteristics of cluster I (Convenience Intention) are explained by it consisting of the group with low averages in consumer dissatisfaction, complaints, compensation, and repurchase intention, where as cluster II was the high average group and cluster III the middle average group. Based on these results, consumer characteristics in foodservice are discussed.