• Journal of Korean Society of Industrial and Systems Engineering
• /
• v.38 no.4
• /
• pp.177-183
• /
• 2015

Incremental sheet metal forming is a manufacturing process to produce thin parts using sheet metals by a series of small incremental deformation. The process rarely needs dedicated dies and molds, thus, preparation time for the process is relatively short as to be compared to conventional metal forming. Spring back in sheet metal working is very common, which causes critical errors in dimensions. Incremental sheet metal forming is not fully investigated yet. Hence, incremental sheet metal forming frequently produces inaccurate parts. This paper proposes a method to minimize dimensional errors to improve shape accuracy of products manufactured by incremental forming. This study conducts experiments using an exclusive incremental forming machine and the material for these experiments are sheets of aluminum AL1015. This research defines a process parameter and selects a few factors for the experiments. The parameters employed in this paper are tool feed rate, tool diameter, step depth, material thickness, forming method, dies applied, and tool path method. In addition, their levels for each factor are determined. The plan of the experiments is designed using orthogonal array $L_8$ ($2^7$) which requires minimum number of experiments. Based on the measurements, dimensional errors are collected both on the tool contacted surfaces and on the non-contacted surfaces. The distances between the formed surfaces and the CAD models are scanned and recorded using a commercial software product. These collected data are statistically analyzed and ANOVAs (analysis of variances) are drawn up. From the ANOVAs, this paper concludes that the process parameters of tool diameter, forming depth, and forming method are the significant factors to reduce the errors on the tool contacted surface. On the other hand, the experimental factors of forming method and dies applied are the significant factors on the non-contacted surface. However, the negative forming method always produces better accuracy than the positive forming method.

• Transactions of Materials Processing
• /
• v.31 no.6
• /
• pp.351-364
• /
• 2022

The yield criterion, or called yield function, plays an important role in the study of plastic working of a sheet because it governs the plastic deformation properties of the sheet during plastic forming process. In this paper, we propose a modified version of previous anisotropic yield function (Trans. Mater. Process., 31(4) 2022, pp. 214-228) based on J2 and J3 stress invariants. The proposed anisotropic yield model has the 6th-order of stress components. The modified version of the anisotropic yield function in this study is as follows. f(J₂⁰,J₃⁰) ≡ (J₂⁰)³ + α(J₃⁰)² + β(J₂⁰)^3/2 × (J₃⁰) = k⁶ The proposed anisotropic yield function well explains the anisotropic plastic behavior of various sheets such as aluminum, high strength steel, magnesium alloy sheets etc. by introducing the parameters α and β, and also exhibits both symmetrical and asymmetrical yield surfaces. The parameters included in the proposed model are determined through an optimization algorithm from uniaxial and biaxial experimental data under proportional loading path. In this study, the validity of the proposed anisotropic yield function was verified by comparing the yield surface shape, normalized uniaxial yield stress value, and Lankford's anisotropic coefficient R-value derived with the experimental results. Application for the proposed anisotropic yield function to AA6016-T4 aluminum and DP980 sheets shows symmetrical yielding behavior and to AZ31B magnesium shows asymmetric yielding behavior, it was shown that the yield locus and yielding behavior of various types of sheet materials can be predicted reasonably by using the proposed anisotropic yield function.

• Journal of Convergence for Information Technology
• /
• v.11 no.10
• /
• pp.115-130
• /
• 2021

This study is to study the overall structural relationship between work-life balance(WLB), superior trust, workplace happiness, and organizational commitment. The goal of this study is to study how WLB and superior trust affect workplace happiness, how workplace happiness affects organizational commitment, and the mediating effect of workplace happiness. Survey data were collected from incumbents working in large companies and SMEs, validity and reliability of research items were reviewed, and research hypotheses were tested using path analysis. As a result of testing the research hypothesis, WLB and superior trust have a positive (+) effect on workplace happiness, and workplace happiness has a positive (+) effect on organizational commitment. Also, job satisfaction plays a role as a partial parameter between WLB, superior trust, and organizational commitment. Based on the hypothesis test results, it was confirmed that the higher the level of WLB and superior trust, the higher the level of work satisfaction. Based on the research results, a plan was suggested for Korean corporate members to achieve workplace happiness and organizational commitment.

• Journal of Korean Public Health Nursing
• /
• v.33 no.2
• /
• pp.188-199
• /
• 2019

Purpose: The aim of this study was to provide a person-job fit as the basis for a better job environment and human resource development by examining the causal relationships with the perceived organizational support and job satisfaction of 45 public health center nurses located in Gyeonggi Province. Methods: Frequency analysis, factor analysis, correlation analysis, path analysis, mediating effect, and moderating effect were verified for use by SPSS & AMOS 22 ver. to target to nurses located in Gyeonggi Province. Results: First, the person-job fit has a positive effect on the perceived organizational support and job satisfaction. Second, the perceived organizational support has a partial mediating effect. Third, there was no difference in verifying the moderating effect of full-time public servants and temporary public servants. Conclusion: This study examined the relationship among the person-job fit, job satisfaction as an organizational effectiveness, and the perceived organizational support of mediated effect for nurses working at public health centers. The nurses in government service containing permanent and temporal employees was the adjustment effect. The analysis results showed that the ability of public health center nurses to perform tasks related to person-job fit and the ability of the individual to perceived organizational support was high. In addition, and the job satisfaction was good.

• The Journal of Korean Institute of Information Technology
• /
• v.17 no.10
• /
• pp.57-63
• /
• 2019

Motion errors which are caused by several reasons, non-ideal path, errors of navigation systems, and radar system errors, have to be corrected. Motion compensation methods can compensate the motion error, but not exactly. To correct these residual errors, several autofocus methods are invented. A popular method is phase gradient autofocus (PGA). PGA does not assume specific circumstances, such as isolated point targets and shapes of errors. PGA is an iterative and adaptive method, so that the processing time is the main problem for the real time processing. In this paper, the improved method to select targets for PGA is proposed to reduce processing time. The variances of image pixels are used to select targets with high SNR. The processing of PGA with these targets diminishes the processing time and iterations effectively. The processed results with real radar data, obtained by flight tests, show that the proposed method compensates errors well, and reduce working time.

• Asia-Pacific Journal of Business
• /
• v.10 no.3
• /
• pp.69-93
• /
• 2019

There is a growing interest in researching new leadership and efficient organizational management due to the changes and spread of Information Communications Technologies (ICT) related organizations. Therefore, the purpose of this study is to examine the effect of leadership on organization in ICT R & D, and to follow the relationship between coaching leadership, leader member exchange (LMX), emotional intelligence of leaders, and organizational effectiveness. In order to verify this research problem, a total of 310 people were surveyed from employees working in the ICT R & D field. Reliability analysis of the measuring tool was tested on 80 pilot surveys in advance, and the final 285 data were used for empirical analysis excluding 25 unsatisfactory responses. For analysis, SPSS 22.0 program and AMOS were used to analyze the reliability, validity, path analysis, and control effects of the measurement tools. The findings demonstrate empirically the positive relationship between LMX and organizational effectiveness on coaching leadership in ICT R & D. In addition, by empirically verifying the effect that the emotional intelligence of the leader regulates the relationship between LMX, organizational effectiveness, and coaching leadership, then emotional intelligence of the leader can be usefully applied in ICT R & D. Furthermore, the demand for more in-depth research on coaching leadership, LMX, and emotional intelligence of leaders, which positively affects organizational effectiveness, was identified as demand for ICT R & D is increasing and horizontal and interactive leadership is needed.

• Explosives and Blasting
• /
• v.39 no.4
• /
• pp.1-11
• /
• 2021

In this study, the vibration data were obtained to analyze the vibration generated during dismantling of slab using the mechanical dismantling method. The obtained vibration data were classified according to the attachment device and then the waveform and dominant frequency analysis were performed. And the correlation was analyzed by the different methods of measuring the distance between the work section and the measurement point. As a result of the waveform analysis for each attachment device, there was little change in the phase of the vibration waveform and only the change in amplitude, which is the magnitude of the vibration velocity. And as a result of frequency analysis, the frequency band was lower when using a crusher method than a braker method and frequency band were close of the natural frequency of the structure to be dismantled. As a result of the correlation analysis, the separation distance was estimated a higher correlation when evaluated as the path through which the vibration propagates along the structure frame than the straight distance between the measurement point and the working section.

• Transactions of Materials Processing
• /
• v.31 no.4
• /
• pp.214-228
• /
• 2022

The yield criterion, or called yield function, plays an important role in the study of plastic working of a sheet because it governs the plastic deformation properties of the sheet during plastic forming process. In this paper, we propose a novel anisotropic yield function useful for describing the plastic behavior of various anisotropic sheets. The proposed yield function includes the anisotropic version of the second stress invariant J₂ and the third stress invariant J₃. The anisotropic yield function newly proposed in this study is as follows. F(J₂)+ αG(J₃)+ βH (J₂ × J₃) = k^m The proposed yield function well explains the anisotropic plastic behavior of various sheets by introducing the parameters α and β, and also exhibits both symmetrical and asymmetrical yield surfaces. The parameters included in the proposed model are determined through an optimization algorithm from uniaxial and biaxial experimental data under proportional loading path. In this study, the validity of the proposed anisotropic yield function was verified by comparing the yield surface shape, normalized uniaxial yield stress value, and Lankford's anisotropic coefficient R-value derived with the experimental results. Application for the proposed anisotropic yield function to aluminum sheet shows symmetrical yielding behavior and to pure titanium sheet shows asymmetric yielding behavior, it was shown that the yield curve and yield behavior of various types of sheet materials can be predicted reasonably by using the proposed new yield anisotropic function.

• Journal of the Korean Society of Environmental Restoration Technology
• /
• v.25 no.3
• /
• pp.47-62
• /
• 2022

The Ministry of Environment has been working to reduce the impact on biodiversity, ecosystems, and social costs caused by soil runoff from highland Agricultural fields by setting up non-point pollution source management districts. To reduce soil loss, runoff path reduction technology has been applied, but it has been less cost effective. In addition, non-point pollution sources cause environmental conflicts in downstream areas, and recently highland Agricultural fields are becoming vulnerable to climate change. The Ministry of Environment is promoting the optimal management plan in earnest to convert arable land into forests and grasslands, but since non-point pollution is not a simple environmental problem, it is necessary to approach it from the aspect of NbS(Nature-Based Solution). In this study, a scenario for applying the nature-based solution was established for three subwatersheds west of Haean-myeon, Yanggu-gun, Gangwon-do. The soil loss distribution was spatialized through GeoWEPP and the amount of soil loss was compared for the non-point pollution reduction effect of mixed forests and grasslands. When cultivated land with a slope of 20% or more and ginseng fields were restored to perennial grasslands and mixed forests, non-point pollution reduction effects of about 32% and 29.000 tons compared to the current land use were shown. Also, it was confirmed that mixed forest rather than perennial grassland is an effective nature-based solution to reduce non-point pollution.

• Journal of the Microelectronics and Packaging Society
• /
• v.29 no.2
• /
• pp.19-31
• /
• 2022

With the advent of technologies based on big data, the trend of electronics towards high performance and high integration density continues. However, this development of electronics suffers from overheating issues, which seriously threaten the reliability of the devices. To develop effective strategies for thermal management, it is crucial to accurately evaluate the temperature distribution and design the heat dissipation path within the device in the operating condition. This paper introduces thermoreflectance microscopy that can observe the temperature distribution of a device with high spatial and temporal resolutions in a non-contact way. Specifically, the working principle and various forms of thermoreflectance microscopy are presented along with the latest research trends to improve the temperature, space, and time resolutions. We further review several examples in which thermoreflectance microscopy is applied to investigate the temperature and thermal characteristics of electronic devices.