• Journal of the Ergonomics Society of Korea
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• v.33 no.4
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• pp.289-297
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• 2014

Objective: The purpose of this study is to identify the incidence risk of cardiovascular disease (CVD) in the workplace, and to suggest the prediction models for level of CVD incidence risk. Background: CVD can be caused by various factors related to personal habits such as diet and exercise, or genetics. However it can also be caused and aggravated by work, making the elimination of such risk factors at work crucial disease (KOSHA, 2013). Method: The distribution of CVD risk assessment levels of 162 workers was compared with the acquired medical examination data to discuss the necessity of assigning additional risk factors. Two alternative risk assessment models were given to enhance the accuracy of the evaluation; adjusting risk scores given in the KOSHA GUIDE H-1-2013 (alternative 1) and building a matrix of KOSHA GUIDE H-1-2013 and risk assessment results based on work condition levels (alternative 2). To verify the suggested models, medical examination results of 12 workers approved of convalescence were referred to. Results: The second alternative showed more relevance between the results and workers approved of convalescence in predicting the risk group when applied to actual heath examination data from the approved workers. The power of description of the new method for determining the risk of CVD incidence, 83.3%, is higher than that of KOSHA GUIDE H-1-2013, 25%. Conclusion: Results of this study imply that more approved workers had been from unmanaged normal groups than managed risk groups, raising the importance of CVD management. Application: The new prediction model considering working time and shift work developed in this study is expected to be a fundamental data for risk analysis and management of CVD in the workplace.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.9 no.6
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• pp.71-77
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• 2010

Although the problems of defects and nonmetallic inclusion in metal fatigue are very complicated, it is particularly important to view these problems from the perspective that defects and inclusions are virtually equivalent to small cracks. This concept will help one to understand various fatigue phenomena caused by Ductile Cast Iron. For different ferrite-pearlite matrix structure, containing more than 90% spheroidal ratio of graphite, GCD 45-3, GCD 50, GCD 60 series and 70%, 80%, 90% spheroidal ratio of graphite, GCD 40, GCD 45-1, GCD 45-2 series, this paper has carried out image analyzer, estimated maximum and mean size of graphite, investigated correlation. It was concluded as follows. (1) A good quality of Ductile cast iron using in this experiment, the graphite was separated well. The effect of the interaction by graphite was verified by microscopic observation and by fracture mechanics investigation in surface, interior of the specimen. (2)${\sqrt{area}}_{max}$ of graphite can be used to predict fatigue limit of Ductile Cast Iron. The Statistical distribution of extreme values of ${\sqrt{area}}$ may be used as a guide line for the control of inclusion size in the steel making processes.

• International Journal of Contents
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• v.12 no.4
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• pp.31-44
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• 2016

Knowledge creation and management are regarded as critical success factors for an organization's survival in the knowledge era. As a process of knowledge acquisition and sharing, organizational learning mechanisms (OLMs) guide the learning function of organizations represented by its different learning activities. We examined a variety of learning processes that constitute OLMs. In this study, we aimed to capture the process and framework of OLMs and knowledge sharing and acquisition. Factors facilitating OLMs were investigated at three levels: individual, group, and organizational. The concept of an OLM has received some attention in the field of organizational learning, however, the relationship among the factors generating OLMs has not been empirically tested. As part of the ongoing discussion, we attempted a systemic approach for OLMs. OLMs can be represented by factors that are inherent to the organization's system; therefore, prior to empirically testing the OLM generating factor(s), evaluation of its organizational integration is required to determine effective treatment of each factor. Thus, we developed a framework to manage knowledge and proposed a method to numerically evaluate factors influencing the OLMs. Specifically, composite importance (CI) of the Decision-Making Trial and Evaluation Laboratory (DEMATEL) method was applied to explore the interaction effect of these factors based on systemic approach. The augmented matrix thus generated is expected to serve as a stochastic matrix of an absorbing Markov chain.

• Safety and Health at Work
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• v.12 no.4
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• pp.424-431
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• 2021

Background: This study aims to introduce the formulation of the regulation for the selection of respirators for accident preparedness chemicals (APCs) according to chemical workplace situations and to determine on-site applicability. Methods: Workplaces were grouped into seven work categories, and APCs were classified into six groups to select adequate respirators. A survey was conducted to enhance the understanding of work situations and adequate respirators. The total number of subjects surveyed in 2018 was 201 managers and handlers, and that in 2019 was 91 handlers and 204 managers. Results: Adequate respirators were allocated to each cell using the matrix method. The study observed an overall lack of understanding of work situations, especially in the operation of open devices, which was the highest at 32.7%. Despite its implementation in 2015, 17.6% and 25.0% of the managers and APCs handlers, respectively, were unaware of the regulations for selecting respirators. Only 70.4% of the APCs handler wore respirators in compliance with regulations. Conclusion: The method for selecting respirators according to work situations using the matrix method is considered reasonable. Thus, this study suggests that the development of educational contents and reinforcing education should be essential steps to increasing awareness of regulations.

• Mass Spectrometry Letters
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• v.14 no.4
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• pp.166-172
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• 2023

The utilization of methyl 2-aminobenzoate as a biocide and pesticide has raised concerns regarding its potential toxicity. To assess its safety, it is crucial to determine its quantity and related toxicity using reference materials (RMs) or certified reference materials (CRMs). As an RM and CRM containing methyl 2-aminobenzoate within a biocidal product matrix is currently unavailable, this study aimed to produce a high-quality RM containing methyl 2-aminobenzoate, ensuring its homogeneity and stability, following the ISO Guide 35 and ISO 17034. The study determined that the produced RM exhibited homogeneity, as indicated by a calculated F-value (1.91) smaller than the critical F-value (3.02). In the assessment of isochronous short-term stability, the slope of the linear regression for the RM showed no statistically significant difference from zero when stored at temperatures of 4, 18, and 60 ℃ for 4 weeks. Regarding classical long-term stability, the RM demonstrated sustained stability over the course of one year when stored at 4 ℃. This study has successfully developed an RM for monitoring methyl 2-aminobenzoate in biocides and pesticides. Its quality underwent rigorous evaluation, confirming both homogeneity and stability.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2001.10a
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• pp.196-201
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• 2001

Very Large Floating Structures have been planned for effective utilization of ocean space in recent years. The VLFS usually has a control tower to guide airplane securely. This paper present an effective method for calculating the wave induced hydroelastic responses of VLFS considering the effect of control tower-shapes. The source and dipole distribution method is used to calculate the hydrodynamic loads and equation of motion is derived by considering the static and dynamic coupling effects from different segments of the plate. The rigidity matrix for VLFS is formulated by finite element method using a plate theory. The calculated results for VLFS with a control tower are compared with those for VLFS without a control tower.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• v.14 no.1
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• pp.35-42
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• 2010

A goal of Magnetic Resonance Imaging is reproducing a spatial map of the effective spin density from the measured Fourier coefficients of a specimen. The imaging procedure can be done by inverse Fourier transformation or backward fast Fourier transformation if the data are sampled on a regular grid in frequency space; however, it is still a challenging question how to reconstruct an image from a finite set of Fourier data on irregular points in k-space. In this paper, we describe some mathematical and numerical properties of imaging techniques from non-uniform MR data using the pseudo-inverse or the diagonal-inverse weight matrix. This note is written as an easy guide to readers interested in the non-uniform MRI techniques and it basically follows the ideas given in the paper by Greengard-Lee-Inati [10, 11].

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2002.04a
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• pp.10-13
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• 2002

Pogo is the instability resulting from the interaction between rocket structure and propulsion system of liquid propellant rocket. The coupling of structure and propulsion system can lead to severe problem in rocket. For the analysis of pogo, a time-invariant linearized mathematical model is developed for a selected flight time. Propulsion system is modeled using element representations for each components. The constitutive equation of propulsion system is a homogeneous second-order equation form in the Laplace domain. Rocket structure is modeled using FEM. From the results of modal analysis of structure, the behavior of structure can be represented. System equations for coupling structure and propulsion system are composed of all propulsion system equations and vehicle motion equations reacting on the vehicle by each component of propulsion system. The stability is obtained by the eigen solution of system matrix. The optimization of the design variables such as size, place of accumulator for suppressing pogo instability is carried out. This article of study can be used to determine the degree of stability, and guide the design of pogo suppression system.

• Journal of the Korean Institute of Telematics and Electronics
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• v.20 no.6
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• pp.52-57
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• 1983

We report a theoretical study on wave propagation in magneto-optic thin-film waveguides. The field distribution and phase velocity of the guided hybrid modes are analyzed in terms of the phase difference of basic system modes and the Faraday rotation of the magneto-optic thin film. Splitting of the phase constant curves due to the F araday rotation is discussed. The present hybridmode analysis leads to a conversion matrix which shows that the distance dependence of the mode conversion in the guide is different from that in the bulk medium.

• Journal of Ocean Engineering and Technology
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• v.16 no.2
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• pp.32-37
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• 2002

Very Large Floating Structures have been planned for effective utilization of ocean space in recent years. The nonerctangular VLFS usually has a control tower to guide airplane securely. This paper presents an effective method for calculating the wave induced hydroelastic responses of VLFS considering the effect of control tower-shapes. The source and dipole distribution method is used to calculate the plate. The rigidity matrix for VLFS is formulated by finite element method using a plate theory. The calculated results for nonerctangular VLFS with a control tower are compared with those for VLFS without a control tower.