• Journal of the Korean Society of Safety
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• v.24 no.6
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• pp.55-62
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• 2009

After examining the characteristics of the heat decomposition of the 80~120mesh flour using the Mini cup pressure vessel test and determining the apparent activation energy in a spontaneous combustion, the conclusion is as follows. The heat decomposition of flour occurs at around $100^{\circ}C$ and the peak for the maximum rise in pressure appears at around $290^{\circ}C$. The decomposition pressure against various temperature in the vessel shows the maximum value of $4.7kg/cm^2$ approximately at $440^{\circ}C$. When the thickness of the sample is 3cm, the maximum temperature and the critical temperature of ignition are $398^{\circ}C$ and $204.5^{\circ}C$, respectively; the critical temperature is $194.5^{\circ}C$ when the thickness of the sample is 5cm, and $182.5^{\circ}C$ when the sample is 7cm. In addition, the apparent velocity calculated using the method of least squares is 35.0407Kcal/mol.

• Journal of Korean Critical Care Nursing
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• v.15 no.3
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• pp.1-11
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• 2022

Purpose : The purpose of this study was to not only examine the importance and performance status of patient safety nursing activities in the intensive care unit but also to understand nurses' educational needs in this respect. Methods : In this descriptive study, 196 nurses working in the intensive care units of university hospitals located at B City and G Province were enrolled. They completed the Importance-Performance Analysis (IPA) questionnaire, and the data were statistically analyzed. Results : Mean±standard deviation item scores of importance and performance of patient safety nursing activities were 4.75±0.33 and 4.48±0.38, respectively. In the IPA results, a total of 10 items were included in the second quadrant, including 1 item related to 'transfer,' 1 to 'infection,' and 1 to 'firefighting surveillance.' As the second quadrant contains the high-importance, low-performance items, these 10 items resemble the nurses' educational needs that should be prioritized. Conclusion : The results of this study can be used as a basis for the development of nursing educational programs for patient safety in the intensive care unit.

• International conference on construction engineering and project management
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• 2009.05a
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• pp.432-439
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• 2009

This research project was carried out to develop the technique to assess quantitatively and rapidly the stability of a tunnel by using the measured displacement at the tunnel construction site under excavation. To achieve this purpose, a critical strain concept was introduced and applied to an assessment of a tunnel under construction. The new technique calculates numerically the strains of the surrounding ground by using the measured displacements during excavation. A numerical practical system was developed based on the proposed analysis technique in this study. The feasibility of the developed analysis module was verified by incorporating the analysis results obtained by commercial programs into the developed analysis module. To verify the feasibility of the developed analysis module, analysis results of models both elastic and elasto-plastic grounds were investigated for the circular tunnel design. Then the measured displacements obtained in the field are utilized practically to assess the safety of tunnels using critical strain concept. It was verified that stress conditions of in-situ ground and ground material properties were accurately assessed by inputting the calculated displacement obtained by commercial program into this module for the elastic ground. However for the elasto-plastic ground, analysis module can reproduce the initial conditions more closely for the soft rock ground than for the weathered soil ground. The stability of tunnels evaluated with two types of strains, that is, the strains obtained by dividing the crown displacement into a tunnel size and the strains obtained by using the analysis module. From this study, it is confirmed that the critical strain concept can be fully adopted within the engineering judgment in practical tunnel problems and the developed module can be used as a reasonable tool for the assessment of the tunnel stability in the field.

• Journal of Korean Critical Care Nursing
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• v.10 no.1
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• pp.63-74
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• 2017

Purpose: The purpose of this study was to examine the effect of professional autonomy, organizational commitment, and perceived patient safety culture on patient safety management activities of nurses in medium and small-sized hospitals. Methods: A cross-sectional design was employed. Self-reported questionnaires were completed by 121 nurses with at least 3 months of working experience in medium and small-sized hospitals located in B city. Data were analyzed using descriptive statistics, a t-test, a one-way ANOVA, Pearson correlation coefficients, and a multiple regression analysis. Results: Professional autonomy (r=.22, p=.016), organizational commitment (r=.34, p<.001), and perceived patient safety culture (r=.55, p<.001) had a statistically significant positive correlation with patient safety management activities. The factors that might affect patient safety management activities were professional autonomy (${\beta}=.23$, p=.003) and perceived patient safety culture (${\beta}=.55$, p<.001). The explanatory power of these factors for patient safety management activities was 33.5% (F=21.19, p<.001). Conclusions: The development of repetitive and continuous education programs is needed to improve a nurse's professional autonomy and perceived patient safety culture.

• Proceedings of the KIEE Conference
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• 2008.04c
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• pp.158-160
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• 2008

Safety critical systems are those in which a failure can have serious and irreversible consequences. Nowadays digital technology has been rapidly applied to critical system such as railways, airplanes, nuclear power plants, and vehicles. The main difference between analog system and digital system is that the software is the key component of the digital system. The digital system performs more varying and highly complex functions efficiently compared to the existing analog system because software can be flexibly designed and implemented. The flexible design make it difficult to predict the software failures. This paper reviews safety standard and criteria for safety critical system such as railway system and suggests development methodology, ordering management and assessment process for railway software with more detail description.

• Proceedings of the KSR Conference
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• 2001.10a
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• pp.179-186
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• 2001

As the freight traffic becomes heavier, the high speed of existing freight cars is essential instead of the construction of a new railway. The high speed can be achieved by the design modifications of the freight bogie. In this paper, an analytical model of freight bogie including the lateral force between rail and the flange of wheel is developed to decide the critical speed, which activates a hunting motion and tells the running safety of freight bogie. The dynamic responses of the analytical model were compared with an experimental data from a running test of a freight bogie and showed good agreements between them. The analytical model is used to find the design modifications of the freight bogie by parameter studies. The results show that the reduction of wheelset mass ratio and the increase of the axle distance of the freight bogie can increase the critical speed, but the primary lateral stiffness has little effects on the critical speed. And this also study shows that smaller wheel conicity deteriorates the running safety of the freight car, which means the overhauling of the wheel of freight bogie should be done regularly.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.1014-1015
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• 2008

Safety critical systems are those in which a failure can have serious and irreversible consequences. Nowadays digital technology has been rapidly applied to critical system such as railways, airplanes, nuclear power plants, and vehicles. The main difference between analog system and digital system is that the software is the key component of the digital system. The digital system performs more varying and highly complex functions efficiently compared to the existing analog system because software can be flexibly designed and implemented. The flexible design make it difficult to predict the software failures. This paper reviews safety standard and criteria for safety critical system such as railway system and suggests development process, ordering management and assessment process for railway software with more detail description.

• Nuclear Engineering and Technology
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• v.55 no.3
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• pp.861-869
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• 2023

This article proposes a novel approach to measure the performance of Safety-Critical Systems (SCS). Such systems contain multiple processing nodes that communicate with each other is modeled by a Petri nets (PN). The paper uses the PN for the performance evaluation of SCS. A set of ordinary differential equations (ODEs) is derived from the Petri net model that represent the state of the system, and the solutions can be used to measure the system's performance. The proposed method can avoid the state space explosion problem and also introduces new metrics of performance, along with their measurement: deadlock, liveness, stability, boundedness, and steady state. The proposed technique is applied to Shutdown System (SDS) of Nuclear Power Plant (NPP). We obtained 99.887% accuracy of performance measurement, which proves the effectiveness of our approach.

• Proceedings of the Korean Nuclear Society Conference
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• 2005.10a
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• pp.1097-1098
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• 2005

• Journal of Korean Tunnelling and Underground Space Association
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• v.11 no.4
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• pp.403-410
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• 2009

This paper discusses an application method of critical strains concept for tunnels' safety by using the values of measured displacements which are obtained in the field. The aim of this paper is to: (1) study on the engineering meanings of critical strains concept by reviewing the previous researches and application examples with measured displacement values; (2) study on the engineering reasonability of critical strains concept with the view point of a tunnel engineering and a geotechnical engineering; (3) study on the features of ground deformation due to tunneling and reciprocal relation between total displacement and measured displacement; (4) evaluate a tunnel safety by using domestic measurements collected in the field; and (5) re-evaluate the control criteria which were previously used in the field, with the view point of critical strains concept. Consequently, it was confirmed that critical strains in the ground has a reasonability and a possibility of unified or common concept with the view point of a tunnel engineering.