• Journal of the Korea Safety Management & Science
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• v.10 no.4
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• pp.73-81
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• 2008

The current electrical safety plan developed for the national electricity system has been playing an important role in handling a variety of electrical accidents. However, it can be more effective to prevent or reduce those accidents if a preventive electrical safety plan is available. In this paper, an approach to developing the safety plan is described. We first discuss the contents that should be included in the plan. Noting that an effective plan requires the system level consideration of all the factors affecting the safety issues, an operation concept document (OCD) is considered. The OCD can allow us to understand the behavior of the safety system based on the operation environment, the system functions, the performance requirements, all at the system level of the safety system. Thus, the OCD can be useful in developing the safety plan. A detailed description then follows on how the OCD is developed for the electrical safety system under study. Finally, we discuss how the developed OCD can be used in deriving the preventive electrical safety plan.

• Geomechanics and Engineering
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• v.30 no.3
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• pp.273-280
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• 2022

A certain amount of random vibration excitation to subway track is caused by subway operation. This excitation is transmitted through track foundation, tunnel, soil medium, and ground building to the ground and ground structure, causing vibration. The vibration affects ground building. In this study, the results of ANSYS numerical simulation was used to establish back-propagation (BP) neural network model. Moreover, a back-propagation neural network model consisting of five input neurons, one hidden layer, 11 hidden-layer neurons, and three output neurons was used to analyze and calculate the vertical Z-vibration level of New Capital's ground buildings of Qingdao Metro phase I Project (Line M3). The Z-vibration level under different working conditions was calculated from monolithic roadbed, steel-spring floating slab roadbed, and rubber-pad floating slab roadbed under the working condition of center point of 0-100 m. The steel-spring floating slab roadbed was used in the New Capital area to monitor the subway operation vibration in this area. Comparing the monitoring and prediction results, it was found that the prediction results have a good linear relationship with lower error. The research results have good reference and guiding significance for predicting vibration caused by subway operation.

• Journal of the Korean Operations Research and Management Science Society
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• v.30 no.2
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• pp.143-156
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• 2005

Facility location planning (FLP) problem is the strategic level planning in supply chain. The FLP is significantly affected by the operation time of each facility. In most of the FLP researches, operation time of facility has been treated as a fixed value. However, the operation time is not a static factor in real situations and the fixed operation time may lead unrealistic FLP. In this paper, a mixed integer programming (MIP) model is proposed for solving the 3-stage FLP problem and operation times are adjusted by the results from the simulation model and an iterative approach combining the analytic model and simulation model is proposed to obtain more realistic operation plans for FLP problems.

• Nuclear Engineering and Technology
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• v.52 no.2
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• pp.308-322
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• 2020

This paper presents a conceptual design for a plant-wide autonomous operation system that uses artificial intelligence techniques. The autonomous operation system has the power and ability to perform the control functions needed for the emergency operation of a nuclear power plant (NPP) with reduced operator intervention. This paper discusses the emergency operation and level of automation in an NPP and presents the design requirements for an autonomous emergency operation system (A-EOS). Then, an architecture that consists of several modules is proposed, with descriptions of the functions. Finally, this paper introduces a prototype of the suggested autonomous system that integrates the authors' previous works.

• Journal of Korean Academy of Nursing Administration
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• v.20 no.1
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• pp.10-21
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• 2014

Purpose: This study was done to identify determinants of registered nurse (RN) skill mix and staffing level focused on hospital characteristics. Methods: Data were obtained from health insurance claims data and hospital reporting system in the Health Insurance Review and Assessment Service (HIRA) for the year 2010. Data from 2,998 hospitals were analysed using t-test, ANOVA, Pearson correlation, and regression analysis. Results: The RN skill mix and staffing level were positively related to hospital size and the percentage of inpatients to total patients. RN skill mix and staffing level were statistically different across regions. Including nursing aides (NA), however, there was no difference in staffing levels across regions. Medically vulnerable regions, bed operation rate, and the number of patients per doctor were also related to RN skill mix and staffing level. Conclusion: The statically significant determinants of RN skill mix and staffing level included hospital size, region, bed operation rate, percentage of inpatients, doctor-patient ratio. Further study needs to be done to investigate factors including RN supply and wages.

• Journal of Korea Water Resources Association
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• v.48 no.5
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• pp.379-391
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• 2015

Multi-functional weirs has been installed in four rivers are hydraulic structures across the river. The structures were divided into movable and fixed weirs. Hence, riverbed-level variation and sediment transport can be varied due to water gate operation. In this study, the long-term riverbed-level variation of Geum river basin due to water gate operation of multi-functional weirs was studied. Result of this study shows that the variation of thalweg elevation was greater than the variation of annual average riverbed elevation due to multi-functional weirs construction and water gate operation. Maximum riverbed degradation of thalweg elevation that occurred was 2.79m and riverbed aggradation was 1.90m. Maximum riverbed degradation of the annual average riverbed elevation that occurred was 2.16m and riverbed aggradation was 1.24m. Analysis result of flood stage by the variation of riverbed-level shows that flood stages were increased in majorities area. The maximum increase in the value of flood stage was 2.23m. For this reason, flood stages can be greater than the freeboard of the levees. Therefore, we should consider the water gate operation of multi-functional weirs when planning and managing sediment in the river. We are expecting to use the result of this study in river planning for river management and selecting the river regime.

• Journal of Chest Surgery
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• v.31 no.5
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• pp.494-501
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• 1998

From May 1, 1993 to May 31 1995, the authers studied retrospectively 211 patients who underwent cardiovascular operation with cardiopulmonary bypass(CPB). Because we were interested in new development of ARF(prevalence, mortality rate, and main risk factors), we performed a multivariate statistical analysis about data of patients with preoperative serum creatinine values of less than 1.5 mg/dL. Normal renal function before operation(serum creatinine level less than 1.5 mg/dL) was registered in 198(74%) patients. Of these, 27(14%) patients showed postoperative renal complication, including 20(10%) patients classified as renal dysfunction(serum creatinine level between 1.5 and 2.5 mg/dL) and 7(4%) patients as acute renal failure(serum creatinine level higher than 2.5 mg/dL). The mortality rate was 5.8% in normal patients, 5% in patients with renal dysfunction, and 43% when acute renal failure developed(p=0.036). Indeed, the renal impairment proved to be an independent predictor of mortality(odd ratio 2.52∼11.25), along with cardiovascular(odd ratio 4.20) and respiratory(odd ratio 2.18) complications. Multivariate analysis identified the following variables as independent risk factors for postoperative renal impairment : advanced age(odd ratio 1), need for emergency operation(odd ratio 3.78), low-output syndrome(odd ratio 3.66), respiratory complication(odd ratio 1.30), need for deep hypothermic circulatory arrest(odd ratio 1.4). The 13 patients(7%) with preoperative renal failure showed a significantly higher morbidity and mortality rate than those without renal complications before operation. We concluded that the likelihood of severe renal complications is resonably low in the patients undergoing cardiac operation without preexisting renal dysfunction, but associated mortality remains high. A prominant role of hemodynamic factor in the development of postoperative acute renal failure must be recognized during preoperative, intraoperative, and postoperative periods.

• The Korean Journal of Emergency Medical Services
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• v.11 no.3
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• pp.191-204
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• 2007

This study analyzes use and operation of silver ambulance with 110 patients who had used silver ambulance in Gwangju and Jeonnam regions from June of 2006 to June of 2007 and 53 paramedics who are involved directly in ambulance operation and the results of this analysis are as follows. 1. Users' health conditions, 69.1% of users answered as bad and 67.3% suffered from chronic diseases over 3 months and it was found that they used silver ambulance due to their bad health conditions. 2. Cronbach's alpha was 0.630 and family function index was generally reliable and solution was high as 1.60, but total points were low as 7.11 and it was considered that they had family troubles. 3. On the question of ambulance use, 44.5% answered they used it because it is free, 53.6% used it for appointed medical examination and treatment and 18.1% used it for emergency. 4. Degrees of satisfaction with ambulance and paramedics were 95.4% and 76.4% respectively and 80.0% of ambulance users answered ambulance arrived quickly within 15 min. 5. Correlation($x^2 $) between family or relative's residence and frequency of visits was 86.367 and its significance probability was 0.00 and it was found that it was significant in the level of 0.1%, but correlation($x^2 $) between visitors other than family or relatives and frequency of visits was 14.768 and its significance probability was 0.25 and it was found that it was not significant in the level of 5%. 6. Correlation($x^2 $) between transfer operation speed and mobilization time was found that it was not significant in the level of 5%. Correlation($x^2 $) between their own health condition purpose of ambulance use was 13.802 an 5.696 and its significance probability was 0.93 and it was found that it was not significant in the level of 1%, and it was considered because paramedics carried patients with safe operation.

• Women's Health Nursing
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• v.3 no.1
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• pp.72-81
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• 1997

The purpose of this study was to elucidate the effects of musical listening on anxiety in patients undergoing abdominal hysterectomy. On the basis of the research criterias, 46 patients were recruited from Kang-Nam St. Mary's Hospital in Seoul from October 1 to December 31, 1995. 20 patients of them were participated as the experimental group who received musical listening session with self-selected music tapes, while 26 patients as the control group who didn't receive that session. The musical listening sessions composed of 3 periods, the pre-operation evening, just before sleeping, the operation morning. There were no differences between two groups, in terms of age education, religion, the experience of operation, the perception of uterus, and the weight(%). The State-Trait Anxiety Inventory(STAI) was used to measure anxiety on all patients. And serum cortisol levels, fasting blood sugar levels, systolic and diastolic blood pressure were collected at the day before surgery and the operation day. The results were as follows : 1. There were no significant differences in State-Anxiety between the two groups. 2. The differences of serum cortisol level between the day before surgery and the operative day were significantly lower in experimental group than in control group(P=0.03). 3. The level of fasting blood sugar was significantly decreased in experimental group(P=0.01). 4. Systolic blood pressure level was significantly decreased in experimental group(P=0.02). While Diastolic blood pressure level was not significant between two groups. It is suggested imply that the musical listening during the perioperative period may alleviate the perioperative anxiety levels in patients undergoing abdominal hysterectomy.

• Journal of the Korean Society of Industry Convergence
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• v.26 no.5
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• pp.925-936
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• 2023

Currently, due to the rapid increase in power demand and the increase in capacity of power converters, the capacity of electromagnetic contactors is also increasing, and the burden on SMPS for the power that can drive them is increasing. Although the initial starting operation current of an electromagnetic contactor is significantly larger than the holding current for maintaining contact, most electromagnetic contactors apply the same voltage as the initial starting operation. An electromagnetic contactor must continuously apply a holding current to maintain the contact point, and the larger the capacity, the larger the current must be applied. This paper proposes a two-level magnetic contactor drive that allows setting the initial starting operation current to fully attach the contact point of the magnetic contactor and the holding current to maintain subsequent operation. In addition, a low-cost drive topology of analog and digital methods was proposed for various field applications, and an algorithm based on the ripple of the excitation current was proposed to determine whether the magnetic contactor was opened or closed without using a separate contact point. The feasibility of the proposed method was proven through Psim simulation experiments.