• The Transactions of the Korean Institute of Electrical Engineers A
• /
• v.50 no.2
• /
• pp.90-95
• /
• 2001

Electric arc furnaces (EAFs) has a process to cause the degradation of the electric power quality such as voltage flicker. In order to adequately understand and analyze the effects on the power system from these loads, obtaining an accurate representation of the characteristics of the loads is crucial. In this paper, a mixed chaotic EAF model to represent the low frequency and high frequency variations of the arc current respectively has been proposed. The Lorenz system may contribute to the low frequency components of arc current and the logistic equation may contribute to the high frequency components, and the proposed mixed model will be a combination of both Lorenz and logistic model. The concept of chaotic parameters, such as chaotic resistance, inductance of admittance has been also proposed for the characterization of arc furnace operation and the highly nonlinear physical processes. The power quality indices are calculated from the simulated waveforms and compared with the actual power quality indices statistics in order to illustrate the model's capabilities.

• Geotechnical Engineering
• /
• v.4 no.1
• /
• pp.37-48
• /
• 1988

This is a part of research projects to investigate the several significant statistical correlati- onships among the various physical and engineering properties of alluvial clayey deposits in the estuary area of the great fixe rivers through the South-West coastal districts where are expected to be developed as large ingustrial site or agricultual development projects. As a first trial, the statistical analyses through computer programs were carried out using the results of laboratory and field tests of 227 soil samples from the Seum-Jin river area. When the initial void ratio which plays crucial role to the settlement of foundation is more than 2.5, the compression indices of soil samples are remarkably scattered, but these indices, which are formulated as a general expression, tend to increase as increasing the clay content, liquid limit, plastic limit and initial void ratio.

• Journal of the Earthquake Engineering Society of Korea
• /
• v.23 no.6
• /
• pp.329-339
• /
• 2019

The strategy for the management of earthquakes is shifting from post recovery to prevention; therefore, seismic performance management requires quantitative predictions of damage and the establishment of strategies for initial responses to earthquakes. Currently, seismic performance evaluation for seismic management in Korea consists of two stages: preliminary evaluation and detailed evaluation. Also, the priority of seismic performance management is determined in accordance with the preliminary evaluation. As a deterministic method, preliminary evaluation quantifies the physical condition and socio-economic importance of a facility by various predetermined indices, and the priority is decided by the relative value of the indices; however, with the deterministic method it is difficult to consider any uncertainty related to the return-year, epicenter, and propagation of seismic energy. Also this method cannot support tasks such as quantitative socio-economic damage and the provision of data for initial responses to earthquakes. Moreover, indirect damage is often greater than direct damage; therefore, a method to quantify damage is needed to enhance accuracy. In this paper, a Seismic Risk Assessment is used to quantify the cost of damage of road facilities in Pohang city and to support decision making.

• Structural Engineering and Mechanics
• /
• v.86 no.5
• /
• pp.621-633
• /
• 2023

Stability analysis and support system estimation of the Beheshtabad water transmission tunnel is investigated in this research. A combination approach based on the rock mass rating (RMR) and rock mass quality index (Q) is used for this purpose. In the first step, 40 datasets related to the petrological, structural, hydrological, physical, and mechanical properties of tunnel host rocks are measured in the field and laboratory. Then, RMR, Q, and height of influenced zone above the tunnel roof are computed and sorted into five general groups to analyze the tunnel stability and determine its support system. Accordingly, tunnel stand-up time, rock load, and required support system are estimated for five sorted rock groups. In addition, various empirical relations between RMR and Q i.e., linear, exponential, logarithmic, and power functions are developed using the analysis of variance (ANOVA). Based on the significance level (sig.), determination coefficient (R²) and Fisher-test (F) indices, power and logarithmic equations are proposed as the optimum relations between RMR and Q. To validate the proposed relations, their results are compared with the results of previous similar equations by using the variance account for (VAF), root mean square error (RMSE), mean absolute percentage error (MAPE) and mean absolute error (MAE) indices. Comparison results showed that the accuracy of proposed RMR-Q relations is better than the previous similar relations and their outputs are more consistent with actual data. Therefore, they can be practically utilized in designing the tunneling projects with an acceptable level of accuracy and reliability.

• Nuclear Engineering and Technology
• /
• v.56 no.5
• /
• pp.1638-1653
• /
• 2024

Given the unpredictability of the occurrence of the earthquake and other potential disasters into consideration, the nuclear power plant may be confronted with beyond design-basis earthquake load in the future. The containment structure may be severely damaged under such severe earthquake loading, increasing the risk of containment concrete cracking and potential radioactive materials leaking. Moreover, initial damage caused by the earthquake may significantly alter the pressure performance of the containment under follow-up internal pressure. To compromise the dangers of beyond design-basis earthquake to the containment, an alternative of replacing the conventional concrete with fiber-reinforced concrete (FRC) to upgrade the seismic resistance capacity of the containment is attempted and thoroughly researched. In this study, the influence of various fiber types such as rigid fiber and mixed fiber is regarded to constitute fiber-reinforced PCCVs. The physical properties of traditional and fiber-reinforced PCCVs under earthquake ground motions are scientifically compared and identified by using traditional and proposed evaluation indices. The results indicate that both the traditional evaluation index (i.e. top displacement, stress, strain) and the proposed damage index are greatly reduced by the practice of fiber strengthening under earthquake ground motions.

• Korean Institute of Interior Design Journal
• /
• v.26 no.3
• /
• pp.45-54
• /
• 2017

A social phenomenon that occurs in a physical space is said to be a complex system. However, space syntax, which is commonly employed by researchers to identify such social phenomena, has various limitations in interpreting their complexity. On the other hand, agent-based modeling considers a variety of factors including the personality of the agent, objective-oriented work flows, estimation according to time flows and better prediction of space use through diverse parameters depending the situation, as well as the characteristics of the space. The agent-based method thus has the potentials to be developed as an alternative to space syntax techniques. In particular, discrete event driven simulation(DEVS), which is part of the agent-based modeling method, embraces the concept of networks just like space syntax, which allows a possible theoretical linkage in the future. This study suggests a procedural model of agent-based DEVS reflecting two different connection methods, i.e. connections between adjacent areas and those of the entire space, and attempts to identify the relationship between the local and regional indices of space syntax. A number of spaces were selected as examples-one for a preliminary experiment and eight modified for the main experiment-and space syntax and DEVS were applied to each of them. The comparative analysis of the results led to the conclusions as follows: 1) Adjacent connections were closely related to local indices, while the whole-space approach to regional indices. Local integration shows both characteristics. 2) Observation of the time flow model indicated a faster convergence with the range of 1 to 3-fold of the total time of one lap, with the error of less than 10%. 3) The heat map analysis showed more obvious characteristics of using the space for the entire space rather than adjacent connections. 4) Space syntax shows higher eligibility than ABM.

• Journal of Physiology & Pathology in Korean Medicine
• /
• v.22 no.6
• /
• pp.1354-1358
• /
• 2008

In Traditional Korean Medicine it is one of basic principle that personality reflects physical conditions. In both of personality and ordinary symptoms, there are some criteria used for diagnosis whether the patient is in cold or hot condition. We studied the relationship between the criteria of cold-hot shown in personality pattern and ordinary symptom pattern. And also analyzed the relativeness in four constitution type. 877 patients who had visited oriental medical hospital and had been confirmed their constitution by drug response were included in this study. Patients filled out the questionnaire composed of personality and ordinary symptom questions. We selected questions related to cold-hot patterns. Next we made personality cold-hot index(PCHI) and ordinary symptom cold-hot index(OSCHI). The two indices were compared and analyzed totally and from the viewpoint of 4 constitution types. The coefficient of correlation between two indices was not high. In Soemin the coefficient was 0.257, in three other constitution it was lower than 0.200 or negative. In Soemin both indices were lower (cold-biased), but in three other constitution no significant results were found. In Tae-emin OSCHI was higher (hot-biased) than PCHI, in Tae-yangin PCHI was higher than OSCHI significantly. Personality is not affected by cold-hot less than expected. The criteria used for diagnosis of cold-hot seems to be biased on Soemin's.

• Ocean Science Journal
• /
• v.43 no.1
• /
• pp.1-7
• /
• 2008

Physical and biological environmental variations in the East Sea were investigated by analysing time-series of oceanographic data and meteorological indices. From 1971 to 2000, dominant periodicity in water temperature variations had two apparent periods of 3 to 4 years and of decades, especially in the southwestern part of the East Sea affected by the influence of inflowing Tsushima warm current. Fluctuating water temperature within a certain period appears to respond to El $Ni{\tilde{n}}o$ events with a time lag. It was found that there was a strong correlation between water temperature and El $Ni{\tilde{n}}o$ events with a time lag of 1.5 and 5.5 years for periods of 3 to 6 years and of decades, respectively. Corresponding with El $Ni{\tilde{n}}o$ events, water temperature variability also showed strong correlation with shift and/or changes in biological and chemical environments of nutrient concentrations, zooplankton biomass, and fisheries. However, there also occurred a short-term periodicity of water temperature variations. Within a period of 1 to 4 years, a relatively short-term cycle of water temperature variation had strong correlation with other climate indices such as Pacific Decadal Oscillation and monsoon index. After comparing coherence and phase spectrum between water temperature and different climate indices, we found that there was a shift of coherent periods to another climate index during the years when climate regime shift was reported.

• The Korean Journal of Food And Nutrition
• /
• v.30 no.1
• /
• pp.83-95
• /
• 2017

This study examined the socioeconomic factors that affect self-rated health (SRH) in healthy adults, and the relationship of SRH to health-related habits, serum biochemical indices, and nutritional intakes. Subjects consisted of 1,154 healthy adults without any known disease, aged 19 to 65 years (average age of 36.7), whose information was obtained from the 2013 Korean National Health and Nutritional Examination Survey data. Of these subjects, 73 rated themselves as 'very healthy,' 460 indicated that they were 'healthy,' 568 self-identified as 'ordinary', and 53 put themselves in the 'unhealthy' category. The proportion of subjects who chose 'unhealthy' was significantly increased with higher frequencies of disruptions in their daily lives (p<0.05), regret after drinking (p<0.05), smoking (p<0.001), and higher levels of stress (p<0.001). On the other hand, the proportion of subjects reported as 'very healthy' was significantly higher with regular intense (p<0.001) or moderate physical activities (p<0.05), regular walking (p<0.05), a perception of being 'normal' in their body image (p<0.01), a decrease of body weight more than 3 kg in the past year (p<0.05), and without risk factors for metabolic syndrome (p<0.05). Serum triglyceride level was lower, and 25-(OH) vitamin D content was significantly higher, in the 'very healthy' group as compared to the 'unhealthy' group (p<0.05). Dietary fiber and vitamin C intakes were significantly higher in the 'very healthy' group than 'unhealthy' group (p<0.05). The overall results suggest that a healthy lifestyle, including regular exercise, non-smoking, good stress management, and higher intakes of fiber and vitamin C, may be potential factors that affect one's positive perception of health.

• Journal of Korean Biological Nursing Science
• /
• v.19 no.2
• /
• pp.51-59
• /
• 2017

Purpose: The purpose of this study was to identify the retention effects of an individualized dietary education program for hemodialysis patients on diet knowledge, diet self-care compliance, and physiological indices, thus to find the most effective time period for re-education. Method: This study utilized one-group repeated pretest-posttest design. The participants were 52 hemodialysis patients in C hospital, Gyeonggi-Do. Data were collected at 4 and 12 weeks after the education from January through April 2016. Results: There was significant increases in diet knowledge even 12 weeks after the education (p= .007). Diet self-care compliance showed a significant increase at 4 weeks (p= .001), but a decrease at 12 weeks after the education. The level of blood natrium was significantly decreased between 4 and 12 weeks after the education (p= .006). The weight was significantly decreased at 12 weeks after the education. Conclusion: It has been identified that re-education for hemodialysis patients should be implemented between 4 and 12 weeks after education in order to maintain patients' diet self-care compliance, an ultimate aim of diet education. By helping them with their self-care compliance, the patients would maintain their physical and psychological function optimally, thus contributing to a better quality of life among hemodialysis patients.