• Current Optics and Photonics
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• v.6 no.3
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• pp.332-336
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• 2022

Given a cubic space, it is easy to uniformly illuminate the floor with light sources placed on top. However, little has been reported about uniform illumination on walls with the same configuration of light sources. Here we present a luminaire consisting of nine light-emitting diodes (LEDs) with perfect Lambertian distribution, placed on the top as a 3 × 3 rectangular LED array. The distances between LEDs and tilt angles of each individual LED are adjustable and optimized by an annealing algorithm. After optimization, the array produces a rectangular illumination pattern on one wall with a uniformity of about 89%. Analysis shows that the tilt angles of individual LEDs are key parameters for uniform side illumination. In a scenario that is more practical, the tilt angles of all the LEDs are set to be the same, only decreasing the uniformity to 83%.

• Advances in Computational Design
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• v.2 no.4
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• pp.257-271
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• 2017

There are many plain concrete arch bridges in Iran that have been used as railway bridges for more than seventy years. Owe to the fact that these bridges have not been designed seismically, and even may be loaded under high-speed trains, evaluation of fundamental frequencies of the bridges against earthquake and high-speed train vibrations is necessary for considering dynamics effects. To evaluate complex behavior of these bridges, results of field tests are useful. Since it is not possible to perform field tests for all arch bridges, these structures should be simulated correctly by computers for structural assessment. Several parameters are employed to describe the bridges, such as number of spans, length of spans, geometrical and material properties. In this study, results of field tests are used for modal analysis and adapted for 64 three dimensional finite element models with various physical parameters. Computer simulations show length of spans has important effect on fundamental frequencies of plain concrete arch bridge and modal deformations of bridges is in longitudinal and transverse directions. Also, these results demonstrate that fundamental frequencies of bridges decrease after increasing span length and number of spans. Plus, some relations based in the number of spans (n) and span length (l) are proposed for calculation of fundamental frequencies of plain concrete arch bridge.

• Earthquakes and Structures
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• v.6 no.2
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• pp.201-216
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• 2014

Many building codes use the empirical equation to determine fundamental period of vibration where in effect of length, width and the stiffness of the building is not explicitly accounted for. Also the equation, estimates the fundamental period of vibration with large safety margin beyond certain height of the building. An attempt is made to arrive at the simple empirical equations for fundamental period of vibration with adequate safety margin, using soft computing technique of Genetic Programming (GP). In the present study, GP models are developed in four categories, varying the number of input parameters in each category. Input parameters are chosen to represent mass, stiffness and geometry of the buildings directly or indirectly. Total numbers of 206 buildings are analyzed out of which, data set of 142 buildings is used to develop these models. It is observed that GP models developed under B and C category yield the same equation for fundamental period of vibration along X direction as well as along Y direction whereas the equation of fundamental period of vibration along X direction and along Y direction is of the same form for category D. The equations obtained as an output of GP models clearly indicate the influence of mass, geometry and stiffness of the building over fundamental period of vibration. These equations are then compared with the equation recommended by other researcher.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.51 no.4
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• pp.175-182
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• 2002

This paper proposes an analytic method for measuring the accurate fundamental frequency component of a fault current signal distorted with a DC-offset, a characteristic frequency component, and harmonics. The proposed algorithm is composed of four stages: sine filer, linear filter, Prony's method, and measurement. The sine filter and the linear filter eliminate harmonics and the fundamental frequency component, respectively. Then Prony's method is used to estimate the parameters of the DC-offset and the characteristic frequency component. Finally, the fundamental frequency component is measured by compensating the sine-filtered signal with the estimated parameters. The performance evaluation of the proposed method is presented for a-phase to around faults on a 345 kV 200 km overhead transmission line. The EMTP is used to generate fault current signals under different fault locations and fault inception angles. It is shown that the analytic method accurately measures the fundamental frequency component regardless of the characteristic frequency component as well as the DC-offset.

• Phonetics and Speech Sciences
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• v.9 no.1
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• pp.41-47
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• 2017

The main advantage of the statistical parametric speech synthesis is its flexibility in changing voice characteristics. A personalized text-to-speech(TTS) system can be implemented by combining a speech synthesis system and a voice transformation system, and it is widely used in many application areas. It is known that the fundamental frequency and the spectral envelope of speech signal can be independently modified to convert the voice characteristics. Also it is important to maintain naturalness of the transformed speech. In this paper, a speech synthesis system based on Hidden Markov Model(HMM-based speech synthesis, HTS) using the STRAIGHT vocoder is constructed and voice transformation is conducted by modifying the fundamental frequency and spectral envelope. The fundamental frequency is transformed in a scaling method, and the spectral envelope is transformed through frequency warping method to control the speaker's vocal tract length. In particular, this study proposes a voice transformation method using the correlation between fundamental frequency and vocal tract length. Subjective evaluations were conducted to assess preference and mean opinion scores(MOS) for naturalness of synthetic speech. Experimental results showed that the proposed voice transformation method achieved higher preference than baseline systems while maintaining the naturalness of the speech quality.

• Journal of Korean Academy of Fundamentals of Nursing
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• v.25 no.1
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• pp.33-45
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• 2018

Purpose: Objectives of this study were to identify and describe cultural meaning for nursing students in the class in fundamental nursing practice. Methods: Data were collected from November 2016 to May 2017 included focus group interviews and participants observation. The key informants in this study included 23 nursing students divided into 3 focus groups who had taken the course in fundamental nursing practice in university U and university S in Kyungpook, and university D in Jeonnam. Interviews continued until no new information could be identified from transcripts. Data were analyzed using the taxonomic analysis method developed by Spradley. Results: Based on the data acquired from the interviews, cultural domains in the class "fundamental nursing practice" were classified as 'community oriented activities', 'learning and playing space', 'relationship of difference and discrimination', 'time for present and future'. Conclusion: The culture in the class "fundamental nursing practice" could be summarized as 'non-standardized learning with team dynamics'. Also nursing students learned about a small society whose members are becoming nurses. Results indicate that it is critical for professors to understand students' values, beliefs and their attitude in order to aid in adjustment to class.

• Journal of Korean Academy of Fundamentals of Nursing
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• v.21 no.3
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• pp.292-301
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• 2014

Purpose: The purpose of this study was to contribute to the development of efficient methods of nursing practice education by evaluating effects of core fundamental nursing skills education on self-efficacy, clinical competence and practice satisfaction in nursing students. Method: The research design was a one group pretest-posttest design and it was done to assess changes in self-efficacy and clinical competence from pre to the post-test which was given after the core fundamental nursing skills education was completed. Data were collected from September 5 to December 20, 2013 from 156 nursing students who were taking the 12-hours core fundamental nursing skills education at one university in Gyeonggi-do. This practicum was composed of 6 core fundamental nursing skills. Results: Self-efficacy and clinical competence scores improved. There was no significant difference in self-efficacy but there was a significant difference of clinical competence. In the subscales of clinical competence, the domain of nursing skill was scored the highest. The score for practice satisfaction was also high. Conclusion: The results indicate that the core fundamental nursing skills education is effective in improving clinical competence and practice satisfaction in nursing students. But new strategies are needed to improve self-efficacy.

• Journal of Korean Academy of Fundamentals of Nursing
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• v.26 no.2
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• pp.107-116
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• 2019

Purpose: The purpose of this study was to identify factors with nursing students's confidence in performing fundamental nursing skills. The focus was on professionalism and self-efficacy. Method: For the sample 258 fourth graders of nursing students were recruited in two universities located in Gyeongnam or Ulsan. Data were analyzed using t-test, Pearson's correlation coefficients, and hierarchical multiple regression. Results: The mean score for confidence in performing fundamental nursing skills was $3.71{\pm}0.58$. Nursing professionalism and self-efficacy were positively correlated with confidence in performing fundamental nursing skills. Analysis using multiple regression showed that 27% of factors predicting confidence in performance of fundamentals of nursing practice (F=16.43, p<.001) included nursing professionalism (${\beta}=.37$, p<.001), self-expression (${\beta}=.15$, p=.009), and self-efficacy (${\beta}=.14$, p=.029). Conclusion: Findings show that nursing professionalism is one of the major factors influencing confidence in performing fundamental nursing skills. In order to improve the confidence in performing fundamental nursing skills, it is necessary to establish effective educational strategies that firmly enhance nursing professionalism and improve self-efficacy in nursing students.

• Nuclear Engineering and Technology
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• v.54 no.1
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• pp.293-300
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• 2022

During the decommissioning of the nuclear facilities, the radioactive gases in pressure vessels may leak due to the demolition operations. The decommissioning site has large space, slow air circulation, and many large nuclear facilities, which increase the difficulty of workers' inhalation exposure assessment. In order to dynamically evaluate the activity distribution of radionuclides and the committed effective dose from inhalation in nuclear decommissioning environment, an inhalation exposure assessment method based on the modified eddy-diffusion model and the inhaled dose conversion factor is proposed in this paper. The method takes into account the influence of building, facilities, exhaust ducts, etc. on the distribution of radioactive gases, and can evaluate the influence of radioactive gases diffusion on workers during the decommissioning of nuclear facilities.

• Ocean Systems Engineering
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• v.13 no.1
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• pp.57-77
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• 2023

In the present study, the total hydrodynamic pressure exerted by the fluid on walls of rectangular tanks due to horizontal excitations of different frequencies, is investigated by pressure based finite element method. Fluid within the tanks is invisid, compressible and its motion is considered to be irrotational and it is simulated by two dimensional eight-node isoparametric. The walls of the tanks are assumed to be rigid. The total hydrodynamic pressure increases with the increase of exciting frequency and has maximum value when the exciting frequency is equal to the fundamental frequency. However, the hydrodynamic pressure has decreasing trend for the frequency greater than the fundamental frequency. Hydrodynamic pressure at the free surface is independent to the height of fluid. However, the pressure at base and mid height of vertical wall depends on height of fluid. At these two locations, the hydrodynamic pressure decreases with the increase of fluid depth. The depth of undisturbed fluid near the base increases with the increase of depth of fluid when it is excited with fundamental frequency of fluid. The sloshing of fluid with in the tank increases with the increase of exciting frequency and has maximum value when the exciting frequency is equal to the fundamental frequency of liquid. However, this vertical displacement is quite less when the exciting frequency is greater than the fundamental frequency.