• Journal of The Korean Society of Agricultural Engineers
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• v.63 no.1
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• pp.11-25
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• 2021

The objective of this study was to analyze the impact of activation functions on flood forecasting model based on Artificial neural networks (ANNs). The traditional activation functions, the sigmoid and tanh functions, were compared with the functions which have been recently recommended for deep neural networks; the ReLU, leaky ReLU, and ELU functions. The flood forecasting model based on ANNs was designed to predict real-time runoff for 1 to 6-h lead time using the rainfall and runoff data of the past nine hours. The statistical measures such as R2, Nash-Sutcliffe Efficiency (NSE), Root Mean Squared Error (RMSE), the error of peak time (ETp), and the error of peak discharge (EQp) were used to evaluate the model accuracy. The tanh and ELU functions were most accurate with R2=0.97 and RMSE=30.1 (㎥/s) for 1-h lead time and R2=0.56 and RMSE=124.6~124.8 (㎥/s) for 6-h lead time. We also evaluated the learning speed by using the number of epochs that minimizes errors. The sigmoid function had the slowest learning speed due to the 'vanishing gradient problem' and the limited direction of weight update. The learning speed of the ELU function was 1.2 times faster than the tanh function. As a result, the ELU function most effectively improved the accuracy and speed of the ANNs model, so it was determined to be the best activation function for ANNs-based flood forecasting.

• Tribology and Lubricants
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• v.38 no.3
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• pp.84-92
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• 2022

In Part I, developed was a method to obtain the stress field due to an edge dislocation that locates in an elastic half plane beneath the contact edge of an elastically similar square wedge. Essential result was the corrective functions which incorporate a traction free condition of the free surfaces. In the sequel to Part I, features of the corrective functions, F_kij,(k = x, y;i,j = x,y) are investigated in this Part II at first. It is found that F_xxx(ŷ) = F_xyx(ŷ) where ŷ = y/η and η being the location of an edge dislocation on the y axis. When compared with the corrective functions derived for the case of an edge dislocation at x = ξ, analogy is found when the indices of y and x are exchanged with each other as can be readily expected. The corrective functions are curve fitted by using the scatter data generated using a numerical technique. The algebraic form for the curve fitting is designed as F_kij(ŷ) = $\frac{1}{\hat{y}^{1-{\lambda}}I+yp}$$\sum_{q=0}^{m}{\left}$$\left[A_q\left(\frac{\hat{y}}{1+\hat{y}} \right)^q \right]$ where λ_I=0.5445, the eigenvalue of the adhesive complete contact problem introduced in Part I. To investigate the exponent of F_kij, i.e.(1 - λ_I) and p, Log|F_kij|(ŷ)-Log|(ŷ)| is plotted and investigated. All the coefficients and powers in the algebraic form of the corrective functions are obtained using Mathematica. Method of analyzing a surface perpendicular crack emanated from the complete contact edge is explained as an application of the curve-fitted corrective functions.

• Journal of Biomedical Engineering Research
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• v.28 no.5
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• pp.618-627
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• 2007

As our society progresses rapidly toward an aged society, there is a stiff increase in the population of the aged persons who have difficulties in adjusting themselves to environments due to declines of their physical functions. Therefore, there is a great need for the concept of 'Universal Design' that demands the design of overall social structure to care for the elderly. Due to this reason, the physical function of the aged persons should thoroughly be studied for the development of rehabilitation and training equipments to help the recovery of physical functions of the elderly. Among the variety of physical functions of the elderly, visual functions, motion characteristics, hearing functions, and somatosensory functions have significant influence toward everyday lives and are physical functions to study for the construction of urgently needed physical function databases of the elderly. This study concentrates on visual functions among the variety of physical functions of the elderly. To measure various visual functions of the elderly, a measurement room for the elderly has been developed, which can mimic everyday lives and perform measurements of visual functions with subjects in seated position. The measurement items for the construction of the database were capabilities in everyday vision according to changes in arrangement of colors and light intensity and capabilities in everyday vision, color distinction, dark adaptation, and light glare against changes in contrast.

• Journal of the Korean Society for Railway
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• v.20 no.1
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• pp.20-30
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• 2017

Due to the evolution of wireless communications technology, Long Term Evolution (LTE), which is a $4^{th}$ generation mobile communications system, has been adopted as a railway communications system. This LTE Railway (LTE-R) system is composed of various elemental functions, which are largely categorized into public safety and wireless communications for train control. Research on the public safety functions of railway communications have their roots in TRS based national public safety communication systems, and research on wireless communications functions for train control have their roots GSM-R, which is utilized by the ETCS in Europe. Based on these circumstances, this paper first analyzes the requirements for developing public safety technology in LTE-R, and compares those requirements with the functions of public safety LTE (PS-LTE), which is being deployed for the first time in the world by the South Korean government. Based on an analysis of the common and specific functions of LTE-R and PS-LTE, we conclude that there is little problem in integrating LTE-R and PS-LTE from the perspective of functionality. Second, this paper provides a comparison of the LTE-R requirements for the Quality of Service (QoS) with those of GSM-R utilized by the ETCS. This offers a guideline to allow LTE-R to be applied to a 500km/h train control system.

• ETRI Journal
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• v.35 no.3
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• pp.397-405
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• 2013

In this paper, two sets of spectrally efficient ultra-wideband (UWB) pulses using zinc and frequency-domain Walsh basis functions are proposed. These signals comply with the Federal Communications Commission (FCC) regulations for UWB indoor communications within the stipulated bandwidth of 3.1 GHz to 10.6 GHz. They also demonstrate high energy spectral efficiency by conforming more closely to the FCC mask than other UWB signals described in the literature. The performance of these pulses under various modulation techniques is discussed in this paper, and the proposed pulses are compared with Gaussian monocycles in terms of spectral efficiency, autocorrelation, crosscorrelation, and bit error rate performance.

• Korean Journal of Mathematics
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• v.19 no.1
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• pp.1-16
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• 2011

In this paper, using differential operator, we have introduce new class of p-valent uniformly convex functions in the unit disc U = {z : |z| < 1} and obtain the coefficient bounds, extreme bounds and radius of starlikeness for the functions belonging to this generalized class. Furthermore, partial sums $f_k(z)$ of functions $f(z)$ in the class $S^*({\lambda},{\alpha},{\beta})$ are considered. The various results obtained in this paper are sharp.

• Knowledge Management Research
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• v.17 no.3
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• pp.23-44
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• 2016

This study examined the cause-and-effect relationships among developmental network characteristics, developmental functions, and career identity. The study analyzed the data of employees with more than two years of experience and a college degree or over qualifications, from domestic companies. For analysis, the structural equation model was applied. Most of all, it was substantiated that the structural relationships among the developmental network characteristics, developmental functions, and career identity. The specific results were as follows. First, tie strength had a positive effect on all of developmental functions but psychosocial support mediated the relationship between the tie strength and career identity. Second, an indirect relationship between indicators of network diversity and identity was not found or the indirect relationship was very weak.

• Knowledge Management Research
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• v.11 no.3
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• pp.13-29
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• 2010

This study aims to investigate the effect of mentoring functions (career development, role modeling, and psychosocial function) on the motivation to adopt knowledge and the success of knowledge transfer in formal mentoring relations. There are considerable empirical investigation into the antecedents and consequences of mentoring, such as organizational commitment, organizational citizenship behavior, job satisfaction, In this paper, based on the relevant literatures, hypotheses are established and empirically tested that are about the effect of mentoring functions on the motivation to adopt knowledge, and the effect of motivation to adopt knowledge on the success of knowledge transfer. Using a sample of 287 service industry employees, the empirical results shows that career development and role modeling functions ware positively related to motivation to adopt knowledge, but psychosocial function was not significantly related. In addition, the motivation to adopt knowledge was positively related to the success of knowledge transfer. Based on these findings, implication and future direction are discussed.

• The Mathematical Education
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• v.47 no.3
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• pp.239-259
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• 2008

This paper is to find and to suggest alternative ways of description on function chapters in the middle school mathematics so that the descriptions be more closely related to daily life. The research has two phases: one for belief on the usefulness, the other for cognitive ability to solve the practical problems. Results are as following. 1. Most descriptions of corresponding chapters have emphases on the usefulness of functions so as to enhance beliefs on the use of functions. 2. Most practical functions contain expressions of large constant term and large coefficients in magnitude while those are not in the descriptions of tektbooks, especially in case of using ruled papers. 3. For quadratic functions, most students do not detect the degree of the function from the data presented by pairs of values of x and y. And those are not dealt with in most of textbooks, which are given in the MIC textbook.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.8 no.6
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• pp.80-91
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• 2005

This research aims to classify wetland types and evaluate functions of a dam lake. The case study area is Boryung lake in Boryung City. In this study was carried out based upon field surveys, drawing maps and publication, and modified-RAM which can evaluate the general functions and conservation values of wetlands. Eight functions of 2-12 variables each are analyzed for assessing the wetland functions. The analysis shows that several types of wetlands were identified, such as Palustrine/ Perennial/ Hydrophytes, Palustrine/ Perennial/ Openwater, Palustrine/ Seasonal/ Herbal, Palustrine/ Seasonal/ Shrub and Scrub, Palustrine/ Seasonal/ Hydrophye, and Riparian/ Seasonal/ Shrub in the Boryung lake. The average level of functions of the wetlands is very "HIGH", and it is recommended that prompt conservation measures should be taken.