• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.18 no.3
• /
• pp.360-371
• /
• 1993

Flood search algorithm is known to be an effective routing mechanism for tactical application, since it provides high degree of survivability and robustness. But it is known that it has significant drawbacks with respect to the network efficiency [1]. We consider a tactical circuit-switched grid network with a maximum of four links and two priority classes of voice traffic, Using the minimum first-derivative length (MFDL) path, we improve the blocking probability performance of the circuit-switched network without increasing the call set-up time and processor loading of the algorithm.

• Journal of Ocean Engineering and Technology
• /
• v.11 no.4
• /
• pp.7-22
• /
• 1997

A finite element analysis is performed for lateral buckling problems on the basis of a geometrically nonlinear formulation for a beam with small elastic strain but with possibly large rotations. The total Lagrangian formulation for a general large deformation, which involves finite rotations, is chosen and the exponential map is used to treat finite rotations from the Eulerian point of view. For lateral buckling, the point of vanishing determinant of the resulting unsymmetric tangent stiffness is traced to examine its relationship to bifurcation points. It is found that the points of vanishing determinant is not corresponding to bifurcation points for large deformations in general, which suggests that the present unsymmetric tangent stiffness is not an exact first derivative of internal forces with respect to displacement. This is illustrated through several numerical examples and followed by appropriate discussion.

• The KSFM Journal of Fluid Machinery
• /
• v.2 no.1 s.2
• /
• pp.88-95
• /
• 1999

This paper introduces the part of efforts to develop a derivative type turboshaft engine from an existing baseline engine for multi-purpose helicopters aiming at 4000 kg of take-off weight for 10-12 passengers. As a first step in meeting the development goal of increasing the output power from 720 hp to 840hp with minimum modification, a two stage axial compressor was redesigned to obtain the higher pressure ratio by removing the inlet guide vane and increasing the chord length. As a result, a two stage axial compressor was designed to facilitate a flow rate of 3.04 kg/s, a pressure ratio of 2.01 and an adiabatic efficiency of $85\%$. Its performance tests were carried out and verification of test results and redesign are under progress. Aerodynamic and structural analyses of the preliminary design are mainly described in this paper.

• ETRI Journal
• /
• v.43 no.5
• /
• pp.881-890
• /
• 2021

Photoplethysmography (PPG) is a noninvasive technique that can be used to conveniently measure heart rate (HR) and thus obtain relevant health-related information. However, developing an automated PPG system is difficult, because its waveforms are susceptible to motion artifacts and between-patient variation, making its interpretation difficult. We use deep neural network (DNN) filters to mimic the cognitive ability of a human expert who can distinguish the features of PPG altered by noise from various sources. Systolic (S), onset (O), and first derivative peaks (W) are recognized by three different DNN filters. In addition, the boundaries of uninformative regions caused by artifacts are identified by two different filters. The algorithm reliably derives the HR and presents recognition scores for the S, O, and W peaks and artifacts with only a 0.7-s delay. In the evaluation using data from 11 patients obtained from PhysioNet, the algorithm yields 8643 (86.12%) reliable HR measurements from a total of 10 036 heartbeats, including some with uninformative data resulting from arrhythmias and artifacts.

• Honam Mathematical Journal
• /
• v.45 no.2
• /
• pp.184-197
• /
• 2023

For the numerous uses and significance of the Whittaker function in the diverse research areas of mathematical sciences and engineering sciences, This paper aims to introduce an extension of the Whittaker function by using a new extended confluent hypergeometric function of the first kind in terms of the Mittag-Leffler function. We also drive various valuable results like integral representation, integral transform and derivative formula. Further, we also analyze specific known results as a particular case of the main result.

• Natural Product Sciences
• /
• v.17 no.1
• /
• pp.10-13
• /
• 2011

As parts of our continuing search for biologically active compounds from medicinal plants, we investigated the constituents of the seeds of Amomum xanthioides and isolated a sesquiterpenoid, a nerolidol derivative from its MeOH extract. The chemical structure was determined by spectroscopic methods, including 1D and 2D NMR to be ($2S^*$,$2'R^*$,$5'S^*$)-2-(5'-ethenyltetrahydro-5'-methylfuran-2'-yl)-6-methylhept-5en-2-ol (1). Compound 1 was isolated for the first time from nature source. Compound 1 exhibited a good cytotoxicity against SK-OV-3 and SK-MEL-2 cells ($IC_{50}$: 16.7 and $8.6\;{\mu}M$, respectively) using a SRB bioassay. In this study, we also determined the absolute configuration of 2 reported in previous paper.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.65 no.8
• /
• pp.1383-1391
• /
• 2016

This paper is concerned with applicability of a new type of controllers, called i-PID and GPI in which unknown parts of the plant are taken into account without any modeling procedure, to automatic voltage regulator (AVR) system. First, the procedure for applying i-PID and GPI algorithms to AVR system is proposed, which uses model reduction technique based on the given information of AVR. Second, simulations are given to verify their effectiveness comparing to various PID algorithms including PIDD2 which is four-term controller, that is, consisting of PID and second order derivative terms. Superior response performances of i-PID and GPI in comparison to conventional PID controllers are shown. Moreover, i-PID can highly improve the system robustness with respect to model uncertainties, especially to load variations.

• Honam Mathematical Journal
• /
• v.43 no.1
• /
• pp.130-140
• /
• 2021

In this paper, we introduce and study the concept of trigonometrically quasi-convex function. We prove Hermite-Hadamard type inequalities for the newly introduced class of functions and obtain some new Hermite-Hadamard inequalities for functions whose first derivative in absolute value, raised to a certain power which is greater than one, respectively at least one, is trigonometrically quasi-convex convex. We also extend our initial results to functions of several variables. Next, we point out some applications of our results to give estimates for the approximation error of the integral the function in the trapezoidal formula.

• Journal of Microbiology and Biotechnology
• /
• v.25 no.9
• /
• pp.1442-1448
• /
• 2015

The flavonoid apigenin and its O-methyl derivative, genkwanin, have various biological activities and can be sourced from some vegetables and fruits. Microorganisms are an alternative for the synthesis of flavonoids. Here, to synthesize genkwanin from tyrosine, we first synthesized apigenin from p-coumaric acid using four genes (4CL, CHS, CHI, and FNS) in Escherichia coli. After optimization of different combinations of constructs, the yield of apigenin was increased from 13 mg/l to 30 mg/l. By introducing two additional genes (TAL and POMT7) into an apigenin-producing E. coli strain, we were able to synthesize 7-O-methyl apigenin (genkwanin) from tyrosine. In addition, the tyrosine content in E. coli was modulated by overexpressing aroG and tyrA. The engineered E. coli strain synthesized approximately 41 mg/l genkwanin.

• Journal of Institute of Control, Robotics and Systems
• /
• v.18 no.6
• /
• pp.608-611
• /
• 2012

This paper focuses on attitude stabilization performance improvement of the quadrotor flying robot. First, the dynamic model of quadrotor flying robot was estimated through PEM (Prediction Error Method) using experimental input/output data. And attitude stabilization performance was improved by increasing the generation frequency of PWM signal from 50 Hz to 500 Hz. Also, the controller is implemented using a standard PID (Proportional-Integral-Derivative) controller augmented with feedback on angular acceleration, allowed the gains to be significantly increased, yielding higher bandwidth. Improved attitude stabilization performance is verified by experiment.