• The Journal of the Acoustical Society of Korea
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• v.38 no.6
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• pp.710-715
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• 2019

A transmission line based bowed string model is built by analogizing a vibrating string to an electrical transmission line and implementing the calculation for the frictional bow-string force given by a digital bow into a circuit. The performance of the proposed model is demonstrated by showing that the velocity of the string at the bowing point from the proposed model is consistent with that from the finite difference form of the wave equation for a bowed string by the digital bow.

• Journal of The Korean Astronomical Society
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• v.29 no.spc1
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• pp.11-14
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• 1996

Super-inflation driven by dilaton/moduli kinetic energy is naturally realized in compactified string theory. Discussed are selected topics of recent development in string inflationary cosmology: kinematics of super-inflation, graceful exit triggered by quantum back-reaction, and classical and quantum power spectra of density and metric perturbations.

• Journal of KIISE
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• v.43 no.11
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• pp.1275-1280
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• 2016

Existing techniques for string similarity search first generate a set of candidate strings and then verify the candidates. The efficiency of string similarity search is highly dependent on candidate generation methods. State of the art techniques select fixed length q-grams from a query string and generate candidates using inverted lists of the selected q-grams. In this paper, we propose a technique to generate candidates using variable length grams of a query string and develop a dynamic programming algorithm that selects an optimal combination of variable length grams from a query string. Experimental results show that the proposed technique improves the performance of string similarity search compared with the existing techniques.

• The KIPS Transactions:PartA
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• v.16A no.5
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• pp.319-326
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• 2009

Since string operations were applied to computational biology area, various data structures and algorithms for computing efficient string operations have been studied. The longest common substring problem is an operation to find the longest matching substring in more than two strings, and maximal repeat of string problem is an operation to find substrings repeated more than once in the given string. These operations are importantly used in the string processing area such as pattern matching and likelihood measurement. In this paper, we present algorithms to compute the longest common substring of two strings and to find the maximal repeat of string using three-dimensional $n{\times}n{\times}n$ processors on RMESH(Reconfigurable MESH). Our algorithms have O(1) time complexity.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2001.04a
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• pp.135-139
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• 2001

This paper describes a string resonator that is used for the interrogation system of a Fiber Bragg Grating(FBG) strain sensor. The strain on the fiber piece is calculated from the measured frequency based on that the natural frequency of a string is a function of the applied absolute strain. Existing research considered a fiber as a string, but a fiber is not a string in the strict sense due to its bending stiffness, thus the fiber should be modeled as a beam accompanied with an axial force. In the vibration modeling, the relationship between the strain and the natural frequency is derived, and then the resonance condition is described in terms of both the phase and the mode shape for sustaining resonant motion. Several experiments verify the effectiveness of the proposed model of the fiber. The performance of the string resonator is analyzed by measuring the frequency change according to the applied strains in the dynamic range of 1100$\mu\varepsilon$ referred to the displacement from capacitance sensor. From the experimental results, the implemented string resonator provides the accuracy of $\pm$3$\mu\varepsilon$, the quasi-static resolution of ~0.1$\mu\varepsilon$(rms) which amount to be $\pm$0.17$\mu\textrm{m}$ and ~6nm respectively, in case of fiber length of 56mm. For a dynamic strain, it can provide the accuracy of ~3$\mu\varepsilon$ until the frequency comes to 8Hz. As a consequence, the string resonator proposed for FBG sensor provides the high accuracy and the high resolution in strain measurement, and also it is expecting to be used, for the application, to not only strain but also displacement measuring device.

• Journal of KIISE:Computer Systems and Theory
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• v.36 no.3
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• pp.135-139
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• 2009

The problems to compute the distances or similarities of multiple strings have been vigorously studied in such diverse fields as pattern matching, web searching, bioinformatics, computer security, etc. One well-known method to compare multiple strings in the given set is finding a consensus string which is a representative of the given set. There are two objective functions that are frequently used to find a consensus string, one is the radius and the other is the consensus error. The radius of a string x with respect to a set S of strings is the smallest number r such that the distance between the string x and each string in S is at most r. A consensus string based on radius is a string that minimizes the radius with respect to a given set. The consensus error of a string with respect to a given set S is the sum of the distances between x and all the strings in S. A consensus string of S based on consensus error is a string that minimizes the consensus error with respect to S. In this paper, we show that the problem of finding a consensus string based on radius is NP-complete when the distance function is a metric.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.54 no.3
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• pp.133-138
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• 2005

This paper presents a characteristics of horizontal swing angle in V type suspension string sets for 765kV T/L. The design of V type suspension string set does not differ from that of general string set for general towers, but it prevents instabilities from swing motion by the horizontal angle and by the wind pressure. We were designed specially 6 conductor yoke, arcing horn and earth horn. And we were decided to 550mm for a distance of strings. We were carried out characteristics of horizontal swing test and movement of mass center test for V-string sets of 400kN single, 300kN double and 400kN double. This products will be used for 765kV T/L of 1 circuit in suspension towers.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.28 no.1
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• pp.11-21
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• 2004

In this paper, an active vibration control of a tensioned elastic axially moving string is investigated. The dynamics of the translating string ale described by a non-linear partial differential equation coupled with an ordinary differential equation. The time varying control in the form of the right boundary transverse motions is suggested to stabilize the transverse vibration of the translating continuum. A control law based on Lyapunov's second method is derived. Exponential stability of the translating string under boundary control is verified. The effectiveness of the proposed controller is shown through the simulations.

• Proceedings of the KSME Conference
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• 2000.04a
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• pp.579-584
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• 2000

In this study. the time varying boundary control using the right boundary transverse motion on the basis of the energy flux between the moving string and the boundaries is suggested to stabilize the transverse vibration of an axially moving string. The effectiveness of the active boundary control is showed through experimental results. Sliding mode control is adopted in order to achieve velocity tracking control of the time varying right boundary to dissipate vibration energy of the string effectively. For the unmoving and moving string at various velocity under various tension the performance of the transverse vibration control using the time varying right boundary control with the suggested control scheme is experimentally demonstrated.

• Journal of KSNVE
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• v.9 no.5
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• pp.906-913
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• 1999

Time-dependent period and energy of free vibration of a string, whose length varies with time at a constant rate, are investigated by a traveling wave method. When the string length is increased, the vibration period increase, but the free vibration energy decrease with time. However, when the string undergoes retraction, the vibration energy increases with time. String tension together with non-zero instantaneous velocity at the moving boundary results in energy variation. Analytical solutions by the traveling wave method are compared with previous results using the perturbation method and Kotera's approach.