• Geophysics and Geophysical Exploration
• /
• v.11 no.4
• /
• pp.286-301
• /
• 2008

When magnetotelluric (MT) data are obtained in vicinity of the coast, the sea can distort observed MT responses, especially those of deep part of subsurface. We introduce an iterative method to correct the sea effect, based on the previous topographic correction method which removes the distortions due to topographic changes in seafloor MT data. The method first corrects the sea effect in observed MT impedance, and then inverts corrected responses in a model space without the sea. Due to mutual coupling between sea and subsurface structure, the correction and inversion steps are iterated until changes in each result become negligible. The method is validated for 1-D and 2-D structure using synthetic MT data produced by 3-D forward modeling including surrounding seas. In all cases, the method closely recovers the given structure after a few iterations. To test the applicability of the proposed method to field data, we generate synthetic MT data for the Jeju Island whose 1-D conductivity structure is well known, using 3-D forward modeling. The distortions due to the surrounding sea start to appear below the frequency about 1 Hz, and are relatively severe in the electrical field perpendicular to the coastline because of the location of the observation sites. The proposed method successfully eliminates the sea effect after three iterations, and both 1-D and 2-D inversion of corrected responses closely recover the given subsurface structure of the Jeju Island model.

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

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.26 no.6B
• /
• pp.794-801
• /
• 2001

본 논문에서는 rank-order 필터의 구현을 위해 세 가지 신경회로망의 구조를 제시하고 분석하며 용도를 제안한다. 첫 번째 신경회로망을 이용하여 2-입력 정렬기를 제안하고 이를 이용하여 계층적인 N-입력 정렬기를 구성한다. 두 번째로 입력 신호간의 상대적인 크기 정보를 이용하여 학습 패턴을 구성한 후 역전파 학습 기법을 이용하여 구현되는 순방향 신경회로망을 이용한 rank-order 필터를 구현한다. 세 번째로 신경회로망의 구조의 출력층에 외부 입력으로 순위 정보를 가지도록 하는 rank-order 필터를 순방향 신경회로망을 이용하여 구현한다. 그리고 이러한 제안된 기술들에 대해 확장성, 구조의 복잡도와 시간 지연 등에서의 성능을 비교, 평가한다. 2-입력 정렬기를 이용하는 방식은 확장이 용이하고 비교적 구조가 간단하나 입력 신호들의 정렬을 위해 신경회로망은 순환하는 구조를 가지며 입력 신호의 수에 비례하는 반복 연산 후에 결과를 얻게 된다. 반면에, 순방향 신경회로망을 이용한 rank-order 필터의 구현 방식은 이러한 반복 연산으로 인한 시간 지연을 줄일 수 있으나 상대적으로 복잡한 구조를 가진다.

• Journal of the Earthquake Engineering Society of Korea
• /
• v.1 no.1
• /
• pp.1-10
• /
• 1997

Current seismic design philosophy for reinforced concrete (RC) structures on energy dissipation through large inelastic defomations. A nonlinear dynamic analysis which is used to represent this behavior is time consuming and expensive, particularly if the computations have to be repeated many times. Therefore, the selection of an efficient yet accurate alogorithm becomes important. The main objective of the present study is to propose a new technique herein called the prediction approach with siffness measure (PASM) method in the convetional direct integration methods, the triangular decomposition of matrix is required for solving equations of motion in every time step or every iteration. The PASM method uses a limited number of predetermined decomposed effective matrices obtained from stiffness states of the structure when it is deformed into the nonlinear range by statically applied cyclic loading. The method to be developed herein will reduce the overall numerical effort when compared to approaches which recompute the stiffness in each time step or iteration.

• Journal of the Institute of Electronics and Information Engineers
• /
• v.50 no.7
• /
• pp.140-148
• /
• 2013

This paper presents a iterative Bose-Chaudhuri-hocquenghem (i-BCH) code and its high-speed decoder architecture for 100 Gb/s optical communications. The proposed architecture features a very high data processing rate as well as excellent error correction capability. The proposed 6-iteration i-BCH code structure with interleaving method allows the decoder to achieve 9.34 dB net coding gain performance at $10^{-15}$ decoder output bit error rate to compensate for serious transmission quality degradation. The proposed high-speed i-BCH decoder architecture is synthesized using a 90-nm CMOS technology. It can operate at a clock frequency of 430 MHz and achieve a data processing rate of 100 Gb/s. Thus, it has potential applications in next generation forward error correction (FEC) schemes for 100 Gb/s optical communications.

• Journal of the Korea Concrete Institute
• /
• v.18 no.6 s.96
• /
• pp.729-736
• /
• 2006

It has been shown that many Reinforced Concrete(RC) structures designed without seismic details have experienced brittle shear failures in the beam-column joint area and resulted in large permanent deformations and structural collapse. In this study, experimental investigations into the performance of exterior reinforced concrete beam-column joints strengthened with the carbon fiber-reinforced polymer(CFRP) under cyclic loading were presented. The CFRP has been applied by choosing different combinations and locations to determine the effective way to improve structural performances of joints. Eight beam-column joints were tested to investigate behaviors of each specimen under cyclic load and to compare performances of seismic retrofit. According to the experimental study, the retrofit strengthened with the CFRP provides significant improvements of flexural capacity and ductility of beam-column joints originally built without seismic details.

• Journal of the Korean Society for Nondestructive Testing
• /
• v.36 no.3
• /
• pp.225-230
• /
• 2016

Fiber Bragg grating (FBG) sensors are currently the most prevalent sensors because of their unique advantages such as ease of multiplexing and capability of performing absolute measurements. They are applied to various structures for structural health monitoring (SHM). The signal characteristics of FBG sensors under thermal loading should be investigated to enhance the reliability of these sensors, because they are exposed to certain cyclic thermal loads due to temperature changes resulting from change of seasons, when they are applied to structures for SHM. In this study, tests on specimens are conducted in a thermal chamber with temperature changes from -$20^{\circ}C$ to $60^{\circ}C$ for 300 cycles. For the specimens, two types of base materials and adhesives that are normally used in the manufacture of packaged FBG sensors are selected. From the test results, it is confirmed that the FBG sensors undergo some degree of compressive strain under cyclic thermal load; this can lead to measurement errors. Hence, a pre-calibration is necessary before applying these sensors to structures for long-term SHM.

• Journal of the Earthquake Engineering Society of Korea
• /
• v.5 no.3
• /
• pp.37-43
• /
• 2001

The energy concept has been extended to compare the hysteretic performance between various structural systems. As a result, the energy absorption efficiency is defined as the cumulative energy absorption capacity of a structural system normalized by that of the elasto-perfectly plastic system as a benchmark for comparisons. For this, the construction of energy curves from the experimental results obtained by cyclic loading tests is required. Using the proposed procedure, structures differing from each other in geometry, material and construction can be relatively and objectively compared for seismic performance. Also the beauty of this method is in its irrelevance to the structural failure mode. The proposed procedure was validated by application to the experimental results of two different specimens.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.25 no.2
• /
• pp.66-73
• /
• 2021

In the existing study of steel beams with openings, openings are located at a location where the distance to the support point is equal to or greater than the section height. Considering the facilities using the openings in the steel beam, the distance from the opening to the support point may be closer than the height of the beam section. Therefore, research on this is needed. This study is an experimental study to understand the structural performance of beams with openings close to the ends subjected to Cyclic Loading. In addition, in this study, we want to understand the structural performance through experiments on beams with openings reinforced with vertical or horizontal steel plates.

• Proceedings of the Korean Society of Broadcast Engineers Conference
• /
• 2016.06a
• /
• pp.297-299
• /
• 2016

본 논문에서는 ATSC 3.0 규격에서 정의되는 부트스트랩 신호를 이용한 수신기 동기 방식에 대해서 소개한다. ATSC 3.0 방송 신호의 프레임에 앞서서 전송되는 부트스트랩 신호는 시간영역에서 반복되는 구조를 가지므로 이를 이용하여 수신기에서 타이밍 및 주파수 동기를 획득할 수 있다. 본 논문에서는 부트스트랩 신호의 시간영역의 반복구조를 이용하여 수신기에서 타이밍 및 주파수 동기 획득 방법을 제시한다.