• 한국음향학회지
• /
• 제23권1호
• /
• pp.24-29
• /
• 2004

최근에 OAT(Ocean Acoustic Tomography) 분야에서 M-시퀀스를 이용한 펄스압축 (pulse compression) 기법을 이용하여 해양 구조를 분석하는 많은 연구가 이뤄지고 있다. M-시퀀스는 정합필터 (matched-filter)을 사용한 복조를 통해. 훌륭한 시간 분해능 (resolution) 및 도플러 분해능을 제공할 수 있다. 또한 수신 신호를 적절하게 처리함으로써 수신기 출력의 신호대잡음비 성능을 개선할 수 있으며, 수신 신호를 동기적으로 평균하는 것은 그것에 대한 좋은 예라고 할 수 있다. 그리고 데이터를 빠르고 효율적으로 처리할 수 있는 FHT (Fast Hadamard Transform) 또는 FFT (Fast Fourier Transform) 기법을 사용함으로써 처리 속도를 효율적으로 개선할 수 있다. 본 논문에서는 동해 연안에서 수집된 데이터를 이용하여 수중 음파의 다중경로 성분과 지연 시간을 분석하며, 송수신기간의 샘플링 속도 오차에서 비롯된 현상을 설명하고 오차를 보상하는 방법을 제시한다. 그리고 채널의 scattering 함수, 지연 전력 프로파일 (delay power profile), 시간 확산 특성 등을 통하여 해양 음향 채널의 특성을 분석하도록 한다.

• 한국측량학회지
• /
• 제16권1호
• /
• pp.17-26
• /
• 1998

본 논문은 Fast Hartley Transform 기법을 소개하고 이를 이용하여 한반도 주변의 지오이드를 결정하기 위한 것이다. 본 연구에서 사용한 중력 측정 데이터는 69,001점으로 남한지역과 BGI로부터 획득한 해상중력데이터로 구성하였으며, 북한쪽은 회기분석에 의하여 $1km\times{1km}$ 격자 간격으로 추정하였다. 지오이드의 결정을 위하여 96년에 발표된 EGM96 포텐셜모델을 채택하여 차수 360까지 계산하여 장 파장효과를 구하였고, FHT기법을 적용하여 중력데이터로부터 중 파장효과를 계산하여 이들 두 효과를 합하여 최종 지오이드면을 결정하였다. 본 연구를 통하여 얻어진 지오이드고를 GPS/Leveling에 의하여 구한 지오이드고와 비교한 결과 표준편차가 약 33 cm 이었다.

• 한국전문물리치료학회지
• /
• 제30권1호
• /
• pp.23-31
• /
• 2023

Background: Several factors contribute to shoulder pain, including abnormal neck posture, repeated use of the upper limbs, work involving raising the upper limbs above the head, and the effects of vibration. However, previous study has reported that constant vibration exposure could impact improvement of the stability on joints related with muscle recruitment and activation. For this difference reason, we need to verify for the complex study of relationship with repetitive upper limb movements, poor head posture, and constant vibration exposure. Objects: Our study was made to investigate the influence of vibration exposure on the shoulder muscle activity during forward-head and over-head tasks with isometric shoulder flexion. Methods: In a total of 22 healthy subjects, surface electromyography (EMG) data were collected from shoulder muscles (upper/lower trapezius, serratus anterior, and lumbar erector spinae) on tasks (neutral-head task [NHT], forward-head task [FHT], and over-head task [OHT]) with and without vibration exposure. Results: In all tasks, the EMG data of the upper trapezius and serratus anterior significantly increased with vibration exposure (p < 0.05). Furthermore, the EMG data of the lumbar erector spinae significantly increased with vibration exposure in the NHT and FHT (p < 0.05). Conclusion: We suggest that continuous vibration exposure during the use of hand-held tools in the tasks could be associated with harmful effects in the workplace. Lastly, we clinically need to examine the guidelines regarding the optimal posture and vibration exposure.

• 대한전기학회논문지
• /
• 제40권6호
• /
• pp.551-561
• /
• 1991

The probabilistic generation simulation plays a key role in power system expansion and operational planning especially for the calculation of expected energy, loss of load probaility and unserved energy expected. However, it is crucial to develop a probabilistic generation simulation algorithm which gives sufficiently precise results within a reasonable computation time. In a previous paper, we have proposed an efficent method using Fast Hartley Transform in convolution process for considering the thermal and nuclear units. In this paper, a method considering the scheduling of pumped-storage plants and hydro plants with energy constraint is proposed. The method also adopts FHT techniques. We improve the model to include multi-state and multi-block generation. The method has been applied for a real size model system.

• 기술사
• /
• 제20권1호
• /
• pp.14-20
• /
• 1987

고속아다마르변환은 Cooley-Tukey 알고리즘에 의해서 발표되어졌고, 그것은 메트릭스 분할 또는 계승의 기술에 의한 것이다. 본 보문은 단순한 기생메트릭스를 크로넥커 적에 의해 앞단과 연결시켜가면서 고속아다마르 변환을 보였다. 이것은 기존에 발표된 방법에 비해 쉽게 기생메트릭스를 구할 수 있는 것을 확인했고 수학적으로 완전함을 증명했다.

• 대한전자공학회논문지
• /
• 제26권10호
• /
• pp.1617-1623
• /
• 1989

The introduction of the fast Fourier transform(FFT),an efficient computational algorithm for the discrete Fourier transform(DFT) by Cooley and Tukey(1965), has brought to the limelight various other discrete transforms. Some of the analog functions from which these transforms have been derived date back to the early 1920's, for example, Walsh functions (Walsh, 1923) and Hadamard Transform(Enomoto et al, 1965). Fast algorithms developed for the forward transform are equally applicable, exept for minor changes, to the inverse transform. In this paper, we present a simple pipelined Hadamard matrix(HM) which is used to develop a fast algorithm for the Hadamard Processor (HP). The Fast Hadamard Transform(FHT) can be derived using matrix partitioning techniques. The HP system is incorporated through a modular design which permits tailoring to meet a wide range of video data link applications. Emphasis has been placed on a low cost, a low power design suitable for airbone system and video codec.

• Geomechanics and Engineering
• /
• 제22권6호
• /
• pp.475-488
• /
• 2020

The recent increase in the use of Expanded Polystyrene (EPS) geofoam in construction and geotechnical projects has driven researchers to investigate its behavior, more deeply. In this paper, a series of experimental tests to investigate the stress-strain behavior and the mechanical properties of EPS blocks, under monotonic axial loading are presented. Four different densities of cylindrically shaped EPS with different dimensions are used to investigate the effects of loading rate, height and diameter, as well as the influence of the density of EPS on the stress-strain response. The results show that increasing the height of the EPS samples leads to instability of the sample and consequent lower resistance to the applied pressure. Large EPS samples show higher Young's modulus and compressive resistance due to some boundary effects. An increase in the rate of loading can increase the elastic moduli and compressive resistance of the EPS geofoam samples, which also varies depending on the density of the samples. It was also determined that the elastic modulus of EPS increases with increasing EPS density. By implementing an efficient numerical procedure, the stress-strain response of EPS geofoam samples can be reproduced with great accuracy. The numerical analysis based on the proposed method can used to evaluate the effect of different factors on the behavior of EPS geofoam.

• Journal of Plant Biotechnology
• /
• 제36권4호
• /
• pp.415-422
• /
• 2009

This study aimed to develop carnation cultivars with new coloring system. We used four genes of Petunia hybrida - chalcone synthase (CHS), flavanone 3-hydroxylase (FHT), dihydroflavonol 4-reductase (DFR), and anthocyanidin synthase (ANS) - as probes, in order to isolate four genes from carnations (Dianthus Caryophyllus). The isolated genes were used as probes in order to select mutants out of collected carnations, using Northern blot analysis. The Northern blot analysis revealed 10 DFR mutants - Gumbyul, Eunbyul, Ballatyne, Crystal, Eugenia, Koreno, Imp. White Sim, West Crystal, White Alpine, and White Charotte. Six among the selected 10 cultivarswere excluded from the target cultivars, because Eugenia, Imp. White Sim, and White Alpine were proved to be double mutants of DFR and ANS, Koreno was considered to be a double mutant of DFR and CHS, and Gumbyul and Ballatyne were proved to be double mutants of DFR and CHI (Chalcone isomerase). Consequently, we selected five DFR mutants, including Virginie, which was already selected as a DFR mutant. Finally, we measured DFR activities in order to confirm the selection, and the results showed that all of the five cultivars - Eunbyul, Crystal, West Crystal, White Charotte, and Virginie - had got no DFR activity.