• 정보처리학회논문지D
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• 제18D권5호
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• pp.323-328
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• 2011

정확한 내용 기반 이미지 검색을 위하여 Earth mover's distance와 Optimal color composition distance와 같은 거리함수들이 제안되었다. 이 거리함수들은 정확도가 높은 검색 결과를 가져오지만 검색 시간이 매우 크기 때문에 대용량 데이터베이스에서 사용하기 어렵다는 문제점을 가지고 있다. 본 논문에서는 이러한 문제를 해결하기 위하여 선형 시간에 근사 Earth mover's distance를 구하기 위한 새로운 거리 함수를 제안한다. 제안하는 방법은 선형 시간에 두 이미지의 거리를 계산하기 위하여 공간 채움 곡선을 이용한다. 다양한 실험을 통하여 본 논문에서 제안하는 방법의 우수성을 검증한다. 실험 결과, 제안하는 기법이 Earth mover's distance에 비해 약 160배 정도의 검색 속도 향상 효과를 보이면서도 매우 유사한 결과를 검색하는 것으로 나타났다.

• 한국터널지하공간학회 논문집
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• 제10권2호
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• pp.139-152
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• 2008

본 연구에서는 TBM 디스크 커터의 암석절삭에 관하여 기존의 LCM시험을 모사하기 위한 수치해석을 실시하였다. 수치모사를 위하여 3차원 동적 파괴해석이 가능한 상용 프로그램인 AUTODYN-3D를 선정하였으며, 이를 통하여 각기 다른 4가지 이상의 커터간격 조건에 대해 수치해석을 수행하였다. 상기 프로그램 상에서 디스크 커터와 암석 시편을 3차원 형상으로 모델링 한 후, 8개 암종에 대해서 수치적 절삭시험을 진행하였다. 그 결과, 수치해석과 LCM시험에서 도출된 최적 커터간격은 대체로 일치하여, 추후 LCM시험결과를 보완할 수 있을 것으로 판단되었다. 그러나 등방성 암석에는 적용성이 매우 높았던 반면, 절리가 존재하거나 이방성을 가지는 암석의 경우에는 LCM시험결과와 비교하여 비에너지가 다소 크게 산출되었다. 따라서 이방성 암석의 모델링에 대한 추가적인 연구가 수반되어야 할 것으로 판단된다.

• 대한치과교정학회지
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• 제49권2호
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• pp.81-88
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• 2019

Objective: The aim was to assess the intraobserver and interobserver reliabilities of temporomandibular joint linear measurements and condylar shape classifications performed with cone-beam computed tomography (CBCT). Methods: CBCT images of 30 patients were measured at two different time points by two orthodontists using the Dolphin 3D program (n = 60). Anterior, posterior, and superior joint space measurements and sagittal joint morphology classification in the sagittal view and medial and lateral joint space and mediolateral width measurements and coronal joint morphology classification in the coronal view were recorded. Intraclass-interclass correlation coefficients (ICC) and kappa statistics were used to assess intraobserver and interobserver reliability for the measurements and morphology classifications, respectively. Results: The ICC values were good for measurements of the posterior joint space by observer I and for measurements of the posterior, medial, and lateral joint spaces by observer II, while the other intraobserver measurements were excellent. Only the mediolateral width measurements showed excellent interobserver ICC values, while the other measurements showed good interobserver ICC values. Intraobserver agreement for the sagittal morphology classifications was moderate (${\kappa}=0.479$) and almost perfect (${\kappa}=0.858$) for observers I and II, respectively, while the corresponding agreement for the coronal morphology classifications was substantial for both observers. The interobserver agreement values for sagittal and coronal morphology classifications were slight (${\kappa}=0.181$) and fair (${\kappa}=0.265$), respectively. Conclusions: Linear temporomandibular joint measurements were reproducible and reliable in both intraobserver and interobserver evaluations. However, interobserver agreement for assessments of condylar shape was low.

• 영어영문학
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• 제57권6호
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• pp.939-958
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• 2011

Ezra Pound has an idea of poetry as a field of energy in which words interact with each other with kinetic energy. The energy field which Pound creates in his poem is analogous to the theory of electromagnetism developed by Michael Faraday and James Maxwell, who look upon the space around magnets, electric charges and currents not as empty but as filled with energy and activity. Pound argues that "words are charged with force like electricity," demonstrating that words charged with their own images or energies of positive or negative valence interact one another. This idea is similar to Faraday's concept of "line of force" which he used to represent the disposition of electric and magnetic forces in space. Pound's concept of "image" as an "intellectual and emotional complex in an instant" is remarkably consonant with the confluence of electric and magnetic fields that are coupled to each other as they travel through space in the form of electromagnetic waves. The instant profusion of conception and perception, much like that of electric and magnetic fields, enables Pound to move beyond the sequential and linear hierarchy in time and space. Particularly, Maxwell's stunning discovery that the electromagnetic waves propagate in space at 'the speed of light' has allowed Pound a relativistic sense of escape from the limitations of Newtonian absolute time and space. Pound's poetry transcends any geographical space and sequential time by rendering and juxtaposing images simultaneously. Pound was fully aware of light and electricity fundamental to what he called his world "the electric world." Pound's experiments in Imagism and Vorticism can be considered an attempt to rediscover a place for poetry in the modern world of science and technology. Almost all the appliances that we think of today as modern were laid down in the closing decades of the 19th century and the first decades of the 20th century, in response to the availability of electromagnetic energy. This paper explores how Pound responded to the age of modern technology and science, examining his conception of "image" through his many analogies and similes drawn from electromagnetism. Pound's imagist poetics and poetry come to embody, not only the characteristics of the electric age in the early twentieth century, but the principles of electromagnetism the electric age is based upon.

• ETRI Journal
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• 제40권2호
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• pp.218-226
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• 2018

Multiuser detection (MUD) and channel estimation techniques in space-division multiple-access aided orthogonal frequency-division multiplexing systems recently has received intensive interest in receiver design technologies. The maximum likelihood (ML) MUD that provides optimal performance has the cost of a dramatically increased computational complexity. The minimum mean-squared error (MMSE) MUD exhibits poor performance, although it achieves lower computational complexity. With almost the same complexity, an MMSE with successive interference cancellation (SIC) scheme achieves a better bit error rate performance than a linear MMSE multiuser detector. In this paper, hybrid ML-MMSE with SIC adaptive multiuser detection based on the joint channel estimation method is suggested for signal detection. The simulation results show that the proposed method achieves good performance close to the optimal ML performance at low SNR values and a low computational complexity at high SNR values.

• 호남수학학술지
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• 제33권1호
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• pp.73-84
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• 2011

Let f, g, h, k : $\mathbb{R}^n{\rightarrow}\mathbb{C}$ be locally integrable functions. We deal with the $L^{\infty}$-version of the Hyers-Ulam stability of the quadratic functional inequality and the Pexiderized quadratic functional inequality $${\parallel}f(x + y) + f(x - y) -2f(x) - 2f(y){\parallel}_{L^{\infty}(\mathbb{R}^n)}\leq\varepsilon$$ $${\parallel}f(x + y) + g(x - y) -2h(x) - 2f(y){\parallel}_{L^{\infty}(\mathbb{R}^n)}\leq\varepsilon$$ based on the concept of linear functionals on the space of smooth functions with compact support.

• 터널과지하공간
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• 제6권2호
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• pp.175-183
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• 1996

Linear cutting tests on granite were conducted to evaluated the cutting performance of abrasive water jet(AWJ) using several types of abrasives. The abrasives used in the tests were grarnet, alumimum oxide, and silicon carbide. And one type of granite which is comercially known as "KeuchangSuk" was used as workpiece throughout the tests. The results from the tests were described in terms of cutting depth and abrasive productivity. Authors tried to confirm the effects of the operational parameters of abrasive mass flow rate, water pressure, and traverse speed of nozzle on cutting depth and presented almost all the data obtained in the tests. Abrasive productivity can be defined as the area of kerf wall cut by unit weight of abrasive and is an important factor to evaluated the cutting ability of abrasive and assess the cost effectiveness of an AWJ system. In the tests the maximum abrasive productivities of garnet, alumina, and silicon carbide were about 0.21, 0.24, and 0.20 $\textrm{cm}^2$ respectively under similar operational conditions.onditions.

• Wind and Structures
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• 제14권2호
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• pp.133-151
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• 2011

For a detailed investigation of the dynamic behaviour of slender bridges under wind action especially the motion-induced fluid forces should be available not only for harmonic motions but also for more general ones. If linear transfer behaviour is assumed, the force-displacement relation for almost arbitrary motions can be handled in the frequency domain using aerodynamic transfer functions. In aerospace engineering as well as in bridge engineering, these functions are usually approximated by special kinds of complex-valued rational functions which depend on complex frequencies. The quality of this approximation is evaluated for several bridge cross sections in this article. It is shown that rational functions are for some sections scarcely suitable to realistically represent the transfer behaviour of motion-induced aerodynamic forces for arbitrarily complex frequencies.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1986년도 한국자동제어학술회의논문집; 한국과학기술대학, 충남; 17-18 Oct. 1986
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• pp.238-243
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• 1986

Distillation columns are widely used in almost every chemical plant. The use of multivariable control for such units is attractive because of the strong interactions exhibited between outputs and inputs and the desire to control simultaneously both top and bottom products. In this research design of a robust multivariable controller for distillation column was considered; output feedback controller with proportional and integral modes was designed using pole assignment. The transfer function matrix was obtained by fitting the step response realtions between single input double output pairs of variables. This matrix was then converted to linear time invariant state space model by multivariable realization technique. With the proposed multivariable proportional and integral controller applied to the process, the result of the digital computer simulation showed a good performance of asymtotic tracking. The limited experimental performance of this multivariable control was compared with the result from simulation. It was found that the proposed controller performed satisfactorily for the distillation column which separated binary mixture of methanol and water.

• 대한수학회보
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• 제44권4호
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• pp.731-742
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• 2007

Let X be a Banach space, $A:D(A){\subset}X{\rightarrow}X$ the generator of a compact $C_0-semigroup\;S(t):X{\rightarrow}X,\;t{\geq}0$, D a locally closed subset in X, and $f:(a,b){\times}C([-q,0];X){\rightarrow}X$ a function of Caratheodory type. The main result of this paper is that a necessary and sufficient condition in order that D be a viable domain of the semi linear differential equation of retarded type $$u#(t)=Au(t)+f(t,u_t),\;t{\in}[t_0,\;t_0+T],{u_t}_0={\phi}{\in}C([-q,0];X)$$ is the tangency condition $$\limits_{h{\downarrow}0}^{lim\;inf\;h^{-1}d(S(h)v(0)+hf(t,v);D)=0}$$ for almost every $t{\in}(a,b)$ and every $v{\in}C([-q,0];X)\;with\;v(0){\in}D$.