• 한국자동차공학회논문집
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• 제4권5호
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• pp.26-36
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• 1996

The fully developed turbulent momentum and heat transfer induced by the square-ribbed roughness elements on both the inner and outer wall surfaces in concentric annuli are studied analytically based on a modified turbulence model. The analytical results of the fuid flow are verified by experiment. The experiment is done with a pitot tube and a X-type hot wire anemometer to measure the time mean velocity profiles, zero shear stress positions, maximum velocity positions and friction factors, and etc. shown in Fig.1. The resulting momentum and heat transfer are discussed in terms of various parameters, such as the radius ratio, the relative roughness, the roughness density, Reynolds number, Nusselt bumber and Prand시 number. The study demonstrates that certain artificial roughness elements may be used to enhance heat transfer rates with advantage from the overall efficiency point of view by investigating turbulent flows and heat transfer in Fig.1.

• 대한음성학회지:말소리
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• 제68권
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• pp.95-114
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• 2008

The recent growing popularity of statistical methods in machine translation requires much more large parallel corpora. A Korean-English parallel corpus, however, is not yet enoughly available, little research on this subject is being conducted. In this paper we present a hybrid method of aligning sentences for Korean-English parallel corpora. We use bilingual news wire web pages, reading comprehension materials for English learners, computer-related technical documents and help files of localized software for building a Korean-English parallel corpus. Our hybrid method combines sentence-length based and word-correspondence based methods. We show the results of experimentation and evaluate them. Alignment results from using a full translation model are very encouraging, especially when we apply alignment results to an SMT system: 0.66% for BLEU score and 9.94% for NIST score improvement compared to the previous method.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2005년도 춘계학술대회 논문집
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• pp.207-210
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• 2005

In this paper, a two-dimensional cross-channel model was applied to investigate influence of the gas diffusion layer(GDL) property and flow field geometry in the anode side for proton exchange membrane fuel cell(PEMFC). The GDL is made of a porous material such as carbon cloth, carbon paper, or metal wire mesh. To the simplicity, the GDL is represented as a block of material containing numerous pathways through which gaseous reactants and liquid water can pass. The purpose of present work was to study the effect of the GDL thickness and the porosity, and flow field geometry by computational fluid dynamics(CFD)

• 제어로봇시스템학회논문지
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• 제8권4호
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• pp.288-291
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• 2002

We characterize multipath fading channel dynamics at the packet level and analyze the corresponding data queueing performance in various environments. We identify the similarity between wire-line queueing analysis and wireless network per-formance analysis. The second order channel statistics, i.e. channel power spectrum, is fecund to play an important role in the modeling of multipath fading channels. However, it is identified that the first order statistics, i.e. channel CDF also has significant impact on queueing performance. We use a special Markov chain, so-called CMPP, throughout this paper.

• 한국정밀공학회지
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• 제22권1호
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• pp.160-166
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• 2005

In this paper, the combined system equation of motion, which can analyze the dynamic interaction between pantograph and catenary system, is derived by adopting absolute nodal coordinates and rigid body coordinates. The analysis results are compared with real experiment data from test running of Korean high-speed train (HSR 350x). In addition, a computation method for the dynamic stress of contact wire is presented using the derived system equation of motion. This method might be good example and significant in that the structural and multibody dynamics model can be unified into one numerical system.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1995년도 추계학술대회 논문집
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• pp.555-558
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• 1995

In designing the anti-sway controller for crane system in the industrial field, one of the basic problem is to keep the stability of system, even if the mathematical model of the plant is not exact and disturbance exists. Form this point of view, a two-degree-of-freedom(2DOF) servo controller effact to the system in which the integral compensation is effctive only when a modeling error and/or a disturbance input exist. In this paper, the change of load weight and variation of wire rope length considered as the structured uncertainty, and design the 2DOF servo contorller using independently the informations of reference signal and control output with both feedforward and feedback. The effectivenss is proved through the results for the anti-sway system in the system with the position control of trolley.

• 한국정밀공학회지
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• 제9권1호
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• pp.96-105
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• 1992

A study on the construction of a CAD/CAM system operated by 16 Bit PC basic language, for machining sculptured surface of die, was carried out. The system consists of 2 steps i.e., process for geometric modelling by wire frame and process for machining data generation. Geometric modelling for sculptured surface is made by the point data fitting, parallel sweeping, normal sweeping and linear connection of cross section curve. Machining data are gained by cutter off-set of geometric model data and machining carried out by DNC. This system is to be proved enough for rough cutting by actual machining experiment. But, for becoming a high level system, another method of cutter off-set has to be regarded and system must be reconstructed by another program language.

• 소음진동
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• 제8권2호
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• pp.346-352
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• 1998

This paper presents actuating characteristics of an asymmetric high-speed optical pick-up fine actuator that can be installed in a small area such as a notebook personal computer. In the asymmetric actuator four points (mass center, actuation center, supporting point of wire suspension on a bobbin, and optical axis) are not coincident so that the proposed actuator suspension reveals undesirable suspension resonance in the pitch and yaw direction. Lumped parameter dynamic model in each direction is used to investigate the driving characteristics with respect to relative location of the four points. Some of desired design directions toward reducing resonance peaks are suggested by using sensitivity information. In order to avoid undesirable resonance, at least supporting point on the obbin must be located in the middle of the mass and actuation center of the asymmetric pick-up actuator.

• 무역상무연구
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• 제15권
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• pp.59-87
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• 2001

In recent years electronic fund transfers covered by the Electronic Fund Transfer Act 1978 for consumer protection and the Article 4A of Uniform Commercial Code(U.C.C.) 1989 for wholesale electronic payments in United States. Electronic fund transfers carried out by use of a wire transfer network, automated clearing house, or other communication system of a clearing house or other association of banks such as direct deposit, Fedwire, automated teller machine, point-of-sale, and credit card transactions have been increasingly common in consumer transactions and wholesale transactions. Especially, the Article 4A of U.C.C. governs the rights and obligations associated with transactions such as an issue and acceptance of payment order, execution of sender's payment order by receiving bank, and payment. These legal frameworks in connection with electronic fund transfers in United States can play a leading role in establishing model not only within the United States, but also as a basis for developments of electronic commerce law in Korea including other countries.

• Structural Engineering and Mechanics
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• 제2권1호
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• pp.63-80
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• 1994

A cable is considered as a system of helical wires and a core with distributed dry friction forces at their interfaces. Deformations of the cable subjected to a uniform bending are analyzed. It is shown that there is a critical bending curvature when a slip at the wire-core interface occurs. It originates at the neutral axis of the cross section of the cable and then spreads symmetrically over the cross section with the increase of bending. The effect of slippage on the cable stiffness is investigated. This model is also used to analyze a cable under the quasi-static cyclic bending. Explicit expression for the hysteretic losses per cycle of bending is derived. Numerical examples are given to show the influence of dry friction and helix angle on the bending stiffness and hysteretic losses in the cable.