• 한국생산제조학회지
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• 제21권2호
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• pp.208-213
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• 2012

In this paper, the radial error of a rotary table at five-axis machine tool is evaluated by utilizing ISO 230-2 and estimation method using double ball-bar. The geometric error of a rotary table is defined as position dependent geometric errors or position independent geometric errors according to their physical character. Then estimation method of geometric errors using double ball-bar is simply summarized including measurement path, parametric modeling and least squares approach. To estimate representative radial error, offset error, set-up error which affect to the double ball-bar data, mean value of measured data including CCW/CW-direction are used at estimation process. Radial errors are separated from measured data and used for evaluation with ISO 230-2. Finally, suggested evaluation method is applied to a rotary table at five-axis machine tool and its result is analyzed to improve the accuracy of the rotary table.

• 한국지구물리탐사학회:학술대회논문집
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• 한국지구물리탐사학회 2004년도 대한지구물리학회.한국지구물리탐사학회 공동학술대회 초록집
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• pp.232-237
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• 2004

Anatahan Volcano in the Commonwealth of the Northern Mariana Islands (CNMI) erupted for the first time in recorded history on 10 May 2003. The underwater acoustic records of earthquakes, explosions, and tremor produced during the eruption were recorded on a sound-channel hydrophone deployed in February 2003. Acoustic propagation models show the seismic to acoustic conversion at Anatahan is particularly efficient, aided by the slope of the seamount toward the hydrophone. The hydrophone records confirm the onset of earthquake activity at 01:53Z on 10 May, as well as the onset (at ${\~}$06:20Z) of continuous, low-frequency (5-40 Hz) acoustic energy that is likely volcanic tremor related to magma intrusion. The hydrophone recorded a total of 458 earthquakes associated with the eruption. To predict the character of acoustic signals generated from Anatahan, we developed a moment-tensor representation of a volcano-seismic source that is governed by the geometry of the source and the physical properties of the magma. A buried magmatic pipe model was adopted, and numerically modeling source parameters such as the pipe radius and magma viscosity enable us to grasp the inward nature of Anatahan Volcano.

• 패션비즈니스
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• 제22권4호
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• pp.93-105
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• 2018

Using FDM 3D printing, yarn shape and composition were modeled and 3D printed with PLA and TPU filaments currently used for apparel. Based on this, mechanical characteristics were measured to determine 3D printing yarn according to type of filaments in the 3D printed output and deformation and recovery characteristics due to differences in structure type. As a result of examining tensile and shear characteristics of PLA and TPU 3D printing compiles, TPU overall was measured with significantly lower stress than PLA. This is due to high elasticity of TPU's character, revealing that it has better flexibility than PLA. In addition, during deformation due to external forces, the more freedom between the head and foot parts of the loop, and the lower the force associated with each other, the more flexible it is. TPU revealed that it was easier to tension and recovery from tensile deformation than PLA, indicating potential for clothing materials using 3D printing. If high-molecular materials, such as PLA flexibility, it is likely to provide some flexibility through development of styles, including degree of freedom in modeling. Based on this, we provide basic data for developing 3D printing textures that can be satisfied with textile for apparel.

• 한국컴퓨터정보학회논문지
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• 제7권4호
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• pp.108-114
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• 2002

국어의 로마자 표기법 기본원칙을 모르더라도 웹 상에서 한글단어, 문장, 문서를 문자열(String)로 입력받아 국어의 로마자 표기 자동변환이 가능하게 설계 및 구현하였다. 특히, 표음 중심의 전사(Transcription) 표기법의 기계적 변환을 위해 알고리즘(algorithm)화된 음운법칙을 적용하여 소리글자로 자동 변환 후 정부 표준안인 국어 로마자 표기법 테이블에서 대응 글자를 참조하여 기계화 코드 변환이 가능토록 자동변환 알고리즘 설계하였으며, 유니코드(Unicode)와 아스키(ASCII)테이블에서 잘 쓰이지 않는 코드를 반달표(ˇ)와 어깻점(')등 특수부호로 할당하여 글꼴을 제작하였다. 또한 예외어 사전관리를 통한 예외 처리 문제에 대한 해결 방안을 제시하였으며, UML표기와 C++ 언어를 이용하여 사용자 편리성과 구현에 대한 모델을 제안하였다.

• Bulletin of the Korean Chemical Society
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• 제28권7호
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• pp.1141-1150
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• 2007

Molecular modeling study has been performed to assist in the design of PTP1B inhibitors using FlexX. FlexX dockings with 19 test ligands, whose structures have been determined by X-ray crystallography, were successful in reproducing the experimental conformations within the protein. An increase in biological activity is observed as hydrophobic character of formylchromone derivatives increases. Most ligands bind to the activesite regions of the protein successfully in two different score runs. The Drug score run gave better results than the FlexX score run based on the score, rank, binding modes and bond distance of docked structures. Consensus values from the CScore scoring function are between 3 and 5, suggesting that the scoring scheme is reliable. All formylchromone inhibitors considered in this work show unidirectional binding modes in the active site pocket, which is contrary to the bidirectional X-ray results by Malamas et al. and amino acid residues responsible for such orientation are identified to help further development of the inhibitors.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 하계학술대회 논문집 F
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• pp.2610-2612
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• 1999

In controlling vector of induction motor, PID controller is required much time as the expert should control manually a gain of controller according to plant or a change of circumstances. Accordingly, this paper has gotten a gain of PID controller used neural network by self-funning method in order to settle above problem. The neural network can describe an input/output features in spite of non-linear system which is hard to get mathematical model by controlling the strength of connection by learning. It has a strong character against a distortion and noise of input information, and is suitable modeling of diver-variable system which is composed of several input/output. This paper has represented the self-tunning method for gain of PID controller used neural network when using PID controller to control speed of induction motor, and has checked strong characters against distortion and noise of input information through simulation.

• ETRI Journal
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• 제39권2호
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• pp.234-244
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• 2017

Research interest in three-dimensional multiple-input multiple-output (3D-MIMO) beamforming has rapidly increased on account of its potential to support high data rates through an array of strategies, including sector or user-specific elevation beamforming and cell-splitting. To evaluate the full performance benefits of 3D and full-dimensional (FD) MIMO beamforming, the 3D character of the real MIMO channel must be modeled with consideration of both the azimuth and elevation domain. Most existing works on the 2D spatial channel model (2D-SCM) assume a wide range for the distribution of elevation angles of departure (eAoDs), which is not practical according to field measurements. In this paper, an optimal FD-MIMO planar array configuration is presented for different practical channel conditions by restricting the eAoDs to a finite range. Using a dynamic network level simulator that employs a complete 3D SCM, we analyze the relationship between the angular spread and sum throughput. In addition, we present an analysis on the optimal antenna configurations for the channels under consideration.

• 대한기계학회논문집A
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• 제24권3호
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• pp.634-644
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• 2000

Fatigue crack growth and life is estimated by various fracture mechanical parameters but affected by load, material and environment. Fatigue character of component without surface notch cannot be e valuated by above-mentioned parameters due to microstructure of in-service material. Single fracture mechanical parameter or nondestructive parameter cannot predict fatigue damage in arbitrary boundary condition but multiple fracture mechanical parameters or nondestructive parameters can Fatigue crack growth modelling with three point representation scheme uses this merit but has limit on real-time monitoring. Therefore, this study shows fatigue damage model using backpropagatior. neural networks on the basis of X-ray half breadth ratio B/$B_o$ fractal dimension $D_f$ and fracture mechanical parameters can predict fatigue crack growth rate da/dN and cycle ratioN/$N_f$ at the same time within engineering estimated mean error(5%).

• The Journal of the Acoustical Society of Korea
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• 제24권3E호
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• pp.87-89
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• 2005

The acoustical sources of intake and exhaust systems in fluid machines are often characterized by the source impedance and strength using linear frequency-domain modeling. In the case of the sources which are nonlinear and time-variant, however, the source parameters were sometimes incorrectly obtained. In this paper, the source model and direct measurement technique are modified in order to evaluate the effect due to nonlinear and periodically time-varying source character as well as the linear property of the reflectivity of in-duct fluid machine source. With a priori known kinematical information of the source, the types of nonlinear time-variant terms can be presumed by a simple physical model, in which there is practically no restriction on the form of the model. The concept of source impedance can be extendable by introducing the linear frequency response function for each nonlinear or time-variant input. Extending the conventional method and adapting the reverse MISO technique, it is possible to develop a direct method that can deal with the nonlinear time-variant source parameters. The proposed direct method has a novel feature that there is no restriction on the probability or spectral natures of the excited sound pressure data. The present method is verified by the simulated measurements for simplified fluid machines. It is thought that the proposed method would be useful in predicting the insertion loss or the radiated sound level from intake or exhaust systems.

• 한국방재학회지
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• 제2권4호
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• pp.40-47
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• 2002

Since it is important to understand the bio-climatic change in Seoul for ecological city planning in the future, this paper gives an overview on bio-climate analysis of urban environments at Seoul. We analyzed its characteristics in recent years using the observations of 24 of Automatic Weather Station (AWS) by Korea Meteorological Administration (KMA). In urbanization, Seoul metropolitan area is densely populated and is concentrated with high buildings. This urban activity changes land covering, which modifies the local circulation of radiation, heat and moisture, precipitation and creating a specific climate. Urban climate is evidently manifested in the phenomena of the increase of the air temperature, called urban heat Island and in addition urban sqall line of heavy rain. Since a city has its different land cover and street structure, these form their own climate character such as climate comfort zone. The thermal fold in urban area such as the heat island is produced by the change of land use and the air pollution that provide the bio-climate change of urban eco-system. The urban wind flow is the most important climate element on dispersion of air pollution, thermal effects and heavy shower. Numerical modeling indicates that the bio-climatic transition of wind wake in urban area and the dispersion of the air pollution by the simulations of the wind variation depend on the urban land cover change. The winds are separately simulated on small and micro-scale at Seoul with two kinds of kinetic model, Witrak and MUKLIMO.