• Nuclear Engineering and Technology
• /
• v.36 no.3
• /
• pp.219-228
• /
• 2004

[1] and [2] present an approach to diagnosing possible defects in the mechanical systems of a nuclear power plant. In this paper, by using a fault library as a database and training data, we develop a diagnostic algorithm 1) to decide whether an Air Operated Valve system is sound or not and 2) to identify the defect from which an Air-Operated Valve system suffers, if any. This algorithm is composed of three stages: a neural net stage, a non-neural net stage, and an integration stage. The neural net stage is a simple perceptron, a pattern-recognition module, using a neural net. The non-neural net stage is a simple pattern-matching algorithm, which translates the degree of matching into a corresponding number. The integration stage collects each output and makes a decision. We present a simulation result and confirm that the developed algorithm works accurately, if the input matches one in the database.

• Proceedings of the KSR Conference
• /
• 1999.05a
• /
• pp.238-247
• /
• 1999

A study on the static type simulator will include an instructor's station, two cabs for ISA with visual and sound system, and realistic and accurate model of the trains operation. The simulator is easy to extend and maintenance using structured the S/W. The training of new drives requires that the environment of the cab, controls placement, etc. must highly realistic so that driver can readily transfer his training experience to the real world. The simulator detailed software model and extensive scenario design capability allows both for a wide variety of scenarios and accurately modeled response covering most aspects of brakes, rules, and faults.

• Proceedings of the Computational Structural Engineering Institute Conference
• /
• 2001.10a
• /
• pp.261-268
• /
• 2001

Highway bridges are important infrastructures for national transportation systems. However, due to overweight trucks frequently moving on highways, highway structures have been gradually damaged and economical loss has grown severe. To maintain a highway bridge safe and sound, properties and loading characteristics of passing trucks on the bridge must be evaluated WIM(Weigh-In-Motion) systems have been developed by many research groups for multiple purposes. Most of the developed WIM systems have applied moment influence lines to identify loading characteristics. Since passing trucks are dynamic loads, however, the identified loads by the influence lines for static loads cannot represent the actual situation correctly. The current research investigates the effects of problem of different loading characteristics on load identification and proposes a new algorithm using the concept of moment influence surface. A numerical simulation study is carried out.

• Journal of Mechanical Science and Technology
• /
• v.19 no.8
• /
• pp.1611-1620
• /
• 2005

This paper shows the use of wavelet transformation combined with inverse acoustics to reconstruct the surface velocity of a noise source. This approach uses the boundary element analysis based on the measured sound pressure at a set of field points, the Helmholtz integral equations and wavelet transformation for reconstructing the normal surface velocity field. The reconstructed field can be diverged due to the small measurement errors in the case of nearfield acoustic holography (NAH) using an inverse boundary element method. In order to avoid this instability in the inverse problem, the reconstruction process should include some form of regularization for enhancing the resolution of source images. The usual method of regularization has been the truncation of wave vectors associated with small singular values, although the order of an optimal truncation is difficult to determine. In this paper, a wavelet transformation is applied to reduce the computation time for inverse acoustics and to enhance the reconstructed vibration field. The computational speed-up is achieved, with solution time being reduced to $14.5\%$.

• Journal of Korea Society of Digital Industry and Information Management
• /
• v.10 no.1
• /
• pp.147-155
• /
• 2014

The rapid increase in the penetration rate and diverse utility of smart devices opens an opportunity for a development in creating a user-oriented ubiquitous system. And it allows audiences to deploy the exhibition-helping contents regardless of the restriction of place and time with using the smart devices of audience themselves. Also it needs to build a mobile web-based portal system for the related services. To do this, Firstly, it needs the corresponding strategies on a smartphone-based environment such as technical competence, systematic preparation of exhibition with compatible mobile contents, and a compatible channel for interactivity. Secondly, it needs the differentiation of exhibition guide with the existing system: an adoption of augmented reality, panoramic technology and simulation effect aiming for an improvement in a sense of immersion and reality for audience, and building up additional contents with a diversity of formats of image, sound, and video for customer satisfaction.

• Proceedings of the KIEE Conference
• /
• 1994.07b
• /
• pp.1609-1611
• /
• 1994

In ECR and helicon reactors for plasma processing, a high density plasma is generated in a source region which is connected to a diffusion region where the processing takes place. Large density and potential gradients can develop at the orifice of the source which drive ion currents into the diffusion region. The average ion velocity may become the order of the sound velocity. Measurements of the ion saturation current to a Langmuir probe are used as a standard method of determining the plasma density in laboratory discharges. However, the analysis becomes difficult in a steaming plasma. We have used the HAMLET plasma simulator to simulate the ion flow to a large langmuir probe in an ECR plasma. The collection surface was aligned with the Held upstream, normal to the field, and downstream. ion trajectories through the electric and magnetic fields were calculated including ion-neutral collisions. We examines the ratio of ion current density to plasma density as a function of magnetic field and pressure.

• Journal of the Korean Institute of Telematics and Electronics
• /
• v.20 no.6
• /
• pp.58-61
• /
• 1983

This is a Loudness Control Circuit in an audio amplifier controlled by feedback type volume control variable resistors. This circuit consists of Bridged Twin T network and a ordinary variable resistor. The variably resistor acts not only as a volume control by varying feedback qupntity, but also as Loudness Control through the characteristics variation by Sound Level. This new Loudness Control Circuit showed ideal compensation characteristics that agree computer simulation and measured datas.

• Journal of the Ergonomics Society of Korea
• /
• v.16 no.2
• /
• pp.101-122
• /
• 1997

Our recent work on virtual environments and virtual displays is reviewed, including our efforts to establish the Virtual Environment Research, Interactive Technology, And Simulation (VERITAS) facility and our research on spatial hearing. VERITAS is a state-of -the-art multisensory facility, built around the ${CAVE}^{TM}$ technology. High-quality 3D audio is included and haptic interfaces are planned. The facility will support technical and non-technical users working in a wide variety of application areas. Our own research emphasizes the importance of auditory stimulation in virtual environments and complex display systems. Experiments on auditory-aided visual target acquistion, sensory conflict, sound localization in noise, and loxalization of speech stimuli are discussed.

• Transactions of the Korean Society of Machine Tool Engineers
• /
• v.14 no.6
• /
• pp.68-73
• /
• 2005

Tire manufactures have dealt with noise problem by varying the pitch of the tread. The various formulas for the variations are generally determined differently, however. Often these variations are based on a combination of trial and error, intuition, and economics. Some manufactures have models and analogs to test tread patterns and their variations. These efforts, however practical, do not determine the best variation beforehand or guarantee the best results. For this reason it was felt that a general mathematical approach fur determining the best variation was needed. Moreover, the method should be completely general, easy to use, and sufficiently accurate. This paper discusses a mathematical method called Mechanical Frequency Modulation(MFM) which meets the above requirements. Thus, MFM pertains to computing an irregular time sequence of events so that the resulting excitation spectrum is shaped to a preferred form. The first part of this paper treats the theoretical basis for computing an optimum variation ; the second part discusses experimental results and simulation program which corroborate the theory.

• Journal of the Korean Institute of Telematics and Electronics B
• /
• v.28B no.10
• /
• pp.822-830
• /
• 1991

In this paper, we propose a new process for ultrasonic B-mode image considering the sound field effects of a concave circuit focused transducer, and aim to remove the speckle pattern which cause the blurring on boundary in ultrasonic B-mode image. We discuss in detail the conception of speckle pattern generation, and the frequency compounding method which is applied to the process for getting a speckle reduced B-mode image. Through the computer simulation, we define the meaning of speckle region, and show the results of reduced speckle pattern. It is discovered in the results that the frequency compounding method is very effective for boundary detection and that the application of the method is limited by various conditions.