• 유체기계공업학회:학술대회논문집
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• 2006.08a
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• pp.205-208
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• 2006

This paper proposes a new computational aeroacoustics method for an axial fan analysis. The major aeroacoustic noise source of an outdoor air-conditioner is the axial fan. It was revealed that the dominant noise source is the aerodynamic interactions between the rotating blade and stationary orifice. Many researches were focused on the fan only case. However, it does not fit to a real outdoor unit of air-conditioner. Especially, the inlet part of the axial fan of real system case is complex and not uniform. So, in order to identify the dominant noise source of axial fan, full outdoor unit analysis is important. Transient CFD analysis of full system was performed by commercial CFD code - SC/Tetra. Dominant noise source of the system was calculated by commercial CFN code - FlowNoise. The results show that not only BPF peaks but also broadband noise are similar to the measured data.

• Proceedings of the KSME Conference
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• 2000.11b
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• pp.321-327
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• 2000

This study represents numerical analysis in top opening rectangular with a heating source. The governing equations were solved by a finite volume method, a SIMPLE algorithm was adopted to solve a pressure term. The top boundary with free surface was calculated by energy balance condition. As the results of simulations, the magnitudes of the velocity vectors and isotherms were very small at the lower space of a heating source. The mean Nusselt numbers are increased proportionally to the Grashof number, the heat transfer at Y/H=0.25 was greater than other positions.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.27 no.10
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• pp.1623-1629
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• 2003

In this paper, the arc beam is considered as a moving disc heat source with a pseudo-Gaussian distribution of heat intensity. The solution for temperature distribution on welds is derived by using the image heat source method and the superposition method. It is general solution in that it can determine the temperature-rise distribution in and around the arc beam heat source, as well as the width and depth of the melt pool (MP) and the heat-affected zone (HAZ) in welding short lengths, where quasi-stationary conditions may not have been established. As a comparative study, the results of this analytical approach has been compared with that of the finite-element modeling. As a result, The theoretical analysis presented here has shown good consistency and is more time/cost-effective method compared with FEM.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2011.04a
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• pp.71-76
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• 2011

In this paper, we investigate the vibration source of sheet feeding apparatus installed in scanner cover of the digital MFP through frequency analysis. Gearmesh frequency and motor generated frequency were calculated to analyse autospectrum. During driving state, we measure the vibration level. It was found from the signal analysis that gearmesh frequency and motor generated frequency are identified as vibration source.

• Journal of the Optical Society of Korea
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• v.12 no.3
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• pp.121-125
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• 2008

We address the problem of Blind Source Separation(BSS) of superimposed signals in situations where one signal has constant or slowly varying intensities at some consecutive locations and at the corresponding locations the other signal has highly varying intensities. Independent Component Analysis(ICA) is a major technique for Blind Source Separation and the existing ICA algorithms fail to estimate the original intensities in the stated situation. We combine the advantages of existing sparse methods and Kernel ICA in our technique, by proposing wavelet packet based sparse decomposition of signals prior to the application of Kernel ICA. Simulations and experimental results illustrate the effectiveness and accuracy of the proposed approach. The approach is general in the way that it can be tailored and applied to a wide range of BSS problems concerning one-dimensional signals and images(two-dimensional signals).

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2018.10a
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• pp.238-240
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• 2018

Recently, healthcare services have been developed and studied using various bio-signal analysis tools. Most bio-signal analysis studies utilize Matlab and R Programming. However, in order to apply the algorithm developed by Matlab and R Programming to the system, it is necessary to convert the source code. This paper proposes a smart interface that can skip source code conversion.

• Proceedings of the KIPE Conference
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• 2005.07a
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• pp.647-650
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• 2005

The paper aims on an analysis for dc boost control using Z-source inverter. The modified space vector PWM method is used for controlling both the dc boost and ac output controls in the Z-source inverter. The capacitor voltage and the voltage stress of device with both the shoot-through time and modulation index are analyzed considering the zero state time of inverter. The theoretical analysis is verified with the simulation studies and experiments with 32-bit DSP.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.15 no.2
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• pp.31-37
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• 2001

This paper propose ZVS-HB type resonant DC/DC converter have earth different output characteristics using division ratio, not only a source division function but a resonant function and soft switching technique(ZVS, ZCS) instead of conventional source division capacitor. Circuit analysis generally described using normalized parameters most of characteristics with division ratio of source division capacitor. Also, this paper citified a rightfulness of characteristic analysis in comparison with a theoretical values and a experimental values obtain from experiment using Power-MOSFET.

• Proceedings of the KIPE Conference
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• 2007.07a
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• pp.40-42
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• 2007

Recently the harmonic generation has deteriorated the quality of electricity and affected the performance on the electrical installation including personal computer, fax, community devices and so on. Some studies of harmonic affects in diagnosis and the cause of accident has not done by the experimental data of harmonic source but merely by presumption according to qualitative analysis. So, in order to research the harmonic affect on the electrical installation according to quantitative analysis and gather reliable data over and over again, it is necessary to develop an Harmonic power source which is capable of generating some harmonics. In this paper, we described about realization of Harmonic power source control module which can produce and added harmonics for the analysis due to harmonic effects.

• Mass Spectrometry Letters
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• v.11 no.4
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• pp.95-102
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• 2020

In this study, we provide full descriptions of how to make a low-cost and completely open-source laboratory-made air sampler that will be used for sample adsorption for thermal desorption-gas chromatography mass spectrometry (TD-GC/MS) analysis. It is well known that harmful gases cause bad effects on human bodies, so it is necessary to identify the types and amounts of gases in industrial sites. One of the most commonly used methods for gas sampling is to utilize a sorbent tube using an air sampler. Commercially available air samplers are expensive, typically priced between $1,000 and $2,000, and their design often cannot be modified to fit the experiment. To address these shortcomings, we have developed a do-it-yourself (DIY) air sampler that is not only cheap enough, but also completely open-source. Furthermore, the performance of the fabricated air sampler was validated in conjunction with TD-GC/MS for the analysis of volatile compounds.