• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.15 no.10 s.103
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• pp.1137-1147
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• 2005

The dynamic response due to the unbalance and crack and the quasi-static response due to gravity are analytically derived based on the complex transfer matrix. The additional slope is expressed as function of the bending moment at crack position based on the fracture mechanics concept, and inversely the bending moment is expressed as function of the additional slope at the crack Position. At each angle step during the shaft revolution, the additional slope and bending moment are calculated by an iterativemethod. The transient behavior is considered by introducing Fourier series expansion concept for the additional slope. Simulation is carried out for a simple rotor similar to those available in the literature and comparison of the basic crack behavior is shown. Using the additional slope, the cracked rotor behavior is explained with the crack depth increased: the magnitude of the additional slope increases and the closed crack duration during a revolution decreases as the crack depth increases. The direction of unbalance is also shown as a factor to affect the crack breathing. Whirl orbits are shown near the sub-critical speed ranges of the rotor.

• Convergence Security Journal
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• v.10 no.1
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• pp.55-61
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• 2010

It is of great practical interest to deciding when to stop testing a software system in development phase and transfer it to the user. This decision problem called an optimal release policies. In this paper, because of the possibility of introducing new faults when correcting or modifying the software, we were researched release comparative policies which based on infinite failure NHPP model and types of interval failure times. The policies which minimize a total average software cost of development and maintenance under the constraint of satisfying a software reliability requirement can optimal software release times. In a numerical example, applied data which were patterns, if intensity function constant or increasing, decreasing, estimated software optimal release time.

• Journal of the Korean Society of Radiology
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• v.11 no.5
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• pp.353-359
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• 2017

The sonophoresis, a representative low-intensity ultrasonic therapy, is a technique for delivering the drugs into the epidermis, dermis and skin appendages by using physical vibration and heat effects of the ultrasonic waves. Sonophoresis could increases the delivering and absorption efficiency of the drugs usually consisting of hydrophilic molecules and macromolecules. In addition, it has the advantage of being effective in delivering drugs with relatively large molecular sizes such as insulin or lipid. In this study, we proposed a multi-structure ultrasonic transducer assembly with a large-size single piezoelectric element and a drug delivery function at the treatment site for efficient sonophoresis treatment. Futhermore, a transducer assembly structure capable of raising and maintaining the temperature of the treatment site was proposed and evaluated for effectiveness. The transducer assembly proposed in this study is expected to improve the efficiency of sonophoresis by providing a constant amount of drug, and assisting drug delivery through heating the treatment site.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.22 no.10
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• pp.985-993
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• 2012

In this paper, a new method is proposed to estimate the sound pressure generated from gasoline direct injection (GDI) engine. There are many noise sources as much as components in GDI engine. Among these components, fuel pump, fuel injector, fuel rail, pressure pump and intake/exhaust manifolds are major components generated from top of the engine. In order to estimate the contribution of these components to engine noise, the total sound pressure at the front of the engine is estimated by using airborne source quantification (ASQ) method. Airborne source quantification method requires the acoustic source volume velocity of each component. The volume velocity has been calculated by using the inverse method. The inverse method requires many tests and has ill-condition problem. This paper suggested a method to obtain volume velocity directly based on the direct measurement of sound intensity and particle velocity. The method is validated by using two known monopole sources installed at the anechoic chamber. Finally the proposed method is applied to the identification and contribution of noise sources caused by the GDI components of the test engine.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.3
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• pp.32-39
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• 2018

Raman spectra exhibit differences in intensity depending on the measuring equipment and environmental conditions even for the same material. This restricts the pattern recognition approach of Raman spectroscopy and is an issue that must be solved for the sake of its practical application, so as to enable the reusability of the Raman database and interoperability between Raman devices. To this end, previous studies assumed the existence of a transfer function between the measurement devices to obtain a direct spectral correction. However, this method cannot cope with other conditions that cause various intensity distortions. Therefore, we propose a classification method using linear intensity calibration which can deal with various measurement conditions more flexibly. In order to evaluate the performance of the proposed method, a Raman library containing 14033 chemical substances was used for identification. Ten kinds of chemical Raman spectra measured using three different Raman spectroscopes were used as the experimental data. The experimental results show that the proposed method achieves 100% discrimination performance against the intensity-distorted spectra and shows a high correlation score for the identified material, thus making it a useful tool for the identification of chemical substances.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.12 no.4
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• pp.61-68
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• 2013

As an advance study for the development of a heat sink for special purpose high power illumination, an investigation was made to find feasibility for the application of copper plated EP to a heat sink of small LED light of less than 10W installed in commercial product. In this study, the plated heat sink with EP copper was fabricated for the conventional LED light. It was used actually for finding heat radiation property and effectiveness of the heat sink accompanied with measurement of luminous intensity. The heat is radiated by transfer and dissipation only through the copper plated surface due to extremely low heat conductivity of EP in case of EP heat sink; however the total area of the plate plays the function of heat transfer as well as heat radiation in case of the aluminum heat sink. It seems that the volume difference of heat radiating material is so big that the temperature $P_1$ is 9.0~12.3% higher in 3W and 42.7~54.0% higher in case of 6W volume difference of heat radiating material is so big that the temperature $P_1$ is 9.0~12.3% higher in 3W and 42.7~54.0% higher in case of 6W even though heat transfer rate of copper is approximately 1.9 times higher than that of aluminum. It was thought that this is useful to utilize for heat sink for low power LED light with the low heating rate. Also, the illumination could be greatly influenced by the surrounding temperature of the place where it is installed. Therefore, it seems that the illumination installation environment must be taken into consideration when selecting illumination. Further study was expected on order to aims at development of an exterior surface itself made into heat radiation plate by application of this technology in future.

• Journal of the Korean institute of surface engineering
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• v.45 no.1
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• pp.15-19
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• 2012

Tris(8-quinolinolato)aluminum(III); $Alq_3$ has been frequently used as an electron transporting layer in organic light-emitting diodes. Either Ba with a low work function or Au with a high work function was deposited on $Alq_3$ layer in vacuum. And then, the behaviors of electron transition at the $Alq_3$/Ba and $Alq_3$/Au interfaces were investigated by using the near edge x-ray absorption fine structure (NEXAFS) spectroscopy. In the each interface, the energy levels of unoccupied obitals were assigned as ${\pi}^*$(LUMO, LUMO+1, LUMO+2 and LUMO+3) and ${\sigma}^*$. And the relative intensities of these peaks were investigated. In an oxygen atom composing $Alq_3$ molecule, the relative intensities for a transition from K-edge to LUMO+2 were largely increased as Ba coverage (${\Theta}_{Ba}$, 2.7 eV) with a low work function was in-situ sequentially increased on $Alq_3$ layer. In contrast, the relative intensities for the LUMO+2 peak were reduced as Au coverage (${\Theta}_{Au}$, 5.1 eV) with a high work function were increased on $Alq_3$ layer. This means that the electron transition by photon in oxygen atom which consists in the unoccupied orbitals in $Alq_3$ molecule, largely depends on work function of a metal. Meanwhile, in the case of electron transition in a carbon atom, as ${\Theta}_{Ba}$ was increased on $Alq_3$, the relative intensity from K-edge to ${\pi}_1{^*}$ (LUMO and LUMO+1) was slightly decreased, and from K-edge to ${\pi}_2{^*}$ (LUMO+2 and LUMO+3) was somewhat increased. This rising of the energy state from ${\pi}_1{^*}$ to ${\pi}_2{^*}$ exhibits that electrons provided by Ba would contribute to the process of electron transition in the $Alq_3$/Ba interfaces. As shown in above observation, the analyses of NEXAFS spectra in each interface could be important as a basic data to understand the process of electron transition by photon in pure organic materials.

• Journal of Korean Society of Transportation
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• v.27 no.4
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• pp.195-206
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• 2009

The deregulation of aviation markets in Europe and the United Sates had led airlines to reconfigure their networks into hub-and-spoke systems. Recent trends of "Open Skies" in the Asian aviation market are also expected to prompt the reformation of airlines' networks in the region. A significant connectivity index is a crucial tool for airlines and airport authorities to estimate the degree of hub-and-spoke operations. Therefore, this paper suggests a new index, Continuous Indirect Connectivity Index (CICI), for measuring the coordination of airlines' flight schedules, applying it to the Asian, European and the American aviation markets. CICI consists of three components：(i) temporal connectivity to identify the attractiveness between connection flights, (ii) spatial connectivity to differentiate the attractiveness by de-routing distance with continuous linear function, and (iii) relative intensity to reflect the effect of direct flight frequency on transfer routes. CICI is evaluated to examine a casual relationship through regression analyses with two dependent variables of the number of transfer passengers and transfer rates. Compared with Danesi's index and Doganis' index through evaluation processes, CICI has a higher coefficient value of determination, implying that it explains the relationship between connectivity and transfer passengers more precisely.

• Korean Journal of Remote Sensing
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• v.27 no.3
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• pp.213-223
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• 2011

The purpose of this study is to estimate the spherical wave parameters that appears in synthetic aperture radar (SAR) image acquired over the coast of Chukk, Micronesia. The retrieval of ocean wave parameters consists of two main stages: the first is to determine the dominant wavelengths by Fast Fourier Transform (FFT) over 16 sub-image areas and the second is to estimate wave slopes and heights using dispersion relationship under various water wave conditions. It is assumed that the spherical waves are linear and progressive. These type of waves have the range and azimuth components traveling in radial directions. The azimuth travelling waves are more affected by the velocity bunching mechanism and it is difficult to estimate the wave parameters for these affected areas in SAR imagery. In order to compensate these effects, the velocity bunching ratio (VBR) based on modulation transfer function (MTF) was compared with the intensity ratio for neighbor area in the radial direction in order to assign the spherical wave properties for azimuthally travelling waves. Dispersion relation provides the good estimates for the wave heights for all the selected sub-image areas in the range of 1m to 2m. VBR based on MTF was found to be 0.78 at wave height of 1.36m, while the intensity-based VBR was 0.69 which corresponds to the height of 1.75m. It can be said that the velocity bunching accounts for azimuthally travelling spherical waves and the difference results from the sea-bottom effects.

• Journal of Microbiology and Biotechnology
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• v.10 no.3
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• pp.300-306
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• 2000

The rate of apparent nitric oxide (NO) release, as measured in the exhaust gas of green alga, Scenedesmus obliquus, depended on the light intensity and pH. It doubled after lowering the temperature from $25^{\circ}C{\;}to{\;}15^{\circ}C$ and strongly decreased from $35^{\circ}C{\;}to{\;}42^{\circ}C$. The Scenedesmus cells, deficient in nitrogen or phosphorus, demonstrated a significant increase in NO production following their transfer to nitrate- and phosphate-rich media. The addition of herbicides (DCMU and glyphosate) or toxic concentrations of $Cu^{2+}{\;}or{\;}Fe^{3+}$ produced strong NO peaks, resembling those that occurred after sudden darkening. An increase in the $Ni^{2+}$ concentration to 20 ppm resulted in a gradual increase of NO release from the initial ~1.5 ppbv to>20 ppbv, whereas $Cd^{2+}$ instantaneously suppressed the NO by the cultures of Scenedesmus was not altered by L-NNA, an inhibitor of nitric oxide synthase (NOS), or by its substrate, L-arginine. This seems to exclude the role of NOS in the NO formation under study. Accordingly, it can be assumed that the rate of NO formation is mainly a function of dynamic nitrite pool sizes and environmental factors significantly affect the NO production in algae.