• The Journal of the Korea Contents Association
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• v.4 no.1
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• pp.24-31
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• 2004

This paper embodies the rating recognition system of broadcast program which can automatically acknowledge the broadcast pictures indicating the harmfulness rating, so prevent children from watching TV. This experiment was progressed as the course of extracting featured patterns (standard number patterns) and the proper patterns owned only by the concerned numbers from the numbers of standard font used by broadcasters, and comparing these patterns with input pictures and arranging them. The recognition rate of x-rating was remarkably high as a result of this experiment.

• Journal of the Korean Society of Propulsion Engineers
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• v.20 no.5
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• pp.19-30
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• 2016

We presented a hydrodynamic modeling necessary to accurately reproduce shock-induced detonation of pyrotechnic initiator. The methodology for such numerical prediction of shock propagation is quite straight forward if the models are properly implemented and solved in a well-formulated shock physics code. A series of SSGT(Small Scale Gap Test) and detailed hydrodynamic simulation are conducted to quantify the shock sensitivity of an acceptor that contains 97.5% RDX. A TBI(Through Bulkhead Initiator) system, consisting of a train configuration of Donor(HNS+HMX) - Bulkhead(STS) - Acceptor(RDX), were investigated to further validate the interaction between energetic and non-reactive materials for predicting the detonating response for successful operation of such small pyro device.

• Journal of the Korean Society of Laryngology, Phoniatrics and Logopedics
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• v.17 no.2
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• pp.89-97
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• 2006

The stop consonants in Korean are classified into three types according to the manner of articulation as unaspirated (UA), slightly aspirated (SA) and heavily aspirated (HA) stops. Both the UA and the HA types are always voiceless in any environment. Generally, the voice onset time (VOT) could be measured spectrographically from release of consonant burst to onset of following vowel. The VOT of the UA type is within 20 msec of the burst, and about 40-50 msec in the SA and 50-70 msec in the HA. There have been many efforts to clarify properties that differentiate these manner categories. Umeda, et $al^{1)}$ studied that the fundamental frequency at voice onset after both the UA and HA consonants was higher than that for the SA consonants, and the voice onset times were longest in the HA followed by the SA and UA. Han, et $al^{2)}$ reported in their speech synthesis and perception studies that the SA and UA stops differed primarily in terms of a gradual versus a relatively rapid intensity build-up of the following vowel after the stop release. Lee, et $al^{3)}$ measured both the intraoral and subglottal air pressure that the subglottal pressure was higher for the HA stop than for the other two stops. They also compared the dynamic pattern of the subglottal pressure slope for the three categories and found that the HA stop showed the most rapid increase in subglottal pressure in the time period immediately before the stop release. $Kagaya^{4)}$ reported fiberscopic and acoustic studies of the Korean stops. He mentioned that the UA type may be characterized by a completely adducted state of the vocal folds, stiffened vocal folds and the abrupt decreasing of the stiffness near the voice onset, while the HA type may be characterized by an extensively abducted state of the vocal folds and a heightened subglottal pressure. On the other hand, none of these positive gestures are observed for the SA type. Hong, et $al^{5)}$ studied electromyographic activity of the thyroarytenoid and posterior cricoarytenoid (PCA) muscles during stop production. He reported a marked and early activation of the PCA muscle associated with a steep reactivation of the thyroarytenoid muscle before voice onset in the production of the HA consonants. For the production of the UA consonants, little or no activation of the PCA muscle and earliest and most marked reactivation of the thyroarytenoid muscle were characteristic. For the SA consonants, he reported a more moderate activation of the PCA muscle than for the UA consonant, and the least and the latest reactivation of the thyroarytenoid muscle. Hong, et $al^{6)}$ studied the observation of the vibratory movements of vocal fold edges in terms of laryngeal gestures according to the different types of stop consonants. The movements of vocal fold edges were evaluated using high speed digital images. EGG signals and acoustic waveforms were also evaluated and related to the vibratory movements of vocal fold edges during stop production.

• Journal of the Korea Society for Simulation
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• v.28 no.2
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• pp.1-14
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• 2019

A full scale hydrodynamic simulation that requires an accurate reproduction of shock-induced detonation was conducted for design of an energetic component system. A detailed hydrodynamic analysis SW was developed to validate the reactive flow model for predicting the shock propagation in a train configuration and to quantify the shock sensitivity of the energetic materials. The pyrotechnic device is composed of four main components, namely a donor unit (HNS+HMX), a bulkhead (STS), an acceptor explosive (RDX), and a propellant (BPN) for gas generation. The pressurized gases generated from the burning propellant were purged into a 10 cc release chamber for study of the inherent oscillatory flow induced by the interferences between shock and rarefaction waves. The pressure fluctuations measured from experiment and calculation were investigated to further validate the peculiar peak at specific characteristic frequency (${\omega}_c=8.3kHz$). In this paper, a step-by-step numerical description of detonation of high explosive components, deflagration of propellant component, and deformation of metal component is given in order to facilitate the proper implementation of the outlined formulation into a shock physics code for a full scale hydrodynamic simulation of the energetic component system.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2017.05a
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• pp.440-444
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• 2017

Two-dimensional hydrodynamic analysis was performed to analyze the attenuating characteristics of shock waves generated by the detonation of the bulkhead initiator. Through the interlocking analysis between HNS and HMX stacking initiator and STS bulkhead, we have precisely simulated detonation growth and pressure wave attenuation phenomena. The free surface velocity at the surface of the bulkhead was measured for quantitative comparison with the test data by VISAR. As a result, it was confirmed that the pressure attenuating pattern of the shock wave exponentially decreased according to the bulkhead thickness. The observed inflection point at the particle velocity measured over time is due to the subsequent propagation of the shock wave due to the rapid spallation of the interface between the detonator and the bulkhead.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2006.05a
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• pp.421-424
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• 2006

High nitrogen steels (HNS) exhibit both high strength and ductility during tensile deformation. In the present study the Fe-18Cr-14Mn-4Ni-0.9N high nitrogen steel was heat treated at $1000^{\circ}C$ and $1100^{\circ}C$ to produce $Cr_2N$ precipitates in austenite matrix and full austenite microstructures, respectively. Tensile tests of the heat treated specimens were performed at two different strain rates of 0.05/sec and 0.00005/sec. Each tensile curve of the specimens could be well characterized by the the modified Ludwik equation. Plastic deformation of the steel was adequately represented by the four parameters of the modified Ludwik equation. At 0.05/s strain rate, the specimen with the $Cr_2N$ precipitate exhibited higher strength than the full austenite specimen, while the full austenite specimen showed better mechanical properties at 0.00005/s strain rate. It was found that the $Cr_2N$ precipitates influences deformation behavior of the high nitrogen steel significantly.

• Proceedings of the KOSOMBE Conference
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• v.1997 no.11
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• pp.67-70
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• 1997

In this paper, we evaluated the character of speech of hearing impaired person (HIP) who acquire his hearing loss after the youth. It is usually observed that severe HIP decreased not only speech perception but also vocalization. so there is a need for sensitive and quantitative measures or the assesment of the speech of the HIP to serve both diagnostic and prognosic purposes, 7 HIP and 12 normal hearing person(NHP) were studied with pure tone test and speaking test using word/sentence table which consists of vowel(a:), mono and two syllables and a sentence. we analyzed formant frequency, pitch, sound intensity, speech duration of HIP and NHP speech. According to the results, in the HIP's speech we find that formant frequency was shifted, first-formant prominence was reduced, the dynamic range of sound intensity was decreased, speech duration was prolonged. In the next, we expect the correlation between hearing and speech character of HIP is cleared through analysis of more acoustic parameters and precise selection of HIP group.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.05a
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• pp.173-174
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• 2006

Understanding chondrocyte behavior inside complex, three-dimensional environments with controlled patterning of geometrical factors would provide significant insights into the basic biology of tissue regenerations. One of the fundamental limitations in studying such behavior has been the inability to fabricate controlled 3D structures. To overcome this problem, we have developed a three-dimensional microfabrication system. This system allows fabrication of predesigned internal architectures and pore size by stacking up the photopolymerized materials. Photopolymer SL5180 was used as the material for 3D scaffolds. The results demonstrate that controllable and reproducible inner-architecture can be fabricated. Chondrocytes harvested from human nasal septum were cultured in two kinds of 3D scaffolds to observe cell adhesion behavior. Such 3D scaffolds might provide effective key factors to study cell behavior in complex environments and could eventually lead to optimum design of scaffolds in various tissue regenerations such as cartilage, bone, etc. in a near future.

• Journal of the Korean Society of Propulsion Engineers
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• v.21 no.5
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• pp.80-87
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• 2017

The performance of a pyrotechnic device that consists of donor/acceptor pair separated by a bulkhead relies on shock attenuation characteristics of the gap material and shock sensitivity of the donor and acceptor explosives. In this research, a micro Kapton flyer was accelerated by an exploding foil initiator (EFI) to figure out shock sensitivity of hexanitrostilbene (HNS) to impact. The averaged shock pressure and duration imparted to the explosive by flyer impact are measured by using a velocity interferometer for any reflector (VISAR) and impedance matching technique. Consequently, this research shows the possibility to determine the critical flyer velocity for initiating the miniaturized pyrotechnic unit by determining the relations between the impact velocity, the amplitude and width of impact loading.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.33 no.3
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• pp.181-185
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• 2020

Hazardous and noxious substance (HNS) detection sensors were fabricated using multi-walled carbon nanotubes (MWCNTs) and various binder materials for ion batteries. To obtain uniformly printed films, the printing precision according to the substrate cleaning method was monitored, and the printing paste mixing ratio was investigated. Binders were prepared using styrene butadiene rubber + carboxymethyl cellulose (SBR+CMC), polyvinylidene fluoride + n-methyl-2-pyrrolidene (PVDF+NMP), and mixed with MWCNTs. The surface morphology of the printed films was examined using an optical microscope and a scanning electron microscope, and their electrical properties are investigated using an I-V sourcemeter. Finally, sensing properties of MWCNT printed films were measured according to changes in the concentration of the chemical under the various applied voltages. In conclusion, the MWCNT printed films made of (SBR+CMC) were found to be feasible for application to the detection of hazardous and noxious chemicals spilled in seawater.