• Transactions of the Korean Society of Machine Tool Engineers
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• v.18 no.1
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• pp.68-75
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• 2009

A major disadvantage of thermal nanoimprint lithography(NIL) is the thermal cycle, that is, heating over glass transition temperature and then cooling below it, which requires a significant amount of processing time and limits the throughput. One of the methods to overcome this disadvantage is to make the processing temperature lower Accordingly, it is necessary to determine the effects on the processing parameters for thermal NIL at reduced temperatures and to optimize the parameters. This starts with a clear understanding of polymer material behavior during the NIL process. In this work, the squeezing and filling of thin polymer films into nanocavities during the low temperature thermal NIL have been investigated based upon a two-dimensional viscoelastic finite element analysis in order to understand how the process conditions affect a pattern quality; Pressure and initial polymer resist thickness dependency of cavity filling behaviors has been investigated.

• Transactions of the Korean hydrogen and new energy society
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• v.30 no.1
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• pp.67-75
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• 2019

An experimental study was conducted to measure laminar burning velocity and Markstein length of SNG fuel with 3% of hydrogen contents from spherical propagating flames at normal and elevated initial pressure. These results were compared with numerical calculations by Premix code with GRI-mech 3.0, USC II and UC San Diego to provide suitable mechanism for SNG fuel. As a result of this work, it was found that the burning velocities and Markstein lengths of SNG fuel decrease with increase of initial pressure regardless of equivalence ratio. In addition, numerical calculations with GRI-mech 3.0 were coincided with experimental results.

• Proceedings of the KSPS conference
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• 1996.10a
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• pp.390-398
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• 1996

Acoustic analysis study was performed on 20 normal subjects by speaking nonsense syllables composed of Korean bilabial stops(/p, $p^{*}$/, ph/) and their Preceding and/or following vowel /a/(that is, [pa, $p^{*}a$, pha, apa, $ap^{*}a$, apha]) with an ultraminiature pressure sensor in their mouths. Speech materials were phonated twice, once with a moderate voice, another time with a loud voice. The acoustic signal and intraoral pressure were recorded simultaneously on computer. By these procedures, we were to measure the intraoral pressure, closure duration and VOT of Korean bilabial stops, and to compare the values one another according to the intensity of phonation and the position of the target consonants. Intraoral pressure was measured by the peak intraoral pressure value of its wave; closure duration by the time interval between the onset of intraoral pressure build-up and the burst meaning the release of closure; Voice onset time(VOT) by the time interval between the burst and the onset of glottal vibration. Heavily aspirated bilabial stop consonant /ph/ showed the highest intraoral pressure value, unaspirated /p$^{*}$/, the second, slightly aspirated /p/, the lowest. The syllable initial bilabial stops showed higher intraoral pressure than word initial stops, and the value of loudly phonated consonants were higher than moderate consonants. The longest closure duration period was that of /$p^{*}$/ and the shortest, /p/, and the duration was longer in word initial position and in the moderate voice. In VOT, the order of the longest to shortest was /ph/, /p/, /$p^{*}$/, and the value was shorter when the consonant was in intervocalic position and when it was phonated with a loud voice.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.27 no.11
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• pp.1595-1603
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• 2003

Droplet combustion at high ambient pressures is studied numerically by formulating one dimensional combustion model in the mixture of n-heptane fuel and air. The ambient pressure is supercritical conditions. The modified Soave-Redlich-Kwong state equation is used in the evaluation of thermophysical properties to account for the real gas effect on fluid p-v-T properties in high pressure conditions. Non-ideal thermodynamic and transport property at near critical and supercritical conditions are also considered. Several parametric studies are performed by changing ambient pressure and initial droplet diameter. Droplet lifetime decreased with increasing pressure. Surface temperature increased with increasing pressure. Ignition time increased with increasing initial droplet diameter. Temporal or spatial distribution of mass fraction, mass diffusivity, Lewis number, thermal conductivity, and specific heat were presented.

• Journal of the Korean Society for Precision Engineering
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• v.12 no.1
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• pp.68-77
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• 1995

The two-dimensional pressure distribution, which is the most important parameter in the casting cleaning installations(CCI), was analyzed using the K-FIX computer program for two-phase flow. Modelling was done using R-Z coordinates for the initial and boundary conditions which don't have periodic influx and efflux, and also there was the electric discharge due to high pressure and temperature. The marked particles were introduced to prodict the structure and the size of main and local moving surfaces. The initial and boundary conditions were modified due to the internal structure of CCI.From the results of numerical analysis, it was shown that the maximum pressure on casting was increased with the increase of a water level. The pressure on casting in the radial direction was higher than that in axial direction. Also, it was proved that by introducing the marked particles it was possible to predict the surface structure in case of two-phase flow.

• Archives of Plastic Surgery
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• v.37 no.3
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• pp.245-249
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• 2010

Purpose: High-pressure injection injury is caused by accidental injection of the high-pressure injection devices in industry. The initial benign appearance of the wound fools patients into delays in an adequate treatment. And it can result in disastrous outcomes such as necrosis and amputation. To avoid the poor prognosis, the injuries require a prompt surgical intervention. The purpose of this article is to recognize the poor outcome of the highpressure injection injury and to introduce an adequate treatment in need. Methods: We have 4 cases of the high-pressure injection injuries in the hand from April, 2005 to March, 2009. Average age is 39 years (30 - 49 years old), 2 cases are the palm of dominant hand, 1 case is the thumb of dominant hand, and 1 case is the palm of non-dominant hand, respectively. We followed up these patients for 20 months on average. In 3 cases, the immediate, aggressive surgical intervention was carried out, but the other one was delayed in early adequate treatment. The wounds were covered by local advancement flap, anterolateral thigh free flap, conservative treatment with antibiotics and dressing. Results: No pathogens after culture were found nor any findings of fracture in imaging study. Conservative treatment, local advancement flap and anterolateral thigh free flap for the open wound resulted in a desirable aesthetic outcome. In a long-term follow up, functional capability of the patient was also satisfactory. Conclusion: Upon initial evaluation, most high-pressure injection injuries present as innocuous wounds with very few symptoms and result in delaying the proper management. And the majority of high-pressure injection injuries will produce significant morbidity to the hand, amputation. And the initial aggressive surgical debridement was needed to prevent the poor outcome. The key to success in treating high-pressure injection injuries of the hand is the prompt aggressive surgical intervention.

• Bulletin of the Society of Naval Architects of Korea
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• v.20 no.4
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• pp.1-8
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• 1983

This paper describes the application of the finite element method to the large deflection elastic plastic analysis and ultimate load calculation of axisymmetric shell of revolution with initial imperfection subjected to external pressure. The nonlinear equilibrium equations are linearized by the successive incremental method and are solved by the combination of load increment and iteration scheme with considering plastic deformation theory. To get the more realistic effect of large deflection, corrected coordinats and directions of applied load ar every load increment steps are used. The effects of the plasticity, initial imperfection and the shape of shells on the ultimate load of clamped circular cap under external pressure are investigated. Consequently, the following conclusions are obtained; (1) At same geometric parameter $\lambda$, each shape of clamped circular caps yield same elastic ultimate loads in both cases, i.e. with and without initial imperfections, whereas, in the case of elastic-plastic state the shell becomes thicker, the ultimate loads are getting smaller. (2) The effects of initial imperfection to ultimate load are most significant in the elastic case and are more senstive in the elastic-plastic state with the thinner shells.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.24 no.12
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• pp.1608-1614
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• 2000

For the purpose of obtaining fundamental data which is needed to develope combustion system of LPG engine, we made constant volume chamber and analyzed flame propagation characteristics under different intial temperature, initial pressure and equivalence ratio which affect combustion of LPG. We investigated flame propagation speed of each fuel using laser deflection method and compared with the investigated flame propagation speed of each fuel using laser deflection method and compared with the results of image processing of flame. As a result, the maximum flame propagation speed was found at equivalence ratio 1.0 and 1.1 for LPG and gasoline, respectively. In the lean region, we can see that flame propagation speed of LPG surpasses that of gasoline. On the contrary, flame propagation speed of gasoline surpasses LPG in the rich region. As initial temperature and initial pressure were higher, flame propagation speed was faster. And, as equivalence ratio was larger and initial temperature was higher, combustion duration was shorter and maximum combustion pressure was higher.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.11a
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• pp.136-139
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• 2002

Previous valves have initial gap problem, high voltage or high pressure problem. In this paper, various micro valves with free floating structure have been fabricated and tested to solve the initial gap and high pressure problems. The paper presents how to etch Parylene-C which is a valve cap material without A1 mask layer. The maximum flow-rate of fabricated micro valve is$118{\mu\ell}$/min with $370{\mu}m$ orifice size and the leakage at the initial and reverse pressure is not observed.

• Journal of the Korean Ceramic Society
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• v.42 no.1
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• pp.22-27
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• 2005

The preparation of B4C by SHS in $B_{2}O_{3}-Mg-C$ system was investigated in this study. In the preparation of B4C, the effect on reactivity and reaction products of the initial pressure of inert gas in reactor, the content of Mg and C in mixture was investigated. The minimum initial pressure of inert gas in reactor for SHS reaction in this system was 25 atm, and as the pressure increased, the concentration of unreacted Mg decreased and combustion temperature increased. At the initial inert gas pressure in reactor of 25 atm, the optimum composition for the preparation of pure B4C was $2B_{2}O_{3}+6.3Mg +0.94C$. The B4C synthesized in this condition had an irregular shape and the particle size of $1\~3{\mu}m$.