• 한국자동차공학회논문집
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• 제11권1호
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• pp.55-63
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• 2003

In a diesel engine, air-fuel mixture formation and ignition delay period have great influence on the performance of engine. Their main factors are combustion chamber shape, fuel injection system. air volume, air flow and so on. So, the combustion process in the cylinder is complex because of many factors which have direct and indirect effects on it. In this study, we take into consideration of scavenging pressure and scavenging temperature that are hewn as the main factor to the combustion process of two-stroke D.1. diesel engine. It is taken a picture of the combustion flame process for combustion chamber of re-entrant type and cylindrical type. So, it is applied to the basis data of combustion chamber design from an image analysis.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2001년도 제22회 KOSCI SYMPOSIUM 논문집
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• pp.139-146
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• 2001

The experimental study was carried out for the diffusion flame characteristics of second stage combustor with the variations of temperature and supplying rate of hot exhaust gas from first stage combustor. It also examined the flame structure and NOx formation of the second stage combustor in which the fuel(natural gas) is supplying into the mixture of oxygen hot exhaust gas from first stage combustor. The results show that the increasement of temperature and flow rate of exhaust gas lead to increase the NOx up to 30ppm with 19% $O_2$ condition

• 전자공학회논문지D
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• 제34D권5호
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• pp.45-51
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• 1997

Low temperature activation of dopants which were doped using ion mass doping system in amorphous silicon(a-Si) thin films was investigated. With a 20.angs.-thick Ni film on top of the a-Si thin film, the activation temperature of dopants lowered to 500.deg. C. When the doping was performaed after the deposition of Ni thin film on the a-Si thin films (post-doping), the activation time was shorter than that of dopants mass, the activation time of the dopants doped by pre-doping method increased. It turned NiSi2 formation, while the decrease of activation time was mainly due to the enhancement of the NiSi2 formation by mixing of Ni and a-Si at the interface of Ni and a -Si thin during the ion doping process.

• E2M - 전기 전자와 첨단 소재
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• 제8권1호
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• pp.64-70
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• 1995

We discussed the thermal analysis for a recording media with the variation of the laser pulse duration, the laser power and the temperature distribution in order to optimize the Te-based antireflection structure from the computer calculations. In the case that the radial heat diffusion is negligible, we can calculate the maximum temperature of the recording layer at the center of the spot by the Simple Model. The temperature profile of the recording layer is obtained from the Numerical Model by considering the total specific heat and the latent heat. As a result, the effect of the heat sinking acting as a thermal loss for the hole formation could be minimized by introducing the pulse with the hole formation duration(.tau.) below the thermal time constant(.tau.$_{D}$) of a dielectric layer. These requirments can be satisfied by using the dielectric thickness of the 2nd ART(Anti-Reflection Trilayer) condition or the dielectric materials with a low thermal diffusivity.y.

• 대한기계학회논문집
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• 제19권7호
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• pp.1720-1730
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• 1995

Finite-difference analysis was conducted to study the natural convection of a stably stratified salt-water solution in an annulus due to lateral heating. The main purpose of this study is to examine in detail the multi-layered flow structure. Calculation was thus made for R $a_{\eta}$=2*10$^{5}$ and 6.5*10$^{5}$ . Formation of layered flow structure, merging process of layers, the corresponding temperature and concentration distributions, Nusselt number variations with time are examined. Numerical results show that in each layer, the temperature profile looks 'S`-shaped and the concentration profile is uniform due to the convective mixing. The formation of the roll and the layer is governed by natural convection due to the temperature gradient and the merging process of the layer by diffusion of the concentration.ation.

• 열처리공학회지
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• 제13권4호
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• pp.253-258
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• 2000

The present study aimed to develop the TRIP(transformation induced plasticity) aided high strength low carbon steel sheets using reverse transformation process. The cold-rolled 0.14C-6.5Mn steel was reverse-transformed by slow heating to intercritical temperature region and air cooling to room temperature. An excellant combination of tensile strength and elongation of $98.3kgf/mm^2$ and 44.4% appears. This combination comes from TRIP phenomena of retained austenite during deformation. The stability of retained austenite Is very Important for the good ductility and it depends on diffusion of carbon and manganese during reverse transformation. The air cooling after holding at intercritical temperature retards the formation of pearlite and provides the carbon enrichment in retained austenite, resulting the increase of elongation in cold-roiled TRIP steel.

• Carbon letters
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• 제11권4호
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• pp.304-310
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• 2010

To manufacture a carbon/carbon composite the coal tar pitch was used as the matrix precursor and the PAN (polyacrylonitrile)-based carbon fiber was used as the reinforcing material to weave 3-directional preform. For pressure carbonization HIP equipment was used to produce a maximum temperature of $1000^{\circ}C$ and a maximum pressure of 100 MPa. The carbonization was induced by altering the dwell temperature between $250^{\circ}C$ and $420^{\circ}C$, which is an ideal temperature for the moderate growth of the mesophase nucleus that forms within the molten pitch during the pressure carbonization process. The application of high pressure during the carbonization process inhibits the mesophase growth and leads to the formation of spherical carbon particles that are approximately 30 nm in size. Most particles were spherical, but some particles were irregularly shaped. The spread of the carbon particles was larger on the surface of the carbon fiber than in the interior of the matrix pocket.

• 반도체디스플레이기술학회지
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• 제2권4호
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• pp.31-35
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• 2003

We present a formation technique of thin film heater for heat transfer components. Thin film structures of Cr-Si have been prepared on top of alumina substrates by magnetron sputtering. More samples of Mo thin films were prepared on silicon oxide and silicon nitride substrates by electron beam evaporation technology. The electrical properties of the thin film structures were measured up to the temperature of $500^{\circ}C$. The thickness of the thin films was ranged to about 1 um, and a post annealing up to $900^{\circ}C$ was carried out to achieve more reliable film structures. In measurements of temperature coefficient of resistance (TCR), chrome-rich films show the metallic properties; whereas silicon-rich films do the semiconductor properties. Optimal composition between Cr and Si was obtained as 1 : 2, and there is 20% change or less of surface resistance from room temperature to $500^{\circ}C$. Scanning electron microscopy (SEM) and Auger electron spectroscopy (AES) were used for the material analysis of the thin films.

• 한국표면공학회지
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• 제24권2호
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• pp.73-79
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• 1991

Recent studies son surface coatings have shown that the change of physical, chemical and crystallographic structure analysed and observed according to the deposition process variables has the effects on the resultant film properties. Under the same preparation condition conditions of the substrate and process variables, physical morphology variations characterized by substrate temperature and bias which offect the surface mobility of adatom and adhesion variations related to the formation of Ti interlayer were considered in the present study. Microhardness showed the highest value around 40$0^{\circ}C$ of the substrate temperature and increased with the substrate bias. Adhesion was improved with the increase of substrate temperature and bias. An interlayer of pure titanium formed prior to deposition of TiN improves the adhesion at its optimum thickness. These results were explained by the change of physical morphology and phase analysis.

• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2016년도 추계학술대회 논문집
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• pp.107-107
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• 2016

TiCrAlSiN films were developed in order to improve the high-temperature oxidation resistance, corrosion resistance, and mechanical properties of conventional TiN films that are widely used as hard films to protect and increase the lifetime and performance of cutting tools or die molds. In this study, a nano-multilayered TiAlCrSiN film was deposited by cathodic arc plasma deposition. It displayed relatively good oxidation resistance at $700-900^{\circ}C$, owing to the formation protective oxides of $Al_2O_3$, $Cr_2O_3$, and $SiO_2$, and semiprotective $TiO_2$. At $1000^{\circ}C$, the increased temperature led to the formation of the imperfect oxide scale that consisted primarily of the outer ($TiO_2$,$Al_2O_3$)-mixed scale and inner ($TiO_2$, $Al_2O_3$, $Cr_2O_3$)-mixed scale.