• Journal of the Semiconductor & Display Technology
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• v.15 no.2
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• pp.32-37
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• 2016

Sidewall angle (SWA) of an absorber stack in extreme ultraviolet lithography mask is considered to be $90^{\circ}$ ideally, however, it is difficult to obtain $90^{\circ}$ SWA because absorber profile is changed by complicated etching process. As the imaging performance of the mask can be varied with this SWA of the absorber stack, more complicated optical proximity correction is required to compensate for the variation of imaging performance. In this study, phase shift mask (PSM) is suggested to reduce the variation of imaging performance due to SWA change by modifying mask material and structure. Variations of imaging performance and lithography process margin depending on SWA were evaluated through aerial image and developed resist simulations to confirm the advantages of PSM over the binary intensity mask (BIM). The results show that the variations of normalized image log slope and critical dimension bias depending on SWA are reduced with PSM compared to BIM. Process margin for exposure dose and focus was also improved with PSM.

• The Korean Journal of Ecology
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• v.12 no.4
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• pp.257-284
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• 1989

This study was carried out to characterize pinus densiflora forests in middle province (Mt. Seolag, Mt. Taebaik) south province (Mt. Sokli, Mt. Jiri) and south-coast province (Mt. Daedun) of Korea. The appearance species in the P. densiflora alliance included 325 taxa and varied according to the direction of slopes. The steeper the slope was, the fewer number of taxa were observed. The floristic composition of south-coast province was gradually changing to the south hemispheric factors. Dominant species groups of P. densiflora alliance were classified into P. densiflora, Quercus serrata ( layer), Rhus trichocarpa ( layer), Lespedeza maximowiczii var. tomentella (S layer), Artemisia keiskeana, Carex humilis var. nana, Spodiopogon sibiricus (K layer). Quercus variabilis, Fraxinus sieboldiana and Styrax japonica association were formed under the P. densiflora alliance. Quercus, Rhus, Lespedeza and Rhododendron groups maintained high ecological relationships one another. The soil factors (pH, organic matters, and water field capacity)and relative light intensity tended to show negative correlation, which were significantly different among provinces. The P. densiflora forests of Korea were classified into one alliance and four associations, that is, pinion densiflorae Suz.-Tok. 1966, Quercetum variabilae ass. nov., Quercetum mongolicae ass. nov. Fraxinetum sieboldianae ass. nov. and Styraxetum japonicae ass. nov.

• Journal of the Korean Chemical Society
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• v.36 no.3
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• pp.442-445
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• 1992

Optical type hydrometer has been designed and constructed utilizing the fact that the refractive index of solution is varied in accordance with its specific gravity. Optical hydrometer produces the electric singal output with reflection of light in accordance with its specific gravity. This can be applied to continuous monitoring and/or automatic control of the specific gravity of solution. U-shaped glass rod was used a transfer medium of light, and the electronic circuit which utilize phase sensitive detection technique was designed to measure accurately the intensity of light. The specific gravity of sulfuric acid was measured with this hydrometer and the results show good linearity of output signal with its specific gravity.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.25 no.3
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• pp.356-365
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• 2001

Heat (mass) transfer characteristics have been investigated on the endwall of a large-scale linear turbine cascade. Its profile is based on the mid-span of the first-stage rotor blade in a industrial gas turbine. By using the naphthalene sublimation technique, local heat (mass) transfer coefficients are measured for two different free-stream turbulence intensities of 1.3% and 4.7%. The results show that local heat (mass) transfer Stanton number is widely varied on the endwall, and its distribution depends strongly on the three-dimensional vortical flows such as horseshoe vortices, passage vortex, and corner vortices. From this experiment, severe heat loads are found on the endwall near the blade suction side as well as near the leading and trailing edges of the blade. In addition, the effect of the free-stream turbulence on the heat (mass) transfer is also discussed in detail.

• Proceedings of the KSME Conference
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• 2008.11b
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• pp.3013-3018
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• 2008

Supercharging system was adopted to investigate the influence of boost pressure on operating range, brake specific fuel consumption (BSFC) and exhaust emissions by using a supercharger at low temperature diesel combustion (LTC) condition in a 5-cylinder 2.7 L direct injection diesel engine. The experimental parameters such as injection quantity, injection timing, injection pressure and exhaust gas recirculation (EGR) rate were varied to find maximum operating range. The result showed that operating range with boost was expanded up to 41.9% compared to naturally aspirated LTC condition due to increased mixing intensity. The boosted LTC engine showed low BSFC value and dramatically reduced soot emission under all operating range compared with high speed direct injection (HSDI) mode. Finally, this paper presents the boosted LTC map of emission and the strategy of improved engine operating range.

• Fire Science and Engineering
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• v.27 no.4
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• pp.56-60
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• 2013

The aim of study intends to investigate physiological changes according to workload wearing aluminized firefighter's protective clothing and to provide the base data for the safety of firefighter. The results of the study are as follows. To increase work intensity 4 to 8 METs after experiment (20 min), mean skin temperature change (33.3 %), tympanic temperature change (57.1 %) heart rate (32.5 %), RPE (75.6 %) is statistically significantly higher and thermal Sensation, weight loss are not statistically significant. It was concluded that physiological changes of human body varied considerably by increase of workload wearing aluminized firefighter's protective clothing.

• Journal of the Korean Ceramic Society
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• v.35 no.11
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• pp.1190-1196
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• 1998

Ultrafine ${\beta}$-SiC powders were synthesized by the vapor phase reaction of TMS[Si(CH3)4] in hydrogen The reaction temperature and TMS concentration were varied from 1000 to 1400$^{\circ}C$ and from 1 to 10% respectively. The average particle size and phase of the powders were analyzed by TEM and XRD. Ultrafine ${\beta}$-SiC powders were synthesized above 1000$^{\circ}C$ and the crystallinity of the powders increased with increasing reaction temperature. Shape of the particles were spherical and had average size of about 20 nm which showed no difference as the reaction temperature and TMS concentration increased. From the FT-IR analysis the absorption bands of Si-C of the powders shifted to higher wavenumber as the reaction temperature increased,. Under the condition of total gas flow above 1500cc/min ${\beta}$-SiC and poly-Si powders were obtained simultaneously. The Si-O bond intensity was increased under the condition of total gas flow rate above 1000cc/min which might be due to oxidation formed on poly-Si.

• Journal of the Korean Ceramic Society
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• v.50 no.4
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• pp.280-287
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• 2013

Plate-type phosphor is a promising substitute in overcoming the issues related to the powder phosphor paste mixed with resin. In this research, $Ca-{\alpha}-SiAlON:Eu^{2+}$ plate phosphor ($Ca_xSi_{12-(m+n)}Al_{m+n}O_nN_{16-n}:Eu_y$) was investigated for the varied compositions (m,n) of the host crystal with the fixed Eu content (y). Densification was promoted for the compositions with increasing 'm' values for the m=2n relationship. Dictated by the Eu concentration inside the phosphor crystal, photoluminescence intensity was stronger in ${\alpha}2$ specimen (m = 3.0, n = 1.5) containing the second phases when compared to ${\alpha}1$ specimen (m = 1.5, n = 0.75) comprising a single-phase ${\alpha}$-SiAlON. The concentration of Eu in the non-emitting amorphous interfacial glass phase was 2~4 times of the designed Eu concentration inside the ${\alpha}$-SiAlON crystal.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.24 no.9
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• pp.718-722
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• 2011

In this work, we investigated to the etching characteristics of the TiN thin film in He/$BCl_3/Cl_2$ plasma. The etch rate was measured by the gas mixing ratio, the RF power, the DC bias voltage and the process pressure. The maximum etch rate in He/$BCl_3/Cl_2$ plasma was 59 nm/min. The etch rate increased as the RF power and the DC-bias voltage was increased. The chemical reaction on the surface of the etched the TiN thin films was investigated with X-ray photoelectron spectroscopy (XPS). The intensity of Ti 2p and N 1s peaks are varied during etching process. A new peak was appeared in He/$BCl_3/Cl_2$ plasma. The new peak was revealed Ti-$Cl_x$ by Cl 2p peak of XPS wild scan spectra analysis.

• Journal of the Korean Society of Combustion
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• v.9 no.3
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• pp.10-18
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• 2004

An experimental study of the effect of operating conditions on the behavior of a lean premixed laboratory combustor operating on natural gas has been conducted. Measurements were made characterizing the pressure fluctuations in the combustor and the flame structure over a range of inlet temperatures, inlet velocities and equivalence ratios. In addition the fuel distribution at the inlet to the combustor was varied such that it was an independent parameter in the experiment. Inlet temperature, inlet velocity and equivalence ratio were all found to have an effect on the stability characteristics of the combustor. The nature of this effect, however, depended on the fuel distribution. For example, with one fuel distribution the combustor would become unstable when the temperature was increased, whereas with a different fuel distribution the combustor would become unstable when the temperature was decreased. Similarly, the operating conditions had an effect on the flame structure. For example the intensity-weighted center of mass of the flame was found to move closer to the center body as either the temperature or equivalence ratio increased. It was interesting and somewhat surprising to note, however, that as the location of the center of mass changed with operating conditions it did so by moving along a line of constant flame angle.