• Journal of the Korean Applied Science and Technology
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• v.13 no.3
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• pp.145-153
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• 1996

Naphthoquinone-1,2-diazide-5-sulfonyl[NDAS] derivatives members of quinone diazide compound that are utilizable as photosensitive polymer material were synthesized, and photoresist were prepared by mixing these derivatives with m-cresol novolak(a matrix resin) at various weight ratios. Photosensitive characteristics of photoresist were studied by examining UV and IR, relative sensitivity using a Gray scale method, and SEM to analyze if they can be used as photosensitive material in printing process. Experimental results showed that, by UV, NDAS derivatives were photoconverted and developer-soluble photoresist were produced. The mixing ratio of 1:4(by mass) of NDAS+p-ydroxybenzophenone+sensitizer and m-cresol novolak gave rise to the highest dissolution rate. In addition, photoresist obtained at this condition resulted in the most superior sensitivity and contrast.

• 한국연소학회:학술대회논문집
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• 2004.06a
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• pp.102-111
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• 2004

Partial quenching structure of turbulent diffusion flames in a turbulent mixing layer is investigated by the method of flame hole dynamics to develope a prediction model for the turbulent lift off. The present study is specifically aimed to remedy the problem of the stiff transition of the conditioned partial burning probability across the crossover condition by adopting level-set method which describes propagating or retreating flame front with specified propagation speed. In light of the level-set simulations with two model problems for the propagation speed, the stabilizing conditions for a turbulent lifted flame are suggested. The flame hole dynamics combined with level-set method yields a temporally evolving turbulent extinction process and its partial quenching characteristics is compared with the results of the previous model employing the flame-hole random walk mapping. The probability to encounter reacting' state, conditioned with scalar dissipation rate, demonstrated that the conditional probability has a rather gradual transition across the crossover scalar dissipation rate in contrast to the stiff transition of resulted from the flame-hole random walk mapping and could be attributed to the finite response of the flame edge propagation.

• 한국연소학회:학술대회논문집
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• 2007.05a
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• pp.176-183
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• 2007

An experimental study was performed to investigate the effects of mixing quality, inlet pressure, nozzle diameter on CO emission and radiation characteristics in porous ceramic fiber radiant burners. Observations of combustion characteristics occurring inside the burner system which was insulated fiber mat, were investigated by measuring temperature, CO emission and radiation characteristics. Combustion was achieved at the firing rate of $88{\sim}99$ kcal/hr, inlet pressure of $100{\sim}250$mm$H_2O$. CO emissions were found to be strongly dependent on the operating conditions. There was a tendency that CO concentration increased as the firing rate increases. The reason for rise of CO concentration is that it becomes the relatively rich condition. The fiber burner exhibit significant both spectral intensity peaks in the bands at 2.5${\mu}m$ and 4.0${\mu}m$ relatively, There is a small difference in the variable mixing tube. However spectral intensity increased with the firing rate.

• Transactions on Electrical and Electronic Materials
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• v.10 no.5
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• pp.147-151
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• 2009

For integrated passive device (IPD) applications, we have successfully developed and characterized metalinsulator-metal (MIM) capacitors with 2000 $\AA$ plasma-enhanced chemical vapor deposition (PECVD) silicon nitride which are deposited with the $SiH_4/NH_3$ gas mixing rate, working pressure, and RF power of PECVD at $250^{\circ}C$. Five PECVD process parameters are designed to lower the refractive index and lower the deposition rate of $Si_3N_4$ films for the high breakdown electric field. For the PECVD process condition of gas mixing rate (0.957), working pressure (0.9 Torr), and RF power (60 W), the atomic force microscopy (AFM) root mean square (RMS) value of about 2000 $\AA$ $Si_3N_4$ on the bottom metal is lowest at 0.862 nm and the breakdown electric field is highest at about 8.0 MV/cm with a capacitance density of 326.5 pF/$mm^2$. A pretreatment of metal electrodes is proposed, which can reduce the peeling of nitride in the harsh test environment of heat, pressure, and humidity.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.05b
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• pp.585-588
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• 2006

The environment-friendly building material, photocatalyst/scoria/loess concrete, was prepared using scoria and loess (which have merits as building materials) and photocatalyst (which has the functions to compose the environmental contaminants and of self cleaning). In order to apply this material as a building material, the compressive and flexible strengths, and water absorptivity (which have been set by Korea Industrial Standard) were measured. The optimum mixing ratio of photocatalyst/scoria/loess concrete was obtained at the condition of $393kg/m^3$ of coarse aggregate, $802kg/m^3$ of fine aggregate in case of scoria, $80kg/m^3$ of loess, $12kg/m^3$ of photocatalyst, $400kg/m^3$ of cement, and $2kg/m^3$ of AE water reducing agent. The photocatalyst/scoria/loess concrete prepared by above mixing ratio of raw materials showed 25 MPa of compressive strength, $3.8{\sim}4.6$ MPa of flexible strength and $11.4{\sim}12.0%$ of water absorptivity, indicating that the quality of this material was suitable for Korea Industrial Standard (more than 21 MPa for compressive strength, more than 2.0 MPa for flexible strength in case of lightweight aggregate, and less than 15 % for water absorptivity in case of clay brick) for using as a building material.

• Fibers and Polymers
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• v.1 no.1
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• pp.32-36
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• 2000

An alternative strategy to .educe the percolation threshold of carbon black (CB) in polymer blends was investigated using random copolymer ternary blends of polystyrene (PS), poly(methyl methacrylate)(PMMA), and a styrene-methyl methacrylate random copolymer (SMMA). The target morphology was to selectively locate CB particles in the encapsulating layer of SMMA during melt mixing. The CB used in this study is BP-2000 from Cabot and has a strong selective affinity to PS. Even when the CB was premixed with SMMA, it moves to the PS phase during the melt mixing. However, we also observed the CB particles located at the interface between SMMA and PS phases. Through this study it is found that the interaction between polymers and CB particles is critical for selectively localizing CB particles in multi-component polymer blends. Although appropriate processing condition may retard the movement of CB particles to the polymer phase with affinity, it cannot prevent it completely and locate them to the SMMA phase, which is not thermodynamically favored. To locate CB particles in an encapsulating layer of ternary polymer blends, first of all, polymers forming it should have selective affinity to CB.

• Journal of Environmental Science International
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• v.20 no.6
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• pp.767-773
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• 2011

The objectives of this research are to investigate the proper coagulation conditions which are a type and doses of coagulants, mixing conditions (velocity gradients and mixing times), pH and so on through Jar-test, to evaluate the flux variations, permeate, backwashing according to characteristics of pretreatment of the wastewater by means of MF membranes for river maintenance water reuse. The effluent water from B-city K-sewage treatment plant are used for this research. Turbidity and suspended solids(SS) are 14.2 NTU and 10.4 mg/L respectively. This condition causes fouling for membrane process. The flux decline could be reduced when coagulation pretreatment was carried out. Optimal coagulations PAC which are commonly used in the sewage treatment plant was observed in this research. The results indicate that an optimal coagulation dose and pH are 80 ppm and pH of 7 respectively, but coagulation efficiency was lower at strong acid or strong base. Results showed that continuous and steady operations in membrane separation process by means of the effective removal of organic matter and turbidity with coagulation pretreatment of sewage secondary effluent were achieved.

• Aerospace Engineering and Technology
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• v.3 no.2
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• pp.183-190
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• 2004

The performance analysis of a fuel pump for a liquid rocket engine has been performed numerically on its design condition. A commercial three-dimensional Navier-Stokes flow solver has been used for the computation. All of the fuel pump components - inducer, impeller, volute and secondary flow passages - are included in computation for the accurate estimation of the leakage flow rate which affects the performance and axial thrust. A pitchwise-averaged mixing plane method was used on the boundaries among the fuel pump components to save computational time. The predicted overall performance satisfied the design requirement. However, the axial thrust exceeded a permissible limit. In order to reduce the axial thrust, the secondary flow passage design has been changed. With this change, the axial thrust level has been reduced to 30% as compared with the original value.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.30 no.11 s.254
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• pp.1093-1100
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• 2006

Combustion stability rating of jet injector is conducted numerically using air-injection technique in a model chamber, where air is supplied to oxidizer and fuel manifolds of the model five-element injector head. A sample F(fuel)-O(oxidizer)-O-F impinging-jet injector is adopted. In this technique, we can simulate mixing process of streams flowing through oxidizer and fuel orifices under cold-flow condition without chemical reaction. The model chamber was designed based on the methodologies proposed in the previous work regarding geometrical dimensions and operating conditions. From numerical data, unstable regions can be identified and they are compared with those from air-injection acoustic and hot-fire tests. The present stability boundaries are in a good agreement with experimental results. The proposed numerical method can be applied cost-effectively to stability rating of jet injectors when mixing of fuel and oxidizer jets is the dominant process in instability triggering.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.1154-1157
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• 2003

The spent fuel slitting device is an equipment developed for the separation of the pellet and hull from the cutting fuel rod with length of 250 mm, and in order to feed UO$_2$ pellet. We have analyzed on the existing technologies for designing and producing of the slitting device in the first year(2001), based on these results, designed and produced the rod slitting device. It has effectively separated the pellet from the hull, but demanded the supplement separation work because of the mixing with pellet and hull in the vessel, and required the condition for the reducing time of the process. In the second year(2002), we have reduced the work time, performed the test and capacity evaluation with the improving device, based these results, and ensured the data demanded for designing of the spent fuel rod slitting device. We have compared with the DUPIC(Direct use of spent PWR fuel in CAND reactors) process, and developed the device for the purpose of reducing over 40 % in comparition with the DUPIC operation time(5 minutes). Based on these results, it will is effectively applied to available data for designing and producing of the hot test facility.