• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.05a
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• pp.131-134
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• 2005

PDP 방전 셀의 최적화 및 진공자외선 발광효율을 향상시키기 위한 목적으로 AC - PDP 미소방전에서 제논 여기종 원자의 밀도를 측정하는 레이저 흡수법을 개발하였다. 본 연구에서는 PDP 셀의 기체 압력을 350Torr, 제논 함량 10%로 고정하고, 전극 위에서의 여러 위치에서 준안정 준위 제논의 밀도를 흡수법으로 측정하였다. 실험 결과 제논 여기종의 밀도의 최대값은 전극의 위치(가장자리에서 안쪽으로의 거리)가 $50{\mu}m$, $120{\mu},\;150{\mu}m$ 일 때 $3.5{\times}10^{12}cm^{-3}$, $2.8{\times}10^{12}cm^{-3}$, $2.2{\times}10^{12}cm^{-3}$로 나타났다.

• Korean Journal of Soil Science and Fertilizer
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• v.44 no.3
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• pp.387-393
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• 2011

We analyzed the particle size distributions of three commercially available Devarda's alloy (DA) products, tested the nitrate recoveries of each particle size category, and examined the amounts of DA required for 100% recovery by varying $NO_3$-N concentration from 0.5 to 10 mg. We observed that use of DA coarser than 200 mesh resulted in poor analytical recovery (<80%). While the tested alloys were considered to be fine enough (>90% of the particles were less than 100 mesh), the recovery dramatically declined from 80% to 10% in a high concentration range (4 to 10 mg N). Satisfactory recovery was obtained by increasing the amount of finer DA (less than 300 or 450 mesh). However, there was no quantitative relationship between the amount of fine DA and nitrate recovered. Generally, the amount of nitrate reduced per unit DA decreased as the recovery efficiency declined. These results suggest that a sufficient amount of DA must be determined based on particle size distribution, and that treatment of at least two levels of DA and comparison of the subsequent change in nitrate recovery is required for soils containing high levels of nitrate. In addition, further studies are encouraged to account for the observed stoichiometric dis-equivalence of recovered nitrate N per unit mass of DA.

• Journal of the Korean Magnetics Society
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• v.6 no.1
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• pp.28-35
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• 1996

Dispersion behavior was investigated as functions of species and arrount of addtives, binders, abrasives, lubricants, etc.. Dispersibilityand other various properties were affected by the fuctional groups of binders. Friction coefficient and surface roughness of tape were changed with lubricants, therefore duratility of magnetic tape was varied. As a result of above investigations, we concluded that dispersion behavior of particles was very sensitive for obtaining maximum properties of metal particle tape.

• 한국연소학회:학술대회논문집
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• 2014.11a
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• pp.75-76
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• 2014

The present study has numerically investigated the effects of the oxidizer-side nitrogen dilution on the precise structure and NOx formation characteristics of the turbulent syngas nonpremixed flames. Eulerian particle flamelet model was used to predicted the NOx formation characteristics in the turbulent syngas swirling nonpremixed flames. Current numerical simulation was conducted for the syngas gas turbine combustor. Numericla results indicate that as the H2O portion is increased in diluent, the formation of NOx decreased effectively in turbulent syngas swirl nonpremixed flames.

• Journal of the Korean Ceramic Society
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• v.27 no.2
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• pp.265-273
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• 1990

Fine Si-Al-OH-C coprecipitate powders were prepared from Si(OC2H5)4, Al(i-OC3H7)3, and carbon black by a hydrolysis method before fabrication of Sialon-SiC composite powder by carbothermal reduction at 1350$^{\circ}C$ for 10h under N2/H2 mixed atmosphere. The characterization of the synthesized Sialon-SiC composite powders was performed using XRD, BET, SEM, TEM and particle size analysis methods. The average particle size and specific surface area of the synthesized Sialon-SiC composite powder were 0.13$\mu\textrm{m}$ and 20.1㎡/g, respectively when Z=1 and N2 : H2=50 : 50.

• Smart Structures and Systems
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• v.19 no.4
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• pp.351-360
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• 2017

Protection of structures against natural hazards such as earthquakes has always been a major concern. Semi-active control combines the reliability of passive control and versatility and adaptability of active control. So it has recently become a preferred control method. This paper proposes an algorithm based on Uniform Deformation Theory to mitigate vulnerable buildings using magneto-rheological (MR) damper. Due to the successful performance of fuzzy logic in control of systems and its simplicity and intrinsically robustness, it is used here to regulate MR dampers. The particle swarm optimization (PSO) algorithm is also used as an adaptive method to develop a fuzzy control algorithm that is able to create uniform inter-story drifts. Results show that the proposed algorithm exhibited a desirable performance in reducing both linear and nonlinear seismic responses of structures. Performance of the presented method is indicated in compare with passive-on and passive-off control algorithms.

• Journal of the Korean Society for Heat Treatment
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• v.15 no.2
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• pp.82-92
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• 2002

In the present investigation wear behavior of the 6061AI composites reinforced with 5, 10, 20% SiC particles for dry sliding against a SM45C counterface was studied as a function of load and sliding velocity. Sliding wear tests were conducted at two loads(19.6 and 49N) and three sliding velocities(0.2, 1 and 2 m/sec) at constant sliding distance of 4000 m using pin-on-disk machine under room temperature. Presence of SiC reinforcement particles in the composites has displayed a transition from mild to severe wear at relatively higher applied load and sliding velocity compare to that of the matrix metal. As the volume fraction of SiC particles increased, the transition moved to a more severe wear conditions. Eventually, mild wear prevailed at a most severe wear conditions in this study, that was 49N load and 2 m/sec sliding velocity in 20% SiC particle/6061AI composite.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.16 no.1
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• pp.70-76
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• 2003

For the development of superconducting power apparatus, it is necessary to establish the dielectric technology in coolant like L$N_2$. Therefore in this paper we conducted experiment of surface flashover that could occur in the windings of HTS transformer which will be developed in the pancake coil type. First, we distinguished two types of surface flashover by electrode alignment, such as parallel and vertical, and then compared with each characteristics of surface flashover. The flashover voltage was more affected by thickness of spacer than by surface length when the thickness of spacer is over 1 mm. And the surface flashover with metallic particle attached on the spacer was tested, it was affected by the particle position. The more close to the electrodes, the worse the characteristics. Also the experiment was conducted when the electrode was immersed in liquid nitrogen(L$N_2$) partially. The surface flashover characteristics of spacer was, when immersed partially in 50%, rapidly decreased.

• Proceedings of the KSR Conference
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• 2004.10a
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• pp.704-709
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• 2004

The wear behavior and the mechanical property of Cu-$TiB_2$ composites were examined. Cu-$TiB_2$ composites were fabricated by hot extrusion and cold drawing with $TiB_2$ contents(1$\∼$5vol.$\%$) and the size of $TiB_2$ particles(10$\mu$m and 20$\mu$m). The pin-an-disk wear test was carried out under dry sliding wear conditions which loads varied with from 20N to 100N. At the time, counterpart wear material used SM45C. The experimental results showed that the friction coefficient and wear rate decreased with increasing the $TiB_2$ contents and decreasing the size of $TiB_2$ particle. Also, the depth of plastically deformed zone decreased with increasing the $TiB_2$ contents and decreasing the size of $TiB_2$ particle.

• Journal of the Korean Ceramic Society
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• v.37 no.1
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• pp.44-49
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• 2000

Silicon nitride powders, were synthesized by the vapor phase reaction using SiH4-NH3 gaseous mixture. The reaction temperature, ratio of NH3 to SiH4 gas and the overall gas quantity were varied. The synthesized powders were characterized using X-ray, TEM, FT-IR and EA. The synthesized silicon nitride powders were in amorphous state, and the average particle size was about 100nm. TEM analysis revealed that the particle size decreased with increasing reaction temperature and gas flow quantity. As-received amorphous powders were annealed in nitrogen atmosphere at 140$0^{\circ}C$ for 2h, then the powders were completely crystallized at 0.2 ratio of NH3 to SiH4.