• 한국연소학회:학술대회논문집
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• 한국연소학회 1997년도 제15회 KOSCO SYMPOSIUM 논문집
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• pp.23-32
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• 1997

Characteristics of the lifted flame which is generated by issuing of the fuel through the miniature nozzle, d=0.164 mm, are studied using the planar laser induced fluorescence technique. OH radical is excited on the $Q_1$(8) line of the $A^2{\Sigma}\ ^+{\leftarrow}\ X^2{\prod}$ (1,0) band transition(283.55 nm) and LIF signals are captured at the bands of (0,0) and (1,1) transition(306-326 nm) using the filters and ICCD camera. Hydroxyl radical(OH) profile for nozzle attached flame shows that OH radical populations at the flame sides and flame tip are larger than those at the base. But for the lifted flame (tribrachial flame) case, those are larger at the flame base than at the flame tip and flame sides. The OH radical is more dense near the center line of flame base at the blowing out. This fact proves the Chung and Lee's blowout theory - blowout occurs when the flame is anchored at the flame axis.

• 전기학회논문지
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• 제60권12호
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• pp.2206-2214
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• 2011

LDC(Line Drop Compensation) is widely used in controlling ULTC(Under Load Tap Changer) output voltage at distribution substation. However, LDC may experience some difficulties in voltage control due to renewable energy resources and distributed generations. Therefore, more advanced voltage control algorithm is necessary to deal with these problems. In this paper, a modified voltage control algorithm for ULTC and DG is suggested. ULTC is operated with the voltages measured at various points in distribution system and prevents overvoltage and undervoltage in the distribution feeders. Reactive power controller in DG compensates the voltage drop in each distribution feeders. By these algorithms, the voltage unbalance between feeders and voltage limit violation will be reduced and the voltage profile in each feeder will become more flat.

• Tribology and Lubricants
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• 제28권4호
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• pp.153-159
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• 2012

Tapered roller bearings are widely used in high axial-load and radial-load applications. In this study, a numerical analysis is performed to study a finite line contacts EHL problem between a tapered roller and raceway in tapered roller bearings. Converged solutions are obtained for moderate load and material parameters using a finite difference method with non-uniform grids and the Newton-Raphson method. The contours and sectional plots of pressure distribution and film shape are compared. The pressure distribution and film shapes near both ends of the roller are very different from those in the central part and are transversely asymmetric. The maximum pressure and absolute minimum film thickness always occur at the small end of the roller.

• Ocean Systems Engineering
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• 제5권4호
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• pp.319-329
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• 2015

Submerged breakwaters are used to prevent shore line erosion and sediment transportation. One of their advantages is low visual impact. In this paper, the effects of discontinuous submerged breakwaters over water surface elevation was numerically studied considering the extended Boussinesq equations as governing equations using MIKE21 software. The result of discontinuous breakwater was compared with a beach without breakwater. The results showed that the gap dramatically effects on surface elevation from shore line to offshore. It is also evident from results that with approaching the center of the gap, fluctuation of surface elevation is generated. It is because of passing longshore currents towards offshore through the gap which leads to an increase in sediment transportation rate. Nevertheless, transferring water mass from breakwater gap results in powerful rip currents leading to high changes on longshore wave profile.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2010년도 추계 학술발표회
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• pp.546-552
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• 2010

Seasonal frozen ground affects structural behavior in South Korea. Frost and heaving of seasonal frozen ground results in the critical damage of roadway, railroad, and buried pipeline. It has been widely used to substitute frost susceptible soils with granular soils. This paper presents experimental investigation on the effectiveness of soil-shredded tire and soil-expanded polystylene (EPS) mixtures to reduce frost depth and force around a buried pipeline. Experimental data such as measured temperature profile and the deformation of buried pipeline were carefully observed and provide the evidence of the effectiveness of soil mixtures.

• Journal of Microbiology and Biotechnology
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• 제16권8호
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• pp.1292-1300
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• 2006

Aeromonas encheleia, a potential human intestinal pathogen, was shown to infect a human intestinal epithelial cell line (Caco-2) in a noninvasive manner. The transcriptional profile of the Caco-2 cells after infection with the bacteria revealed an upregulated expression of genes involved in chloride secretion, including that of phospholipase A2 (PLA2) and platelet-activating factor (PAF) acetylhydrolase (PAFAH2). This was also confirmed by a real-time RT-PCR analysis. As expected from PLA2 induction, PAF was produced when the Caco-2 cells were infected with the bacteria, and PAF was also produced when the cells were treated with a bacterial culture supernatant including bacterial extracellular proteins, yet lacking lipopolysaccharides. Bacterial aerolysin was shown to induce the production of PAF.

• 한국전기전자재료학회논문지
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• 제18권4호
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• pp.381-385
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• 2005

The plasma temperature of Ar gas in hollow cathode discharge were measured. This is done by measuring the line profile of the 1s/sub 8/-2p/sub 8/ transition in Ar, using a single-frequency diode laser. Low power diode lasers have been successfully used for investigation of the line profiles of Ar transitions in hollow cathode discharges. It turns out that the plasma temperature of Ar is 640∼783 K in the discharge current range at 7∼10 mA.

• International Journal of Control, Automation, and Systems
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• 제5권1호
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• pp.43-50
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• 2007

Reheating furnace is an essential facility of a rod mill plant where a billet is heated to the required rolling temperature so that it can be milled to produce wire. Although it is very important to obtain information on billet temperatures, it is not feasible during furnace operation. Consequently, a billet temperature profile should be estimated. Moreover, this estimation should be done within an appropriate time interval for an on-line application. In this paper, a billet heat transfer model based on 2D FEM(Finite Element Method) with spatially distributed emission factors is proposed for an on-line billet temperature estimation and also a measurement is carried out for two extremely different furnace operation patterns. Finally, the difference between the model outputs and the measurements is minimized by using a new optimization algorithm named uDEAS(Univariate Dynamic Encoding Algorithm for Searches) with multi-step tuning strategy. The obtained emission factors are applied to a simulation for the data which are not used in the model tuning for validation.

• 천문학논총
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• 제15권spc1호
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• pp.127-132
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• 2000

The purposes of spectroscopy in astronomy are to measure the radiation flux of the spectroscopic emission or absorption line and to measure the dynamical parameters of the line profile. In order to use an appropriate instrument for the scientific purpose, we need to understand the characteristics of various spectrometers, e.g., a prism spectrometer, a grating spectrometer, and a Fabry-Perot spectrometer (FPS), which are being used in ultra-violet, optical, and infrared bands. The Fabry­Perot spectrometer is not very popular compared to the grating spectrometer, because of its complex and tricky operations. The Fabry-Perot spectrometer, however, can get a two-dimensional image at one exposure, so we can study radiation mechanisms and dynamical properties of extended sources, e.g., clusters, nebula, and galaxies.

• 천문학회보
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• 제41권2호
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• pp.35.2-35.2
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• 2016

Lyman alpha photons emitted from the early generation galaxies are scattered through the intergalactic medium, and can be observed as Lyman alpha emitting sources. We examine the Lyman alpha line transfer mechanism by tracing the random scattering histories of Lyman alpha photons in the intergalactic medium of the early universe. The density and ionization fields are based on the 3D map by N-body + radiation transfer simulations of the epoch of reionization. The calculation is compared with analytical models, too. The emergent line profile and the size of the Lyman alpha blob are strongly tied to the density and ionization environment, likely to give constraints when high-z Lyman alpha blobs are observed.