• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2008.05a
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• pp.125-128
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• 2008

Atomization characteristics of small LRE-injector spray are investigated by using dual-mode phase Doppler anemometry (DPDA). Velocity, size, number density, and volume flux were measured at various injection pressures along the radial distance to make a close inquiry into spatial distribution characteristic of spray droplets. As the injection pressure increases, the velocity, turbulence intensity, number density, and volume flux of spray droplets become higher, whereas the droplet size ($D_{10}$ or $D_{32}$) gets smaller. Also, velocity and volume flux are proportional to Sauter mean diameter (SMD, $D_{32}$).

• Transactions of Materials Processing
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• v.11 no.5
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• pp.447-456
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• 2002

A study has been made to investigate the boundary sliding and its accommodation mode with respect to the variation of $\alpha$$_2$/$eta$ volume fraction during superplastic deformation of two-phase Ti$_3$Al-xNb intermetallics. Step strain rate and load relaxation tests have been performed at 950, 970 and 99$0^{\circ}C$ to obtain the flow stress curves and to analyze the deformation characteristics by the theory of inelastic deformation. The results show that the grain matrix deformation and boundary sliding of the three intermetallics containing 21, 50 and 77% in $eta$ volume fractions are well described by the plastic deformation and viscous flow equations. Due to the equal accommodation of both $a^2$ and $\beta$ phases, the accommodation modes for fine-grained materials are in good agreement with the iso-strain rate models. The sliding resistance analyzed for the different boundaries is the lowest in the $\alpha$$_2$/$\alpha$$_2$ boundary, and increases in the order of $\alpha$$_2$/$\alpha$$_2$<< $\alpha$$_2$/$\beta$ = $\beta$/$\beta$, which plays an important role in controlling the superplasticity of the alloys with the various $\alpha$$_2$/$\beta$ phase ratio.

• Journal of Mechanical Science and Technology
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• v.14 no.3
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• pp.306-313
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• 2000

The homogenization method and the density function method are common approaches to evaluate the equivalent material properties for design cells composed of matter and void. In this research, using a new topology optimization method based on the homogenized material with a penalty factor and the chessboard prevention strategy, we obtain the optimal layout of a structure for the natural frequency of a designated mode. The volume fraction of nodes of each finite element is chosen as the design variable and a total material usage constraint is imposed. In this paper, the subspace method is used to evaluate the eigenvalue and its corresponding eigenvector of the structure for the designated mode and the recursive quadratic programming algorithm, PLBA algorithm, is used to solve the topology optimization problem.

• Journal of Sensor Science and Technology
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• v.16 no.4
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• pp.254-258
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• 2007

A novel cure sensor based on the side-polished single mode fiber has been proposed and demonstrated. Two different UV curable epoxies were used to verify the feasibility of the side-polished single mode fiber as a high sensitivity cure sensor. The volume change of the epoxy by UV curing results in a corresponding change of the refractive index. The sensor can be used to monitor the curing process, the refractive index variation and the volume change of epoxy in real time during the UV curing process. In addition, small birefringence of the epoxy film can be detected using the sensor.

• The Journal of Korean Society for Radiation Therapy
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• v.25 no.2
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• pp.153-158
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• 2013

Purpose: After making two plans, the Double Scattering (DS) Mode and The Pencil Beam Scanning (PBS) Mode, of patients on early prostate cancer, we not only compare the dose conformity and the dose homogeneity by analyzing each DVH, CN and HI, but also evaluate normal structures's sparing effect on each mode. Materials and Methods: Planes about nine patients, who did proton therapy, on prostate cancer was setted using the Eclipse proton external beam planning system. The prescription dose, every $2.5 Gy{\times}28$ fractions=70 Gy, was delivered to the PTV. The CN and the HI were getted by anlazing each DVHs for the DS Plan and the PBS Plan. Also, normal structures' %volumes according to dose of the PBS are campared with those of the DS. Results: The average CN of the PTV is increase 16.63% from DS $0.68{\pm}0.07$ to PBS $0.79{\pm}0.01$, and the average IN of the PTV is decrease -22.66 % from DS $0.12{\pm}0.03$ to PBS $0.09{\pm}0.01$. The PBS has litter %Volumes of normal structures than the DS about every patient except Rectum. The average %Volume of Left Femoral Head receiving ${\geq}30$ Gy shows most high decreasing rate, -79.93%, from DS to PBS and the average %Volume of Rectum receiving ${\geq}70$ Gy shows most low decreasing rate, -3.03%, from DS to PBS. Conclusion: Therefore, the PBS is more effective achieving the dose conformity and the dose Homogeneity than DS, and better to reduce unnecessary dose arriving normal structures, especially the femoral heads.

• Journal of the Korean Society of Propulsion Engineers
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• v.21 no.6
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• pp.21-31
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• 2017

In the present study, theoretical and numerical analyses have been carried out to investigate the detailed flow characteristics during the mode transition. The theoretical analysis rearranged the knowledge of gasdynamics and the previous studies, and the numerical analysis has conducted to solve the 2D unsteady compressible Navier-Stokes equations with a fully implicit finite volume scheme. To validate the numerical analysis, the experiment was compared with it. The total temperature at the inlet of isolator and the hydrogen fuel equivalent ratio were changed to investigate their effects on the mode transition phenomenon. As the results, the numerical analysis reproduced well the experiment qualitatively, the increment in the hydrogen fuel equivalent ratio induced the scram-mode to ram-mode transition which is discontinuous with a non-allowable region, and the variation in the total temperature changed the boundary of the mode transition.

• Fisheries and Aquatic Sciences
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• v.13 no.4
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• pp.308-314
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• 2010

Larvae of Palaemon serrifer were reared in the laboratory under three different temperature regimes ($15^{\circ}C$, $20^{\circ}C$, $25^{\circ}C$) to study the effects of rearing temperature on larval survival and growth, as well as other traits such as embryo volume, number of embryos (fecundity), incubation period, development. Mode and development period. Growth pattern was analyzed by measuring the molt increment and intermolt period. The intermolt period consistently increased with size and instar number and was shortest at $25^{\circ}C$. However, molt increments generally decreased with instar number. Number of embryos varied from 552 to 1355. The relationship between the number of embryos and carapace length was expressed by the equation (fecundity) y=2.7744x+0.208 ($R^2$=0.7961). Egg volume was a primary factor affecting other life-history traits. Egg volume was $0.078\;m^3$, which is relatively small thus embryos exhibited a relatively short incubation period and a comparatively short development period, and the nutritional mode was planktotrophic. Brood production was followed by a fast parturitional pattern. Most ovigerous females had mature ovaries when the parturial molt occurred soon after eclosion.

• Nuclear Engineering and Technology
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• v.38 no.4
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• pp.343-352
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• 2006

Convenient analytical tools for evaluation of the aperiodic and the fluctuating instabilities of the passive residual heat removal system (PRHRS) of an integral reactor are developed and results are discussed from the viewpoint of the system design. First, a static model for the aperiodic instability using the system hydraulic loss relation and the downcomer feedwater heating equations is developed. The calculated hydraulic relation between the pressure drop and the feedwater flow rate shows that several static states can exist with various numbers of water-mode feedwater module pipes. It is shown that the most probable state can exist by basic physical reasoning, that there is no flow rate through the steam-mode feedwater module pipes. Second, a dynamic model for the fluctuating instability due to steam generation retardation in the steam generator and the dynamic interaction of two compressible volumes, that is, the steam volume of the main steam pipe lines and the gas volume of the compensating tank is formulated and the D-decomposition method is applied after linearization of the governing equations. The results show that the PRHRS becomes stabilized with a smaller volume compensating tank, a larger volume steam space and higher hydraulic resistance of the path $a_{ct}$. Increasing the operating steam pressure has a stabilizing effect. The analytical model and the results obtained from this study will be utilized for PRHRS performance improvement.

• Proceedings of the KSR Conference
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• 2011.10a
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• pp.2917-2920
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• 2011

This study aim at demonstrating the environmental performance of freight transport of the rail and road mode through an indicator of embodied energy and $CO_2$ emissions. Using the concept of LCA, the scope of evaluation includes energy production, supply chain activity and operation. The results of embodied energy and $CO_2$ emissions are normalized by means of traffic volume. The results shown that embodied $CO_2$ emissions road mode is 607.07 $gCO_2-eq./tkm$ and 284.67 $gCO_2-eq./tkm$ for road and rail mode, respectively. This number reveals that road mode is 2.1 times larger than rail mode. The results also indicate that the main contribution of $CO_2$ emission from road mode is in the operation stage, which accounts for 70%; however, it is the construction and supply chain stage that accounts for over 50% of the emission of rail mode.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.32 no.11
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• pp.404-416
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• 1983

This paper is concerned with the design automation of the sequential machines. The operations of sequential machine can be diveded into two types such as synchronous and asynchronous sequential machine and their realization is treated in separate mode. But, in order to integrate logic circuits in high volume, mixed mode sequential machine uses common circuitry that consists of gates and flip-flops. Proposed sequential machine can be designed by several method, which are hard-wired implementation, firmware realization by PLA and ROM. And then onr example shows the differnces among three design mothods. Finally, computer algorithm(called MINIPLA) is discussed for various application of mixed-mode sequential machine.