• 한국압력기기공학회 논문집
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• 제5권2호
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• pp.35-39
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• 2009

In this study, Event Type Analysis System (ETAS) is developed for the accident evaluation in nuclear power plant. The ETAS system can be used in supporting regulator and/or operator under event situation in nuclear power plants. The ETAS system can categorize the all transient events to 3 categories such as Down-2000, Down-2173, and Slow Fluctuation. We develop the program structure for ETAS system and web-based ETAS system. The ETAS system will be used as sub module of Knowledge-Based Event Evaluation Network (K-EvENT) which is developing for the against the accident in nuclear power plants.

• 한국전산유체공학회지
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• 제7권4호
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• pp.19-27
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• 2002

An efficient implicit multigrid method is presented for the Navier-Stokes and k-ω turbulence equations. Freezing and limiting strategies are applied to improve the robustness and convergence of the multigrid method. The eddy viscosity and strongly nonlinear production terms of turbulence are frozen in the coarser grids by passing down the values without update of them. The turbulence equations together with the Navier-Stokes equations, however, are consecutively solved on the coarser grids in a loosely coupled fashion. A simple limit for k is also introduced to circumvent slow-down of convergence. Numerical results for the unseparated and separated transonic airfoil flows show that all computations converge well without any robustness problem and the computing time is reduced to a factor of about 3 by the present multigrid method.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2002년도 학술대회지
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• pp.31-34
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• 2002

An efficient implicit multigrid method is presented for the Navier-Stokes and $k-{\omega}$ turbulence equations. Freezing and limiting strategies are applied to improve the robustness and convergence of the multigrid method. The eddy viscosity and strongly nonlinear production terms of turbulence are frozen in the coarser grids by passing down the values without update of them. The turbulence equations together with the Navier-Stokes equations, however, are consecutively solved on the coarser grids in a loosely coupled fashion. A simple limit for k is also introduced to circumvent slow-down of convergence. Numerical results for the unseparated and separated transonic airfoil flows show that all computations converge well without any robustness problem and the computing time is reduced to a factor of about 3 by the present multigrid method.

• Geomechanics and Engineering
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• 제36권4호
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• pp.391-406
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• 2024

In order to study the soil seasonal dynamic characteristics in the regions with four distinct seasons, the soil dynamic triaxial experiments were conducted by considering the environmental temperature range from -30℃ to 30℃. The results demonstrate that the dynamic soil properties in four seasons can change greatly. Firstly, the dynamic triaxial experiments were performed to obtain the dynamic stress-strain curve, elastic modulus, and damping ratio of soil, under different confining pressures and temperatures. Then, the experiments also obtain the dynamic cohesion and internal friction angle of the clay under the initial strain, and the changing rule was summarized. Finally, the results show that the dynamic elastic modulus and dynamic cohesion will increase significantly when the clay is frozen; as the temperature continues to decrease, this increasing trend will gradually slow down, and the dynamic damping ratio will go down when the freezing temperature decreases. In this paper, the change mechanism is objectively analyzed, which verifies the reliability of the conclusions obtained from the experiment.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2011년도 제42회 하계학술대회
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• pp.2109-2109
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• 2011

High power microwave sources operating in relativistic regions, high current reletivistic electron beams are obtained by using cold cathodes with the help of explosive emission. For these relativistic devices, the pulsed power and magnetic field systems are very large and heavy. The phase velocity of electromagnetic mode should be showed down close to the beam velocity, ensuring enough beam coupling with electromagnetic modes. By using the annular electron beam, a weakly relativistic oversized bwo consisting of rectangularly corrugated cylindrical waveguide is demonstrated.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2006년도 6th International Meeting on Information Display
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• pp.1034-1037
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• 2006

We have developed a novel thin film encapsulation method for thin-cathode OLED by introducing organic (not polymer)/inorganic multiple thin films to protect device, which is shown to slow down the permeation rate of moisture and oxygen. From the stability test of devices, the projected lifetime of thin-cathode OLED device with thin film encapsulation was similarly to that with glass lid encapsulation.

• 한국자기공명학회논문지
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• 제26권4호
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• pp.66-70
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• 2022

Protein structure determination using NMR spectroscopy requires a suite of heteronuclear 3-D NMR experiments that can take a couple of weeks for completion. During the experiments, protein samples may suffer from slow degradation due to co-purifying proteases, which complicates and slows down the assignment procedure. Here we describe a practical protocol to avoid unwanted proteolysis during the experiment.

• 한국초지조사료학회지
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• 제8권2호
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• pp.104-109
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• 1988

A field experiment was conducted in order to investigate the seasonal changes of leaf grwoth and related characteristics in three cultivars of orchardgrass; Potomac, Kay and Sumas. The results were summarized as follows: 1. Leaf elongation was increased in a nearly linear phase during first and third cutting stages. It was increased slowly in early 10 days to 15 days after cutting and increased rapidly there-after during the rest cutting stages. In cultivars, Potomac was showed higher leaf elongation than other cultivars during all cutting stages. There was no difference of leaf width within cutting stages, but the leaf width of fall regrwoth was narrow. Sumas had relatively short and wide leaves. 2. Leaf dry weight and leaf area in first cutting stage were larger than others. Leaf area was increased rapidly form 15 days after cutting and leaf weight was increased rapidly from 20 days over all cutting stages. The increase in leaf area and dry weight were slow down after 30 days. 3. Number of epidermal cells was increased rapidly after cutting and the rate of increase was slow down after 30 days. In a cross section of leaf tissue, the part of mesophyll was occupied with about 60% of total area and larger area than other tissue, the part of mesophyll was occupied with about 60% of total area and larger area than other tissues. Leaf tissue had a large vacancy at early growth period after harvest and was filled gradually with mesophyll. This result was related to the increase of leaf dry matter.

• Elastomers and Composites
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• 제14권2호
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• pp.83-102
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• 1979

The purpose of this dissertation is to study some of the vulcanization characteristics of rubber-bound antioxidants such as G-1, [N-(3-methacryloyloxy-2-hydroxypropyl)-N'-phenyl-p-phenylene diamine] and acryl, acrylamide & acrylester substituted hindered phenols. The influence of these antioxidants upon vulcanization characteristics in NR and SBR compounds in the presence of vulcanizing accelerators such as MSA, TT, DM, M & D was evaluated by means of Oscillationg Disk Cure Meter. The comparison was also made between the influence of rubber-bound antioxidants and that of conventional non-reactive antioxidants such as N-alkyl substituted PADA series. Regarding the influence of reactive type antioxidant G-1 mixed with accelerator TT upon vulcanization characteristics, rapid onset of vulcanization and higher degree of cross-linking were discovered, whereas in the case of accelerator M and DM, the result was slow onset of vulcanization and lesser degree of cross-linking. The comparison of vulcanizing characteristics among acrylic substituted hindered phenols as antioxidants was made under several vulcanization accelerator systems. Under such systems, MSA-S combined accelerator caused the onset of vulcanization to slow down and lowered the degree of cross-linking. Finally in the case of hindered phenol derivatives containing longer substituent, the delayed onset of vulcanization and the lowered degree of cross-linking could be discerned.

• 천문학회지
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• 제11권1호
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• pp.1-30
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• 1978

The four dimensional classification of globular dusters with the parameters, Z, Y, age and HB type is presented defining two new parameters. $(B-V)_{1/2}\;and\;S_{3/2}$ which are shown to be tightly correlated with Kinman's spectral types and the helium abundances obtained from the R-method, respectively. The Z- and Y- abundances are derived from $(B-V)_{1/2}\;and\;S_{3/2}$, respectively, and the latter parameters determine the age class of clusters with help of Dickens' HB type, which is a function of Z. Y and age. For the examined forty two globular clusters the computed range at Z and Y are $1.5{\times}10^{-4}{\leq}Z{\leq}4.5{\times}10^{-2}\;and\;0.23<Y{\leq}0.41$. The age difference between the oldest (HB type 1) and the youngest (HB type 7) clusters is roughly estimated to be $2-4{\times}10^9$ years. Using these four parameters the known anomalous C-M diagrams seem to be reasonably interpreted without taking into account some complicate parameters such as unusually overabundant heavy elements, mass loss and mass spread, etc. The four dimensional scheme strongly suggests the slow successive collapses of the proto-Galaxy rather than a single fast collapse, and by this slow collapse model the inversion of chemical abundance gradient in the Galaxy can be explained. It is also shown that the clump position along the RGB near the HB level removes down to the fainter magnitude as the Z(Y)- abundance increases (decreases).