• Journal of the Korean Society of Combustion
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• v.7 no.3
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• pp.47-54
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• 2002

The propagation speed of tribrachial flame in laminar propane jets has been investigated experimentally under normal and micro gravity conditions. The displacement speed was found to vary nonlinearly with axial distance because flow velocity along stoichiometric contour was comparable to the propagation speed of tribrachial flame for the present experiment. Approximate solutions for velocity and concentration accounting density difference and virtual origins have been used in determining the propagation speeds of tribrachial flame. Under micro gravity condition, the results showed that propagation speed of tribrachial flame is largely affected by the mixture fraction gradients, in agreement with previous studies. The limiting maximum value. of propagation speeds under micro gravity conditions are in good agreement with the theoretical prediction, that is, the ratio of maximum propagation speed to the stoichiometric laminar burning velocity is proportional to the square root of the density ratio of unburned to burnt mixture.

• Journal of Positioning, Navigation, and Timing
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• v.10 no.1
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• pp.55-66
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• 2021

In this paper, we propose a signal propagation modeling technique for generating a positioning fingerprint DB based on Long Term Evolution (LTE) signals. When a DB is created based on the location-based signal information collected in an urban area, gaps in the DB due to uncollected areas occur. The spatial interpolation method for filling the gaps has limitations. In addition, the existing gap filling technique through signal propagation modeling does not reflect the signal attenuation characteristics according to directions occurring in urban areas by considering only the signal attenuation characteristics according to distance. To solve this problem, this paper proposes a Deep Neural Network (DNN)-based signal propagation functionalization technique that considers distance and direction together. To verify the performance of this technique, an experiment was conducted in Seocho-gu, Seoul. Based on the acquired signals, signal propagation characteristics were modeled for each method, and Root Mean Squared Errors (RMSE) was calculated using the verification data to perform comparative analysis. As a result, it was shown that the proposed technique is improved by about 4.284 dBm compared to the existing signal propagation model. Through this, it can be confirmed that the DNN-based signal propagation model proposed in this paper is excellent in performance, and it is expected that the positioning performance will be improved based on the fingerprint DB generated through it.

• Nuclear Engineering and Technology
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• v.55 no.12
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• pp.4408-4425
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• 2023

Alarm flood due to abnormality propagation is the most difficult alarm overloading problem in nuclear power plants (NPPs). Root-cause analysis is suggested to help operators in understand emergency events and plant status. Multilevel Flow Modeling (MFM) has been extensively applied in alarm management by virtue of the capability of explaining causal dependencies among alarms. However, there has never been a technique that can identify the actual root cause for complex alarm situations. This paper presents an automated root-cause analysis system based on MFM. The causal reasoning algorithm is first applied to identify several possible root causes that can lead to massive alarms. A novel root-cause ranking algorithm can subsequently be used to isolate the most likely faults from the other root-cause candidates. The proposed method is validated on a pressurized water reactor (PWR) simulator at HAMMLAB. The results show that the actual root cause is accurately identified for every tested operating scenario. The automation of root-cause identification and ranking affords the opportunity of real-time alarm analysis. It is believed that the study can further improve the situation awareness of operators in the alarm flooding situation.

• Journal of Ginseng Research
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• v.9 no.1
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• pp.42-53
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• 1985

This study was carried out to obtain the basic information about the large scale propagation of ginseng (Panax ginseng C.A. Meyer). Therefore, the stem cuttings of 1-year old ginseng, treated with various concentrations of plant growth regulators for 5 seconds (quick dipping) and 24 hours (prolonged soaking), were cultured. The root formation of stem cuttings was varied with the concentrations, kinds, and treatment methods of plant growth regulators. Besides normal-looking roots various malformed roots were observed. In the prolonged soaking method, the culture of stem cuttings, treated with 10 ppm of IBA or NAA, resulted in profuse root regeneration. And stem cuttings, in quick dipping method, treated with 2000 ppm of IBA or NAA resulted in more excellent root regeneration. In general, IBA was more vigorous for the root formation than NAA, The treatment with 50 ppm kinetin or 100 ppm BA brought good result for the retardation of senescence of stem cuttings and BA treatment was more effective than kinetin. As for the saponin content of roots derived from stem cutting culture, the roots, formed by non-treatment of growth regulators, were higher in saponin content than those formed by treatment of growth regulators.

• Journal of Ship and Ocean Technology
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• v.9 no.1
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• pp.64-71
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• 2005

In probabilistic design, the challenge is to estimate the uncertainty propagation, since outputs of subsystems at lower levels could constitute inputs of other systems or at higher levels of the multilevel systems. Three uncertainty propagation estimation techniques are compared in this paper in terms of numerical efficiency and accuracy: root sum square (linearization), distribution-based moment approximation, and Taguchi-based integration. When applied to reliability-based design optimization (RBDO) under uncertainty, it is investigated which type of applications each method is best suitable for. Two nonlinear analytical examples and one vehicle crashworthiness for side-impact simulation example are employed to investigate the unique features of the presented techniques for uncertainty propagation. This study aims at helping potential users to identify appropriate techniques for their applications in the multilevel design.

• Proceedings of the KSME Conference
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• 2004.04a
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• pp.302-307
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• 2004

This paper reviewed characteristics of fatigue crack behavior observed by changing various shapes of initial crack and magnitudes of loading in compact tension shear(CTS) specimen subjected to shear loading. In the high-loading condition, fatigue crack under shear loading propagated branching from the pre-crack tip. Meanwhile, the secondary fatigue crack in the low-loading condition which was created in the notch root due to friction on the pre-crack face grew to a main crack. Influenced by the mode II loading condition, fatigue crack propagation retardation appeared in the initial propagation region due to the reduction of crack driving force and friction on crack face. In both cases, however, fatigue cracks grew in tensile mode type. Propagation path of fatigue crack under the shear loading was 70 degree angle from the initial crack regardless of its shape and load magnitude.

• Korean Journal of Plant Resources
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• v.13 no.2
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• pp.140-146
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• 2000

This study was conducted to determine the effect of cutting type, growth regulators and propagation media on the rooting and root growth of Roea davurica $P_{ALL}$. Three type of cutting, hardwood, half-softwood, softwood cutting and root cutting of Rosa davurica $P_{ALL}$, were used to study the rooting ability. There was no rooting in hardwood cutting while root cutting was appeared 100% of callus formation and rooting. The optimum conditions of softwood cutting for rooting were IAA 100ppm and rooton-F at vermiculite+perlite. The rate of rooting in treatment of rooton-F ranged from 10 to 60%, but such a good effect was not appeared in other growth regulators, IAA, NAA and IBA.

• Horticultural Science & Technology
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• v.33 no.4
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• pp.511-517
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• 2015

This research was conducted to evaluate the influence of root restriction materials and media on the growth of runner plantlets of 'Seolhyang' strawberry in a nursery field. To achieve this, the influence of three kinds of root media on the growth of runner plantlets was monitored when polyethylene film was used as the root restriction material. In addition, the influence of various root restriction materials (RRS) such as transparent polyethylene film (PE), non-woven fabric (NF), perforated polyethylene film (PP), and root proofing sheet (RPS) on the changes in volumetric water content (VWC) and temperature of root media as well as growth of runner plantlet were investigated when expanded rice hull (ERH) was used as the root medium. In the comparison of root media, growth parameters such as leaf area and crown thickness at 20 d after fixation as well as crown thickness and fresh weights of root and above-ground tissue at 40 d after runner plantlet fixation were higher in the ERH treatment than in sandy loam and loamy sand. When the influence of RRS was compared, the VWC of ERH was 55% just after irrigation, but decreased to 26% at just before irrigation. Ranges of the VWC as influenced by irrigation cycle were 16 to 10% in the PP and less than 10% in the NF and RPS. The soil temperature in the PE treatment was around $1^{\circ}C$ lower than in NF, PP, and RPS. The differences between day and night temperatures were also smaller in the PE treatment rather than those in NF, PP, and RPS. The growths of runner plantlet 50 d after fixation showed that plant heights as well as fresh weights of root and above-ground tissue were higher in the PE treatment than in NF, PP, and RPS. NF and PP did not effectively restrict roots inside the medium and the roots of runner plantlets penetrated through the root restriction materials resulting in the formation of root system below the restriction materials. The above results indicate that ERH is more effective than sandy loam or loamy sand as root medium. PE rather than NF, PP, or RPS as root restriction material resulted in better growth of runner plantlets in propagation of 'Seolhyang' strawberry. The results of this research will be used for production of high quality runner plantlets in strawberry propagation.

• Korean Journal of Plant Resources
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• v.35 no.6
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• pp.770-777
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• 2022

The main objective of this study was to identify the most appropriate condition for root formation of in vitro micropropagated pear (Pyrus spp.) plants. In vitro propagation was induced on Murashige and Skoog (MS) medium with 2.0 mg/L of N6-benzyladenine (BA) and 0.2 mg/L of Indole-3-butyric acid (IBA) medium. The short pre-treatment of explants with a high concentration (1 mg/L) of NAA and IBA (R0 medium) in dark for three days, followed by transfer to five different media (R1 to R5) resulted in good rooting responses in the pear 'Oharabani (P. pyrifolia × P. communis)' genotype. For the rooting experiments, the highest rooting percentage (83.3 ± 8.3%), average root length (3.6 ± 1.9 mm), total root number (31 ± 4.0), and average root number per plant (2.6 ± 2.1) were obtained on half strength (1/2) of MS medium supplemented with 30 g/L sucrose without hormones and activated charcoal (AC) (R1 medium). The highest rooting percentage was obtained at 83.3% from explants on R1 and R3 media. The rooting procedure described in this study resulted in good root formation and significantly shorting the root induction time to within 14 days of culture. Further studies are underway to test the suitability of the protocol developed in this study for other pear genotypes.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.34 no.2
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• pp.113-120
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• 2021

The wave-propagation phenomenon in an infinite medium has been used to describe the physics in many fields of engineering and natural science. Analytical or numerical methods have been developed to obtain solutions to problems related to the wave-propagation phenomenon. Energy radiation into infinite regions must be accurately considered for accurate solutions to these problems; hence, various numerical and mechanical models as well as boundary conditions have been developed. This paper proposes a new boundary condition that can be applied to scalar-wave or horizontally-polarized shear-wave (or SH-wave) propagation problems in layered waveguides. A governing equation is obtained for the SH waves by applying finite-element discretization in the vertical direction of the waveguide and subsequently modified to derive the boundary condition for the infinite region of the waveguide. Using the orthogonality of the eigenmodes for the SH waves in a layered waveguide, the new boundary condition is shown to be equivalent to the existing root-finding absorbing boundary condition; further, the accuracy is shown to increase with the degree of the new boundary condition, and its stability can be proven. The accuracy and stability are then demonstrated by applying the proposed boundary condition to wave-propagation problems in layered waveguides.