• Journal of Magnetics
• /
• v.18 no.3
• /
• pp.308-310
• /
• 2013

Translation induced by the field-gradient force is being observed for a single ferromagnetic iron grain and a ferrimagnetic grain of a ferrite sample ($CuFe_2O_4$). From measurements on the translation, precise saturated magnetization of $M_S$ is possible for a single grain. The method is based on the energy conservation rule assumed for the grain during its translation and the grain is translated through a diffuse area under microgravity conditions. The results of the two materials indicate that a field-induced translation of grain bearing spontaneous moment is generally determined by a field-induced potential $-mM_SH(x)$ where m denotes the mass of sample. According to the above translations, the detection of $M_S$ is not interfered by any signals from the sample holder. The $M_S$ measurement does not require m value. By observing translations resulting from fieldinduced volume forces, the magnetization of a single grain is measurable irrespective of its size; the principle is also applicable to measuring susceptibility of diamagnetic and paramagnetic materials.

• Journal of the Korean Society of Propulsion Engineers
• /
• v.23 no.2
• /
• pp.38-45
• /
• 2019

The present work suggests a numerical approach using a thermoacoustic network model for the eigenvalue calculation of thermoacoustic instability problems in an aero gas turbine combustor. The model is developed based on the conservation laws for mass, momentum, and energy between acoustic network elements with an area change. Acoustic field in a practical aero gas turbine combustor which has a complicated flow path is analyzed using the current model. The predictive capabilities of the current modeling approach are compared with the acoustic characteristics calculated using Helmholtz solver based on 3D finite element method(FEM).

• Nuclear Engineering and Technology
• /
• v.53 no.2
• /
• pp.455-465
• /
• 2021

The Molten Salt Reactor (MSR), one of the six advanced reactor types of the 4th generation nuclear energy systems, has many impressive features including economic advantages, inherent safety and nuclear non-proliferation. This paper introduces a system analysis code named TREND, which is developed and used for the steady and transient simulation of MSRs. The TREND code calculates the distributions of pressure, velocity and temperature of single-phase flows by solving the conservation equations of mass, momentum and energy, along with a fluid state equation. Heat structures coupled with the fluid dynamics model is sufficient to meet the demands of modeling MSR system-level thermal-hydraulics. The core power is based on the point reactor neutron kinetics model calculated by the typical Runge-Kutta method. An incremental PID controller is inserted to adjust the operation behaviors. The verification and validation of the TREND code have been carried out in two aspects: detailed code-to-code comparison with established thermal-hydraulic system codes such as RELAP5, and validation with the experimental data from MSRE and the CIET facility (the University of California, Berkeley's Compact Integral Effects Test facility).The results indicate that TREND can be used in analyzing the transient behaviors of MSRs and will be improved by validating with more experimental results with the support of SINAP.

• Journal of Plant Biotechnology
• /
• v.47 no.4
• /
• pp.273-282
• /
• 2020

In Vietnam, Celastrus hindsii Benth, a medicinal plant rich in secondary metabolites, has been used to alleviate distress caused by ulcers, tumors, and inflammation for generations. The occurrence of two phenotypes, Broad Leaf (BL) and Narrow Leaf (NL), has raised questions about the selection of appropriate varieties for conservation and crop improvement to enhance medicinal properties. This study examined molecular differences in C. hindsii by comparing protein profiles between the NL and BL types using 2D-PAGE and MS. Peptide sequences and proteins were identified by matching MS data against the MSPnr100 databases and verified using the MultiIdent tool on ExPASy and the Blast2GO software. Our results revealed notable variations in protein abundance between the NL and BL proteomes. Selected proteins were confidently identified from 12 protein spots, thereby highlighting the molecular variation between NL and BL proteomes. Upregulated proteins in BL were found to be associated with flavonoid and amino acid biosynthesis as well as nuclease metabolism, which probably attributed to the intraspecific variations. Several bioactive proteins identified in this study can have applications in cancer therapeutics. Therefore, the BL phenotype characterized by healthier external morphological features has higher levels of bioactive compounds and could be better suited for medicinal use.

• Journal of Korean Society of Water and Wastewater
• /
• v.36 no.4
• /
• pp.219-228
• /
• 2022

In this study, we propose a flow velocity evaluation scheme based on pressure measurement in pressurized pipeline systems. Conservation of mass and momentum equations can be decomposed into mean and perturbation of pressure head and flowrate, which provide the pressure head and flowrate relationship between upstream and donwstream point in pressurized pipeline system. The inverse impedance formulations were derived to address measured pressure at downstream to evaluation of flow velocity or pressure at any point of system. The convolution of response function to pressure head in downstream valve provides the flow velocity response in any point of the simple pipeline system. Simulation comparison between traditional method of characteristics and the proposed method provide good agreements between two distinct approaches.

• Journal of the Society of Naval Architects of Korea
• /
• v.60 no.3
• /
• pp.193-201
• /
• 2023

A developed code based on the unified conservation laws of incompressible/compressible fluids is applied to analyze similarity in pressure oscillations caused by pulsating air pockets in sloshing tanks. It is shown that the nondimensional time histories of pressure show good agreements under Froude and geometric similarities, provided that there are no pulsating entrapped air pockets. However, the nondimesional period of pressure oscillation due to the pulsating air pocket becomes longer as the size of the sloshing tank increases. The discrepancy in the nondimensional period is attributed to the compressibility bias of the entrapped air. To get rid of the compressibility bias, the ullage pressure in a sloshing tank is adjusted based on the Bagnold's impact number. The variation in the period of pressure oscillation according to the ullage pressure is explained based on the spring-mass system. It is shown that the nondimensional period of pressure oscillation is virtually constant when the ullage pressure is adjusted based on the Bagnold's impact number, regardless of tank size. It is found that the Bagold's impact number should be the same, if the time history of pressure is important while an entrapped air pocket pulsates.

• Computers and Concrete
• /
• v.32 no.1
• /
• pp.45-60
• /
• 2023

Concrete in water environment is easily subjected to the attack of leaching, which causes its mechanical reduction and durability deterioration, and the key to improving the leaching resistance of concrete is to increase the compaction of its microstructure formed by the curing. This paper performs a numerical investigation on the intrinsic relationship between microstructures formed by the hydration of cement and slag and leaching resistance of concrete in water environment. Firstly, a shrinking-core hydration model of blended cement and slag is presented, in which the interaction of hydration process of cement and slag is considered and the microstructure composition is characterized by the hydration products, solution composition and pore structure. Secondly, based on Fick's law and mass conservation law, a leaching model of hardened paste is proposed, in which the multi-species ionic diffusion equation and modified Gérard model are established, and the model is numerically solved by applying the finite difference method. Finally, two models are combined by microstructure composition to form an integrated curing-leaching model, and it is used to investigate the relationship between microstructure composition and leaching resistance of slag-blended cement pastes.

• Journal of Korean Society of Water and Wastewater
• /
• v.37 no.6
• /
• pp.437-446
• /
• 2023

We propose a transient evaluation scheme using a pressure measurement in a complicate pipeline systems. Conservation of mass and momentum equations in time domain can be transformed into a pressure head and flowrate relationship between upstream and downstream point in frequency domain. The impedance formulations were derived to address measured pressure at downstream to evaluate of flowrate or pressure head at any point of system. Both branched pipeline element and looped pipeline element can be generally addressed in the platform of the basic reservoir pipeline valve system. The convolution of time domain response function with measured pressure head from a downstream point provides flowrate or pressure head response in any point of the designated pipeline system. The proposed method was validated through comparison between traditional method of characteristics and the proposed method in several hypothetical systems.

• Proceedings of the National Institute of Ecology of the Republic of Korea
• /
• v.2 no.4
• /
• pp.229-234
• /
• 2021

Iris dichotoma Pall. found on Daechung Island in Korea has been designated as an endangered species. To aid in conservation efforts of this species, this study investigated its germination characteristics and seed dormancy type. Four sets of seeds were incubated at different temperatures (4/1℃, 15/6℃, 20/10℃, and 25/15℃). One set of seeds was cold stratified (4 weeks at 4/1℃). The final germination rate and mean germination time showed that the optimal germination temperature was 25/15℃. Final germination rates were ~70%, showing no significant difference among temperature treatments. However, mean germination time were significantly different among all temperature treatments except for 4/1℃. Mean germination time for seeds with temperature treatments of 15/6℃, 20/10℃, and 25/15℃ were 3.2, 2.1, and 1.5 weeks, respectively. At 25/15℃, the mean germination time was half of that at 15/6℃. Seeds of I. dichotoma had fully developed embryos at the time of dispersal. No additional growth of the embryo was observed. Cold stratification did not affect the final germination rate or the mean germination time. This study shows that seeds of I. dichotoma have no physiological or morphological dormancy, unlike other members of the Iris genus known to have seed dormancy that needs a relatively high incubation temperature (≥25/15℃) for mass propagation to occur. These results will be useful for understanding ecophysiological mechanisms related to the species' habitat. They are also useful for mass propagation of I. dichotoma for the purpose of conserving this endangered species.

• Journal of the Korean Geotechnical Society
• /
• v.22 no.11
• /
• pp.55-64
• /
• 2006

It is very Important to predict the damage zone of a rock mass induced by blasting for the excavation of an underground cavity such as a tunnel, as the damage zones incur mechanical and hydraulic instability of the rock mass potentially. Complicated blasting processes that can hinder the proper characterization of the damage zone can be effectively represented by two loading mechanisms. The first mechanism is the dynamic impulsive load-generating stress waves that radiate outwards immediately after detonation. This load creates a crushed annulus along with cracks around the blasthole. The second is the gas pressure that remains for an extended time after detonation. As the gas pressure reopens some arrested cracks and extends these, it contributes to the final structure of the damage zone induced by the blasting. This paper presents a simple method to evaluate the damage zone induced by gas pressure during rock blasting. The damage zone is characterized by analyzing crack propagations from the blasthole. To do this, a model of a blasthole with a number of radial cracks that are equal in length in a homogeneous infinite elastic plane is considered. In this model, crack propagation is simulated through the use of only two conditions: a crack propagation criterion and the mass conservation of the gas. The results show that the stress intensity factor of a crack decreases as the crack propagates from the blasthole, which determines the crack length. In addition, it was found that the blasthole pressure continues to decrease during crack propagation.