• Journal of The Geomorphological Association of Korea
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• v.18 no.3
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• pp.21-36
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• 2011

Rock Weathering is a basic of geomorphological evolution as a preparation of materials. Of those, frost shattering has traditionally been considered as the operative process causing rock breakdown in cold regions as well as temperate zone. Each Granite(fresh rock, semi-weathered), Gneiss, Limestone, Dolomite was prepared slab specimens in ten, repeated freeze-thaw cycles of 180 under the -25℃~+30℃, and the changes was observed in physical properties and weathering aspect. Rock shattering was more active in waterlogging conditions rather than atmospheric and soil conditions. Limestone and Dolomite that high porosity are most severely crushed. Gneiss, regardless surface of the crack, joint, fissure and has a lowest rock strength(SHV), was even though no physical changes and their weathering product do not generate, has a very high resistance to weathering.

• Journal of the Korean Society of Systems Engineering
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• v.20 no.1
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• pp.85-94
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• 2024

As systems become more complex today, verifying the safety of complex systems is becoming increasingly important. However, validation activities using actual systems face limitations in terms of time and cost. To overcome these limitations, the functions, characteristics, and operations of physical assets can be implemented in a virtual environment similar to the real world, allowing for validation through simulations under various scenarios. By performing validation in a virtual environment, iterative tests can be conducted through simulations in a realistic virtual environment without physical models during the conceptual design phase. Tests can also be performed under malfunction conditions or extreme conditions. In this study, we introduce a verification method for railway vehicles in a virtual environment and propose a method of applying virtual verification from a life cycle perspective.

• Nuclear Engineering and Technology
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• v.56 no.9
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• pp.3491-3500
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• 2024

In this work, the hybrid vibro-acoustic model reduction technique that is a physical-modal combined formulation is proposed to accelerate the finite element model updating process of the vibro-acoustic pipeline system. Particularly, the new formulation could provide an effective way of the model updating by preserving the physical DOFs for the direct calibration of the undetermined boundary conditions. The sensitivity based vibro-acoustic model updating is first conducted, and then the undetermined spring constant at the displacement boundary condition is then directly and effectively calibrated by using the proposed hybrid model reduction formulation. The proposed method is implemented in the real nuclear facility to evaluate its performance. In addition, an experimental implementation test using the inverse force identification process is also conducted to demonstrate the reliability of the generated vibro-acoustic FE model through the proposed method.

• Journal of the Society of Naval Architects of Korea
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• v.49 no.2
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• pp.146-150
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• 2012

Free vibrations of strings due to initial conditions have been analyzed by the conventional mode summation method, and the nondimensionalized displacements and velocities have been derived in the form of infinite series. The results show wave propagating phenomena and confirmed by experiments using the high speed camera. Other physical characteristics have been discussed and examined with help of waveform solutions.

• Pediatric Gastroenterology, Hepatology & Nutrition
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• v.16 no.4
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• pp.219-224
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• 2013

Acute abdominal pain is a common complaint in childhood, and it can be caused by a wide range of underlying surgical and non-surgical conditions. The most common non-surgical condition is gastroenteritis, while the most common surgical condition is appendicitis. Abdominal pain in children varies with age, associated symptoms, and pain location. Although acute abdominal pain is usually benign and self-limiting, there are uncommon but life-threatening conditions that require urgent care. Meticulous history taking and physical examinations are essential to determine the cause of acute abdominal pain and to identify children with surgical conditions such as appendicitis.

• Proceedings of the Korean Vacuum Society Conference
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• 2015.08a
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• pp.249.1-249.1
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• 2015

Quantum dots (QDs) are attracting growing attention for photovoltaic device applications because of their unique electronic, optical and physical properties. Lead sulfide (PbS) QDs are one of the most widely studied materials for the devices and known to have size-tunable properties. In this context, we investigated the relationship between the size of PbS QDs and two synthesizing conditions, a concentration of ligand, oleic acid in this work, and injection temperature. The inverted colloidal quantum dot solar cells based on the heterojunction of n-type zinc oxide layer and p-type PbS QDs were also fabricated. The size of the QDs and cell properties were observed to depend on both the QD synthesizing conditions, and hence the overall efficiency of the cell could vary even though the size of QDs used was same. The QD synthesizing conditions were finally optimized for the maximum cell efficiency.

• 한국석유지질학회:학술대회논문집
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• spring
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• pp.56-65
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• 1998

Methane hydrate is ice-like solid compound consisting of mainly methane and water, and is stable under specific low temperature and high pressure conditions (HSZ : methane hydrate stability zone) that occurs in permafrost regions and in the ocean floor sediments. Geophysical survey was implemented in the southern area of the East Sea, and the HSZ of the study area is determined by the temperature, pressure and local heat flow obtained from the survey and well data. In the study area, methane hydrates could exist in the sediments below the water depths of about $300{\cal}m$, and the base of HSZ is about 600m beneath the seafloor. The acoustically blanking zones in the sediment and phenomena of gas seepage were detected from the seismic section. These sediments have the sufficient physical condition for the formation of methane hydrate. The temperature and pressure conditions were experimentally measured for the dissociation of methane and propane hydrates in Pure water. Equilibrium conditions of methane and propane hydrates were obtained in the pressure range up to 19050Kpa and 401.3Kpa. Under same temperature condition, propane hydrate was dissociated at lower pressure than that of methane hydrate.

• International Journal of Automotive Technology
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• v.2 no.3
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• pp.103-107
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• 2001

Many researches on pressure-swirl injectors due to the variety of application have been conducted on the effects of nozzle design, operating conditions, properties of liquid and ambient conditions on the flow and spray characteristics. The breakup length of conical emulsified fuel sheet resulting from pressure-swirl atomizer using in the oil burner was investigated with the digital image processing method with neat light oil and emulsion with water content of lotto% and the surfactant content of 1-3%. The injection pressure ranged from 0.1 to 1.2 MPa was selected. The various regimes for the stage of spray development within the experimental conditions selected in this study is newly suggested in terms of Ohnesorge number and injection pressure. The breakup length for both criteria show the same tendency even though the random nature of perforation and disintegration process of liquid sheet. The stage of spray development is widely different with the physical properties of liquid atomized, mainly viscosity of liquid. The breakup length decreases smoothly with increase in the injection pressure for the lower viscous liquid.

• Journal of Biosystems Engineering
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• v.21 no.3
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• pp.357-371
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• 1996

An assessment of the field performance of machines for varied farming conditions may be essential to the development of mechanization program and rational machinery management. The field performance of machines is largely affected by the field capacity of machinery selected, physical size and shape of field plots and their scatterness, farming functions and conditions, and labor requirement and constraints. The study was to develop the mathematical model for the field performance of machines and time requirement of the rice farming systems, considering those factors which affect the field performance of machines. The mathematical models developed were simulated to determine field efficiency and capacity of the different sizes of major machinery for a various size of paddy field plot and for prevailing conditions of farming operations. The effects of the sises of machinery and the plot geometry on the efficiency and field capacity were compared for major rice farming functions.

• 한국신재생에너지학회:학술대회논문집
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• 2011.05a
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• pp.74.2-74.2
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• 2011

A simulation study on synthesis gas process in GTL process was carried out in order to find optimum operation conditions for GTL (gas-to-liquid) pilot plant design. Optimum operating conditions for synthesis gas process were determined by changing reaction variables such as feed temperature and pressure. During the simulation, overall synthesis process was assumed to proceed under steady-state conditions. It was also assumed that physical properties of reaction medium were governed by RKS (Redlich-Kwong-Soave) equation. The effect of temperature and pressure on synthesis gas process $H_2$/CO ratio were mainly examined. Simulation results were also compared to experimental results to confirm the reliability of simulation model. Simulation results were reasonably well matched with experimental results.