• Journal of Advanced Marine Engineering and Technology
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• v.33 no.7
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• pp.1017-1025
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• 2009

This study intends to study about the blade performance loss occurred due to the variation in the shape of airfoil from the attachment/non-attachment of blade erosion shield for hovercraft. This study model has used NACA 4412, has designed NACA 4412 by using Auto CAD and designed the shape that has attached an erosion shield to this model according to the thickness and length. By using these models, we have generated a grid by using GAMBIT and calculated the lift coefficient (Cl) and drag coefficient (Cd) by using the FLUENT code for flow analysis. Through this, we have calculated and compared the lift-to-drag ratio that is an indicator of airfoil performance according to the shape and attachment/non-attachment of erosion shield.

• Proceedings of the Korea Concrete Institute Conference
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• 2003.05a
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• pp.985-990
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• 2003

In order to demonstrate Advanced Spent Fuel Conditioning Process (ACP), shielding facilities such as hot cell suitable to handling radionuclides and process property will be necessary. But the construction of new facilities needs much money, man-power and time, it is now scheduled to remodel the hot cell, which has already been installed and maintained at Irradiated Material Experiment Facility (IMEF) in the Korea Atomic Energy Research Institute (KAERI). The basic structure and concrete shield wall of hot cell partly have been constructed on the base floor in IMEF building in current status. And hot cell after remodeling will be used for carrying out the lab-scale experiment of ACP. The hot cell was built in accordance with 35 curies of fe-59(1.2 MeV) as design criteria of radiation dose limit. But the radioactive source of ACP is expected to be much higher than design criteria of IMEF, shielding ability of the hot cell in the current status is unsatisfactory to the hot test of ACP. Therefore shield wall shall be reinforced with heavy concrete, steel or lead. In this paper, dose rates are calculated according to ACP source, shielding materials, etc., and reinforcement structures are determined considering the current situation of hot cells, installation of shield windows and the easiness of work.

• Journal of the Korea Convergence Society
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• v.8 no.9
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• pp.211-216
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• 2017

The purpose of this study is to evaluate the usefulness of a newly fusion model designed cloak shield to reduce the radiation exposure of the assistant during CT(computed tomography) of severely injured patient. Radiation dose was measured in the heart, both axillary and thyroid areas using newly designed cloak shield and existing shield with head phantom and human phantom under the same conditions as brain vascular CT scan. The newly designed cloak shield was measured higher for radiation shielding rate than the existing shields, 61.9 % for heart, 46.2 % for left axillary, 69.8 % for right axillary and 71.1 % for thyroid gland, respectively. a newly developed fusion model of cloak shields are useful for reducing radiation exposure. It is expected to make a significant contribution to reduction of radiation exposure.

• Journal of Korean Society for Atmospheric Environment
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• v.8 no.2
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• pp.93-99
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• 1992

Recently a passive $NO_2$ samplers have been frequently used for the measurement of $NO_2$ concentration in the atmosphere because of its simplicity and high accuracy. But these samplers have a defect that the amount of $NO_2$ adsorbed is increased by wind. In this study, the inlet of sampler was covered with a draft shield made by 325 mesh stainless sieve to eliminate the effect. But it was expected that $NO_2$ diffusion was interrupted by the draft shield. In order to conform this phenomenon, samplers with and without draft shield were exposed to a box filled with 1-1.1ppm $NO_2$. The result indicated that draft shield nearly did not disturb $NO_2$ diffusion. To protect samplers from dust, sunshine, precipitation and vertical wind effects, these samplers were placed into a shelter during the field test. The data obtained in this study was compared with the data from the ambient air monitoring network. The coefficient of correlation(r) between the two data was 0.9995 for the test period of up to 35days. The results of this study indicate that the type of $NO_2$ samplers with draft shield in shelter used in this study can be used for measuring $NO_2$ concentrations in the ambient air relatively for a long period over 30 days.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.19 no.1
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• pp.123-132
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• 2021

Radiological impact analyses were carried out for a near-surface radioactive waste repository at Gyeongju in South Korea. The RESRAD-ONSITE code was applied for the estimation of maximum exposure doses by considering various exposure pathways based on a land area of 2,500 ㎡ with a 0.15 m thick contamination zone. Typical influencing input parameters such as shield depth, shield materials' density, and shield erosion rate were examined for a sensitivity analysis. Then both residential farmer and industrial worker scenarios were used for the estimation of maximum exposure doses depending on exposure duration. The radiation dose evaluation results showed that 60Co, 137Cs, and 63Ni were major contributors to the total exposure dose compared with other radionuclides. Furthermore, the total exposure dose from ingestion (plant, meat, and milk) of the contaminated plants was more significant than those assessed for inhalation, with maximum values of 5.5×10-4 mSv·yr-1 for the plant ingestion. Thus the results of this study can be applied for determining near-surface radioactive waste repository conditions and providing quantitative analysis methods using RESRAD-ONSITE code for the safety assessment of disposing radioactive materials including decommissioning wastes to protect human health and the environment.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.2
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• pp.554-560
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• 2013

This study proposes an structure that fixes the shielding device to two parts of the board by its two arranged clips. Said structure evenly distributes its loading/unloading load of the board and maintains the flatness of soldering area of the board. The structure of this study comprises a base part fixed to a printed circuit board and a clip part fixing a side wall of a shield can to the board, wherein the clip part is constituted with two clips fixable to two part of the shield can. Also, the structure of this study comprises a dented groove in order to easily solder the base part of clips and the printed circuit board. A mechanism is established and a design parameter was determined by a structure analysis and a vibration mode analysis. A single purpose machine for the production of the product was developed, the final workpiece was produced and the measuring-data and the computered-data was compared and reviewed.

• Journal of the Korean Society for Railway
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• v.16 no.1
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• pp.47-51
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• 2013

In this study, we carried out an experimental shield TBM excavation model test using a down-scale device in soft clay, to understand tunnel-face stability properties in relation to changes in slurry pressure. We performed five tests according to tunnel depth (0.5D, 0.75D, 1.0D, 1.25D, 1.5D), and compared theoretical tunnel-face pressure with model test results. The range in theoretical tunnel-face slurry pressure ($P_{min}{\leq}P_{slurry\;pressure}{\leq}P_{max}$), which is determined by earth pressure and water level, was very similar to the model test result. This result was due to the more isotropic condition of the soft clay ground, than of rocky ground.

• Economic and Environmental Geology
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• v.57 no.1
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• pp.25-39
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• 2024

The Téra manganese deposit represents the most significant manganese mineralization discovered in Niger up today. The main host rocks of this ore are gondites, which are a garnet and quartz rich metamorphic rocks. The supergene weathering developed an alteration profile on these gondites. This study aims to identify the mineralogical composition of gondites and associated rocks, in order to highlight the origine of rocks and the manganese enrichment. The methodological approach adopted involved a field study followed by polarizing microscopic analysis using transmitted and reflected lights. Additionally, quantitative X-ray diffraction (XRD) analysis was performed to assess the manganese ore minerals present in the gondite and associated rocks, including mica schists, amphibolites, and quartzites. The petrographic study revealed a paragenesis characterized by the presence of kyanite, staurolites, garnets and plagioclases that are generally poikiloblasts with quartz and opaque minerals inclusions, emphasizing the internal schistosity which is planar, helicitic or microfolded. These features indicate a prograde metamorphism until high-pressure amphibolite facies conditions. These conditions are followed by greenschist facies conditions marked by calcite, epidote, muscovite, chlorite and muscovite assemblage which emphasizes the vertical tectonics. Depending on the alteration process, the manganese ore exhibit a granular texture at the bottom of the gondite hills, transitioning to a colloform texture towards the top, passing through the epigenization and replacement texture. The XRD analysis further revealed that the studied rocks originated from a volcano-sedimentary complex, characterized by alternating marly, arenaceous and pelitic sequences associated with submarine exhalations.

• Journal of Cerebrovascular and Endovascular Neurosurgery
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• v.25 no.4
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• pp.452-461
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• 2023

The Anterior Inferior Cerebellar Artery-Posterior Inferior Cerebellar Artery (AICA-PICA) common trunk is a rare variant of cerebral posterior circulation in which a single vessel originating from either the basilar or vertebral arteries supplies both cerebellum and brainstem territories. We present the first case of an unruptured right AICA-PICA aneurysm treated with flow diversion using a Shield-enhanced pipeline endovascular device (PED, VANTAGE Embolization Device with Shield Technology, Medtronic, Canada). We expand on this anatomic variant and review the relevant literature. A 39-year-old man presented to our treatment center with vertigo and right hypoacusis. The initial head CT/CTA was negative, but a 4-month follow-up MRI revealed a 9 mm fusiform dissecting aneurysm of the right AICA. The patient underwent a repeat head CTA and cerebral angiogram, which demonstrated the presence of an aneurysm on the proximal portion of an AICA-PICA anatomical variant. This was treated with an endovascular approach that included flow diversion via a PED equipped with Shield Technology. The patient's post-procedure period was uneventful, and he was discharged home after two days with an intact neurological status. The patient is still asymptomatic after a 7-month follow-up, with MR angiogram evidence of stable aneurysm obliteration and no ischemic lesions. Aneurysms of the AICA-PICA common trunk variants have a high morbidity risk due to the importance and extent of the territory vascularized by a single vessel. Endovascular treatment with flow diversion proved to be both safe and effective in obliterating unruptured cases.

• Explosives and Blasting
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• v.28 no.1
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• pp.40-54
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• 2010

The messer shield method applys mainly to a tunnel with small cross-section of a weathered soil or weathered rock district and is fulfilled mostly by man-power excavation. but in case that hard rock exposes on tunnel face, incredible is an application of the rock-splitting method using a hydraulic power or a blasting method. This study represents the case of a blasting method which can control to be practiced by the minimum charges of 125 g an initial vibration occurring at the cut instead of the rock-splitting method, even though water pipe and gas pipe are closely adjacent.