• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2006.06b
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• pp.331-336
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• 2006

The rail clamp is the device to prevent that a crane slips along rails due to the wind blast as well as to locate the crane in the set position for loading and unloading containers. The wedge type rail clamp should be designed to consider the structural instability and the durability because it compresses both rail side with large clamping force by the wedge working as the wind speed increases. In this research, there are two methods which are design of experiment and variation technology in used commercial software and shape optimization was performed. The optimum results obtained by the two methods are compared and examined.

• Geomechanics and Engineering
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• v.31 no.3
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• pp.249-263
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• 2022

The specially-shaped Polycrystalline Diamond Compact (PDC) cutter is widely used in drill bit design due to its advantages of high rock cutting efficiency, strong impact resistance and long service life in hard and abrasive formation drilling. A detailed understanding of rock cutting behavior of worn specially-shaped PDC cutter is essential to improve the drilling efficiency and decrease the drilling costs. In this paper, the theoretical models of two new principles (loading performance (LP) and cutting performance (CP)) are derived for evaluating the cutting process of worn specially-shaped cutter, the theoretical models consider the factors, such as cutter geometry, aggressiveness, stress state, working life, and rock cutting efficiency. Besides, the numerical model of heterogeneous granite is developed using finite element method combined with Voronoi tessellation, the LP and CP of 12 kinds of worn specially-shaped PDC (SPDC) cutters are analyzed. The results found that the mechanical specific energy (MSE) of worn cutters first increase and then decrease with increasing the cutting depth, and the MSE increase with the increase of back rake angle except for Conical cutter and Wedge-shaped cutter. From the perspective of CP, the worn PDC cutters are more suitable for the smaller cutting depths, and the back rake angle has little effect on the CP of the specially-shaped worn PDC cutters. Conical cutter, Saddle-shaped cutter and Ellipse-shaped cutter have the highest CP value, while Rhombus-shaped cutter, Convex cutter and Wedge-shaped cutter have the lowest value in selecting cutters. This research leads to an enhanced understanding of rock-breaking mechanisms of worn SPDC cutters, and provides the basis to select of specially-shaped PDC cutters for the specific target formation.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.21 no.5
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• pp.836-841
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• 2012

The repair of road pavement and manhole has been resulted long construction times and traffic jams, environmental pollution from construction wastes, and budget waste due to excessive construction costs. In order to resolve such problems, we have developed the new construction method using C-ring, which can fix and raise the manhole securely. This technology is the method by driving in a wedge after inserting C-ring and expanding it in order to raise manhole to the regular height. This has been approved by the test reports of KOLAS(Korea Laboratory Accreditation Scheme), and was confirmed safety, durability and reliabilty in result. In this paper we approved this technology was able to short working times to around 20% and construction costs to around 50% with compare other construction methods. Also, environmental pollution and civil complaints will be prevented because there will be no longer any noises, vibrations, dust, or construction wastes.

• International Journal of Air-Conditioning and Refrigeration
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• v.11 no.3
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• pp.132-139
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• 2003

The effects of casing shapes on the performance and the interaction between an impeller and a casing in a small-sized centrifugal compressor are investigated. Especially, numerical analyses are conducted for the centrifugal compressor with both a circular casing and a volute one. The optimum design for each element (i.e., impeller, diffuser and casing) is important to develop an efficient and compact compressor using alternative refrigerant as working fluids. Typical rotating speed of the compressor is in the range of 40,000∼45,000 rpm. The impeller has backswept blades due to tip clearance and a vane diffuser has wedge type. In order to predict the flow pattern inside an entire impeller, vaneless diffuser and casing, calculations with multiple frames of reference method between the rotating and stationery parts of the domain are carried out. For computations of compressible turbulent flow fields, the continuity and time-averaged Navier-Stokes equations are employed. To evaluate the performance of two types of casings, the static pressure recovery and loss coefficients are obtained for various flow rates. Also, static pressure distributions around casings are studied for different casing shapes, which are very important to predict the distribution of radial load. The static pressure around the casing and pressure difference between the inlet and outlet of the compressor are measured for the circular casing.

• Journal of Medicine and Life Science
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• v.17 no.1
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• pp.25-28
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• 2020

The prevalence of pulmonary pargonimiasis in Korea has been steadily decreasing due to develop of the public health, and there have been few clinical cases of paragonimiasis infections, especially in pneumothorax. A 22-year-old man referred to emergency department for dyspnea and chest pain. The right lung was totally collapsed on a chest X-ray. We emergently performed a closed thoracostomy with a 28-Fr chest tube. However, the air leak from the chest tube persisted for three days after the closed thoracostomy. A chest computed tomography showed multiple subpleural consolidative nodular lesions and mixed ground-glass attenuation nodules. We potentially suspected a secondary pneumothorax resulting from pulmonary paragonimiasis infection because the patient was a Chinese man who was working at a Korean restaurant. We decided to perform a medical treatment instead of pulmonary wedge resections. The air leak was discontinued three days after the prescription of praziquantel. The patient was discharged nine days after the admission. We suggest that anti-parasitic drugs are very effective in the secondary pneumothorax resulting from paragonimiasis.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.10a
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• pp.1532-1548
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• 2008

The tunnel type spillways is under construction to increasing water reservoir capacity in Dae-am dam. The tunnel outlet was planned to be made after installing slope stabilization system on natural slope there. Generally, the tunnel outlet is made perpendicularly to the slope, but in this case, it had to be made obliquely to the slope for not interrupting flow of river. Because of excavation in condition of natural slope caused to deflecting earth pressure, the outlet couldn't be made. So, artificial ground made with concrete that it was constructed in the outside of tunnel for producing the arching effect which enables to make a outlet. We were planned tunnel excavation was carried out after artificial ground made. Artificial ground made by poor mix concrete of which it was planned that the thickness was at least 3.0m height from outside of tunnel lining and 30cm of height per pouring. Spreading and compaction was planned utilized weight of 15 ton roller machine. In order to access of working truck, slope of artificial ground was designed 1:1.0 and applied 2% slope in upper pert of it for easily drainage of water. In addition to, upper pert of artificial ground was covered with soil, because of impaction of rock fall from upper slope was made minimum. The tunnel excavation of the artificial ground was designed application with special blasting method that it was Super Wedge and control blasting utilized with pre-percussion hole.

• Journal of Korean Society of Forest Science
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• v.113 no.2
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• pp.164-169
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• 2024

In South Korea, most felling operations involve the use of chainsaws due to steep and rough terrains. This felling technique is responsible for approximately 80% of all fatalities mainly due to unpredictable felling directions. Therefore, readjust monitorised felling is imperative to improve safety in different working conditions. This study examined the effect of wedging on felling direction error and productivity during felling operations. When wedging was applied, a felling direction error within 22° and a productivity of 0.63 m³/min were obtained. These results show a decrease in mean directional error and a dimish in productivity. Thus, although wedging reduces productivity, it is a necessary strategy to improve safety.

• The Journal of Korean Society for Radiation Therapy
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• v.16 no.1
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• pp.39-50
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• 2004

This study was carried out to evaluate the effect of general and occupational characteristics musculoskeletal symptoms in Radiological Technologist who working in present department more than 1 year. Standardized questionnaire of NIOSH and organized questionnaire for 재rk-related musculoskeletal was to 72Radiological Technologist, employed in 6general hospital in Seoul in September, 2003. The symptom prevalence rate of musculoskeletal symptoms were neck ($33.3\%$), shoulder ($33.3\%$), arm($12.5\%$), hand($13.9\%$), spine($34.7\%$)leg/knee/foot ($31.9\%$), arm/wrist/hand ($16.5\%$).