• Journal of the Korean Society of Manufacturing Process Engineers
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• v.13 no.1
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• pp.85-91
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• 2014

The rotation of a spindle unit must be accurate for high-quality machining and to improve the quality of the machine tools. Therefore, the proper measurement of the rotation accuracy and ensuring a proper analysis are very important. Separate processes are necessary because spindle errors and roundness errors associated with the test balls can both factor into the measured rotation error values. We used three methods to discern test ball errors and analyzed which could be deemed as the most proper technique in a test of the rotation accuracy of the main spindle of a machine tool.

• Structural Monitoring and Maintenance
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• v.3 no.2
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• pp.175-194
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• 2016

Based on the change of traditional viscoelastic damper structure, a brand-new damper is designed to control simultaneously the translational vibration and the rotational vibration for platforms. Experimental study has been carried out on the mechanical properties of viscoelastic material and on its multi-dimensional seismic response control effect of viscoelastic damper. Three types of viscoelastic dampers with different shapes of viscoelastic material are designed to test the influence of excited frequency, strain amplitude and ambient temperature on the mechanical property parameters such as circular dissipation per unit, equivalent stiffness, loss factor and storage shear modulus. Then, shaking table tests are done on a group of single-storey platform systems containing one symmetric platform and three asymmetric platforms with different eccentric forms. Experimental results show that the simulation precision of the restoring force model is rather good for the shear deformation of viscoelastic damper and is also satisfied for the torsion deformation and combined deformations of viscoelastic damper. The shaking table tests have verified that the new-type viscoelastic damper is capable of mitigating the multi-dimensional seismic response of offshore platform.

• Journal of the Korean Regional Science Association
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• v.13 no.2
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• pp.93-118
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• 1997

Main findings of this study are as follows. Time-space model of Korea for urban growth model is established. The variables of space model resulted in job and education, which both are significant at 0.01 level and positive. The effect of job and education on the urban growth are 0.76 and 0.29 respectively in average. the determinants for deciding the influences for job variable are income variable and price-level variable. Income variable contributes 68.66% and the direction is negative while contribution of price-level variable is 29.90% and the direction is positive. The determinants for education variable are income, unemployment and wage difference between university graduates and high school graduates. The contribution and the high school graduates. The contribution and the direction of each variable for education variable are 63.6% and positive for the unemployment variable, 15.99% and negative for the income variable and 13.75% and positive for the wage difference variable. This study in different from previous works in three ways. The first is to establish the time-space model which could consider the time and space factor simultaneously. The second is to build data bases which contain the data of almost every city and every year in Korea during the objective period, which make the analysis continuous. The third is that the general analytic framework for the study is macrosocial one rather than a behavioral one, which means the unit of analysis is the metropolitan community and each city occupies population actively through it's potential power such as jobs, education and so on rather than a city population is the passive result of migration.

• Computational Structural Engineering
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• v.10 no.4
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• pp.155-164
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• 1997

A reactor pressure vessel, which contains fuel assemblies and reactor vessel internals, has the thermal stress resulting from the cool-down and heat-up of the vessel wall in combination with the pressure stress from system pressure resulting in large stresses. The combination of the pressure stress and thermal stress along with a decrease in fracture toughness may cause through-wall propagation of a relatively small crack. Therefore, it is necessary to define the relations between operating pressure and temperature during cool-down and heat-up. In this study, theory of fracture mechanics for a pressure/temperature limit curve is investigated and a numerical procedure for generating it is developed. Plant-specific limit curves for the Kori unit 1 plant, the oldest nuclear power plant in Korea, have been obtained for several cooling and heating rates and their results are discussed.

• Journal of the korean Society of Automotive Engineers
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• v.15 no.1
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• pp.55-66
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• 1993

The characteristics of the flow processes in the cylinder of the two-stroke cycle engines have become the subject of increasing and attention owing to the simplicity and the higher power per unit weight of the two-stroke cycle engine. Among the many factors which influence on the scavenging flow, the port angle is important factor. Hence, four different type models with one inlet-port and two side-ports are studied to show the effect of port angle on the laminar scavenging flow. When the inlet-port axial is relatively larger than the side-port axial angle, it is showed that the fresh charge penetrate into the burned gas and displace it first toward the cylinder head and then toward the exhaust port. When the inlet-port axial angle is much less than the side-port axial angle, the fresh charge through the inlet-port directly move toward the exhaust port. The result showed that the model A may suppress the generation of vortices in the vicinity of inlet and side prots which restrict the sufficient supply of fresh charge and obstruct the perfect displacement of all combustion products.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.15 no.2
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• pp.1-6
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• 2001

Tunnel lighting in Korea has the problems of unsatisfactory illuminance uniformity which obstructs driver's vision, a flicker phenomenon on wall of tunnel, a heavy glare, low efficiency of luminaires, low utilization factor, and high energy consumption. We developed a high efficiency luminaire reflector for tunnel lighting which removes these problems. Developed luminaire saves energy and improves lighting environment by increasing 10% of luminaire efficiency. It can reduce installation cost by decreasing the number of luminaires, while average illuminance of 200[lx], overall uniformity of 0.4, longitudinal uniformity of 0.7, and electric power consumptions per unit area of 3.7[W/m$^2$] are accomplished.

• Journal of Drive and Control
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• v.18 no.1
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• pp.9-16
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• 2021

Overloaded vehicles increase the maintenance cost of road structures, and they are a major factor in causing damage to the roads and bridges. In addition, overloaded vehicles compromise the braking capability of the vehicle; thus, threatening the safety of the driver. In order to prevent overloading of vehicles, the government is cracking down on the roads by using a device that measures the weight of vehicles. But this process is inconvenient because the place where the equipment is installed is far away from where the cargo is loaded. Due to the limitations of these fixed weighing devices, there is a growing need for technology that can monitor vehicle weight distribution and overload conditions in real time. In this work, we develop an onboard scale that can measure the load (weight) of trucks in real time. The onboard scale consists of high sensors, a signal processing unit, and a display, and it measures the load using height-displacement of the vehicle's leaf spring suspension.

• Proceedings of the Korea Information Processing Society Conference
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• 2010.11a
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• pp.1784-1787
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• 2010

General Purpose Graphic Processing Unit (GPGPU) computing is a technique that utilizes the high-performance many-core processors of high-end graphic cards for general-purpose computations such as 3D graphics, video/image processing, computer vision, scientific computing, HPC and many more. GPGPUs offer a vast amount of raw computing power, but programming is extremely challenging because of hardware idiosyncrasies. The open computing language (OpenCL) has been proposed as a vendor-independent GPGPU programming interface. OpenCL is very close to the hardware and thus does little to increase GPGPU programmability. In this paper we present how a set of digital camera image signal processing (ISP) filters can be realized efficiently on GPGPUs using OpenCL. Although we found ISP filters to be memory-bound computations, our GPGPU implementations achieve speedups of up to a factor of 64.8 over their sequential counterparts. On GPGPUs, our proposed optimizations achieved speedups between 145% and 275% over their baseline GPGPU implementations. Our experiments have been conducted on a Geforce GTX 275; because of OpenCL we expect our optimizations to be applicable to other architectures as well.

• Transactions of the Korean Society of Automotive Engineers
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• v.17 no.5
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• pp.97-106
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• 2009

An objective of this study is to give practical information that could be used for calculating pollutant emission factors and fuel economy from Korean Inspection & Maintenance program, which has been using steady state acceleration simulation mode. Concentration results from I/M test is adequately converted to mass emission factors and fuel efficiency data, which have unit of g/km and km/L, respectively. Exhaust volume flow(EVF), which is for converting emission result from concentration to mass, is measured by tracer method in various vehicle speed - power condition. It is found that there is an apparent second order relationship between EVF and vehicle inertia weight. EVF is expressed in function of vehicle inertia weight in order to estimate EVF in I/M site without measuring device. Converted mass emission results from measured EVF and raw emission analyzer show a satisfactory agreement with those from conventional CVS-bag type measurement system. Mass emission factors and fuel efficiency from measured EVF and estimated EVF also show good agreement to each other. Considering that an I/M program has great advantages to recruit-based emission test in terms of the number of test vehicle, the information in this study can be used for developing an alternative procedure to collect more various data to establish national database of mobile emission factors and fuel economy, even though the driving cycle in I/M program is steady state cycle rather than transient cycle.

• Journal of Radiation Protection and Research
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• v.39 no.4
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• pp.176-181
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• 2014

The object of this paper is to evaluate the fission product inventories and radiological doses in a non-LOCA event, based on the U.S. NRC's regulatory methodologies recommended by the TID-14844 and the RG 1.195. For choosing a non-LOCA event, one fuel assembly was assumed to be melted by a channel blockage accident. The Hanul nuclear power reactor unit 6 and the CE $16{\times}16$ fuel assembly were selected as the computational models. The burnup cross section library for depletion calculations was produced using the TRITON module in the SCALE6.1 computer code system. Based on the recently licensed values for fuel enrichment and burnup, the source term calculation was performed using the ORIGEN-ARP module. The fission product inventories released into the environment were obtained with the assumptions of the TID-14844 and the RG 1.195. With two kinds of source terms, the radiological doses of public in normal environment reflecting realistic circumstances were evaluated by applying the average condition of meteorology, inhalation rate, and shielding factor. The statistical analysis was first carried out using consecutive three year-meteorological data measured at the Hanul site. The annual-averaged atmospheric dispersion factors were evaluated at the shortest representative distance of 1,000 m, where the residents are actually able to live from the reactor core, according to the methodology recommended by the RG 1.111. The Korean characteristic-inhalation rate and shielding factor of a building were considered for a series of dose calculations.