• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2001.05a
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• pp.540-545
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• 2001

In case of small motors, coil bundle occupies a large portion of stator in view of mass and volume as well as dynamics. It is observed through modal test on the stator of an IPM BLDC (interior permanent magnet brushless direct current) motor that coil bundle wound on the stator core causes the first and second natural frequencies to decrease by about 20-30% compared with those of bare stator. Especially the third natural frequency is newly observed below 3 KHz, which is not observed on the bare stator. It is found that at the third mode the end-coil and the core vibrate out of phase in radial direction. In this paper, the stator is dynamically modeled in terms of the core and the coil bundle consisting of the end-coil and the slot coil based on the above observations for the prediction of dynamic properties. The core can easily be modeled using finite element method with its actual material properties and geometric shape. The concept of equivalent bending stiffness is used for modeling of the end-coil so that predictions may match with the measured natural frequencies for the end-coil cut out of the stator. Although the same concept can be applied to the slot coil, separation of the slot coil from the stator is impractical. Therefore, equivalent bending stiffness of the slot coil is determined through iterative comparisons with the measurements of natural frequencies of the stator with the slot coil in it.

• International conference on construction engineering and project management
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• 2011.02a
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• pp.591-596
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• 2011

There are quite a number of business processes in the urban regeneration project. Managers and participants who involved in the project make and use information for the best way to perform in the particular business process. The information can be also reused and produced for data at the next stage. Accordingly, the information sometimes goes out of existence and work data up into new information when the urban regeneration project has been accomplished. But in that case some of changes happen occasionally, the business for urban regeneration has suffered a loss of profit and time as result of confusions about decisions and inappropriate action. For that reason, the information should be analyzed to achieve its aim at the business process under the influence of changes. Then, even though detail processes and management method change, the Core Information, which are important factors for accomplishing the project, help that the project can be operated to solve the problem about confusion and loss of the business. In conclusion, the Core Information is main effective factors for successful urban regeneration projects on the change management. The purpose of this study is to research the information according to the Information-flow and changes, and to find out the influence factors and the Core Information to manage efficiently at the process of urban regeneration projects.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.32 no.10
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• pp.118-126
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• 2004

The propulsive characteristics of oscillating flat plates are investigated using a discrete vortex method. The plates and their wakes are represented by discrete point vortices. To analyze the closely coupled aerodynamic interference between the plates, a vortex core model and a vortex core addition scheme are combined. A calculated wake shape for a flat plate in heaving oscillation is compared with flow visualization. The effect of wake shapes on the propulsive characteristics of the plates in pitching oscillation is investigated. The propulsive characteristics of oscillating plates with three cases (1. one is stationary and another is oscillating, 2. both oscillating in phase, 3. both oscillating out of phase) are calculated. The plates oscillating out of phase showed the largest thrust force among the three cases.

• Journal of Korea Game Society
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• v.13 no.5
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• pp.55-62
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• 2013

Since large terrain data can not be loaded on the GPU or CPU memory at once, out-of-core methods which read necessary part from the secondary storage such as a hard disk are commonly used. However, long delay may occur due to limited bandwidth while loading the data from the hard disk to memory. We propose efficient rendering method of large terrain data, which compresses the data with wavelet technique and save its coefficients in RGBA channel of an image us, then decompresses that in rendering stage. Entire process is performed in GPU using Direct Compute. By reducing the amount of data transfer, performing wavelet computations in parallel and doing decompression quickly on the GPU, our method can reduce rendering time effectively.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.42 no.1
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• pp.49-60
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• 2005

The Back Bone of gearing portion between Core Network System which is used in wire and wireless system is No.7 Protocol. ISUP( ISDN User Part), INAP handling in Intelligent Network and MAP gearing method for linking each Network Element System in mobile network have use of No.7 signaling. Therefore, it is require for system to detect the problem - operating problem occurs in Core Network which use No.7 signaling or the existing problem that is not recognized - in shortest time. This paper study out analyzing and measuring system for No.7 protocol and analyzing out system whether out of order or not. It can abstract No.7 Signaling Message and analyze system performance and report it. This system is connected in system No.7 HW Module which is in charge of No.7 Signaling. It is not offer Emulator function and Simulation function for any scenario but offer monitoring No.7 signaling. This system perform the function about No.7 MTP, ISUP, INAP and MAP and is offered several wire and wireless network Operator. It can detect and correct SW system, HW system and operating system problem. From now on, this system may offer the function about A-interface which is gearing between BSC and MSC, so it will perform to analyze generally and prompt effective operating for Core Network system.

• Nuclear Engineering and Technology
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• v.24 no.1
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• pp.52-62
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• 1992

Radioactive nuclides deposited on out-of-core surface after the radiation in the core by the transport of corrosion products (CRUD) through the primary coolant system in PWR which is the major plant type in Korea, are leading sources of radiation exposure to plant maintenance personnel. Thus, the optimal chemistry operation method is required for the reduction of radiation exposure by the corrosion products. This study analysed the actual water chemistry operation data of four operating domestic PWRs. And in order to evaluate the coolant chemistry operation data, a computer code which can calculate the activity buildup in the various chemistry conditions of PWR coolant was employed. Through the analysis of comparison between the activity buildup of actual water chemistry operation mode and that of assumed Elevated Li operation mode calculated by the computer code, it was found that the out-of core radioactivity can be reduced by diminishing the deposition of corrosion products on the core in case that the Elevated Li operation mode is applied to the coolant chemistry operation of PWR. And the higher coolant pH operation was shown to have the advantage of the reduction of out-of-core activity buildup if the integrity of system structural materials and fuel cladding is guaranteed.

• Journal of Industrial Technology
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• v.23 no.A
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• pp.149-156
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• 2003

The development and maintenance of a sound bond are essential requirements of concrete repair and replacement. The bond property of a overlay to its substrate concrete during the lifetime is one of the most important performance requirements which should be quantified. A standard or a verified bond strength measurement method is required at field for screening, selecting materials and quality control for overlay or repair materials, but no test method has been adopted as a standard. In this study, a concrete pull off bond strength measurement method for field application is proposed and evaluated. This study compares the splitting tensile test, slant shear test, nipple pipe direct tensile test, flexural adhesion test, briquette tensile test, jumbo nail pull-out test and core pull-off test with their test procedures. From these comparison and investigation, core pull-off test is selected as a main topic of this study because of it's suitability for in situ testing, simplicities in field application and clearness at interface boundary condition. Thus, the proposed core pull off test is evaluated to be the most appropriate method for field application in a simple manner. The fracture surface and fracture mode could be easily determined by visual observation of failure surface of the field specimen. The core pull off test was found to be sensitive to surface condition and latex contents at latex modified concrete.

• Journal of Pharmaceutical Investigation
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• v.16 no.1
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• pp.12-17
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• 1986

Etilefrine hydrochloride was microencapsulated with ethylcellulose by phase separation method to develop a sustained release dosage form. The results of dissolution test carried out with various microcapsules showed that the drug release was decreased with increasing the particle size of microcapsules at a constant core to wall ratio, and with decreasing the core to wall ratio. Also ethylcellulose 50 cps and fast stirring rate (900 rpm) was better in decreasing the drug release than ethylcellulose 22 cps and slow stirring rate (300 rpm), respectively.

• Steel and Composite Structures
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• v.21 no.3
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• pp.605-628
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• 2016

The energy absorption characteristics of diamond core sandwich cylindrical columns under axial crushing process depend greatly on the amount of material which participates in the plastic deformation. Both the single-objective and multi-objective optimizations are performed for columns under axial crushing load with core thickness and helix pitch of the honeycomb core as design variables. Models are optimized by multi-objective particle swarm optimization (MOPSO) algorithm to achieve maximum specific energy absorption (SEA) capacity and minimum peak crushing force (PCF). Results show that optimization improves the energy absorption characteristics with constrained and unconstrained peak crashing load. Also, it is concluded that the aluminum tube has a better energy absorption capability rather than steel tube at a certain peak crushing force. The results justify that the interaction effects between the honeycomb and column walls greatly improve the energy absorption efficiency. A ranking technique for order preference (TOPSIS) is then used to sort the non-dominated solutions by the preference of decision makers. That is, a multi-criteria decision which consists of MOPSO and TOPSIS is presented to find out a compromise solution for decision makers. Furthermore, local and global sensitivity analyses are performed to assess the effect of design variable values on the SEA and PCF functions in design domain. Based on the sensitivity analysis results, it is concluded that for both models, the helix pitch of the honeycomb core has greater effect on the sensitivity of SEA, while, the core thickness has greater effect on the sensitivity of PCF.

• Proceedings of the IEEK Conference
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• 2002.07b
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• pp.1320-1323
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• 2002

This paper reviews the Korean government’s selection process of core wireless communications technologies, and presents technology trends, perspectives and strategies of 5 core technologies to develop in wireless communications areas based on the mid term IT technology development plan(2002∼2004). Delphi Panel Method and Analytic Hierarchy Process(AHP) Analysis were adapted to select 30 core technologies in 9 strategic areas. Especially, 5 core wireless communications technologies out of 24 required technologies are selected: 4 G Core Technology, Broadband Wireless Access Network Technology, IMT-2000 Plus STP Technology, OBP Based Multimedia Satellite Communications Technology, Stratosphere Communications System Technology. Strategic national IT R&D program has been essential to continue success story of CDMA technology, and acquiring technology independency from advanced nations. In long term perspectives, a strategy of intensive investment with prudent selection onto core technologies should be deployed in the IT R&D programs. Also, the national IT R&D programs should be limited in the high risk & high returen areas where only government can afford the failures as well as better spill over effects are expected for the technology development and national economy. Korean industry has some strength in wireless communications technology area. Therefore, more policy concerns should be given into this area not only to secure present strength but also to explore better technology competitiveness.