• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2009.06a
• /
• pp.182-182
• /
• 2009

The effect of Re-oxidation on the PTCR properties of Sm-doped barium titanate ceramics was investigated by means of impedance spectroscopy. Electrical properties such as resistance vs. temperature, I-V curve were measured and microstructure was observed with SEM photography. Sample was fabricated with thick film process such as tape casting of green sheet, screen printing of electrode pattern, stacking, firing in reduced atmosphere and re-oxidation, etc. As the temperature of re-oxidation increases, resistance jump as a function of temperature enhances but resistance at room temperature increases. These behavior of resistance as a function of temperature, dependent on the re-oxidation condition, is analyzed with Cole-Cole impedance plot and is shown to be related with the degree of oxidation of grain boundary regardless of grain core during re-oxidation process of sample.

• Proceedings of the KIEE Conference
• /
• 1996.07a
• /
• pp.127-129
• /
• 1996

A 3-dimensional analysis is desired for a magnet of magnetically levitated vehicle because the geometrical shape of the magnet is complicated and nonsymmetric. A FEM package of FLUX3D is used to analyze the characteristic of the magnet. Various quantities could be observed like levitation force, flux density distribution along the air gap, edge and fringing effect, leakage flux pattern, etc. The simulation results from FLUX3D are compared with those of 2-D analysis and test results. There are a little difference between results due to the boundary conditions and magnetized B-H curve of the core.

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.17 no.8
• /
• pp.2079-2087
• /
• 1993

The effects of subcooling and natural convection are studied numerically on the melting process of an initially subcooled phase-change medium filled inside a horizontal circular cylinder. It is postulated that melting continues with the tube wall kept at a constant temperature and with the unmelted solid core fixed. Primary emphasis is placed on the evolution of interface morphology, the local/overall heat transfer rate at the tube wall and at the interface, and the structure of natural convection. The numerical results are mainly presented in terms of the Rayleigh and subcooling numbers. As the degree of subcooling intensifies, the melting rate and the movement of the interface are impeded but the interfaces are of similar shape with the passage of time. The heat transfer characteristics are found to be mostly governed by the formation pattern of natural convection in the liquid phase. Good agreement with available experimental data is found.

• Proceedings of the Korean Operations and Management Science Society Conference
• /
• 2004.05a
• /
• pp.409-412
• /
• 2004

Today, meta-heuristic algorithms have been much attention by researcher because they have the power of solving combinational optimization problems efficiently. As the result, many variants of a meta-heuristic algorithm (e.g., simulated annealing) have been proposed for specific application domains. However, there are few efforts to classify them into a unified software framework, which is believed to provide the users with the reusability of the software, thereby significantly reducing the development time of algorithms. In this paper, we present an object-oriented framework to be used as a general tool for efficiently developing variants of simulated annealing algorithm. The interface classes in the framework achieve the modulization of the algorithm, and the users are allowed to specialize some of the classes appropriate for solving their problems. The core of the framework is Algorithm Configuration Pattern (ACP) which facilitates creating user-specific variants flexibly. Finally, we summarize our experiences and discuss future research topics.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2004.10a
• /
• pp.1452-1455
• /
• 2004

Sandwich structures, which are composed of a thick core between two thin faces, are commonly used in many engineering applications because they combine high stiffness and strength with low weight. Depending on the application of a particular sandwich structure, various types of cores can be used. The production of sandwich sheets by a rolling process, which is a more efficient and economical approach compared to other types of processes, has become an increasingly important subject of study. In this paper, we have studied the embossing structure of sheet type and developed embossing roll mold with $\Phi$3 pattern and roll forming system.

• Proceedings of the Korean Society of Applied Pharmacology
• /
• 1994.04a
• /
• pp.329-329
• /
• 1994

OMZ과 HP-$\beta$-CD 포접화합물의 유형은 $A_{L}$ type의 가용성 복합체이며, CD, UV, IR, DSC, XRD pattern 및 $^1$H-NMR 방법으로 측정한 포접화합물의 결함형태는 OMZ의 benzimidazole부분이 HP-$\beta$-CD 공동에 포접된 형태이었고, OMZ과 HP-$\beta$-CD의 결합조성몰비는 1:1, 안정도 상수는 약 34 M$^{-1}$이었다. 또한 cholestyramine 수지와 OMZ 복합체는 방출양상이 신속하였다. OMZ-cholestyramine 수지염은 안정성이 양호하고 용출율이 우수한복합체로 경구용 재제를 개발할 수 있었으며, 용출시험 및 산 저항성이 양호하고 pellet의 제조에 있어서 core의 제조는 정제수 : 에탄올(7: 3) 결합액을 이용하여 lactose를 주로 사용하고 기타 PEG 6000, sorbitol, Avicel PH101, sodium lauryl sulfate 및 무수 PVP K-30을 적절히 배합하여 제조하고, 장용코팅의 내산성은 90.5% 이었으며, 소장에서의 용출경향이 85%이상이 10분 이내에 용출되어 규정에 적합하였다.

• Journal of Information Processing Systems
• /
• v.2 no.2
• /
• pp.124-129
• /
• 2006

With the explosive increase in the generation and utilization of spatiotemporal data sets, many research efforts have been focused on the efficient handling of the large volume of spatiotemporal sets. With the remarkable growth of ubiquitous computing technology, mining from the huge volume of spatiotemporal data sets is regarded as a core technology which can provide real world applications with intelligence. In this paper, we propose a 3-tier knowledge discovery framework for spatiotemporal data mining. This framework provides a foundation model not only to define the problem of spatiotemporal knowledge discovery but also to represent new knowledge and its relationships. Using the proposed knowledge discovery framework, we can easily formalize spatiotemporal data mining problems. The representation model is very useful in modeling the basic elements and the relationships between the objects in spatiotemporal data sets, information and knowledge.

• Journal of Electrical Engineering and Technology
• /
• v.11 no.1
• /
• pp.175-183
• /
• 2016

This paper brings out a novel method for reducing Near end and Far end Crosstalk using Electromagnetic Band Gap structures (EBG) in High Speed RF transmission lines. This work becomes useful in high speed closely spaced Printed Circuit Board (PCB) traces connected to multi core processors. By using this method, reduction of −40dB in Near-End Crosstalk (NEXT) and −60 dB in Far End Crosstalk (FEXT) is achieved. The results are validated through experimental measurements. Time domain analysis is performed to validate the signal integrity property of coupled transmission lines.

• Proceedings of the Korean Institute of Interior Design Conference
• /
• 2004.05a
• /
• pp.176-179
• /
• 2004

Space is comprised by the movements of human beings, and draws a complex locus within it. That form seems to be complex of movement around in all directions of space axis, and be ever-changing process as time goes by. Although Human are able to move uninhibitedly, the movements are restricted to a narrow sphere during locomotion. However, the pattern of these movements delineates a certain frame within the space, and provides not only visual effects but also relevance tomovement itself. Also, critically dividing and organizing this sphere is what is realized into this tangible indoor space. This study recognized importance of human being as a core of making indoor space and brought out experimental approach on relationship human with space, and visually perceptual standpoint. And this presented the recent possibility of action and attitude though sight and walking by arranging space on the basis of modern artists' perception of human body.

• Journal of Electrical Engineering and Technology
• /
• v.8 no.6
• /
• pp.1345-1351
• /
• 2013

Variable iron loss as function of current phase angle of Interior Permanent Magnet Synchronous Motor(IPMSM) was calculated through Curve Fitting Method(CFM). Also, a magnetic flux density distribution of iron core according to current phase angle was analyzed, and an iron loss calculation was performed including harmonic distortion. The experiment was performed by production of non-magnetizing model for the separation of mechanical loss, and the iron loss was calculated by the measurement of input using power analyzer and output power using dynamometer. Some error was generated between experimental results and calculation value, but an iron loss diminution according to current phase angle followed a same pattern. So, errors were generated by measurement, vibration, noise, harmonic distortion loss, etc.