• Proceedings of the KSMRM Conference
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• 2001.11a
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• pp.108-108
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• 2001

Purpose： To correlate the histological differentiation of hepatocellular carcinomas (HCCs) with finding on triple contrast-enhanced MR imaging using gadolinium-chelates, superparamganetic ire oxides (SPIO), and mangafodipir trisodium. Method： Ten patients with proven HCC underwent triple contrast-enhanced MRI befo surgical resection. Subjective ratings of the enhancement pattern and degree were compare with the histological grades determined on surgical specimen. Quantitative measurements signal-to-noise ratio (S/N) of the lesion and the lesion-to-liver contrast-to-noise ratio C/N on the enhanced MR images, and the degree of S/N and C/N changes between the unenhanced and enhanced images were also correlated with the histological grades.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.05a
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• pp.88-92
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• 2004

Mufflers have been important elements in engineering practice, which reduce various kinds of noises because of its general capability of application. Many kinds of methods :Ire applied to analyze their characteristics and to expect their performances. Some of the methods, conventionally, are based on the plane wave assumption for its simplicity. The shortcoming of this approach is its limitation of analysis ranges and parameters related with analysis and response. This research employs the boundary element method f3r the analysis of mufflers, which considers 3 dimensional scattering effects. This method can be used more appropriately fur tile analysis of mufflers because its analysis ability for higher frequency range which can be decided by the element size of the model. And, experimental analysis using a reciprocity theorem is conducted to verify the analysis results.

• Journal of the Korean Society of Safety
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• v.13 no.1
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• pp.40-46
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• 1998

This paper is presented that theoretical optimization design method in order to consider mass reduction for the structural safety In this paper, it described methods for reducing vibration in structural safety by the determination of the optimum sizes and locations of tunning masses through formal mathematical optimization techniques. The optimization procedure which employs the tunning masses and corresponding locations is developed. Design variables are systematically changed to achieve low values of shear without a large mass penalty. Three optimization methods ire developed and tested. The first is based on minimizing the modal shaping parameter which indirectly reduce the modal shear amplitudes corresponding to each harmonic of airload. The second method reduces these amplitudes directly and the third method reduces the shear as a function of time during a revolution of the blade. The first method works well for reducing the shear for one mode responding to a single harmonic of the airload but has been found in some bases to be ineffective for more than one mode.

• 제어로봇시스템학회:학술대회논문집
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• 2000.10a
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• pp.518-518
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• 2000

We have researched quantitative structure activity relationships between molecular structure of medicines and physiological activity. Since they are non-linear, neural networks are useful tool to research them. There are many ranks for the non-linearity; therefore, the neuron function must be selected carefully. As the results of some trial calculations, Ire find the sigmoid-linear functions pair. We call the neural network constructed of the pair as ANN. The inter- or extrapolation abilities of the ANN are excellent; therefere, ANN is a superior predictor for the relationships. We evaluated the anticarcinogenic medicines, Carboquinone derivatives, by the developed ANN and leave-one-out method.

• Journal of the Korean institute of surface engineering
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• v.36 no.5
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• pp.398-405
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• 2003

The stainless steel wire requires good corrosion resistance and mechanical properties, such as drawing ability, combined with a high resistance to corrosion. For increasing drawing ability of stainless steel, Ni coating methods have been used in this study. However, there is no information on the electrochemical corrosion behavior of drawed wires after Ni coating. To investigate corrosion resistance and mechanical property of drawed wire, the characteristics of Ni coated wires have been determined by tensile strength tester, hardness tester, field emission scanning microscope, energy dispersive x-ray analysis and potentiodynamic method in 0.1 M HCl. The drawed stainless steel wires showed the strain-induced martensitic structure, whereas non-drawed stainless steel wire showed annealing twin in the matrix of austenitic structure. The hardness and tensile strength of drawed stainless steel wire were higer than that of non-drawed stainless steel wire. Electrochemical measurements showed that, in the case of drawed stainless steel o ire after Ni coating, the corrosion resistance and pitting potential increased compared with non-coated and drawed stainless steel wire due to decrease in the surface roughness.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 2000.05a
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• pp.264-267
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• 2000

The need for including time variables in various type of modeled Discrete Event Dynamic Systems(DEDSs) is apparent since the modeled systems are real time in nature. In the real world, almost all event is related to time. A Time Petri Net(TPN) is one of methods for model ins and analyzing of DEDSs with real time values. Two time values, ${\alpha}$$\sub$i/ and ${\beta}$$\sub$i/ are defined for each transition. In this paper, Ire present Fuzzy Transition Timed Petri Net(FTTPN) to determine the optimal transition firing time between ${\alpha}$$\sub$i/ and ${\beta}$$\sub$i/ using fuzzy theory. The traffic signal controller in an intersection is modeled and analyzed by FTTPN.

• Proceedings of the KIEE Conference
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• 1998.11b
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• pp.481-483
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• 1998

In general, spatial filtering method was proposed to simplify measurement system through parallel Processing hardware. Spatial filtering is a method of detection that we can get a spatial pattern information, as we process a special space pattern, to say, as we process spatial parallel process by using the spatial weighting function. The important processing characteristics will be depended in according to how ire design a spatial weighting function, a spatial sensitive distribution. The form of the weighting function which is realized from the generally used spatial filtering is fixed and the weighting value was already became a binary-value. In this paper, we propose a new method in order to construct adaptive measurement systems. This method is a weighting function design to make multi-valued and variable.

• Journal of the Korean Society of Clothing and Textiles
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• v.15 no.4 s.40
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• pp.405-416
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• 1991

This paper examined the risks perceived by consumers in apparel buying situation by 1) measuring the contents and perception level of risk, 2) categorizing each risk into meaningful factors (risk types), 3) analyzing the relationships between risk types and consumers' demo-graphic variables. 224 respondents deliberately selected to include each level of S demographic variables were contacted with 37-item question3.ire. Factor analysis showed that 32-item perceived risk could be categorized into 6 risk types: psychological. social, economic, time/convenience loss, fashionability loss, performance risk. Psychological risk were perceived highest in terms of perception level while social and performance risk showed relatively low perception level. 4 of 5 demographic variables including sex, education level, income, occupa-tion showed partial relationship with each risk type after ANOVA and Duncan test. Sex had the greatest influence on risk perception level and each age level (20's, 30's, 40's) showed different risk structure.

• Journal of the Optical Society of Korea
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• v.6 no.2
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• pp.48-54
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• 2002

Experimental study is performed on flashlamp-pumped Ti: sapphire lasers with single, double, and four-partial-ellipse-pump cavities aiming at improving the performance of the lasers. The output energy of 604 mJ per pulse with a width of 25 $\mu$s at a total laser efficiency of 0.13% is achieved in the laser pumped by a light pulse of 45$\mu$s without a fluorescent converter The laser output energy versus its Ti: sappy ire rod length, pumping-light pulse duration, and electrical input energy are discussed with or without using a fluorescent converter. The result shows that much more output energy is obtained il a longer Ti: sapphire-rod laser pumped by a shorter light pulse when its output coupler has an optimized transmittance. In addition, an enhancement of output energy by a factor of 7 is achieved. in the laser using a fluorescent converter LD490.

• Research in Mathematical Education
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• v.18 no.3
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• pp.187-208
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• 2014

This study engages in the features of interaction in elementary school mathematics lessons as reflected in the class discourse. 28 pre-service teachers documented the discourse during observation of their tutor-teachers' lessons. Mapping the interaction patterns was performed by a unique graphic model developed for that purpose and enabled providing a spatial picture of the discourse conducted in the lesson. The research findings present the known discourse pattern "initiation-response-evaluation / feedback" (IRE/F) which is recurrent in all the lessons and the teacher's exclusive control over the class discourse patterns. Hence, the remaining time of the lesson for the pupils' discourse is short and meaningless.