• Journal of the Korean Chemical Society
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• v.56 no.1
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• pp.54-57
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• 2012

New Schiff base derivatives of organoheterobimetallic-${\mu}$-oxoisopropoxide $[Bu_2SnO_2Ti_2(OPr^i)_6]$ have been synthesized by the thermal condensation ${\mu}$-oxoisopropoxide compound with Schiff bases in different molar ratios (1:1-1:4) yielded the compounds of the type $[Bu_2SnO_2Ti_2(OPr^i)_{6-n}(SB)_n]$ (where n is 1-4 and SB=Schiff base anion) respectively. The ${\mu}$-oxoisopropoxide derivatives have been characterized by elemental, spectral analysis (IR, $^1H$, $^{13}C$, $^{119}Sn$ NMR) and molecular weight measurement The studies reveal that the derivative compounds show monomeric nature. Further these are found less susceptible to hydrolysis as compared to parent compound and may prove excellent precursors for the mixed metal oxides.

• Journal of The Korean Association For Science Education
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• v.15 no.2
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• pp.201-212
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• 1995

The purpose of this study was to analyze science teaching models: Cognitive Conflict Teaching Model(CCTM), Generative Learning Model(GLM), Learning Cycle Model(LCM), Hypothesis-Testing Model(HTM), and Discovery Teaching Model(DTM). Using literature review, the models were analyzed and compared in several aspects; philosophical and psychological bases, primary goals and assumptions, syntax, implementation environments, and probable effects. The major finding were as follows; 1. Science teaching models had been diverse features. In the comparisons of science teaching models, some differences and similarities were founded. These were different in the degree of similarity and emphasis. 2. CCTM and GLM resemble each other in philosophical and psychological bases, primary goals and main assumptions, implementation environments, and probable effects. 3. LCM and HTM showed similarities in philosophical bases, syntax, and implementation environments. But differences were founded in other aspects These results showed that the diverse features of science teaching models should be considered in choosing a model for science teaching.

• Journal of Mechanical Science and Technology
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• v.19 no.3
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• pp.826-835
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• 2005

Exposed-type steel column bases are used widely in low-rise building construction. Numerous researchers have examined methods to identify their stiffness and strength, but those studies have heretofore been restricted to in-plane behaviors. This paper presents an experimental investigation of inelastic behaviors of square hollow section (SHS) steel column bases under biaxial bending. Two types of failure modes are considered : anchor bolt yielding and base plate yielding. Different pinching effects and interaction surfaces for biaxial bending are observed for these two modes during bi-directional quasi-static cyclic loading tests. Differences are elucidated using limit analyses based on a simple analytical model.

• IE interfaces
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• v.11 no.3
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• pp.103-114
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• 1998

This paper suggests a computer software system which generates standard times for assembly products. The system called "computer aided logical system for standard times(CALS4ST)" incorporates a modified bill of materials, BOM4ST(BOM for standard time) to deal with auxiliary operations which are not directly related to parts and assemblies listed in the standard BOM. Typical examples of the operations include inspection, adjustment, and repairing works to be done before or after assembly operations. Once standard time data bases for both the part assembly operations and the auxiliary operations are set up, the system relates the BOM4ST to the standard time data bases so as to calculate the standard time for a assembly part concerned. According to the structure of parts and auxiliary operations in the BOM4ST, their standard times stored in the data bases are to be sequentially added up considering the specified assembly-operation characteristics. To illustrate the feasibility of the system, the case study of L company is provided.

• Asian Journal of Turfgrass Science
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• v.10 no.2
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• pp.117-124
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• 1996

One new cellular slime mold, Dicivostelium valenstemmun sp. n. Shim et Chang, is isolated from the fermentation layer of soils in the cool temperate forests of Surak mountain, Korea. This species has the sori and sorophore yellow-pigmented, and sparse or irregular branches. And it is characterized by tall and robust sorocarps, well-form basal disks, mucoroides-type aggregations and large spores. This species has sorophores gradually tapering from bases to tips, simple capi- tate sorophore tips and conical bases. When prostrates on the plates, it has sparsely clavate bases. Spores are considerably large, 6.8~9.9 x 3.4~5.1 $\mu$m(avg. 8.5 x 4.1 $\mu$m), L /W index l.84~2.43(avg. 2.07) without polar granules. Key words: Diccyostelium valeustemmum, Cool temperate forests, Surak mountain.

• Steel and Composite Structures
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• v.19 no.4
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• pp.1035-1053
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• 2015

A genetic algorithm-based minimum weight design method is presented for steel frames containing composite beams, semi-rigid connections and column bases. Genetic Algorithms carry out optimum steel frames by selecting suitable profile sections from a specified list including 128 W sections taken from American Institute of Steel Construction (AISC). The displacement and stress constraints obeying AISC Allowable Stress Design (ASD) specification and geometric (size) constraints are incorporated in the optimization process. Optimum designs of three different plane frames with semi-rigid beam-to-column and column-to-base plate connections are carried out first without considering concrete slab effects on floor beams in finite element analyses. The same optimization procedures are then repeated for the case of frames with composite beams. A program is coded in MATLAB for all optimization procedures. Results obtained from the examples show the applicability and robustness of the method. Moreover, it is proved that consideration of the contribution of concrete on the behavior of the floor beams enables a lighter and more economical design for steel frames with semi-rigid connections and column bases.

• Journal of the Korean Mathematical Society
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• v.41 no.2
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• pp.345-368
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• 2004

A preconditioning algorithm is developed in this paper for the iterative solution of the linear system of equations resulting from the p-version boundary element approximation of the three dimensional integral equation with hypersingular operators. The preconditioner is derived by first making the nodal and side basis functions locally orthogonal to the element internal bases, and then by decoupling the nodal and side bases from the internal bases. Its implementation consists of solving a global problem on the wire-basket and a series of local problems defined on a single element. Moreover, the condition number of the preconditioned system is shown to be of order $O((1＋ln/p)^{7})$. This technique can be applied to discretization with triangular elements and with general basis functions.

• Proceedings of the KIEE Conference
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• 2001.07b
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• pp.699-701
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• 2001

The expert system monitoring and diagnosing 765kV power apparatus was described in this paper. To develop this expert system, we studied the knowledge bases and data bases for 765kV transformer and GIS. In order to make the reliable inference of knowledge base and the good MMI(Man Machine Interface), the data bases were consisted of the tables of power apparatus information, limit level value, measured input data, inference result and diagnosis result. The knowledge base had various rules to infer the conditions of transformer and GIS. We applied both the forward chaining and backward chaining methods to these rules of system for good inferences. This paper describes the applied methods for expert system. Also, this developed system was tested with dissolved gas analyzing result and the result was shown.

• Proceedings of the Polymer Society of Korea Conference
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• 2006.10a
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• pp.150-151
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• 2006

Perfluoroaryl boranes are widely employed as co-catalysts in olefin polymerization processes. Perfluoroaryl diboranes, possessing borane centers in close proximity, are a subclass of this family of compounds that are in theory capable of chelating neutral and anionic bases. The resulting anions are exceptionally weakly coordinating. We have prepared examples of such compounds and studied their coordination behavior with neutral Lewis bases that have the capability to bridge Lewis acid sites in an effort to delineate the kinetic and thermodynamic factors that influence bonding mode. When protic Lewis bases such as alcohols or water are reacted with diboranes, strong Bronsted acids capable of initiating cationic polymerizations under unusual conditions result.

• The Journal of the Korean dental association
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• v.12 no.9
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• pp.667-677
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• 1974

A testing machine was devised and constructed for the purpose of measuring the retentive forces of maxillary complete denture bases in subjects. Forth complete denture bases were made for ten subjects with three different denture base materials, following the usual denture construction technique. Retentive forces of the forty dentures were determined at seven locations. The tests on each base were repeated three times at intervals of 5 minutes. Differences in retention values were evaluated statistically. 1) Differences in retention values were found by the differences of the denture base materials, but acrylic resin was similar to chromium cobalt alloy. 2) The chromium cobalt alloy and acrylic resin bases from master models revealed the best retention values, the gold alloy base from master model was the poor second and the acrylic resin base from snap model was the third. 3) The retention values for hook-1 revealed higher than that for hook-2 and the retention values for hook-3 revealed the lowest value.