• Transactions of the Korean Society of Mechanical Engineers B
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• v.28 no.6
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• pp.638-645
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• 2004

A new micro actuation concept is introduced and studied in this paper. This idea is based on the thermo-pneumatic actuation principle. In order to improve the performance of a conventional thermo-pneumatic actuator, the idea of bistable buckling is added. By using a membrane which has the bistable buckling characteristics, the working pressure difference can be increased and as a result the work output can be increased. The analysis model for each phenomenon, bistable buckling and phase change, are suggested and the each model is verified with experimental data. From the comparison of the theoretical prediction with the experimental results, it can be concluded that these models are useful for such micro actuator analysis.

• Proceedings of the KIEE Conference
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• 1996.07a
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• pp.50-52
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• 1996

The exiting apparatus for rectilinear reciprocating motion has low efficiency because of various mechanical converting equipments from rotary motion. The LOA(Linear Oscillation Actuator) is the rectilinear reciprocating actuator. This paper shows the operating principle of bifiler winding LOA and the comparison the characteristics of thrust force of no tapered moving core type LOA with the tapered one. Through FEM analysis tapered LOA has the lower peak force and longer stroke than no tapered LOA.

• Proceedings of the KIEE Conference
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• 1996.07a
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• pp.74-76
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• 1996

This measurement method described in this paper can be applied for the accurate determination for voltage and current of inverter with harmonics. The method, based on a thermal principle, relies on adaptation of the measurement thermal e.m.f to signal of inverter and comparison of AC to DC signals. The performance of the measurement system is compared with calculated results and reference power system. With this method, an accuracy of 0.1% can be achieved.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 1998.06a
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• pp.573-578
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• 1998

In this paper, we propose a new technique of codification. The purpose of this method is to take in consideration the natural language nuances and the fuzziness that characterizes the human reasoning. So, we warranted a means of more flexible encoding that translates as well the linguistic descriptions. Its principle is simple and intuitive. It consists simply in replacing in ambiguous cases, a unique number by an interval. The introduction of the new codification necessitates the elaboration of metric or similarity in order to compare two intervals. This comparison must take in consideration the difference of their size, the remoteness of their center and the width of their intersection. In consequence, we defined three new fuzzy concepts : "fuzzy inclusion degree", "fuzzy resemblance degree," and " fuzzy curve".

• Journal of KSNVE
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• v.10 no.2
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• pp.229-239
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• 2000

To reduce the drag rise on the advancing helicopter rotor blade tips, the tip of the blade is modified to have sweep, anhedral and pretwist. The equations of motion of rotor blade with these tip angles were derived using Hamilton principle, programmed using FORTRAN and named as ARMDAS(Advanced Rotorcraft Multidisplinary Design and Analysis System). Rotating frequency analysis of rotor blades with swept tipe was performed that is necessary in conceptual and preliminary design phases of the helicopter design. Vibration analysis of non-rotating blades was also accomplished and compared with MSC/NASTRAN resutls for the basis of comparison with the vibration test data. The rotating frequency analysis of blades with an actual rotor blade data was also performed to verify coded program and to check the possibility of a resonance of an actual rotor blade at the specific rotating speed.

• Journal of Technology Innovation
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• v.15 no.2
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• pp.177-209
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• 2007

This work firstly aims to analyse the balance between tangibles and intangibles as well as among human capital, structural capital and relational capital of evaluation indicators for the research institutes in science and technology sector conducted in 2006, by adopting intellectual capital model. The research question of this work comes from that while the R&D activity can produce both tangibles and intangibles, there have no been methodologies to relevantly measure and rationally judge these, in particular, intangible performance. The result shows that the institute evaluation system in 2006 had given more weight on tangibles and structural capital than intangibles and other intellectual capitals such as human capital and relational capital, in comparison to the past evaluation system, even though, in principle, the current evaluation system has to deal with the intangible research performances as well as tangible ones in economic, social and cultural perspective. Finally, based on these analysis, I will try to suggest some policy directions for overcoming the deficits of indicators in institute evaluation system.

• International Journal of Concrete Structures and Materials
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• v.10 no.2
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• pp.189-203
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• 2016

This paper investigates on the use of advanced optical measurement methods, i.e. 3D coordinate measurement machines (3D CMM) and stereo-vision digital image correlation (3D DIC), for the mechanical analysis of shear deficient prestressed concrete members. Firstly, the experimental program is elaborated. Secondly, the working principle, experimental setup and corresponding accuracy and precision of the considered optical measurement techniques are reported. A novel way to apply synthesised strain sensor patterns for DIC is introduced. Thirdly, the experimental results are reported and an analysis is made of the structural behaviour based on the gathered experimental data. Both techniques yielded useful and complete data in comparison to traditional mechanical measurement techniques and allowed for the assessment of the mechanical behaviour of the reported test specimens. The identified structural behaviour presented in this paper can be used to optimize design procedure for shear-critical structural concrete members.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 2001.12a
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• pp.314-318
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• 2001

Constructing a shortest path on a graph is a fundamental problem in the area of graph theory. In an application where we cannot exactly determine the weights of edges, fuzzy weights can be used instead of crisp weights, and Type-2 fuzzy weights will be more suitable if this uncertainty varies under some conditions. In this paper, shortest path problem in type-1 fuzzy weighted graphs is extended for type-2 fuzzy weighted graphes. A solution is also given based on possibility theory and extension principle.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.10 no.4
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• pp.8-15
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• 2011

In this paper, the influence of a crack on the natural frequency of cracked cantilever L-shaped beam with coupled bending and torsional vibrations by analytically and experimentally is analyzed. The L-shaped beam with a crack is modeled by Hamilton's principle with consideration of bending and torsional energy. The two coupled governing differential equations are reduced to one sixth-order ordinary differential equation in terms of the flexural displacement. The crack is assumed to be in the first, second and third mode of fracture and to be always opened during the vibrations. The theoretical results are validated by a comparison with experimental measurements. The maximal difference between the theoretical results and experimental measurements of the natural frequency is less than 7.5% in the second vibration mode.

• Korean Journal of Agricultural and Forest Meteorology
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• v.4 no.4
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• pp.197-202
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• 2002

A new method is used to estimate the amount of water evaporation from Class A Pan with higher precision and accuracy. The principle of method is to detect the weight change of a buoyant sinker resulting from a change in water level of Class A Pan. A strain-gauge load cell is used to measure the weight change. Field observation of evaporation was done at Pohang Meteorological Station from June 24 to August 4, 2002. By using this new method, it is possible to measure hourly evaporation accurately even under a strong solar radiation and wind disturbance, enabling a direct comparison of evaporation with other meteorological elements. At night, under low humidity and high wind speed conditions, more evaporation was recorded than during daytime. Maximum evaporation rates observed during this period exceed 1.0 mm/hour under the sunny and windy conditions with low humidity. To understand relationships between meteorological elements and latent heat flux at ground level, we suggest intensive held experiments using high accuracy evaporation recording instruments with hourly time interval.