• Journal of Welding and Joining
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• v.30 no.6
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• pp.10-14
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• 2012

Recently the low alloy steel plate made with manganese-molybdenum is used widely in steam drum and separator of the new coal-fired power plant boiler. This material is suitable for the vapor storage of high pressure and high temperature. The high temperature creep strength of Mn-Mo alloy is higher than the carbon plate(SA516) that used in the subcritical pressure boiler. It reduces the thickness of the pressure vessel and makes the lightweight possible. Recently in the power plant boiler operation and production process, the damage has happened frequently in the heat affected zone and base material according to the hydrogen crack and delayed crack. This paper describes the research result about the damage case experienced in the boiler steam drum production process and present the optimum manufacture method for the similar damage prevention of recurrence.

• Journal of the Korean Society of Combustion
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• v.7 no.3
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• pp.9-15
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• 2002

Soot generation by combustion process has been investigated with objective of understanding of chemical reaction responsible for its formation in a coaxial laminar propane jet diffusion flame. For the direct photos, as the coflowing air flow rate is reduced, the area of soot luminous zone increases at first, then becomes smaller and smaller, and even disappears. The aspects of soot deposition can be acquired by using nine $15{\mu}m$ thin SiC fibers are positioned horizontally across the flame. Deposited soots on SiC fibers show the soot inception point and growth and soot oxidation zone in a typical propane diffusion. Soot is not generated anymore in a oxidizer deficient conditions of near-extinction and flame is fully occupied by transparent blue flame. It suggests that nonsooting pyroligneous blue reaction is being dominant in a oxidizer deficient ambience. In comparison with luminosities of SiC fibers and flame itself, indirect evidence is found that the process of soot nucleation and growth is endothermic reaction. It is remarkable that there exists two adjacent regions to have antithesis characteristics; one is exothermic reaction of blue flame and another endothermic reaction zone of soot formation.

• Archives of design research
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• v.19 no.3 s.65
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• pp.143-154
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• 2006

The primary purpose of this study was to investigate the influence of Cognitive Factors (CF) on the Creative Abilities (CAs) in design. We set up a model of Cognitive Design Process (CDP), which consists of four domains: Concepts, Experience, Five Senses (FS), and Thinking Modes (TM). Here, experience is first perceived by the five senses, and then recognized by intelligence. We regard design as a transforming process from concept to experience. For this study, two major Sensory Modalities (Visual and Kinesthetic), four Thinking Modes (Brain Dominance Profile), and four Creative Abilities (Fluency, Flexibility, Originality, and Elaboration) were reviewed. We hypothesized that idea generation is influenced by different Sensory Modalities (Visual Sense vs. Kinesthetic Sense) and Thinking Modes, and that these have a close relationship with the attributes of CAs. Firstly, we have examined the cognitive thinking model in design. Then, we adapted the Test of Creative Abilities of Design Thinking (TCADT) for measuring CAs. We surveyed the CAs under CF in particular. Finally, we have investigated the influences of the different Sensory Modalities (Visual Sense vs. Kinesthetic Sense) on CAs. It was found that a close relationship between Brain Dominance and CAs, and Sensory Modalities (SM) have different influence on these creative abilities. As a result, a tool for the Test of CAs and a framework for creative idea generation with the effective CF will be presented. These provide the basis for a new approach to creative idea generation in Experience Design.

• The Journal of Korea Robotics Society
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• v.4 no.4
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• pp.298-304
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• 2009

This paper describes an algorithm that improves 3D reconstruction result using a multi-sensor fusion disparity map. We can project LRF (Laser Range Finder) 3D points onto image pixel coordinatesusing extrinsic calibration matrixes of a camera-LRF (${\Phi}$, ${\Delta}$) and a camera calibration matrix (K). The LRF disparity map can be generated by interpolating projected LRF points. In the stereo reconstruction, we can compensate invalid points caused by repeated pattern and textureless region using the LRF disparity map. The result disparity map of compensation process is the multi-sensor fusion disparity map. We can refine the multi-sensor 3D reconstruction based on stereo vision and LRF using the multi-sensor fusion disparity map. The refinement algorithm of multi-sensor based 3D reconstruction is specified in four subsections dealing with virtual LRF stereo image generation, LRF disparity map generation, multi-sensor fusion disparity map generation, and 3D reconstruction process. It has been tested by synchronized stereo image pair and LRF 3D scan data.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.1283-1287
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• 2003

Reverse engineering technology refers to the process that creates a CAD model of an existing part using measuring devices. Recently, non-contact scanning devices have become more accurate and the speed of data acquisition has increased drastically. However, they generate thousands of points per second and various types of point data. Therefore. it becomes a important to handle the huge amount and various types of point data to generate a surface model efficiently. This paper proposes a new triangular mesh generation method using 3D grids. The geometric information of a part can be obtained from point cloud data by estimating normal values of the points. In our research, the non-uniform 3D grids are generated first for feature based data reduction based on the geometric information. Then, triangulation is performed with the reduced point data. The grid structure is efficiently used not only for neighbor point search that can speed up the mesh generation process but also for getting surface connectivity information to result in same topology surface with the point data. Through this integrated approach, it is possible to create surface models from scanned point data efficiently.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.33 no.12
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• pp.968-976
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• 2009

As the global warming becomes a serious environmental problem, studies of reducing $CO_2$ emission in power generation area are in progress all over the world. One of the carbon capture and storage(CCS) technologies is known as oxy-fuel combustion power generation system. In the oxy-fuel combustion system, the exhaust gas is mainly composed of $CO_2$ and $H_2O$. Thus, high-purity $CO_2$ can be obtained after a proper $H_2O$ removal process. In this paper, an oxy-fuel combustion cycle that recovers the waste heat of a high-temperature fuel cell is analyzed thermodynamically. Variations of characteristics of $CO_2$ and $H_2O$ mixture which is extracted from the condenser and power consumption required to obtain highly-pure $CO_2$ gas were examined according to the variation of the condensing pressure. The influence of the number of compression stages on the power consumption of the $CO_2$ capture process was analyzed, and the overall system performance was also investigated.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2001.04a
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• pp.422-428
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• 2001

The term High Speed Machining has been used for many years to describe end milling with small diameter tools at high rotational speeds, typically 10,000 - 100,000 rpm. The process was applied in the aerospace industry for the machining of light alloys, notably aluminium. In recent year, however, the mold and die industry has begun to use the technology for the production of components, including those manufactured from hardened tool steels. With increasing cutting speed used in modern machining operation, the thermal aspects of cutting become more and more important. It not only directly influences in rate of tool wear, but also will affect machining precision recognized as thermal expansion and the roughness of the surface finish. Hence, one needs to accurately evaluate the rate of cutting heat generation and temperature distributions on the machining surface. To overcome the heat generation, we used to cutting fluid. Cutting fluid play a roles in metal cutting process. Mechanically coupled effectiveness of cutting fluids affect to friction coefficient at tool-work-piece interface and cutting temperature and chip control, surface finish, tool wear and form accuracy. Through this study, we examined the behavior of heat generation in high-speed machining and the cooling performance of various cooling methods.

• Journal of the Korea Society for Simulation
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• v.23 no.4
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• pp.21-29
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• 2014

In general, a simulation project requires much time and money since we should develop a model that works similarly to the system at a level consistent with the project purposes. Therefore, more active research studies are required to reduce the time needed for the modeling process. This is achievable by minimizing the possible trial and error during the model development process through the appropriate conceptual model design and the automated generation of the simulation model. This paper presents a tool automatically generating an Arena model after developing a conceptual simulation model. Because our proposed tool is based on the popular Microsoft Excel and Visio, it is expected to be practically used at many industrial sites. Finally, we showed the effectiveness of the newly suggested tool by applying it to an imaginary simulation project.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.25 no.4
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• pp.22-31
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• 2002

A high-speed rail system represents a typical example of large-scale multi-disciplinary systems, consisting of subsystems such as train, electrical hardware, electronics, control, information, communication, civil technology etc. The system design and acquisition data of the large-scale system must be the subject under strict configuration control and management. Not only the requirements of the large-scale system dictate the contracts with the suppliers but also become the basis for the development process, project execution, system integration, and testing. The requirements database provide the system design specification of all development activities. Using the RDD-100, a systems engineering tool, the Korea next-generation high-speed rail program can establish requirements traceability and development process management in performing the enabling train technology development projects. This paper presents the results from a computer-aided systems engineering application to the Korea next-generation high-speed railway project. Especially, the focus of the study was on requirement management and PBS(Product Breakdown Structure) management.

• International journal of advanced smart convergence
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• v.7 no.2
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• pp.7-21
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• 2018

The author studied the process of unifying Hanja variant groups of Korea and China for LGR (Label Generation Rule) of Internet Top-Level Hangeul Hanja Domain and possible confusion between Hangeul syllable and Hanja character. Among 3518 Chinese variant groups, Korea and China need not review variant groups which include no or just one Korean Hanja character. Korea and China reviewed 304 Chinese variant groups (9% of the 3518 Chinese variant groups) which include two or more Korean Hanja characters. By doing so, Korea and China succeeded in efficiently unifying variant groups. Unification process of variant groups which is the main core of Korea-China coordination and almost final unification result is summarized in this paper. In addition, the author analyzed systematically whether some Hanja character could be confused with a Hangeul syllable and obtained a good result which was not expected at the beginning. Probably this kind of systematic analysis has not been performed in the past and seems the first attempt, which is one of the contributions of this paper. The author also reviewed how to express K-LGR in XML for submission to ICANN.