• Proceedings of the KWS Conference
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• 2010.05a
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• pp.21-21
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• 2010

AISI 316L 용접금속의 크롬/니켈 당량비에 따른 시그마상의 영향을 알아보기 위하여 응고모드가 다른 3종류의 플럭스 코어드 와이어를 제작하였다. AISI 316L 시편에 FCAW 프로세스를 적용한 용접재를 $650^{\circ}C$, $750^{\circ}C$, $850^{\circ}C$, $950^{\circ}C$에서 각 각 1H, 5H, 24H, 72H동안 열처리하였다. 크롬/니켈 당량비가 높을수록 즉, 크롬의 함량이 높아질수록 $\delta$-페라이트 함량은 증가하였으며, $\delta$-페라이트는 고온에서 시그마상으로 변태되었다. $\delta$-페라이트는 $650^{\circ}C$에서 가장 느리게 분해되었으며 $850^{\circ}C$에서 가장 활발히 분해되었다. 용접부의 특성상 크롬과 니켈 등의 합금원소에 의하여 응고온도범위가 넓어져 $950^{\circ}C$에서도 시그마상이 석출되었으며, 5시간 이상 유지 시 구형으로 존재하였다. 충격시험 시 시그마상에 의해 취약해진 inter-dendrite 를 따라 파면이 형성되었으며, $-100^{\circ}C$이하의 극저온에서는 시그마상의 양과 무관하게 충격흡수에너지는 0에 가까워졌다. 하지만 3%미만의 $\delta$-페라이트를 함유하는 AF모드에서 발생한 DDC와 미량의 시그마상은 충격흡수에너지에 결정적인 영향을 미치지 않았다.

• KIPS Transactions on Computer and Communication Systems
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• v.7 no.3
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• pp.67-72
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• 2018

Recently, noise reduction in an axial fan producing the small pressure rise and large flow rate, which is one type of turbomachine, is recognized as essential. This study describes the design and optimization techniques of MPI parallel program to simulate the flow-induced noise in the axial fan. In order to simulate the code using 100 million number of grids for flow and 70,000 points for noise sources, we parallelize it using the 2D domain decomposition. However, when it is involved many computing cores, it is getting slower because of MPI communication overhead among nodes, especially for the noise simulation. Thus, it is adopted the one-sided communication to reduce the overhead of MPI communication. Moreover, the allocated memory and communication between cores are optimized, thereby improving 2.97x compared to the original one. Finally, it is achieved 12x and 6x faster using 6,144 and 128 computing cores of KISTI Tachyon2 than using 256 and 16 computing cores for the flow and noise simulations, respectively.

• 한국신재생에너지학회:학술대회논문집
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• 2011.11a
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• pp.73.1-73.1
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• 2011

분류층 석탄가스화기에서 슬래그의 원활한 배출은 가스화 플랜트 운전 및 성능에 중대한 영향을 미치는 것으로 알려져 있다. 가스화기의 운전 온도에서 슬래그 점도가 일정수준 이상인 경우에는 가스화기 하부 슬래그 배출구 막힘 현상을, 일정 수준 이하일 경우에는 Membrane wall의 slag 두께가 얇아져 가스화기 수냉벽에 열적 악영향을 미친다. 가스화기의 안정적인 운전을 위한 석탄 선정 시, 석탄 슬래그의 용융온도 및 점도의 파악이 중요하다. 일반적으로 석탄슬래그의 용융온도는 ASTM D-1857 절차에 따른 환원분위기에서의 회융유온도(FT)측정을 통해, 점도는 고온점도측정 실험을 통해 분석하고 있다. 이런 실험적인 분석방법은 다양한 슬래그조성 및 온도 변화에 따른 영향을 살펴보기에는 많은 시간과 비용이 발생하므로 슬래그조성 및 온도 변화에 따른 용융온도 및 점도 예측이 필요하다. 본 연구에서는 200여 탄종의 회용유점 측정 결과와 FactSage에서 예측되는 슬래그 결정상 생성 및 회용유점(FT)에서의 고체분율과의 상관관계를 분석하였다. 이를 바탕으로 다양한 Ash 조성(SiO2, Al2O3, Fe2O3, CaO)에 대한 회용유점(FT)을 예측할 수 있는 프로그램을 개발하였다. 또한 50여 탄종의 슬래그 점도 측정 결과를 Facsage에서 예측되는 결정상 종류 및 Ash 조성을 기준으로 분류하였다. 결정상 종류 및 Ash 조성을 기준으로 기존 슬래그점도예측모델를 활용하여 보다 정확한 슬래그 점도 예측 프로세스를 개발하였다. 본 연구 결과는 플랜트 운전 결과 검증을 통하여 석탄 가스화 플랜트에 적합한 석탄의 선정, 혼탄 비율 및 첨가제 투입량 결정을 위해 활용될 것으로 기대된다.

• Journal of the Korean Institute of Gas
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• v.25 no.5
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• pp.37-51
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• 2021

The pressure drop phenomenon that occurs when the same flow rate is supplied to the gas regulator was analyzed. The regulator moves the position of the piston through the interaction of the force acting on the upper and lower parts of the piston and the spring tension to release the pressure of a specific range in a specific environment as constant pressure, thereby maintaining the pressure. The flow characteristics and pressure control process of the regulator were investigated through a numerical analysis technique as the volume of the fluid inside the regulator changed. As the gap between the piston and the piston seat decreased, the pressure drop increased and the flow velocity increased. It was verified through numerical analysis that the piston was positioned at 0.12mm under the same conditions as the pressure-flow test (inlet pressure 3MPa, outlet pressure 0.8MPa, flow rate 70kg/h).

• Land and Housing Review
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• v.13 no.1
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• pp.113-129
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• 2022

A building's eco-friendliness is directly related to various values including the life cycle cost of a building. However, the conventional architectural design method has a limitation in that it cannot create an optimized case according to the surrounding environmental conditions. Therefore, the purpose of this research is to present a design assistance tool that can review planning cases optimized for the environmental conditions of the building site in the planning stage of architectural production. To achieve the purpose of the study, an algorithm for realizing 3D modeling of the region and analysis of the solar environment was produced based on the site contours, building, and road information from the digital topographic map provided by the National Geographic Information Institute. To examine the validity of the developed algorithm, a comparative experiment was conducted targeting the elevation direction of the existing building. As a result, it was found that the optimal elevation direction selected by the algorithm can receive higher insolation compared to the front facade of the main building.

• Journal of Digital Convergence
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• v.19 no.11
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• pp.463-470
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• 2021

Due to natural and human factors, dunhuang frescoes in China have gradually degenerated. China has conducted digital transformation of frescoes since 1990. However, it requires expensive research costs. Most of the visitors passively accept transformation contents and lack subjective participation. The paper focuses on produces a prototype of Dunhuang frescoes on the CoSpaces EDU. It was implemented as a metaverse through procedures such as transforming the cave into 3D, mapping images to the cave model and developing CoBlocks. The research puts forward a more specific methodology without expensive costs of development. The paper makes it easier to realize the immersive and interactive virtual Dunhuang frescoes world, to improve the tourism contents and educational effect. This research carries on the statistics to the product result which develops according to the user experience of 100 different ages, has obtained the good feedback. The research results need to be improved is to strengthen the processing of graphic details. Therefore, Optimization and improvement of the result will be carried out in the future research.

• Archives of design research
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• v.20 no.3 s.71
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• pp.119-128
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• 2007

With the development of digital technologies, CAID became an essential part in the industrial design process. Creating photo-realistic images from a virtual scene with 3D models is one of the specialized task for CAID users. This task requires a complex interface of setting the positions and the parameters of camera and lights for optimal rendering results. However, the user interface of existing CAID tools are not simple for designers because the task is mostly accomplished in a parameter setting dialogue window. This research address this interface issues, in particular the issues related to lighting, by developing and evaluating TLS(Tangible Lighting Studio) that uses Augmented Reality and Tangible User Interface. The interface of positioning objects and setting parameters become tangible and distributed in the workspace to support more intuitive rendering task. TLS consists of markers, and physical controller, and a see-through HMD(Head Mounted Display). The user can directly control the lighting parameters in the AR workspace. In the evaluation experiment, TLS provide higher effectiveness, efficiency and user satisfaction compared to existing GUI(Graphic User Interface) method. It is expected that the application of TLS can be expanded to photography education and architecture simulation.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.12
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• pp.9-16
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• 2017

In this paper, the aerodynamic design process of wind turbine blades is established. The optimization design strategy is presented and the constraints that must be reviewed during the aerodynamic design process are summarized. Based on this, this study developed a BEMT-based aerodynamic optimal design program that can be applied easily to actual work, not only for research purposes, but also can be integrated from the initial concept design stage to the final 3D shape detail design stage. The developed program AeroDA consisted of a concept design module, basic design module, optimal TSR module, local shape optimization module, performance analysis module, design verification module, and 3D shape generation module. Using the developed program, an improved design of the 5MW blade by NREL was made, and it was confirmed that this program could be used for design optimization. In addition, a 10kW blade aerodynamic design and turbine detailed performance analysis were carried out, and it was verified by a comparison with the commercial program DNVGL Bladed.

• Korean Journal of Construction Engineering and Management
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• v.1 no.2 s.2
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• pp.98-107
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• 2000

Increased use of computers in AEC (Architecture, Engineering and Construction) has expanded the amount of information gained from CAD (Computer Aided Design), PMIS (Project Management Information System), Structural Analysis Program, and Scheduling Program as well as making it more complex. And the productivity of AEC industry is largely dependent on well management and efficient reuse of this information. Accordingly, such trend incited much research and development on ITC (Information Technology in Construction) and CIC (Computer Integrated Construction) to be conducted. In exemplifying such effort, many researchers studied and researched on IFC (Industry Foundation Classes) since its development by IAI (International Alliance for Interoperability) for the product based information sharing. However, in spite of some valuable outputs, these researches are yet in the preliminary stage and deal mainly with conceptual ideas and trial implementations. Research on unveiling the process of the IFC application development, the core of the Design Information management system, and its applicable plan still need be done. Thus, the purpose of this paper is to determine the technologies needed for Design Information management system using IFC, and to present the key roles and the process of the IFC application development and its applicable plan. This system play a role to integrate the architectural information and the structural information into the product model and to group many each product items with various levels and aspects. To make the process model, we defined two activities, 'Product Modeling', 'Application Development', at the initial level. Then we decomposed the Application Development activity into five activities, 'IFC Schema Compile', 'Class Compile', 'Make Project Database Schema', 'Development of Product Frameworker', 'Make Project Database'. These activities are carried out by C++ Compiler, CAD, ObjectStore, ST-Developer, and ST-ObjectStore. Finally, we proposed the applicable process with six stages, '3D Modeling', 'Creation of Product Information', 'Creation and Update of Database', 'Reformation of Model's Structure with Multiple Hierarchies', 'Integration of Drawings and Specifications', and 'Creation of Quantity Information'. The IFCs, including the other classes which are going to be updated and developed newly on the construction, civil/structure, and facility management, will be used by the experts through the internet distribution technologies including CORBA and DCOM.

• The Journal of Society for e-Business Studies
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• v.25 no.4
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• pp.143-154
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• 2020

With the increasing trend of making manufacturing system intelligent and autonomous, the introduction of robot-assist automation, like machine tending system for automated operation of CNC machine tools, is being actively carried out at many industrial sites. Most important part of this intelligent system to install machine tending system, is interface programming between the CNC machine tools and the industrial robot. Despite this importance, however, the machine tending system has many setup problems. it is necessary for difficult re-program of both controllers whenever a new CNC machine tool or robot is introduced. And, the helps of external engineers is required even though trivial changes due to the complex structure of the machine tending system. Authors of this paper introduces the integrated system of the interface between heterogeneous CNC machine tools and industrial robots. In addition, the digital twin implemented inside the machine tool controller enable shop-floor operators to change the interface programming easily. To implement this system, an integrated development environment for 1) an intelligent HMI platform that provide standardized interfaces to heterogeneous CNC machine tools and 2) a robot platform developing application software of various robots, was established. For easy un-tact environment, this paper explain the development of 3) a game-engine based web program of controlling and monitoring machine tending system remotely.