• 품질경영학회지
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• 제49권1호
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• pp.31-45
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• 2021

Purpose: A noncentral composite design method is to be developed to explore farther region for the first factorial design. A general guideline for sequential experimentation is provided. Methods: (1) A non-overlapping noncentral composite design (NNCD) is developed, in which the second factorial design shares one design point that indicates the best response value in the first factorial design. (2) Four composite designs are compared in terms of the four design evaluation criteria, which are D-, A, G, and I-optimality. (3) A follow-up design strategy is suggested based on the interaction effect, direction of improvement, number of factors. Results: (1) NNCD and model building method are presented, which is useful for exploring farther region from first factorial design block. (2) The performances of the four composite designs are compared. (3) A follow-up design strategy is suggested. Conclusion: (1) NNCD will be useful to explore farther region for the first factorial design. (2) A follow-up design strategy can be beneficial to the experimental practitioners for product and process design and improvement.

• 대한안전경영과학회지
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• 제25권1호
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• pp.23-29
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• 2023

Among the Additive Manufacturing (AM) technologies, the Binder-Jetting printing technology is a method of spraying an adhesive on the surface of powder and laminate layer by layer. Recently, this technique has become a major issue in the production of large casting products such as ship-building, custom vehicles and so on. In this study, we performed research to make actual mold castings and increase mechanical property by using special sand and water-based binders. For use as a mold, it has a strength of more than 3MPa and permeability. Various experiments were carried out to obtain suitable them. The major process parameters were binder jetting volume, binder types, layer thickness and heat treatment condition. As a result of this study, the binder drop quantity was measured to be about 60 pico-liter, layer thickness was 100㎛ and the heat treatment condition was measured about 1,000℃ and compressive strength were measured to be more than 5MPa. The optimum condition of this experiment was established through actual casting of aluminum. The equipment used in this study was a Freeforms T400 model (SFS Co., Ltd.), and the printing area of 420 * 300 * 250mm and resolution of 600dpi can be realized.

• Smart Structures and Systems
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• 제4권2호
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• pp.221-232
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• 2008

This paper represents the final results of a research program sponsored by the European Commission through project WIND-CHIME ($\underline{W}$ide Range Non-$\underline{IN}$trusive $\underline{D}$evices toward $\underline{C}$onservation of $\underline{HI}$storical Monuments in the $\underline{ME}$diterranean Area), in which the possibility of using advanced seismic protection technologies to preserve historical monuments in the Mediterranean area is investigated. In the current research, the dynamic characteristics of two outstanding Mamluk-Style minarets, which similar minarets were reported to experience extensive damage during Dahshur 1992 earthquake, are investigated. The first minaret is the Qusun minaret (1337 A.D, 736 Hijri Date (H.D)) located in El-Suyuti cemetery on the southern side of the Salah El-Din citadel. The minaret is currently separated from the surrounding building and is directly resting on the ground (no vaults underneath). The total height of the minaret is 40.28 meters with a base rectangular shaft of about 5.42 ${\times}$ 5.20 m. The second minaret is the southern minaret of Al-Sultaniya (1340 A.D, 739 H.D). It is located about 30.0 meters from Qusun minaret, and it is now standing alone but it seems that it used to be attached to a huge unidentified structure. The style of the minaret and its size attribute it to the first half of the fourteenth century. The minaret total height is 36.69 meters and has a 4.48 ${\times}$ 4.48 m rectangular base. Field investigations were conducted to obtain: (a) geometrical description of the minarets, (b) material properties of the minarets' stones, and (c) soil conditions at the minarets' location. Ambient vibration tests were performed to determine the modal parameters of the minarets such as natural frequencies and mode shapes. A $1/16^{th}$ scale model of Qusun minaret was constructed at Cairo University Concrete Research Laboratory and tested under free vibration with and without SMA wire dampers. The contribution of SMA wire dampers to the structural damping coefficient was evaluated under different vertical loads and vibration amplitudes. Experimental results were used along with the field investigation data to develop a realistic 3-D finite element model that can be used for seismic risk evaluation of the minarets. Examining the updated finite element models under different seismic excitations indicated the vulnerability of such structures to earthquakes with medium to high a/v ratio. The use of SMA wire dampers was found feasible for reducing the seismic risk for this type of structures.

• Spatial Information Research
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• 제20권6호
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• pp.129-137
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• 2012

극한(寒)지에서 건설사업을 수행하기 위해서는 건설의 초기 단계인 기획, 설계단계부터 지형자료와 같은 현지에 대한 기반 데이터가 반드시 요구되며, 필요에 따라 수시로 현지조사를 수행할 필요가 있다. 그럼에도 극한지는 지역적 특성상 대부분 원거리에 있고 접근이 용이하지 않다는 특성이 있으며, 특히 남극과 같은 특수지역은 현지 조사를 수행하는 것 자체가 어렵고, 현지조사를 수행한다 해도 현지를 방문할 수 있는 인원이 매우 제한적이어서 대부분은 현장을 모르고 건설에 참여하게 됨으로써 의사결정 오류나 설계 오류 등이 발생할 확률이 높아지게 된다. 따라서 본 연구에서는 이러한 문제를 해결고자 남극 장보고기지 건설지 주변을 연구대상지로 선정하여 원격탐사를 통해 광역적 지형데이터와 노출지반 암석분류데이터를 구축하는 방법과 건설부지에 대해서는 정밀 지형데이터를 구축하는 방법 등을 살펴보았다. 또한, 3차원 GIS 기술을 통해 이러한 데이터를 통합적으로 관리하고 가시화함으로써 모든 건설참여자가 현장 감각을 익히고 수시로 필요한 분석을 수행할 수 있도록 하는 방법을 제시하고자 하였다. 이를 통해 건설사들이 실제 극한지 건설공사를 수행하고자 할 때 현지 공간데이터를 DB화하고 3차원 가시화함으로써 건설환경을 필요시 마다 분석할 수 있어 의사결정이나 설계 등 건설 업무를 지원할 수 있을 것으로 기대한다.

• 복합신소재구조학회 논문집
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• 제2권4호
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• pp.1-10
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• 2011

본 연구는 각 연결부에 대한 수치 해석을 통하여 강재-콘크리트 합성 프레임 구조물의 성능을 조사하였다. 본 연구의 혁신적인 측면은 강재 보와 CFT 기둥의 연결부 사용과 저탄소강과 형상 기억 합금 구성요소의 조합을 활용하는데 있다. 이러한 새로운 연결부의 목적은 지진 후 건물의 손상과 잔류 흐름을 줄이기 위해 고탄성 형상기억합금 인장부에서 발생하는 교정 작용과 저탄소강의 우수한 에너지 분산 능력을 활용하는 것이다. 연결부의 핀, 전체적인 고정 또는 부분 구속으로 모델링을 할 수 없기 때문에 이러한 구조물들의 해석과 설계는 복잡하여 PR-CFT 연결부의 전체적인 거동을 알기 위한 수치해석을 위해 정교한 3차원 솔리드 요소로 구성된 유한해석 모델을 개발하였다. 이러한 유한요소 해석으로 얻은 결과를 바탕으로 스프링 요소를 이용하여 간단한 연결부 모델링을 공식화 시켰다. 반복 하중을 가하여 전체 프레임 구조물의 거동을 확인하였고 3D 유한요소 해석을 통하여 단순 거동을 비교하였다.

• 한국측량학회지
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• 제38권2호
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• pp.131-140
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• 2020

Recently the importance of BIM (Building Information Modeling) that enables 3D location-based design and construction work is being highlighted around the world. In Korea, the road map has been established to settle the design based on BIM using drone survey results by 2025. As the first step, BIM would be applied to road construction projects worth more than 50 billion Korean Won from 2020. On the other hand, drone survey regulation has been enacted and the data for drone survey cost were also included on Standard of construction estimate in 2020. However, more careful improvement is required to reflect drone survey results in BIM design and construction. Currently, Engineering instructions and Standard of construction estimate specifies that earthwork volume must be calculated by cross section method only. So it is required to add the method of DEM (Digital Elevation Model) based volume calculation on these regulations to realize BIM application. In order for that, this study verified the method of DEM based earthwork volume calculation. To get an accurate DEM for accurate volume computation, drone survey was carried out according to the drone survey regulation and then could get an accurate DEM data which have errors less than 3cm in X, Y and 6.8cm in H. As each DEM cell has 3D coordinate component, the volume of each cell can be calculated by obtaining the height of area of the cell then total volume is calculated by multiplying total number of cells by volume of each cell for the construction area. Verification for the new calculation method compare with existing method was carried out. The difference between DEM based volume by drone survey and cross section based volume by traditional survey was less than 1.33% and it can be seen that new DEM method will be able to be applied to BIM design and construction instead of cross section method.

• 대한건축학회논문집:구조계
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• 제34권9호
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• pp.3-10
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• 2018

While computer environments have been dramatically developed in recent years, as the building structures become larger, the structural analysis models are also becoming more complex. So there is still a need to model one shear wall with one finite element. From the viewpoint of the concept of FEA, if one shear wall is modeled by one finite element, the result of analysis is not likely accurate. Shear wall may be modelled with various finite elements. Among them, considering the displacement compatibility condition with the beam element connected to the shear wall, plane stress element with in-plane rotational stiffness is preferred. Therefore, in order to analyze one shear wall with one finite element accurately, it is necessary to evaluate finite elements developed for the shear wall analysis and to develop various plane stress elements with rotational stiffness continuously. According to the above mentioned need, in this study, the theory about a plane stress element using hierarchical interpolation equation is reviewed and stiffness matrix is derived. And then, a computer program using this theory is developed. Developed computer program is used for numerical experiments to evaluate the analysis results using commercial programs such as SAP2000, ETABS, PERFORM-3D and MIDAS. Finally, the deflection equation of a cantilever beam with narrow rectangular section and bent by an end load P is derived according to the elasticity theory, and it is used to for comparison with theoretical solution.

• 기술혁신학회지
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• 제13권3호
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• pp.423-445
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• 2010

본 논문은 연구개발과 이공계 고등교육의 상호 연계를 통한 시너지 극대화를 위한 사이버 인프라스트럭처에 기반한 차세대 연구 교육 융합환경의 구축방안을 제시하고자 수행되었다. 국가 R&D 사업을 통하여 생성 및 축적된 연구결과를 이공계 대학 및 대학원의 교육 현장에 직접 연계시킬 수 있는 방안을 마련하고자 하였다. 먼저 사이버인프라 기반의 연구개발 패러다임의 변화를 검토하였다. 이어서 연구성과를 교육에 활용하여 연구과 교육의 융합을 도모한 모형과 사례들을 분석하였다. 이러한 선행연구를 바탕으로 해서 우리나라 실정에 적합한 연구 교육 융합환경 시스템을 제안하였고, e-AIRS의 사례를 들어서 구체적으로 설명하였다. 마지막으로 이러한 사업을 추진하기 위한 정책적 과제들을 논의하였다.

• Asia pacific journal of information systems
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• 제23권3호
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• pp.25-53
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• 2013

This study analyzes the effect of Computer Aided Innovation (CAI) to improve R&D Capabilities empirically. Survey was distributed by e-mail and Google Docs, targeting CTO of 235 SMEs. 142 surveys were returned back (rate of return 60.4%) from companies. Survey results from 119 companies (83.8%) which are effective samples except no-response, insincere response, estimated value, etc. were used for statistics analysis. Companies with less than 50billion KRW sales of entire researched companies occupy 76.5% in terms of sample traits. Companies with less than 300 employees occupy 83.2%. In terms of the type of company business Partners (called 'partners with big companies' hereunder) who work with big companies for business occupy 68.1%. SMEs based on their own business (called 'independent small companies') appear to occupy 31.9%. The present status of holding IT system according to traits of company business was classified into partners with big companies versus independent SMEs. The present status of ERP is 18.5% to 34.5%. QMS is 11.8% to 9.2%. And PLM (Product Life-cycle Management) is 6.7% to 2.5%. The holding of 3D CAD is 47.1% to 21%. IT system-holding and its application of independent SMEs seemed very vulnerable, compared with partner companies of big companies. This study is comprised of IT infra and IT Utilization as CAI capacity factors which are independent variables. factors of R&D capabilities which are independent variables are organization capability, process capability, HR capability, technology-accumulating capability, and internal/external collaboration capability. The highest average value of variables was 4.24 in organization capability 2. The lowest average value was 3.01 in IT infra which makes users access to data and information in other areas and use them with ease when required during new product development. It seems that the inferior environment of IT infra of general SMEs is reflected in CAI itself. In order to review the validity used to measure variables, Factors have been analyzed. 7 factors which have over 1.0 pure value of their dependent and independent variables were extracted. These factors appear to explain 71.167% in total of total variances. From the result of factor analysis about measurable variables in this study, reliability of each item was checked by Cronbach's Alpha coefficient. All measurable factors at least over 0.611 seemed to acquire reliability. Next, correlation has been done to explain certain phenomenon by correlation analysis between variables. As R&D capabilities factors which are arranged as dependent variables, organization capability, process capability, HR capability, technology-accumulating capability, and internal/external collaboration capability turned out that they acquire significant correlation at 99% reliability level in all variables of IT infra and IT Utilization which are independent variables. In addition, correlation coefficient between each factor is less than 0.8, which proves that the validity of this study judgement has been acquired. The pair with the highest coefficient had 0.628 for IT utilization and technology-accumulating capability. Regression model which can estimate independent variables was used in this study under the hypothesis that there is linear relation between independent variables and dependent variables so as to identify CAI capability's impact factors on R&D. The total explanations of IT infra among CAI capability for independent variables such as organization capability, process capability, human resources capability, technology-accumulating capability, and collaboration capability are 10.3%, 7%, 11.9%, 30.9%, and 10.5% respectively. IT Utilization exposes comprehensively low explanatory capability with 12.4%, 5.9%, 11.1%, 38.9%, and 13.4% for organization capability, process capability, human resources capability, technology-accumulating capability, and collaboration capability respectively. However, both factors of independent variables expose very high explanatory capability relatively for technology-accumulating capability among independent variable. Regression formula which is comprised of independent variables and dependent variables are all significant (P<0.005). The suitability of regression model seems high. When the results of test for dependent variables and independent variables are estimated, the hypothesis of 10 different factors appeared all significant in regression analysis model coefficient (P<0.01) which is estimated to affect in the hypothesis. As a result of liner regression analysis between two independent variables drawn by influence factor analysis for R&D capability and R&D capability. IT infra and IT Utilization which are CAI capability factors has positive correlation to organization capability, process capability, human resources capability, technology-accumulating capability, and collaboration capability with inside and outside which are dependent variables, R&D capability factors. It was identified as a significant factor which affects R&D capability. However, considering adjustable variables, a big gap is found, compared to entire company. First of all, in case of partner companies with big companies, in IT infra as CAI capability, organization capability, process capability, human resources capability, and technology capability out of R&D capacities seems to have positive correlation. However, collaboration capability appeared insignificance. IT utilization which is a CAI capability factor seemed to have positive relation to organization capability, process capability, human resources capability, and internal/external collaboration capability just as those of entire companies. Next, by analyzing independent types of SMEs as an adjustable variable, very different results were found from those of entire companies or partner companies with big companies. First of all, all factors in IT infra except technology-accumulating capability were rejected. IT utilization was rejected except technology-accumulating capability and collaboration capability. Comprehending the above adjustable variables, the following results were drawn in this study. First, in case of big companies or partner companies with big companies, IT infra and IT utilization affect improving R&D Capabilities positively. It was because most of big companies encourage innovation by using IT utilization and IT infra building over certain level to their partner companies. Second, in all companies, IT infra and IT utilization as CAI capability affect improving technology-accumulating capability positively at least as R&D capability factor. The most of factor explanation is low at around 10%. However, technology-accumulating capability is rather high around 25.6% to 38.4%. It was found that CAI capability contributes to technology-accumulating capability highly. Companies shouldn't consider IT infra and IT utilization as a simple product developing tool in R&D section. However, they have to consider to use them as a management innovating strategy tool which proceeds entire-company management innovation centered in new product development. Not only the improvement of technology-accumulating capability in department of R&D. Centered in new product development, it has to be used as original management innovative strategy which proceeds entire company management innovation. It suggests that it can be a method to improve technology-accumulating capability in R&D section and Dynamic capability to acquire sustainable competitive advantage.

• 한국추진공학회지
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• 제19권4호
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• pp.15-23
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• 2015

본 연구는 유한요소해석 기반의 Helmholtz solver인 ASCI3D를 사용하여 예혼합 가스터빈 연소기에서 연소불안정 현상과 관련된 주요 결과들을 예측하였다. 해석결과는 실험결과와 비교할 때 일반적인 불안정 특성 예측에는 성공하였으나, 불안정 구간이 나타나는 영역을 다소 과대 예측하는 경향이 발견되었다. 이를 개선하기 위한 노력으로 반사계수가 불안정 특성에 미치는 영향이 분석되었다. 결과로부터 반사계수는 불안정 특성에 큰 영향을 미치고, 정확한 예측 결과를 얻기 위해서는 정확한 음향 경계 조건의 정의가 필수적인 것으로 나타났다.