• 대한토목학회논문집
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• 제37권4호
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• pp.705-716
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• 2017

산업화 시대를 지나며 많은 환경오염문제가 발생함에 따라, 친환경적이며 지속 가능한 발전을 위해 건설 산업계에도 환경성 평가 관련한 다양한 연구가 수행되고 있다. 그러나 설계단계 활용을 목적으로 토목시설물의 부위별 설계 대안에 대한 신속한 환경부하 산정 방법론은 부재하다. 이에 본 연구는 Pre-Stressed Concrete (PSC) beam교량을 대상으로 구조물 주요 부위별 표준단면을 이용한 환경부하 산정을 위한 선행연구로서, 설계초기 단계에서의 대표물량정보 기반 환경부하량을 효율적으로 산정할 수 있는 설계부위 및 공종정보 기준을 구축하는 것을 목표로 하였다. 이를 위해 25개 PSC Beam교량 사례에 대한 상세설계자료를 기반으로 ISO 14040의 전과정평가(Life Cycle Assessment, LCA) 수행절차를 통한 상세환경부하량 데이터베이스를 구축하였으며, 목적 및 범위는 교량의 자원제조 및 수송단계와 시공단계만으로 한정하였다. 또한, 환경부하발생에 영향이 높은 부위별 대표공종을 선정하여, 이러한 부위 및 공종분류에 따른 소요자원 및 8대 영향범주 별 환경부하량 특성분석을 수행하였다. 그 결과 교량의 특성상 상부공이 전체 42.91%의 환경부하량으로, 상부공중에서는 주요 자재인 레미콘이 53.13%, PSC beam공이 31.25%로 나타났다. 또한, 하부 교대 교각공에서는 주요 자재인 레미콘, 철근, 시멘트가 93%이상으로 대부분을 차지하였다. 향후 이러한 교량 부위별 대표공종 및 자재 정보들은 설계단계에서 구조물의 특성이 반영된 개략 환경부하량 모델 구축시 활용될 수 있을 것이다.

• 한국기계가공학회지
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• 제14권5호
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• pp.107-112
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• 2015

Increased productivity and cost reduction have emerged as the main goals of the industry due to the development of the machinery industry, and mechanical materials with excellent properties with the development of the machine tool industry are widely used in machine parts or structures. In addition, the cutting process of production plays a pivotal role in the production technology. Studies on cutting have involved a lot of research on the material, the cutting tool, the processing conditions, and numerical analysis. Due to the development of the computer through numerical analysis, cutting conditions, the assessment of cutting performance, and cutting quality could be predicted. This research uses the creation of the material model and AdvantEdge Production module for the NC code analysis. To improve the productivity, this research employs the optimization method to reduce cutting time.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2004년도 춘계학술대회 논문집 반도체 재료 센서 박막재료 전자세라믹스
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• pp.30-33
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• 2004

Shallow p+-n junctions were formed by low-energy ion implantation and dual-step annealing processes The dopant implantation was performed into the crystalline substrates using $BF_2$ ions. The annealing was performed with a rapid thermal processor and a furnace. FA+RTA annealing sequence exhibited better junction characteristics than RTA+FA thermal cycle from the viewpoint of junction depth. A new simulator is designed to model boron diffusion in silicon, which is especially useful for analyzing the annealing process subsequent to ion implantation. The model which is used in this simulator takes into account nonequilibrium diffusion, reactions of point defects, and defect-dopant pairs considering their charge states, and the dopant inactivation by introducing a boron clustering reaction. Using a resonable parameter values, the simulator covers not only the equilibrium diffusion conditions but also the nonequilibrium post-implantation diffusion. Using initial conditions and boundary conditions, coupled diffusion equation is solved successfully. The simulator reproduced experimental data successfully.

• Journal of Electrochemical Science and Technology
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• 제12권4호
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• pp.398-405
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• 2021

To fabricate a full-scale pilot model of the cost-effective Na-(Ni,Fe)Cl₂ cell, a Na-beta-alumina solid electrolyte (BASE) was developed by applying a one-step synthesis cum sintering process as an alternative to the conventional solid-state reaction process. Also, Fe metal powder, which is cheaper than Ni, was mixed with Ni metal powder, and was used for cathode material to reduce the cost of raw material. As a result, we then developed a prototype Na-(Ni,Fe)Cl₂ cell. Consequently, the Ni content in the Na-(Ni,Fe)Cl₂ cell is decreased to approximately (20 to 50) wt.%. The #1 prototype cell (dimensions: 34 mm × 34 mm × 235 mm) showed a cell capacity of 15.9 Ah, and 160.3 mAh g^-1 (per the Ni-Fe composite), while the #2 prototype cell (dimensions: 50 mm × 50 mm × 335 mm) showed a cell capacity of 49.4 Ah, and 153.2 mAh g^-1 at the 2^nd cycle.

• 방사성폐기물학회지
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• 제20권2호
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• pp.171-183
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• 2022

The parent and daughter nuclides in a radioactive decay chain arrive at secular equilibrium once they have a large half-life difference. The characteristics of this equilibrium state can be used to estimate the production time of nuclear materials. In this study, a mathematical model and algorithm that can be applied to radio-chronometry using the radioactive equilibrium relationship were investigated, reviewed, and implemented. A Bateman equation that can analyze the decay of radioactive materials over time was used for the mathematical model. To obtain a differential-based solution of the Bateman equation, an algebraic numerical solution approach and two different matrix exponential functions (Moral and Levy) were implemented. The obtained result was compared with those of commonly used algorithms, such as the Chebyshev rational approximation method and WISE Uranium. The experimental analysis confirmed the similarity of the results. However, the Moral method led to an increasing calculation uncertainty once there was a branching decay, so this aspect must be improved. The time period corresponding to the production of nuclear materials or nuclear activity can be estimated using the proposed algorithm when uranium or its daughter nuclides are included in the target materials for nuclear forensics.

• Membrane and Water Treatment
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• 제13권6호
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• pp.321-335
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• 2022

Copper-based Metal-organic framework (MOF) namely ([Cu (INA)₂]-MOF) is synthesized by ball milling and characterized using scanning electron microscopy (SEM) for the topography, microstructure, and elemental evidence determination, powdered X-ray diffraction (XRD) for the crystallinity measurement, thermogravimetric (TG) analysis was performed to determine the thermal stability of the material, and Fourier transformed infrared (FTIR) spectroscopy for functional groups identification. The use of [Cu (INA)₂]-MOF as hazardous removal material of β-agonists as persistent hazardous micro-pollutants in our environmental water is first reported in this study. The removal efficiency of the Cu-MOF is successfully determined to be 97.7% within 40 minutes, and the MOF has established an exceptional removal capacity of 835 mg L^-1 with 95 % percent removal on Clenbuterol (CLB) even after the 5th consecutive cycle. The Langmuir model of the adsorption isotherms was shown to be more favourable, while the pseudo-second-order model was found to be favoured in the kinetics. The reaction was exothermic and spontaneous from a thermodynamic standpoint, and the higher temperatures were unfavourable for the adsorption study of the CLB. As a result, the studied MOF have shown promising properties as possible adsorbents for the removal of CLB in wastewater.

• 조명전기설비학회논문지
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• 제26권9호
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• pp.40-46
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• 2012

The single-phase switched reluctance motor(SRM) has only one inductance variation and the positive torque is generated in the restricted section. So, it cannot be started by itself. To solve this problem, many researchers have addressed the several starting method for the single-phase SRM. This paper is focused on the torque characteristics of the single-phase SRM according to starting method. The four major starting method - permanent magnet, saturable stator pole, to grade the rotor, stepped rotor pole - is selected to analyze the torque characteristics. The analysis model of each starting method is designed to changed the pole shape or inserting other material in the basic model. The torque characteristics of each analysis model is obtained by using FEM analysis. The FEM analysis is performed at incremental rotor positions over half inductance cycle in any one pole with 250AT, 500AT, 750AT. The distortion factor of each analysis model is analyzed through the FFT to compare the distortion between basic model and four analysis model.

• Journal of Welding and Joining
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• 제33권3호
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• pp.62-67
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• 2015

A very large shell-structure built in shipyards like ship hulls or offshore structures are joined by welding through full process. As the welding contains a high thermal cycle at a local area, the welded structures should be distorted unavoidably. Because a distorted ship block should be revised to the designed value before the next stage, the ability to predict and to control the weld distortion is an accuracy level of the yard itself. Despite the ship block size, several present thermal distortion methodologies can deal those sizes, but it is a different story to deal full ship size model. Even a fully constructed ship hull not remaining any welding can have an accuracy issue like outfitting installation problems. Any present thermal distortion methodology cannot accept this size for its recommended element size and the number. The ordinary welding breadth at erection stage is about 20~40 mm. It can hardly be a good choice to make finite element model of these sizes considering human effort and computational environment. The finite element model for structure analysis of a ship hull is prepared at front-end engineering design stage which is the first process of the project. The element size of the model is as fine as the longitudinal space, and it is not proper to obtain a weld distortion at the erection stage. In this study, a methodology is suggested that a weldment can be shrunk at original place instead of using structural finite element model. We cut the original shell elements at erection weld-line and put truss elements between the edges of cut elements for weld shrinkage. Additional truss elements are used to facsimile transverse weld shrinkage which cannot be from the weld-line truss element shrink. They attach to weld-line truss element like twigs from barks. The capacity of developed elements is verified through an accuracy check of erection process of a container vessel at the apt. hull. It can be a useful tool for verifying a centering accuracy after renew and for block-separating planning considering accuracy.

• 한국산학기술학회논문지
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• 제22권2호
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• pp.802-809
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• 2021

노후화로 인해 급증하는 유지관리 비용에 대응하기 위하여 자산관리적 관점에서 교량의 유지관리 비용 예측은 필수적이다. 교량의 유지관리 비용 예측은 교량 상태에 기반하여 생애주기비용을 지표로 수행되며, 일반적으로 교량 상태는 열화환경, 하중조건, 재료특성 등에 따라 상당히 넓은 분포특성을 가진다. 본 논문에서는 교량 상태에 영향을 주는 변수로 사용수명, 열화속도, 점검오차를 활용하는 상태예측모델을 활용하여 교량 상태가 생애주기비용 산정에 미치는 영향을 평가하였다. 검토된 변수 중에서 점검오차가 특히 생애주기비용 산정에 상당한 영향을 미치는 것을 확인하였다. 그리고 실제 고속도로 교량의 건전도지수 분포를 기반으로 상하한을 모사하는 상태예측모델을 구축하여 개별 교량에서 발생가능한 생애주기비용의 상하한 값을 추정하였다. 상태예측모델과 연계하여 생애주기동안 발생하는 비용을 예측하기 위해 교량 건전도지수에 따른 보수보강비용 산정식을 활용하였다. 분석을 통해 교량의 상태에 따라 생애주기비용의 차이가 상당히 크게 발생함을 확인하였다. 이에 따라 기존의 평균을 모사하는 단일모델로는 효율적 관리가 어려울 수 있으므로, 향후 다양한 종류의 상태예측모델을 구축하여 교량에 따라 적합한 모델을 적용하는 등 개별 교량의 유지관리 비용 예측신뢰도를 높이기 위한 연구가 필요하다.

• 국제학술발표논문집
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• The 4th International Conference on Construction Engineering and Project Management Organized by the University of New South Wales
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• pp.213-220
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• 2011

In the current construction industry where various stakeholders take part, BIM Data exchange using standard format can provide a more efficient working environment for related staffs during the life-cycle of the building. Currently, the formats used to exchange the data from 3D-CAD application to structure energy analysis at the design stages are IFC, the international standard format provided by IAI, and gbXML, developed by Autodesk. However, because of insufficient data compatibility, the BIM data produced in the 3D-CAD application cannot be directly used in the energy analysis, thus there needs to be additional data entry. The reasons for this are as follows: First, an IFC file cannot contain all the data required for energy simulation. Second, architects sometimes write material names on the drawings that are not matching to those in the standard material library used in energy analysis tools. DOE-2.2 and Energy Plus are the most popular energy analysis engines. And both engines have their own material libraries. However, our investigation revealed that the two libraries are not compatible. First, the types and unit of properties were different. Second, material names used in the library and the codes of the materials were different. Furthermore, there is no material library in Korean language. Thus, by comparing the basic library of DOE-2, the most commonly used energy analysis engine worldwide, and EnergyPlus regarding construction materials; this study will analyze the material data required for energy analysis and propose a way to effectively enter these using semantic web's ontology. This study is meaningful as it enhances the objective credibility of the analysis result when analyzing the energy, and as a conceptual study on the usage of ontology in the construction industry.