• 한국전기전자재료학회논문지
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• 제36권4호
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• pp.391-396
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• 2023

Recently, as power and electronic devices have increased in frequency and capacity, it has become a major concern to protect electronic circuits and electronic components used in these devices from abnormal voltages such as various surges and pulse noise. To respond to variously rated voltages applied to power electronic devices, the rated voltages of various varistors can be obtained by controlling the size of internal particles of the varistor or controlling the number of layers of the varistor. During bonding, the problem of unbalanced thermal runaway occurring between the electrode and the varistor interface causes degradation of the varistor and shortens its life of the varistor. In this study, to solve the problem of unbalanced heat distribution of stacked varistors to adjust the operating voltage, the contents of the ZnO-based varistor composition were 96 wt% ZnO, 1 mol% Sb₂O₃, 1 mol% Bi₂O₃, 0.5 mol% CoO, 0.5 mol% MnO, and 1 mol% TiO₂. A multi-layered ZnO varistor was modeled by bonding a single varistor with a composition in three layers according to the operating voltage. The thermal distribution of the triple-layered ZnO varistor was analyzed for the thermal runaway phenomenon that occurred during varistor operation using the finite element method according to Comsol 5.2.

• 박물관보존과학
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• 제21권
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• pp.53-66
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• 2019

본 연구는 강원도 영월 하송리 유적에서 출토된 금속유물의 보존처리 과정과 표면성분분석 결과를 제시하였다. 금동소형풍탁 1점, 풍설 2점, 호리병 형태 소형 청동병 1점을 대상으로 XRF를 이용한 표면 성분분석을 진행하였고, 호리병 형태 소형청동병은 X-ray를 통한 내부구조관찰을 실시하였다. 금동소형풍탁과 풍설은 같은 위치에서 출토되었으나, 금동소형풍탁은 도금층이 확인되는데 반해, 풍설은 부식층이 표면에 고착되어 가시적으로 확인되지 않았다. 분석결과 금동소형풍탁은 Cu-Sn-Pb 3원계 합금 청동소지에 Au를 수은 아말감으로 도금하여 제작하였음을 확인하였다. 풍설은 소지가 구리이며, 소량의 금성분이 검출되었다, 호리병 형태 소형 청동병은 형태적으로 비슷한 고려시대 화폐인 은병(銀甁)인지 여부를 확인하고자 표면 성분분석과 함께 X-ray 촬영을 실시하였다. X-ray 촬영 결과 저부의 가운데 부분에 작은 구멍을 막았던 것으로 보이는 흔적이 확인되었으며, 전체적인 표면분석 결과에서는 은이 검출되지 않아 은병이 아닌 청동유물임을 알 수 있었다.

• The Journal of Advanced Prosthodontics
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• 제7권1호
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• pp.56-61
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• 2015

PURPOSE. The purpose of this study was to evaluate the effects of the surface treatment and shape of the dental alloy on the composition of the prosthetic work and its metallic ion release in a corrosive medium after casting. MATERIALS AND METHODS. Orion Argos (Pd-Ag) and Orion Vesta (Pd-Cu) were used to cast two crowns and two disks. One of each was polished while the other was not. Two as-received alloys were also studied making a total of 5 specimens per alloy type. The specimens were submersed for 7 days in a lactic acid/sodium chloride solution (ISO standard 10271) and evaluated for surface structure characterization using SEM/EDAX. The solutions were quantitatively analysed for the presence of metal ions using ICP-MS and the results were statistically analysed with one-way ANOVA and a Tukey post-hoc test. RESULTS. Palladium is released from all specimens studied (range $0.06-7.08{\mu}g{\cdot}cm^{-2}{\cdot}week^{-1}$), with the Pd-Cu alloy releasing the highest amounts. For both types of alloys, ion release of both disk and crown pairs were statistically different from the as-received alloy except for the Pd-Ag polished crown (P>.05). For both alloy type, disk-shaped pairs and unpolished specimens released the highest amounts of Pd ions (range $0.34-7.08{\mu}g{\cdot}cm^{-2}{\cdot}week^{-1}$). Interestingly, in solutions submerged with cast alloys trace amounts of unexpected elements were measured. CONCLUSION. Shape and surface treatment influence ion release from dental alloys; polishing is a determinant factor. The release rate of cast and polished Pd alloys is between $0.06-0.69{\mu}g{\cdot}cm^{-2}{\cdot}week^{-1}$, which is close to or exceeding the EU Nickel Directive 94/27/EC compensated for the molecular mass of Pd ($0.4{\mu}g{\cdot}cm^{-2}{\cdot}week^{-1}$). The composition of the alloy does not represent the element release, therefore we recommend manufacturers to report element release after ISO standard corrosion tests beside the original composition.

• 문화기술의 융합
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• 제8권3호
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• pp.313-321
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• 2022

5G기술의 발전과 함께 실감형 콘텐츠에 대한 관심이 커지고 있다. 영화 속에서나 가능했던 홀로그램과 같은 실감형 콘텐츠가 현실에서도 구현될 것이라는 전망이 나오고 있다. 1948년 데니스 가버가 기본 이론을 발표한 이후로 오랜 기간 연구되어 온 홀로그램 분야도 디지털 기술을 접목하여 새로운 방향으로 발전을 계속하고 있다. 빛의 간섭패턴을 기록하여 제작하는 전통적인 광학식 홀로그램으로부터 컴퓨터 형성 홀로그램 (computer generated hologram, CGH)과 디지털 홀로그램 프린터 분야로 발전하고 있다. 디지털 홀로그램 프린터를 이용해 홀로그램을 제작하기 위해서는 우선 여러 장의 다시점 이미지를 이용하여 호겔 (holographic element, Hogel) 이미지를 생성해야 한다. 연속된 다시점의 이미지를 획득하는 방법으로는 실사를 직접 촬영하는 방법과 3D 그래픽 제작 도구를 이용하여 오브젝트를 모델링하고 가상 카메라의 움직임을 렌더링하는 방법이 각각 사용되고 있다. 본 논문에서는 새로운 이미지 획득 방법으로 시각효과 (visual effect, VFX) 기법 중 한 가지인 크로마키 합성 기술을 이용해 다시점 이미지를 제작하는 방법을 제안한다. 실사를 그린 스크린 위에 배치하여 촬영하고, 3D 컴퓨터 그래픽 (comuter graphic, CG) 배경과 합성을 하는 전체 워크플로우를 제시하고, 각 단계의 역할을 설명한다. 제시된 워크플로우의 전체나 일부를 응용하면 추후 새로운 이미지 획득 방법을 연구하는 데에 도움이 될 것으로 기대한다.

• Journal of Ship and Ocean Technology
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• 제3권2호
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• pp.27-48
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• 1999

The paper is concerned with application to develop the expert system, which structural analysis and design process for tower cranes. The system is organized into three groups. One is pre-processor for creating input data files, another is `model former' which combines knowledge-base with inference engine for automatic generating structural analysis models, a third is application group for final analysis checks. In this study, geometric subroutine of `model former' designates node positions, nodes, elements numbers and element types. Load data subroutine computes weight of tower crane and device, slewing force, cargo load, wind force form rules or equations in knowledge-base. Also, Property and boundary subroutine applies element properties and boundary conditions to suitable elements and nodes. Design and analysis expert system for tower crane integrates these subroutine, `model former' and pre-processor. RBR(Rule-Base Reasoning) was adopted for a reasoning strategy of this expert system. And this expert system can produce structural analysis model and data, which can be used in ordinary structural analysis program (SAP, ADINA or NASTRAN, etc.). In this paper, this expert system produces format of the analysis model data, which are used in MSC/NASTRAN. The main discussions included in the paper are introduction of the tower crane and structural analysis, composition of the design expert system for tower crane and structural analysis using the expert system.

• Steel and Composite Structures
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• 제20권4호
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• pp.813-832
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• 2016

This research deals with the behavior of Composite Box Girder Bridges (CBGBs) subjected to environmental effects such as solar radiation, atmospheric temperature, and wind speed. It is based on temperature and thermal stress results, which were recorded hourly from a full-scale experimental CBGB segment and Finite Element (FE) thermal analysis. The Hemi-cube method was adopted to achieve the accuracy in temperature distributions and variations in a composition system during the daily environmental variations. Analytical findings were compared with the experimental measurements, and a good agreement was found. On the other hand, parametric investigations are carried out to investigate the effect of the cross-section geometry and orientation of the longitudinal axis of CBGB on the thermal response and stress distributions. Based upon individual parametric investigations, some remarks related to the thermal loading parameters were submitted. Additionally, some observations about the CBGB configurations were identified, which must be taken into account in the design process. Finally, this research indicates that the design temperature distribution with a uniform differential between the concrete slab and the steel girder is inappropriate for describing the thermal impacts in design objective.

• 한국실내디자인학회논문집
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• 제19권5호
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• pp.38-47
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• 2010

The purpose of this study is to examine the characteristics by design component elements of the facade in elementary school buildings after the 7th educational curriculum. This study choose twenty five elementary school as the subjects of the study. And among many elevations of building, an elevation that is alongside of the schoolyard is chosen because this elevation has the highest visual influence on passers-by. To begin with, this elevation is divided into the roof and the surface of a wall, The roof is divided into roof styles, existence of roof and materials. The surface of a wall is divided into design principles(balance, contrast, rhythm), the formal organization(basic elements and form, and transformation of form), the ornamental composition, materials and colors. The results of the research are summarized as follows: First of all, motifs of classical architecture were well expressed in this period and postmodern tendency had been shown until 2005. After Build Transfer Lease(BTL), however, tendency of classical architecture, contrast by the size of the form and base element by point disappeared. Instead, asymmetrical and flat tendency is expressed. Also, emphasized design of the building elevation appear by basic colors of Munsell, not motifs of classical architecture.

• 한국태양에너지학회:학술대회논문집
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• 한국태양에너지학회 2009년도 춘계학술발표대회 논문집
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• pp.43-48
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• 2009

In this study, through case studies, solar energy systems were coordinated with architectural plan elements and the others in apartment complex, and the energy performance was evaluated quantitatively through computer simulation PVSYST and RETScreen. As a results, in plan process of the application of solar energy systems in apartment complex, solar energy system should be considered as not only energy reducing technical element but also part of architectural plan element. And it must be considered with architectural plan elements, composition methods, energy storage methods, technical elements from the early basic plan stage. Photovoltaic system was installed on the wall facing the south and rooftop. The energy ratio of electric load was shown to be 5.5%. The result showed 7.2% when adding it to shading device additionally, and 6.4% in case of putting extra translucent module on windows. Active solar collecting system was applied on roof with the angle of 45. Maximum number of solar collector was 10 in a row, and the total solar collecting area was $915.00m^2$. The energy ratio of domestic water heating load by active solar hot water system is shown to be 11.4%.

• KIEAE Journal
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• 제16권3호
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• pp.35-46
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• 2016

Purpose: This paper aims to analyse the composition system of architectural elements including shape, kinetic and material elements of kinetic facades and establish the design parameter system as a common conceptual and practical knowledge sharing platform with mechanical and electrical experts. Method: This research has been conducted in a three steps. At first, 120 cases of external shading devices are analyzed and their classification criteria have been established. Secondly geometric, kinetic and material elements are categorized in a common kinetic facade coordinates system considering environmental effects and operation method, and the applicability of combination of each element are tested. Lastly core design parameters for each element have been established in a common office building installation coordinate. Result: Geometry elements are categorized into seven geometric shapes and kinetic elements is categorized into basic linear and rotational motion and combinational folding and rolling motion. The combined set of parameters for three elements composes the whole design parameters for architectural elements of kinetic façade. Design parameters of shape elements are composed of shape, installation and arrangement parameters; design parameters for kinetic elements are composed of axis and range parameters; and design parameters of material elements are composed of thermal, lighting and color parameters.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2009년도 춘계학술대회 논문집
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• pp.334-336
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• 2009

An elastic-plasticity model during the austenitic decomposition was derived and implemented to incorporate the two important deformation behaviors observed during the phase transformations: the volumetric strain and transformation induced plasticity due to the temperature change and phase transformation. To obtain transformed phase volume fractions during cooling, the fourth order Runge-Kutta method was used to solve the Kirkaldy's phase kinetics model which is function of temperature, austenitic grain size and chemical composition. The volumetric strain was calculated by considering the densities of constituent phases, while the transformation induced plasticity was based on the micro-plasticity due to the volume mismatch between soft austenitic phase and other harder phases. The constitutive equations were implemented into the implicit finite element software and a simple boundary value problem was chosen as a model problem to validate the effect of transformation plasticity on the deformation behavior of steel under cooling from high temperature. It was preliminary concluded that the transformation plasticity plays a critical role in relaxing the developed stress during forming and thus reducing the magnitude of springback.