• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 제36회 하계학술대회 논문집 B
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• pp.1059-1061
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• 2005

The bushing currently applied to pole-mounted type loadbreak switch has porcelain bushing which is connected with the mold cone. This type has potential problems of uncertainty of sealing of the interface part and gas leakage on the connected part between bushing and switch tank due to the weight of the porcelain. The Composite Bushing can solve these problems and also the secondary problem of the potential accident owing to the fragment of the porcelain bushing in breakage due to the outer impact.

• Composites Research
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• 제28권6호
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• pp.383-388
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• 2015

이온성 고분자 복합물인 IPMC(Ionic Polymer Metal Composite)는 부드러운 고분자 필름의 양면에 백금으로 구성된 전극층이 부착된 형태로 구성되어 있으며, 외부 물리적 자극에 대응하여 전기적 에너지를 발생시키는 특성을 가지고 있다. 본 논문에서는 IPMC의 굽힘에 대응하여 생성되는 전압을 예측할 수 있는 회로 모델을 제안하였다. 모델의 내부는 IPMC의 물리적인 특성을 묘사하는 전기 소자들로 구성되어 있으며, 실제 측정된 출력 전압과 시뮬레이션 출력 전압 사이의 RMS(Root Mean Square) 오차가 최소화 되도록 파라미터들의 값이 선정되었다. 이어서, 회로 모델의 관측기를 극점 배치 기법을 사용하여 설계하였으며 관측기로부터의 출력 전압 시뮬레이션의 결과 실제 전압 신호와의 오차가 줄어듦을 확인하였다. 또한, 상태 관측기 설계 기법이 측정된 출력 전압으로부터 입력 굽힘 각도를 추정하는 역 모델의 설계에도 적용되었으며 설계된 역 모델이 입력 각도를 큰 오차 없이 추정함을 검증하였다.

• Steel and Composite Structures
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• 제36권2호
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• pp.229-247
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• 2020

This study analyzed stresses in concrete and its reinforcement, computing the additional loading transferred by concrete creep. The loading varied from zero, structure exclusively under its self-weight, up to the critical buckling load. The studied structure was a real, tapered, reinforced concrete pole. As concrete is a composite material, homogenizing techniques were used in the calculations. Due to the static indetermination for determining the normal forces acting on concrete and reinforcement, equations that considered the balance of forces and compatibility of displacement on cross-sections were employed. In the mathematical solution used to define the critical buckling load, all the elements of the structural dynamics present in the system were considered, including the column self-weight. The structural imperfections were linearized using the geometric stiffness, the proprieties of the concrete were considered according to the guidelines of the American Concrete Institute (ACI 209R), and the ground was modeled as a set of distributed springs along the foundation length. Critical buckling loads were computed at different time intervals after the structure was loaded. Finite element method results were also obtained for comparison. For an interval of 5000 days, the modulus of elasticity and critical buckling load reduced by 36% and 27%, respectively, compared to an interval of zero days. During this time interval, stress on the reinforcement steel reached within 5% of the steel yield strength. The computed strains in that interval stayed below the normative limit.

• Advances in aircraft and spacecraft science
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• 제6권2호
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• pp.169-187
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• 2019

This work presents a practical detailed finite element (FE) approach for the three-dimensional (3D) free-vibration analysis of actual aircraft and spacecraft-type lightweight and thin honeycomb sandwich panels. It consists of calling successively in $MATLAB^{(R)}$, via a developed user-friendly GUI, a detailed 3D meshing tool, a macrocommands language translator and a commercial FE solver($ABAQUS^{(R)}$ or $ANSYS^{(R)}$). In contrary to the common practice of meshing finely the faces and core cells, the proposed meshing tool represents each wall of the actual hexagonal core cells as a single two-dimensional (2D) 4 nodes quadrangularshell element or two 3 nodes triangular ones, while the faces meshes are obtained simply using the nodes at the core-faces interfaces. Moreover, as the same 2D FE interpolation type is used for meshing the core and faces, this leads to an automatic handling of their required FE compatibility relations. This proposed approach is applied to a sample made of very thin glass fiber reinforced polymer woven composite faces and a thin aluminum alloy hexagonal honeycomb core. The unknown or incomplete geometric and materials properties are first collected through direct measurements, reverse engineering techniques and experimental-FE modal analysis-based inverse identification. Then, the free-vibrations of the actual honeycomb sandwich panel are analyzed experimentally under different boundary conditions and numerically using different mesh basic cell shapes. It is found that this approach is accurate for the first few modes used for pre-design purpose.

• 한국결정성장학회지
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• 제5권4호
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• pp.343-350
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• 1995

$\alpha$ - 및 $\beta$-SiC를 출발원료로 하여 일축성형한 후 $1800^{\circ}C$에서 고온가압법으로 소결한 탄화규소에 나타난 우선방위의 정도를 X-ray pole figure analysis로 조사하였다. $\alpha$-SiC를 출발원료로 사용한 경우에 고온 가압소결 후 약한 집합조직을 보인 반면, $\beta$ - SiC를 출발원료로 사용한 경우 고온가압소결 후 강한 집합조직을 보였으며, 이 경우 ${\beta} {\rightarrow} {\alpha}$ 상변태에 기인한 이중미세구조를 나타내었다. 또한, 집합조직의 강도는 고온가압소결 후 행해진 열처리 조건에 따라서도 변화를 보였다.

• 대한기계학회논문집A
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• 제33권5호
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• pp.482-488
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• 2009

Dancer system is typically used equipment for attenuation of tension disturbances. In industrial converting machines, a composite type of dancer system is applied which is mixture of active and passive dancer. It includes feedback position control loop of roll with pendulum dancer and its characteristics is different from passive and active one. In this paper, a mathematical model of the pendulum dancer was derived including PI position feedback controller and it was analyzed by using a pole-zero map and bode plot under various conditions. It was found out that velocity, length of span and inertia were associated with the performance of regulation. It was suggested that the length of upstream span should be greater than that of the downstream and the inertia should be smaller for improvement of the performance. The results can be used for design guidelines of the industrial dancer system.

• 한국콘텐츠학회:학술대회논문집
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• 한국콘텐츠학회 2016년도 춘계 종합학술대회 논문집
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• pp.473-474
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• 2016

본 연구에서는 흉물스러운 외관으로 도심의 애물단지로 전락해버린 전주에 대한 인식을 변화시키기 위해 문화콘텐츠 관점에서 전주 디자인을 제시하였다. 여기에서는 문화콘텐츠의 핵심 함의를 대중들과의 경험과 감정의 소통을 긴밀하게 하고, 문화적 의미가 생산 순환하게 하는 창구 역할로 보았다. 이러한 전제 아래 전주 디자인이 가져야 하는 가치 즉, 기능성, 통합성, 연속성, 감응성을 도출하였으며 이를 반영하는 전주 디자인 다섯 가지를 제시하였다.

• 한국정밀공학회지
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• 제26권6호
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• pp.81-89
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• 2009

Dancer systems are typical equipment for attenuation of tension disturbances. Lately, demands for high speed roll-to-roll machines are rising but it is prior to attenuate the tension variation on the web entering into the printing zone to achieve the speed increment. Maintaining a constant tension before the first printing cylinder is the key of high speed, high quality printing. Dancer has been researched in two ways, whether it is controlled or not. The first one is active dancer and the other one is passive dancer. In the active dancer, a position of idle roll of dancer is measured and the roll is moved by external hydraulic cylinder to control tension disturbances. While the passive one composed with spring, damper and idle roll has no external actuator to position the idle roll. The tension disturbance causes movement of dancer roll and the displacement of the roll regulates the tension variation. On the other hand a composite type of dancer is applied for roll-to-roll printing machines. It has same apparatus as passive dancer. The displacement of roll is measured and front(or rear) driven roller is controlled to position the roll. In this paper, it is presented an analysis of pendulum dancer including position feedback PI control and logic for PI gain tuning in roll-to-roll machines. Pole-zero map and root locus with varying system parameters gives a design method for control of the dancer.

• KEPCO Journal on Electric Power and Energy
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• 제5권3호
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• pp.135-140
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• 2019

Lattice towers and tubular steel poles have been commonly used for electrical power transmission in Korea. They are durable, structurally stable, simple and can easily be constructed in limited spaces. However, residents are opposed to construct transmission lattice towers in their areas because they are not visually attractive, and electrical field occur at the transmission lines. Underground transmissions have been used instead of the traditional towers to resolve these problems, however they are not cost effective to construct and run. Therefore, we have developed eco-friendly towers that are more attractive, well blending into the surrounding environment, and much more economical than underground transmissions. There are four categories of the eco-friendly electric transmission towers about design aspects. Firstly, there is decoration type such as tree tower and ensemble tower. Tree tower looks like actual trees with leaves and branches so it blends into surroundings. Ensemble towers were designed after pair of crane birds. Those towers have decoration features and art works. Structural examination and manufacturing this type would be very similar to the conventional transmission towers. Secondly, there is arm design type such as traditional tower. Design features are added to the existing towers. As partial design can be adoptable on these types, it can easily meet height regulations and attach to conventional lattice towers and tubular steel poles. Also, these towers are more economical than others. Third category is multipurpose type such as Sail Tower. These towers have simple pole or tubular structure with features which can be used as information message board, public relations and much more. This type will face greater wind pressure because of the area of the board, also visibility must take into consideration. Lastly, there is moulding type such as arc pylon. It is different shape to the conventional towers - lattice towers and tubular steel poles. Dramatic design changes have been adapted - from a hard and static tower to a soft and curved tower. These towers will well stand out in the field. However, structural examination and manufacturing this type would be difficult and costly. Also certain towers of this type would require scaffolding or false work to construct, which will result in limitations of the construction area. This paper shows KEPCO 154 kV Sail tower in detail. KEPCO 154 kV Sail tower that is included in fabrication of sample tower and tower testing has developed and the results are presented in this paper. We hope that sail tower is also considered as a solution to have public acceptance or to create a familiar atmosphere among towers and people in coastal area.