• Advances in concrete construction
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• 제12권5호
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• pp.377-389
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• 2021

Reinforced concrete vertical silos are universal structures that store large amounts of granular materials. Due to the asymmetric structure, heavy load, uneven storage material distribution, and the difference between the storage volume and the storage material bulk density, the corresponding earthquake is very complicated. Some scholars have proposed the calculation method of horizontal forces on reinforced concrete vertical silos under the action of earthquakes. Without considering the effect of torsional effect, this article aims to reveal the expansion factor of the silo group considering the torsional effect through experiments. Through two-way seismic simulation shaking table tests on reinforced concrete column-supported group silo structures, the basic dynamic characteristics of the structure under earthquake are obtained. Taking into account the torsional response, the structure has three types of storage: empty, half and full. A comprehensive analysis of the internal force conditions under the material conditions shows that: the different positions of the group bin model are different, the side bin displacement produces a displacement difference, and a torsional effect occurs; as the mass of the material increases, the structure's natural vibration frequency decreases and the damping ratio Increase; it shows that the storage material plays a role in reducing energy consumption of the model structure, and the contribution value is related to the stiffness difference in different directions of the model itself, providing data reference for other researchers; analyzing and calculating the model stiffness and calculating the internal force of the earthquake. As the horizontal side shift increases in the later period, the torsional effect of the group silo increases, and the shear force at the bottom of the column increases. It is recommended to consider the effect of the torsional effect, and the increase factor of the torsional effect is about 1.15. It can provide a reference for the structural safety design of column-supported silos.

• Structural Engineering and Mechanics
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• 제48권6호
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• pp.809-822
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• 2013

Base isolation is widely used in seismic resisting buildings due to its low construction cost, high reliability, mature theory and convenient usage. However, it is difficult to design the isolation layer in high-rise buildings using the available bearings because high-rise buildings are characterized with long period, low horizontal stiffness, and complex re-distribution of the internal forces under earthquake loads etc. In this paper, a simple and innovative isolation bearing, named Teflon-based lead rubber isolation bearing, is developed to address the mentioned problems. The Teflon-based lead rubber isolation bearing consists of friction material and lead rubber isolation bearing. Hence, it integrates advantages of friction bearings and lead rubber isolation bearings so that improves the stability of base isolation system. An experimental study was conducted to validate the effectiveness of this new bearing. The effects of vertical loading, displacement amplitude and loading frequency on the force-displacement relationship and energy dissipation capacity of the Teflon-based lead rubber isolation bearing were studied. An analytical model was also proposed to predict the force-displacement relationship of the new bearing. Comparison of analytical and experimental results showed that the analytical model can accurately predict the force-displacement relationship and elastic shear deflection of the Teflon-based lead rubber isolation bearings.

• 전자공학회논문지
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• 제49권9호
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• pp.293-299
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• 2012

전기 임피던스 단층촬영법은 대상체의 표면에 부착된 전극들을 통해 전류를 주입하고 전압을 측정함으로써, 내부의 도전율 또는 저항률 분포를 추정하고 영상으로 복원하는 비교적 새로운 영상 복원 기법이다. 이 논문에서는 on-line에서 한 번의 연산으로도 표적의 정확한 위치 정보와 복원의 정확도를 향상시킬 수 있는 새로운 역문제 알고리즘을 개발하였다. 그리고 제안한 방법의 복원 성능을 향상시키기 위해 가중 행렬의 고유치로부터 step-length를 계산하였다. 몇 가지 시나리오를 설정하고 모의실험을 통해 제안한 방법의 영상 복원의 성능을 평가하였다.

• 대한기계학회논문집B
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• 제41권10호
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• pp.667-673
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• 2017

공개소스 전산유체 해석 라이브러리인 OpenFOAM을 이용하여 음극 지지체형 고체산화물 연료전지의 온도균일성에 관한 연구를 수행하였다. 3가지 유형의 유동흐름(병행류, 대향류, 직교류)에 대하여 수치해석이 이루어졌다. 다공성 물질내에서의 기체의 흐름은 유효확산계수를 이용하여 계산하였고 분리판의 리브 영향도 고려하였다. 전기화학반응의 계산을 위하여 실험식으로부터 얻은 집중내부저항 모델이 사용되었다. 수치해석 결과 대향류가 가장 균일한 온도분포를 나타내었다.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2009년도 춘계학술대회 논문집
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• pp.731-734
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• 2009

KIER has been developed a compact and highly efficient fuel processor which is one of the key component of the residential PEM fuel cells system. The fuel processor uses methane steam reforming to convert natural gas to a mixture of water, hydrogen, carbon dioxide, carbon monoxide and unreacted methane. Then carbon monoxide is converted to carbon dioxide in water-gas-shift reactor and preferential oxidation reactor. A start-up time of the fuel processor is about 1h and CO concentration among the final product is maintained less than 5 vol. ppm. To achieve high thermal efficiency of 80% on a LHV basis, an optimal thermal network was designed. Internal heat exchange of the fuel processor is so efficient that the temperature of the reformed gas and the flue gas at the exit of the fuel processor remains less than $100^{\circ}C$. A compact design considering a mixing and distribution of the feed was applied to reduce the reactor volume. The current volume of the fuel processor is 17L with insulation.

• 한국응용과학기술학회지
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• 제15권4호
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• pp.11-20
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• 1998

The propagation of light radiation in a turbid medium is an important problem that confronts dosimetry of therapeutic laser delivery and the development of diagnostic spectroscopy. Scattered light is measured as a function of the position(distance r, depth z) between the axis of the incident beam and the detection spot. Turbid sample yields a very forward-directed scattering pattern at short range of position from source to detector, whereas the thicker samples greatly attenuated the on-axis intensity at long range of position. The portions of scattered light reflected from or transmitted throughphantom depend upon internal reflectance and absorption properties of the phantom. Monte Carlo simulation method for modelling light transport in tissue is applied. It uses the photon is moved a distance where it may be scattered, absorbed, propagated, internally reflected, or transmitted out of tissue. The photon is repeatedly moved until it either escape from or is absorbed by the phantom. In order to obtain an optimum therapeutic ratio in phantom material, optimum control the light energy fluence rate is essential. This study is to discuss the physical mechanisms determining the actual light dose in phantom. Permitting a qualitative understanding of the measurements. It may also aid in designing the best model for laser medicine and application of medical engineering.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2008년도 추계학술대회 논문집 Vol.21
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• pp.268-269
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• 2008

Charging of spacecraft occurs in plasma and radiation environment. Especially, we focused on an accident caused by internal charging in a glass material that was used as the cover plate of solar panel array, and tried to measure the charge distribution in glass materials under electron beam irradiation by using a PEA (Pulsed Electro-Acoustic method) system. In the case of a quartz glass (pure $SiO_2$), no charge accumulation was observed either during or after the electron beam irradiation. On the contrary, positive charge accumulation was observed in glass samples containing metal-oxide components. It is found that the polarity of the observed charges depends on the contents of the impurities. To identify which impurity dominates the polarity of the accumulated charge, we measured charge distributions in several glass materials containing various metal-oxide components and calculated the trap energy depths from the charge decay characteristics of all glass samples.

• 전기전자학회논문지
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• 제19권3호
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• pp.407-414
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• 2015

전기 임피던스 단층촬영 기법은 대상체 표면의 전극들을 통해 주입시킨 전류 데이터와 이에 유기되는 측정 전압 데이터를 기반으로 내부의 도전율 분포를 가시화하는 기법이다. 이 논문에서는 완전전극 모델을 사용한 해석적 방법의 해법을 유도하고 전압을 계산하였다. 그리고 기존의 수치적 해법인 유한 요소법과 경계 요소법을 사용하여 전압 데이터를 또한 계산하였다. 배경이 균질한 경우와 비균질한 경우에 대해 각 정문제 해법의 해를 실험 데이터 와 비교하였다. 그리고 평균 제곱근 오차를 계산하여 정문제 해법들의 오차를 비교분석하였다.

• 한국안전학회지
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• 제26권2호
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• pp.26-31
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• 2011

In this paper, the safety diagnosis using thermal image analysis is described for power equipments. The conventional three-phase comparison method has only provided the results of thermal comparison for the equipments. The proposed method defines the conditions of poor connection by visual checks, and supports the criteria with each thermal rise step. As a result, the thermal difference from $5^{\circ}C$ to $10^{\circ}C$ meant the warning state. In addition, the thermal difference more than $10^{\circ}C$ meant that the connection status was unbalanced. In this case, the countermeasure might be the internal load distribution. If the thermal difference more than $20^{\circ}C$ is observed, it means a hot spot at the poor connection. If the hot spot is observed all over the surface, its cause was the unbalanced load, which made the conductive parts discolored and raised the possibility of oxidization or $Cu_2O$ generation. This diagnostic technology employing thermal image analysis method can be directly applied in the field and ensures the safety of equipments.

• 설비공학논문집
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• 제17권4호
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• pp.377-385
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• 2005

An analytical model was developed using the lumped mass parameter method to estimate temperature distribution of metal parts and refrigerant of the hermetic reciprocating compressor, All of the lumped mass has been equated with the first law of thermodynamics. In the delivered equation, correlations of heat transfer coefficient in the heat transfer equation were taken from open literature. The equations are solved by Gauss-Jordan method simultaneously. To verify the developed numerical program, an experiment was conducted with a domestic refrigerator. The compressor which had been installed at the bottom of the experimental refrigerator was modified to measure internal temperature. Model verification test was conducted at $30^{\circ}C$ outdoor temperature with variation of compressor cooling conditions. As a result, there is a good consistency between calculated temperature and measured one.