• Journal of the Earthquake Engineering Society of Korea
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• v.5 no.3
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• pp.37-43
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• 2001

The energy concept has been extended to compare the hysteretic performance between various structural systems. As a result, the energy absorption efficiency is defined as the cumulative energy absorption capacity of a structural system normalized by that of the elasto-perfectly plastic system as a benchmark for comparisons. For this, the construction of energy curves from the experimental results obtained by cyclic loading tests is required. Using the proposed procedure, structures differing from each other in geometry, material and construction can be relatively and objectively compared for seismic performance. Also the beauty of this method is in its irrelevance to the structural failure mode. The proposed procedure was validated by application to the experimental results of two different specimens.

• Korean Journal of Optics and Photonics
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• v.8 no.2
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• pp.122-127
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• 1997

The hexagonal wurtzite structure of CdSe quantum dots are investigated by X-ray diffraction experiment. The absorption peaks due to quantum confinement effect are observed in the linear absorption spectra. Absorption coefficient changes at the lowest transition are measured with pump wavelength at the lowest transition and at the next higher transition from which direct intraband transition is not allowed. The measured larger absorption changes at the lowest transition confirm that the selection rules of intraband transition resulting from quantum confinement effect are satisfied. From the experimental results, therefore, we concluded that the CdSe quantum dots can be described as homogeneous system.

• Journal of the Korean Society of Hazard Mitigation
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• v.9 no.2
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• pp.23-30
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• 2009

Crash cushions are protective devices that prevent errant vehicles from impacting on fixed objects. This function is accomplished by gradually decelerating a vehicle to a safe stop in a relatively short distance. Commonly used crash cushions generally employ one of two concepts to accomplish this function. The first concept involves the absorption of the kinetic energy of a moving vehicle by crushable or plastically deformable materials and the other one involves the transfer of the momentum of a moving vehicle to an expendable mass of material located in the vehicle's path. Crash cushions using the first concept are generally referred to as compression crash cushions and crash cushions using the other concept are generally referred to as inertial crash cushion. The objective of this research is the development of a compression-type crash cushion by employing the two concepts simultaneously. To minimize the number of full-scale crash tests for the development of the crash cushion, preliminary design guide considering inertial and frictional energy absorption was constructed and computer simulation was performed. LS-DYNA program, which is most widely used to analyze roadside safety features, was used for the computer simulation. The developed crash cushion satisfied the safety evaluation criteria for various impact conditions of CC2 performance level in the Korean design guide.

• Applied Chemistry for Engineering
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• v.17 no.1
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• pp.111-117
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• 2006

The improvement of energy conservation mandates decrease consumption of fossil fuels and minimize negative impacts on the environment, which originates from large cooling and heating demand. The absorption heat pump technology has a large potential for energy saving in this respect. Adsorption heat pump is a means to upgrade waste heat without addition of extra thermal energy. The increase of absorbed amount is of great importance for absorption heat pump cycle. In this study, in order to improve the performance of absorber, the absorbers of two different types have been investigated using methanol-glycerine as a working fluid. The former was tangential feed of liquid phase without spiral tube in the absorber and the latter was with spiral tube in the absorber. The latter was found to be more effective in enhancing the mass and heat transfer to increase the absorption performance.

• Composites Research
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• v.26 no.3
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• pp.175-181
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• 2013

The evaluation and prediction for the absorbed energy, residual velocity, and impact damage are the key things to characterize the impact behavior of composite laminated panel subjected to high-velocity impact. In this paper, the method to predict the residual velocity and the absorbed energy of Carbon/Epoxy laminated panel subjected to high velocity impact are proposed and examined by using quasi-static perforation test and high-velocity impact test. Total absorbed energy of specimen due to the high-velocity impact can be grouped with static energy and kinetic energy. The static energy are consisted of energy due to the failure of the fiber and matrix and static elastic energy, which are related to the quasi-static perforation energy. The kinetic energy are consisted of kinetic energy of moving part of specimen, which are modelled by three modified kinetic model. The high-velocity impact test were conducted by using air gun impact facility and compared with the predicted values. The damage area of specimen were examined by C-scan image. In the high initial impact velocity above the ballistic limit, both the static energy and the kinetic energy are known to be the major contribution of the total absorbed energy.

• Journal of the Korean Society for Marine Environment & Energy
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• v.10 no.3
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• pp.173-180
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• 2007

Oscillating wave amplitude in a bottom-mounted OWC chamber designed for wave energy converter is investigated by applying characteristic wave conditions in Korean coastal water. The effects of shape parameters of OWC chamber in a view of wave energy absorbing capability are analyzed. Both experimental and numerical approaches are adopted and their results are compared to optimize the shape parameters which can result in a maximum power production under given wave distribution. The experiment was carried out in a wave flume under 2-D assumption of OWC chamber. The numerical scheme employed a hybrid Green integral equation which adopts the Rankine Green function inside chamber to take account of fluctuating air pressure, while it uses the Kelvin Green function in outer domain. Air duct diameter, chamber width, and submerged depths of front skirt and back wall of chamber changes the magnitude and peak frequency of wave absorption significantly.

• The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
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• v.33 no.3
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• pp.24-28
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• 2004

흡수식 2중 효용 냉온수기의 개발 현황을 소개하고자 하며, 흡수식 관련 연구개발이 보다 활성화되는 방향을 제시하고자 한다. 하절기 및 동절기의 중대형 빌딩의 냉난방 부하 대응에 흡수식 냉온수기가 차지하고 있는 비율이 높음으로 흡수식 냉온수기의 고효율화가 경제 및 산업적으로 건물 에너지 절감 및 국가 전체 가스 에너지 절약에 미치는 파급 효과는 매우 크다. 흡수식냉동기는 근본적으로 오존파괴의 문제가 없는 냉매를 사용하고 있고, 고급연료인 LNG를 주로 사용하고 있기 때문에, 지구온난화 유발물질인 $CO_2$ 배출량이 다른 연료에 비해 작다. 아울러 극소량의 공해물질(Nox, Sox)을 방출하며 공해문제를 별로 발생시키지 않기 때문에 흡수식냉동기의 연구개발을 거의 하지 않은 서방 선진국에서도 환경친화적인 흡수식 제품에 대한 관심이 최근에 급증하고 있다.(중략)

• Composites Research
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• v.35 no.6
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• pp.469-476
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• 2022

In this paper, the microwave absorbing characteristics after the impact of the radar-absorbing structure (RAS) consisting of periodic pattern sheet (PPS) and glass fiber-reinforced plastic (GFRP) were experimentally investigated. The fabricated RAS effectively absorbed the microwave in the X-band (8.2-12.4 GHz). In order to induce the damage to the RAS, a low-velocity impact test with various impact energy of 15, 40, and 60 J was conducted. Afterward, the impact damage was observed by using visual inspection, non-destructive test, and image processing method. Moreover, the absorbing performance of intact and damaged RAS was measured by the free-space measurement system. The experiment results revealed that the delamination damage from the impact energy of 15 J did not considerably affect the microwave absorbing performance of the RAS. However, fiber breakage and penetration damage with a relatively large damaged area were occuured when the impact energy was increased up to 40 J and 60 J, and these failures significantly degraded the microwave absorbing characteristics of the RAS.

• Proceedings of the Korean Society for Bio-Environment Control Conference
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• 1999.11a
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• pp.13-24
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• 1999

식물이 생장하고 발육하며 자신의 생명을 유지해 나가기 위해서는 끊임없이 에너지를 공급받아야 하는데, 이 에너지의 공급원은 태양으로부터 오는 광에너지이다. 이러한 광에너지는 엽록소(chlorophyll)를 함유한 녹색식물의 잎이나 줄기 등에서 기공(stomata)을 통하여 흡수되는 이산화탄소($CO_2$)와 뿌리에서 주로 흡수되는 물($H_2O$)로부터 당류ㆍ전분과 같은 탄수화물을 합성하고 산소를 방출하는데 이러한 광에너지가 화학에너지로 변환되는 과정을 광합성(photosynthesis) 또는 탄소동화작용(carbon assimilation)이라고 한다. (중략)

• 한국방재학회:학술대회논문집
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• 2009.02b
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• pp.119.2-119.2
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• 2009