• Structural Engineering and Mechanics
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• 제35권5호
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• pp.571-592
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• 2010

An energy-based fatigue life prediction framework was previously developed by the authors for prediction of axial, bending and shear fatigue life at various stress ratios. The framework for the prediction of fatigue life via energy analysis was based on a new constitutive law, which states the following: the amount of energy required to fracture a material is constant. In the first part of this study, energy expressions that construct the constitutive law are equated in the form of total strain energy and the distortion energy dissipated in a fatigue cycle. The resulting equation is further evaluated to acquire the equivalent stress per cycle using energy based methodologies. The equivalent stress expressions are developed both for biaxial and multiaxial fatigue loads and are used to predict the number of cycles to failure based on previously developed prediction criterion. The equivalent stress expressions developed in this study are further used in a new finite element procedure to predict the fatigue life for two and three dimensional structures. In the second part of this study, a new Quadrilateral fatigue finite element is developed through integration of constitutive law into minimum potential energy formulation. This new QUAD-4 element is capable of simulating biaxial fatigue problems. The final output of this finite element analysis both using equivalent stress approach and using the new QUAD-4 fatigue element, is in the form of number of cycles to failure for each element on a scale in ascending or descending order. Therefore, the new finite element framework can provide the number of cycles to failure at each location in gas turbine engine structural components. In order to obtain experimental data for comparison, an Al6061-T6 plate is tested using a previously developed vibration based testing framework. The finite element analysis is performed for Al6061-T6 aluminum and the results are compared with experimental results.

• 에너지공학
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• 제22권3호
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• pp.262-269
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• 2013

가정부문 에너지소비는 국가마다 중요한 에너지절약 목표로 간주되고 있다. 이는 에너지절약 측면뿐 만 아니라 소비자의 경제적 지출 측면에서도 매우 중요한 문제이다. 특히 가정부문 에너지소비는 소비자의 라이프스타일과 매우 밀접한 관계가 있다. 그럼에도 불구하고 이에 대한 심도 있는 연구는 거의 없었다. 이에 따라 본고는 구조방정식 모형을 통해 에너지절약행동에 있어서 소비자의 라이프스타일 유형이 어떠한 영향을 미치는지를 살펴보았다. 연구결과, 생활만족형 절약의식형 및 절약실천형 라이프스타일은 환경보전의식 및 환경보전의식과 정(+)의 관계가 있으며, 경제적 비용인식과 환경보전의식은 에너지절약의식과 정(+)의 관계로 확인되었다. 그리고 에너지절약의식과 에너지절약행동은 정(+)의 관계가 있는 것으로 분석되었다.

• 한국태양에너지학회 논문집
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• 제35권3호
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• pp.81-91
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• 2015

LED has received intensive research attention due to its long life, high efficacy, fast response and wide colour availability, and has secured extensive application areas. However, LED chips within the modules convert only fraction of electric energy into light, and majority of supplied energy needs to be dissipated as heat, which challenges in the performance and life of the LED modules. IEC 62717 specifies the performance requirements for LED modules together with the test methods and conditions. The present study examined the influence of different design parameters on performance temperature through series of experiments and numerical simulations. The economic means to change the module performance temperature during the measurement of mandatory markings were suggested based on predicted cooling performances.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1991년도 추계학술대회 논문집 학회본부
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• pp.63-66
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• 1991

With the diversity of life patterns and the improvement of level in life which have been resulted from the economic development, people have showed the tendency to pursue the comfortable life as well as the home automation or intelligent house. Furthermore, the clean energy supply and management system have been introduced for the solution of environmental problem on earth and the effective utilization of energy. This study is to describe the battery energy storage device, which is one of the clean energy supply and management systems that are economically efficient in both sides of supply and demand. and able to solve the problem of energy crisis.

• 한국신뢰성학회지:신뢰성응용연구
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• 제13권1호
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• pp.55-63
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• 2013

For a reliability assessment of large machinery parts, reliable data should be obtained from testing many samples for a long time. However, in case of testing these samples, testing cost is excessive; in case of life test for long time, power consumption is high; and in case of accelerated test by over load, very high cost is required to build the life testing device. Especially it is very frequent that the expensive device's life has ended during a accelerated test by over load. In this study, the design mechanism of the life testing device which excels in energy saving during the reliability test of large machinery parts has been introduced.

• 한국신뢰성학회지:신뢰성응용연구
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• 제12권2호
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• pp.67-78
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• 2012

An electric double-layer capacitor(EDLC) is an electrochemical capacitor with relatively high energy density, typically hundreds of times greater than conventional electrolytic capacitors. EDLCs are widely used for energy storage rather than as general-purpose circuit components. They have a variety of commercial applications, notably in energy smoothing and momentary-load devices, and energy-storage and kinetic energy recovery system devices used in vehicles, etc. This paper presents an accelerated degradation test of an EDLC with rated voltage 2.7V, capacitance 100F, and usage temperature $-40^{\circ}C{\sim}65^{\circ}C$. The EDLCs are tested at $50^{\circ}C$, $60^{\circ}C$, and $70^{\circ}C$, respectively for 1,750hours, and their capacitances are measured at predetermined times by constant current discharge method. The failure times are predicted from their capacitance deterioration patterns, where the failure is defined as 30% capacitance decrease from the initial one. It is assumed that the lifetime distribution of EDLC follows Weibull and Arrhenius life-stress relationship holds. The life-stress relationship, acceleration factor, and $B_{10}$ life at design condition are estimated by analyzing the accelerated life test data.

• Journal of Photoscience
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• 제9권2호
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• pp.170-173
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• 2002

Space is full of energetic events emitting high-energy radiations which may be fatal to all living things unless protected. The present paper briefly describes high-energy photons and particles incident on Earth surface and their common properties toward living things. Role of radiation played in evolution of life and earth environment will be presented.

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 2005년도 춘계학술발표회
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• pp.1002-1003
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• 2005

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 2002년도 춘계공동학술발표회요약집
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• pp.303-303
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• 2002

• Asian-Australasian Journal of Animal Sciences
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• 제7권1호
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• pp.103-112
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• 1994

This study was a sequential experiment consisting if feeding trial and in vitro culture studies. Feeding was conducted by $2{\times}2{\times}2$ factorial design with two cimaterol levels (0, 0.25 mg/kg), two energy levels (3,200, 2,900 ME kcal/kg) and two sexes. In starting period (0-21 days) broilers were fed diets containing two energy level without dietary supplementation of cimaterol. During finishing period (21-42 days) cimaterol groups were fed cimaterol supplemented diets. In vitro cultures were carried out to study the cellular metabolism of protein and fat in liver and adipose tissues prepared from chicks used in feeding trials. Body weight gain was significantly improved by the administration of cimaterol to experimental diets by 2.4% (p < 0.05). Feed intake was reduced by cimaterol administration at the high energy level, but this trend was reversed at low energy level. Feed efficiency was improved by cimaterol administration and at high energy level the difference (5.7%) was significant(p < 0.05). The administration of cimaterol had no effects on percentage of abdominal fat content, giblet and neck. There was little difference in carcass yield between control and cimaterol treated group. The administration of cimaterol had no effects on nutrient metabolizability or carcass composition. The results of in vitro studies with liver tissues showed that cimaterol increased the lipolytic activities (p < 0.05) and decreased lipogenic activities (p < 0.05). In in vitro studies with acinar cell of liver tissues. cimaterol increased the amount of retained protein and decreased secreted protein at high energy level. but the trend was opposite at low energy level.