• 전기학회논문지P
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• 제61권3호
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• pp.140-148
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• 2012

Aeronautical lights, which are internationally standardized sequence of colors and placements, are aeronautic safety devices that provide visual information to pilots by continuously adjusting their light intensity to appropriate level. In this paper, we consider the development testing for in pavement LED aeronautical light system such as taxiway centerline, stop line and temporary stop line. The test results of LED sourced lights have shown a drastic improvement in power consumption levels and cost efficiency compared to their halogen sourced counterparts The LED light used only 42.7% as much power as their halogen sourced counterparts. Taking installation costs into account, LED will cost only 58% of its halogen counterparts. These results suggest that developing the LED sourced aeronautical light would result in globally competitive products thar guarantees satisfaction to their consumers, and that both cost effective and energy efficient.

• Smart Structures and Systems
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• 제16권6호
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• pp.1003-1021
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• 2015

MR dampers have been proposed for the control of cable vibration of cable-stayed bridge in recent years due to their high performance and low energy consumption. However, the highly nonlinear feature of MR dampers makes them difficult to be designed with efficient semi-active control algorithms. Simulation study has previously been carried out on the cable-MR damper system using a semi-active control algorithm derived based on the universal design curve of dampers and a bilinear mechanical model of the MR damper. This paper aims to verify the effectiveness of the MR damper for mitigating cable vibration through a full-scale experimental test, using the same semi-active control strategy as in the simulation study. A long stay cable fabricated for a real bridge was set-up with the MR damper installed. The cable was excited under both free and forced vibrations. Different test scenarios were considered where the MR damper was tuned as passive damper with minimum or maximum input current, or the input current of the damper was changed according to the proposed semi-active control algorithm. The effectiveness of the MR damper for controlling the cable vibration was assessed through computing the damping ratio of the cable for free vibration and the root mean square value of acceleration of the cable for forced vibration.

• 자원ㆍ환경경제연구
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• 제29권1호
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• pp.23-45
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• 2020

중국의 급속한 경제성장은 환경에 커다란 부하를 초래하였고, 이를 통해 대기오염 문제도 심각해졌다. 본 연구는 중국의 대기오염 원인을 경험적으로 분석하였다. 표준오차 패널수정 추정기법(PCSE)을 이용하여 중국의 30개 성을 대상으로 아황산가스 및 질소산화물의 배출요인을 분석하였다. 아황산가스의 경우 일인당 실질소득이 증가할수록 배출 수준이 감소하고, 질소산화물은 일인당 실질소득과 역N자형의 관계에 있는 것으로 분석되었다. 소득 이외의 배출 요인으로 우선 전기소비량은 아황산가스나 질소산화물을 증가시키는 요인이었고, 석탄소비량은 아황산가스 배출을 증가시키는 반면에 천연가스 소비량은 아황산가스 배출을 감소시키는 요인으로 나타났다. 한편 에너지 산업에 대한 투자와 폐가스 처리에 대한 투자는 아황산가스 배출을 감소시키는 결정요인이지만 질소산화물 배출에 영향을 미치지 않는 것으로 나타났다. 한편 디젤 소비량, 트럭 비율 및 차량 수는 질소산화물 배출을 증가시키는 것으로 나타났다. 강수량의 증가도 아황산가스와 질소산화물의 배출을 감소시킨 요인이었다. 끝으로 본 연구의 정책적 시사점과 향후 연구방향을 제시하였다.

• Nutrition Research and Practice
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• 제8권4호
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• pp.410-416
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• 2014

BACKGROUND/OBJECTIVES: The standard pattern of Brazilian food consumption is based on the combination of rice and beans served together in the main meals. This study assessed the effects of Brazilian-staple calorie-restricted (BS-diet) dietary advice, with brown rice and beans, on metabolic parameters, body composition, and food intake in overweight/obese subjects. SUBJECTS/METHODS: Twentyseven subjects were randomly assigned to a conventional-type calorie-restricted diet (CT-diet) (n = 13) or a BS-diet (n = 14). Glucose metabolism, lipid profile, anthropometric and body composition parameters, and food intake were measured before and after 16 weeks. Paired t-tests/Wilcoxon tests were used for comparison of differences from baseline and unpaired t-tests/Mann-Whitney tests were used for comparison of differences between the groups. RESULTS: After16 weeks, both groups showed reductions in weight and waist circumference (P < 0.02), and the BS-diet group showed a decrease in body fat (P = 0.0001), and significant improvement in glucose metabolism (fasting plasma glucose, glucose and insulin areas under the curve, Cederholm index, and HOMA2-$%{\beta}$) ($P{\leq}0.04$) and lipid profile (cholesterol, triacylglycerol, LDL-c, VLDL-c, and cholesterol/HDL-c ratio) ($P{\leq}0.05$). In addition, the BS-diet group showed significant improvement in HOMA2-$%{\beta}$, compared to the CT-diet group (P = 0.03). The BS-diet group also showed a significant reduction in energy, lipids, carbohydrate, and cholesterol intake ($P{\leq}0.04$) and an increase in fiber intake ($P{\leq}0.001$), while the CT-diet group showed a significant reduction in intake of energy, macronutrients, PUFA, and cholesterol ($P{\leq}0.002$). CONCLUSIONS: These results demonstrate the benefits of the BS-diet on metabolic parameters in obese subjects.

• 한국물환경학회지
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• 제28권1호
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• pp.129-136
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• 2012

In this century, scientists realized that carbon dioxide gas in the atmosphere cause a greenhouse effect which affects the planet's temperature. Therefore lots of attempts have carried out to decrease the discharge of carbon dioxide gas in the field. The dissolved carbon dioxide flotation (DCF) process was developed as an alternative of DAF process to decrease the discharge and reuse of carbon dioxide as well as to save energy consumption. To investigate the particle separation characteristics and the flotation efficiency of carbon dioxide, SCC model was employed in the DCF process which has been applied extensively for the evaluation and simulation in the DAF process. The simulation results by the SCC model revealed the predicted curve of flotation efficiency became decreased gradually over the optimal pressure range of saturator about 1.6 atm in accordance with the experiment results of the DCF pilot plant and the size distribution and the bubble volume concentration of $CO_{2}$ bubbles depending on the operation pressure of saturator. The findings through the simulation results led to the conclusion that there was no significant difference between $CO_{2}$ bubbles and air bubbles, affecting on the practical flotation efficiency, in terms of the initial collision and attachment efficiency.

• 한국수산과학회지
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• 제25권6호
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• pp.511-519
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• 1992

식품의 가열살균공정에 있어서 자동화는 에너지 소비의 성력화와 품질과의 관계 최적화를 위한 필수조건 중의 하나이다. 이를 위하여 마이크로컴퓨터를 이음한 자동화 시스템을 개발하였다. 시스템의 성능 및 정확도는 고형식품으로 사용한 명태 고기풀의 가열살균과정에서의 열침투곡선과 열확산도의 정확도로써 검토하였다. 자동화 시스템을 이용하여 측정한 명태 고기풀의 열침투곡선은 전형적인 고형식품의 열침투곡선을 나타내었다. 열침투곡선으로 부터 계산된 열확산도의 경우, 일정 살균온도에서는 다른 조건의 변화에 관계없이 일정한 값을 나타내었다. 가열살균온도를 변화시켜 구한 열확산도를 문헌상에 보고된 열확산도 추정식으로 구한 값과 비교하였을 때, 큰 차이를 보이지 않았으며 그 차이는 $\pm10.0\%$이내였다.

• 대한기계학회논문집B
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• 제25권9호
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• pp.1193-1200
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• 2001

There are many regulation test methods to be related with engine emissions such as CVS-75, D-13, ECE-15 modes and so on. Most of these modes are consisted of lots of transient conditions that have rapid acceleration, deceleration and cranking modes. In this experimental research, the engine characteristics of cranking, accelerating and power output in a S.I. engine were studied to compare with neat gasoline and alternative fuels of M30 (methanol 30%, aromatic series 32%, non-aromatic 38%) and M50 (methanol 50%, aromatic 30%, non-aromatic 20%) for performance and exhaust emissions. The results show that reformulated methanol fuels are better emissions reduction of 15.7% over than that of neat gasoline fuel especially in HC and CO emissions at cranking mode. And the accelerating performances coincide with the results of distillation curve. CO concentration for M50 fuel is varied in a just little for the condition of slow acceleration. At wide-open throttle condition, brake specific energy consumption of reformulated fuels is increased and thermal efficiency is some what lower than that of gasoline fuel.

• International Journal of Fluid Machinery and Systems
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• 제10권1호
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• pp.30-39
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• 2017

In the current study, identifying regimes and behaviors of the various viscous fluids in a typical horizontal single-stage centrifugal pump and improving its performance by enhancing volute throat area have been surveyed numerically and experimentally. Indeed the initial pump had insufficient head at BEP (Best Efficient Point) in relevant applications. In order to solve this problem, the method of increasing the volute throat area on the prototype was used in steps and eventually the increased head values have been achieved. Then modified centrifugal pump, that has been constructed based on the modified control volume from numerical results, has been tested thoroughly. The maximum head and efficiency discrepancy between numerical and experimental results in BEP were 1.4 and 2.6% respectively. The effects of viscous fluids, from 1 cSt to 500 cSt, on the performance curves of centrifugal pump have been investigated as well and results showed that viscous fluids has significant effect on them. Indeed the highest head and efficiency in the same conditions at BEP has been obtained in viscosity 1 cst which was by 19.2% and 44% greater than the viscosity 500 cSt. It is also found that the highest viscous fluid had the highest energy consumption as the absorbed power of highest viscous fluid, 500 cSt, increased up to approximately 55% above the lowest viscous fluid, 1 cSt, values.

• 농업과학연구
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• 제47권3호
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• pp.519-532
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• 2020

Because lotus root has a short shelf life, the quality easily deteriorates. Thus, the harvested lotus roots are processed into a variety of products. Drying is one of the simplest food preservation methods, which can increase food stability. However, the convective drying method takes a long time and requires high energy consumption. Combination drying methods have emerged to overcome the limitations of the convective drying method. This study investigated the drying characteristics of lotus root and determined the optimal drying model of lotus root depending on the microwave and hot-air combination drying conditions. The lotus root slices (5 mm in thickness and 40 mm in diameter) were dried by different drying conditions that were combined with three microwave power levels (50, 100, and 150 W) and two hot air temperatures (50 and 60℃) at a velocity of 5 m·s^-1. Eight drying models were tested to evaluate the fit to the experimental drying data, and the effective moisture diffusion (D_eff) values of the lotus root slices dried by combination drying were estimated. The combination drying time of the lotus root was significantly reduced with the high air temperature and microwave power. The effective moisture diffusion (D_eff) of lotus root was more affected by the air temperature than microwave power intensity. Logarithmic model was most suitable to describe the drying curve of lotus root in the microwave-hot air combination drying method.

• 한국안전학회지
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• 제29권4호
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• pp.9-14
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• 2014

Self-piercing riveting(SPR) is a mechanical fastening technique which is put pressure on the rivet for joining the sheets. Unlike a spot welding, SPR joining does not make the harmful gas and $CO_2$ and needs less energy consumption. In this study, static and fatigue tests were conducted using tensile-shear specimens with Al-5052 plates for evaluation of fatigue strength of the SPR joints. During SPR joining process for the specimen, using the current sheet thickness and a rivet, the optimal applied punching force was found to be 21 kN. And, the maximum static strength of the specimen produced at the optimal punching force was 3430 N. During the fatigue tests for the specimens, interface failure mode occurred on the top substrate close to the rivet head in the most high-loading range region, but on the bottom substrate close to the rivet tail in the low -loading range region. There was a relationship between applied load amplitude $P_{amp}$ and lifetime of cycle N for the tensile-shear, $P_{amp}=3395.5{\times}N^{-0.078}$. Using the stress-strain curve of the Al-5052 from tensile test, the simulations for fatigue specimens have been carried out using the implicit finite element code ABAQUS. The relation between von-Mises equivalent stress amplitude and number of cycles was found to be ${\sigma}_{eq}=514.7{\times}N^{-0.033}$.