• 한국기계가공학회지
• /
• 제8권4호
• /
• pp.90-96
• /
• 2009

The loading condition of actual construction works is complex. The shear effect of mixed-mode load component are crack propagation mechanism in step larger than the crack initial mechanism. Therefore, in this study received a mixed-mode loading on fatigue crack stress ratio on crack propagation path and speed of progress to learn whether stress affects crack propagation. ${\Delta}$ P a constant state of fatigue tests in Mode I, II give the same stress ratio, frequency 10Hz, sinusoidal waveform was used. A lower stress ratio fatigue crack propagation angle is small. This is less affected by the Mode II. Therefore, a mixed-mode fatigue crack propagation is to progress by the Mode. Stress ratio in a mixed mode crack in the path of progress and found a lot of impact.

• 플랜트 저널
• /
• 제7권2호
• /
• pp.44-51
• /
• 2011

Given the fact that the entire bituminous coal used for a boiler is imported, the supply of coal is often affected by the rise of international coal price. Moreover, coal suppliers have been diversified due to the competition among power generation companies for reducing costs and inexpensive sub-bituminous coal is used. As a result, boilers combustion conditions have been deviated from the initial boiler design. This requires the selection of adequate excessive air ratio for different combustion conditions to enhance the efficiency of boiler operation. The boiler efficiency has been identified through an examination on the change of excessive air ratio by mixed fuel in unit 8 of Dangjin power plant complex. In addition, an excessive air ratio was calculated based on the examination result. According to the study result, the adequate excessive air ratio was 13% when Macquarie and Powder river were mixed at a ratio of 5:5 and when Sonoma and Megaprima persada were mixed at a ratio of 5:5. When BHP Billiton and Powder river were mixed at a ratio of 4:6 and Centennial and Batubara were mixed at a ratio of 3:7, the adequate excessive air ratio was 11%.

• 생태와환경
• /
• 제52권2호
• /
• pp.171-177
• /
• 2019

Smart farm is a breakthrough technology that can maximize crop productivity and economy through efficient utilization of space regardless of external environmental factors. This study was conducted to investigate the optimal growth and physiological conditions of Chinese matrimony vine (Lycium chinense) with LED light sources in a smart farm. The light source was composed of red+blue and red+blue+white mixed light using a LED system. In the red+blue mixed light, red and blue colored LEDs were mixed at ratios of 1:1, 2:1, 5:1, and 10:1, with duty ratios varied to 100%, 99%, and 97%. The experimental results showed that the photosynthetic rate according to the types of light sources did not show statistically significant differences. Meanwhile, the photosynthetic rate according to the mixed ratio of the red and the blue light was highest with the red light and blue LED ratio of 1:1 while the water use efficiency was highest with the red and blue LED ratio of 2:1. The photosynthetic rate according to duty ratio was highest with the duty ratio of 99% under the mixed light condition of red+blue+white whereas the water use efficiency was highest with the duty ratio of 97% under the mixed light of red+blue LED. The results indicate that the light source and light quality for the optimal growth of Lycium chinense in the smart farm using the LED system are the mixed light of red+blue (1:1) and the duty ratio of 97%.

• 한국분무공학회지
• /
• 제27권3호
• /
• pp.126-133
• /
• 2022

The objective of this is to experimentally investigate the effect of mixed jet on the oxygen transfer characteristics with the primary nozzle area ratio of an annular nozzle ejector for the application of a microbial fuel cell. A direct visualization method with a high speed camera system was used to capture the horizontal mixed jet images, and a binarization technique was used to analyze the images. The clean water unsteady state technique was used for the oxygen transfer measurement. The air-water mixed jet discharging into a water tank behaved similar to a buoyancy or horizontal jet with the primary nozzle area ratio. It was found that an optimum primary nozzle area ratio was observed where the oxygen transfer performance reached its maximum value due to the decrease of air volume fraction and the increase of jet length and air bubble dispersion.

• 원예과학기술지
• /
• 제31권4호
• /
• pp.415-422
• /
• 2013

본 연구는 식물공장용 LED 챔버 시스템에서 고추냉이의 생육반응에 미치는 LED 광원 및 광질의 영향을 알아보기 위해 적색, 청색, 백색 그리고 원적색광의 단일 및 혼합처리, 적색광과 청색광의 비율 그리고 duty비 등을 다양하게 처리하여 수행하였다. 고추냉이의 생육반응은 적색 + 청색 혼합광에서 가장 높았고, 단일광 조건에서는 청색광보다 적색광 하에서 식물체 생물량이 높았다. 고추냉이의 식물체 생물량과 분얼수는 적색과 청색광의 비율이 1:1인 조건에서 가장 높았다. 적색과 청색광을 혼합하여 처리 시 고추냉이의 생육반응은 duty비가 100%일 때 높은 반면, 적색과 청색광에 백색광을 첨가하여 처리 하였을 때는 duty비가 가장 낮은 97%에서 높았다. 엽면적과 잎건중량은 적색광에서 가장 높은 반면, 비엽면적은 청색광에서 가장 높았다. 적색과 청색 혼합광에서 엽면적과 잎건중량은 적색광의 비율이 높거나, duty비가 낮을수록 증가하였고, 백색광을 첨가한 조건에서는 duty비가 높을수록 증가했다. 이상의 결과를 종합해보면, 고추냉이는 단일광을 처리하는 것보다 적색과 청색광을 혼합하여 처리해 주거나, 청색광보다 적색광의 비율을 더 높여주는 것이 고추냉이의 생육 및 품질을 향상시켜 줄것으로 판단된다.

• 대한기계학회논문집A
• /
• 제31권4호
• /
• pp.432-440
• /
• 2007

In this study, we have investigated the closure behavior of fatigue cracks in SAPH440 steel plates under a mixed-mode I+II loading. A crack image capturing system as a direct measuring method was used to measure the closure levels at a crack tip. The crack closure levels in the fluctuation and stable sections were increased with the increase of the mode mixture ratio. The mode mixture ratio independent fatigue crack propagation rates equation was calculated by considering mixed-mode crack closure levels. The equation was examined according to the application method of crack opening ratio. The fracture surface analysis by C-scan method was also performed in order to investigate the closure mechanism and propagation mode of crack under the mixed-mode I+II loading. The crack closure under the mixed mode I+II is confirmed as a surface roughness closure by the quantitative analysis of fracture surface using the proposed surface roughness parameter.

• 대한전기학회논문지:전기물성ㆍ응용부문C
• /
• 제54권1호
• /
• pp.23-29
• /
• 2005

This paper presents the characteristics of leakage currents flowing through ZinC Oxide(ZnO) surge arrester blocks under mixed direct and 60 Hz alternating voltages. A mixed voltage, in which an alternating voltage is superimposed upon a direct voltage, appears on the HVDC system network. The mixed direct and alternating voltage generator with a peak open-circuit of 10 kV was designed and fabricated. The leakage currents and V-I curves for the fine and used ZnO surge arrester blocks were measured as a function of the voltage ratio k, where the voltage ratio k is defined as the ratio of the peak of alternating voltage to the peak of the mixed voltages. The resistive component in the leakage current in the low conduction region is significantly increased with increasing the voltage ratio k. The V-I characteristic curves for the mixed voltages lies between the direct and alternating characteristics, and the cross-over phenomenon in the high conduction region was appeared.

• Journal of Welding and Joining
• /
• 제26권6호
• /
• pp.42-47
• /
• 2008

TIG welding enables to produce high quality weldment. However it has some problems such as shallow penetration and large distortion due to low penetration aspect ratio after welding. In order to overcome those problems, there are many ongoing studies on A-TIG welding, which use active flux. In this study, the effect of arc length and shield gas on penetration aspect ratio with melt-run welding on STS 304 6t, on which active flux was spreaded, was investigated. Arc length was changed from 1mm to 3mm, and aspect ratio became higher as arc length was decreased in this range. 100% Ar gas, Ar-$H_2$ mixed gas, Ar-He mixed gas, and 100% He gas were used as shield gas in this study. When Ar-$H_2$ mixed gas, Ar-He mixed gas, and 100% He gas were applied, penetration and melting efficiency were both increased as compared with 100% Ar gas. Aspect ratio was the highest with Ar-2.5% $H_2$ mixed gas.

• 한국건축시공학회:학술대회논문집
• /
• 한국건축시공학회 2009년도 추계 학술논문 발표대회
• /
• pp.51-54
• /
• 2009

In this study, the fire resistance test was carried out with a parameter such as fiber(PP+NY) mixed ratio on high strength concrete with 80MPa, and the spalling resistance property was evaluated. Concrete material test was carried out with a parameter such as fiber(PP+NY) mixed ratio(0%, 0.05%, 0.1%, 0.2%) of high strength concrete with 80MPa. Although the flowability and the strength capacity were delicately decreased with a increase of fiber mixed ratio, they satisfied the target limits. As the spalling resistance property after the fire resistance test of 3 hours, the spalling was partly shown on the high strength concrete with fiber(PP+NY) mixed ratio of 0% but, wasn't shown on the high strength concrete with fiber(PP+NY) mixed ratio of 0.05% ~ 0.2%.

• 동력기계공학회지
• /
• 제18권6호
• /
• pp.126-132
• /
• 2014

The P-T characteristics of mixed refrigerant in thermostatic expansion valve sensing bulb were studied using R-134a and R-410A refrigerant. The characteristics of mixed refrigerant were investigated according to pressure variation and the variation of composition ratio of R-134A and R-410A in the temperature range of $-15^{\circ}C{\sim}15^{\circ}C$. The Thermodynamic characteristic values of the mixed refrigerants were identified using the characteristic value analysis program of mixed refrigerant(Refrop v9.0, NIST). The P-T characteristics in the case of the mixing ratio of 90:10 for R-410A and R-134A were the same result as R-22. And the physical properties showed similar results with R-22. The Maximum operating pressure(MOP) of mixed refrigerant showed a tendency to decrease with decreasing the mixing ratio of additive gases($N_2$ or He) gases. The characteristics in the case of the mixing ratio of 80:1 for mixed refrigerant and additive gases were the similar result as Reference refrigerant.(R-22 MOP, Sporlan company) In addition $N_2$ and He, both showed the same results. It was able to confirm that a MOP on the thermostatic expansion valve sensing bulb can be maintained by adjusting the mixing ratio of mixed refrigerant gases and additive gases.