• Journal of Welding and Joining
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• 제15권4호
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• pp.178-186
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• 1997

The purpose of this study is to evaluate the J-R curve characteristics for the 5083 aluminum alloy weldment by the load ratio analysis. The results of the load ratio analysis are compared with those of the J-R curve which are obtained by the ASTM unloading compliance method. The crack length calculated by the load ratio analysis is agrees well with the measured final crack length. The slope of the exponential J-R curve estimated by the load ratio analysis is slightly smaller than that by the ASTM unloading compliance method. The exponential correlation of the J-R curve for the 5083 aluminum alloy base metal by the load ratio analysis is J = 93.88 ${\Delta}{\alpha}^{0.375}$. That for the weld metal and HAZ is J = 69.87 ${\Delta}{\alpha}^{0.389}$ and J = 70.59 ${\Delta}{\alpha}^{0.359}$ respectively. The J-R curve obtained by the ASTM unloading compliance method is overpredicted and should be offsetted due to the initial negative crack. On the other hand, the load ratio analysis method can evaluate the J-R curve by only load displacement curve without particular crack measurement equipment.

• 동력기계공학회지
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• 제1권1호
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• pp.80-90
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• 1997

The purpose of this study is to evaluate the validity examination of the J-R curve characteristics for the nuclear reactor pressure vessel steels and Al alloys by the load ratio analysis. The results of the load ratio analysis are compared with those of the J-R curve which are obtained by the ASTM unloading compliance method. The crack length calculated by the load ratio analysis is agree well with the measured final crack length. The slope of the exponential J-R curve estimated by the load ratio analysis is slightly smaller than that by the ASTM unloading compliance method. The J-R curve obtained by the ASTM unloading compliance method is over-predicted and should be offsetted due to the initial negative crack. On the other hand, the load ratio analysis method can evaluate the J-R curve by only load-displacement curve without particular crack measurement equipment.

• 한국압력기기공학회 논문집
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• 제12권2호
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• pp.34-39
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• 2016

This paper presents a method to quantify R-ratio effect on J-integral under large-amplitude cyclic loading condition. Generally, monotonic tearing resistance curves are used to assess stability of cracked nuclear piping under seismic loading. However, it is well known that fracture toughness decrease at cyclic loading condition, according to R-ratio. For this reason, it is important to quantify the J-R curves under cyclic loading condition. To quantify the R-ratio effect, correction method which was proposed by Tranchand is considered. This method considers crack opening area in order to calculate modified J-integral. This method leads to an increase of fracture toughness. At R=-0.5 case, this method is good agreement with monotonic J-R curves. However, results show that this method has a limit to apply a large R-ratio case.

• 대한임상검사과학회지
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• 제55권1호
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• pp.9-15
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• 2023

본 연구의 목적은 당뇨 검사결과와 간기능검사와의 관계연구이다. 간성당뇨는 제2형 당뇨와는 다르게 간기능 이상으로 기인하는 것이다. 본 연구에서 간기능 검사의 주요 효소검사인 아스파르트산 아미노전이효소(aspartate aminotransferase, AST), 알라닌 아미노전이효소(alanine aminotransferase, ALT) 그리고 AST/ALT ratio (De Ritis ratio)와 당뇨관련 검사와의 관계를 주로 확인하였다. 연구 결과 AST와 글루코스(glucose) (r=0.14, P<0.01); ALT 및 글루코스(r=0.21, P<0.01); AST 및 당화혈색소(HbAlc) (r=0.15, P<0.01); ALT와 HbAlc (r=0.20, P<0.01), 모든 변수는 양의 상관관계를 나타났으며, De Ritis ratio는 글루코스 (r=-0.20, P<0.01)와 당화혈색소 (r=-0.14, P<0.01)와 음의 상관관계를 보였다. AST와 ALT 그리고 De Ritis ratio 를 독립변수로 하고 글루코스 (R²=0.05) 와 HbA1c (R²=0.04) 를 종속변수로 하여 회귀분석한 결과 독립변수는 종속변수에 통계적으로 유의하게 영향을 나타내는 것으로 나타났다. AST는 ALT 보다 혈당과 당화혈색소에서 상관관계가 낮게 나타났으며, ALT가 증가하는 것은 즉, De Ritis ratio 감소의 원인이 된다. 따라서, De Ritis ratio는 당뇨관련 검사와의 관계에서 의미가 있는 것으로 볼 수 있다.

• 설비공학논문집
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• 제4권2호
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• pp.123-136
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• 1992

A preliminary thermodynamic design model of two-evaporator refrigerator/freezer system is constructed. This system is based on Lorentz-Meutzner cycle using refrigerant mixtures. This model screens alternative refrigerant (R32, R125, R143a, R22, R134a, R152a, R124, R142b, R123) mixtures to select the best performance-giving refrigerant mixtures and its composition for the system. Also, it estimates the effects of cooling temperatures of intercoolers, evaporator's area ratio, cooling load ratio on the performance of the system. The COP of the system ranges from 1.4 to 1.6, which is superior to that of the single evaporator system charged with R12 by 13% to 29%. Among 15 mixtures, R22/R123, R143a/R123, R32/R142b, and R32/R124 (in the order of high COP) are most recommendable. For the case of R22/R123, R22 mass fraction more than 0.5(Load Ratio=1.0) or 0.7(Load Ratio=0.33) is recomended in order to replace R12 without reduction in volumetric capacity when keeping the compressor as the same one. COP has the highest value with X(R22)=0.7 and 0.8, respectively. For the case of R143a/R123, in the similar manner, mass fraction of R143a is more than 0.5 or 0.6 while best performance occurs at X(R143a)=0.8. Higher temperature intercooler is more important for the performance of the system than lower temperature intercooler. The area ratio of evaporators is roughly proportional to load ratio of the evaporators.

• 대한의용생체공학회:의공학회지
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• 제22권2호
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• pp.197-204
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• 2001

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 1997년도 특별강연 및 춘계학술발표 개요집
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• pp.91-98
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• 1997

This research is to evaluate of the J-R curve characteristic in 5083 aluminum alloy weldment by utilizing the load ratio analysis. This analysis method can be evaluated the J-R curve only with load-displacement curve without any particular precision instrument equipment in CT specimen. For validity, the results of the load ratio analysis are compared with the those of the J-R curve, which are obtained by the ASTM standard unloading compliance method. The calculated crack length of the load ratio analysis is well appropriate that the measured final crack length. And the J-R curve slope estimated by the load ratio analysis is slightly smaller than that by the ASTM unloading compliance method.

• International Journal of Automotive Technology
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• 제7권3호
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• pp.277-282
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• 2006

With the aim of achieving half the regulated value of EURO-3 Emission Regulations, an ultra low emission motorcycle has been developed based on a motorcycle with an 1800 $cm^3$, horizontal opposed 6-cylinder engine. For the fuel supply system, an electronically controlled fuel injection system was applied. For the emission purification system, three-way catalysts, a feedback control system with a LAF(Linear Air-Fuel ratio) sensor, and a secondary air induction system were applied. To reduce CO and HC emissions during cold starting, an early catalyst activation method combining RACV(Rotary Air Control Valve) and retarded ignition timing was applied. After the catalyst activation, air-fuel ratio was controlled to maximize the purification ratio of the catalyst according to vehicle speed. For the air-fuel ratio control system, the LAF sensor was used. Furthermore, fine adjustment by the LAF feedback control reduced torque fluctuation due to the air-fuel ratio change. As a result, smooth ride feeling was maintained. Owing to these technologies, half the regulated value of EURO-3 has been achieved without any negative impact to the large-scaled motorcycles' drivability. This paper presents the developed ultra low emission technologies including the control method using an LAF sensor.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1995년도 봄 학술발표회 논문집
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• pp.130-135
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• 1995

We can consider that the study on early evaluation of strength of concrete is useful to raise safety of building and utility of quality control of concrete is useful to raise safety of building and utility of quality control of concrete. In this paper, was proposed to method early to predict strength of concrete with key parameters, such as Water/Cement(W/C) ratio and Sand / Aggregate(S/A) ratio. Through a series of experiment, the obtained results are summarized as follow. $\circled1$ The ratio of resistance was decteased as the increase of W/C ratio. $\circled2$ The maximum value for the ratio of resistance and compressive strength was presented in the case of 40% S/A ratio. $\circled3$ The relationship. of the ratio of resistance and compressive strength on 28days according to the change of W/C and S/A ratio is to be: $F_{28}=-0.00104R^2 + 2.263R - 935.5$ (W/C Ratio) $F_{28} = 0.007R^2 - 10.693R - 4269.1$ (S/A Ratio)

• 한국물환경학회지
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• 제21권6호
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• pp.687-694
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• 2005

Lab-scale experiments have been carried out to investigate the effect of F/R ratio of ASBR (Anaerobic Sequencing Batch Reactor) process on the removal of the organic matters in ammonia stripped swine wastewater. Three ASBR inoculated with sludge mixed with granular sludge of UASB (Upflow Anaerobic Sludge Blanket) and anaerobic digested sludge of municipal wastewater treatment plant were operated. Ammonia stripped swine wastewater was used as influent. Prior to conducting the experiments with varied conditions, the effect of increasing organic loading rate from 2.34 to $5.79gTCOD_{Cr}/L$-day at a fixed F/R ratio of 0.1 on the organic removal efficiency has been studied during start-up period. As the result of the experiment, under the condition of varied organic loadings, less than $4.14gTCOD_{Cr}/L$-day, the removed efficiency $TCOD_{Cr}$ of the ASBR process is 83% resulted from the mean value of effluent $TCOD_{Cr}$, 9,125 mg/L during the start-up period. Then ASBRs were operated with F/R ratio of 0.024, 0.303 and 0.91 respectively. Organic loading rate was increased from 4.56 to $15.43gTCOD_{Cr}/L$-day to investigate the effects of F/R ratio and organic loading rate on the organic removal efficiency. As the result of the experiment, less than $6.23gTCOD_{Cr}/L$/L-day, F/R ratio haven't an effect on the organic removal efficiency and the mean removal efficiency of TSS, $TCOD_{Cr}$ and $SCOD_{Cr}$ was about 80%, 86% and 78% at the all of F/R ratio. But as organic loading rate was increased from 8.54 to $12.04gTCOD_{Cr}/L$-day at the F/R ratio of 0.024, the removal efficiency of $SCOD_{Cr}$ decreased from 71% to 63%. The range of decreased removal efficiency of $SCOD_{Cr}$ at the F/R ratio of 0.024 was much more higher than at the F/R ratio of 0.303, 0.91. Thus, as organic loading rate was increased, ASBRs were operated with high F/R ratio to obtain high removal efficiency.