• 설비공학논문집
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• 제10권6호
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• pp.658-665
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• 1998

This paper investigates local exhaust effectiveness in a room with a supply and an exhaust slots on the ceiling. The mean age of air is an indicator of supply effectiveness, while the mean residual life time can be used as an indicator of exhaust effectiveness. The distribution of local mean residual life time in a space is calculated by four different numerical procedures. The reverse-flow calculation method has been proved to show quite accurate results while it can save considerable amount of computation time and efforts, compared to the method by its original definition. It is concluded that the diffusion term in the equation of mean residual life time can be neglected. The spatial and temporal diffusion characteristics of the contaminant are also discussed.

• International Journal of Reliability and Applications
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• 제3권2호
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• pp.91-98
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• 2002

A class of life distributions, whose mean residual life keeps stable at its earlier phase and then starts to decrease in time, is proposed to model the life of an element haying survived its burn-in. A strongly consistent estimator and a nonparametric testing procedure are developed to locate the occurrence of the change-point of the mean residual life. Finally, some numerical simulations are employed to be an illustration as well.

• 농약과학회지
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• 제12권4호
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• pp.397-402
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• 2008

Emamectin benzoate와 pyridaben에 대한 담배가루이의 잔효성과 섭식행동의 상관관계를 조사하였다. EPG의 파형은 non-probe time과 phloem phase time과 같은 파형을 신호개시 후 3시간 동안 기록하여 분석하였다. EPG 파형 중 non-probe time과 phloem phase time의 두 파형과 emamectin benzoate와 Pyridaben의 두 약제 간 잔효성의 상관관계 분석에서 모두 상관관계가 있는 것으로 나타났다. 잔효성은 두 약제 모두 2일까지는 50%로 비슷하였으나, 그 이후로는 pyridaben보다 emamectin benzoate가 급격히 감소하였다. EPG를 이용한 두 약제의 잔효성에 따른 구침을 찌른 시간과 체관부 섭식행동은 9일 이후부터 증가하는 경향을 보였으며, emamectin benzoate가 pyridaben보다 증가하는 속도가 빨랐다.

• 한국물환경학회지
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• 제20권3호
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• pp.206-214
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• 2004

Residual wall thicknesses, corrosion rates, and residual life of thirty four samples of cast iron pipes(CIPs) and ductile cast iron pipes(DCIPs) collected from water mains of B city were studied to estimate their remaining service life or optimum time of rehabilitation. The internal maximum corrosion depths of samples measured using a dial gauge after shot blasting were twice higher than the external in most cases. Therefore corrosion of water pipes was much more affected by internal water quality than soil. Residual wall thicknesses of DCIPs were higher than those of CIPs. That reason was thought to be that DCIPs have been protected from internal corrosion by lining cement mortar. Residual life calculated by maximum corrosion rate was ranged up to 44 years with 12.40 years average. Since most CIPs were much deteriorated, rehabilitation plan should be established soon in B city. Residual life of DCIP was 33.52 years average. When cement mortar lining is used up by neutralization of DCIPs. DCIP also should be rehabilitated.

• 상하수도학회지
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• 제23권3호
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• pp.305-313
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• 2009

This paper provides a method for evaluating a residual life of water mains using a proportional hazard model(PHM). The survival time of individual pipe is defined as the elapsed time since installation until a break rate of individual pipe exceeds the Threshold Break Rate. A break rate of an individual pipe is estimated by using the General Pipe Break Model(GPBM). In order to use the GPBM effectively, improvement of the GPBM is presented in this paper by utilizing additional break data that is the cumulative number of pipe break of 0 for the time of installation and adjusting a value of weighting factor(WF). The residual lives and hazard ratios of the case study pipes of which the cumulative number of pipe breaks is more than one is estimated by using the estimated survival function. It is found that the average residual lives of the steel and cast iron pipes are about 25.1 and 21 years, respectively. The hazard rate of the cast iron pipes is found to be higher than the steel pipes until 20 years since installation. However, the hazard rate of the cast iron pipes become lower than the hazard rates of the steel pipes after 20 years since installation.

• 여성건강간호학회지
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• 제17권3호
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• pp.294-303
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• 2011

Purpose: This study aimed to describe bladder dysfunction in elderly women such as frequency, nocturia, and residual urine. Methods: One hundred elderly women aged 60 and over. The Bristol Female Lower Urinary Symptoms (BFLUT) was used to evaluate the bladder function and to measure the residual urine amount by using a bladder scanner. Data was analyzed with the differences between voiding dysfunction by age group and life habits by t-test, ANOVA and correlation by Pearson correlation coefficient. Results: the mean daytime frequency was 6.8 times and night-time frequency 2.7 times. Sixty three percent of subjects had urgency and 41% had urgent incontinence. Over half of subjects had problem in voiding function. There were significant differences in frequency by age groups and constipation, but not in daytime frequency and residual urine. Lastly, there were significant positive relations between daytime frequency and night-time frequency. Also results indicate that more frequency in daytime equaled to a less residual urine amount. Conclusion: We know many elderly women have lower urinary tract symptoms. Specially women over 75 years have more daytime frequency and night-time frequency. This suggests further research needed in order to understand the relation of voiding patterns and life habits and its influence on quality of life.

• International Journal of Air-Conditioning and Refrigeration
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• 제10권4호
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• pp.177-183
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• 2002

A pulsed tracer gas technique is applied to measure the distributions of local mean age and local mean residual-life-time of air in a half-scale experimental chamber, The airflow patterns in the chamber are visualized by a Helium bubble generator for three different exhaust locations. A supply slot is located at the top of a right wall, and an exhaust slot is at either bottom-left (Case 1), bottom-right (Case 2), or top-left (Case 3) location. Results show that the distributions of local mean age and local mean residual-life-time are different from each other, but both of them are closely related to the airflow pattern in the space. Included are discussions on explaining the variations of overall room ventilation effectiveness depending upon airflow rates for three different supply-exhaust configurations.

• International Journal of Reliability and Applications
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• 제6권2호
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• pp.79-85
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• 2005

We show how comparative mean residual life functions (MRL) can be used to give unique insights into strengths of materials data. Recall that Weibull's original reliability function was developed studying and fitting strengths for various materials. This creative comparing of MRL functions approach can be used for regular life data or any time to response data. We apply graphical MRL's to real data from tests of tensile strength of high quality engineered wood.

• 대한기계학회논문집A
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• 제30권9호
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• pp.1110-1115
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• 2006

Cold expansion of fastener holes has been successfully used for many years to impart beneficial compressive residual stresses. Beneficial compressive residual stress of fastener hole that has been cold expanded before is reduced by using of materials for a long time. As a result, fatigue life of material is reduced. So, compressive residual stresses of material have to regenerate by re-cold expansion method. In this paper, it was carried out a finite element analysis about variation of residual stress due to tensile stress and residual stress distribution that was regenerated by re-cold expansion method in the fastener hole. Here, a diversity tensile stress was used. Also, it was performed a finite element analysis according to cold expansion rate of re cold expansion in order to obtain a beneficial compressive residual stress.

• 한국수자원학회논문집
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• 제50권10호
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• pp.673-679
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• 2017

본 논문에서는 상수관로의 효율적인 유지 관리를 위해 상수도 기술진단에서 점수평가법으로 도출된 관망성능평가결과를 이용한 상수도 관로의 내구연수 및 잔존수명 산정 방법을 제시하였다. 본 연구에서 잔존수명은 '모델에 의해 추정된 매설 후 최적교체시기까지 경과년수'를 의미하는 '내구연수'와 매설 후 경과년수의 차이로 정의하였으며, 내구연수는 관망성능평가기준으로 제시된 노후관로 판정기준 점수에 도달하는 시점으로 정의하였다. 연구대상지역의 관망성능평가에 사용된 평가항목들과 노후도 점수를 상수도 관로의 잔존수명 추정을 위한 다중회귀모델의 변수로 사용하였다. 잔존수명의 산정에 필요한 내구연수를 추정하기 위하여 구축된 회귀모델에 독립변수로 사용된 노후도 점수를 나타내는 변수의 값으로 노후관로 판정기준 점수에 해당하는 값을 대입하였다. 개발된 회귀모델을 이용하여 연구대상지역 상수도 관로의 내구연수 및 잔존수명을 산정하였으며 그 결과를 지방공기업법에서 제시하고 있는 내용연수와 비교하여 분석하였다.