• Proceedings of the Korea Concrete Institute Conference
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• 2005.05b
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• pp.33-36
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• 2005

Recently, the use of volcanic-ash as a part of cement content in concrete is very common. But, it has been indicated that the compressive strength of concrete using large amount of volcanic-ash as a part of cement content in early age is low and carbonation velocity is fast. To solve those problems, High Volume Volcanic-Ash Concrete which contained large amount of volcanic-ash as a part of fine aggregate has been proposed. This is an experimential study to compare and analyze the properties of High Volumn Volcanic-Ash Concrete according to the replacement method and ratio of volcanic-ash. For this purpose, the mix proportion of concrete according to the replacement method(PL, C10, C150, A10, A100, A150) And then slump, setting time, bleeding, compressive strength, tensile strength and carbornation test were performed. According to test results, it was found that the compressive strength of the concrete using the volcanic-ash as a part of fine aggregate(A) was higher than that of the concrete using the volcanic-ash as a part of cement content(C). And, the compressive strength of the A concrete increased in early age as well as in long tern age as the volcanic-ash content increased.

• Asian-Australasian Journal of Animal Sciences
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• v.24 no.1
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• pp.45-55
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• 2011

A feeding trial was conducted to study the replacement value of concentrates with Barhar (Artocarpus lakocha) leaves on growth performance of kids fed a mixed jungle grass-based diet. Fifteen Sikkim local kids, about 4 months of age and body weight ranging from 5.8 to 9.2 kg, were randomly distributed into three groups of five. Kids were stall fed ad lib with mixed jungle grass collected from the nearby forest and native scrubland. The kids in group I received supplementary concentrate (Maize 35%, mustard cake 32%, rice bran 30%, mineral mixture 2% and common salt 1%) at approximately 2% of BW. For groups II and III, 25 and 50% of the concentrate was replaced with Barhar (Artocarpus lakocha) leaves, respectively. Total dry matter intake (DMI) was not significantly different among groups. Digestibility of CP decreased (p<0.05) and that of NDF increased (p<0.01) with increasing level of Barhar leaves in the diet. Digestibility of ADF (p<0.01), hemi cellulose (p<0.05) and cellulose (p<0.01) was higher in groups II and III than in group I. Ruminal pH and TVFA concentration were not significantly different among groups. Rumen ammonia-N concentration decreased (p<0.01) with increased level of Barhar leaves in the diet. Similarly, plasma urea nitrogen and blood glucose levels were reduced (p<0.05) with increasing level of Barhar leaves in the diet. Replacement of concentrate with Barhar resulted in reduced Hb and lower serum iron concentration. Levels of other serum metabolites including minerals were not altered by the replacement. Average daily gain (ADG) was 53.3, 54.4 and 41.8 g/d in groups I, II and III, respectively. ADG was not adversely affected when the level of replacement was restricted to 25%. However, at 50% of replacement ADG was significantly lower than the control (p<0.05). Thus, it was concluded that Barhar leaves might replace 25% of the supplemental concentrate for growing Sikkim local kids fed on a mixed jungle grass-based diet.

• Journal of Korean Foot and Ankle Society
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• v.10 no.1
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• pp.92-95
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• 2006

Purpose: Ankle fusion that is operated on severe ankle arthritis has its weakness in that normal walking is impossible, even though the result is pretty good. As a alternative choice, total ankle replacement pursues the longer survivorship with material improvement. However, it is not yet known how much range of motion is possible after the replacement, or how it has changed overtime. Therefore, we need an analyzation for that. Materials and Methods: A retrospective review of sixty-seven patients undergoing STAR total ankle replacement at our institution between 1998 and 2002 was conducted. Of those, twenty-six (39%) had complete sets of full dorsiflexion and plantar flexion lateral radiographs both between "immediate" postop and at a minimum of 2-years follow-up and no revision procedure during that time. The mean age of these patients was 63.2 years when the surgery was done; the etiology of arthrosis was 21(81%) post-traumatic/degenerative, 4 rheumatoid and 1 psoriatic. Results: Average "immediate" ankle range of motion was $15.9^{\circ}$, and total foot (non-ankle) motion was $20.6^{\circ}$. At one, two, and three years the average ankle and total foot ranges of motion were $17.4^{\circ}$, $17.6^{\circ}$, $15.6^{\circ}$ and $21.0^{\circ}$, $22.0^{\circ}$, $21.2^{\circ}$ respectively. Statistically there was no significant difference between "immediate" postop motion and one to three years postop (all p>0.05). Conclusion: The range of motion after the STAR total ankle replacement is maintained from the "immediate" postoperative range of motion, but not increased, in the 1-3 year post replacement period.

• The Journal of the Convergence on Culture Technology
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• v.4 no.4
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• pp.201-206
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• 2018

The fourth fiscal estimate of the national pension following the aging of the population and falling yields estimated that the fund ran out in 2057, three years earlier than the third fiscal calculation. Accordingly, the government proposed a plan to immediately raise the insurance premium rate by 2 percent and maintain the income replacement rate by 45 percent, and to reduce the income replacement rate by 40 percent in 2028. In this form, increasing premiums and reducing income replacement rates will allow younger generations to sign up differently from existing subscribers, who previously had higher income replacement rates at lower rates. Therefore, the study aims to ease the burden on the elderly and younger by applying different insurance rates and income replacement rates for different ages.

• Computers and Concrete
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• v.34 no.1
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• pp.33-48
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• 2024

This paper presents the detailed experimental and analytical investigation on the evolution of static (E_s) and dynamic modulus of elasticity (E_d) of concrete having 0%, 35%, and 50% FA used as partial cement replacement. Destructive and non-destructive tests were conducted on cylindrical specimens to evaluate the compressive strength and MoE of concrete in compression at the age of 28, 56, 90, and 150 days for all mixes. Experimental results show that the concrete having 35% FA achieved compressive strength and MoE similar to plain concrete at the age of 90 days, while 50% FA concrete attained satisfactory compressive strength and MoE at the age of 150 days. The comprehensive statistical analysis has been carried out in two ways on the basis of the experimental results. Firstly, the 28-day crushing strength of plain concrete in compression was used to design the models for the prediction of E_s and E_d of fly ash concrete at any age and percentage replacement of FA. Secondly, using the values of UPV and RHN, models have been developed to predict the age or time-dependent E_s and E_d of fly ash concrete. These models will be helpful in assessing the E_s and E_d of fly ash concrete without knowing the 28-day crushing strength of plain concrete in compression in the laboratory. Hence, the suggested models in the present study will be beneficial in conducting the health assessment of fly ash based concrete structures.

• Journal of the Korean Data and Information Science Society
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• v.14 no.2
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• pp.393-403
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• 2003

In this paper, various replacement policies for the general failure model are considered. There are two types of failure in the general failure model. One is Type I failure (minor failure) which can be removed by a minimal repair and the other is Type II failure (catastrophic failure) which can be removed only by a complete repair. In this model, when the unit fails at its age t, Type I failure occurs with probability 1-p(t) and Type II failure occurs with probability p(t), $0{\leq}p(t){\leq}1$. Under the model, optimal replacement policies for the long-run average cost rate and the limiting efficiency are considered. Also taking the cost and the efficiency into consideration at the same time, the properties of the optimal policies under the Cost-Priority-Criterion and the Efficiency-Priority-Criterion are obtained.

• Proceedings of the Korea Concrete Institute Conference
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• 1998.10c
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• pp.139-144
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• 1998

This study is intended to devolop the self waterproof agents for high performance concrete by analyzing the properties of fresh and hardened mortar with various addition ratios of the inorganic admixture and zinc stearate. As the results of the test, the flow and air content increase with the addition of expansive additives. When the replacement rate of silica fume increases, the flow decreases for the increased viscidity. And the flow and sir content decrease with the addition of zinc stearate. At hardened state, the compressive strength, tensile strength and flexual strength decrease with the addition of expansive additives and zinc stearate. With the increase of silica fume's replacement, they show a little decrease at early age and then increase gradually. Also, absorption and permeability show a steep decrease when zinc stearate is added, and a slack decrease with the replacement of silica fume.

• Journal of Korean Society for Quality Management
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• v.31 no.3
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• pp.185-192
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• 2003

In this paper, the properties on the optimal replacement policies for the general failure model are developed. In the general failure model, two types of system failures may occur : one is Type I failure (minor failure) which can be removed by a minimal repair and the other, Type II failure (catastrophic failure) which can be removed only by complete repair. It is assumed that, when the unit fails, Type I failure occurs with probability 1-p and Type II failure occurs with probability p, $0\leqp\leq1$. Under the model, the system is minimally repaired for each Type I failure, and it is repaired completely at the time of the Type II failure or at its age T, whichever occurs first. We further assume that the repair times are non-negligible. It is assumed that the minimal repair times in a renewal cycle consist of a strictly increasing geometric process. Under this model, we study the properties on the optimal replacement policy minimizing the long-run average cost per unit time.

• Journal of Chest Surgery
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• v.25 no.9
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• pp.976-981
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• 1992

The results of the clinical observations on the 158 cases of the mitral valvular heart disease treated at the Department of Thoracic and Cardiovascular Surgery, Masan Koryo General Hospital from June, 1986 to December, 1991 were as follows; 1. There were 50 men and 108 women with sex ratio 1: 2.2. 2. The age of patient varied widely from 13 years to 65years. 3. The preoperative functional level accoridng to the NYHA classification were class II, III, IV in 18%, 67%, 15%. 4. All 158 patients were operated on under direct vision using extracorporeal circulation, mitral valve replacement in 118 cases, mitral and aortic valve replacement 40 cases. 5. The follow up period was between 2 months and 65 months postoperatively. [mean 30.1 months] 6. The early operative motality was 5.7%[9 cases], late motality was 4%[6 cases]. 7. The cardiothoracic ratio in the chest X-ray decreased at the 6th month postoperation. [pre-op: 0.60$\pm$0.07, post-op: 0.56$\pm$0.06 p<0.01]

• Journal of Applied Reliability
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• v.15 no.1
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• pp.6-11
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• 2015

Maintenance plays an important role in keeping product availability, reliability and quality at an appropriate level. In this paper, two-types of maintenance policies are studied following the expiration of two-dimensional (2D) free replacement warranty. Both the fixed-maintenance-period policy and the variable-maintenance-period policy are based on a specified region of the warranty defined in terms of age and usage where all failures are minimally repaired. An accelerating failure time (AFT) model is used to allow for the effect of usage rate on product degradation. The maintenance model that arises following the expiration of 2D warranty is discussed. The expected cost rates per unit time from the user's point of view are formulated and the optimal maintenance policies are determined to minimize the expected cost rate to the user. Finally numerical examples are given to illustrate the optimal maintenance polices.