• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.417-420
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• 2008

In this study, the characteristics of strength development and hydration heat on high volume fly ash concrete(HVFAC) was experimentally investigated. Two levels of W/B were selected. Seven levels of fly ash replacement ratios and two levels of silica fume replacement ratios were adopted. In the concrete mix, the water content of $125kg/m^3$ was used, which is less than that of usual water content. As a result, it appeared that the compressive strength gradually decreased with increasing fly ash replacement ratio at the early age, but the difference of strength up to replacement ratio of 50% was little at the age of 91 days because of the pozzolanic reaction of fly ash. The effect of hydration heat reduction on the concrete was affected by the fly ash replacement ratio. When the replacement ratio was over 30%, the reduction efficiency of hydration heat was large.

• Journal of Korean Society for Quality Management
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• v.28 no.3
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• pp.53-58
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• 2000

In many cases, it is more practical and economical to repair a system than to replace the whole system or to perform a complete overhaul when it fails. The age replacement policy with minimal repair at failure is considered. The system is replaced every time its age reaches at $T_0$. For each intervening failure only minimal repair is done. The minimal repair times in a renewal period are increasing in the sense that the minimal repair times constitute a strictly increasing geometric process. The long-run expected cost rate Is obtained and the properties of the existence and the uniqueness of the optimal policy minimizing the long-run expected cost rate are derived.

• Journal of muscle and joint health
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• v.21 no.3
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• pp.206-214
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• 2014

Purpose: The aim of this study was to explore the elderly women patients' experience of treatment for total knee replacement. Methods: The participants in this study are 10 elderly women age 65 and over who were discharged after total knee replacement. The data were collected from August 5, to September 20, 2012, and it has been done by in-depth interview. Data were analyzed the phenomenological method of Colaizzi. Results: In this study, four categories were extracted: 'Suffering due to intolerable pain', 'A stable mind and body', 'Retrospection about old wounds', 'A desire for a new life'. Conclusion: This study provides the useful basic data to understand the elderly women patients who have experienced total knee replacement. Nursing intervention is required for pain control after surgery in order to improve the quality of life. In addition, nursing care through individual counseling and emotional support during the recovery period is very important. Therefore, various programs should be developed for elderly women patients to help their body recovery as well as psychological support after total knee replacement surgery.

• Journal of the military operations research society of Korea
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• v.29 no.2
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• pp.100-110
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• 2003

Equipment replacement policy may not be defined with certainty, because physical states of any technological system may not be determined with foresight. This paper presents Markov Decision Process(MDP) model for army equipment which is subject to the uncertainty of deterioration and ultimately to failure. The components of the MDP model is defined as follows: ⅰ) state is identified as the age of the equipment, ⅱ) actions are classified as 'keep' and 'replace', ⅲ) cost is defined as the expected cost per unit time associated with 'keep' and 'replace' actions, ⅳ) transition probability is derived from Weibull distribution. Using the MDP model, we can determine the optimal replacement policy for an army equipment replacement problem.

• The Journal of Korean Academy of Prosthodontics
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• v.8 no.1
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• pp.9-14
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• 1968

A total of 11,039 permanent missing teeth and their 2,696 prosthetic replaced teeth in 6,123 Korean patients were selected for this study, Analyzing the data according to age, sex, jaw and the location, following results were obtained. 1. Tooth mortality and replacement were higher in female than in male. 2. Replaced teeth were only 24 percent of missing teeth. 3. More teeth were extracted and replaced on lower jaw in young patients and on upper jaw in old patients. 4. There are no significant difference in right and left sides of both jaws in missing and replaced teeth, respectively. 5. First molar was the highest percentage in both mortality and replacement. 6. Upper tooth mortality and replacement were higher in anterior portion and lower in posterior portion.

• Journal of Chest Surgery
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• v.18 no.3
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• pp.383-390
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• 1985

108 cases of open heart surgery were done at our department in 1984. There were 58 male and 50 female patients ranging in age from 20 months to 52 years. 75 cases were congenital heart disease, and 33 cases were acquired heart disease. There were 75 congenital heart anomalies with 5 operative deaths [6.7%], consisting of 62 acyanotic cases with 2 deaths [3.2%] and 13 cases of cyanotic cases with 3 deaths [23.1]. In 33 patients of acquired valvular disease, 29 valves were implanted; 20 mitral valve replacement with 2 death [10%], 2 aortic valve replacement with 1 death [50%], 2 double valve replacement [MVR+AVR] and 2 open mitral commissurotomy plus aortic valve replacement with no death. Postoperative, Warfarin sodium was medicated with checking prothrombin time. Finally, the operative mortality was 9.2% in congenital anomaly, and 9.1% in acquired heart disease, overall mortality rate was 9.3%.

• Journal of the Korea Institute of Military Science and Technology
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• v.4 no.1
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• pp.170-176
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• 2001

An optimization problem to obtain the optimal replacement interval considering the salvage values is studied. The system is minimally repaired at failure and is replaced by new one at age T(periodic replacement policy with minimal repair of Barlow and Hunter〔2〕). Our model assumes that the time horizon associated with the number of replacements is random The total expected cost considering the salvage values with random time horizon is obtained and the optimal replacement interval minimizing the cost is found by numerical methods. Comparisons between non-considered salvage values and this case are made by a numerical example.

• Journal of Chest Surgery
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• v.21 no.2
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• pp.270-275
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• 1988

The results of the clinical observations on the 76 cases of the mitral valvular heart disease treated in the Department of Thoracic and Cardiovascular Surgery, Chung-nam National University Hospital during the period of 3 years from June, 1983 to July, 1986, are as follows: l. Of 76 cases, 43 were male and 33 were female with sex ratio of 1.3:1. 2. The age of the patient varied widely from 12 years of the youngest to 60 years of the oldest. 3. The main clinical symptoms on admission were dyspnea on exertion[100%], palpitation[42%], generalized weakness[29%], indigestion[18%], hemoptysis[16%]. 4. The preoperative functional levels according to NYHA classification were class II, III, IV in 9%, 63%, 28% respectively. 5. All 76 patients were operated on under direct vision using extracorporeal circulation, open mitral commissurotomy was done in 15 cases, mitral valve replacement in 37 cases, mitral valve replacement and aortic valve replacement in 11 cases, mitral valve replacement and tricuspid annuloplasty in 8 cases. 6. The operative mortality was 11.8% and results of the operation were good and excellent in 65 cases of survivors.

• Journal of Chest Surgery
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• v.27 no.12
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• pp.984-988
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• 1994

Between 1981 and 1992, 22 children from 1 to 15 years of age have undergone cardiac valve replacements at National medical center. The patients were composed of 14 males and 8 females and 7 patients had congenital heart disease and 15 patients had rheumatic heart disease. Three of these 15 patients have had second valve replacement due to prosthetic valve failure[PVF]. Single valve replacement were 20[Aortic 3 cases, Mitral 17 cases] and double valve replacments were 2. The overall mortality was 22.7 %. Actuarial survival rate was 77.28 $\pm$ 8.92 % and Complication free rate was 67.68$\pm$15.56%. The pediatric valve replacements can now be performed at a low operative risk although various problems are still remained and the choice of valve is prosthetic valve mainly due to its durability at the present time.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.11a
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• pp.773-776
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• 2006

This experimental study is the fundamental report to use the ternary concrete. This study performed to know physical properties of ternary concrete according to replacement ratio of pozzolanic admixtures and curing temperature conjugation. To investigate Strength development properties of according to replacement ratio of pozzolanic admixtures, both fly ash replaced on portland cement in 5, 10 and 15% weight ratios and blast furnace slag replaced on the portland cement in 5, 15, 20, 30 and 40% weigt ratios was used. Also this is studied fresh and hardened concrete properties in condition of curing temperature $10^{\circ}C\;and\;20^{\circ}C$. The followings are the summary of which concluded in this study. Considering the concrete cured over 28 days compressive strength, most replacement ratios of pozzolanic admixtures were higher than plain concrete that. Compressive strength development properties of ternary concrete according to curing temperature conjugation were similar except for early age.