• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2008년도 춘계 학술발표회 제20권1호
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• pp.417-420
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• 2008

본 연구에서는 플라이애쉬가 다량 치환된 콘크리트 강도 발현과 수화열 특성에 대하여 연구를 수행하였다. 2수준의 W/B와 7수준의 플라이애쉬 치환률 및 2수준의 실리카흄 치환율을 실험 변수로 선택하였다. 콘크리트 배합에서 단위수량은 $125kg/m^3$으로 고정하였다. 결과로서 초기 재령에서는 플라이애쉬 치환율이 증가하면서 압축강도가 점진적으로 감소하는 경향을 나타내었다. 그러나 재령 91일에서는 50%의 플라이애쉬 치환률까지 압축강도가 큰 차이가 없는 것으로 나타났다. 그리고 수화열 저감 효과는 플라이애쉬 치환율에 영향을 받는 것으로 나타났다. 플라이애쉬 치환율이 30% 이상일 때 수화열 저감 효율이 더 좋은 것으로 나타났다.

• 품질경영학회지
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• 제28권3호
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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.

• 근관절건강학회지
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• 제21권3호
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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.

• 한국국방경영분석학회지
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• 제29권2호
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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.

• 대한치과보철학회지
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• 제8권1호
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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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• 제18권3호
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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%.

• 한국군사과학기술학회지
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• 제4권1호
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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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• 제21권2호
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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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• 제27권12호
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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.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2006년도 추계 학술발표회 논문집
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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.