• 한국건축시공학회지
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• 제13권2호
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• pp.139-147
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• 2013

The purpose of this study was to investigate the durability performance of concrete that includes rice husk ash. Chloride diffusion coefficient obtained through a rapid chloride penetration test and depth of $CO_2$ penetration obtained through a rapid carbonation test were used to evaluate latent durability. Durability characteristics for rice husk ash replacement and age were determined. Through the experiment, it was found that when the replacement ratio of rice husk ash was increased from 0% to 10%, the compressive strength of concrete containing rice husk ash was similar to that of concrete containing silica fume. This shows that the durability performance of concrete containing rice husk is excellent compared to other concretes containing admixtures.

• Journal of Chest Surgery
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• 제27권1호
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• pp.31-35
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• 1994

Dissecting aortic aneurysm is a life threatening condition which necessitates prompt diagnosis and management. Between January 1987 and September 1993,58 patients was admitted to our department. Mean age at admission was 53 years.[range 25-82]. Clinical findings included chest pain in 48 cases[83%],renal failure in 12[20%],aortic insufficiency in 11[19%] and stroke in 9[15%]. Predisposing factors were hypertension in 50 cases[86%],Marfan`s syndrome in 6[10%] and diabetes melitus in 1 [2%]. 23 patients[ type A 13,type B 10 ] underwent surgical treatment. Surgical technique for type A included graft replacement of ascending aorta in 7 cases,graft replacement and aortic valve resuspension in 3,and Bentall`s operation in 3 cases. Type B patients were operated when specific indications applied. There were three [Two in type A and 1 in type B] deaths in the operation group and nine [ 5 in type A and 4 in type B] deaths in the medical group. These results support our current policy in the treatment of dissecting aortic aneurysm.

• 혜화의학회지
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• 제13권2호
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• pp.1-10
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• 2004

During the reproductive years, the most common uterine myoma are benign, but the possibility of malignancy must be considered. Generally uterine myoma are also benign, and two-thirds of these occur in women between 30 and 45 years of age. Which produce few of only mild, nonspecific symptoms. The most common symptoms include abdominal pain or discomfort, low abdominal pressure sensation, hypermenorrhea and urinary symptoms comprise. The treatment of uterine myoma is just observation, operation and taking the hormone replacement therapy in western medicine.This study is performed to evaluate the effectiveness of Resonance Therapy and herb-med on uterine myoma. After this treatment, the size of the uterine myoma were reduced with a significant data or dismissed. So it indicates Resonance Therapy and herb-med is effective on the patient with uterine myoma, but continuous observation and study are needed.

• Computers and Concrete
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• 제7권1호
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• pp.17-38
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• 2010

This research aimed to investigate the influence of high-volume mineral admixtures (MAs), i.e., fly ash and slag, on the hydration characteristics and microstructures of cement pastes. Degree of cement hydration was quantified by the loss-on-ignition technique and degree of pozzolanic reaction was determined by a selective dissolution method. The influence of MAs on the pore structure of paste was measured by mercury intrusion porosimetry. The results showed that the hydration properties of the blended pastes were a function of water to binder ratio, cement replacement level by MAs, and curing age. Pastes containing fly ash exhibited strongly reduced early strength, especially for mix with 45% fly ash. Moreover, at a similar cement replacement level, slag incorporated cement paste showed higher degrees of cement hydration and pozzolanic reaction than that of fly ash incorporated cement paste. Thus, the present study demonstrates that high substitution rates of slag for cement result in better effects on the short- and long-term hydration properties of cement pastes.

• Journal of Chest Surgery
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• 제27권6호
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• pp.455-459
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• 1994

We experienced 20 cases of acquired aortic diseases during last 1 year [Sep. 1992-Aug. 1993] with newly developed surgical strategies. There were 13 cases[65%] of aortic dissections, 5 cases[25%] of aortic aneurysms and 2 cases of Takayasu arteritis with mean age of 56 + 16 years[range:5-78].In ten cases of patients requiring ascending aortic replacement, femoral artery and femoral vein &/or RA auricle were used as cannulation site. With deep hypothermic circulatory arrest and retrograde cerebral perfusion of cold oxygenated blood via SVC, we can replace the ascending aorta and part of arch if necessary. The mean duration of circulatory arrest was 30 minutes[17-45 min]. In 5 cases of patients who requiring descending and thoracoabdominal aorta replacement, we used simple aortic crossclamping under normothermia with no heparin. The mean duration of aortic crossclamping was 37 minutes[25-50 min].The results of operation were as follow:Operative mortality[2 cases, 10%], delayed cerebral infarct[1], low extremity weakness[1] and intraoperative myocardial infarct[1]. There are no delayed complication or mortality as yet.

• 한국국방경영분석학회지
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• 제16권1호
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• pp.142-150
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• 1990

This paper combines research in the areas of replacement and machine interference. Although over the past three decades there has been a great deal of research in the area of optimal replacement for stochastically deteriorating equipment and research dealing with machine interference problems : there has been a lack of research when these two areas are combined. However, the melding of these two well-known areas yields a very practical problem which demands theoretical investigation. In this paper we derive the steady state probabilities with a control limit policy for a two-machine one repairman problem. The control policy is a simple age dependent control described by the control limit, $t^{*}$. Once $t^{*}$ is fixed, the steady state probabilites that one, two, and no machines are working will be obtained.

• Journal of Chest Surgery
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• 제51권6호
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• pp.395-398
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• 2018

Neo-aortic insufficiency associated with root enlargement following an arterial switch operation is a serious late complication. To achieve successful surgical correction of this condition, multiple factors should be considered, including the individual patient's anatomy, the challenging nature of the redo procedure, and the patient's young age. However, limited publications have described the use of valve-sparing techniques for the treatment of neo-aortic insufficiency associated with root enlargement following an arterial switch operation. Herein, we report our recent experience of a valve-sparing aortic root procedure with ascending aorta and hemiarch replacement despite the presence of a discrepancy in leaflet size and nearby severe adhesions.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2020년도 봄 학술논문 발표대회
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• pp.62-63
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• 2020

In this study, fundamental properties of high strength concrete containing blast furnace slag are investigated analyzed according to CBS-Dust replacement rate. As the CBS-Dust replacement rate increased, air content, fluidity and strength decreased, but concrete with 5~10 % of CBS-Dust showed excellent compressive strength in its early age. Therefore, 5~10 % substitution of CBS-Dust on high strength concrete containing blast furnace slag will have a positive effect on reducing waste disposal cost and improving the strength.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2002년도 가을 학술발표회 논문집
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• pp.11-16
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• 2002

The production of Portland cement involves maximum use of resources and energy, which leads to destruction of tile ecological environment, raising in serious environmental issues such as acid rain and the greenhouse effect. In order to combat the arising problems associated with Portland cement, it thus is necessary that a non-clinker cement should be developed. In this study, non-clinker cement is produced by blending granulate blast furnace slag with phosphogypsum as main materials, and small amounts of hydrate lime or waste lime as activators. This paper aims to investigate compressive strength according to various condition of mixing ratio, blame, W/C ratio and curing temperature. Compressive strength of non-clinker cement increases continuously according to increase in curing age and blain. Although the compressive strength is fairly comparable to that of OPC in the early curing age, it reaches a higher lever in the later age than that of OPC due to the optimum mixing ratio and the continuous reaction of slag and phosphogypsum. Results obtained from this study have shown that non-clinker cement could be used as a replacement of OPC.

• 품질경영학회지
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• 제25권3호
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• pp.86-95
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• 1997

This paper considers a repairable system, which is maintained preventively at periodic times and is minimally repaired at each failure. Most preventive maintenance policies for such repairable systems assume that the cost of minimal repair is constant regardless of its age at failure. However, it is more practical to consider the situations where the cost of minimal repair is dependent not only on its age at failue, but also on the number of preventive maintenance carried out prior to its failure. We consider the preventive maintenance carried out prior to its failure. We consider the preventive maintenance policy with age-dependent minimal repair cost. The optimal policies which minimize the expected cost rate over an infinite time span are discussed. We obtain the optimal period and number of preventive maintenance prior to replacement of the system.