• 한국농공학회논문집
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• 제52권5호
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• pp.53-60
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• 2010

The effects of blast furnace slag, hwang-toh, and reinforcing fiber on the physical and mechanical properties of porous concrete using blast furnace slag coarse aggregates have been evaluated in this study. The effect of the depending on replacement ratio of blast furnace slag to cement was investigated such that the replacement ratio was varied to 0 %, 25 % and 50 %. Also, the replacement ratios of hwang-toh were 0, 20 and 30 %. The polyvinyl alcohol fiber was used for the reinforcing fiber. A series of pH, unit mass, and void ratio tests have been performed to study the physical properties of the porous concrete using blast furnace slag coarse aggregates with the polyvinyl alcohol fiber and the replacement ratios of blast furnace slag, hwang-toh, while a series of compressive tests have been performed to evaluate the strength property depending on polyvinyl alcohol fiber and the replacement ratios of blast furnace slag, hwang-toh. The test results indicated that the physical and mechanical properties of porous concrete using blast furnace slag coarse aggregates is affected by the replacement ratio of blast furnace slag, and the fiber contents. According to the tests with polyvinyl alcohol fiber contents, the void ratio was decreased and the compressive strength was upgraded.

• 한국통신학회논문지
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• 제40권6호
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• pp.1091-1101
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• 2015

오랜기간 컴퓨터 분야의 연구주제였던 캐시 메커니즘은 네트워크 영역에서 웹 캐시로 응용되었다. 응답시간 감소, 네트워크 자원 절약 등의 다양한 이점을 갖는 웹 캐시는 교체정책에 의해 성능이 좌우되므로, 보다 나은 교체정책의 설계를 위해 웹 캐시가 운용되는 환경에 대한 분석과 고찰이 필수적이다. 따라서 과거에 비해 급속도로 다변화된 현재 웹 환경에서는 그러한 변화를 반영할 수 있는 교체정책이 요구된다. 따라서 본 논문에서는 현재 웹 환경의 특성을 규정하고, 이에 적합한 캐시 교체정책을 설계하고 평가한다.

• 벤처창업연구
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• 제9권2호
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• pp.81-86
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• 2014

본 논문에서는 그룹교체 정책과 예비품 재고정책을 동시에 고려하여 최적화하는 방안을 제시한다. 일반적으로 보전정책들은 예비품의 재고가 늘 가용하다고 가정하고 있으나 예비품의 재고 확보 여부에 의해 보전활동은 영향을 받을 수밖에 없다. 동일한 여러 유닛들이 동시에 운용될 때 이용되는 그룹교체정책을 바탕으로 이를 지원하기 위한 최적 재고수준을 결정한다. 일정한 개수의 유닛이 고장 나는 시점에서 그룹교체를 수행한다. 예비품의 재고는 일정 횟수의 그룹교체를 할 만큼 주문하여 유지한다. 보전비용과 재고비용 등 운용비용을 최소화할 수 있는 최적의 그룹교체 주기와 재고수준을 구한다.

• Geomechanics and Engineering
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• 제23권4호
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• pp.365-379
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• 2020

One of the leading causes for the damage of various underground structures during an earthquake is soil liquefaction, and among this liquefaction-induced uplift of these structures is a major concern. In this study, finite-difference modelling is carried out to study the liquefaction-induced uplift of an underground structure of 5 m diameter (D) with and without the replacement of the in-situ fine sand around the structure with the coarse sand. Soil replacements are carried out by three methods: replacement of soil above the structure, around the structure, and below the structure. The soil behaviour is represented using the elastic-perfectly plastic Mohr-Coulomb model, where the pore pressures were computed using Finn-Byrne formulation. The predicted pore pressure and uplift of the structure due to sinusoidal input motion were validated with the centrifuge tests reported in the literature. Based on numerical studies, an empirical equation is developed for the determination of liquefaction-induced maximum uplift of the underground structure without replacement of the in-situ sand. It is found that the replacement of soil around the structure with 2D width and spacing of D can reduce the maximum uplift by 50%.

• 한국구조물진단유지관리공학회 논문집
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• 제21권4호
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• pp.61-68
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• 2017

교량 바닥판은 대형 차량 및 제설제와 같은 다양한 환경 요인으로 인해 급속히 악화되는 부재이다. 한국에 건설된 교량의 수명이 길어짐에 따라 교량 바닥판의 교체 수요가 증가 할 것으로 예상된다. 다른 국가에서는 프리 캐스트 바닥판을 이용한 급속 교량 건설 기술이 열화된 교량 바닥판의 교체 수요 대응을 위해 적극적으로 사용되고 있다. 본 연구에서는 국내 교량 바닥판의 상태평가 데이터를 수집 및 분석하여 교량 바닥판 열화 모델을 제안 하였다. 또한 교량 규모의 관점에서 열화된 교량 바닥판의 미래 대체 수요를 예측하였다.

• Journal of Chest Surgery
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• 제26권6호
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• pp.457-462
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• 1993

We retrospectively studied 34 patients who underwent operations of ascending aortic aneurysm and aortic valve replacement from August 1979 to July 1992 at the Yonsei Cardiovascular Center. Eight patients underwent supracoroanry non-composite graft replacement and separate aortic valve replacement[group I]. Twenty six patients underwent valved composite graft replacement with reimplantation of coronary arteries[group II]. Two cases in group II died within 1 month after the operation. Among the 32 survivors 28 patients have been followed up for an average of 59 months ranging from 1 months to 159 months. During the follow up periods, a pseudoaneurysm around the ascending aorta and a newly developed dissecting aneurysm in remaining aorta were noted in group II. There were 6 late deaths: 2 cases in group I and 4 cases in group II. Three cases among the 6 late deaths have stigmata of Marfan`s syndrome[1 cases in group I and 2 case in group II]. There was no statistically significant difference in actuarial survival rates between group I and group II[p > 0.05]. This study suggests that non-composite supracoronary graft interposition with separate aortic valve replacement is a safe surgical technique in patients who have normal aortic annulus and normal position of coronary ostia. However in degenerative disease such as cystic medial necrosis, composite graft replacement is recommended because this procedure eliminates entire abnormal tissue.But it seems to be important that the suture technique and strict follow-up in patients with diseased aortic wall.

• 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.

• 보건행정학회지
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• 제30권1호
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• pp.62-71
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• 2020

Background: The purpose of this study is to analyze the current status and factors of elderly patients' hospitalization for hip replacement, knee replacement, and general spine surgery. Methods: National health insurance data in 2018 was provided by the National Health Insurance Service. We used multiple regression to analyze factors associated with the medical utilization of hip replacement, knee replacement, and general spine surgery in elderly patients over 65 years old. The dependent variables are the length of stay and total health expenditure. The independent variables are the demographic-social factors (sex, age, region, insurance type, income level) and surgery-related factors (institution type, location of the hospital, surgery classification). Results: The most common factor affecting surgery was the location of medical institutions. Compared with the medical institutions located in metropolitan, the length of stay in rural medical institutions was higher and total health expenditure was lower. The lower quartile of income, the higher the length of stay and total health expenditure. In addition, the variables of age, type of health insurance, and type of medical institution were statistically significant. Conclusion: In this study, we confirmed the effect of sociodemographic factors and medical institution factors on the Healthcare Utilization of spinal and joint surgery.

• 한국산업정보학회논문지
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• 제20권5호
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• pp.45-52
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• 2015

하이브리드 하드디스크는 저전력이면서 마그네틱 하드디스크에 비해 읽기 성능이 우수하다. 이 디스크의 플래시메모리에는 지역성이 높은 블록이 저장되므로 효율적인 블록 교체 기법이 필요하다. 블록 교체에는 크기, 지역성, 빈도 등 다양한 요인에 의해 결정되므로 일종의 다중 기준 결정 모델로 정의될 수 있다. 이 문제를 해결하기 위해 본 연구는 AHP (Analytic Hierarchy Process) 모델을 적용하여 효율적인 블록 교체 기법을 제시한다. 실험의 효율성을 검증하기 위하여 철저한 시뮬레이션을 수행한 결과 일반응용 프로그램의 응답성뿐만 아니라 부트 시간이 단축됨을 확인하였다.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2016년도 춘계 학술논문 발표대회
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• pp.30-31
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• 2016

As the treatments of many kinds of explosive objects increase recently, it is in the trend that explosion accidents increase. Thus, many studies on HPFRCC (High-performance Fiber-reinforced Cement Composites) whose ductility is enhanced are being conducted actively in order to minimize the damages from explosion accidents. However, HPFRCC, the self-shrinkage of HPFRCC is on the rise as a problem since it becomes ultra-high strengthened by using low W/B. Thus, in this study, it is intended to evaluate the capacity for reducing the self-shrinkage of HPFRCC depending on some changes of ERCO(Emulsified Refined Cooking Oil) replacement ratio and the fiber replacement ratio between some short steel fibers (SS) and some long organic fibers (OL). As a result, it was found that some excellent effects are exerted since the self-shrinkage was reduced a lot as the ERCO replacement ratio increases and the fiber replacement ratio of SS rather than OL increases.