• 천문학회지
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• 제17권1호
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• pp.1-14
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• 1984

Analyses of an integrated form $N(\tau)={\int}_{\tau}^{\infty}n(\tau)d{\tau}$ of the distribution of cluster ages, rather than its differential form $n(\tau)$, demonstrate that the observed distribution has clusters older than about 500 million years in a significant excess over theoretical model distributions. Considerations on cluster disruption processes show that a single disruption time-scale, frequently employed by current theoretical models, is no longer an adequate parameter for describing survival probability of clusters over wide age range, because different initial conditions of these clusters produce corresponding spreads in their lifetimes. To take into account for the spread in initial conditions, we have introduced an age-dependent disruption time, and deduced its age-dependence from the present-day age distribution of clusters. Results show a distinct two-stage variation: The newly introduced disruption time stays constant at about 50 million years for clusters younger than about 100 million years, while for clusters older than that it increases monotonically with the cluster age. This leads us to conclude that clusters experience different types of disrupting causes as they get old.

• Journal of Chest Surgery
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• 제17권2호
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• pp.212-222
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• 1984

A total of and consecutive 291 patients underwent isolated mitral valve replacement using the Ionescu-Shiley bovine pericardial xenograft valve during the 5-year period between October 1978 and June 1983. Thirty-two patients were the children under 15 years of age. There were 15 deaths within 30 days after surgery [operative mortality, 5.2%]. All early survivors except 6 children were placed on the long-term oral anticoagulation longer than postoperative 3 months. A total follow-up period extended for 398.2 patient-years, and 12 patients died [late mortality, 4.1%, or 3.0%/patient- year]. Ten patients experienced the thromboembolic complication [2.51%/patient-year], occurring in 8 patients within the first 3 postoperative months, and 4 died. Three patients had the late prosthetic valve endocarditis [0.75%/patient-year] and 2 died. The incidence of overall valve failure according to the criteria was 3.01%/patient-year, or 12 patients, and 2 had replacement of the failed bioprostheses [primary tissue failure, 0.5%/patient-year]. The long-term survival rate was 87.8%\ulcorner2.6% at 5 years postoperatively, and 84% of the late survivors were in NYHA Class I at the end of the follow- up. The probability remaining free from thromboembolism and overall valve failure was 89.8%\ulcorner6.3% and 81.2%\ulcorner.8% at 5 years respectively. These clinical results confirm the safety of mitral valve replacement. The only remaining clinical problem is the structural and functional durability of the bovine pericardial xenograft valve, and its use in young patients may be stopped in preference to the mechanical prosthetic valves.

• 한국정밀공학회지
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• 제13권10호
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• pp.36-45
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• 1996

The precise estimation of the reliability and life of the Ravigneaux planetary gear train used in an automatic transmission is necessary in order to enable accurate material and geometric properties to reliability distrobution and the number of load cycles at failure. These are critical for the proba- bilistic design of complex planetary gear system as Ravigneaux type particularly during various gear ratios. The Ravigneaux planetary gear train has five gears, such as a forward and a reverse sun gear, a short and a long pinion, and an annulus gear. In this paper, the Ravigneaux gear system is analyzed to figure out the reliablity distribution. i.e. the probability of survival in the system without its overhaul. First, the reliablity method based on the Weibull distribution is used in conjuction with the Palmgren's model to predict both the individual reliabilities of its components and the nimber of load cycles when the system failed. Then using the presented method, the life of the Ravigneaux gear system can be determined. Alwo the different design parameters such as tooth face width, material property, and Weibull exponent are applied and reached to optimal ones. Thus, the precise evaluation of the reliability and life of the Ravigneaux planetary gear train used in an automatic transmission can be effectively carried out.

• 지식경영연구
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• 제12권3호
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• pp.73-96
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• 2011

Recent market saturation makes the local retailers consider an attempt to innovate the market with the retailer's brand. This is the retailers' efforts to expand the market control through the enhancement of private brands. As the competition among manufacturers extends to the competition between manufacturers and retailers, the marketing knowledges of manufacturers need to be diversified to the ones that can be applied to the manufacturers and retailers due to their bilateral competition. This research concentrates on the customer acquisition strategy (attack strategy) and customer retention strategy (defense strategy) in the place of both sides of manufacturers and retailers. Also this research targets to develop the differential marketing strategies for target market's National Brand(NB)/Private Brand(PB) purchase by analyzing individual customer's purchase probability on repurchase and switch-purchase of NB and PB. This study is based on the data of frequently consumed product, tomato ketchup on scanner panel from the ERIM data of University of Chicago, USA. This study compares and analyzes the NB and PB repurchases and switch-purchase of 4 types. The comparisons provide the informations that which factors should be managed for the attack strategy, the defense strategy, and the differential marketing strategies both for manufacturers and retailers. This research is expected to contribute on cumulating the industrial knowledges of retailers' and manufacturers' survival strategy, expecially focusing on the effect of marketing factors and consumer-characteristic factors.

• 동력기계공학회지
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• 제12권4호
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• pp.64-71
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• 2008

This study is on pedestrian protection device using pneumatic cylinder and simple link mechanism when vehicle collide with pedestrian. This study ensured the safety space between engine and hood after it applies to simple link mechanism and pneumatic cylinder. It can absorb the damage which measure the specific device if vehicle collide with pedestrian. Combination of simple link mechanism and pneumatic cylinder was more superior than the present pedestrian protection device. Simple link mechanism could confirm superior height and survival probability than when only cylinder operated. It also ensured enough space between engine and hood. And if a cylinder is not working because of old cylinder, poor repair or damage of accident vertical cylinder would be difficult to execute because there exists the irregular space between engine and hood. If simple link mechanism operates with only one cylinder it could ensure the regular space because simple link mechanism set up at the middle of hood. So this device could confirm high safety for pedestrian.

• 한국화재소방학회논문지
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• 제30권4호
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• pp.128-134
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• 2016

구급서비스의 소요 시간, 특히 반응시간은 생존 확률을 향상시키고 후유 장해를 감소시킬 수 있다는 점에서 구급서비스의 품질 관리를 위한 중요한 지표로 활용되고 있다. 이에 본 연구에서는 2011년부터 2014년까지 4년 동안 ${\bigcirc}{\bigcirc}$시의 신고 접수, 출동, 구급활동 자료를 이용해 환자 특성, 주증상 등을 고려한 구급서비스의 시간(time interval)을 분석하였다. 구급서비스의 시간에 대한 정의를 세분화하고 각각의 소요 시간에 미치는 다양한 경제사회적 요인이나 지역적 특성을 분석하여 효율적으로 관리할 수 있다면 구급서비스의 품질은 크게 제고될 것으로 기대 된다.

• 한국강구조학회 논문집
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• 제16권5호통권72호
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• pp.705-712
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• 2004

콘크리트에 강관을 매입하여 만든 핀컵의 역학적 거동을 파악하기 위해 재하 시험을 수행하였다. 핀컵에 핀을 각기 다른 깊이로 근입하고, 핀의 근입 방향에 직각인 방향으로 변위가 일정한 속도로 증가하도록 변위를 제어하면서 하중을 증가시켰다. 시험을 통해 관찰한 핀컵 강관과 핀컵 주변의 콘크리트 변형 및 파괴 형태를 바탕으로 계산모델을 구성하고, 핀컵의 역학적 거동을 예측할 수 있는 계산식을 유도하였다. 제안된 계산식과 시험결과는 서로 좋은 관련성을 보이며, 일정한 범위 내에 분포하는 것으로 나타났다. 시험값과 계산값을 비교한 결과 핀컵 최대 저항력의 평균과 생존확률 95% 값은 각각 계산식에 보정계수 1.01과 0.92를 곱한 값과 같은 것으로 나타났다.

• Journal of Chest Surgery
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• 제25권1호
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• pp.57-65
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• 1992

St.Jude Medical cardiac valve replacement was performed in 322 patients: 191 had mitral, 58 had aortic, 72 had double valve and 3 had tricuspid valve replacement. Motality rate in early period was 2.8%[9 patients]. The most common cause of early death was low cardic output syndrome. Follow up extended from 1 to 90 months[mean: 34 months] in 292 patients among 313 in all surviving patients [93.6%]. There were thrombolic complications in eighteen patients. The probability of free from thromboembolism at 5 yerars in MVR, AVR and DVR were 84.7%, 91.8% and 90.2% respectively. And also, actuarial event free rate at 5 years in MVR, AVR and DVR were 80.1%, 82.2%, and 81.4% respectively. There were fourteen late death during follow up period: six from thromboembolism, one from hemorrhage and the others from non valve related -or unknown complications. The acturial survival rate at 5 years were 93.1% in mitral, 92.1% in aortic and 97.1% in double valve replacement. In conclusion, the performance of the St. Jude Mecanical valve compares most favorably with other artificial valves. But it remains still hazards of mechanical prosthesis such as thromboembolism and anticoagulant related hemorrhage.

• 한국자동차공학회논문집
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• 제6권4호
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• pp.76-85
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• 1998

Recently, Genetic Algorithm(GA) is widely adopted into a search procedure for structural optimization, which is a stochastic direct search strategy that mimics the process of genetic evolution. This methods consist of three genetics operations maned selection, crossover and mutation. Contrast to traditional optimal design techniques which use design sensitivity analysis results, GA, being zero-order method, is very simple. So, they can be easily applicable to wide area of design optimization problems. Also, owing to multi-point search procedure, they have higher probability of converge to global optimum compared to traditional techniques which take one-point search method. In this study, a method of finding the optimum values of suspension parameters is proposed by using the GA. And vehicle is modelled as planar vehicle having 5 degree-of-freedom. The generalized coordinates are vertical motion of passenger seat, sprung mass and front and rear unsprung mass and rotate(pitch) motion of sprung mass. For rapid converge and precluding local optimum, share function which distribute chromosomes over design bound is introduced. Elitist survival model, remainder stochastic sampling without replacement method, multi-point crossover method are adopted. In the sight of the improvement of ride comfort, good result can be obtained in 5-D.O.F. vehicle model by using GA.

• 한국태양에너지학회:학술대회논문집
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• 한국태양에너지학회 2011년도 춘계학술발표대회 논문집
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• pp.48-53
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• 2011

In this study, it is to verify the applicability for a simplified model(IEC61400-2, Design Require-ments for Small Wind Turbines, 2006-03) is the international standard is used to the structural design. In the design process of a wind turbine, the safety of a designed wind turbine is one of the most important factors. The simplified model can be used to determine the design load for small wind turbines. So, this paper has been re-evaluated a small wind turbine design loads that produced already. As a result, the material characteristic value(Rchar) of Blade, Rotor shaft and the tower are $90E6[N/m^2]$, $441E6[N/m^2]$ and $94E6[N/m^2]$. Therefore, the value of the applied safety factor to each part of the survival probability of 95% are satisfied.