• 호남수학학술지
• /
• 제38권3호
• /
• pp.661-674
• /
• 2016

In [15] they introduced a new finite element method for accurate numerical solutions of Poisson equations with corner singularities, which is useful for the problem with known stress intensity factor. They consider the Poisson equations with homogeneous Dirichlet boundary condition, compute the finite element solution using standard FEM and use the extraction formula to compute the stress intensity factor, then they pose a PDE with a regular solution by imposing the nonhomogeneous boundary condition using the computed stress intensity factor, which converges with optimal speed. From the solution we could get accurate solution just by adding the singular part. This approach works for the case when we have the accurate stress intensity factor. In this paper we consider Poisson equations with mixed boundary conditions and show the method depends the accrucy of the stress intensity factor by considering two algorithms.

• 한국물환경학회지
• /
• 제28권2호
• /
• pp.213-218
• /
• 2012

Abnormal dissolved oxygen concentration in aquatic habitat, both depletion and supersaturation, can be stress factor to aquatic animals. In this study the nationwide distribution of oxygen supersaturation was analyzed for three categories of streams (43 urban streams, 15 rural streams, and 14 forest streams) by using monitoring network data of the Korean Ministry of Environment. From the distribution analysis 30% of urban streams showed hyperoxic condition of eutrophic level, while no forest stream showed hyperoxic condition. The physiological effect of hyperoxia on fish was examined using two species of fish Zacco koreanus, which resulted in higher concentration of a stress hormone (cortisol) in fish exposed to hyperoxic concentration (196%) of oxygen. This study shows that hyperoxic condition is ubiquitous in urban and rural Korean streams, and it can be a stress factor to aquatic animals.

• 대한기계학회논문집B
• /
• 제25권11호
• /
• pp.1459-1466
• /
• 2001

A slip factor is defined as an empirical factor, which should be multiplied to theoretical energy transfer to estimate real work input of a centrifugal compressor. During the last century, researchers have tried to develop simple empirical models to predict the slip factor. However most of these models have been developed based only on design point data. Furthermore flow is assumed inviscid. As a result, these models often fail to predict the correct slip factor at off-design condition. In this study, various models for the slip factor were analysed and compared with experimental and numerical data at off-design conditions. As a result of this study, Wiesner's and Paeng and Chung's models are shown to be applicable for radial impeller, but all the models are found to be inappropriate for backswept impellers.

• 한국터널지하공간학회 논문집
• /
• 제16권2호
• /
• pp.125-133
• /
• 2014

본 연구에서는 지반 및 현장조건을 고려한 TBM 선정방법을 제시하였다. 지반, 환경, 가격조건별로 TBM 선정에 영향을 미치는 인자와 굴착장비를 선정 분류 하였다. 선정된 영향인자와 장비 간 가중치를 AHP기법을 적용하여 산정하였다. 선정된 영향인자의 분석결과 기본요소에서는 지반조건이 가장 중요한 영향요소로 확인되었으며, 세부요소로서 암반조건에서는 강도, 토사지반조건에서는 수압이 가장 중요한 인자로 확인되었다. 주변 환경조건에서는 시공성에 영향을 줄 수 있는 주변구조물 인접여부가 중요한 인자로 확인되었다. 마지막으로 도출된 각 영향인자별 가중치를 토대로 굴착현장에 적용 가능한 TBM을 선정하고 도출결과와 실제 현장에 적용된 장비의 비교를 통하여 본 연구에서 제안하는 방법에 대한 검증이 이루어 졌다.

• 동력기계공학회지
• /
• 제18권1호
• /
• pp.32-37
• /
• 2014

In this study, the optimum design process of an indoor package air-conditioner (PAC) was implemented by Taguchi method. The goal of this study is to obtain the best set condition of each control factor composing of an indoor PAC. The number of revolution of a double inlet sirocco fan installed in an indoor PAC was measured by the orthogonal array of $L_{18}(2^3{\times}3^4)$ and analysed by using the-smaller- the-better characteristic among the static characteristic analyses. As a result, the optimum condition of an indoor PAC was found as a set of when the cost of production, assembling and working conditions were considered. Moreover, the number of revolution of a double-inlet sirocco fan used for an optimum condition was reduced about 8.5% more than that of a standard condition for the target flowrate of $18.5m^3/min$.

• 대한산업공학회지
• /
• 제24권3호
• /
• pp.367-379
• /
• 1998

This paper considers two modes of partially accelerated life tests for items having Weibull lifetime distributions. In a use-to-acclerated mode each item is first run at use condition and, if it does not fail for a specified time, then it is run at accelerated condition until a predetermined censoring time. In an accelerated-to-use mode each one is first run at accelerated condition and, if it does not fail for a specified time, then it is run at use condition. Maximum likelihood estimators of the parameters of the lifetime distribution at use condition, and the 'acceleration factor' are obtained. The stress change time for each mode is determined to minimize the asymptotic variance of the acceleration factor, and the two modes are compared. For selected values of the design parameters the optimum plans are obtained, and the effects of the incorrect pre-estimates of the design parameters are investigated. Minimizing the generalized asymptotic variance of the estimators of the model parameters is also considered as an optimality criterion.

• 해양환경안전학회지
• /
• 제21권2호
• /
• pp.171-178
• /
• 2015

본 연구는 제한속력 설정 모델 개발을 위한 1차 연구로서 제한속력 설정 시 고려요소에는 어떤 것이 있으며, 각 요소별 중요도는 얼마나 되는지에 대한 연구의 결과이다. 고려요소 식별과 중요도 산정을 위해 델파이(Delphi)기법과 AHP(Analytic Hierarchy Process)기법을 이용하였다. 델파이 설문은 3차에 걸쳐 수행하였고 3차에 걸친 설문을 통해 5개 상위요소(Level 1)와 23개 하위요소(Level 2)가 식별되었다. 3차 델파이 설문과정에서 내용타당도비율(CVR)값이 0.4~1.0 범위에 있으면 제한속력 설정 시 고려요소로서 반영하였고 0.4 미만의 값은 고려요소에서 제외하였다. 2차 델파이 설문과정에서 33개 고려요소가 식별되었으나 3차 설문을 통해 23개 항목으로 축소되었다. 델파이 3차 분석을 통해 얻은 23개 항목을 대상으로 AHP 설문을 수행하였다. AHP 설문 결과, 5개 상위요소(Level 1)에 대한 중요도는 교통조건이 가장 중요한 요소로 평가되었고, 선박조건, 항로조건, 자연조건, 외부지원 및 기타 조건 순으로 평가되었다. 23개 하위요소 중에서 시정이 가장 중요(1위)하다고 평가되었으며, 선박조종성능, 항로 내 수중장애물, 교통량 및 밀도, 통항선박간 거리, 타효가능속력, 조류 순으로 평가되었다.

• 한국펄프종이공학회:학술대회논문집
• /
• 한국펄프종이공학회 2005년도 추계학술발표논문집
• /
• pp.259-263
• /
• 2005

This study was performed to introduce recently developed Polyvinylamine as a wet-end process improving aids and paper properties improving aids. As a retention and drainage aids, cationicity of Polyvinylamine was a very important factor of BCTMP and ONP stock condition. As a dry tensile strength aids, The hydrogen bond of acrylamide functionality and hydroxyl functionality of the pulp was a very important factor of LBKP stock condition and cationicity of Polyvinylamine was a very important factor of BCTMP and ONP stock condition.

• 품질경영학회지
• /
• 제42권1호
• /
• pp.63-70
• /
• 2014

Purpose: This article introduces a case study of using Taguchi Method to improve lecture satisfaction. Developed by Taguchi Genichi, this method has its strength in finding the control factor that is robust against noise factor. Finding the condition for such control factor has an effect of reducing the dispersion of the Lecture satisfaction. Methods: There are various factors in university classrooms. The factors which influenced the Lecture Satisfaction are analyzed by control factors and noise factors, control factors which is controllable are lecture completeness and thoroughly test the degree of supervision and noise factors which is not controllable is degree of physical and psychological Lecturer tired, then the experiment is conducted as guided by Taguchi's experimental design, one semester are experimented by eight professor with 2 classes, after discussion of the results the optimal lecture condition is suggested. Results: To improve Lecture Satisfaction under noise factor of physical and psychological Lecturer tired, optimal condition are that lecture completeness have scenario note during lecture and thoroughly test the degree of supervision have two proctors during test. Conclusion: In this paper, we have succession case by applying Taguchi methods in Lecture Satisfaction. We can apply to improve service by applying the Taguchi methods. In the future we hope to have many succession cases.

• 제어로봇시스템학회:학술대회논문집
• /
• 제어로봇시스템학회 2003년도 ICCAS
• /
• pp.2121-2125
• /
• 2003

This paper proposes a fast distributed constrained power control (FDCPC) with non-stationary relaxation factor to next power update in CDMA cellular power control system. We review unconstrained control algorithms, the distributed power control (DPC), unconstrained second order power control (USOPC) and DPC with stationary relaxation factor (DPCSRF). Under the unconstrained condition, the convergence analysis shows theoretically that the convergence rate of DPC is the fastest one. However, under the constrained control algorithms, DCPC is not the fastest one any more because of transmission power constraint. To improve the convergence speed, the DCPC with non-stationary relaxation factor (FDCPC) are proposed. Under the constrained condition, the convergence rate of FDCPC outperforms that of DCPC and CSOPC.