• 한국지반공학회논문집
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• 제22권6호
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• pp.51-61
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• 2006

말뚝-지반의 상호거동과 다양한 설계변수들의 불확실성을 고려한 축하중을 받는 단말뚝의 위험도를 정량화하기 위하여 효율적이고 정확한 복합 신뢰성해석 기법이 본 논문에서 제안되었다. 제안된 신뢰성해석 기법은 응답면기법, 유한차분법, 일차신뢰도법과 반복 선형보간기법의 개념들을 지능적으로 결합하였다. 단말뚝-지반계의 확정적 해석을 위해서 하중전이법과 유한차분법을 통합하였다. 하중조건, 말뚝의 재료와 단면특성, 그리고 지반특성과 관련된 불확실성을 명확하게 고려하였다. 말뚝과 지반의 사용성 한계상태 및 강도 한계상태에 대한 위험도를 평가하였다. 축하중을 받는 사실적인 말뚝-지반계의 안전성평가에 대한 제안기법의 적용성, 정확성 및 효율성을 몬테카를로 시뮬레이션의 결과와 비교함으로써 검증하였다.

• 한국방사선학회논문지
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• 제6권3호
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• pp.159-166
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• 2012

본 연구의 목적은 방사선의 사업적 이용에 따른 방사선발생장치 또는 방사성동위원소 등(이하 방사성동위원소 등)을 운용하는 방사선작업종사자를 대상으로 방사선안전관리와 관련된 지식의 설문 조사하고 이를 체계적으로 추이분석 함으로서 방사선 이용시설 등의 방사선안전 문화를 정착시키기 위함에 있다. 연구 방법은 2011년 08월 01일 부터 09월 05일 까지 861 명의 방사선 종사자를 대상으로 설문 조사를 하였다. 분석 방법으로 설문 응답자의 일반적인 특성과 기관정보는 빈도 분석을 하였으며 방사선안전관리에 대한 지식 수준은 평균과 표준편차를 구하여 각각 비교하였다. 분석 결과 작업 종사자의 방사선 안전 관리에 대한 지식 조사에서는 종사자 모두 높은 수준으로 평가 되었다. 결론적으로 방사선 작업종사자들의 방사선 안전관리와 관련하여 보다 다양한 요인들에 대한 연구들이 수행되어야 하며 작업종사자들의 의식을 높이기 위해서 시기적절한 교육이 필요할 것으로 사료되며, 지속적으로 방사선 작업종사자들을 관리함으로써 효율적인 방사선이용이 될 수 있는 기반이 확립될 것으로 사료된다.

• 한국조리학회지
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• 제20권4호
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• pp.37-48
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• 2014

본 연구에서는 쌀가루와 호화쌀가루의 첨가량과 처리를 달리한 요구르트를 제조하여 반응표면분석법(RSM)을 이용하여 쌀가루 첨가량의 관능적 최적점을 갖는 조성을 확인하고 이 때의 유산발효 특성을 연구하고자 하였다. RSM을 통해 발효액 조성이 최적화 된 2가지(쌀가루, 호화쌀가루)의 요구르트 발효 중 pH, 산도, 당도, 점도, 유산균 수 검사를 통하여 유산발효 특성을 알아보았다. 쌀가루와 호화쌀가루 첨가 요구르트 모두에서 발효시간이 증가함에 따라 pH가 감소하는 경향을 보였으며, 적정산도는 발효시간이 증가함에 따라 점점 증가하는 경향을 보였다. 당도는 발효시간이 증가함에 따라 감소하는 경향을 보였는데 발효되는 동안 당이 분해 감소되고 젖산발효에 의한 것으로 여겨진다. 점도는 발효 6시간에서 가장 높았으며 발효 완료 시점인 10시간에서는 발효 시작 전보다 높은 점도를 보였다. 쌀가루와 호화쌀가루 첨가 요구르트의 유산균수는 7.43~9.00 log CFU/mL으로 호상요구르트의 식품 규격 적정치 범위 이상으로 측정되어 미분첨가가 요구르트 제조 시의 유산균수에 부합하는 것을 확인할 수 있었다. 또한 쌀가루 보다는 호화쌀가루를 첨가하였을 때 쌀의 첨가량도 늘릴 수 있으며, 점도에서도 좋은 결과를 보여 호화쌀가루를 이용한 요구르트는 쌀을 활용한 더 효과적인 기능성 유산발효제품이 될 수 있을 것으로 보였다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회B
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• pp.2384-2389
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• 2007

The 2nd order response surface method (RSM) has been carried out to get optimum thermal design for enhanced heat transfer on square channel with bleed holes. The RSM was used as an optimization technique with Reynolds-averaged navier-stokes equation. Turbulence model for heat transfer analysis used RNG k-epsilon model. The wall function used enhanced wall function. Numerical local heat transfer coefficients were similar to the experimental tendency. Two design variables such as attack angle of rib (${\alpha}$), rib pitch-to-rib height ratio (p/e) were chosen. Operation condition considered bleeding ratio per bleed hole ($BR_{hole}$). A response surface were constructed by the design variables and operation condition. As a result, adjusted $R^2$ was more than 0.9. Optimization results of various objective function were similar to heat transfer in channel with and without bleed flow. But friction factor was lower than channel without bleed flow.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2001년도 제4회 압출 및 인발가공 심포지엄
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• pp.99-106
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• 2001

The design for cold extrusion dies is very important, because the die insert is subjected to very high radial and hoop stresses. The design of cold extrusion dies has many constrained conditions. In this paper, the used assumptions are such that the yield strength of each ring is selected according to the allowable tensile or compressive hoop stress in each ring and the maximum allowable inner pressure, when yielding occurs in one ring of the dies, is obtained by the proposed equation. In order to obtain design variables, such as diameter ratios and interferences, using the maximum inner pressure, the flexible tolerance method was used for shrink-fitted thick-walled cylinders. ANSYS APDL was used to perform the repeated analysis of deformation of the dies due to the variation of the design variables. The response surface methodology is utilized to analyze the relationship between the design variables and the maximum radial displacement of the die insert during extrusion. From the results, it is found that outer diameter of the die Insert has the largest effect on the minimization of maximum radial displacement at the inner surface of the dies.

• 한국수소및신에너지학회논문집
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• 제31권4호
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• pp.395-403
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• 2020

In this paper, the performance characteristics of the impeller and volute in the 2 vane pump were investigated using response surface method (RSM) with commercial computation fluid dynamics (CFD) code. Design variables were defined with the impeller blade angle and volute area distribution. The objective functions were defined as the total head, total efficiency and solid material size of the 2 vane pump. The design optimization of the design variables was determined using the RSM. The numerical results for the reference and optimum models were compared and discussed in this work.

• 전기학회논문지
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• 제59권5호
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• pp.897-903
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• 2010

This paper presents a response surface method(RSM) with Latin Hypercube Sampling strategy, which is employed to optimize a magnet pole shape of large scale BLDC motor to minimize the cogging torque. The proposed LHS algorithm consists of the multi-objective Pareto optimization and (1+1) evolution strategy. The algorithm is compared with the uniform sampling point method in view points of computing time and convergence. In order to verify the developed algorithm, a 6 MW BLDC motor is simulated with 4 design parameters (arc length and 3 variables for magnet) and 4 constraints for minimizing of the cogging torque. The optimization procedure has two stages; the fist is to optimize the arc length of the PM and the second is to optimize the magnet pole shape by using the proposed hybrid algorithm. At the 3rd iteration, an optimal point is obtained, and the cogging torque of the optimized shape is converged to about 14% of the initial one. It means that 3 iterations aregood enough to obtain the optimal design parameters in the program.

• 한국전산유체공학회지
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• 제5권2호
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• pp.55-63
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• 2000

In this paper, the numerical study has been done for the improvement of the superdetonative ram accelerator performance and for the design optimization of the system. The objective function to optimize the premixture composition is the ram tube length, required to accelerate projectile from initial velocity V/sub 0/ to target velocity V/sub e/. The premixture is composed of H₂, O₂, N₂ and the mole numbers of these species are selected as design variables. RSM(Response Surface Methodology) which is widely used for the complex optimization problems is selected as the optimization technique. In particular, to improve the non-linearity of the response and to consider the accuracy and the efficiency of the solution, design space stretching technique has been applied. Separate sub-optimization routine is introduced to determine the stretching position and clustering parameters which construct the optimum regression model. Two step optimization technique has been applied to obtain the optimal system. With the application of stretching technique, we can perform system optimization with a small number of experimental points, and construct precise regression model for highly non-linear domain. The error compared with analysis result is only 0.01% and it is demonstrated that present method can be applied to more practical design optimization problems with many design variables.

• 대한기계학회논문집B
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• 제32권4호
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• pp.300-306
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• 2008

In the present study, the second order response surface method (RSM) is carried out to get optimum thermal design for enhancing heat transfer in a square channel with bleed flow. The RSM is used as an optimization technique. To calculate the heat transfer, RNG k-epsilon model and enhanced wall function are used. To design optimum rib turbulators, two design variables such as attack angle of rib $({\alpha})$ and rib pitch-to-rib height ratio (p/e) are optimized. In these analyses, the channel inlet Reynolds number was fixed at 10,000 in both non-bleeding and bleeding cases. The response surfaces of two design variables are constructed in cases with and without bleed flow. As a result, the optimum (or highest) heat transfer values are almost the same in ranges of two cases with and without bleed flow. However, the friction losses in the case with bleed flow are lower than those without bleed flow.

• 한국기계가공학회지
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• 제5권3호
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• pp.65-70
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• 2006

The AWJM(Abrasive Water-jet Machining) technology is one of the cutting technologies, which can cut various materials with 2 or 3 times of the speed of sound. In this study, processing conditions such as jet-pressure, cutting speed, orifice diameter and stand-off distance, are used by following the design of experiments with 3 levels. Al6061 material which is normally applied on the field, is applied. Through the S/N ratio analysis with measured values, the optimization value of processing conditions to minimize the surface roughness and taper value is obtained. The order of significance is as follows; jet pressure, cutting speed, abrasive mixing ratio, orifice diameter and stand-off distance. RSM(Response Surface Method) is applied to find the optimal processing conditions to minimize both the surface roughness and the taper value by using jet pressure, cutting speed and abrasive mixing ratio.