• 한국추진공학회:학술대회논문집
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• 한국추진공학회 1993년도 제1회 학술강연회논문집
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• pp.55-61
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• 1993

An experimental investigation was conducted in order to determine the flammability limit of the solid fuel ramjet using the backward facing step flow combustion of the plexiglass grain. In order to get the different step height ratio, the grain was drilled straight forward or stepwise. The Phoenics computer code was adopted in order to compare. the flow patterns of the some sample tests using a non-reacting cold turbulent flow model. The stepwise grain give some loading advantage; specially thin and long shape grain design.

• 동력기계공학회지
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• 제9권4호
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• pp.187-193
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• 2005

In this paper, we proposes a man-machine interface design for fault diagnosis system with inter-node search method in a Petri net model. First, complicated fault cases are modeled as the Petri net graph expressions. Next, to find out causes of the faults on which we focus, a Petri net model is analyzed using the backward reasoning of transition-invariance in the Petri net. In this step, the inter-node search method algorithm is applied to the Petri net model for reducing the range of sources in faults. Finally, the proposed method is applied to a fault diagnosis of a refrigeration system to confirm the validity of the proposed method.

• 소성∙가공
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• 제12권3호
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• pp.251-258
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• 2003

The paper deals with an analysis of an extrusion process with a divided material flow in a combined radial - backward extrusion. The paper discusses the influences of tool geometry such as punch nose angle, relative gap height, die comer radius on material flow and surface expansion into can and flange region. To analyze the process, numerical simulations by the FEM and experiment, an Al alloy as a model material have been performed. Based on the results, the influence of design parameters on the distribution of divided material flow and surface expansion are obtained.

• 한국가정과교육학회지
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• 제30권3호
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• pp.175-193
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• 2018

본 연구는 가정과 수업에서 학습자의 영속적 이해를 돕기 위하여 2015 개정 중학교 가정교과 '식생활' 단원을 Wiggins와 McTighe가 제시한 백워드 설계 모형을 활용하여 교수·학습 과정안을 설계하는 데 목적이 있다. 이를 위하여 2015 개정 교육과정의 성취기준과 내용 요소를 분석하고, 중학교 '식생활' 단원을 1차시부터 8차시에 해당하는 교수·학습 과정안을 개발하였다. 그 결과 첫째, 2015 개정 중학교 가정교과 '식생활 단원'의 성취기준에서는 '청소년기 영양의 중요성', '청소년기 식생활 문제', '식행동 평가'를 통하여 식생활 관리 방안이 강조되었다. 학습요소는 '균형잡힌 식사', '청소년기 영양', '식사의 계획과 선택'이었고, 영양소 판단능력과 균형잡힌 식생활 능력으로 교과역량을 설정하였다. 식생활 단원의 12종 교과서 내용을 분석한 결과 대부분의 교과서에서 핵심 개념들을 중심으로 다루고 있었지만 '청소년기 영양'과 '식생활', '식행동'에 대한 영속적 이해를 도모하는 내용이나 활동이 부족한 것으로 나타났다. 둘째, 교수·학습 과정안의 개발은 백워드 설계 모형의 3단계 절차에 따라 개발되었으며 자가 점검과 전문가 검토를 거쳐 최종 8차시의 템플릿을 완성하였다. 이는 2015 개정 교육과정의 의도를 구현한 수업 방식을 위해 학교 현장에서 가정과 교사가 수업에 활용하고 적용하여 수업 설계에 도움을 줄 수 있을 것으로 생각된다.

• 한국항공우주학회지
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• 제40권10호
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• pp.840-845
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• 2012

본 논문에서는 후향계단(Backward Facing Step) 유동장의 유동운동에 대한 ARX(Auto Regressive eXogenous) 모델링 기법을 제시한다. BFS 유동장 모델링을 위해 밀도를 모드분석을 통해 고유 공간모드와 시간계수를 추출한다. 입력 차수와 상태변수 차수는 각각 유동장 스팩트럼 분석과 시간계수 분석을 통해 결정한다. 또한, 유동장의 속도 분석을 통해 ARX의 입력 지연 차수를 결정한다. 한편, ARX 모델의 계수는 신경망을 이용하여 설계한다.

• Design & Manufacturing
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• 제6권2호
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• pp.42-47
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• 2012

The paper deals with an analysis of an extrusion process with a divided material flow in a combined radial - backward extrusion. We have discussed the influences of tool geometry such as punch nose angle, relative gap height, die corner radius on material flow and surface expansion into can and flange region. To analyse the process, numerical simulations by the FEM and experiment by physical modeling using Al alloy as a model material have been performed. Based on the results, the influence of fixed parameters on the distribution of divided material flow and surface expansion are obtained.

• 한국멀티미디어학회논문지
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• 제9권12호
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• pp.1607-1616
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• 2006

The growing market of multimedia and digital signal processing requires significant data-path portions of SoCs. However, the common models for verification are not suitable for SoCs. A novel model--WGL (Weighted Generalized List) is proposed, which is based on the general-list decomposition of polynomials, with three different weights and manipulation rules introduced to effect node sharing and the canonicity. Timing parameters and operations on them are also considered. Examples show the word-level WGL is the only model to linearly represent the common word-level functions and the bit-level WGL is especially suitable for arithmetic intensive circuits. The model is proved to be a uniform and efficient model for both bit-level and word-level functions. Then Based on the WGL model, a backward-construction logic-verification approach is presented, which reduces time and space complexity for multipliers to polynomial complexity(time complexity is less than $O(n^{3.6})$ and space complexity is less than $O(n^{1.5})$) without hierarchical partitioning. Finally, a construction methodology of word-level polynomials is also presented in order to implement complex high-level verification, which combines order computation and coefficient solving, and adopts an efficient backward approach. The construction complexity is much less than the existing ones, e.g. the construction time for multipliers grows at the power of less than 1.6 in the size of the input word without increasing the maximal space required. The WGL model and the verification methods based on WGL show their theoretical and applicable significance in SoC design.

• Journal of Mechanical Science and Technology
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• 제19권3호
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• pp.743-755
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• 2005

Human Sensibility Engineering System (HSES) has been applied to product development for customer's satisfaction based on ergonomic technology. The system is composed of three parts such as human sensibility analysis, inference mechanism, and presentation technologies. Inference mechanism translating human sensibility into design elements plays an important role in the HSES. In this paper, we propose a rule-based inference model for HSES. The rule-based inference model is composed of five rules and two inference approaches. Each of these rules reasons the design elements for selected human sensibility words with the decision variables from regression analysis in terms of forward inference. These results are evaluated by means of backward inference. By comparing the evaluation results, the inference model decides on product design elements which are closer to the customer's feeling and emotion. Finally, simulation results are tested statistically in order to ascertain the validity of the model.

• 과학교육연구지
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• 제41권1호
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• pp.80-97
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• 2017

본 연구의 목적은 초등학교 과학의 생물과 환경 단원에서 백워드 디자인의 적용 효과를 알아보는 데 있다. 백워드 디자인은 학습의 결과를 먼저 명료화한 후, 이것을 토대로 수업 방법과 교수 요목을 결정하는 것이다. 이 방법은 교육 내용-평가-학습 활동 사이의 일관성을 유지할 수 있고 학생들의 진정한 이해를 도울 수 있는 장점이 있다. 본 연구 대상은 초등학교 6학년 78명이며, 이 모델 적용에 따른 효과를 알아보기 위해 학생들이 수행한 프로젝트 자료, 과학 학습 정서 검사, 학업 성취도 검사 자료가 수집되었다. 수집된 자료는 SPSS 23 통계 패키지로 t-test와 ANCOVA 검증이 이루어졌다. 연구의 결론은 다음과 같다. 첫째, 백워드 디자인을 적용한 실험 집단에서 학생들이 2가지 프로젝트를 수행한 결과물을 분석한 결과 과학의 내용에 대해서는 비교적 정확하게 이해하고 있었으나 창의적인 산출물을 만들어내지는 못함을 알 수 있었다. 둘째, 백워드 디자인에 따라 수업을 하여도 과학 학습정서 부문의 성취가 유의미하게 향상되지는 않음을 알 수 있었다. 셋째, 백워드 디자인에 의해 학생들의 학업 성취도는 유의미한 향상을 보였다.

• 유통과학연구
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• 제14권2호
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• pp.41-45
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• 2016

Purpose - Finding an optimal path is an essential component for the design and operation of smart transportation or logistics network. Many applications in navigation system assume that travel time of each link is fixed and same. However, in practice, the travel time of each link changes over time. In this paper, we introduce a new transportation problem to find a latest departing time and delivery path between the two nodes, while not violating the appointed time at the destination node. Research design, data, and methodology - To solve the problem, we suggest a mathematical model based on network optimization theory and a backward search method to find an optimal solution. Results - First, we introduce a dynamic transportation problem which is different with traditional shortest path or minimum cost path. Second, we propose an algorithm solution based on backward search to solve the problem in a large-sized network. Conclusions - We proposed a new transportation problem which is different with traditional shortest path or minimum cost path. We analyzed the problem under the conditions that travel time is changing, and proposed an algorithm to solve them. Extending our models for visiting two or more destinations is one of the further research topics.