• 한국유체기계학회 논문집
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• 제16권4호
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• pp.15-21
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• 2013

This study aims to estimate the fatigue resistance of small wind composite blade using the fatigue life estimation formula in the GL guideline. For this, firstly, we estimated a turbine blade's bending moment spectrum by using wind profile wind profile and BEMT. And fatigue tests were performed to obtain the S-N curve of composite materials used in blade. In addition, a finite element analysis was used to identify fatigue critical locations and fatigue stress spectrum. And the fatigue resistance of composite blade were evaluated using the rainflow cycle counting, and Goodman diagram and the fatigue life estimation formula in the GL guideline.

• 대한수학회지
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• 제32권4호
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• pp.725-737
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• 1995

Let $X_t = (X_t^(1), X_t^(2))', t \geqslant 0$, be a real stationary 2-dimensional Gaussian process with $EX_t^(1) = EX_t^(2) = 0$ and $$ EX_0 X'_t = (_{\rho(t) r(t)}^{r(t) \rho(t)}), $$ where $r(t) \sim $\mid$t$\mid$^-\alpha, 0 < \alpha < 1/2, \rho(t) = o(r(t)) as t \to \infty, r(0) = 1, and \rho(0) = \rho (0 \leqslant \rho < 1)$. For $t > 0, u > 0, and \upsilon > 0, let L_t (u, \upsilon)$ be the time spent by $X_s, 0 \leqslant s \leqslant t$, above the level $(u, \upsilon)$.

• Journal of Communications and Networks
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• 제6권3호
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• pp.209-215
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• 2004

In this paper, a butterfly Log-MAP decoding algorithm for turbo code is proposed. Different from the conventional turbo decoder, we derived a generalized formula to calculate the log-likelihood ratio (LLR) and drew a modified butterfly states diagram in 8-states systematic turbo coded system. By comparing the complexity of conventional implementations, the proposed algorithm can efficiently reduce both the computations and work units without bit error ratio (BER) performance degradation.

• 물과 미래
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• 제14권4호
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• pp.27-34
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• 1981

The design flow of the urban strom drainage systems has been assessed largely on a basis of empirical relations between rainfall and runoff, and the rational formula has been widely used for the cities in our country. In order to estimate it more accurately, the urban runoff simulation model based on the RRl method has been developed and applied to the sample basin in this study. The rainfall hyetograph of the design stromfor the design flow has been obtained by the determination of the total rainfall and the temporal distributions of that rainfall. The total rainfall has been assessed from the empirical formula of rainfall intensity and the temporal distribution of that rainfall determined on the basis of Huff's method from the historical rainfall data of the basin. The virtual inflow hydrograph to each inlet of the basin has been constructed by computing the series of discharges in each time increment, using design strom hyetograph and time-area diagram. The actual runoff hydrograph at the basin outlet has been computed from the virtual inflow hydrographs by developing a relations between discharge and storage for the watershed. The discharge data for verification of the simulated runoff hydrograph are not available in the sample basin and so the sensitivity analysis of the simulation model has not been possible. The peak discharge for the design of drainage systems has been estimated from the computed runoff hydrograph at the basin outlet and compared to thatl obtained form the rational formula.

• 한국시스템다이내믹스연구
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• 제14권3호
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• pp.25-49
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• 2013

As global competition for green car, that is environmentally friendly car, is getting tougher, the governments and the related industries are putting their core efforts in its diffusion. However, the green car sales are disappointing so far. To overcome the gridlock, it is necessary to develop concrete analytical framework to understand the diffusion process. Based on causal loop analysis from the previous work, we have identified main variables and relationships of them in the diffusion process and developed a stock-flow diagram and mathematical formula for the main components. The model would be applied for further quantitative simulation on the diffusion process of green car and other innovative goods as well. Also, we have suggested constructive insights for the policy makers and for the related industries. First, it is important to increase consumers' willingness to consider through marketing and word of mouth to accelerate the diffusion process. Second, in the perspective of the industry, the market share of green car should be increased at the earliest possible stage and this could be done by enhancing each components of green car attractiveness(e.g. price, driving range, social infra). Third, companies should develop a balanced investment between consumer and technology sector through a flexible financial policy. Fourth, the government continuously has the role of investing in the related R&D and social infra building. We expect the green car diffusion model and related formula from the research can provide meaningful tools to analyze the diffusion process of other new and innovative goods based on its deep researched literature review.

• 대한화장품학회지
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• 제26권1호
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• pp.93-106
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• 2000

비이온 계면활성제, 다가알코올, 물과 오일을 사용하여 단상형 액정 조성물을 제조하였고 이에 대한 물리적 성질을 조사하였다. 소수성기가 Y 형인 비이온 계면활성제인 POE octyldodecyl ether series와 친수성기가 Y 형인 POE glyceryl monostearate series가 2:1로 혼합한 계면활성제 system에 다과알코올이 혼합됨에 따른 상의 변화를 관찰하여 본 결과 7:3, 6:4, 5:5 인 비율에서 라멜라 백정상의 구조(In)가 잘 발현됨을 보여 주었으며, 상기 비율에 유성성분의 함량에 따른 라멜라 액정상의 발현을 관찰한 결과 계면활성제의 친수성이 높고, 계면활성제와 화가알코올의 비가 7:3인 system 011서 상대적으로 높은 오일을 함유한 라멜라 백정구조 형성이 가능함을 확인하였다. 전상이 되지 않은 상태로 라멜라 백정조성물의 친수성 층011 수분의 함유 정도를 관찰하여 본 결과 제조된 라멜라 액정조성물은 25 - 40% 정도의 수분을 라멜라 층간에 함유할 수 있음을 확인하였고, 백정조성물의 피부 도포 시에 우수한 피부 수분 함유 효과를 보여 주었다.

• KIEAE Journal
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• 제17권3호
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• pp.35-44
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• 2017

Purpose: This study questioned the efficiency of daylight factor as a daylight adequacy and investigated a method of how to complement its weakness by considering a direct sunlight component under a clear sky condition. Method: The Snowdon visitor centre cafe was chosen as a case study building and various techniques such as BRE formula, BRE sky protractor, Pilkington dot diagram and mock-upscale model under the artificial sky simulator were used to analyse and compare daylight factor values. An analysis of direct sunlight component under the clear sky condition was carried out by Climate Consultant 5.5, sun path diagram, and the artificial sky simulator. Result: The result of daylight factor analysis differed by the adopted techniques and it was also contradictory to the results on a direct sunlight penetration. The result not only showed the limitation of daylight factor as a metric but also suggested an improvement by combining it with direct sunlight analysis. The techniques used in this study had a merit of being applied in the early design stage and thus be beneficial to many design professions in order for early daylight performance analysis.

• 대한건축학회논문집:구조계
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• 제35권12호
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• pp.181-188
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• 2019

The maintenance of school building is pivotal issue. However, it is difficult to obtain basic analysis data for LCC(Lifecycle Cost) analysis and maintenance planning of school building. Therefore, this study proposed System Dynamics(SD) techniques to make maintenance decisions for school building. The interaction between the major parameters related to the aging of a building, maintenance activities, and cost were expressed in Causal Loop Diagram. Based on this, the formula for the relationship between causal maps was defined and converted to Stock and Flow Diagram. Through the completed SD model the 50-year plan of 214 educational building were tested by considered in account budget, maintainability, and budget allocation opinions. As a result, the integrated SD model demonstrated that it can support strategic decision making by identifying the status class and LCC behavior of school buildings by scenario. According to the scenario analysis, the rehabilitation action of preventive maintenance that primarily repairs the buildings in condition grade C showed the best performance improvement effect relative to the cost. Therefore, if the proposed SD model is expanded to consider the effects of other educational policies, the crucial performance improvement budget can be estimated in the long-term perspective.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2002년도 추계공동학술대회논문집
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• pp.139-145
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• 2002

수로에서의 선박통항으로 인해 주변환경 렌 구조물에 미치는 영향을 평가하기 위하여 선박의 추진기로 인한 흐름을 다루었다. 제한수로에서의 수치모델은 Shield's diagram과 추진기의 운동량 이론을 사용하여 개발하였다. 프로펠러에 의한 추진기방정식은 분사를 정의하는 가장 정확한 수단으로 분사계수와 분사유속을 기초로 하여 수립하였다 추진기분사에 대해 접근한 방법은 적용 선박의 출력에 기초하였으며, 추진기 분사방정식의 주요함수에는 추진력, 프로펠러 직경, 그리고 선박의 속도를 도입하였다. 또한, 수로의 수심과 선박의 홀수도 초기이동한계입경의 계산에 필요하다. 추진기로부터 분사된 유속의 분포는 Gaussian 정규분포함수로 나타내었다 저면마찰속도와 진단응력은 Sternberg 공식으로부터 유도되었으며, 아울러 선박 추진기로 인해 수로저면에서 표사이동에 현저한 영향을 미치는 경우를 사례연구를 통해서 나타내었다.

• 한국세라믹학회지
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• 제12권4호
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• pp.29-36
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• 1975

Korean clinochlore, kaolin, pyrophillite and a technical grade of alumina have been used to investigate the effects of Al2O3 on the formation and properties of cordierite bodies. The body compositions were formulated from the proper proportions of the above raw materials to cover the range of composition from the point corresponding to the stoichiometric formula of cordierite, bythe consecutive increasment of 0.2mol. Al2O3, toward the apex of Al2O3 on the MgO-Al2O3-SiO2 triaxial diagram. Each of bodies was fired with the elevated temperatures from 110$0^{\circ}C$ to 140$0^{\circ}C$ by 5$0^{\circ}C$ interval. Linear shrinkage and water absorption were taken as measures for the firing range of the bodies. The formation of cordierite was estimated from the comparative study of X-ray diffraction and dilatometry of the fired bodies. The formation of a large amount of cordierite was initiated about 120$0^{\circ}C$. The content of Al2O3 exceeded up to 0.8 mol. comparing to the stoichiometric formula of cordierite broadens the firing range of the body.