• 한국건축시공학회지
• /
• 제8권5호
• /
• pp.59-65
• /
• 2008

In the evaluation method of KS on the activity factor of fly ash, same amount of cement should be replaced with fly ash. Therefore, contradictory effects on concrete strength exist, i. e. strength decease due to low content of cement and strength increase of strength due to filling-pore-function of fly ash. European Committee for Standardization (CEN) specifies the method 1 to 4. adding fly ash without reducing the content of cement, for the evaluation method on activity factor of fly ash. This study investigates the applicability of the method 2 of CEN to mix design of concrete. The followings are derived ; There is a key ratio of f)y ash mixing which enhances the incremental ratio of mixing water to improve fluidity of mortar. The incremental ratio of mixing water is maximized about 11% ratio of fly ash mixing. Compressive strength most slightly increases at that ratio of fly ash mixing. Activity factor of fly ash increases as water-cement ratio becomes low and contents of fly ash becomes high. Moreover, quality of fly ash and condition of mix design affect the applicable amount of fly ash and available range of water-cement ratio. However, this method has some problems for practical purpose because activity factors of fly ash for some cases are over 1.0. Further research should be conducted to develop more useful method of evaluating activity factor of fly ash.

• 보건교육건강증진학회지
• /
• 제4권1호
• /
• pp.65-75
• /
• 1987

This study was conducted (i) to recommend the high-scored education method as a adaptable method, and (ii) to find the most influential factor among the three acceptability components (feasibility factor, stimulation factor and reliability factor) to urban or rural residents. The accept-ability score of each health education method currently existing in urban and rural area was estimated. A total of 257 households in Guro 6-dong, Seoul, and 233 households in Jeomdong-myeon, Yeoju-gun, were sampled by interview survey using questionnaire. The four types of health education methods used in this study are; printed matter method, mailing service method. personal contact method, and group contact method. The major findings obtained from this research are as follows; 1) In urban area, the highest-scored in terms of acceptability is the personal contact method, followed by the mailing service, the printed matter, and the group contact. The mailing service method is found to be effective especially for the intelligent group people. 2) In rural area, the highest-scored in terms of acceptability is also the personal contact method, followed by the group contact, and printed matter method. In general, the group contact method is effective toward both urban-poor and rural housewives (especially in stimulation factor). To improve the health consciousness of the residents, there arises the need for the existing education program into better organized and diversified one and for educating health-educators by providing in-depth health knowledge.

• Structural Engineering and Mechanics
• /
• 제22권4호
• /
• pp.469-481
• /
• 2006

A new method called fuzzy factor method for the stationary stochastic response analysis of fuzzy truss with global fuzzy structural parameters is presented in this paper. Considering the fuzziness of the structural physical parameters and geometric dimensions simultaneously, the fuzzy correlation function matrix of structural displacement response in time domain is derived by using the fuzzy factor method and the optimization method, the fuzzy mean square values of the structural displacement and stress response in the frequency domain are then developed with the fuzzy factor method. The influences of the fuzziness of structural parameters on the fuzziness of mean square values of the displacement and stress response are inspected via an example and some important conclusions are obtained. Finally, the example is simulated by Monte-Carlo method and the results of the two methods are close, which verified the feasibility of the method given in this paper.

• 유체기계공업학회:학술대회논문집
• /
• 유체기계공업학회 2002년도 유체기계 연구개발 발표회 논문집
• /
• pp.111-115
• /
• 2002

The objective of this work is to develop improved slip factor model and correction method to predict flow through impeller in forward-curved centrifugal fan by investigating the validity of various slip factor models. Both steady and unsteady three-dimensional CFD analyses were performed with a commercial code tn validate the slip factor model and the correction method. The results show that the improved slip factor model presented in this paper could provide more accurate predictions for forward-curved centrifugal impeller than the other slip factor models since the presented model takes into account the effect of blade curvature. The comparison with CFD results also shows that the improved slip factor model coupled with the present correction method provides accurate predictions for mass-averaged absolute circumferential velocity at the exit of impeller near and above the flow rate of peaktotal pressure coefficient.

• 전기학회논문지P
• /
• 제57권3호
• /
• pp.225-230
• /
• 2008

Reactor starting method has the advantage of simplicity and closed transition in spite of lower starting torque per kVA. This method allows a smooth start with almost no observable disturbance on transition and is suitable for applications such as centrifugal pumps or fans. Reactive power doesn't contribute to work but needs to sustain the electromagnetic field required for the induction motor to operate. Starting power factor of induction motor is specially lower than running power factor. Power factor application is needed to compensate for the lower power factor of induction motor. This power factor compensation systems is occasionally being hit by the effects of the starting reactor connection position at the starting, stopping of high-voltage induction motor. This paper describes voltage and current stress affected by the installation position of power factor compensation application at the reactor starting method.

• 한국산학기술학회논문지
• /
• 제8권3호
• /
• pp.654-659
• /
• 2007

본 논문은 호텔기업이 많이 활용하고 있는 CRM의 운용성과를 측정하기 위한 측정 요인에 대한 연구를 하였다. 이를 위해 통계적인 방법인 요인분석(Factor Analysis)과 AHP(Analytic Hierarchy Process)분석 기법을 연계하여 분석하는 방법을 연구하였다. 요인분석은 서로 상관있는 변수들만을 그룹화하고, 상관도가 낮은 변수는 또 다른 그룹으로 묶는 결과를 도출한다. 그러나 요인분석은 요인의 분류 외에는 주요 정보를 제공하지 못한다. 그렇기 때문에 이를 극복하기 위해서 분산분석, 회귀분석 등 다른 통계분석 방법을 시도한다. 그러나 이러한 분석은 요인분석 결과와 연계되는 것이 아니라 독립적인 분석을 하게 되는 것이다. 그렇지만 호텔기업의 CRM 운용성과 분석에서는 요인의 중요도 분석이 중요하다. 따라서 AHP 분석기법을 연계하여 호텔기업의 CRM 운용 성과를 측정하기 위한 요인 분석방법에 대해 고찰하였다.

• Structural Engineering and Mechanics
• /
• 제23권2호
• /
• pp.195-207
• /
• 2006

An efficient and accurate algorithm is proposed to estimate cable safety factor of suspension bridges satisfying prescribed reliability levels. Uncertainties in the structure and load parameters are incorporated. The proposed algorithm integrates the concepts of the inverse reliability method and deterministic method for assessing cable safety factors of suspension bridges. The unique feature of the proposed method is that it offers a tool for cable safety assessment of suspension bridges, when the reliability level is specified as a target to be satisfied by the designer. After the accuracy and efficiency of the method are demonstrated through two numerical examples, the method is used to estimate cable safety factors of suspension bridges with span length ranging from 2000 to 5000 m. The results show that the deterministic method overestimates cable safety factor of suspension bridges because of neglecting the parameter uncertainty effects. The actual cable safety factor of suspension bridges should be estimated based on the proposed method.

• 한국안전학회지
• /
• 제35권3호
• /
• pp.49-57
• /
• 2020

In comparison with the existing static reliability analysis methods, the dynamic reliability analysis(DyRA) method is more suitable for estimating the failure probability of a structure subjected to earthquake excitations because it can take into account the frequency characteristics and damping capacity of the structure. However, the DyRA is known to have an issue of numerical stability due to the uncertainty in random sampling of the earthquake excitations. In order to solve this numerical stability issue in the DyRA approach, this study proposed two earthquake-scale factors. The first factor is defined as the ratio of the first earthquake excitation over the maximum value of the remaining excitations, and the second factor is defined as the condition number of the matrix consisting of the earthquake excitations. Then, we have performed parametric studies of two factors on numerical stability of the DyRA method. In illustrative example, it was clearly confirmed that the two factors can be used to verify the numerical stability of the proposed DyRA method. However, there exists a difference between the two factors. The first factor showed some overlapping region between the stable results and the unstable results so that it requires some additional reliability analysis to guarantee the stability of the DyRA method. On the contrary, the second factor clearly distinguished the stable and unstable results of the DyRA method without any overlapping region. Therefore, the second factor can be said to be better than the first factor as the criterion to determine whether or not the proposed DyRA method guarantees its numerical stability. In addition, the accuracy of the numerical analysis results of the proposed DyRA has been verified in comparison with those of the existing first-order reliability method(FORM), Monte Carlo simulation(MCS) method and subset simulation method(SSM). The comparative results confirmed that the proposed DyRA method can provide accurate and reliable estimation of the structural failure probability while maintaining the superior numerical efficiency over the existing methods.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2006년도 하계학술대회 논문집 Vol.7
• /
• pp.354-355
• /
• 2006

We manufactured photoelectrode of dye-sensitized solar cells (DSC) by using three methods such as squeeze method, spray method, and combination method (squeeze method first, spray method second). We examined how the morphology of an electrode's surface, the pore between particles, and condensation have an effect on an open-circuit voltage, photocurrent, fill factor, and energy conversion efficiency. Open-circuit voltage of dye-sensitized solar cells manufactured by using three methods is about 0.66V when the photoelectrode of the three DSCs is about $5{\mu}m$ thick. Photocurrent and fill factor and conversion efficiency of DSC manufactured by using squeeze method is 18.5 and 34 and 7.8, respectively. Photocurrent and fill factor and conversion efficiency of DSC manufactured by using spray method is 3.62 and 62 and 2.8, respectively. Photocurrent and fill factor and conversion efficiency of DSC manufactured by using combination method is 10.7 and 46 and 5.9, respectively. In conclusion, we find that the combination method is better than the other two methods in such respects as energy conversion efficiency and fill factor.

• 한국콘크리트학회:학술대회논문집
• /
• 한국콘크리트학회 2001년도 가을 학술발표회 논문집
• /
• pp.809-814
• /
• 2001

In this paper, dynamic properties of a bridge by traffic loads, is proposed as a reasonable method for the determining the impact factor. In addition, impact factors obtained from previous inspection reports were classified by the span length of the bridge, kind of the bridge and type of the bridge and adjusted the result of the impact factor by the statistical method and presented problems. Also, the determining method of the impact fatter using traffic load is proposed and compared the proposed method with the specification code. The method estimating the impact factor by the traffic loads can be efficiently concluded to the response of structure as reflecting the impact factor and saving the investigation cost. Also it is expected to use to maintenance of structures using the usual test of the bridge.