• 한국안전학회지
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• 제25권5호
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• pp.44-53
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• 2010

Recently, the external prestressed concrete structures are increasingly being built. The mechanical behavior of prestressed concrete beams with unbonded tendon is different from that of normal bonded PSC beams in that the increment of tendon stress was derived by whole member behavior. By this reason, the ultimate stress of external tendon is smaller than that of bonded tendon or internal unbonded tendon. However, in the domestic and abroad code, the equation of ultimate stress of external tendon is not suggested yet, and the equation of ultimate stress of internal unbonded tendon is used instead of that of external tendon. Therefore, in this paper, after effective variables of ultimate stress of external tendon were analyzed, the analytical equation of ultimate stress of external tendon was proposed. And the reasonable coefficients were proposed by statistical work of test results of 25 beam with external tendon. Finally, the practical proposed equation of ultimate stress of external tendon was proposed with analytical and statistical model. The equation of ACI-318 and AASHTO 1994 were not matched with test results and had no correlations, and the proposed equation was well matched with test results. So the proposed equation in this paper will be a effective basis for the evaluation of external tendons in analysis and design.

• Computers and Concrete
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• 제24권5호
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• pp.423-436
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• 2019

Design equations to evaluate the bursting force in a post-tensioned anchorage zone have been introduced in many design codes, and one equation in AASHTO LRFD is widely used. However, this equation may not determine the bursting force exactly because it was designed on the basis of two-dimensional numerical analyses without considering various design parameters such as the duct hole and shape of the bearing plate. To improve the design equation, modification of the AASHTO LRFD design equation was considered. The behavior of the anchorage zone was investigated using three-dimensional linear elastic finite element analysis with design parameters such as bearing plate size and diameter of sheath hole. Upon the suggestion of a modified design equation for evaluating the bursting force in an anchorage block with a rectangular anchorage plate (Kim and Kwak 2018), additional influences of design parameters that could affect the evaluation of bursting force were investigated. An improved equation was introduced for determining the bursting force in an anchorage block with a circular anchorage plate, using the same procedure introduced in the design equation for an anchorage block with a rectangular anchorage plate. The validity of the introduced design equation was confirmed by comparison with AASHTO LRFD.

• 한국축산식품학회지
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• 제38권5호
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• pp.1109-1119
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• 2018

In this paper, we report the development of a nondestructive prediction model for lean meat percentage (LMP) in Korean pig carcasses and in the major cuts using a machine vision technique. A popular vision system in the meat industry, the VCS2000 was installed in a modern Korean slaughterhouse, and the images of half carcasses were captured using three cameras from 175 selected pork carcasses (86 castrated males and 89 females). The imaged carcasses were divided into calibration (n=135) and validation (n=39) sets and a multilinear regression (MLR) analysis was utilized to develop the prediction equation from the calibration set. The efficiency of the prediction equation was then evaluated by an independent validation set. We found that the prediction equation - developed to estimate LMP in whole carcasses based on six variables - was characterized by a coefficient of determination ($R^2_v$) value of 0.77 (root-mean square error [RMSEV] of 2.12%). In addition, the predicted LMP values for the major cuts: ham, belly, and shoulder exhibited $R^2_v$ values${\geq}0.8$ (0.73 for loin parts) with low RMSEV values. However, lower accuracy ($R^2_v=0.67$) was achieved for tenderloin cuts. These results indicate that the LMP in Korean pig carcasses and major cuts can be predicted successfully using the VCS2000-based prediction equation developed here. The ultimate advantages of this technique are compatibility and speed, as the VCS2000 imaging system can be installed in any slaughterhouse with minor modifications to facilitate the on-line and real-time prediction of LMP in pig carcasses.

• 농업과학연구
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• 제38권1호
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• pp.129-143
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• 2011

In this study, to select the incoming solar radiation equation which is most suitable for the estimation of Penman evaporation, 12 incoming solar radiation equations were selected. The Penman evaporation rates were estimated using 12 selected incoming solar radiation equations, and the estimated Penman evaporation rates were compared with measured pan evaporation rates. The monthly average daily meteorological data measured from 17 meteorological stations (춘천, 강능, 서울, 인천, 수원, 서산, 청주, 대전, 추풍령, 포항, 대구, 전주, 광주, 부산, 목포, 제주, 진주) were used for this study. To evaluate the reliability of estimated evaporation rates, mean absolute bias error(MABE), root mean square error(RMSE), mean percentage error(MPE) and Nash-Sutcliffe equation were applied. The study results indicate that to estimate pan evaporation using Penman evaporation equation, incoming solar radiation equation using meteorological data such as precipitation, minimum air temperature, sunshine duration, possible duration of sunshine, and extraterrestrial radiation are most suitable for 11 study stations out of 17 study stations.

• 대한인간공학회지
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• 제20권2호
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• pp.59-70
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• 2001

White uniformity is one of the important inspection factors determining the image quality of CRT screen. In the full white pattern, white uniformity means the degree of uniform distribution of white color across the whole screen. To elicit the sensitivity factors affecting the decision of the white uniformity quality, experiments in which participants were confronted with 6 evaluation points embedded in 3 measurement groups on a CRT screen were conducted to gather the psychophysical data that are the level of white uniformity subjects perceived and CA100 produced. These data were used to develop a modified CIE1976 equation for calculating white uniformity. Performance comparison between the original CIE1976 equation and the modified equation was conducted in terms of accuracy test and magnitude estimation. It was concluded the modified equation is more sensitive in the change of white uniformity, compared to the original CIE1976 equation.

• Korean Chemical Engineering Research
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• 제62권1호
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• pp.53-69
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• 2024

The solubility of Cloxacillin sodium in ethanol, 1-propanol, isopropanol, and acetone solutions was measured at different temperatures. The melting property was also tested by using a differential scanning calorimeter (DSC). Then, the solubility data were fitted using Apelblat equation and λh equation, respectively. The Wilson model and NRTL model were not utilized to correlate the test data, since Cloxacillin sodium will decompose directly after melting. For comparison purposes, the four empirical models, i.e., Apelblat equation, λh equation, Wilson model and NRTL Model, were evaluated by using 1155 solubility curves of 103 solutes tested under different monosolvents and temperatures. The comparison results indicate that the Apelblat equation is superior to the others. Furthermore, a new method (named the calculation method) for determining the Apelblat equation using only three data points was proposed to solve the problem that there may not be enough solute in the determination of solubility. The log-logistic distribution function was used to further capture the trend of the correlation and to make better quantitative comparison between predicted data and the experimental ones for the Apelblat equation determined by different methods (fitting method or calculation method). It is found that the proposed calculation method not only greatly reduces the number of test data points, but also has satisfactory prediction accuracy.

• Computers and Concrete
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• 제9권4호
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• pp.275-291
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• 2012

The service loads are often decisive in the design of concrete structures. The evaluation of the cracking moment, $M_{cr}$, is an important issue to predict the performance of the structure, such as, the deflections of the reinforced concrete beams and slabs. To neglect the steel bars of the section is a simplification that is normally used in the computation of the cracking moment. Such simplification leads to small errors in the value of this moment (typically less than 20%). However, these small errors can conduce to significant errors when the values of deflections need to be computed from $M_{cr}$. The article shows that an error of 10% on the evaluation of $M_{cr}$ can lead to errors over 100% in the deformation values. When the deformation of the structure is the decisive design parameter, the exact computing of the cracking moment is obviously very important. Such rigorous computing might lead to important savings in the cost of the structure. With this article the authors wish to draw the attention of the technical community to this fact. A simple equation to evaluate the cracking moment, $M_{cr}$, is proposed for a rectangular cross-section. This equation leads to cracking moments higher than those obtained by neglecting the reinforcement bars and is a simple rule that can be included in Eurocode 2. To verify the accuracy of the developed model, the results of the proposed equation was compared with a rigorous computational procedure. The proposed equation corresponds to a good agreement when compared with the previous approach and, therefore, this model can be used as a practical aid for calculating an accurate value of the cracking moment.

• 대한화학회지
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• 제47권1호
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• pp.31-37
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• 2003

측정 및 화학분석에 많이 이용되는 한 점 교정식에 대하여 측정 불확도 표기 지침서(GUM)의 근사법과 Monte-Carlo Simulation에 의해 계산된 각각의 확장불확도를 비교하였다. 이 비교를 위하여 임의의 자료들을 여러 농도 수준에서 정규 분포 또는 t-분포로 가정하여 계산하였다. 나눗셈에 의한 한 점 교정식의 비선형성과 t-분포 형식을 함에 따른 입력량의 과도한 퍼짐으로 인하여, 경우에 따라서, GUM의 근사법으로 계산된 불확도가 Monte-Carlo Simulation에 의해 계산된 것보다 약 50% 이상의 오류가 있다는 것이 확인되었다. 그러나, 검출 하한을 계산하기 위하여 한 점 교정식을 이용하는 경우, 반응량의 표준불확도가 상대적으로 매우 크고 비선형성에 희한 계산 오류가 상대적으로 무시되므로 근사식에 따른 계산 오류가 발생하지 않았다.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2000년도 춘계학술대회 논문집
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• pp.43-50
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• 2000

This paper shows the recent changes of national transportation policies in some developed countries and argues that the evaluation method of the effect of transportation investment on national economy should be improved to reveal real impact of the investment. The evaluation method should develope effective performance indicators of the goals set in national transportation policy. To estimate correctly the magnitude of transportation services in national economy, the evaluation method also provides a way to measure in-house transportation services and to overcome the limits of marginal effect equal equation.

• 마케팅과학연구
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• 제13권
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• pp.209-229
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• 2004

기존의 인터넷소비자의 방문행동에 관한 연구들이 대부분 전체시장 수준에서 이루어졌고, 시장세분화를 하더라도 사전적 시장세분화로서 연구자의 주관이 반영되는 경우가 많다는 문제점이 있었다. 본 연구에서는 세분시장 수준에서의 인터넷소비자 방문행동 연구가 필요하다는 점과 함께 연구자의 임의성율 배제한 사후적 시장세분화의 필요성을 제기하고 이를 믹스처모델로 실증적으로 분석하였다. 또한 기존 연구가 웹사이트 평가요인과 방문행동 간의 단편적인 인과관계를 파악한 것과는 달리, 웹 사이트 방문행동에 영향을 미치는 요인들 간의 간접효과에 따른 통합적인 인과관계를 파악하였다. 연구에서는 실제 커뮤니티 사이트를 방문한 1,765명 의 웹상의 움직임과 설문조사를 통해 세분시장별로 이질적인 navigation pattern 과 원인변수와의 관계가 존재함을 입증하였다. 마케터는 이런 세분시장멸 이질적 관계를 이용하여 eCRM을 실행함에 있어 navigation pattern의 이질성에 영향을 미치는 변수를 세분시장별로 조절함으로써 기업이 원하는 방향으로 고객의 웹사이트 방문행위를 유도할 수 있는 기회를 얻게 되었다.