• 대한기계학회논문집B
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• 제22권1호
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• pp.70-78
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• 1998

The present study has tested semi-empirical loss models for a reliable performance prediction of mixed-flow pumps with four different specific speeds. In order to improve the predictive capabilities, this paper recommends a new internal loss model and a modified parasitic loss model. The prediction method presented here is also compared with that based on two-dimensional cascade theory. Predicted performance curves by the proposed set of loss models agree fairly well with experimental data for a variety of mixed-flow pumps in the normal operating range, but further studies considering 'droop-like' head performance characteristic due to flow reversal in mixed-flow impellers at low flow range near shut-off head are needed.

• 대한화학회지
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• 제53권5호
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• pp.491-498
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• 2009

25 ${^{\circ}C}$의 순수 물 및 n-부탄올 수용액에서 음이온성 계면활성제인 DBS (sodium dodecylbenzenesulfonate)와 비이온성 계면활성제인 Brij 30 (polyoxyethylene(4) lauryl ether)과 Brij 35 (polyoxyethylene(23)lauryl ether)의 혼합미셀화에 대한 임계미셀농도(CMC)와 반대이온의 결합상수값(B)을 DBS의 겉보기몰분율($\alpha$1)의 함수로서 전도도법으로 측정하였다. 이와 같이 측정한 CMC값에 비이상적 혼합미셀화모델을 적용함으로써 여러 가지 열역학적 함수값(Xi, $\gamma$i, Ci, aiM, $\beta$ 및 ${\Delta}H_{mix}$)들을 계산하여 상호 비교분석하였다. 그 결과, DBS는 Brij 30보다는 Brij 35와 더욱 강한 결합을 이루었으며 이상적 혼합미셀화로부터 더욱 큰 음의 벗어남을 보였다.

• 대한화학회지
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• 제56권5호
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• pp.556-562
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• 2012

$25^{\circ}C$, 4-클로로벤조산의 묽은 수용액(0.5 mM)에서 양이온성 계면활성제인 TTAB(tetradecyltrimethylammonium bromide)와 다른 종류의 계면활성제들(DTAB, CTAB, Tween-20, Tween-40 및 Tween-80)과의 혼합미셀화 현상을 분광광도법과 전도도법으로 조사하였다. 각 혼합계면활성제에서 TTAB의 겉보기몰분율(${\alpha}_1$)의 변화에 따른 임계미셀농도값(CMC)과 반대이온결합상수값(B)의 변화를 측정하여 비이상적 혼합미셀모델을 적용함으로써 여러 가지 열역학적 함수값들($X_i$, ${\gamma}_i$, $C_i$, ${\alpha}_i^M$, ${\beta}$ 및 ${\Delta}H_{mix}$)을 계산하고 비교분석하였다. 그 결과, TTAB/DTAB 혼합시스템은 이상적 혼합미셀화로 부터 큰 양의 벗어남을 보였으며, 다른 혼합시스템들은 모두 이상적 미셀모델로부터 큰 음의 벗어남을 보였다.

• 응용통계연구
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• 제23권6호
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• pp.1169-1178
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• 2010

본 논문은 불균형 자료에서 선형혼합모형에 적용되는 Akaike Information Criterion(AIC)의 효율에 대한 연구이다. Vaida와 Balanchard (2005)에 의해 제안된 cAIC(conditional AIC)는 mAIC(marginal AIC)가 임의효과의 예측에 대한 불확실성을 모형선택에서 반영하지 못하는 단점을 극복할 수 있는 방법이다. cAIC에 대한 이론적인 성질과 확장은 Liang 등 (2008)과 Greven과 Kneib (2010)에 의하여 연구되었다. cAIC의 형태는 자료의 구조에 영향을 받지는 않지만 선형혼합모형에서 모수의 추정 효율은 자료의 불균형의 정도에 따라 많은 영향을 받는 것이 알려져 있다. 기존의 연구에서 실시한 모든 모의실험이 자료가 균형인 경우에만 실행되어 자료의 불균형이 AIC에 근거한 혼합모형 선택 방법의 효율에 어떤 영향을 미치는지 알려져 있지 않다. 본 논문은 자료의 불균형이 모형선택 방법의 효율에 미치는 영향을 모의실험을 통하여 알아보았다. 자료의 불균형이 심해짐에 따라 AIC에 근거한 모형선택방법은 복잡한 모형을 선택하는 경향이 낮아짐을 보였다.

• Asian-Australasian Journal of Animal Sciences
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• 제22권1호
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• pp.57-71
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• 2009

Crop-livestock mixed farming systems depend on the efficiency with which nutrients are conserved and recycled. Home-grown forage is used as animal feed and animal excretions are applied to cultivated crop lands as manure. The objective of this study was to develop a mixed farming system model for dairy cattle in Japan. The model consisted of four sub-models: the nutrient requirement model, based on the Japanese Feeding Standards to determine requirements for energy, crude protein, dry matter intake, calcium, phosphorus and vitamin A; the optimum diet formulation model for determining the optimum diets that satisfy nutrient requirements at lowest cost, using linear programming; the herd dynamic model to calculate the numbers of cows in each reproductive cycle; and the whole farm optimization model to evaluate whole farm management from economic and environmental viewpoints and to optimize strategies for the target farm or system. To examine the model' validity, its predictions were compared against best practices for dairy farm management. Sensitivity analyses indicated that higher yielding cows lead to better economic results but higher emvironmental load in dairy cattle systems integrated with forage crop production.

• 한국수산과학회지
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• 제51권1호
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• pp.107-112
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• 2018

One-dimensional numerical model is implemented to investigate temperature variations in the mixed layer depth (MLD) with the passage of typhoons. In the model, we assume a non-divergent, infinite ocean and consider wind effects only, excluding isostatic effects (inverse barometric effects) and upwelling with vertical movement of the water column. Numerical experiments investigate the effects of typhoon tracks on temperature variations, including their dependence on vertical resolutions in the MLD and these results are compared with those in a three-dimensional primitive equation model (POM). The model reproduces features of the observed temperature variations in the MLD fairly well, and implies that wind effects, rather than isostatic effects, play a predominant role in temporal and spatial temperature variations in the MLD. After the passage of typhoons, however, the model does not reproduce well the temperature variations observed in the MLD, because a limitation of the model is its inability to reproduce events such as cyclonic eddy formation (Hong et al., 2011; Masuda and Hong, 2011). The model also shows well the so called 'rightward bias' (Price, 1981) of sea surface cooling which is the most predominant in the right hand side of typhoon's track.

• International Journal of Advanced Culture Technology
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• 제11권1호
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• pp.320-324
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• 2023

As urbanization accelerates and facilities that use energy increase, human life and property damage due to fire is increasing. Therefore, a fire monitoring system capable of quickly detecting a fire is required to reduce economic loss and human damage caused by a fire. In this study, we aim to develop an improved artificial intelligence model that can increase the accuracy of low fire alarms by mixing DeepSORT, which has strengths in object tracking, with the YOLOv5s model. In order to develop a fire detection model that is faster and more accurate than the existing artificial intelligence model, DeepSORT, a technology that complements and extends SORT as one of the most widely used frameworks for object tracking and YOLOv5s model, was selected and a mixed model was used and compared with the YOLOv5s model. As the final research result of this paper, the accuracy of YOLOv5s model was 96.3% and the number of frames per second was 30, and the YOLOv5s_DeepSORT mixed model was 0.9% higher in accuracy than YOLOv5s with an accuracy of 97.2% and number of frames per second: 30.

• 한국화재소방학회논문지
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• 제15권1호
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• pp.34-40
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• 2001

가스계 혼합소화약제의 소화성능을 검토하기 위하여 Cup-burner test장치를 설치하고 이성분계 및 삼성분계 혼합물의 불꽃소화농도를 측정하였다. 시험대상 이성분계 혼합물은 이산화탄소/HFC-23, 이산화탄소/HCFC-22, 이산화탄소/HFC-227ea, 이산화탄소/HFC-125, 이산화탄소/FIC-13I1, Hexafluoropropylene/HFC-23이고 삼성분계 흔합물은 이산화탄소/HFC-237HFC-l34a, 이산화탄소/HFC-23/HFC-227ea, 이산화탄소/HFC-23/HFC-125이다. Cup-burner test장치에서 측정된 가스계 혼합물의 소화농도는 단일성분의 소화농도와 혼합물의 구성비로 이루어진 모델에 의해 잘 예측됨을 알 수 있었다. 특히 이 모델은 혼합물의 구성성분이 물리적 소화성능을 지닐 때 잘 적용되며 화학적 소화성능의 영향이 강해질수록 측정값과의 오차가 커진다.

• Earthquakes and Structures
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• 제4권3호
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• pp.241-264
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• 2013

Since the beginning of the twentieth century, the progressive and rapid spread of reinforced concrete (RC) has led to the adoption of mixed masonry-RC solutions, such as the confined masonry. However, together with structures conceived with a definite role for earthquake behaviour, the spreading of RC technology has caused the birth of mixed solutions inspired more by functional aspects than by structural ones, such as: internal masonry walls replaced by RC frames, RC walls inserted to build staircases or raising made from RC frames. Usually, since these interventions rise from a spontaneous build-up, any capacity design or ductility concepts are neglected being designed only to bear vertical loads: thus, the vulnerability assessment of this class becomes crucial. To investigate the non-linear seismic response of these structures, suitable models and effective numerical tools are needed. Among the various modelling approaches proposed in the literature and codes, the authors focus their attention on the equivalent frame model. After a brief description of the adopted model and its numerical validation, the authors aim to point out some specific peculiarities of the seismic response of mixed masonry-RC structures and their repercussions on safety verification procedures (referring in particular way to the non-linear static ones). In particular, the results of non-linear static analyses performed parametrically to various configurations representative of different interventions are discussed.

• Structural Engineering and Mechanics
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• 제81권3호
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• pp.379-394
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• 2022

Shallow footings usually belonged to the category of thick plate structures. For accurate analysis of thick plates, the contribution of out-of-plane components of the stress tensor should be considered in the formulation. Most of the available shallow footing models are based on the classical plate theories, which usually neglect the effects of the out-of-plane stresses. In this study, a mixed-field plate finite element model (FEM) is developed for the analysis of shallow footings rested on soil foundations. In addition to displacement field variables, the out-of-plane components of the stress tensor are also assumed as a priori unknown variables. For modeling the interaction effect of the soil under and outside of the shallow footings, the modified Vlasov theory is used. The tensionless nature of the supporting soil foundation is taken into account by adopting an incremental, iterative procedure. The equality requirement of displacements at the interface between the shallow footing and soil is fulfilled using the penalty approach. For validation of the present mixed FEM, the obtained results are compared with the results of 3D FEM and previous results published in the literature. The comparisons show the present mixed FEM is an efficient and accurate tool for solving the problems of shallow footings rested on subsoil.