• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회B
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• pp.2280-2285
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• 2008

A general flow distribution model and a simple process of numerical analysis, which can be applied to multi-pass systems with manifolds, are presented. Correlations are derived from the discrete model, and numerically calculated using a modified equal pressure method. The predicted pressure distribution agrees well with the available experimental results of other researchers with the average error less than 2% for 10 branch manifolds, and 4% for 20 branch manifolds. A parametric study is performed to demonstrate the effect on the flow distribution.

• Journal of applied mathematics & informatics
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• 제41권6호
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• pp.1275-1301
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• 2023

This paper introduced the Weibull Marshall-Olkin Power Lomax (WMOPL) distribution. The statistical aspects of the proposed model are presented, such as the quantiles function, moments, mean residual life and mean deviations, variance, skewness, kurtosis, and reliability measures like the residual life function, and stress-strength reliability. The parameters of the new model are estimated using six different methods, and simulation research is illustrated to compare the six estimation methods. In the end, two real data sets show that the Weibull Marshall-Olkin Power Lomax distribution is flexible and suitable for modeling data.

• 한국농림기상학회지
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• 제26권1호
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• pp.31-52
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• 2024

나무의 가지 구조와 생리학 사이의 중요한 관계를 고려할 때 가지 구조를 이해하는 것은 수종의 분류나 3D 나무 모델링과 같은 분야에 중요하다. 지상형 라이다는 나무의 구조를 자세히 포착하고 정량적 구조 모델은 지상형 라이다로부터 얻어진 포인트 클라우드에서 가지의 반경과 길이의 계산을 가능하게 한다. 선행 연구에서는 반경 비율이나 길이 비율 등 가지의 구조를 나타내는 인자의 대푯값으로 평균 또는 중앙값에 의존하거나 줄기와 1분기 가지의 관계만을 다루었다. 본 연구는 가시칠엽수, 은행나무, 왕벚나무에서 부모와 자식 가지 사이의 반경 비율, 길이 비율 및 분지각 세 가지 인자에 대해 3분기 가지까지 인자들의 추정 분포를 살펴보고 추정 분포들을 분기별, 종별로 비교하는 것을 목표로 한다. 인자들에 적합한 분포를 알아보기 위해 인자들을 여러 확률 분포로 추정해 보았고, 평균 Kolmogorov-Smirnov 통계량에 의거해 각각 그 수치가 반경의 경우 0.048, 길이의 경우 0.061, 각도의 경우 0.050으로 감마 분포가 최적의 분포로 선택되었다. 추정된 분포 내에서 최빈값과 평균값, 최빈값과 중앙값 사이의 차이를 정규화 한 평균은 반경에 경우 11.2% 및 7.5%, 길이에 경우 17.0% 및 11.5%, 분지각의 경우 8.2% 및 5.5%로 상당한 차이를 보였다. 추정된 분포 사이에서 분기별, 종별 비교 분석을 수행했으며, 그 결과 인자들로부터 추정된 분포는 분기와 종에 따라 다양한 분포 양상을 보였다. 본 연구는 이러한 인자들의 확률 분포를 조사하는 것이 가지 구조에 대해 더 상세한 묘사를 제공할 수 있음 시사한다. 또한 가지 구조의 포괄적인 이해를 위해 더 높은 분기의 가지를 조사하는 것의 중요성을 강조한다.

• Ocean and Polar Research
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• 제34권1호
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• pp.37-51
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• 2012

We investigated the distribution and species composition of zooplankton in relation to hydrographical characteristics in the Korea Strait during the winter (February) and summer (July) of 2009. Satellite images of sea surface temperatures and in situ CTD data showed that the southeastern water zone (St3-5) off Jeju Island was strongly influenced by the Tsushima Current during both the winter and summer, whereas the Changjiang Diluted Water, characterized as water with relatively low salinity, was evident in the coastal waters of Jeju Island during the summer. During winter, zooplankton abundance was significantly higher than in the summer, with dominance by copepods, ostracods, siphonophorans, appendicularians, and nauplii. In both seasons, copepods represented >70% of the total zooplankton population. Calanus sinicus, a large calanoid copepod, was dominant in near the coast, and that may be associated with the intrusion of low salinity water (i.e., the Changjiang Diluted Water) along the coast. The abundance of P. parvus s.l. and A. omorii, known as neritic copepods, was mainly associated with the Korea Southern Coastal Water. Foraminiferans, Ostracods, O. plumifera, and P. aculeatus were concentrated in the southeastern water off Jeju Island during both seasons; showing their association with the Tsushima Current, which is characterized warm, high salinity water. Our results suggest that the distribution, abundance, and species composition of zooplankton are highly influenced by different water masses in the Korea Strait.

• Advances in concrete construction
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• 제9권1호
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• pp.103-113
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• 2020

This paper deal with the critical fluid velocity response of nanocomposite pipe conveying fluid based on numerical method. The pressure of fluid is obtained based on perturbation method. The motion equations are derived based on classical shell theory, energy method and Hamilton's principle. The shell is reinforced by nanoparticles and the distribution of them are functionally graded (FG). The mixture rule is applied for obtaining the equivalent material properties of the structure. Differential quadrature method (DQM) is utilized for solution of the motion equations in order to obtain the critical fluid velocity. The effects of different parameters such asCNT nanoparticles volume percent, boundary conditions, thickness to radius ratios, length to radius ratios and internal fluid are presented on the critical fluid velocity response structure. The results show that with increasing the CNT nanoparticles, the critical fluid velocity is increased. In addition, FGX distribution of nanoparticles is the best choice for reinforcement.

• Advances in Computational Design
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• 제2권2호
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• pp.133-146
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• 2017

This study aimed to investigate the effect of initial member length an imperfection in the load carrying capacity of double-layer domes space structures. First, for the member length imperfection of each member, a random number is generated from a normal distribution. Thereupon, the amount of the imperfection randomly varies from one member to another. Afterwards, based on the Push Down analysis, the collapse behavior and the ultimate capacity of the considered structure is determined using nonlinear analysis performed by the OpenSees software and this procedure is repeated numerous times by Monte Carlo simulation method. Finally, the reliability of structures is determined. The results show that the collapse behavior of double-layer domes space structures is highly sensitive to the random distribution of initial imperfections.

• 한국산업경영시스템학회:학술대회논문집
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• 한국산업경영시스템학회 2002년도 춘계학술대회
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• pp.349-357
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• 2002

This research is basically deals with an inventory distribution system with several regional sales branches. Under the continuous review policy, each sales branch places an order to its supplier whenever on hand plus on order inventory falls on the order point, and the order quantity is received after elapsing a certain lead time. This research first shows the method how to apply the product with low lever of demand into the continuous review policy. For the application, we use an order level as the maximum level of inventory during an order cycle. Also we analyze the lost sales case as a customer behavior. Further we use variable demands and variable lead times for more realistic situation. Based on the above circumstances, the research mainly discusses those methods to decide the optimal order level, order point, and order quantity for each sales branch which guarantees the system wide goal level of service, while keeping the minimum level of the system wide total inventory.

• 유통과학연구
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• 제11권6호
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• pp.13-19
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• 2013

Purpose - This study aims to predict the audit reports of listed companies on the Tehran Stock Exchange by using meta-heuristic algorithms. Research design, data, methodology - This applied research aims to predict auditors reports' using meta-heuristic methods (i.e., neural networks, the ANFIS, and a genetic algorithm). The sample includes all firms listed on the Tehran Stock Exchange. The research covers the seven years between 2005 and 2011. Results - The results show that the ANFIS model using fuzzy clustering and a least-squares back propagation algorithm has the best performance among the tested models, with an error rate of 4% for incorrect predictions and 96% for correct predictions. Conclusion - A decision tree was used with ten independent variables and one dependent variable the less important variables were removed, leaving only those variables with the greatest effect on auditor opinion (i.e., net-profit-to-sales ratio, current ratio, quick ratio, inventory turnover, collection period, and debt coverage ratio).

• 대한기계학회논문집B
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• 제30권8호
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• pp.741-748
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• 2006

This paper numerically investigates the effects of pass arrangement on the flow distribution characteristics and the performance of a multi-pass multi-branch heat exchanger. Four cases of pass arrangement (2, 4, 6, 8 pass) are chosen to select a proper pass arrangement. A JF factor is used as an evaluation characteristic value to consider the heat transfer and the pressure drop. The present results indicate that 4-pass heat exchanger shows the best performance, and the design parameters in 4-pass heat exchanger are optimized. The design parameters are the locations of the inlet, outlet and separator, and are optimized using a response surface methodology. The JF factor of the optimum model is increased by about 9.3%, compared to that of the reference model (2-pass heat exchanger).

• 산업경영시스템학회지
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• 제25권3호
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• pp.78-84
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• 2002

This research is basically deals with an inventory distribution system with several regional sides branches. Under the continuous review policy, each sales branch places an order to its supplier whenever on hand plus on order inventory falls on the order point, and the order quantity is received after elapsing a certain lead time. This research first shows the method how to apply the product with low lever of demand into the continuous review policy. For the application, we use an order level as the maximum level of inventory during an order cycle. Also we analyze the lost sales case as a customer behavior. Further we use variable demands and variable lead times for more realistic situation. Based on the above circumstances, the research mainly discusses those methods to decide the optimal order level, order point, and order quantity for each sales branch which guarantees the system wide goal level of service, while keeping the minimum level of the system wide total inventory.