Discrete stochastic EOQ model for deteriorating inventory in supply chain using Hamilton-Jacobi-Bellman equation

Long Le Ngoc Bao,Sam-Sang You,Hwan-Seong Kim 한국마린엔지니어링학회 2024 한국마린엔지니어링학회지 Vol.48 No.1

Intelligent Decision Support Algorithm for Uncertain Inventory Management

Le Ngoc Bao Long,Sam-Sang You,Truong Ngoc Cuong,Hwan-Seong Kim 한국항해항만학회 2023 한국항해항만학회 학술대회논문집 Vol.2023 No.1

This paper discovers a robust managerial strategy for a stochastic inventory of perishable products, where the model experiences changing factors including inner parameters and an external disturbance with unknown form. An analytical solution for the optimization problem can be obtained by applying the Hamilton-Bellman-Jacobi equation, however the policy result cannot completely suppress the oscillation from the external disturbance. Therefore, an intelligent approach named Radial Basis Function Neural Networks is applied to estimate the unknown disturbance and provide a robust controller to manipulate the inventory level more effective. The final results show the outstanding performance of RBFNN controller, where both the estimation error and control error are guaranteed in the predefined limit.

Design and Simulation of a Monorail Network for the Inter-terminal Transport

Ngoc Cuong Truong,김환성,김인용,DuyAnh Nguyen,Long Le Ngoc Bao 한국항해항만학회 2020 한국항해항만학회지 Vol.44 No.5

In line with the trend of global transport volume which has increased rapidly over the years, internal transportation in seaports is always conducted with high frequency. Thus, there is always much potential for traffic jams as well as high transportation costs and emissions. Many efforts have been initiated to streamline the inter-terminal container transport (ITT) through the development of automated vehicles and equipment as well as using private transport facilities to overcome these limitations. The purpose of this paper to develop a framework to design, analyze, and validate the efficiency of a new ITT system in a port area based on the monorail network and automatic vehicles. First, the number of shuttles and loaders was determined depending on the transport demand scenario. Next, a simulation model was applied to evaluate the system performance as well as gain more insight into the working process of the ITT system. Finally, by setting goals for the performance indicators, the results showed that the system was highly efficient with 100% of the containers delivered to their destination on time. Besides, a series of other performance tracking was provided to provide insight into the system's capabilities.

Exposure to Tobacco Advertising and Promotion among School Children Aged 13-15 in Vietnam - an Overview from GYTS 2014

Tran, Khanh Long,Phung, Xuan Son,Kim, Bao Giang,Phan, Thi Hai,Doan, Thi Thu Huyen,Luong, Ngoc Khue,Pham, Thi Quynh Nga,Nguyen, Tuan Lam,Hoang, Van Minh,Le, Thi Thanh Huong Asian Pacific Journal of Cancer Prevention 2016 Asian Pacific journal of cancer prevention Vol.17 No.no.sup1

Evidence shows that tobacco advertising and promotion activities may increase tobacco consumption and usage, especially in youth. Despite the regulation on prohibiting advertisement of any tobacco product, tobacco advertisement and promotion activities are still common in Vietnam. This article presents current exposure to tobacco advertising and promotion (TAP) among school children aged 13 to 15 years in Vietnam in 2014 and potential influencing factors. Data from the Global Youth Tobacco Survey 2014 in Vietnam covering 3,430 school aged children were used. Both descriptive and analytical statistics were carried out with Stata 13 statistical software. Binary logistic regression was applied to explain the exposure to TAP among youth and examine relationships with individual factors. A significance level of p<0.05 and sampling weights were used in all of the computations. In the past 30 days, 48.6% of the students experienced exposure to at least 1 type of tobacco advertising or promotion. Wearing or otherwise using products related to tobacco was the most exposure TAP type reported by students (22.3%). The internet (22.1), points of sales (19.2) and social events (11.5) were three places that students aged 13-15 frequently were exposed to TAP. Binary logistic results showed that gender (female vs male) (OR = 0.61, 95%CI: 0.52 - 0.71), susceptibility to smoking (OR = 2.12, 95%CI: 1.53 - 2.92), closest friends' smoked (OR = 1.43, 95%CI: 1.2 - 1.7) and parents smoking status (OR = 2.83, 95%CI: 1.6 - 5.01) were significantly associated with TAP exposure among school-aged children. The research findings should contribute to effective implementation of measures for preventing and controlling tobacco use among students aged 13-15 in Viet Nam.

Factors Affecting Training Quality and Student Satisfaction: An Empirical Study in Vietnam

Duong Thi Hai LE,Long Duc Bao NGUYEN,Chau Le Ngoc PHAN,Tuan Minh VU,Hien Thu PHAN 한국유통과학회 2022 The Journal of Asian Finance, Economics and Busine Vol.9 No.4

The purpose of this study was to determine the factors that influence the training quality of Van Lang University’s Finance Banking faculty (VLU). Another goal was to discover a way to increase training quality and give students the greatest experience possible. To achieve the following goals, qualitative research was used in combination with questionnaires and document reviews. A total of 700 surveys were sent out, with 624 responses. In-depth interviews with 12 graduates were conducted during the qualitative stage to obtain their perspectives on their time at VLU. The impact of five factors (instructor qualification, facility, education program, accessibility, and student interaction) was investigated in this study, and the findings revealed that all of them significantly mediated the relationship with the training quality of VLU’s Finance Banking faculty. The findings show that it is vital to improve the training quality to increase student satisfaction and boost their academic abilities. With the framework from this study, policymakers, researchers, and institutes can cooperate in developing and upgrading the general training quality at higher education institutions in Vietnam. Improving the training quality of a faculty will continue to be a challenge. Therefore, this is a topic that requires continuous research.

[ICACE2022] Prediction of container throughout of Qingdao port using optimized echo state network and improved particle swarm optimization

Zitong Qu,Cuong Truong Ngoc,Bao Long Le Ngoc,이승필,김환성 한국마린엔지니어링학회 2023 한국마린엔지니어링학회지 Vol.47 No.1

The container throughput in a container logistics system is an important technical index, irrespective of the method used to manage and forecast the port throughput. The Qingdao port, one of the most important ports in North China, has the advantage of being located in the "One belt One Road" position. At present, the forecasting method for the container transportation throughput of Qingdao port still needs to be optimized, and a model that can predict its development trend needs to be constructed. Echo state networks (ESN) have been widely used in time-series prediction owing to their simple structure and fast convergence speed. To solve the problem of the applicability of the random weight matrix generated in the ESN to a specific time series, this study proposes an improved particle swarm optimization (PSO) algorithm to optimize partial random weights in the ESN. Compared to the standard particle swarm optimization algorithm, the inertia weight and learning factor were adjusted to improve the optimization performance of the algorithm. Furthermore, by comparing the historical data with the predicted values, the prediction accuracy of the model was found to be over 98%. The container throughput of Qingdao port from 2022 to 2024 was predicted, which showed that the container throughput of Qingdao Port will maintain a rapid and stable growth trend.

Distributed Interference Management in Two-Tier CDMA Femtocell Networks

Duy Trong Ngo,Long Bao Le,Le-Ngoc, T.,Hossain, E.,Dong In Kim IEEE 2012 IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS Vol.11 No.3

<P>This paper proposes distributed joint power and admission control algorithms for the management of interference in two-tier femtocell networks, where the newly-deployed femtocell users (FUEs) share the same frequency band with the existing macrocell users (MUEs) using code-division multiple access (CDMA). As the owner of the licensed radio spectrum, the MUEs possess strictly higher access priority over the FUEs; thus, their quality-of-service (QoS) performance, expressed in terms of the prescribed minimum signal-to-interference-plus-noise ratio (SINR), must be maintained at all times. For the lower-tier FUEs, we explicitly consider two different design objectives, namely, throughput-power tradeoff optimization and soft QoS provisioning. With an effective dynamic pricing scheme combined with admission control to indirectly manage the cross-tier interference, the proposed schemes lend themselves to distributed algorithms that mainly require local information to offer maximized net utility of individual users. The approach employed in this work is particularly attractive, especially in view of practical implementation under the limited backhaul network capacity available for femtocells. It is shown that the proposed algorithms robustly support all the prioritized MUEs with guaranteed QoS requirements whenever feasible, while allowing the FUEs to optimally exploit the remaining network capacity. The convergence of the developed solutions is rigorously analyzed, and extensive numerical results are presented to illustrate their potential advantages.</P>

Robust Lane Detection Algorithm for Autonomous Trucks in Container Terminal

Ngo Quang Vinh,Sam-Sang You,Le Ngoc Bao Long,Hwan-Seong Kim 한국항해항만학회 2023 한국항해항만학회 학술대회논문집 Vol.2023 No.1

Container terminal automation might offer many potential benefits, such as increased productivity, reduced cost, and improved safety. Autonomous trucks can lead to more efficient container transport. A robust lane detection method is proposed using score-based generative modeling through stochastic differential equations for image-to-image translation. Image processing techniques are combined with Density-Based Spatial Clustering of Applications with Noise (DBSCAN) and Genetic Algorithm (GA) to ensure lane positioning robustness. The proposed method is validated by a dataset collected from the port terminals under different environmental conditions and tested the robustness of the lane detection method with stochastic noise.