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A Study on Sales Prediction Model Based on BiLSTM-GAT Using Credit Card Transaction Data
Wonseok Jung, Dohyung Kim, Young Ik Eom
http://doi.org/10.5626/JOK.2024.51.9.807
Sales prediction using credit card transaction data is essential for understanding consumer buying patterns and market trends. However, traditional statistical and machine learning models have limitations when it comes to analyzing temporal features and the relationships between different variables, such as geographical data and sales information by service types, population, and transaction times. This paper proposes two models that can simultaneously analyze the relationships based on commercial district features and sales time-series features. To evaluate the performance of these models, we constructed graphs based on the distances and sales similarity of features between commercial districts. We then compared the performance of the proposed models with traditional time-series models, namely LSTM and BiLSTM. The results of the experiment showed that the GAT-BiLSTM model improved prediction accuracy by approximately 15% compared to the BiLSTM model, while the BiLSTM-GAT model improved it by about 29% over the BiLSTM model, as measured by RMSE.
A Software-based Secure Disaggregated Memory System on Commodity Servers
Yewon Yong, Taehoon Kim, Sungho Lee, Changdae Kim
http://doi.org/10.5626/JOK.2024.51.9.757
A disaggregated memory system is a technology that consolidates memory from multiple servers. While this technique provides large amounts of memory for applications, it also poses serious security threats due to sensitive data transmission between servers. Several studies have addressed this issue by relying on specialized hardware. However, the use of such hardware introduces not only additional costs but also challenges in adopting it on commercial servers because of compatibility issues. In this paper, we propose a software-based mechanism to ensure the security of disaggregated memory systems. Our approach aims to prevent security threats by performing encryption and integrity verification on data transmitted between servers within a disaggregated memory system. To minimize the performance overhead associated with software implementation, our approach overlaps data transmission and decryption, and encrypts only private data. In addition, we optimize the size of encryption metadata to reduce memory overhead. Through empirical evaluations, we demonstrate that our proposed software-based security mechanism incurs negligible additional performance overhead, particularly when the performance overhead from the disaggregated memory system is already minimal.
Neural Network Learning Method using Weight Mirroring and Direct Feedback Error
Soha Lee, Heesung Yang, Hyeyoung Park
http://doi.org/10.5626/JOK.2024.51.5.445
Error backpropagation algorithm is a core learning algorithm of neural networks and, until recently, has been used in various deep learning models. However, the weight update rule of error backpropagation, in which the error signal of the upper layer is sequentially transmitted to the lower layer and the weight values of the upper layer that are used to update the lower layer weights, has a problem of biological implausibility and computational inefficiency. To address these issues, learning methods using separate backward weights have been proposed, but they are still at an early stage and require further analysis and improvement from various perspectives. In this paper, we proposed a new learning method by combining the direct feedback alignment method, which directly projects the errors of the last layer into each hidden layer, and a weight mirror method with a separate step for updating backward weights. The proposed method overcomes the limitations of learning methods to implement a weight update method that is biologically plausible and allows for more efficient parallel learning. We confirmed the potential of the proposed method through experiments on various benchmark datasets.
Interactive Visual Analytics System for Criminal Intelligence Analysts with Multiple Coordinated Views
Seokweon Jung, Donghwa Shin, Jinwook Bok, Seokhyeon Park, Hyeon Jeon, Jinwook Seo, Insoo Lee, Sooyoung Park
http://doi.org/10.5626/JOK.2023.50.1.47
Data that criminal intelligence analysts have to analyze have become much larger and more complex in recent decades. However, the environment and methods of investigation have not yet kept up with those changes. In this study, we examined current investigation practices in Korean Government Agency. We focused on the sensemaking process of investigation and tried to adopt visual analytics approaches for sensemaking into the investigation. We derived tasks and design requirements and designed a multi-view visual analytics system that could satisfy them. We validated our design with a high-fidelity prototype through a case study to show realistic use cases.
A Fusion Method of Co-training and Label Propagation for Prediction of Bank Telemarketing
http://doi.org/10.5626/JOK.2017.44.7.686
Telemarketing has become the center of marketing action of the industry in the information society. Recently, machine learning has emerged in many areas, especially, financial prediction. Financial data consists of lots of unlabeled data in most parts, and therefore, it is difficult for humans to perform their labeling. In this paper, we propose a fusion method of semi-supervised learning for automatic labeling of unlabeled data to predict telemarketing. Specifically, we integrate labeling results of label propagation and co-training with a decision tree. The data with lower reliabilities are removed, and the data are extracted that have consistent label from two labeling methods. After adding them to the training set, a decision tree is learned with all of them. To confirm the usefulness of the proposed method, we conduct the experiments with a real telemarketing dataset in a Portugal bank. Accuracy of the proposed method is 83.39%, which is 1.82% higher than that of the conventional method, and precision of the proposed method is 19.37%, which is 2.67% higher than that of the conventional method. As a result, we have shown that the proposed method has a better performance as assessed by the t-test.
Water Level Forecasting based on Deep Learning : A Use Case of Trinity River-Texas-The United States
Quang-Khai Tran, Sa-kwang Song
http://doi.org/10.5626/JOK.2017.44.6.607
This paper presents an attempt to apply Deep Learning technology to solve the problem of forecasting floods in urban areas. We employ Recurrent Neural Networks (RNNs), which are suitable for analyzing time series data, to learn observed data of river water and to predict the water level. To test the model, we use water observation data of a station in the Trinity River, Texas, the U.S., with data from 2013 to 2015 for training and data in 2016 for testing. Input of the neural networks is a 16-record-length sequence of 15-minute-interval time-series data, and output is the predicted value of the water level at the next 30 minutes and 60 minutes. In the experiment, we compare three Deep Learning models including standard RNN, RNN trained with Back Propagation Through Time(RNN-BPTT), and Long Short-Term Memory (LSTM). The prediction quality of LSTM can obtain Nash Efficiency exceeding 0.98, while the standard RNN and RNN-BPTT also provide very high accuracy.
Three-Dimensional Conjugate Heat Transfer Analysis for Infrared Target Modeling
Hyunsung Jang, Namkoo Ha, Seungha Lee, Taekyu Choi, Minah Kim
The spectral radiance received by an infrared (IR) sensor is mainly influenced by the surface temperature of the target itself. Therefore, the precise temperature prediction is important for generating an IR target image. In this paper, we implement the combined three-dimensional surface temperature prediction module against target attitudes, environments and properties of a material for generating a realistic IR signal. In order to verify the calculated surface temperature, we are using the well-known IR signature analysis software, OKTAL-SE and compare the result with that. In addition, IR signal modeling is performed using the result of the surface temperature through coupling with OKTAL-SE.
A Group Modeling Strategy Considering Deviation of the User’s Preference in Group Recommendation
HyungJin Kim, Young-Duk Seo, Doo-Kwon Baik
Group recommendation analyzes the characteristics and tendency of a group rather than an individual and provides relevant information for the members of the group. Existing group recommendation methods merely consider the average and frequency of a preference. However, if the users’ preferences have large deviations, it is difficult to provide satisfactory results for all users in the group, although the average and frequency values are high. To solve these problems, we propose a method that considers not only the average of a preference but also the deviation. The proposed method provides recommendations with high average values and low deviations for the preference, so it reflects the tendency of all group members better than existing group recommendation methods. Through a comparative experiment, we prove that the proposed method has better performance than existing methods, and verify that it has high performance in groups with a large number of members as well as in small groups.
Smart Fog : Advanced Fog Server-centric Things Abstraction Framework for Multi-service IoT System
Gyeonghwan Hong, Eunsoo Park, Sihoon Choi, Dongkun Shin
Recently, several research studies on things abstraction framework have been proposed in order to implement the multi-service Internet of Things (IoT) system, where various IoT services share the thing devices. Distributed things abstraction has an IoT service duplication problem, which aggravates power consumption of mobile devices and network traffic. On the other hand, cloud server-centric things abstraction cannot cover real-time interactions due to long network delay. Fog server-centric things abstraction has limits in insufficient IoT interfaces. In this paper, we propose Smart Fog which is a fog server-centric things abstraction framework to resolve the problems of the existing things abstraction frameworks. Smart Fog consists of software modules to operate the Smart Gateway and three interfaces. Smart Fog is implemented based on IoTivity framework and OIC standard. We construct a smart home prototype on an embedded board Odroid-XU3 using Smart Fog. We evaluate the network performance and energy efficiency of Smart Fog. The experimental results indicate that the Smart Fog shows short network latency, which can perform real-time interaction. The results also show that the proposed framework has reduction in the network traffic of 74% and power consumption of 21% in mobile device, compared to distributed things abstraction.
Policy Based DDoS Attack Mitigation Methodology
Hyuk Joon Kim, Dong Hwan Lee, Dong Hwa Kim, Myung Kil Ahn, Yong Hyun Kim
Since the Denial of Service Attack against multiple targets in the Korean network in private and public sectors in 2009, Korea has spent a great amount of its budget to build strong Internet infrastructure against DDoS attacks. As a result of the investments, many major governments and corporations installed dedicated DDoS defense systems. However, even organizations equipped with the product based defense system often showed incompetency in dealing with DDoS attacks with little variations from known attack types. In contrast, by following a capacity centric DDoS detection method, defense personnel can identify various types of DDoS attacks and abnormality of the system through checking availability of service resources, regardless of the types of specific attack techniques. Thus, the defense personnel can easily derive proper response methods according to the attacks. Deviating from the existing DDoS defense framework, this research study introduces a capacity centric DDoS detection methodology and provides methods to mitigate DDoS attacks by applying the methodology.
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