Yoppy Sazaki

Verified email at gmail.com

Faculty of Computer Science
Universitas Sriwijaya




My research interests and experiences cover a variety of topics, ranging from game theory to multimedia and machine learning. These include (1) game theory for education, (2) serious games and gamification, (3) use of multimedia (e-learning) for education, (4) data analysis and processing.


Scopus Publications

Scopus Publications

  • A LSTM-Method for Bitcoin Price Prediction: A Case Study Yahoo Finance Stock Market
    Ferdiansyah Ferdiansyah, Siti Hajar Othman, Raja Zahilah Raja Md Radzi, Deris Stiawan, Yoppy Sazaki, and Usman Ependi

    ICECOS 2019 - 3rd International Conference on Electrical Engineering and Computer Science, Proceeding, Pages: 206-210, Published: October 2019 IEEE
    Bitcoin is a kind of Cryptocurrency and now is one of type of investment on the stock market. Stock markets are influenced by many risks of factor. And bitcoin is one kind of cryptocurrency that keep rising in recent few years, and sometimes sudden fall without knowing influence behind it on the stock market. Because it’s fluctuations, there’s a need and automation tool to predict bitcoin on the stock market. This research study learns how to create model prediction bitcoin stock market prediction using LSTM, LSTM (Long Short Term Memory) is another type of module provided for RNN later developed and popularized by many researchers, like RNN, the LSTM also consists of modules with recurrent consistency. The Method that we apply on this research, also technique and tools to predict Bitcoin on stock market yahoo finance can predict the result above $ 12600 USD for next days after prediction, in the last section we make conclusions and discuss future works.

  • Game Refinement Settings on Idle Games
    Yoppy Sazaki, Anggina Primanita, Siti Zaiton Mohd Hashim, and Indri Dwi Ayu

    Proceeding of 2019 5th International Conference on Wireless and Telematics, ICWT 2019, Published: July 2019 IEEE
    Idle game is a game that has minimal interaction with the player so it is considered unpleasant. To make the idle game more entertaining it can be done by applying a comfortable setting. The comfortable setting can be analyzed through measure excitement of game using game refinement. Game with game refinement value within zone value 0,07–0,08 is considered as an ideal and fun to played. Testing is done by determining the parameters first by analyzing idle RPG Infinity Heroes. After getting the parameters, testing is done by applying 4 different settings where every setting will be played 50 times. The result showed that game refinement value on the dynamic setting is within zone value 0,08 which indicates this setting is suitable to be applied on idle RPG game that has same environment with Infinity Heroes

  • Development of "child friendly ICT" textbooks to improve professional competence of teacher candidates: A case study of early childhood education program students
    Sri Sumarni, Rahmi Ramadhani, Yoppy Sazaki, Ruri Tria Astika, Windi Dwi Andika, and Andika Eko Prasetiyo

    Journal for the Education of Gifted Young Scientists, eISSN: 2149360X, Pages: 643-658, Published: 2019 Journal for Educating Gifted Young Scientists (JEGYS)
    The purpose of this study is to develop textbooks on child-friendly of Information, Com m unication , & Technology (ICT) that are valid, practical and effective in improving the professional competence of teacher education students (PG) PAUD Sriwijaya University. This study uses the Research and Development model with the type of Analysis, Design, Development, Implementation, and Evaluation (ADDIE) which consists of five stages, namely analysis, design, develop, implementation, and evaluation. The sample in this study was Sriwijaya University PAUD teacher education study program students. In the implementation phase, field trials were carried out as a result of the development of child-friendly ICT-based teaching books with a sample of 42 people consisting of 12 samples for the small group test and 30 samples for the large group test. The data obtained in this study were analyzed using qualitative analysis and quantitative analysis. Qualitative data analysis was obtained from questionnaires and quantitative data obtained from the results of the pre-test and post-test at the implementation stage. Based on the results of the calculation of the data, it was obtained that the data were normally distributed and homogeneous, so that the inferior statistical test used the Independent Sample T-Test with a significance value of 0.05. Based on the test results of data analysis, it was found that the "child-friendly ICT" textbook that had been developed was valid, practical and effective. The results obtained prove that child-friendly ICT textbooks contribute to improving the professional competence of students. Child-friendly ICT textbooks not only provide new understanding and knowledge of ICT use in child-friendly learning, but also enhance the skills of prospective teachers in using ICT-based teaching materials.

  • Application of the Steepest Ascent Hill Climbing Algorithm in the Preparation of the Crossword Puzzle Board
    Yoppy Sazaki, Hadipurnawan Satria, Anggina Primanita, and Rezi Apriliansyah

    Proceeding of 2018 4th International Conference on Wireless and Telematics, ICWT 2018, Published: 8 November 2018 IEEE
    The crossword puzzle board has many board variations based on the letters arranged on the board. The Steepest Ascent Hill Climbing algorithm is applied to determine the optimal shape of the crossword board. The initial successor is selected by the most number of characters, the next succcessor is selected from the second longest character until all the answers are selected, then in the final step is to calculate the fitness value to evaluate the answer board formed by calculating the answer junction and the number of questions that can be used on the answer board. Testing in this research is done by testing the same number of columns and rows by obtaining the amount of fitness value that is not too significant different, this explains that the crossword board can be made. This study also proves that the more rows and columns the less number of black boxes in the cross-answer board.

  • A comparison application of the genetic and steepest ascent hill climbing algorithm in the preparation of the crossword puzzle board
    Yoppy Sazaki, Anggina Primanita, Hadipumawan Satria, and Rezi Apriliansyah

    Proceeding of 2018 12th International Conference on Telecommunication Systems, Services, and Applications, TSSA 2018, Published: 2 July 2018 IEEE
    This study has the purpose of applying, analyzing and comparing the effectiveness of the Genetic Algorithm and Steepest Ascent Hill Climbing Algorithm in the preparation of the crossword puzzle answer board. In the genetic algorithm the number of genes, chromosomes and population boundaries affects the form of the crossword puzzle obtained, the variation of the shape of the crossword puzzle and the value of the results of the genetic algorithm when the population is small and the large population will experience a stagnation of fitness value, which is the do not change. Whereas in the Steepest Ascent Hill Climbing Algorithm variations in the number of characters answers to crossword puzzles affect the fitness value at the intersection of the answers formed.

  • Pathfinding car racing game using dynamic pathfinding algorithm and algorithm A∗
    Yoppy Sazaki, Anggina Primanita, and Muhammad Syahroyni

    Proceedings - ICWT 2017: 3rd International Conference on Wireless and Telematics 2017, Volume: 2017-July, Pages: 164-169, Published: 7 February 2018 IEEE
    The game of a racing car is one of the simulation games that requires Non-Playable Character (NPC) as the opponent's choice of play when a player wants to play alone. In a race car game, the NPC requires pathfinding to be able to walk on the track and avoid obstacles to reach the finish line. Pathfinding method used by NPC in this game is Al A∗ Algorithm to find the shortest path on path and combined with Dynamic Pathfinding Algorithm to avoid static or dynamic obstacles in track. The experimental results show that the combination of the two methods gives better results compared to Al A∗. The combination of both methods can be implemented well in racing car games with unobstructed track conditions as well as track conditions with static obstacles. While on the path with dynamic barriers, the combination of both methods successfully passes the track only under certain conditions.

  • Comparison of A∗ and dynamic pathfinding algorithm with dynamic pathfinding algorithm for NPC on car racing game
    Yoppy Sazaki, Hadipurnawan Satria, and Muhammad Syahroyni

    Proceeding of 2017 11th International Conference on Telecommunication Systems Services and Applications, TSSA 2017, Volume: 2018-January, Pages: 1-6, Published: 29 January 2018 IEEE
    The game of a racing car is one of the simulation games that require Non-Playable Character (NPC) as the opponent's choice of play when a player wants to play on his own. In a race car game, the NPC needs pathfinding to be able to walk on the track and avoid obstacles to reach the finish line. Pathfinding method used by NPC in this game is Al Dynamic Pathfinding Algorithm to avoid the static and dynamic obstacles in track. The experimental results show that NPCs using combined Dynamic Pathfinding Algorithm and Algorithm A∗ get the results from NPCs that use only DPA Algorithm A∗ while the obstacle position and trajectory shape have a big effect on DPA.

  • Implementation of Affine Transform Method and Advanced Hill Cipher for securing digital images
    Yoppy Sazaki and Robby Sandhy Putra

    Proceeding of 2016 10th International Conference on Telecommunication Systems Services and Applications, TSSA 2016: Special Issue in Radar Technology, Published: 3 March 2017 IEEE
    Digital image security aims to protect the image of the confidential access by parties that do not have the authority. Security on the research done by encrypting and decrypting digital image in PNG, BMP and JPEG using two methods are Affine Transform and Advanced Hill Cipher. Affine Transform method for scrambling pixel positions and methods Advanced Hill Cipher to change the pixel values. The safety analysis of the methods Affine Transform and Advanced Hill Cipher using entropy and the correlation coefficient. This study proves that the combined method Affine Transform and Advanced Hill Cipher can be merged to digital image information security.

  • The development android-based SMS security software using ECDSA with boolean permutation
    Yoppy Sazaki, Megah Mulya, and Mely Arisandi

    Proceedings - ICWT 2016: 2nd International Conference on Wireless and Telematics 2016, Pages: 26-30, Published: 3 March 2017 IEEE
    SMS (Short Message Service) is a messaging service in the mobile communication environment. In sending messages via SMS, message security is essential in order to maintain the integrity of the authenticity of the messages. Messages are secured not only in the aspect of confidentiality, but also on how the delivered message is not altered by someone. To overcome these problems, digital signature is required. Elliptic Curve Digital Signature Algorithm (ECDSA) with Boolean Permutation (BP) is one of the algorithms used for the process of adding and verifying the digital signature on the message. ECDSA is a public key cryptographic algorithm that is suitable to be implemented on devices with limited resources such as, mobile device or mobile phone. This is because the keys of ECDSA have relatively smaller than other public key cryptographic algorithms. ECDSA and Boolean Permutation can be implemented on mobile devices based on Android, and be able to verify the authenticity and maintain the integrity of SMS sent with several characteristics, such as, SMS that contains of letters, numbers, emoticons with the length of SMS that can be authenticated is 4 SMS - long in one delivery process (long messages).

  • Musical note recognition using Minimum Spanning Tree Algorithm
    Yoppy Sazaki, Rosda Ayuni, and S. Kom

    Proceedings of 2014 8th International Conference on Telecommunication Systems Services and Applications, TSSA 2014, Published: 23 March 2015 IEEE
    Musical Notes are notes which is placed in staff. This research was developed a musical note recognition software using Minimum Spanning Tree Algorithm. This software was developed to help beginner in learning music especially in recognizing musical notes. The input for this software was musical notes image and the output were information of musical note which is name of musical note and beat's length sound of recognized musical note. There were four pre-processing involved in this research namely Sobel edge detection, binarization, segmentation and scaling then the result from pre-processing was used in training process. Accuracy of musical note recognition using this algorithm reached 97.9 per cent out of 97 trained data and 97.4 per cent out of 40 tested data.