Desain didaktis berbasis Permainan Tradisional Engklek di Sekolah Dasar

Abstract This research motivated by the findings of learning obstacles experienced students in material around square. This is known based on the results of  test questions conducted during preliminary study to fourth grade elementary school students. To overcome  learning obstacles experienced by students, researchers will design a didactic design. The purpose of this study is to describe the didactic design on the material around square and describe the students' responses the implementation of didactic design. The didactic design can be interpreted  learning design that emphasizes the didactic aspect, namely the teacher's teaching method. This study uses method with a Didactical Design Research (DDR) research design consisting of three research stages, namely a prospective analysis of the didactic situation before learning (prospective analysis) in the form of a Hypothetical Didactic Design including ADP (Pedagogical Didactic Analysis), metapedadidactive analysis, and retrospective analysis (retrospective analysis), with data collection techniques used in the form of interviews, observations, and attitude scales. The research subjects were 26 students in grades IV and VI and 1 teacher for grade IV at SDN 1 Sindangrasa. Based on results of study, through application of the didactic design carried out in stages I and II,   can help overcome learning obstacles experienced by students in the material around a square. This is shown from the students' responses on the attitude scale, results of the LAS (Student Activity Sheet) work and interviews with teachers. In addition,   didactic design is able to create a fun and meaningful learning atmosphere for students. Keywords: learning obstacle, didactical design research, square, meaningful learning, LAS Abstrak Penelitian ini dilatarbelakangi oleh adanya temuan learning obstacle  yang dialami siswa pada materi keliling persegi. Hal ini diketahui berdasarkan hasil soal tes yang dilakukan pada saat studi pendahuluan kepada siswa kelas IV Sekolah Dasar. Untuk mengatasi learning obstacle yang dialami siswa, peneliti akan merancang sebuah desain didaktis. Tujuan dari penelitian ini adalah untuk mendeskripsikan desain didaktis pada materi keliling persegi serta memaparkan respon siswa dan guru terhadap implementasi desain didaktis tersebut. Desain didaktis dapat diartikan sebagai desain pembelajaran yang lebih menekankan pada aspek didaktik yakni cara pengajaran guru. Penelitian ini menggunakan metode Didactical Design Research (DDR) yang terdiri dari tiga tahap penelitian, yakni analisis situasi didaktis sebelum pembelajaran (prospective analysis) berupa Desain Didaktis Hipotesis termasuk ADP (Analisis Didaktis Pedagogis), analisis metapedadidaktif, dan analisis retrospektif (retrospective analysis), dengan teknik pengumpulan data yang digunakan berupa wawancara, observasi, dan skala sikap. Subjek penelitian yaitu 26 siswa kelas IV dan VI serta 1 guru kelas IV SDN 1 Sindangrasa. Berdasarkan hasil penelitian, melalui penerapan desain didaktis yang dilakukan pada tahap I dan II dapat membantu mengatasi learning obstacle yang dialami siswa pada materi keliling persegi. Hal ini ditunjukkan dari respon siswa pada skala sikap, hasil pengerjaan LAS (Lembar Aktivitas Siswa) serta wawancara terhadap guru. Selain itu, desain didaktis mampu menciptakan suasana pembelajaran yang menyenangkan dan bermakna bagi siswa.  Kata kunci : hambatan belajar, desain didaktis, persegi, pembelajaran bermakna, LAS

Secure Communication Using Steganography in Image Processing

Research in information security and secrecy is becoming more and more important, as well as, demanding as the information is exponentially exploding. There has been a good bit of focus on cryptography, but with cryptanalysis and crypto attacks, researches have looked into the alternative means, like steganography. Steganography conceals the message into the cover file. In this dissertation we have focused on image steganography and we have tried to improve the key parameters of the system which are capacity, imperceptibility and robustness. In the first part of the thesis the presented work comprises of two contributions. In the first contribution the secret information is preprocessed by using latest devised right translated gray substitution box and BCH error correction codes. This process enhances the security of the information as data retrieval is impossible without the information of mapping rule applied and secret key. Differential embedding to the LSBs of optimized chaotically selected pixels through GA is another step to make detection difficult and avoid error to propagate. In second contribution we introduce an advance technique for embedding based on representing cover image pixels using a new 13-bit prime series representation resulting into 3-times increase in capacity. The payload has been reduced by applying 2D DCT to secret image and thresholding of the coefficients ensuring high imperceptibility. An innovative algorithm has also been proposed to ensure the uniform spread of message into the cover image by adjusting average separation between the chaotically selected pixels of cover image for embedding based on size of secret information and cover image In the second part of the thesis the presented work is an application of compressed sensing. The main advantage we have gained is the huge increase in security of the information along with the payload reduction. Utilizing compressed sensing made the system more secure as reconstruction of the data is impossible without knowing the measurement basis, as the generation process of measurement basis is random and requires huge computations to predict them. We have presented two problems. The first contribution focuses on combining compressive sensing and steganography to enhance security of image steganography. The secret image is encrypted and compressed using compressive sensing. The encrypted data is then embedded to randomly selected pixels of cover image using a secret chaotic key. Simulation results presented show the efficient recovery and reconstruction of secret image using reduced payload. In the second contribution we have focused on security and payload capacity enhancement of an image steganography system for an audio message by using compressed sensing theory. However, in order to utilize compressed sensing, the audio message is first converted to an equivalent grayscale image which is sparsified using 2D-DCT and thresholding. The sparsified image is further compressed using the proposed compressed sensing algorithm which enhances the security to a high level and also payload capacity improves significantly, without losing imperceptibility of the system. The compressed image is embedded in chaotically chosen pixels of the cover image. At receiver the compressed sensing reconstruction algorithm is used to reconstruct the grayscale image which is then converted back to the audio message. Presented results indicate that the proposed system is highly imperceptible, secure and robust against various image processing attacks. It is able to reconstruct secret audio message with high PSNR value.