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Aplikasi Pengamanan Data Menggunakan Algoritma Steganografi Discrete Cosine Transform dan Kriptografi AES 128 BIT pada SMK PGRI 15 Jakarta Rahmawati, Rika; Rahardjo, Dani
Jurnal Teknik Informatika dan Sistem Informasi Vol 2 No 1 (2016): JuTISI
Publisher : Maranatha University Press

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (765.952 KB) | DOI: 10.28932/jutisi.v2i1.609

Abstract

SMK PGRI 15 Jakarta has a lot of important documents such as financial reports, document collaboration and other important papers. Document security is still not done correctly so that the stored information is still very vulnerable to unknown, retrieved and manipulated by parties who are not entitled to that information. One way that information safe is to use steganography techniques. So the objective of this thesis is to build desktop-based applications to secure the data (information) in order to be secret by inserting secret messages that have been encrypted in the form of an image file. Steganography algorithm used is DCT (Discrete Cosine Transform). Data that has been inserted into the previous image is already in encrypted with 128 bit AES algorithm, so that data confidentiality is guaranteed. Based on the results of experiments conducted in this study, File Embedded processors who do have an average completion time of 432.3 seconds, and managed to get a good quality Steganography with the average value of the relatively small MSE of 1.38 dB and flat -rata PSNR of 47.66 dB. While the process Extract Files that do have an average completion time of 139,6detik, as well as the success rate of 100%. By using Steganography DCT (Discrete Cosine Transform) and Cryptographic techniques AES (Advanced Encryption Standard) 128 bit is very helpful in maintaining the confidentiality of documents that are not easily read by people who are not entitled to the document. So the security issues faced by SMK PGRI 15 Jakarta can be resolved.
Sintesis Nanokomposit g-Al2O3-Fe2O3 untuk Adsorpsi wj Logam Cr(VI) Rahmawati, Rika; Suhendar, Dede
JURNAL ISTEK Vol 8, No 1 (2014): ISTEK
Publisher : JURNAL ISTEK

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Abstract

wp Penanganan limbah yang mengandung logam berat sering kali memerlukan biaya yang tidak murah. Penelitian ini bertujuan untuk mensintesis adsorben berskala nanometer berbahan murah dan metode sintesis dan uji aplikasinya yang sangat sederhana, yakni nanokomposit g-Al2O3-Fe2O3 untuk adsorben Cr(VI). Larutan Al(OH)3 dicampur dengan larutan amoniak sampai pH 4, kemudian ke dalamnya dicampurkan sukrosa dan FeCl3 sampai homogen (perbandingan mol Al(OH)3 : 0,25 FeCl3 : 0,33). Campuran tersebut dipanaskan pada suhu 120 °C sambil pengadukan sampai volumenya menjadi sekitar 2/3-nya, kemudian dipanaskan kembali pada 200 °C selama 24 jam. Padatan berbentuk butiran-butiran berwarna coklat yang dihasilkan kemudian digerus halus dan dicampur dengan kerosen secara homogen. Campuran diuapkan sampai kerosen habis. Serbuk halus berwarna coklat yang dihasilkan kemudian dikalsinasi pada suhu 800 °C selama 4 jam. Berdasarkan hasil analisis XRD diperoleh bahwa sintesis tersebut menghasilkan produk campuran yang didominasi fasa g-Al2O3 dengan kristalinitas rendah yang menunjukkan terbentuknya nanokomposit. Larutan K2Cr2O7 telah digunakan sebagai model larutan yang mengandung Cr(VI) untuk pengujian sifat adsorben nanokomposit tersebut. 2 gram nanokomposit diaduk dengan larutan K2Cr2O7 dengan konsentrasi Cr(VI) 56,7 ppm pada suasana asam (pH 2) sebanyak 50 mL pada variasi waktu 1 – 24 jam. Hasil kontak menunjukkan bahwa lamanya waktu kontak tidak memberikan perbedaan yang signifikan namun secara keseluruhan diperoleh rata-rata adsorpsi Cr(VI) sekitar 82,5% setelah pengadukan awal selama 1 jam. Oleh karena itu dapat disimpulkan bahwa nanokomposit g-Al2O3-Fe2O3 sangat efektif dan efisien sebagai adsorben zat pencemar Cr(VI) karena biaya bahan dan sintesisnya sangat murah, sifat mengadsorpsinya cepat, dan mengadsorpsi cukup banyak Cr(VI).
DESAIN DIDAKTIS BERBASIS MODEL INKUIRI UNTUK MENGEMBANGKAN KEMAMPUAN PEMECAHAN MASALAH MATEMATIS Rahmawati, Rika; Azizah, Isnaini Nur
MaPan : Jurnal Matematika dan Pembelajaran Vol 6, No 2 (2018): DECEMBER
Publisher : Jurusan Pendidikan Matematika

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.24252/mapan.2018v6n2a1

Abstract

Abstrak:Penelitian ini bertujuan untuk menghasilkan suatu produk pengembangan dalam bentuk desain didaktis dan mengetahui kemampuan pemecahan masalah matematis siswa. Data diperoleh dari wawancara, observasi dan tes kemampuan pemecahan masalah. Berdasarkan hasil uji coba lapangan nilai rata-rata sebesar 74,2% dan tingkat kelulusan 76,19%. Hasil tertinggi dari aspek pemecahan masalah adalah memahami masalah 90,48% dan nilai terendah adalah memeriksa kembali sebesar 56,55%. Kesimpulan penelitian ini bahwa hasil posttest menunjukkan indikator memahami masalah sudah baik artinya siswa mampu memahami masalah dengan menuliskan apa yang diketahui dan ditanyakan. Namun, pada indikator memeriksa kembali diperoleh presentase terendah, karena siswa jarang memeriksa kembali jawaban yang telah ditulis.Abstract:The research aims to create a developmental product in the form of didactical design in order to know the students’ ability of mathematical problem solving. The data were obtained from interview, observation, and problem solving skill test. Based on the results of field try-out, it was obtained the mean score of 74% with achievement level of 76.19%. The highest problem solving aspect was understanding the problem with the score of 90.48% and the lowest score was rechecking skill with the score of 56.55%. Based on the findings, the posttest results show that the indicator of understanding the problem is good, it means that the students are able to understand the problem by writing what they know and what is being asked, but the indicator of rechecking gets lowest presentation score because the students rarely recheck their written answers.
DIVERSITY OF RED ALGAE (RHODOPHYTA) ON MANGROVE ECOSYSTEM IN EKAS VILLAGES, EAST LOMBOK DISTRICT Gazhali, Mursal; Rahmawati, Rika; Puji Astuti, Sri; Sukiman, Sukiman
Fish Scientiae Vol 8, No 1 (2018): Fish Scientiae, Vol.1, No.1, Juni 2018
Publisher : Universitas Lambung Mangkurat

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.20527/fs.v8i1.211

Abstract

Mangrove ecosystem is a unique ecosystem with a mix of marine and terrestrial environment. Mangrove forests provide food and nutrients for other organisms such as fish, crustaceans, and algae. Red algae play an important role in maintaining the balance of ecosystems and food chains. This study aims to determine the types, morphological characteristics and key identification, the relationship of red algae types and substrate types to the ecosystem of mangrove forest in Dusun Ekas. This research is explorative descriptive by using purposive sampling method at 5 stations. Based on the results of the red algae study obtained as many as 14 species are: Bostrychia sp., B. radicans, B. tenella, Chondria sp., Laurencia sp., Polysiphonia sp., Murrayella sp., C. Leprieurii, C. Monostica, Gelidium sp ., Gelidium crinale, Catenella caespitosa, Catenella nippae and Catenella sp. Characteristics of the talus were found to have a cylindrical talus and some like leaves (blade). Red algae (Rhodophyta) found more in the station that dominated by Soneratia alba species. Ekosistem mangrove merupakan ekosistem yang unik dengan perpaduan pengaruh lingkungan laut dan daratan. Hutan mangrove menyediakan sumber makanan dan nutrisi untuk organisme lain seperti ikan, crustacea, dan alga. Alga merah berperan penting  menjaga keseimbangan ekosistem dan rantai makanan. Penelitian ini bertujuan untuk mengetahui jenis-jenis, ciri morfologi dan kunci identifikasi, hubungan jenis alga merah dan jenis substratnya pada ekosistem hutan mangrove di Dusun Ekas. Penelitin ini bersifat deskriptif eksploratif dengan menggunakan  metode purposive sampling pada 5 stasiun. Berdasarkan hasil penelitian alga merah yang diperoleh sebanyak 14 spesies yaitu: Bostrychia sp., B. radicans, B. tenella, Chondria sp., Laurencia sp., Polysiphonia sp., Murrayella sp., C. Leprieurii, C. Monostica, Gelidium sp., Gelidium crinale, Catenella caespitosa, Catenella nippae dan Catenella sp. Karakteristik talus yang ditemukan ada yang memiliki talus silindris dan ada yang seperti daun (blade). Alga merah (Rhodophyta) yang ditemukan lebih banyak pada stasiun yang memiliki mangrove jenis Soneratia alba. 
Analysis of the Effectiveness of Learning in the Use of Learning Modules Against Student Learning Outcomes Rahmawati, Rika; Lestari, Fitria; Umam, Rofiqul
Desimal: Jurnal Matematika Vol 2, No 3 (2019): Desimal: Jurnal Matematika
Publisher : Universitas Islam Negeri Raden Intan Lampung

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.24042/djm.v2i3.4557

Abstract

At present there are still students who have difficulty in learning, due to limited learning resources. One effort that can be done is the use of modules in learning. Modules are printed teaching materials designed to be studied independently by learning participants. This study aims to determine the effect of the use of modules on the learning outcomes of students in MTs Hasanuddin Teluk Betung. Through the analysis of diffrences in the average of mathematics learning outcomes between those who used modules and those who did not use modules. The method used in this study is experiments with quantitative exploratory levels. The basic data collection technique uses a test technique that is to determine students learning outcomes. Testing hypotheses by using the t-test statistical formula. Based on the results of hypothesis testing it was concluded that the average mathematics learning outcomes of students using modules were higher than students who did not use the module.