In this digital era, transmitting data through a computer network has become common. Moreover, some applications have also been developed to do it. Nevertheless, users may not be aware of the security aspect of this data transmission, which can lead to disclosing this private message. In a case when a sensitive message is the object to transmit, a security mechanism should be applied. Data hiding is one of the methods introduced to work for this issue. In this algorithm, the message is embedded into the cover, such as an audio file, before being transmitted; on the other side, the recipient extracts it. However, the size of the message and the quality of the resulted stego data are still challenging. In this paper, we focus on these two problems by considering some factors: embedding space, embedding process, reducing, and smoothing steps. Firstly, the audio signal is discretized to obtain audio samples. Next, these samples are interpolated to provide spaces for hiding the secret. Considering that the quality of the generated stego audio is likely to drop, reducing and smoothing steps are designed. The experimental results show that this approach can improve the quality of the stego based on the specified payload capacity. That is, there is an increase in PSNR value of at least 10 dB, depending on the payload size and the methods.

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Requirement Engineering is one of stages in the software development. One of the challenges in requirements engineering is the use of tools in modeling the requirements. The number of requirements modeling applications does not guarantee that an analyst can model the needs appropriately for the complexity of the application, because the cost of modeling applications is too expensive to affect the use of such applications to model the requirements. Another problem faced by students on education is the difficulty in applying knowledge about software engineering. For example, if students are given a project from the industry, the requirements elicitation and modeling application are usually needed. The tools used in the industry are sometimes not suitable for education purposes. This paper aims to develop a tool for requirements modeling, to assist novice analyst in learning and classifying UML diagrams as well as learning the syntax. The tool is named RMTool, which is an object-oriented modeling tool based on web. Testing is conducted both on the developer and the user environment. Evaluation by end users involves 76 students as novice analyst to test the effectiveness and usefulness of modeling tool using questionnaire. The evaluation results show that the majority of students are satisfied using the application. Intisari-Rekayasa persyaratan atau kebutuhan adalah salah satu tahapan dalam pembangunan perangkat lunak. Salah satu tantangan dalam rekayasa kebutuhan adalah penggunaan aplikasi bantu dalam pemodelan kebutuhan. Banyaknya aplikasi pemodelan kebutuhan tidak menjamin seorang analis dapat memodelkan kebutuhan dengan tepat guna dikarenakan kompleksnya aplikasi kebutuhan yang ada. Relatif mahalnya aplikasi pemodelan juga memengaruhi penggunaan aplikasi tersebut untuk memodelkan kebutuhan. Masalah lain yang dihadapi siswa dalam dunia pendidikan adalah kesulitan menerapkan pengetahuan tentang rekayasa perangkat lunak dalam dunia nyata. Sebagai contoh, apabila siswa diberikan proyek dari dunia industri, biasanya siswa akan melakukan elisitasi kebutuhan dan memerlukan aplikasi pemodelan. Aplikasi yang digunakan di dunia industri kadangkala tidak cocok untuk digunakan dalam dunia pendidikan. Makalah ini bertujuan merancang perangkat lunak pemodelan kebutuhan guna membantu analis pemula dalam mempelajari dan mengklasifikasikan diagram UML serta mempelajari syntax dan memodelkan kebutuhan. Aplikasi yang dibangun bernama RMTool, yang merupakan aplikasi pemodelan kebutuhan berorientasi objek berbasis web. Setelah RMTool dibangun, dilakukan pengujian, baik di lingkungan pengembang maupun di lingkungan pengguna. Evaluasi RMTool di lingkungan pengguna melibatkan 76 siswa sebagai analis pemula untuk menguji efektifitas dan kegunaan aplikasi pemodelan menggunakan kuesioner. Berdasarkan hasil evaluasi dapat disimpulkan bahwa mayoritas siswa puas menggunakan aplikasi tersebut.

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The current development of context-awareness has introduced various emerging research areas to reduce complexity in developing context aware applications by applying service-oriented approach in managing context and establish context service. The establishment of context service will enable context aware systems to access and utilize context from context providers without paying necessary attention on how context information are composed and managed. Frequent changes of available context providers with different context quality are common phenomena in mobile environment. Hence, dealing with quality of context is a very important issue to provide reliable services for context management in this environment. We have identified some key requirements to establish context service and propose a service-oriented framework to facilitate context management in mobile environment. Furthermore we show our approach to deal with problem in providing appropriate context based on its quality requirements and the preferences of the corresponding context request.

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