Judul: The Effectiveness of the Instagram Account @infosumbar as a Media for Disseminating Information on Minangkabau History and Culture
Abstrak: Instagram menjadi salah satu media sosial terpopuler yang digunakan oleh masyarakat saat ini. Peluang tersebut digunakan oleh PT Infosumbar Media Kreasi untuk memanfaatkan Instagram sebagai media dalam menyebarkan informasi sejarah dan budaya lokal di tengah warisan kebudayaan Indonesia. Penelitian ini menganalisis efektivitas akun Instagram @infosumbar sebagai media penyebaran informasi sejarah dan budaya Minangkabau. Penelitian ini menghubungkan variabel terpaan penggunaan Instagram dengan tingkat efektivitas Instagram yang dilihat dari efek pesan komunikasi terhadap aspek kognitif, afektif, dan konatif pengikutnya. Penelitian ini dilakukan dengan pendekatan kuantitatif dengan metode survei dan observasi sebagai instrumen pengambilan data kuantitatif yang didukung dengan data kualitatif dari wawancara mendalam. Data kuantitatif diolah menggunakan uji korelasi dengan pemilihan responden yang menggunakan metode purposive sampling. Hasil penelitian menunjukkan terdapat hubungan nyata antara tingkat terpaan pengikut akun Instagram @infosumbar dengan tingkat efektivitas akun Instagram @infosumbar dalam aspek kognitif, afektif, dan konatif., Instagram is one of the most used social media by people today. PT Infosumbar Media Kreasi took this opportunity to use Instagram as a medium in disseminating information on local history and culture in the midst of Indonesia's cultural heritage. This study analyzes the effectiveness of the Instagram account @infosumbar as a medium for disseminating information on Minangkabau history and culture. This study connects the variable exposure to Instagram use with the level of effectiveness of Instagram seen from the effect of communication messages on the cognitive, affective, and conative aspects of followers. This research was conducted with a quantitative approach with survey and observation methods as a quantitative data collection instrument supported by qualitative data from in-depth interviews. Quantitative data was processed using a correlation test with the selection of respondents using a purposive sampling method. The results showed that there was a significant relationship between the level of exposure of followers of the Instagram account @infosumbar and the level of effectiveness of the Instagram account @infosumbar on cognitive, affective, and conative aspects.
Keyword: effectiveness, instagram, social media exposure

Judul: The Effectiveness of Instagram as a Medium for Dissemination of Public Information
Abstrak: Saat ini telah banyak instansi pemerintah yang menggunakan media sosial dalam penyampaian informasi publik. Dalam menyampaikan informasi publik ke media sosial, sangat penting untuk melihat keefektifan pesan agar dapat tersampaikan dengan baik kepada khalayak. Penelitian ini bertujuan untuk menganalisis tingkat efektivitas media sosial instansi pemerintah sebagai media penyebaran informasi publik menggunakan model AISAS (Attention, Interest, Search, Action, Share), serta menganalisis faktor-faktor yang berkorelasi dengan efektivitas media sosial instansi pemerintah sebagai media penyebaran informasi publik. Penelitian ini bersifat explanatory research, dengan pendekatan kuantitatif menggunakan metode survei dan didukung pendekatan kualitatif melalui wawancara mendalam. Hasil penelitian menunjukkan bahwa Instagram @satudikti cukup efektif dalam menyebarkan informasi publik dalam menarik perhatian audiens, mengunggah ketertarikan, mendorong audiens untuk bertindak, serta membagikan pengalamannya terkait Satudikti. Efektivitas penyebaran informasi publik melalui Instagram @satudikti berkorelasi dengan frekuensi, kualitas informasi, dan kualitas konten visual., Currently, many government agencies use social media to convey public information. In conveying public information to social media, it is very important to see the effectiveness of the message so that it can be conveyed well to the audience. This research aims to analyze the level of effectiveness of government agency social media as a medium for disseminating public information using the AISAS (Attention, Interest, Search, Action, Share) model, as well as analyzing factors that correlate with the effectiveness of government agency social media as a medium for disseminating public information. This research is explanatory research, with a quantitative approach using survey methods and supported by a qualitative approach through in-depth interviews. The research results show that Instagram @satudikti is quite effective in disseminating public information in attracting audience attention, uploading interests, encouraging audiences to take action, and sharing their experiences regarding Satudikti. The effectiveness of disseminating public information via Instagram @satudikti correlates with frequency, quality of information and quality of visual content.
Keyword: AISAS, Instagram, public information

Judul: Hamiltonian formulation for linear waves motion in two layers fluid
Abstrak: The surface wave could be considered as a wave that separates two fluids, namely water and air. Based on this assumption, it is introduced the interfacial wave, a wave between two layers of fluid with different density. The formulation of interfacial waves motion begins with deriving the base equation of irrotational ideal fluid. Furthermore, according to irrotational fluid assumption, the base equation can be stated in velocity potential. In this derivation, the fluids domain is assumed to be restricted by rigid lid boundary conditions, both at the upper and lower limit. Therefore, the interfacial waves motion can be explained in a hamiltonian formulation. In the hamiltonian formulation, total energy is defined as the sum of kinetic and potential energy. The hamiltonian system is obtained from reduction of kinetic energy by using the Dirichlet Neumann Operator. The resulted kinetic energy equation is nonlinear. Therefore, this form is linearized by first part of the Taylor expansion. This linearization gives a dispersion relation of linear wave. Based on this dispersion relation, the phase speed of the linear wave depends on the density ratio of the two layers fluid.
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