Judul: Efektivitas Media Sosial Sebagai Media Promosi Taman Hutan Raya IR. H. Djuanda di Masa Pandemi Covid-19
Abstrak: Pandemi Covid-19 mengakibatkan adanya pemberlakuan PSBB dan menimbulkan menurunnya kegiatan berwisata. Penelitian bertujuan menganalisis efektivitas media sosial sebagai media promosi dan melihat hubungannya dengan karakteristik konsumen, karakteristik media sosial, dan kredibilitas media sosial, serta hubungan antara efektivitas media sosial dengan keputusan berkunjung di masa pandemi Covid-19. Metode yang digunakan yaitu metode kuantitatif menggunakan kuesioner untuk 50 responden dengan teknik accidental sampling. Hasil penelitian menunjukkan bahwa efektivitas media sosial selama pandemi Covid-19 sudah cukup bagus dan memiliki hubungan dengan keputusan berkunjung wisatawan. Selain itu, karakteristik konsumen tidak memiliki hubungan dengan efektivitas media sosial sebagai media promosi selama pandemi Covid-19 sementara Karakteristik media sosial dan kredibilitas media sosial memiliki hubungan dengan efektivitas media sosial sebagai media promosi selama pandemi Covid-19., The Covid-19 pandemic has resulted in the implementation of PSBB and has led to a decrease in tourist activities. The study aims to analyze the effectiveness of social media as a promotional media and its relationship with consumer characteristics, social media characteristics, and social media credibility, as well as the relationship between the effectiveness of social media and the decision to visit Djuanda Forest Park during the Covid-19 pandemic. The method used is a quantitative method using a questionnaire for 50 respondents with an accidental sampling technique. The results showed that the effectiveness of social media Djuanda Forest Park during the Covid-19 pandemic was good and had a relationship with the decision of tourists to visit Djuanda Forest Park. In addition, consumer characteristics do not have a relationship with the effectiveness of social media while social media characteristics and social media credibility have a relationship with the effectiveness of social media as a promotional media Djuanda Forest Park during the Covid-19 pandemic.
Keyword: covid-19, consumer characteristics, social media characteristics, social media credibility, visit decision

Judul: Efektivitas Media Sosial Instagram Sebagai Media Promosi Destinasi Wisata Alam Di Masa Pandemi Covid-19 ( Kasus: Objek Wisata Alam Air Terjun Sikulikap, Desa Doulu, Kecamatan Sibolangit, Kabupaten Karo, Sumatera Utara)
Abstrak: Pandemi COVID-19 mengguncang dunia dan memberikan dampak yang sangat luar biasa terhadap perekonomian negara termasuk di sektor pariwisata. Salah satunya adalah objek wisata Air Terjun Sikulikap yang tutup sementara dan harus menggencarkan promosi pasca pembukaan kembali melalui media sosial instagram. Tujuan dari penelitian ini adalah untuk menganalisis efektivitas media sosial Instagram sebagai media promosi destinasi wisata alam di masa pandemi COVID-19. Metode yang digunakan adalah metode kuantitatif dengan kuesioner online dan didukung dengan data kualitatif melalui wawancara mendalam. Responden yang digunakan adalah followers Instagram @airterjunsikulikap berjumlah 100 orang yang didapatkan melalui teknik accidental sampling. Hasil penelitian menunjukkan bahwa penilaian responden terhadap karakteristik konten media sosial Instagram termasuk dalam kategori tinggi untuk indikator kelengkapan informasi. Indikator desire memiliki nilai rataan paling tinggi dibanding indikator lainnya, dan karakteristik responden tidak menunjukkan hubungan yang signifikan dengan indikator attention (perhatian), interest (ketertarikan), desire (keinginan), dan action (tindakan). Kata kunci: pandemi COVID-19, Pariwisata, Media promosi, Instagram, The COVID-19 pandemic has shaken the world and has had a tremendous impact on the country's economy, including in the tourism sector. One of which was the Sikulikap Waterfall tourist attraction which was temporarily closed and had to intensify post-reopening promotions through Instagram social media. The purpose of this study was to analyze the effectiveness of Instagram social media as a medium for promoting natural tourist destinations during the COVID-19 pandemic. The method used is a quantitative method with an online questionnaire and is supported by qualitative data through in-depth interviews. Respondents used were Instagram followers @airterjunsiulikap totaling 100 people obtained through accidental sampling technique. The results showed that the respondents' assessment of the characteristics of Instagram's social media content was included in the high category for the completeness of information indicator, the desire indicator had the highest average value compared to other indicators, and the characteristics of the respondents did not show a significant relationship with the indicators of attention, interest, desire and action. Keywords: COVID-19 pandemic, Tourism, Promotional media,Instagram
Keyword: Covid-19 Pandemic, Tourism, Promotional media, Instagram

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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