Judul: The Contribution of Tapping Pine Sap to the Welfare of the Community of Ronggur Nihuta Village Samosir Regency.
Abstrak: Getah pinus merupakan salah satu hasil hutan bukan kayu yang bernilai komersial dan potensial memiliki peluang dan nilai pasar yang tinggi. Hal ini membuat getah pinus dapat dimanfaatkan sebagai sumber pendapatan baru bagi masyarakat yang bertempat tinggal disekitar hutan, sehingga mampu berkontribusi terhadap pendapatan total rumah tangga dan berimplikasi terhadap kesejahteraan. Tujuan penelitian ini adalah menghitung kontribusi penyadapan getah pinus terhadap pendapatan rumah tangga masyarakat sekitar hutan dan menganalisis tingkat kesejahteraan rumah tangga penyadap getah pinus di Desa Ronggur Nihuta Kabupaten Samosir. Penelitian dilakukan menggunakan metode survey dengan pemilihan responden secara purposive berjumlah 49 orang. Data keadaan sosial dan ekonomi penyadap di lokasi penelitian dianalisis secara kualitatif dan kuantitatif. Hasil penelitian menunjukkan bahwa kontribusi hasil penyadapan getah pinus terhadap pendapatan rumah tangga penyadap tergolong besar yaitu 76,05%, akan tetapi berdasarkan kriteria kesejahteraan BPS, UMK Kabupaten Samosir, dan Bank Dunia sebagian besar keluarga penyadap getah pinus di Desa Ronggur Nihuta tergolong tidak sejahtera., Pine sap is a non-timber forest product that has commercial value and has the potential to have high market opportunities and value. This makes pine resin can be used as a new source of income for people who live around the forest, so that it can contribute to total household income and have implications for welfare. The purpose of this study was to calculate the contribution of tapping pine sap to household incomes of communities around the forest and to analyze the level of welfare of households tapping pine sap in Ronggur Nihuta Village, Samosir Regency. The study was conducted using a survey method with a purposive selection of respondents totaling 49 people. Data on the social and economic conditions of tappers at the research site were analyzed qualitatively and quantitatively. The results showed that the contribution of pine resin tapping to the household income of tappers was large, namely 76.05%, but based on the welfare criteria of BPS, UMK Samosir Regency, and the World Bank, most of the families of pine resin tappers in Ronggur Nihuta Village were classified as not prosperous.
Keyword: contribution, income, pine resin, tapper, welfare

Judul: Income Analysis of Pine Sap Tappers (Pinus merkusii) in RPH Sugihan, KPH Kediri
Abstrak: Pinus (Pinus merkusii) merupakan salah satu hasil hutan dengan kandungan getah yang bernilai ekonomi tinggi. Perum Perhutani melibatkan masyarakat sekitar hutan sebagai tenaga penyadap untuk meningkatkan produktivitas getah pinus serta kesejahteraan masyarakat. Penelitian ini bertujuan untuk menganalisis besar pendapatan petani penyadap getah pinus, menganalisis besar kontribusi pendapatan dari kegiatan penyadapan getah pinus terhadap pendapatan total, serta menganalisis karakteristik petani penyadap getah pinus di RPH Sugihan. Metode yang digunakan dalam pengambilan data adalah observasi, wawancara, dan dokumentasi. Hasil penelitian menunjukkan bahwa rata-rata pendapatan penyadap dari sektor sadapan getah pinus sebesar Rp 11.028.180,12 per tahun dengan persentase kontribusi 47,12% sedangkan rata-rata pendapatan dari sektor lain sebesar Rp 12.376.000 per tahun dengan persentase kontribusi 52,88% sehingga diperoleh pendapatan total per tahun sebesar Rp 23.404.180,12. Kegiatan sadapan getah pinus tetap berkontribusi terhadap pendapatan total dan dapat dimaksimalkan untuk meningkatkan pendapatan dan kesejahteraan penyadap., Pine (Pinus merkusii) is one of the forest products with high economic value sap content. Perum Perhutani involves the community around the forest as tappers to increase pine resin productivity and community welfare. This study aims to analyze the income of pine resin tappers, analyze the contribution of income from pine resin tapping activities to total income, and analyze the characteristics of pine resin tappers in RPH Sugihan. The methods used in data collection were observation, interview, and documentation. The results showed that the average income of tappers from the pine resin tapping sector was Rp 11.028.180,12 per year with a contribution percentage of 47,12% while the averageincome from other sectors was Rp 12.376.000 per year with a contribution percentage of 52,88% so that the total income per year was Rp 23.404.180,12. Pineresin tapping activities still contribute to total income and can be maximized to increase the income and welfare of tappers.
Keyword: pine resin, income, tappers

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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