Judul: Effect of Drill Hole Depth on Various Tree Diameters on Pine Oleoresin Productivity
Abstrak: Penyadapan pohon pinus cenderung dilakukan dengan kedalaman yang sama pada setiap diameter pohon. Kedalaman lubang sadap dapat disesuaikan dengan diameter pohon. Penelitian ini bertujuan mengetahui pengaruh kedalaman lubang bor dan diameter pohon terhadap produktivitas oleoresin pinus serta menentukan kedalaman lubang bor pada setiap kelas diameter pohon pinus. Penyadapan pinus menggunakan metode bor dengan perlakuan kedalaman lubang bor 2 cm, 4 cm, dan 6 cm. Hasil penelitian menunjukkan semakin besar kedalaman lubang bor maka semakin banyak oleoresin yang dihasilkan. Produktivitas oleoresin meningkat seiring dengan meningkatnya diameter dan kedalaman lubang sadap., The tapping of pine trees tends to be the same depth for each tree diameter. The depth of the tapping hole can be adjusted according to the diameter of thetree. This study aims to determine the effect of tapping hole and tree diameter on pine oleoresin productivity and to determine the depth of the tapping hole for each diameter class of pine trees. Tapping the pine using the drilling method with a tapping hole of 2 cm, 4 cm, and 6 cm. The result showed that the greater depth of the tapping hole, the more oleoresin was produced. The greater the depth of tapping hole and the tree diameter, the higher the productivity of the oleoresin produced.
Keyword: drilling method, oleoresin productivity, pine trees, tapping hole depth, tree diameter

Judul: The effect of pipe perforation on the productivity  of pine oleoresin using the drill method
Abstrak: Metode bor merupakan metode tertutup sehingga udara yang berada di dalam wadah penampung tidak terhubung dengan udara luar. Ketika oleoresin keluar dari saluran getah maka akan menekan udara yang ada di dalam wadah penampung dan terjadi tekanan udara balik yang menghambat keluarnya getah. Penelitian ini menggunakan 5 perlakuan berbeda yaitu perlakuan A dengan metode bor dan penampung getah berupa mangkok plastik tertutup, perlakuan B dengan metode bor menggunakan pipa yang tidak dilubangi, perlakuan C berupa metode bor tanpa pipa, perlakuan D berupa metode bor menggunakan pipa yang telah dibuat 1 lubang, dan perlakuan E berupa metode bor menggunakan pipa yang telah dibuat 2 lubang. Hasil penelitian menunjukkan metode bor dengan pipa yang telah dibuat 2 lubang memberikan hasil yang paling tinggi. Sehingga penggunaan pipa yang dibuat 2 lubang dapat dijadikan solusi dalam penyadapan oleoresin pinus agar menghasilkan getah yang lebih banyak dibandingkan metode bor dengan pipa yang tidak dilubangi., The drill method is a method of closing the air that is in the container not connected to the outside air. When oleoresin comes out of the sap channel, it will press on the container and air pressure will occur which inhibits the release of sap. This study used 5 different treatments, namely treatment A with a drill method and a sap reservoir in the form of a closed plastic bowl, B with a drill method using a pipe that is not perforated, treatment C in the form of a drill method without a pipe, treatment D in the form of a drill method using a pipe that has been made 1 hole, and treatment E in the form of a drill method using a pipe that has been made 2 holes. The results showed that the drill method with a pipe that had 2 holes made gave the highest results. So that the use of pipes made of 2 holes can be used as a solution in tapping pine oleoresin to produce more sap compared to the drill method with pipes that are not perforated.
Keyword: air, drill method, pipe perforation, presussure, productivity

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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