Judul: The Effect of Core Shape and Dimensions on the Physical and Mechanical Properties of Tali Bamboo Sandwich Panels
Abstrak: Bahan untuk produk mebel dan bangunan yang saat ini disukai adalah yang ringan tetapi kuat, salah satunya teknologi kayu komposit. Pengembangan material dengan struktur sandwich bertujuan untuk memperoleh material dengan bobot yang ringan dengan kekuatan serta kekakuan yang besar. Penelitian ini bertujuan mengetahui pengaruh bentuk core terhadap sifat fisis dan mekanis panel sandwich dari bambu tali serta mengetahui pengaruh dimensi core terhadap sifat fisis dan mekanis panel sandwich dari bambu tali. Pengukuran sifat fisis seperti kerapatan, kadar air, daya serap air, dan pengembangan tebal. Pengujian mekanisnya yaitu kuat tekan, MOR sejajar serat dan tegak lurus serat, MOE sejajar serat dan tegak lurus serat serta internal bond menggunakan UTM (Universal Testing Machine). Variasi dimensi contoh uji berukuran 3 cm, 4 cm, dan 5 cm, sedangkan variasi bentuk core yaitu heksagonal, persegi, dan segitiga. Berdasarkan data yang diperoleh dan analisis yang dilakukan, contoh uji terbaik memiliki core dengan dimensi sedang (4 cm) dan berbentuk segitiga., The currently preferred materials for furniture and building products are light but strong, one of which is composite wood technology. The development of materials with a sandwich structure aims to obtain materials with a light weight with great strength and stiffness. This research aims to determine the effect of core shape on the physical and mechanical properties of sandwich panels made of bamboo rope and to determine the influence of core dimensions on the physical and mechanical properties of sandwich panels made of bamboo rope. Measurement of physical properties such as density, water content, water absorption capacity, and thickness expansion. The mechanical tests are compressive strength, modulus of rupture parallel to the fiber and perpendicular to the fiber, modulus of elasticity parallel to the fiber and perpendicular to the fiber and internal bond using UTM (Universal Testing Machine). The variations in the dimensions of the test samples are 3 cm, 4 cm and 5 cm, while the variations in core shape are hexagonal, square and triangular. Based on the data obtained and the analysis carried out, the best test samples have cores with medium dimensions and a triangular shape.
Keyword: core dimensions, core shape, sandwich panels, tali bamboo

Judul: Physical and Mechanical Characteristics of Tali Bamboo Sandwich Panel with Variation in Dimensions and Number of Layers of Hexagonal Cells
Abstrak: Bambu dapat dipilih sebagai alternatif material lain seperti kayu solid, beton, dan baja. Penelitian ini bertujuan menganalisis pengaruh dimensi dan jumlah lapisan sel heksagon pada core terhadap sifat fisis dan mekanis panel sandwich. Bahan utama pembuatan panel berukuran 300 mm × 300 mm ini adalah bambu tali dan perekat polivinil asetat. Percobaan faktorial dengan pola rancangan acak lengkap diterapkan dengan dua faktor yaitu dimensi sel (kecil, sedang, dan besar) dan jumlah lapisan sel heksagon (2 lapis, 3 lapis, dan 4 lapis). Evaluasi sifat fisis dan mekanis panel sandwich dibandingkan dengan standar JIS A 5905-2003 untuk papan serat dan standar JIS A 5908-2003 untuk papan partikel. Hasil analisis membuktikan adanya pengaruh kombinasi dimensi sel dan jumlah lapisan sel heksagon pada kerapatan dan kuat tekan panel sandwich. Hasil yang paling optimal diperoleh dari panel sandwich dengan kombinasi sel berdimensi kecil berlapis empat yang menghasilkan nilai kadar air 10,18%; kerapatan 0,42%; kuat tekan 20,88 kg/cm2; MOE tegak lurus serat dan sejajar serat berturut-turut 4246 kg/cm2 dan 7883 kg/cm2; MOR tegak lurus serat dan sejajar serat berturut-turut 53,54 kg/cm2 dan 112,27 kg/cm2; serta internal bond 1,04 kg/cm2., Bamboo can be chosen as an alternative to other materials such as solid wood, concrete, and steel. This study aims to analyze the effect of dimensions and the number of layers of hexagonal cells in the core of sandwich panels on their physical and mechanical properties. The main material for making this 300 mm × 300 mm panel was tali bamboo and polyvinyl acetate adhesive. A factorial experiment with a complete randomized design pattern was applied with two factors namely cell dimension (small, medium, and large) and the number of layers of hexagonal cells (2 layers, 3 layers, and 4 layers). The evaluation of these sandwich panels physical and mechanical properties was compared to the JIS A 5905-2003 standard for fiberboards and the JIS A 5908-2003 standard for particleboards. The results of the analysis proved the effect of a combination of cell dimensions and the number of layers of hexagonal cells on the density and compressive strength of the sandwich panel. The optimum result was obtained from sandwich panels with a combination of small-dimensional and four-layered cells, which resulted in a moisture content of 10,18%; density of 0,42%; compressive strength of 20,88 kg/cm2; MOE in perpendicular and parallel to the grain were 4246 kg/cm2 and 7883 kg/cm2, respectively; while MOR in perpendicular and parallel to the grain were 53,54 kg/cm2 and 112,27 kg/cm2, respectively; and internal bond of 1,04 kg/cm2.
Keyword: mechanical properties, physical properties, sandwich panel, tali bamboo

Judul: A Continuous Vaccination Strategy in the SVIR Epidemic Model
Abstrak: Vaccination is conducted to minimize the spread of a disease. The vaccination is usually done several times within a fixed time interval. In the SVIR model, it is assumed that individuals do not get immediate immunity following a vaccination program. So according to process of vaccination on SVIR model, there are two strategies, i.e. the continuous vaccination strategy (CVS) and the pulse vaccination strategy (PVS). In this study, only the CVS strategy in epidemic model SVIR is considered. Results of the study indicate that dynamics of the CVS system depends on the basic reproductive number. If the basic reproductive number is less than one, then the disease-free fixed point is asymptotically stable. It means that the disease will eventually disappear from the population. Conversely, if the basic reproductive number is greater than one, then the endemic fixed point is asymptotically stable, which means that the disease will remain exist in the population. Simulation result shows that the vaccination would minimize the spread of disease by reducing the basic reproductive number. If the time for the vaccinated recipients to obtain the immunity, as well as a possibility of vaccinated recipients to be infected are neglected, then the disease will be eradicated. This condition is called an over-evaluating effect of vaccination.
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