Judul: Karakteristik Cross Laminated Timber (CLT) Kayu Jabon Dengan Perekat Melamin Formaldehida (MF) Modifikasi Aplikasi Kempa Dingin
Abstrak: Cross Laminated Timber (CLT) adalah papan komposit yang terbuat dari kayu berlapis-lapis yang ditumpuk tegak lurus serta ditingkatkan stabilitas dimensinya. Tujuan dari penelitian ini adalah menganalisis sifat fisis dan mekanis CLT dari kayu jabon (Anthocephalus cadamba) dengan perekat MF modifikasi. Modifikasi perekat MF dilakukan untuk penggunaan kempa dingin. Berat labur CLT terdiri atas tiga variasi yaitu 250, 280 dan 300 g/m2. Evaluasi karakteristik perekat MF modifikasi berupa kadar padatan, waktu gelatinasi, viskositas, pH, FTIR dan DMA. Evaluasi karakteristik fisis dan mekanis berupa kerapatan, kadar air, delaminasi, MOE sejajar serat muka dan tegak lurus serat muka (flatwise & edgewise), MOR sejajar serat muka dan tegak lurus serat muka (flatwise & edgewise), tekan sejajar serat, tekan tegak lurus serat dan keteguhan rekat. Berat labur CLT hanya berpengaruh nyata terhadap nilai delaminasi dan keteguhan rekat. CLT dengan berat labur 300 g/m2 memiliki karakteristik sifat fisis mekanis yang paling optimum. Semakin tinggi berat labur perekat, semakin tinggi sifat fisis dan mekanisnya. Kualitas produk kurang baik karena tekanan kempa yang minim pada saat pengempaan CLT., Cross Laminated Timber (CLT) is a composite board made of multilayered timber that is stacked perpendicularly and its dimensional stability is enhanced. The objective of this research was to analyze the physical and mechanical properties of CLT from jabon wood (Anthocephalus cadamba) with modified MF adhesive. Modified MF adhesive was carried out for cold pressing applications. The glue spreads of CLT consist of three variations, namely 250, 280, and 300 g/m2. Evaluation of the characteristics of modified MF adhesive in the form of solids content, gelation time, viscosity, pH, FTIR, and DMA. Evaluation of the physical and mechanical properties was carried out including density, moisture content, delamination, MOE parallel and perpendicular to the face grain (flatwise & edgewise), MOR parallel and perpendicular to the face grain (flatwise & edgewise), compression parallel to the grain, compression perpendicular to the grain, and bonding strength. The glue spreads of CLT only significantly affected the value of delamination and bonding strength. CLT with a glue spread of 300 g/m2 has the most optimum mechanical and physical properties. The higher the glue spread, the higher the physical and mechanical properties. The poor product quality because of minimal compression pressure during CLT compression.
Keyword: CLT, glue spreads, jabon wood, melamine formaldehyde, modification

Judul: Karakteristik Cross Laminated Timber Kayu Jabon berdasarkan Ketebalan dan Orientasi Sudut Lamina
Abstrak: Along with the technological developments, a new method of laminated timber has been found, called by cross laminated timber (CLT). CLT is an engineered product of wood composed of some lamina or layers bonded in an arrangement of layers crossing one another. The purpose of this research was to design a panel of CLT by modifying the combined patterns of different thickness and orientation angles of lamina in order to have the highest strength values and determine the characteristics of CLT panels as structural timber. The study results are expected to provide alternative benefits or uses of wood from the community forests as a product of CLT, give information to the people about the quality of CLT panel from the community forest and increase the chance of timber development from the community forests for structural wood products. The thickness of lamina applied in the manufacture of CLT panels were 1.0, 1.67, 2.0 and 3.0 cm with the width of 15 cm and the length of 120 cm. CLT panel was formed of three layers or lamina with the cross-sectional size of 5 cm x 15 cm x 120 cm based on the value of its MOE with three types of combination in lamina thickness, namely type A1 (1 cm, 3 cm, and 1 cm), type A2 (1 cm, 2 cm, and 1 cm), and type A3 (1.67 cm, 1.67 cm, and 1.67 cm). The middle layer was based on the orientation angles of lamina: 0°, 30°, 45°, 60°, and 90°. The adhesive used was water based polymer isocyanate (WBPI) with the glue spreading of 280 g/m2 for both surfaces. Testing was based on ASTM D 143 (2005) and JAS 234:2003 standard. The result showed that the combined thickness of lamina had a significant effect on the mechanical properties of MOE, MOR and compressive strength parallel to fibers on CLT panels. The lamina orientation angles had a significant effect on the physical properties of volume shrinkage and expansion on CLT panels. On the other hand, as for the mechanical properties, the angle orientation of lamina showed a significant effect on MOE, MOR, compressive strength parallel to fibers, and the bonding strength of CLT panels. The interaction between a combined thickness of lamina and angle orientation only significantly influenced the compressive strength parallel to fibers of CLT panels. Meanwhile, based on the scoring of CLT panel, the combined thickness of lamina type A3 and the angle orientation of 30o had the best properties. This is because the number of connections on the angle orientation of 30o Key words: Cross laminated timber, jabon wood, physical and mechanical properties, less than those of other angle orientations. The resulted analysis of the whole or intact timber (control) showed that in general CLT panels have better properties of volume shrinkage and expansion than the intact original timber.
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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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