Judul: Karakteristik Glued Laminated Timber dari Tiga Jenis Kayu Berdiameter Kecil dengan Dua Ketebalan Lamina
Abstrak: Diversifikasi pemanfaatan jenis kayu termasuk yang berasal dari hutan rakyat dan hutan tanaman merupakan salah satu upaya memenuhi kebutuhan kayu yang terus bertambah sekaligus tetap menjaga kelestarian hutan alam. Kurang lebih 10 juta Ha lahan sedang dikembangkan untuk tanaman jenis cepat tumbuh, seperti kayu Sengon (Falcataria moluccana Miq.), kayu Manii (Maesopsis eminii Engl.), dan kayu Mangium (Acacia mangium Willd.). Kayu dari jenis cepat tumbuh (fast growing species) umumnya mempunyai diameter kecil (kurang dari 30 cm), siklus tebang pendek (5-10 tahun), dan umumnya memiliki kandungan cacat tinggi dan keawetan yang rendah dibandingkan dengan kayu dari hutan alam. Ketiga jenis kayu cepat tumbuh tersebut paling banyak ditanam untuk penggunaan bukan struktural dan dapat memenuhi kebutuhan kayu yang tak dapat dipenuhi oleh hutan alam. Penelitian ini bertujuan untuk menghasilkan glued laminated timber (glulam) yang memenuhi standar kayu struktural dalam contoh kecil dari tiga jenis kayu berdiameter kecil yaitu, mangium, manii, dan sengon. Ukuran glulam yang dibuat 5×7×160 cm (tebal, lebar, dan panjang). Glulam dibuat dengan kombinasi tiga dan lima lapisan lamina berukuran 1.7 cm dan 1 cm (t). Lamina direkat dengan menggunakan perekat isosianat, berat labur 280 g/m2 dengan kempa dingin, tekanan 10 kg/cm2 selama 3 jam. Glulam dibuat dari jenis kayu yang sama dan kombinasi bagian face back dari mangium dan bagian core dari manii atau sengon. Kayu solid digunakan sebagai pembanding terhadap glulam yang dihasilkan.. Pengujian sifat fisis, mekanis, dan delaminasi didasarkan pada standar JAS 234:2003. Hasil penelitian menunjukkan bahwa sifat glulam yang dihasilkan tidak berbeda nyata dengan kayu solidnya, terkecuali untuk kadar air glulam yang lebih tinggi dan keteguhan geser glulam lebih rendah dibandingkan dengan kayu solidnya. Jenis kayu mempengaruhi sifat glulam yang dihasilkan, tetapi antara glulam tiga lapis dan lima lapis tidak ada perbedaan yang nyata. Semua glulam resisten terhadap delaminasi perlakuan perendaman air dingin dan panas. Glulam yang berhasil memenuhi standar JAS untuk kayu struktural yaitu, glulam mangium tiga dan lima lapis, glulam manii lima lapis, dan glulam mangium-manii lima lapis.
Keyword: Glulam, kayu solid, kayu berdiameter kecil, standar JAS, delaminasi

Judul: Karakteristik Balok Laminasi (Glulam) Kayu Ekaliptus (Eucalyptus urophylla ST. Blake)
Abstrak: The use of wood for structural purposes requires a large dimension and long span as well as specific requirements of high strength. On the other hand, a lot of wood available today is wood from plantations with fast growing species of small diameter and generally have inferior properties such as defects content, natural durability and strength compared to wood from natural forests. One common way to get the wood to the desired dimension is the lamination technique. One of the laminate product used as a structural material is laminated timber. The aim of the study was glulam composed by three laminas thickness from eucalyptus wood. Three laminas 1cm, 1.5cm, 2cm thickness, were prepared in this study. Each laminae was tested by non destructive evaluation of deflection method to determine Modulusof Elasticity (MOE). The highest MOE of laminae was placed at the outside of glulam, then between laminas were glued by isocyanate resin. The dimension of glulam was (8 x 6 x 110) cm in thick, width, and length. The physical and mechanical properties of glulam were evaluated refering to standard JAS 234:2003. The physical properties of glulam timber of moisture content was in average value of 13.37%. The density mean of glulam timber were 0,65g/cm³ to glulam A composed by 1cm thickness of laminae, 0,63g/cm³ to glulam B composed by 1.5cm thickness of laminae, 0,56g/cm³ to glulam C composed by 2cm thickness of laminae. Delamination properties of hot and cold water were 25.2% and 4.99% for glulam A, 45.9% and 8.03% for glulam B, 73.86% and 0% for glulam C. The average value of mechanical properties Modulus of Elasticity (MOE) were 10.06x10⁴ kgf/cm² for glulam A, 7.42x10⁴ kgf/cm² for glulam B, and 5.63x10⁴ kgf/cm² for glulam C. The Modulus of Rupture (MOR) of glulam beams were 561 kgf/cm², 424 kgf/cm², and 327 kgf/cm² for glulam A, glulam B, and glulam C, respectively. Average value of shear strength properties were 98.42 kg/cm² for glulam A, 90.23 kg/cm² for glulam B, 79.01 kg/cm² for glulam C. Moisture content and delamination on cold water glulam timber were in compliance with JAS standards 234: 2003 while the delamination on heat water not fullfill to meet the standards. The MOE and MOR values the glulam timber (except MOE laminated timber with a thickness of 1.5 cm and 2 cm) were in compliance with JAS standards 234: 2003.
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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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