Judul: Physical Properties and Color Changes in Polystyrene Impregnated Mangium (Acacia mangium) Glulam
Abstrak: Glue Laminated Timber (Glulam) merupakan salah satu produk komposit dari kayu. Tujuan penelitian ini untuk mengetahui pengaruh impregnasi polistirena terhadap sifat fisis dan perubahan warna glulam dari kayu mangium (Acacia mangium). Tujuan perlakuan impregnasi untuk peningkatan sifat fisis kayu dengan cara memasukkan monomer stirena ke dalam kayu. Evaluasi karakteristik yang dilakukan adalah polymer loading, kerapatan, kadar air, delaminasi, dan perubahan warna. Hasil penelitian menunjukkan bahwa nilai rata-rata polymer loading, kerapatan, kadar air, delaminasi, dan perubahan warna masing-masing adalah 5,25 %, 0,69-0,80 g·cm-3, 10,07-11,58 %, 6,4-19,69 %, dan 7,04. Pembuatan glulam impregnasi polistirena kayu mangium dapat meningkatkan sifat fisis pada glulam. Nilai kerapatan tertinggi dan kadar air terendah didapatkan pada glulam impregnasi polistirena. Impregnasi polistriena memberikan pengaruh yang berbeda (different colors) terhadap perubahan warna kayu mangium. Warna kayu menjadi lebih gelap setelah terimpregnasi polistirena. Nilai delaminasi glulam impregnasi polistirena tidak sesuai standar., Glue Laminated Timber (Glulam) is a composite product made of wood. The purpose of this study was to determine the effect of polystyrene impregnation on the physical properties and color changes of glulam from mangium (Acacia mangium). The purpose of impregnation treatment is to improve the physical properties of wood by incorporating styrene monomer into the wood. Characteristic evaluation carried out were polymer loading, density, moisture content, delamination, and color change. The results showed that the average values of polymer loading, density, moisture content, delamination, and color change were 5.25%, 0.69-0.80 g·cm-3, 10.07-11.58 %, 6.4-19.69%, and 7.04. The manufacture of glulam impregnation of mangium wood polystyrene can improve the physical properties of the glulam. The highest density values and the lowest water content were found in polystyrene impregnated glulam. Polystyrene impregnation has a different effect (different colors) on the color change of mangium wood. The color of the wood becomes darker after being impregnated with polystyrene. The delamination value of polystyrene impregnated glulam is not up to standard.
Keyword: fast growing wood, glulam, impregnation, isocyanate, mangium

Judul: Physical Properties and Color Changes in Polystyrene Impregnated Rubber Wood Glulam (Hevea brasiliensis)
Abstrak: ABSTRAK AZMAL ICHSANUL JOHAN. Sifat Fisis dan Perubahan Warna pada Glulam Kayu Karet (Hevea brasiliensis) Terimpregnasi Polistirena. Dibimbing oleh YUSUF SUDO HADI. Kayu merupakan bahan utama pada konstruksi bangunan perumahan, terutama untuk perumahan sederhana, Kayu karet merupakan salah satu kayu bermutu rendah yang berpotensi dan bisa dimanfaatkan untuk bahan baku glulam. Tujuan penelitian ini adalah untuk mengetahui pengaruh proses impregnasi polistirena terhadap sifat fisis dan perubahan warna glulam dari kayu karet (Hevea brasiliensis). Perlakuan impregnasi merupakan salah satu teknologi peningkatan mutu kayu yang dapat mengatasi atau memperbaiki kelemahan karakteristik kayu. Glulam dibuat menggunakan perekat isosianat dengan berat labur 280 g·m-2. Penilaian karakteristik yang dilakukan antara lain polymer loading, kerapatan, kadar air, delaminasi, dan perubahan warna. Nilai rata – rata polymer loading, kerapatan, kadar air, delaminasi dan perubahan warna masing – masing yaitu 6,89 %; 0,67 – 0,74 g·cm-3; 8,19 – 11,25 %; 29,13 – 32,36 %; dan 2,04 ± 1,20. Glulam terimpregnasi polistirena memiliki nilai sifat fisis yang lebih baik dibandingkan dengan kayu tanpa impregnasi polistirena. Nilai kerapatan tertinggi dan kadar air yang memenuhi standar JAS 234 didapatkan oleh glulam terimpregnasi polistirena. Glulam terimpregnasi polistirena memiliki nilai sifat fisis yang lebih baik dibandingkan tanpa impregnasi polistirena. Nilai delaminasi glulam impregnasi stirena memiliki standar deviasi yang tinggi. Perubahan warna kayu karet setelah impregnasi berubah menjadi lebih cerah setelah terimpregnasi polistirena. Kata kunci: glulam, impregnasi, isosianat. kayu karet, polistirena, ABSTRACT AZMAL ICHSANUL JOHAN. Physical Properties and Color Changes in Polystyrene Impregnated Rubber Wood Glulam (Hevea brasiliensis). Supervised by YUSUF SUDO HADI. Wood is the main material in the construction of residential buildings, especially for simple housing, rubber wood is one of the low-quality wood that has the potential and can be used as raw material for glulam. The purpose of this study was to determine the effect of the polystyrene impregnation process on the physical properties and color changes of glulam from rubber wood (Hevea brasiliensis). Impregnation treatment is one of the wood quality improvement technologies that can overcome or improve the weakness of wood characteristics. Glulam was made using isocyanate adhesive with a bulk weight of 280 g·m-2. Characteristics assessment carried out included polymer loading, density, moisture content, delamination, and color change. The average value of polymer loading, density, moisture content, delamination and color change are 6.89 %; 0.67 – 0.74 g·cm-3; 8.19 – 11.25 %; 29.13 – 32.36 %; and 2.04 ± 1.20. Glulam impregnated with polystyrene has better physical properties than wood without impregnated polystyrene. The highest density values and water content that met the JAS 234 standard were obtained by polystyrene impregnated glulam. Glulam impregnated with polystyrene has better physical properties than without impregnated polystyrene. The delamination value of styrene impregnated glulam has a high standard deviation. The color change of rubber wood after impregnation changes to a brighter color after impregnation with polystyrene.
Keyword: glulam, impregnation, isocyanate, polystyrene, rubber wood

Judul: Dynamical System of Hepatitis B in Three Groups with Vaccination
Abstrak: The aim of this study is to modify the hepatitis B transmission model in three age groups involving vaccination from the model conducted by Zhoe and Zhang.The method used is to analyze the stability of the fixed point and its basic reproduction number (R_0). Performed stability analysis and numerical simulation to see population dynamics. Next, a sensitivity analysis of the parameters was carried out to see its effect on R_0. From the analysis obtained two fixed points, namely non-endemic and endemic fixed points. Non-endemic fixed points are locally asymptotically stable if R_0 <1 Meanwhile, the endemic fixed point is locally asymptotically stable if R_0 > 1. Hepatitis vaccination affects the number of susceptible population, because the more successful the vaccination, the smaller the number of susceptible populations so that the smaller the population will be infected.
Keyword: Dynamic, Hepatitis B, Vaccine, Mathematical model