Judul: The Strength of Betung Bamboo to Withstand Normal Force Compression and Tension
Abstrak: Bambu merupakan hasil hutan yang multiguna yaitu bahan baku mebel, kerajinan, alat musik, dan konstruksi. Penelitian ini bertujuan untuk mengukur sifat mekanis bambu betung yaitu kekuatan tekan sejajar serat, tarik sejajar serat, dan tarik tegak lurus serat serta menganalisis nilai 5% batas bawahnya. Ukuran contoh uji dan pengujian sifat mekanis mengacu pada BS ISO 22157:2019. Pengujian tekan sejajar dan tarik tegak lurus serat menggunakan UTM SATEC/Baldwin sedangkan pengujian tarik sejajar serat menggunakan UTM Chun Yen. Analisis data menggunakan aplikasi Easyfit 5.5 untuk mendapatkan nilai 5% batas bawah tiap pengujian. Rata-rata kuat tekan sejajar serat yang diperoleh yaitu sebesar 53,0 N/mm², sedangkan nilai rata-rata kuat tarik sejajar sebesar 109 N/mm². Rata-rata kuat tarik tegak lurus dengan ukuran lubang uji 25 dan 40 mm sebesar 2,53 dan 1,19 N/mm², sedangkan nilai rata-rata MOE tekan dan MOE tarik sejajar serat yaitu sebesar 2674 dan 9542 N/mm². Nilai 5% batas bawah untuk kuat tekan sejajar serat sebesar 38,1 N/mm², tarik sejajar serat sebesar 61,8 N/mm², sedangkan untuk kuat tarik tegak lurus sebesar 0,60 N/mm². Nilai 5% batas bawah kuat tarik tegak lurus yang lemah, membuat bambu tidak disarankan untuk dimanfaatkan ke arah tegak lurus seratnya. Nilai 5% batas bawah MOE tekan dan MOE sejajar serat yang diperoleh sebesar 1105 dan 6076 N/mm². Kata kunci: betung, kekuatan, tarik, tekan, nilai estimasi, Bamboo is multifunctional forest products such as furnitures, crafts, music instruments, and construction material. This research aims to determine the mechanical properties of betung bamboo, specifically, compression strength parallel to fiber, tension strength parallel and perpendicular to fiber, and its 5% exclusion limit value. The sample size and mechanical properties testing refers to BS ISO 22157:2019. Compression and tension strength parallel to fiber tested using UTM SATEC/Baldwin while tension strength perpendicular to fiber tested using UTM Chun Yen. Data analysis used Easyfit 5.5 to obtain 5% exclusion limit value of each test. The average value of compression strength and tension strength parallel to fiber were 53,0 N/mm² and 109 N/mm², respectively. The average value of tension strength perpendicular to fiber for 25 and 40 mm testing hole were 2,53 and 1,19 N/mm², while average MOE value of compression and tension strength parallel to fiber were 2674 and 9542 N/mm², respectively. The 5% exclusion limit value of compression strength parallel to fiber was 38,1 N/mm², tension strength parallel to fiber 61,8 N/mm², and 0,60 N/mm² for tension strength in perpendicular grain. The 5% exclusion limit value of tension strength in perpendicular grain was too weak, and it makes bamboo is not recommended to use at this property. The 5% exclusion limit MOE value of compression and tension strength in parallel grain were 1105 and 6076 N/mm², respectively. Keyword: betung, compression, estimate value, strength, tension
Keyword: betung, compression, estimate value, strength, tension

Judul: Shear Strength Parallel to Fibers and Bending Strength and Stiffness Perpendicular to Fibers of Betung Bamboo (Dendrocalamus asper)
Abstrak: Dendrocalamus asper (betung) merupakan bambu berdiameter besar dan sering digunakan untuk konstruksi. Penelitian ini bertujuan untuk menentukan nilai kapasitas dan kuat geser sejajar serat dan lentur tegak lurus serat bambu betung serta nilai estimasi 5% batas bawahnya. Ukuran contoh uji dan pengujian sifat mekanis mengacu pada BS ISO 22157:2019. Kadar air rata-rata bambu betung 14.50% untuk contoh uji geser sejajar serat dan 11.97% untuk contoh uji lentur tegak lurus serat. Kapasitas geser maksimum (Fult) berkisar 15518−66827 N. Kuat geser sejajar serat (fv) sebesar 5.38-14.01 N/mm². MOR (Modulus of rupture) dibedakan menjadi dua sesuai posisi kerusakannya yaitu Utara (U) atau Selatan (S) (fm,90 US) dan Timur (T) atau Barat (B)(fm,90 TB) . Rata-rata fm,90 US yang diperoleh sebesar 13.68 N/mm² sedangkan nilai rata-rata fm,90 TB yang diperoleh sebesar 7.95 N/mm². Nilai fm,90 US lebih tinggi karena kerusakan terjadi pada bagian dalam buluh bambu. Rata-rata modulus elastisitas lentur tegak lurus serat (Em,90) diperoleh sebesar 1798.35 N/mm². Nilai estimasi 5% batas bawah geser sejajar serat sebesar 5.53 N/mm² sedangkan untuk MOE dan MOR sebesar 305.53 dan 4.39 N/mm²., Dendrocalamus asper (betung) is large diameter bamboo, and commonly used for construction. This research aims to determine the values of shear strength parallel to fiber and bending strength and stiffness perpendicular to fiber of betung bamboo and its 5% exclusion limit value. The sample size and mechanical properties testing refers to BS ISO 22157:2019. The average moisture content of bamboo betung was 14.50% for shear parallel to grain samples and 11.97% for bending strength and stiffness perpendicular to the fiber. The maximum shear capacity (Fult) has a range between 15518-66827 N. The shear strength parallel to grain (fv ) has a range between 5.38-14.01 N/mm². The MOR (Modulus of Rupture) value obtained was categorized into two groups based on the failure position, which are North (U) or South (S) (fm,90 US ) and East (T) or West (B) (fm,90 TB). The maximum fm,90 US and fm,90 TB values obtained were 13.68 and 7.95 N/mm². fm,90 US was higher than fm,90 TB because fissure occured in bamboo internal surface. The average MOE (Modulus of Elasticity) (Em,90 ) was 1798.35 N/mm². Estimated value of 5% exclusion limit value of fv was 5.53 N/mm², while that of MOE and MOR were 305.53 and 4.39 N/mm².
Keyword: Dendocalamus asper, Moisture content, Shear strength, Estimated value, Flexural properties

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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