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Djoko Suprijanto
Combinatorial Mathematics Research Group Faculty of Mathematics and Natural Sciences Institut Teknologi Bandung
Energy Engineering Mathematics

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New Extremal Self-dual Codes of Length 36 Djoko Suprijanto; Bagus Ilman
Jurnal Matematika & Sains Vol 15, No 3 (2010)
Publisher : Institut Teknologi Bandung

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Abstract

A paper of Conway and Sloane (1990) gives the putative weight enumerators of extremal self-dual codes for length n £ 64 and n = 72. The construction of such codes with putative weight enumerator has been one of the fundamental problems in Coding Theory. In this paper, we construct new extremal binary self-dual codes of length 36. We show that there are at least 17 inequivalent extremal binary self-dual codes of parameter  [36, 18, 8]. Our invention upgrades the previous known result provided by Conway and Sloane (1990), Harada (1999), and Kim (2001).
EFFECT OF POST HEAT TEMPERATURE TO HARDNESS AND MACROSTRUCTURE IN WELDED STELL ST 37 - Subardi; Djoko Suprijanto; Roza Lyndu R. Mahendra
TRAKSI Vol 9, No 1 (2009): TRAKSI
Publisher : Universitas Muhammadiyah Semarang

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (138.798 KB) | DOI: 10.26714/traksi.9.1.2009.%p

Abstract

The present study aims to investigate the effect of post heat temperature of hardness andmacrostructure on the result steel welded St 37. Welded process with SMAW (Shelded Metal ArcWelding) and AC-DC current. Plate steel ST 37 welded of longitudinal, than heat treatment withtemperature various: 300°C, 400°C dan 500°C.Highest rate hardness 157,83 kg/mm2 on temperature treatment spesiment 500o cause haveferit grain boundary structure more and homogen so properties more hardness. The lows bendingstrength 43,51 kg/mm2 on raw material, cause have ferit structure and perlit so more soft properties.The micostuctrure welded area arround; ferit graind boundary, ferit widmanstatten, ferit acicularand perlit.
PENGARUH DIAMETER PENGEROLAN DINGIN TERHADAP KEKUATAN BENDING BAJA KARBON RENDAH Djoko Suprijanto
TRAKSI Vol 11, No 2 (2011): TRAKSI
Publisher : Universitas Muhammadiyah Semarang

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (12170.975 KB) | DOI: 10.26714/traksi.11.2.2011.%p

Abstract

Baja St 41 merupakan baja karbon rendah yang mengandung karbon dibawah 0,30% banyak diaplikasikan untuk konstruksi umum. Pembetukan benda dengan pengerolan banyak dilakukan untuk pembuatan bejana maupun konstruksi penguatan dengan plat baja .Pada penelitian ini dilakukan proses pengerolan dingin, baja AISI 1015 setebal 7,65 mm dengan radius: 500, 1000, 2000 dan 3000 mm. Pengujian yang dilakukan adalah uji komposisi kimia, uji kekerasan uji struktur mikro , dan uji kekuatan bending dengan arah berlawanan dari arah pengerolan. Dari hasil pengujian tersebut dapat disimpulkan bahwa pengerolan akan meningkatkan kekuatan bending sampai pada ukuran tertentu. Setelah Iewat batas tertentu maka bahan akan luluh sehingga menurunkan kekerasan serta kekuatan bendingnya.Kata kunci: Baja St 41, Rolling, Ferit, Kekuatan Bending
Co-Authors - Subardi Bagus Ilman Roza Lyndu R. Mahendra