Judul: Perbandingan kualitas layanan pada protokol VOIP H.323 dan SIP
Abstrak: Voice over Internet Protocol (VoIP) adalab suatu teknologi yang dapat mentTiznsmisikan pesan sum melalui jaringan data (internet protocol). Rotokol VolP yang banyak digunakan saat hi adalah H.323 dm SIP. SIP dikembangkan oleh Internet Engineering Task Force's (ETF) yang dituangkan dalam RFC2543 dm H.323 dikembangkan oleh International Telecommzrnication Union (ITU-T). Perbedaan yang mendasar mtara kedua protokol tersebut adalah format data yang ditransmisikan, H.323 menggunakan format binary, sedangkan SIP menggunakan format text (ASCII).
Keyword: 

Judul: Autentikasi Berbasis LDAP Untuk Interkoneksi Server VoIP Menggunakan Codec G.722 dan GSM.
Abstrak: VoIP merupakan salah satu layanan telekomunikasi berbasis IP yang berkembang dengan cepat. VoIP memiliki beberapa protokol signaling yaitu H.323, SIP, dan IAX. QoS dapat mempengaruhi kualitas suara. Parameter QoS yang diukur yaitu delay, jitter, dan packet loss. Kualitas suara dapat diukur dengan menghitung nilai R factor. Dalam penelitian ini komunikasi VoIP dibangun dalam server yang sama dan antarserver. Penyimpanan data user pada VoIP dilakukan dengan melakukan integrasi dengan LDAP. Pengujian dilakukan dengan menganalisa QoS menggunakan codec yang sama dan codec yang berbeda. Hasil pengujian menunjukan codec GSM mendapat nilai QoS terbaik yaitu jitter 16.92 ms, delay 40.12 ms, dan packet loss 0.19% serta mendapat nilai R factor sebesar 92 dan pada codec G.722 mendapat nilai jitter 19.48 ms, delay 40.14 ms, dan packet loss 0.22 % serta mendapat nilai R factor sebesar 91.
Keyword: client, codec, interkoneksi, QoS, server, VoIP

Judul: Heterologous Expression Of Endo-Β-Xylanase From Bacillus Pumilus Strain Bcrs-01 In Escherichia Coli.
Abstrak: Xylanases are glycoside hydrolase family 11 which depolymerise xylan in the plant cell wall, the most excessive form of hemicellulose. Endo-β-xylanases (EC 3.2.1.8) are most important to breakdown β-1,4-glicoside bond of xylan to produce disaccaride xyloolygosaccaride (XOs) and xylose (monomer). Bovine rumen fluids have potential to obtain endo-β-xylanase produced of bacteria. The objectives of this study were to obtain xylanase producing bacteria and to express xynA gene encoding endo-β-xylanase from bacterium in Escherichia coli. Twenty nine isolate bacteria have been succesfully isolated from bovine rumen fluid in agar medium containing birchwood xylan. Isolate BCRS-01 bacterium was previously screened for the high production of xylanase. Based on 16S rRNA gene sequence analysis, BCRS-01 showed high similarity (99%) to Bacillus pumilus (accession number NR043241). The crude xylanase had optimal activity at 55oC, pH 7.0. Furthermore, the crude xylanase exhibited broad pH stability from 4.0 to 10.0 and remained more than 60% and 40% of its activity after incubation at pH 4.0 until 10.0, respectively for 60 min. It also showed a stability at temperature 25-50oC since it retained 80% and 50% of its activity when incubated at 50oC or 30 and 60 min, respectively. The xylanase activity was strongly inhibited by Ca2+ and Cu2+ at concentration 10 mM, and as little as 1 mM for Mn2+. Therefore, this xylanase has potentially used as additive feeds in animal feed industry. The DNA sequence xynA gene encoded endo-β-xylanase was amplified and cloned into the expression vector pET-15by under the control of T7 promoter. The recombinant protein had succesfully expressed in Escherichia coli BL21 (DE3) pLysS. A protein recombinant of approximately, 26.7 kDa was observed on the SDS-PAGE analysis. Crude extract of recombinant endo-β-xylanase demonstrated activity of enzyme at 56 U mL-1 using birchwood xylan as a substrate at 55oC for 10 min.
Keyword: Bacillus pumilus, bovine rumen fluid, endo-β-xylanase, heterologous expression.