No abstract

The critical environmental issues of the Indonesian automotive market growth are the increase in air pollution. Vehicle exhaust emission can cause significant problems for the human health and the environment. Therefore, vehicle emission control is indispensable to mitigate the environmental problem. One of the most widely used methods to reduce automotive emission is utilization of catalytic converter in exhaust system. In fact, the catalyst performance in the reduction of noxious gases depends on its material and geometric design. This study aims to evaluate the effect of geometric parameter on the performance of motorcycle catalytic converters. In this experimental study, the catalytic converter made of brass foil plate is mounted on motorcycle muffler. The effectiveness of three catalyst geometry models namely flat perforated plate, folded perforated plate and rolled brass sheet, will be evaluated in relation to the reduction of hydrocarbon (HC) and carbon monoxide (CO) content. HC and CO emission levels are measured by four gas analyzers. The results show that the geometric parameter has a significant effect on HC and CO’s composition in the exhaust gas. For idle speed test, the second geometry model of catalyst presents the best performance in reduction of Hydrocarbon and CO2 concentration.

AbstrakPenelitian ini memiliki tujuan untuk mengetahui hubungan antara karakter disiplin dengan hasil belajar sosiologi siswa di SMA Negeri 4 Padang. Jenis penelitian ini tergolong penelitian ex post facto.Subjek dalam penelitian ini adalah siswa SMA Negeri 4 Padang, teknik pengambilan sampel adalah proportional random sampling, dengan jumlah sampel 78 siswa. Variabel yang diteliti yaitu: (1) variabel bebas: karakter disiplin (X), 2) variabel terikat: hasil belajar siswa (Y). Pengumpulan data pada penelitian ini menggunakan metode angket dengan skala likert. Keabsahan data menggunakan uji validitas dan reliabilitas. Teknik analisis data untuk uji hipotesis menggunakan rumus korelasi product moment. Hasil uji hipotesis dengan rumus korelasi product moment diperoleh nilai rhitung 1,402 > rtabel 0.222, hal ini berarti terdapat hubungan antara karakter disiplin dengan hasil belajar siswa. Pada penelitian ini terdapat 5 indikator. Pertama, indikator ketaatan terhadap tata tertib di sekolah memiliki rhitung 1,007 dengan rtabel 0,222. Kedua, indikator ketaatan terhadap kegiatan belajar di sekolah, pada indikator ini nilai rhitung 1.185 dan nilai rtabel 0,222. Ketiga, indikator ketaatan dalam mengerjakan tugas-tugas pelajaran, memiliki nilai rtabel 1,089 dan rhitung 0,222. Keempat, indikator mengucapkan salam. Memiliki nilai rhitung 0,872 dan rtabel 0,222. Kelima, indikator berdoa ketika berktivitas. Nilai rhitung 1,405 dengan rtabel 0,222. Hasil penelitian sesuai dengan pendapat teori karakter dari Lickona yang menyatakan bahwa karakter berkaitan dengan konsep moral, sikap moral dan perilaku moral, karakter yang dibelajarkan dengan baik pada proses pembelajaran akan memperlihatkan munculnya pengetahuan tentang kebaikan, keinginan untuk berbuat baik dan melakukan perbuatan baik, sehingga hasil belajar sebagai output dari proses pembelajaran akan berhasil baik. AbstractThis study have a purpose to find out the relationship between the character of discipline with sociology learning outcomes of students in SMA Negeri 4 Padang. This type of research is classified as ex post facto research. The subjects in this study were high school students of Padang 4 Padang. The research sample was taken by stratified random sampling with a total sample of 78 students. This study uses two variables, namely: (1) independent variable: discipline character (X), 2) dependent variable: student learning outcomes (Y). Data collection in this study used a questionnaire with a linkert scale. Data validity uses validity and reliability tests. The data analysis technique used is descriptive analysis to calculate the mean, median, mode, and standard deviation values. Data analysis for hypothesis testing uses the product moment correlation formula and to find out the percentage of the degree of influence of the variable X on the variable Y used the coefficient of determination. Hypothesis test results with the product moment correlation formula obtained rcount value of 1.402> rtable 0.222, this means there is a relationship between the character of d...