Plastic waste can cause serious environmental problems. This can be overcome by various efforts; one of them is by replacing the use of conventional plastic with biodegradable plastic. Biodegradable plastic can be produced from tubers containing starch. The purpose of this study was to explain the suitability of two tuber species with typical protein quality and different starch structures. Starch was obtained from suweg tuber (Amorphophallus campanulatus) and ganyong (Canna edulis Ker). The material invested was obtained by dissolving 4 grams of each starch, each of which was dissolved with distilled water then added with various weight carrageenan. The tensile strength of biodegradable plastic was tested using tensile testing machines, biodegradation of soaked plastics using EM4 (Effective Microorganism) with reduced weight measurements, and Fourier Transform Infra-Red (FTIR) was used to identify the structure of compounds contained in biodegradable plastics. The tensile strength test results of biodegradable plastic from ganyong/canna tubers were 3.35 MPa with elongation of 13.51%, while the plastic from suweg tubers of 2.45 MPa with elongation was 13.68% on the addition of 5% carrageenan, respectively. Plastic degradation testing obtained plastic decomposition up to 100% in 37 days for ganyong and 34 days for suweg, respectively. It showed that the plastics was easily degraded. Identified by FTIR showed chemical structures of OH phenolic alcohols, C = O carbonyls, CO esters, NH amides and amines, and C≡C alkyne.

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The purpose of this study was to find a model system of power generation by using solar-cells for house. The research was a realization of concern in overcoming the electricity energy crisis. Solar panels, inverters, batteries, and solar charge controllers were used to support on this study. Polycrystalline solar panels with 4 × 50Wp power were chosen to generate energy. The output voltage ranges from 14.8 to 17.5 V DC (direct current) per panel with a capacity of 2 × 70 Ah. Battery capacity of 24 volts was connected in series with an inverter of 1000 watts. The result of the study showed the voltage output of the solar panels was at maximum average of 30.2 V. The distribution of batteries charging used a solar charger controller at a voltage of 24.5 volt DC. The measurement of voltage resulted at the inverter output from 24 volt DC to converse of 220 volt AC (alternating current) without load. Voltage conditions as outputs of solar panels reach maximum voltage during the day from 10:00 am to 1:00 pm Western Indonesia Time (WIB) and it begin down until 6:00 pm. The design greatly influenced the performance of solar power plants.

Design of a helmet mold project with an injection molding process to provide a simulated picture of a product. The helmet design that will be realized is made of polymer material with an injection molding machine as the main tool. The use of the machine so that time efficiency becomes faster, the mold designed is only in the form of a core and cavity. The software used is Autodesk Inventor 2017 with HDPE (high density polyethylene) material. Making a futuristic helmet product design requires a design style that offers a modern, unique and unusual appearance. The purpose of this design is to be able to design project helmets that are more modern than before. The method used for the design of this project helmet is a simulation of fill analysis, fill time, confidence of fill, quality prediction to show the level of quality of the injection results. The test results of the fill time takes 11.67 seconds, the confidence of the filling capability is 100% filled, and the quality prediction of the product quality is very good 82.1%.

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