PC computer is a flexible electronic device and can receive and process data quickly and accurately, and can also store data for a long time. There is a time when the PC hardware is damaged. So that it annoys the user. In connection with the problems that occur, the researchers aim to build an Expert System application to diagnose damage to PC computers using the Certainty Factor method by using Visual Studio 2010 applications and using Microsoft Access 2013 as a database. Applications that are built can be an alternative in knowing the type of damage and provide alternative solutions in handling damage to PC computer hardware.

Consumer purchasing patterns are a form of purchases made by consumers, whether someone or a lot of people to get the desired item by making a purchase transaction. One characteristic of the purchase pattern is the existence of acquiring something through exchanging money. This study aims to create an application that is used in determining consumer purchasing patterns by applying a priori algorithms and using Visual Basic 2010 as a tool for determining consumer purchase patterns. This application uses a priori algorithm calculation method where the sample consumer purchase data will be sorted and calculated by providing the value of the minium support and configuration parameters and based on the results of confidence the largest number of conclusions such as: can be used as information for determining sales, the application of a priori algorithms can provide information pattern combination item set from consumer purchase data that is with support above 15% and confidence above 50% on item set.

One technology that can be applied in hydroponic farming systems is sensing. Sensors used in this research are pH, electrical conductivity, water level, and temperature sensor. The First Come First Served (FCFS) algorithm is used to help scheduling data plotting. In order to be serviced by the processor, data entities in the queue must wait until all previous processes have been completed. The final test results show that the average success of the system succeeded in activating the actuator to operate the feeding was 92.5% and operating the heater to warm the water temperature was 83.33% for the 720-hour testing period. All sensing data also successfully plotted in graphical form for each of the results of sensing the pH value, water temperature, and electrical conductivity in water.

Lately more IoT use of devices both used at home, disaster prone, hospitals, highways and government agencies and many other places that use IoT device for data acquisition in realtime therefore the authors want to examine the security of IoT devices that is increasingly being used by utilizing OTP codes sent by smartphone devices or GSM modules to keep IOT devices from people who want to exploit the IoT device.

The development of technology has been very significant, not only in the fields of information, industry, education, but in agriculture. Therefore technological sophistication is also utilized by corn farmers to obtain information about corn crops. Corn is included in plantation commodities in Indonesia. However, in corn cultivation there are various problems associated with the disease that is likely to attack the plant. Therefore, the authors designed the expert system of corn disease diagnosis using certainty method. This system will analyze based on symptoms - symptoms that are in the input by the user so that in obtaining a result of disease identification on corn in the name of the disease, the cause of the disease, the percentage value and how to handle it. This expert system is developed by using the visual basic application and Microsoft Access database with Certainty Factor method to measure the value of certainty of a hypothesis against a fact.