Geological layout contributes Indonesia in becoming one of the most dangerous countries with natural disasters. The eruption of volcano is one of the most dangerous natural disasters in the world. However, our efforts in disaster mitigation is not enough, especially in developing new mitigation technology. We already know that the Wireless Sensor Network (WSN) technology can be an alternative electronic communications technology that can be used in disaster mitigation because the WSN has the ability to communicate using Radio Frequency (RF) and can be connected to a digital or analog sensor. Then, the Computer Personal Unit (CPU) in WSN is used to run the protocols, such as hop-to-hop protocols. Later, we can build a monitoring system that have small size, energy saving, low cost, and capable to show realtime monitoring. The problem that must be solved in this research is how to make a design communication based on WSN that have accordance with the extreme conditions like at Kelud Volcano. Currently, with utilization of temperature sensor and gas sensor and delivery schedule of data packets as parameters, we want to find how to test the design with minimal electricity supply. Intisari-Letak geologis menyebabkan Indonesia menjadi salah satu negara yang rentan dengan bencana alam. yang salah satunya adalah bencana erupsi gunung api. Hal ini berbanding terbalik dengan upaya mitigasi bencana yang belum banyak dilakukan dan dikembangkan teknologinya di Indonesia. Di sisi lain, kita ketahui bahwa teknologi Wireless Sensor Network (WSN) bisa menjadi salah satu alternatif teknologi komunikasi elektronika yang menjanjikan karena WSN sudah memiliki kemampuan berkomunikasi menggunakan Radio Frequency (RF) yang dapat dihubungkan dengan sebuah digital sensor. Kemudian, Computer Personal Unit (CPU) digunakan untuk menjalankan protokol-protokol, misalnya hop-to-hop protocols, sehingga nantinya dapat dibuat sebuah sistem monitoring yang memiliki ukuran yang kecil, hemat energi, berbiaya rendah, serta mampu melakukan real-time monitoring. Permasalahan disini adalah bagaimana membuat desain komunikasi dengan berbasis WSN yang sesuai dengan kondisi yang ekstrem di Gunung Kelud saat ini, dengan memanfaatkan sensor suhu dan sensor gas serta memanfaatkan penjadwalan pengiriman paket data sebagai parameter pengujian dengan kondisi tempat pengujian yang minim dengan pasokan tenaga listrik.

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The characteristics of assessment instrument are important to obtain representative information about students' knowledge and abilities in education. The representation ability is fundamental ability to solve problems in learning Physics. This study aims to determine the characteristics of assessment instrument for the representation abilities of diagram and verbal in high school Physics. The assessment instrument consists of two test sets with four category response according to Partial Credit Model (PCM). The subject of the research was a sample of 305 students of XI IPA class from high schools in Yogyakarta. The subject was selected through purposive sampling based on the result of national high school examination year 2016/2017. The research data were analyzed with item response theory (IRT) according to PCM. Based on the result estimation of parameter and student ability, that (1) item difficulty index ranged from-1.02 to +1.17, which satisfies the criteria of good test items; (2) all test items fit with the PCM model; (3) the information function is 10 and SEM is 0.21; and (4) the ability estimation ranges from-2.08 to +2.10, indicating that students' abilities are varied. The assessment instrument fits with PCM model and can be categorized as good, meaning that it can be used to measure diagram and verbal representation abilities of high school students in Physics.