Judul: Real-time And In Situ Internet of Things Integrated Microalgae  Growth Monitoring System Based On Optical Sensor
Abstrak: Pemantauan pertumbuhan mikroalga yang dilakukan saat ini masih menggunakan metode yang kurang praktis, yaitu melihat warna kultur atau pengukuran kepadatan sel menggunakan spektrofotometer secara manual. Pembuatan sistem pemantauan pertumbuhan mikroalga terintegrasi Internet of Things ini dapat membantu pengguna untuk memantau pertumbuhan mikroalga dengan lebih tepat dan cepat. Absorbansi (kepadatan sel) dapat diukur untuk kemudian diolah menjadi informasi pertumbuhan mikroalga dengan memanfaatkan fenomena gelombang evanescent yang terjadi pada serat optik,. Pada penelitian ini, Spirulina plantesis dipilih sebagai objek penelitian karena waktu pertumbuhan yang relatif singkat. Hasil pengambilan data sinyal sensor untuk dibandingkan dengan data acuan dengan menggunakan spektrofotometer sehingga menghasilkan persamaan yang dapat digunakan untuk merancang alat untuk mengukur absorbansi kultur mikroalga S. plantesis. Hasil uji coba menghasilkan nilai R-squared sebesar 0.878. Selain diukur dan disimpan pada penyimpanan lokal, data pengukuran juga dikirimkan ke server untuk diolah menjadi informasi yang ditampilkan pada antarmuka web dashboard., Microalgae growth monitoring currently carried out still use methods that have low accuracy and efficiency such as looking at the color of culture or measure cell density using a spectrophotometer manually. The creation of an Internet of Things integrated microalgae growth monitoring system can help farmers to monitor microalgae growth more precisely and quickly. By utilizing the phenomenon of evanescent waves that occur in optical fibers, absorbance (cell density) can be measured and then processed into microalgae growth information. In this study, Spirulina plantesis was chosen as the research object because of the relatively fast growth time. The results of the sensor signal retrieval to be compared with reference data using a spectrophotometer to produce an equation that can be used as a tool to measure the absorbance of S. plantesis microalgae culture. The trial results produce a R-squared value of 0.878. In addition to being measured and stored in local storage, measurement data is also sent to the server to be processed into information that is displayed on the web dashboard interface.
Keyword: absorbansi, evanescent, Internet of Things, mikroalga

Judul: Design of Microalgae Growth Monitoring System Based on IoT
Abstrak: Mikroalga adalah mikroorganisme fotosintesik yang memanfaatkan sinar matahari dan karbondioksida untuk menghasilkan biomassa. Mikroalga memiliki tingkat efisiensi yang lebih tinggi dalam penggunaan air, karbondioksida, dan nutrisi lainnya bila dibandingkan tanaman tingkat tinggi. Salah satu mikroalga yang menghasilkan banyak minyak adalah Chlorella sp. Mikroalga jenis Chlorella memiliki tingkat reproduksi tinggi, setiap sel Chlorella dapat berkembang menjadi 10000 sel dalam waktu 24 jam. Kondisi lingkungan dalam sistem budidaya mikroalga harus dioptimalkan dan dikendalikan untuk mendapatkan hasil produksi yang maksimal. Tujuan dari penelitian ini adalah untuk merancang alat pemantau kepadatan mikroalga Chlorella sp. dan dapat dilihat pertumbuhannya secara real-time menggunakan sensor turbidity (TSD 10), mikrokontroler Arduino, dan modul wifi ESP8266. Tahap penelitian ini dimulai dengan perancangan alat monitoring yang meliputi perancangan sistem elektronika dan perancangan perangkat lunak, serta dilakukan perancangan media kultur mikroalga. Kemudian dilakukan pengujian alat yang meliputi uji sensor dan uji laboratorium. Setelah itu dilakukan analisis data dan didapatkan persamaan y = -1.633x + 1421.3, variabel y merupakan nilai kepadatan mikroalga dan x adalah nilai ADC sensor. Berdasarkan persamaan tersebut didapat nilai R2 sebesar 0.9921. Setelah kalibrasi sensor dilakukan proses validasi yang menghasilkan R2 sebesar 0.9962. Berdasarkan uji tersebut didapat kan error rata-rata pada sensor adalah 3.91%, dengan selisih terbesar 7.27%., Microalgae are photosynthetic microorganisms that utilize sunlight and carbon dioxide to produce biomass. Microalgae have a higher efficiency level in using water, carbon dioxide, and other nutrients than higher plants. One of the microalgae that produce much oil is Chlorella sp. Chlorella have a high reproductive rate, each cell Chlorella can develop into 10000 cells within 24 hours. Environmental conditions in the microalgae cultivation system must be optimized and controlled to obtain maximum production results. The purpose of this study was to design a density monitoring tool for microalgae Chlorella sp. and can see its growth in real-time using the sensor turbidity (TSD 10), the Arduino microcontroller, and the ESP8266 wifi module. This research phase begins with the design of a monitoring tool which includes the design of electronic systems and software design, as well as the design of microalgae culture media. Then testing the equipment which includes sensor tests and laboratory tests. After that, data analysis was carried out and the equation y = -1.633x + 1421.3 was obtained, which y is the microalgae density value and x is the ADC sensor value. Based on this equation, the R2 value is 0.9921. After calibration of the sensor, a validation process was carried out which resulted in an R2 of 0.9962. Based on this test, the average error on the sensor is 3.91%, with the largest difference reaching 7.27%.
Keyword: Chlorella sp, density, microalgae, monitoring system

Judul: Truncated Stop Loss as a Optimal Solution of Reinsurance Agreement in One-Period Model
Abstrak: Reinsurance is one of risk management efforts of an insurance company, which is called the cedent. Similar with insurance, reinsurance constitutes the cedent to pay the premium. We consider one-period reinsurance model and derive a rule which minimizes the ruin probability of the cedent for a fixed reinsurance premium. Therefore, it is needed to construct an optimal reinsurance agreement for the cedent. The premium is calculated according to four different principles, i.e. economic, generalized zero-utility, Esscher, and mean-variance principles. Stop loss is a reinsurance contract which protect the insurance company for losses that exceed a certain amount. The result of this research shows that a truncated stop loss is an optimal agreement in the class of all reinsurance contracts with various premiums calculated using above mentioned principles.
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