Judul: Analysis of Urban Heat Island Phenomenon in Bogor City Using Cloud Computing Technology
Abstrak: Fenomena Urban Heat Island (UHI) merupakan fenomena yang biasa terjadi di kota-kota besar karena tingginya kepadatan lahan terbangun. UHI dapat diidentifikasi menggunakan data citra satelit menggunakan teknik penginderaan jauh. Seiring berjalannya waktu, teknik penginderaan jauh dapat dilakukan melalui internet tanpa perlu mengunduh data terlebih dahulu dengan menggunakan teknologi cloud computing atau komputasi awan. Penelitian ini menggunakan Google Earth Engine sebagai platform komputasi awan untuk keperluan analisis data citra satelit. Data yang digunakan adalah Landsat 8 OLI/TIRS path 112 row 64 & 65 dan peta batas administrasi Kota Bogor. Penelitian ini mengidentifikasi fenomena UHI dengan mengestimasi suhu permukaan dan suhu udara, mengestimasi indeks spektral, dan mengestimasi Urban Thermal Field Variance Index (UTFVI). Hasil yang diperoleh menunjukkan bahwa sebaran suhu di Kota Bogor memiliki nilai yang tinggi di pusat Kota Bogor tepatnya di Kecamatan Bogor Tengah. Hal ini diperkuat dengan hasil UTFVI dimana Kecamatan Bogor Tengah memiliki nilai indeks terburuk. Kedua hasil ini dapat menggambarkan fenomena UHI di Kota Bogor. Nilai indeks spektral Normalized Difference Built-up Index (NDBI) memiliki pengaruh signifikan terhadap nilai suhu permukaan di Kota Bogor dengan nilai koefisien determinasi yang diperoleh adalah 0,769, 0,725, dan 0,782. NDBI dapat dijadikan acuan atau indikator fenomena UHI., The Urban Heat Island (UHI) phenomenon is a common phenomenon in big cities due to high density of built-up area. UHI can be identified using satellite image data with remote sensing techniques. As time goes by, remote sensing techniques can be done via internet without downloading the data first by using cloud computing technology. This study uses Google Earth Engine as a cloud computing platform for analyzing satellite image data. The data used are Landsat 8 OLI/TIRS path 112 row 64 & 65 and administrative boundary map of Bogor City. This study identified UHI phenomena by estimating the surface temperature and air temperature, estimating the spectral indices, and estimating Urban Thermal Field Variance Index (UTFVI). The results show that the temperature distribution in Bogor City has a high value in the center of Bogor City, precisely in Central Bogor District. This is reinforced by the UTFVI results where Central Bogor District has the worst index value. These two results can describe the UHI phenomenon in Bogor City. The Normalized Difference Built-up Index (NDBI) value has a significant effect on the surface temperature value in Bogor City. The coefficient of determination values obtained are 0.769, 0.725, and 0.782. NDBI can be used as a reference or indicator of the UHI phenomenon.
Keyword: Google Earth Engine, land surface temperature, spectral indices, surface energy balance

Judul: Fenomena Urban Heat Island dan Hubungannya dengan Konsentrasi Ozon Permukaan (O₃) di Kota Bogor
Abstrak: Kota Bogor termasuk kota besar yang mengalami peningkatan pembangunan cukup signifikan. Penelitian ini bertujuan mengidentifikasi fenomena UHI dan konsentrasi ozon permukaan di Kota Bogor selama tahun 2013 hingga 2022. Sumber data berasal dari citra Landsat 8 dan 9 serta Aura-OMI yang diolah menjadi data penyebaran tutupan lahan, suhu permukaan, dan konsentrasi ozon permukaan. Penelitian menunjukkan pertambahan luas lahan terbangun sebesar 14,780 km² sehingga membuat persentase luas lahan terbangun naik dari 54,176 % menjadi 67,315 % pada tahun 2022. Suhu permukaan rata-rata di Kota Bogor naik sebesar 2,960 °C, suhu tertinggi serta terendah juga naik sebesar 2,704 °C dan 1,765 °C pada tahun 2022. Konsentrasi ozon permukaan yang didapat dari tahun 2013 hingga 2022 naik sebesar 0,440 µg/m³. Penyebaran O₃ tertinggi berada di wilayah barat dan utara Kota Bogor, sedangkan terendah di timur dan selatan Kota Bogor. Nilai korelasi antara luas lahan terbangun dan suhu permukaan sebesar 0,6478 atau berhubungan kuat, antara konsentrasi ozon dan suhu permukaan senilai 0,4416 atau berhubungan sedang, dan antara luas lahan terbangun dengan konsentrasi ozon adalah 0,1135 atau berhubungan sangat lemah., Bogor City is a big city that has experienced a significant increase in development. This study aims to identify the phenomenon of UHI and surface ozone concentrations in Bogor City during 2013 to 2022. The data source comes from Landsat 8 and 9 imagery as well as Aura-OMI which are processed into data on land cover distribution, surface temperature, and surface ozone concentration. Research shows an increase in the area of built-up land by 14,780 km², making the percentage of built-up land area increase from 54,176% to 67,315% in 2022. The average surface temperature in Bogor City rose by 2,960 °C, the highest and lowest temperatures also rose by 2,704 °C and 1,765 °C in 2022. Surface ozone concentrations obtained from 2013 to 2022 rose by 0,440 μg/m³. The highest spread of O₃ is in the western and northern regions of Bogor City, while the lowest is in the east and south of Bogor City. The correlation value between built-up land area and surface temperature is 0,6478 or strongly related, between ozone concentration and surface temperature worth 0,4416 or moderately related, and between built-up land area with ozone concentration is 0,1135 or very weakly related.
Keyword: built-up land, land cover, surface ozon, surface temperature, UHI

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.
Keyword: