Judul: Mapping of Mangrove Distribution and Density in Mojo Village, Pemalang Regency
Abstrak: Hutan mangrove merupakan sebuah ekosistem yang memiliki banyak kegunaan seperti pelindung garis pantai, habitat berbagai biota, dan sumber ekonomi nelayan. Pemanfaatan teknologi penginderaan jauh seperti citra satelit untuk memantau kondisi mangrove menjadi alternatif di tengah berkembangnya teknologi saat ini. Penelitian ini bertujuan untuk mengetahui sebaran dan kerapatan mangrove serta tingkat keakuratan Citra Sentinel-2A dalam memetakan hutan mangrove di Desa Mojo, Kabupaten Pemalang. Metode yang digunakan dalam penelitian ini yaitu menduga tingkat kerapatan mangrove dengan algoritma Normalized Difference Vegetation Index (NDVI) dan survei lapang dengan hemispherical photography. Komposit band yang digunakan guna mendapatkan reflektan vegetasi mangrove dengan maksimal yaitu gabungan band 8-11-4 dari Citra Sentinel-2A. Penelitian ini menghasilkan beberapa kelas objek seperti pemukiman, vegetasi mangrove, dan vegetasi lain menggunakan klasifikasi supervised metode maximum likelihood. Penelitian ini juga menghasilkan tiga kelas kerapatan mangrove yaitu kelas rapat, sedang, dan jarang dengan luas masing-masing sebesar 54,86 Ha, 16,78 Ha, dan 84,68 Ha. Total luas hutan mangrove di Desa Mojo yaitu 168,68 Ha yang tersebar di wilayah utara desa. Dalam penelitian ini, nilai akurasi Citra Sentinel-2A yaitu 80% menggunakan metode confussion matrix., Mangrove forests are an ecosystem that has many uses, such protecting coastlines, habitat for various biota, and an economic source for fishermen. The use of remote sensing technology such as satellite imagery to monitor mangrove conditions is an alternative amidst current technological developments. This research aims to determine the distribution and density of mangroves as well as the level of accuracy of Sentinel-2A imagery in mapping mangrove forests in Mojo Village, Pemalang Regency. The method used in this research was estimating the level of mangrove density using the Normalized Difference Vegetation Index (NDVI) algorithm and field surveys using hemispherical photography. The composite band used to obtain maximum reflectance of mangrove vegetation was a combination of bands 8-11-4 from Sentinel-2A imagery. This research produced several classes of objects such as settlements, mangrove vegetation and other vegetation using the supervised classification method of maximum likelihood. This research also produced three classes of mangrove density, namely dense, medium and sparse classes with areas of 54.86 Ha, 16.78 Ha and 84.68 Ha respectively. The total area of mangrove forests in Mojo Village is 168.68 Ha spread across the northern area of the village. In this research, the accuracy value of the Sentinel-2A imagery was 80% using the confusion matrix method.
Keyword: Mangrove, NDVI, Sentinel-2A, Hemispherical Photography, Desa Mojo

Judul: Mapping the Extent and Density of Mangroves Using Sentinel 2A Image Classification in CMC Tiga Warna
Abstrak: Mangrove adalah tumbuhan pantai yang tumbuh di daerah pasang surut dan pantai berlumpur. Berfungsi sebagai zona penyangga dan melindungi garis pantai dari kerusakan akibat abrasi. Teknologi penginderaan jauh sangat tepat digunakan untuk pemantauan ekosistem mangrove di CMC Tiga Warna yang mengalami peningkatan belakangan ini. Tujuan dari penelitian ini adalah untuk mengetahui perubahan luasan dan kerapatan mangrove menggunakan Citra Sentinel-2A. Klasifikasi kerapatan citra menggunakan metode Normalized Difference Vegetation Index (NDVI) dan dilakukan pengambilan data lapang sebanyak 55 titik menggunakan metode Hemispherical photography. Hasil penelitian menunjukkan 3 kelas kerapatan mangrove yaitu kelas rapat dengan luasan sebesar 46,10 ha, kelas sedang 0,75 ha, dan kelas jarang 0,82 ha pada tahun 2015. Tahun 2023 luas mangrove untuk kelas rapat, sedang dan jarang masing-masing adalah 62,27 ha, 1,01 ha, dan 0,59 ha. Luas total hutan mangrove tahun 2015 sebesar 47,67 ha dan tahun 2023 sebesar 63,87 ha. Kerapatan mangrove di CMC Tiga Warna mengalami peningkatan selama 8 tahun terakhir pada kelas rapat dan sedang. Hal ini mengindikasikan program pengelolaan mangrove di lokasi ini dapat dikatakan berhasil., Mangroves are coastal plants that grow in tidal and muddy areas. They function as buffer zones and protect coastlines from abrasion damage. Remote sensing technology is highly suitable for monitoring the mangrove ecosystem in CMC Tiga Warna, which has experienced recent growth. The objective of this study is to determine changes in the extent and density of mangroves using Sentinel-2A imagery. The classification of density was conducted using the Normalized Difference Vegetation Index (NDVI) method, and field data collection is conducted at 55 points using the Hemispherical Photography. The research results show that there are 3 density classes of mangroves, namely dense class with an area of 46.10 ha, moderate class 0.75 ha, and sparse class 0.82 ha in 2015. In 2023, the area of mangroves for dense, moderate, and sparse classes respectively are 62.27 ha, 1.01 ha, and 0.59 ha. The total area of mangrove density in 2015 was 47.67 ha, while in 2023 it reached 63.87 ha. The mangrove density in CMC Tiga Warna has increased by 16.2 ha over the past 8 years for the dense and moderate classes. It indicates that the development program of mangrove in this location can be considered successful.
Keyword: CMC Tiga Warna, Kerapatan, Mangrove, NDVI, Sentinel 2A Satelit

Judul: Bifurkasi Hopf pada Model Siklus Bisnis Kaldor Kalecki tanpa dan dengan Waktu Tunda
Abstrak: Business cycle model is one of dynamical system models in economic. One of the business cycles model is Kaldor-Kalecki model. Kaldor-Kalecki business cycle model that is written in delayed defferential equations, is a business cycle model that involves gross product and capital stock of a company. In this paper Kaldor-Kalecki business cycle model is analyzed using both nondelay and delay in time of capital stock. By Taylor expansion for the time delayed model, an analysis of stability around the fixed points has been done. Furthermore, by using Hopf bifurcation theorem, it can be shown that there exists periodic orbits and limit cycle. In the nondelayed model, changing the parameter of goods market could lead to the occurrence of Hopf bifurcation and the existence of limit cycle. Similarly, for the delayed model, it has been shown that changing the time delay parameter may result in the occurrence of Hopf bifurcation and limit cycle.
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