Judul: Estimating of Coffee Export Volume Model with Principal Components Regression
Abstrak: Volume ekspor kopi dapat dipandang sebagai suatu data deret waktu dan sebagai suatu data sebab akibat. Sebagai suatu data deret waktu, volume ekspor dapat dimodelkan berdasarkan pengamatan- pengamatan sebelumnya menggunakan model ARIMA. Sedangkan sebagai data sebab akibat ada dua pendekatan yang dapat digunakan yaitu model volume ekspor dipengaruhi oleh waktu (regresi linear sederhana) dan volume ekspor yang dipengaruhi oleh produksi domestik, luas areal tanaman kopi, harga, nilai tukar rupiah terhadap $ US, konsumsi dunia, dan produksi dunia (regresi berganda). Penelitian ini bertujuan untuk menduga model volume ekspor kopi menggunakan analisis deret waktu (ARIMA), regresi linear sederhana dan regresi komponen utama untuk menghindari pengaruh multikolinearitas antar peubah bebas pada regresi berganda, kemudian membandingkan ketiganya untuk memperoleh model terbaik dan digunakan untuk meramal volume ekspor kopi. Model volume ekspor kopi diduga dengan regresi komponen utama. Meskipun nilai MSE dan lebar selang yang dimiliki oleh model ini lebih besar daripada regresi linear sederhana, akan tetapi asumsi kebebasan sisaan model regresi komponen utama cenderung terpenuhi
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Judul: Faktor-faktor yang Mempengaruhi Volume Ekspor Kopi Indonesia ke Pasar Internasional
Abstrak: Agriculture is a sector that plays a vital role in economic activity in Indonesia. The contribution of agriculture to Gross Domestic Product was around 12.72 percent in 2019, which is the third-largest proportion after the Manufacturing Industry and Wholesale and Retail Trade at 19.70 percent and Car and Bicycle Repair Motor by 13.01 percent (BPS, 2020). As one of the largest coffee exporters in the world, Indonesia has significant destination countries in exporting coffee beans. The ten countries that are the main markets for Indonesian coffee beans are the United States, Germany, Japan, Italy, Malaysia, England, Egypt, Belgium, Algeria, and India. From year to year, Indonesian coffee exports continue to fluctuate. This becomes a question, what factors affect Indonesian coffee exports to the international market. This study aims to identify the factors that influence changes in the volume of Indonesian coffee exports to major importing countries (the United States, Germany, Japan, Italy, Malaysia, England, Egypt, Belgium, Algeria, and India). The data used in this study is panel data from 2000 to 2019. The method used in this study is Panel Data Regression with a Fixed Effect Model (FEM) approach to determine whether the independent variables in this study have a significant effect on coffee exports and how the relationship between the dependent and independent variables partially. Based on the data processing carried out, it was found that Gross Domestic Product (GDP), exchange rate, and retail prices of importing countries significantly influence in a negative relationship the volume of Indonesian coffee exports to export destination countries. The Great depression in 2008 has a positive and significant relationship with the dependent variable. Meanwhile, other variables, namely the volume of production, and variable of government intervention in 2012, did not significantly affect the volume of Indonesian coffee exports.
Keyword: coffee, export volume, international market

Judul: Hybrid solar cells of ZnO nanoparticles/chlorophyll was modified metal ions (Zn2+ and Cu2+ )
Abstrak: Zinc Oxide (ZnO) is a n-type semiconductor with a wide the energy band (Band Gap) is 3.37 eV at room temperature and 3.34 eV at low temperature with a large exiton binding energy is 60 meV. ZnO has been synthesized by hydrothermal method, resulting in a decrease in particle size over the duration of the hydrothermal changes. Crystallographic structure of ZnO were characterized using XRD, has shown the characteristic pattern of a hexagonal wurtzite structure, the crystallite size increases to changes in particle size. Changes in particle size has also led to a change in the absorption peak of ZnO as has been demonstrated posted under test using the optical properties of UV-Vis spectrophotometer. Changes of this uptake has also led to changes in the energy band gap, which increases its band gap energy of the particle size. In electronic applications, especially in solar cells. Chlorophyll is considered less effective, because of their very nature are easily degraded as a result of several reactions which are acid, lighting and temperature. The results of the stability test using a halogen lamp 34 W/m2 for 5 hours, that the substitution of chlorophyll with metal ions Zn2+ and Cu2+ has been shown to form more stable than natural chlorophyll. The characterization of the optical properties, the combination of ZnO / chlorophyll in the form of hybrid films has led to a shift in the absorption region of ZnO becomes more widely from the UV to Visible. ZnO/chlorophyll has absorption range of 350-515 nm, ZnO / Zn-feofitin 332-401 nm and 332-632 nm for Cu-feofitin. The combination of ZnO/chlorophyll and CuSCN as a solid electrolite in hybrid solar cell, a modified chlorophyll with metal ions Zn2+ and Cu2+ has been shown to form a more stable I-V curve. It is characterized by its fill factor value greater than natural chlorophyll. Nevertheless, solar cells with natural chlorophyll has been able to produce higher efficiency values of chlorophyll were substituted.
Keyword: Hydrothermal, ZnO/Chlorophyll modified, Hybrid Solar Cell