Judul: Analysis of Market Structure and Competitiveness of Indonesian Apparel in the United States
Abstrak: Tekstil dan Produk Tekstil (TPT) selama bertahun-tahun telah menjadi komoditas ekspor utama Indonesia. Sektor industri TPT Indonesia seperti contohnya pada industri pakaian jadi masih memiliki permasalahan khususnya pada daya saing di pasar internasional. Berdasarkan pernyataan tersebut penelitian ini bertujuan untuk menganalisis struktur pasar dan daya saing pakaian jadi Indonesia di Amerika Serikat yang diperlukan dalam menyusun strategi untuk memperluas pangsa pasar. Hasil dari penelitian ini menunjukkan bahwa dari analisis Herfindahl Index (HI) dan Concentration Ratio (CR4) disimpulkan pasar pakaian jadi di Amerika Serikat memiliki struktur oligopoli dengan konsentrasi sedang. Nilai Revealed Comparative Advantage Indonesia yang lebih dari satu menunjukan Indonesia memiliki keunggulan komparatif pada pasar pakaian jadi di Amerika Serikat. Hasil analisis menggunakan Export Product Dynamic (EPD) menunjukkan bahwa Indonesia sempat berada pada posisi lost opportunity pada periode kedua (2012-2015), namun mampu bangkit ke posisi rising star pada periode ketiga (2016-2020). Analisis Porter’s Diamond menunjukkan bahwa banyak faktor yang belum menunjukkan keunggulan kompetitif pakaian jadi Indonesia, namun ada beberapa faktor yang memiliki keunggulan kompetitif seperti sumber daya manusia yang berlimpah dan murah serta ekspor pakaian jadi ke Amerika Serikat yang terus meningkat., Textiles and Textile Products (TPT) has become Indonesia's main export commodity for many years. The Indonesian TPT industry, especially the apparel industry, still has competitiveness problems in the international market. Therefore, this study aims to analyze the competitiveness and structure of the apparel market in the United States (US) which can be useful for developing strategies to expand market share. The results of this study indicate that from the analysis of the Herfindahl Index and Concentration Ratio it is concluded that the apparel market in the US has an oligopoly structure with moderate concentration. Indonesia's Revealed Comparative Advantage value which is more than one indicates that Indonesia has a comparative advantage in apparel market in the US. The results of the analysis using Export Product Dynamic show that Indonesia was in a lost opportunity position in the second period (2012-2015) but was able to rise to a rising star position in the third period (2016-2020). Porter's Diamond analysis shows that there are many factors that do not show the competitive advantage of Indonesian apparel, but there are several factors that have competitive advantages such as abundant and affordable human resources and the increasing exports of apparel to the US.
Keyword: Cotton, Concentration Ratio, EPD, Porter’s Diamond, RCA

Judul: Market Structure and Competitiveness of  Indonesian Natural Rubber in the United States
Abstrak: Karet alam Indonesia berperan penting untuk meningkatkan perekonomian nasional melalui ekspor karet alam ke berbagai negara, termasuk Amerika Serikat. Indonesia perlu melakukan identifikasi posisi dan daya saing karet alam di antara negara pesaing serta peluang pasarnya ke Amerika Serikat. Tujuan penelitian ini adalah menganalisis struktur pasar, keunggulan komparatif dan kompetitif karet alam Indonesia di pasar Amerika Serikat. Analisis dilakukan pada periode tahun 2008 dan 2019 melalui metode Herfindahl Index (HI), Concentration Ratio (CR4), Revealed Comparative Advantage (RCA), Export Product Dynamic (EPD), dan Diamond’s Porter. Hasil analisis menemukan bahwa struktur pasar karet alam Indonesia adalah monopoli dan cenderung sedikit oligopoli. Dibandingkan dengan negara-negara eksportir lainnya, karet alam Indonesia memiliki keunggulan komparatif di pasar Amerika Serikat dengan nilai RCA>1. Keunggulan kompetitif karet alam Indonesia di Amerika Serikat mengalami penurunan dari posisi lost opportunity pada periode pertama (2008-2011) menjadi retreat pada periode ketiga (2016-2019). Hasil dari Diamond’s Porter menunjukkan bahwa terdapat tujuh faktor keunggulan kompetitif dan tiga faktor kelemahan dalam industri karet alam di Indonesia., Indonesian natural rubber plays a significant role in improving the national economy by exporting natural rubber to various countries, including the United States. Indonesia must identify its natural rubber position and competitiveness among competing countries and market opportunities in the US. This study aims to analyze the market structure, comparative advantage and competitiveness of Indonesian natural rubber in the US market. The analysis was carried out in the period 2008 and 2019 through methods, including Herfindahl Index (HI), Concentration Ratio (CR4), Revealed Comparative Advantage (RCA), Export Product Dynamic (EPD), and Diamond's Porter. The analysis found that the natural rubber market structure in Indonesia is monopolistic and tends to be oligopolistic. Compared to other exporting countries, Indonesian natural rubber has comparative advantage in the US market, as indicated by the RCA>1. The competitiveness of Indonesian natural rubber in the US decline overtime from the lost opportunity position in the first period (2008-2011) to retreat in the third period (2016-2019). The diamond's porter results show that there are seven competitive advantage factors and three weakness factors in Indonesia's natural rubber industry.
Keyword: concentration ratio, diamond’s porter, EPD, herfindahl index, RCA

Judul: Dynamical System of Hepatitis B in Three Groups with Vaccination
Abstrak: The aim of this study is to modify the hepatitis B transmission model in three age groups involving vaccination from the model conducted by Zhoe and Zhang.The method used is to analyze the stability of the fixed point and its basic reproduction number (R_0). Performed stability analysis and numerical simulation to see population dynamics. Next, a sensitivity analysis of the parameters was carried out to see its effect on R_0. From the analysis obtained two fixed points, namely non-endemic and endemic fixed points. Non-endemic fixed points are locally asymptotically stable if R_0 <1 Meanwhile, the endemic fixed point is locally asymptotically stable if R_0 > 1. Hepatitis vaccination affects the number of susceptible population, because the more successful the vaccination, the smaller the number of susceptible populations so that the smaller the population will be infected.
Keyword: Dynamic, Hepatitis B, Vaccine, Mathematical model