Judul: Factors Affecting Compulsive Buying Behavior in Online Shopping Post COVID-19 Pandemic
Abstrak: COVID-19 telah menciptakan krisis kesehatan global yang berdampak mendalam pada cara masyarakat dalam memandang dunia dan kehidupan sehari- hari. Krisis kesehatan seperti COVID-19, dapat menjadi pemicu utama masyarakat untuk melakukan compulsive buying. Penelitian ini bertujuan untuk menganalisis perubahan karakteristik masyarakat di Jakarta, menganalisis pengaruh media exposure, personality factors, dan external offerings terhadap compulsive buying pada online shopping pasca pandemi COVID-19 di Jakarta. Total responden yang diperoleh adalah 220 orang. Data yang digunakan dalam penelitian ini adalah data primer dan data sekunder. Penelitian ini menggunakan metode analisis deskriptif, uji chi-square, dan SEM-PLS. Hasil dari penelitian ini adalah personality factors memengaruhi compulsive buying melalui materialism dan arousal. Media exposure tidak berpengaruh signifikan dengan compulsive buying, tetapi media exposure berpengaruh positif signifikan dengan response towards COVID-19 dan response towards COVID-19 berpengaruh positif signifikan dengan compulsive buying. Variabel external offerings tidak berpengaruh signifikan dengan compulsive buying pada online shopping pasca pandemi COVID-19 di Jakarta., COVID-19 has created a global health crisis that has a profound impact on the way people view the world and their daily lives. A health crisis such as COVID- 19, can be a major trigger for people to do a compulsive buying. This study aims to analyze changes in the characteristics of people in Jakarta, to analyze the influence of media exposure, personality factors, and external offerings on compulsive buying in online shopping after the COVID-19 pandemic in Jakarta. Total respondents obtained were 220 people. The data used in this study are primary data and secondary data. This research uses descriptive analysis method, chi-square and SEM-PLS. The result of this study is that personality factors affect compulsive buying through materialism and arousal. Media exposure does not have significant affect directly compulsive buying, but media exposure has a significant effect on the response towards COVID-19 and response towards COVID-19 has a significant effect on compulsive buying. The external offerings variable did not affect compulsive buying on online shopping after the COVID-19 pandemic in Jakarta.
Keyword: Compulsive Buying, External Offerings, Media Exposure, Personality Factors

Judul: Pengaruh Psychological Factors, Financial  Literacy, dan Paylater Misuse terhadap Compulsive Buying
Abstrak: Peningkatan tren belanja online melalui e-commerce di masa pandemi Covid-19 turut didukung dengan perkembangan metode pembayaran digital, salah satunya paylater. Paylater memungkinkan konsumen untuk membeli barang sekarang dan membayarnya kemudian dengan cicilan setiap bulan. Pertumbuhan paylater di Indonesia dapat mendorong perkembangan ekonomi digital dan selaras dengan tujuan pembangunan berkelanjutan (Sustainable Development Goals/SDGs). Namun, apabila tidak dikendalikan, penggunaan paylater justru berisiko memicu perilaku compulsive buying dan meningkatkan jumlah hutang yang dimiliki konsumen. Penelitian ini bertujuan untuk menganalisis karakteristik pengguna paylater di Jabodetabek, menganalisis pengaruh psychological factors dan financial literacy terhadap paylater misuse, dan menganalisis pengaruhnya terhadap compulsive buying. Penelitian ini menggunakan sampel sebanyak 275 responden pengguna paylater di Jabodetabek. Sampel penelitian ditentukan menggunakan metode non-probability sampling jenis convenience sampling dan quota sampling. Selanjutnya, hasil penelitian dianalisis menggunakan analisis deskriptif dan Structural Equation Modeling-Partial Least Squares (SEM-PLS). Hasil penelitian ini menunjukkan bahwa psychological factors, financial literacy, dan paylater misuse memiliki pengaruh yang positif dan signifikan terhadap compulsive buying., The increasing trend of online shopping through e-commerce during the Covid-19 pandemic is also supported by the development of digital payment method, one of which is paylater. Paylater allows consumers to buy now and pay later in monthly installments. Paylater growth in Indonesia can encourage the development of the digital economy and is in line with sustainable development goals (SDGs). However, if not controlled, the use of paylaters actually risks triggering compulsive buying behavior and increasing the amount of debt owned by consumers. This research aims to analyze the characteristics of paylater users in Jabodetabek, analyze the influence of psychological factors and financial literacy toward paylater misuse, and analyze its influence toward compulsive buying. The sample of this research was 275 respondents of paylater users in Jabodetabek. The research sample was determined using the non-probability sampling method, types convenience sampling and quota sampling. Furthermore, the research results were analyzed using descriptive analysis and Structural Equation Modeling-Partial Least Squares (SEM-PLS). The results of this research show that psychological factors, financial literacy, and paylater misuse have a positive and significant effect on compulsive buying.
Keyword: compulsive buying, paylater, SDGs, SEM-PLS

Judul: Hamiltonian formulation for linear waves motion in two layers fluid
Abstrak: The surface wave could be considered as a wave that separates two fluids, namely water and air. Based on this assumption, it is introduced the interfacial wave, a wave between two layers of fluid with different density. The formulation of interfacial waves motion begins with deriving the base equation of irrotational ideal fluid. Furthermore, according to irrotational fluid assumption, the base equation can be stated in velocity potential. In this derivation, the fluids domain is assumed to be restricted by rigid lid boundary conditions, both at the upper and lower limit. Therefore, the interfacial waves motion can be explained in a hamiltonian formulation. In the hamiltonian formulation, total energy is defined as the sum of kinetic and potential energy. The hamiltonian system is obtained from reduction of kinetic energy by using the Dirichlet Neumann Operator. The resulted kinetic energy equation is nonlinear. Therefore, this form is linearized by first part of the Taylor expansion. This linearization gives a dispersion relation of linear wave. Based on this dispersion relation, the phase speed of the linear wave depends on the density ratio of the two layers fluid.
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