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All Journal Jurnal Rekayasa Material, Manufaktur & Energi JOURNAL OF SCIENCE AND SOCIAL RESEARCH Journal of Technomaterial Physics Instal : Jurnal Komputer CHEDS: Journal of Chemistry, Education, and Science EINSTEIN (E-JOURNAL)
Ong, Russell
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Aerospace Engineering Astronomy Biochemistry, Genetics & Molecular Biology Chemistry Civil Engineering, Building, Construction & Architecture Computer Science & IT Control & Systems Engineering Decision Sciences, Operations Research & Management Earth & Planetary Sciences Economics, Econometrics & Finance Education Electrical & Electronics Engineering Energy Engineering Materials Science & Nanotechnology Mechanical Engineering Physics Social Sciences

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Sentiment Analysis of Platform X Users on Starlink Using Naive Bayes M. Khalil Gibran; Rifki, Mhd Ikhsan; Hasugian, Abdul Halim; Siahaan, Ahmad Taufik Al Afkari; Afandi Sahputra; Ong, Russell
Bahasa Indonesia Vol 16 No 03 (2024): Instal : Jurnal Komputer
Publisher : Cattleya Darmaya Fortuna

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.54209/jurnalinstall.v16i03.240

Abstract

This research aims to analyze public sentiment towards Starlink through tweets collected using the hashtag "starlink." The data crawling process was successful in collecting 1888 tweets. However, upon checking and processing the data, we reduced the number of valid and relevant tweets to 416. This reduction occurred due to duplicate data and the use of common keywords. We performed sentiment classification using the Naive Bayes model, yielding the following sentiment distribution: We classified 287 tweets (68.99%) as positive, 112 tweets (26.92%) as neutral, and 17 tweets (4.09%) as negative. The model performance evaluation shows good results with a recall of 0.80, precision of 0.90, F1 score of 0.83, and accuracy score of 0.80. The results of this study indicate that the majority of tweets related to Starlink have positive sentiments, indicating a generally favorable public perception of the service. A small proportion of tweets showed neutral and negative sentiments, which can provide valuable input for service improvement. The Naive Bayes model is able to classify sentiment with fairly high accuracy, making it one of the most effective tools for sentiment analysis.
An In-depth Study of Relation Between Band Gap Energy and Lattice Constant for Cubic Phase LiSnX3 (X = F, Cl, Br, and I) Perosvkite Ong, Russell; Sagala, Junaina Sahputri; Rahayu, Siti Utari
Journal of Technomaterial Physics Vol. 7 No. 1 (2025): Journal of Technomaterial Physics
Publisher : Talenta Publisher

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.32734/jotp.v7i1.19772

Abstract

Organic perovskites or inorganic perovskites are very popular among researchers who are designing the most efficient perovskite solar cells. Besides, they can be used as materials for other optoelectronic applications, such as light-emitting diodes. In this paper, we reported the results of studies on the electronic property of LiSnX3 (X = F, Cl, Br, or I) perovskite in the cubic phase. This electronic property is the density of states, which one can determine the band gap energy value. These studies were undertaken to understand the relation between their band gap energy and lattice constant through anion X variations. The Quantum ESPRESSO program calculated These two crucial quantities with norm-conserving Troullier-Martins pseudopotentials and Generalized Gradient Approximation Perdew-Burke-Enzerhof exchange-correlation functional. The computation results show that the band gap energy ranged from 0,3 eV to 0,99 eV while the lattice constant ranged from 6,183 Å to 4,625 Å for anion halide from I till F, respectively. The contrast trend between these quantities' values matches the Kronig-Penney Model.
CALCULATION OF ELECTRONIC PROPERTIES OF LiBX3 (B = Pb AND Sn; X = Br, Cl AND I) CUBIC PHASE BY DENSITY FUNCTIONAL THEORY Sagala, Junaina Sahputri; Sirait, Ratni; Ong, Russell
EINSTEIN (e-Journal) Vol. 12 No. 3 (2024): EINSTEIN (e-Journal)
Publisher : Universitas Negeri Medan

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.24114/ein.v12i3.61583

Abstract

Perovskite solar cells utilize perovskite as the active material to convert sunlight into electrical energy. Perovskite is a compound with a crystal structure of ABX₃, where A and B are cations, and X is an anion, usually a halide. Research continues to find perovskites with high efficiency. This efficiency is related to the electronic structure, which can be analyzed using Density Functional Theory (DFT). In this study, the electronic structure of cubic phase LiBX₃ perovskites (B = Pb and Sn; X = Br, Cl, and I) is investigated using Quantum ESPRESSO software. Various parameters such as cut-off energy, k-points, and lattice constants were modified to obtain optimal values. From the optimization results, the band gap, DOS, and PDOS values for the six perovskites were obtained. The resulting band gap energy (Eg) are LiPbBr₃ at 1,71 eV, LiPbCl₃ at 1,87 eV, LiPbI₃ at 1,43 eV, LiSnBr₃ at 0,51 eV, LiSnCl₃ at 0,65 eV, and LiSnI₃ at 0,28 eV. These results show that the band gap energy values increase with the change in atomic radius from Sn to Pb and decrease with the change in atomic radius from Cl, Br to I. The electronic structure calculations of LiBX₃ (B = Pb and Sn; X = Br, Cl, and I) show semiconductor properties that have the potential to be used as light-absorbing materials in perovskite solar cells. This study states that LiBX₃ has great potential in solar cell applications and offers a deep understanding of the relationship between crystal structure and its electronic properties.
Efektivitas Adsorben Berbasis Alginat Dan Karbon Aktif Ampas Kopi Dalam Menurunkan Kadar Cod Limbah Cair Industri Tahu Aisyah, Siti Nur; Daulay, Abdul Halim; Ong, Russell
Rekayasa Material, Manufaktur dan Energi Vol 8, No 2: JULI 2025
Publisher : Fakultas Teknik UMSU

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.30596/rmme.v8i2.23222

Abstract

Oxygen Demand (COD), requiring treatment before disposal into the environment. This study aims to evaluate the effectiveness of an adsorbent based on coffee waste-derived activated carbon and sodium alginate in reducing COD levels in tofu wastewater. The activated carbon used has been tested for quality and meets the Indonesian National Standard (SNI 06-3730-1995). The remediation process was conducted using five different adsorbent composition variations. The results showed that the combination of coffee waste-derived activated carbon and sodium alginate significantly reduced COD levels, achieving a maximum reduction efficiency of 90.55% at the optimum variation (Sample E). The adsorption mechanism involving alginate polymers and the porosity of activated carbon contributed to the effective removal of organic compounds from the wastewater. Based on the analysis, this method has proven to be effective in reducing COD levels, making it a potential environmentally friendly alternative for treating tofu industry wastewater.
CALCULATION OF ELECTRONIC PROPERTIES AND MECHANICAL PROPERTIES OF CUBIC PHASE CH3NH(3)PbCl3 USING DENSITY FUNCTIONAL METHOD Ong, Russell; Sagala, Junaina Sahputri
EINSTEIN (e-Journal) Vol. 13 No. 1 (2025): EINSTEIN (e-Journal)
Publisher : Universitas Negeri Medan

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.24114/eins.v13i1.63453

Abstract

Organic-inorganic hybrid halide perovskite-based solar cells such as CH3NH3PbCl3 are known to have many advantages such as low price, simple preparation process and high photoelectric conversion rate. Therefore, we performed theoretical calculations to determine the electronic properties and mechanical properties of CH3NH(3)PbCl3material with space group p3m3 with bulk system in this study. Both properties are calculated by the Density Functional Theory (DFT) method through Quantum ESPRESSO software. The electronic properties discussed include electronic band structure, density of states (DOS) curve, and projected density of state s (PDOS) curve, while the mechanical properties include elasticity constant (Cij), limb modulus (B), Young's modulus (E), shear modulus (G), and Poisson's ratio (ʋ). To determine these properties, the optimum lattice constant must be achieved through optimization of k-points and cut-off kinetic energy. The results show that the value of the lattice gap is 2.49 eV, and C11, C21, C44, limbal modulus, Young's modulus, shear modulus, and Poisson's ratio are 143.83 GPa, 21.22 GPa, 28.24 GPa, 62.09 GPa, 101.75 GPa, 41.47 GPa, and 0.23 GPa, respectively. This shows that the cubic phase CH3NH3PbCl3 waste material is mechanically stable which also has great potential as a perovskite semiconductor material.
PENGARUH pH TERHADAP TURBIDITI NIRA ENCER DAN SUHU IMBIBISI TERHADAP HASIL EKSTRAKSI NIRA SEBAGAI BAHAN PEMBUATAN GULA KRISTAL PUTIH Silalahi, Homsiah Mayang Sari; Hafiza, Nurul; Tiara, Finky Manda; Saputri, Rani; Husnah, Miftahul; Ong, Russell
CHEDS: Journal of Chemistry, Education, and Science Vol 7, No 2 (2023)
Publisher : Universitas Islam Sumatera Utara

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.30743/cheds.v7i2.8133

Abstract

Gula pasir merupakan kebutuhan pokok yang sangat penting bagi rumah tangga dan masyarakat terutama dalam hal pangan. Salah satu hal yang perlu dilakukan untuk menghasilkan gula pasir yang baik adalah dengan melakukan proses ekstraksi nira. Parameter penentuan mutu gula berdasarkan SNI 3140.3:2010 adalah kekeruhan. Salah satu faktor yang mempengaruhi nilai kekeruhan nira encer adalah pH. Semakin tinggi nilai pH maka semakin rendah nilai kekeruhan getah encer. Metode penelitian yang digunakan dalam proses ekstraksi nira adalah dengan menggunakan metode eksperimen langsung. Nilai kekeruhan terendah pada shift 1 pada pH 6,98 sebesar 91 NTU, pada shift 2 pada pH 6,85 sebesar 94 NTU, pada shift 3 pada pH 7,30 sebesar 94 NTU. Hasil dari proses ekstraksi nira ini berupa nilai %Brix, %Pol, dan HK. Semakin tinggi suhu imbibisi maka diperoleh nilai %Brix, %Pol, dan HK tertinggi dengan nilai %Brix 13,64%, %Pol 10,04%, dan HK 73,61 tertinggi pada mill I pada suhu 95°C. Hasil ekstraksi getah tertinggi dapat digunakan dalam pembuatan Gula Kristal Putih (GKP).
PENGARUH PENGGUNAAN SUMBER ENERGI POWER SUPPLY DAN PWM DC TERHADAP EFISIENSI REAKTOR HIDROGEN Sulistiawati, Siti; Nasution, Mulkan Iskandar; Ong, Russell
JOURNAL OF SCIENCE AND SOCIAL RESEARCH Vol 8, No 4 (2025): November 2025
Publisher : Smart Education

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.54314/jssr.v8i4.4836

Abstract

Abstract: Hydrogen was chosen as an environmentally friendly alternative energy obtained through the water electrolysis process. In addition to being environmentally friendly, hydrogen also has a high level of electrical energy efficiency. This study aims to determine the effect of the use of electrical energy sources and frequency on the efficiency of a water electrolysis-based hydrogen reactor and to determine the use of energy sources in a hydrogen reactor as an optimal hydrogen producer. The water electrolysis process is influenced by factors such as voltage, current, power, and frequency given to the reactor. Tests were carried out with variations in voltage of 20V, 22V, 24V, 26V, 28V and 30V and frequencies of 23.69kHz, 24.87kHz, 25.64kHz, 26.31kHz, 26.73kHz. The parameters observed include voltage, current, power, H2 gas yield in ppm, temperature, and hydrogen production efficiency in %. The results of the study showed that the effect of using a frequency source was able to achieve a higher efficiency of 41% with an average current of 0.29A, an average power of 7.12 watts, with an average temperature of 30.150C, while the use of a Power Supply Amplifier (PSA) electrical energy source only produced an efficiency of 25%, with an average current of 0.38A, an average power of 9.81 watts, and an average temperature of 28.50C. The optimal value at the highest efficiency was obtained at an optimal frequency of 23.69 kHz with a temperature of 29.00C, a current of 0.20A, a power of 4.8 watts, and an efficiency of 51.57%. Keyword: Electrolysis, Hydrogen, Frequency, Power Supply, Efficiency Abstrak: Hidrogen dipilih sebagai energi alternatif ramah lingkungan yang diperoleh melalui proses elektrolisis air. Selain ramah lingkungan, hidrogen juga memiliki tingkat efisiensi energi listrik yang tinggi. Penelitian ini bertujuan untuk mengetahui pengaruh penggunaan sumber energi listrik dan frekuensi terhadap efisiensi reaktor hidrogen berbasis elektrolisis air dan untuk mengetahui penggunaan sumber energi pada reaktor hidrogen sebagai penghasil hidrogen yang optimal. Proses elektrolisis air dipengaruhi oleh faktor tegangan, arus, daya, serta frekuensi yang diberikan pada reaktor. Pengujian dilakukan dengan variasi tegangan 20V, 22V, 24V, 26V, 28V dan 30 V dan frekuensi pada 23,69kHz, 24,87kHz, 25,64kHz, 26,31kHz, 26,73kHz. Parameter yang diamati meliputi tegangan, arus, daya, hasil gas H2 dalam ppm, suhu, serta efisiensi produksi hidrogen dalam satuan %. Hasil penelitian menunjukkan bahwa pengaruh penggunaan sumber  frekuensi mampu mencapai efisiensi lebih tinggi yaitu sebesan 41% dengan arus rata-rata 0,29A, daya rata-rata 7,12watt, dengan suhu rata-rata 30,150C, Sedangkan pada penggunaan sumber energi listrik Power Supply Amplifier (PSA) hanya menghasilkan efisinesi sebesar 25%, dengan arus rata-rata 0,38A, daya rata-rata 9,81 watt, dan suhu rata-rata 28,50C. Nilai optimal pada efisiensi tertinggi diperoleh pada frekuensi optimal 23,69 kHz dengan suhu 29,00C, arus 0,20A, daya 4,8 watt, dan efisiensi 51,57%. Kata kunci: Elektrolisis, Hidrogen, Frekuensi, Power Supply, Efisiensi     
Co-Authors Abdul Halim Daulay Abdul Halim Hasugian Afandi Sahputra Hafiza, Nurul M. Khalil Gibran Mhd Ikhsan Rifki Miftahul Husnah Nasution, Mulkan Iskandar Rahayu, Siti Utari Ratni Sirait, Ratni Sagala, Junaina Sahputri Saputri, Rani Siahaan, Ahmad Taufik Al Afkari Silalahi, Homsiah Mayang Sari Siti Nur Aisyah Sulistiawati, Siti Tiara, Finky Manda