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Mahendra Kusuma Nugraha
Universitas Sam Ratulangi
Agriculture, Biological Sciences & Forestry Astronomy Biochemistry, Genetics & Molecular Biology Chemical Engineering, Chemistry & Bioengineering Chemistry Civil Engineering, Building, Construction & Architecture Computer Science & IT Control & Systems Engineering Earth & Planetary Sciences Economics, Econometrics & Finance Education Energy Engineering Environmental Science Health Professions Industrial & Manufacturing Engineering Languange, Linguistic, Communication & Media Law, Crime, Criminology & Criminal Justice Library & Information Science Materials Science & Nanotechnology Mathematics Medicine & Pharmacology Physics Public Health Other

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KARAKTERISASI PLASMA LUCUTAN PIJAR KORONA POSITIF PADA KONDISI ATMOSFER DENGAN KONFIGURASI ELEKTRODA TITIK BIDANG DAN PENGARUHNYA TERHADAP KAIN SUTRA ALAM (BOMBYX MORI) Mahendra Kusuma Nugraha; Zaenul Muhlisin; Pandji Triadyaksa
Arena Tekstil Vol 34, No 1 (2019)
Publisher : Balai Besar Tekstil

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (817.932 KB) | DOI: 10.31266/at.v34i1.4980

Abstract

Eksperimen pembangkitan plasma lucutan pijar korona telah dilakukan dengan menggunakan konfigurasi elektroda titik dan bidang. Kondisi plasma lucutan pijar korona terbentuk secara optimal pada jarak antar elektroda (d) setinggi 2,1 cm dan 2,4 cm dan arus saturasi (Is) terukur sebesar 0,75 mA dan 1,0 mA. Kondisi tersebut digunakan sebagai dua karakteristik lucutan yang digunakan dalam tahap perlakuan sampel kain sutra alam (Bombyx mori). Pengujian sifat mekanis pada sampel kain sutra alam dengan perlakuan plasma menunjukkan nilai ketahanan jebol yang menurun dibandingkan nilai ketahanan jebol pada sampel kain sutra alam tanpa perlakuan. Pengujian kekuatan serap zat cair (akuades) pada sampel kain sutra alam dengan perlakuan plasma menunjukkan nilai rerata waktu serap (τ) yang lebih singkat dibandingkan nilai τ pada sampel kain sutra tanpa perlakuan. Pada kedua tahap tersebut, pengoptimalan maksimum dari nilai ketahanan jebol dan daya serap zat cair (akuades) dicapai pada jarak antar elektroda (d) setinggi 2,1 cm, arus saturasi (Is) sebesar 0,75 mA dan waktu perlakuan selama 30 menit. Pengujian sifat mikroskopik membuktikan bahwa dengan adanya perubahan struktur permukaan pada sampel cukup berpengaruh terhadap nilai ketahanan jebol dan rerata waktu penyerapan zat cair (akuades) yang dimiliki.  Hasil pengujian pada tahap ini juga menyatakan bahwa tidak ada penambahan jenis baru dari gugus fungsi terkandung pada sampel kain sutra alam yang diberi perlakuan plasma.
Performance Characterization of 450 nm Visible Light Based Photoacoustic Imaging for Phantom Imaging of Synthetic Dye Contrast Agents Mahendra Kusuma Nugraha; Moh. Ali Joko Wasono; Mitrayana Mitrayana
INDONESIAN JOURNAL OF APPLIED PHYSICS Vol 12, No 1 (2022): April
Publisher : Department of Physics, Sebelas Maret University

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.13057/ijap.v12i1.49179

Abstract

Performance characterization of 450 nm visible light photoacoustic imaging has been carried out through phantom imaging of methylene blue (MB), methyl orange (MO), and methyl red (MR) dye solutions. The phantom was made of a nylon tube with a diameter of 5.0 mm (outside) and 4.6 mm (inside) having a height of 2.0 mm along with a 6×6 cm black galvanized aluminum plate as the background medium. The nylon tube was filled with each type of solution with varying molecular concentrations of 10, 25, 50 and 100 ppm. Twelve (12) phantom objects were imaged in an area of 10×10 cm. The visible absorption peak known from UV-Visible spectroscopy for each type of solution is at 664 nm (methylene blue), 465 nm (methyl orange), and 522 nm (methyl red). It was also known that the amplitude of PA emissions would increase proportionally to the concentration of dye molecules. Overall, methyl orange solutions had the highest photoacoustic emission amplitude distribution. The analysis showed that the ratio of inner diameter (ID) and wall thickness (WT) between the MB and MO phantom images to the original object were 1:0.83 and 1:0.74 (ID) and 1:3 and 1:1.5 (WT), respectively. On the other hand, the ratio of the outer diameter (OD) of the MR phantom image to the original object is 1:1.28. 
KARAKTERISASI KARBON AKTIF YANG TERBUAT DARI TEMPURUNG KELAPA DENGAN AKTIVASI Na2CO3 DAN SUHU 1000 oC MENGGUNAKAN TEKNIK XRD DAN SEM-EDX Andi Ikhtiar Bakti; Yuanita Amalia Harianto; Mahendra Kusuma Nugraha
CHEMISTRY PROGRESS Vol. 15 No. 2 (2022)
Publisher : Sam Ratulangi University

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.35799/cp.15.2.2022.44495

Abstract

Karbon aktif dihasilkan dari tempurung kelapa melalui aktivasi fisika dan kimia. Metode pirolisis digunakan untuk aktivasi fisika pada suhu optimal 600 oC dan 1000 oC, untuk aktivasi kimia direndam menggunakan zat pengaktif Na2CO3 10%. Dihasilkan dua sampel, aktivasi fisika yaitu 1000oC dan aktivasi fisika-kimia yaitu Na2CO3. Spektrum XRD dari karbon aktif pada sampel 1000 oC dan Na2CO3 masing-masing terkandung mineral silikat, bijih besi dan kuarsa, dan menunjukkan adanya pembentukan struktur karbon dan grafit pada bidang hkl (002) dan (100), dengan metode Scherrer ukuran rata-rata kristal sampel Na2CO3 15,0285 nm dan ukuran rata-rata kristal sampel 1000 oC 54,5299 nm, ukuran kristal nano terbentuk jika suhu meningkat ≥600 oC. Hasil SEM dengan perbesaran 3000 kali, ukuran gambar 5 µm terlihat sangat jelas porositas yang terbentuk adalah 0,8 µm pada sampel Na2CO3 dan 1,00 µm pada sampel 1000 oC. Hasil spekturm EDX menunjukkan kandungan unsur karbon (C) pada sampel Na2CO3 terdapat 96,74% sedangkan untuk sampel 1000 oC terdapat 54,16%.
Gambaran Penyimpanan obat di gudang farmasi RSUD Bolaang Mongondow Selatan Alfamega Pinasang; Gayatri Citraningtyas; Imam Jayanto; Mahendra Kusuma Nugraha
PHARMACON Vol. 12 No. 2 (2023): PHARMACON
Publisher : UNIVERSITAS SAM RATULANGI

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.35799/pha.12.2023.42182

Abstract

The storage of medicines and good health supplies aims to maintain the quality of medicines, avoid irresponsible use, maintain the continuity of supplies and facilitate the search and control. The purpose of this study is to see the picture of drug storage and determine indicators of strengths, weaknesses, opportunities and threats that affect drug storage in the warehouse of the pharmaceutical installation of Bolaang Mongondow Selatan Hospital. This research is a qualitative research conducted with a Single Variable Analytical Descriptive Method. The results showed that the picture of drug storage at BolaangMongondow Selatan Hospital has not fully met the requirements according to drug storage standards in the Minister of Health Regulation no. 72 of 2016 with the value per Bolaang Mongondow Selatan Hospital not fully meeting the storage standards according to Permenkes no. 72 of 2016 because it shows a percentage of < 100%. Where the results of the analysis of the suitability of drug storage conditions (73.68%) and fulfillment of drug storage procedures (72.92%) while logistics management is fairly goodwith the percentage of drug suitability between the stock card and the system 100% and the discovery of expired drugs during the 2022 period. The results of the identification of internal factors include advantages, namely a good pharmaceutical supply structuring system, adequate information system facilities, warehouse heads coming from pharmaceutical personnel, good logistics management cycles, the weakness is that there are frequent power outages, warehouse locations that are not separated from pharmaceutical installations, facilities and infrastructure that are still lacking. The opportunities that have are the development of a good Management Information System while threats, distributor regulations, demand for goods or drugs at night, the location of warehouses that are not separated from pharmaceutical installations allow the risk of losing drugs to be even greater.  Keywords: Drug Storage, Pharmacy Warehouse
Determining the Coefficient of Restitution for Imperfect Elastic Collisions between Glass Marbles and Ceramic Surfaces Mahendra Kusuma Nugraha; Ernawatil Gani; Jumriadi
Jurnal MIPA Vol. 13 No. 2 (2024): Cover
Publisher : Universitas Sam Ratulangi

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.35799/jm.v13i2.56047

Abstract

Time-lapse videography was employed to observe the dynamics of imperfect elastic free-fall collisions between a standard glass marble and a ceramic-tiled floor surface, using a SHARP® Aquos Sense 4+ smartphone camera with a shutter speed of 30 frames per second (fps). The events were recorded and analysed using the frame-splitting method, which was then visually observed to determine the height of each bounce. The analysis revealed that the average coefficients of restitution for the collisions were  and , with the initial free-fall heights being 20.3 cm and 16.2 cm respectively for the first and second trials. These experiments illustrate that every event signifies an imperfect elastic collision, showing how mechanical energy dissipates from the marble into its surroundings since ε is not equal to 1. The slight variations in the coefficient outcomes occur due to the constraints imposed by the laws of thermodynamics. Untuk menyelami potensi lanjut dari videografi jeda-waktu, metode ini digunakan untuk mengamati dinamika tumbukan jatuh bebas elastis tak sempurna antara kelereng kaca dan lantai keramik, menggunakan kamera ponsel SHARP® Aquos Sense 4+ dengan kecepatan rana 30 kerangka per detik. Peristiwa-peristiwa tersebut direkam dan dianalisis menggunakan metode pemisahan kerangka, yang kemudian diamati secara visual untuk menentukan tinggi setiap pantulan. Analisis mengungkapkan bahwa koefisien restitusi rata-rata untuk tabrakan tersebut adalah  dan , dengan tinggi jatuh bebas awal masing-masing adalah 20.3 cm dan 16.2 cm untuk percobaan pertama dan kedua. Eksperimen-eksperimen ini menggambarkan bahwa setiap peristiwa menunjukkan sebuah tumbukan elastis yang tidak sempurna, menunjukkan bagaimana energi mekanik tersebar dari kelerang ke sekitarnya karena ε tidak sama dengan 1. Variasi kecil dalam hasil koefisien terjadi karena batasan yang diberlakukan oleh hukum termodinamika.
Pengaruh Miopi Terhadap Aktivitas Gelombang Alfa pada Otak di Area Oksipital Ernawatil Gani; Mahendra Kusuma Nugraha; Afrioni Roma Rio
Jurnal MIPA Vol. 13 No. 2 (2024): Cover
Publisher : Universitas Sam Ratulangi

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.35799/jm.v13i2.56125

Abstract

Miopi merupakan kondisi mata seseorang yang mengalami kesulitan dalam mengamati objek yang jauh dengan jelas. Kondisi ini akan mempengaruhi kerja sistem saraf di otak. Sistem saraf di otak dapat diketahui melalui beberapa aktivitas gelombang salah satunya gelombang alfa. Gelombang ini berhubngan dengan kemampuan mata memvisualisasikan suatu benda. Sehingga, penelitian ini bertujuan untuk menganalisis kondisi sinyal alfa di otak khususnya area oksipital pada penderita miopi menggunakan metode Power Spectral Density (PSD). Sebanyak tujuh peserta direkam menggunakan EEG Emotiv Epoc masing-masing selama 5 menit dengan mata terbuka tanpa kacamata dan dengan kacamata. Data EEG diolah melalui filtering, rejecting artefak, dan analisis PSD dengan metode Periodogram Welch menggunakan Python. Hasil menunjukkan perbedaan signifikan dalam distribusi daya frekuensi antara area oksipital pada otak bagian kiri (O1) dan bagian kanan (O2), dengan aktivitas alfa yang lebih dominan dan konsisten di O2 pada frekuensi 10-11 Hz. Dengan demikian, kondisi ini mengindikasikan aktivitas neural yang lebih intens di oksipital kanan pada penderita miopi, mungkin sebagai bentuk kompensasi atau adaptasi dalam pemrosesan visual. Analisis lebih lanjut diperlukan untuk memahami implikasi penuh dari aktivitas neural ini dan untuk memastikan hasil yang lebih valid melalui teknik pengolahan sinyal yang lebih canggih. Myopia is a condition in which a person's eyes have difficulty seeing distant objects clearly, affecting the neural system's function in the brain. The nervous system of the brain can be identified through several wave activities, including alpha waves, which are related to the eye's ability to visualize objects. Therefore, this study aims to analyze the condition of alpha signals in the brain, specifically in the occipital area, of individuals with myopia using the Power Spectral Density (PSD) method. Seven participants were recorded using the EEG Emotiv Epoc for 5 minutes each with eyes open, both with and without glasses. The EEG data was processed through filtering, artifact rejection, and PSD analysis using the Welch Periodogram method in Python. The results showed significant differences in the frequency power distribution between the occipital on the left side of the brain (O1) and on the right side (O2), with more dominant and consistent alpha activity in O2 at 10-11 Hz. This indicates more intense neural activity in the right occipital region in myopic individuals, possibly as a form of compensation or adaptation in visual processing. Further analysis is required to fully understand the implications of this neural activity and to ensure more valid results through advanced signal processing techniques.
Penentuan Nilai Koefisien Restitusi Kelereng Kaca menggunakan Metode Pencitraan Jeda Waktu Sederhana Mahendra Kusuma Nugraha; Ernawatil Gani; Berton Maruli Siahaan; Afrioni Roma Rio
JFT : Jurnal Fisika dan Terapannya Vol 10 No 2 (2023): DESEMBER
Publisher : Universitas Islam Negeri Alauddin Makassar

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.24252/jft.v10i2.36479

Abstract

Time-lapse imaging has been performed to observe the physical phenomena of imperfect elastic collisions between a glass marble and a tiled floor surface. The glass marble is dropped at a certain height until it hits the floor and experiences repeated rebounds. The event was recorded using the Infinix® Hot S3 smartphone device camera with a shutter speed of 30 frames per second. Analysis of time lapse photography is then carried out using the frame splitting method which is then observed visually to determine the height of each reflection that occurs. The results of the analysis and measurement of the maximum height for the initial state, the first bounce state and the second bounce state are respectively: 15.7 cm, 13.65 cm and 11.45 cm. The coefficient of restitution of glass marbles—based on the data obtained—at the initial maximum height ( towards the first reflection ( ) is ± 0.93242 and the first reflection ( ) towards the second reflection ( ) is equal to. ±0.91587. These results prove that the interaction that occurs is an imperfect elastic collision interaction due to . Keywords: marble, maximum height, restiution coefficient, time-lapse imaging.
The Effect of Myopia on Brain Signals: Insights from EEG Studies Gani, Ernawatil; Rio, Afrioni Roma; Nugraha, Mahendra Kusuma; Haryanto, Freddy
Jurnal Penelitian Fisika dan Aplikasinya (JPFA) Vol. 14 No. 1 (2024)
Publisher : Universitas Negeri Surabaya

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.26740/jpfa.v14n1.p19-32

Abstract

Refractive vision disorders, such as myopia, can significantly influence an individual's cognitive performance, particularly their ability to perceive and interpret visual stimuli. Myopia, a common refractive error affecting children and adults, can be assessed using various methods, including electroencephalography (EEG). The primary objective of this investigation was to identify distinctive brain signals associated with myopia. This study delves into analyzing brain signals in myopic individuals by employing EEG data and spectral entropy analysis through MNE-Python. EEG data were collected from five myopic participants during a 10-minute session, both with and without their corrective glasses. The collected data underwent preprocessing and power spectral density calculations. Subsequently, spectral entropy analysis was employed to assess the complexity and distribution skewness of EEG frequency patterns. The results of this study revealed notable differences in brain activity, particularly in the occipital region, between individuals wearing glasses and those without them. This variance could be attributed to the enhanced visual clarity experienced by individuals wearing glasses, enabling them to perceive better and process the visual stimuli presented in the study videos. Specifically, spectral entropy values were lower in children without glasses (averaging 1.0) than those with glasses (averaging 3.5), indicating a higher degree of irregularity in the brain activity of myopic children who do not wear corrective eyewear. In conclusion, this study indicates an increase in brain activity irregularities among children without glasses. The findings suggest that specific factors, such as blinking and hand movements, play a role in exacerbating this irregularity. These findings reveal how myopia affects brainwave patterns and indicate that EEG and spectral entropy analysis can enhance our understanding of refractive vision disorders.
Prediksi Biaya Pemakaian Listrik Dengan Metode Logika Fuzzy Mamdani Zalmi, Wahyuni Fithratul; Pang, David; Nurgraha, Mahendra Kusuma
Jurnal Informatika Vol 12, No 3: INFORMATIKA
Publisher : Fakultas Sains & Teknologi, Universitas Labuhanbatu

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.36987/informatika.v12i3.6337

Abstract

Understanding the electricity tariff class is needed to predict how much usage costs or electricity bills that must be incurred by customers. Each power capacity has a different basic electricity tariff based on the class, household, business and industry. Fuzzy logic can solve problems with imprecise and heuristic data by producing accurate conclusions. The conclusion obtained from the Fuzzy Logic results is expected to be a consideration for customers in predicting electricity usage costs based on electricity tariff groups and customer electrical power capacity. The proposed research uses the Mamdani Fuzzy Logic Method, the use of this method aims to facilitate customers in predicting the cost of electricity usage based on the electricity tariff class and the customer's electric power capacity. The output of this research is the result of predicting the cost of electricity usage based on the power group in residential homes. The higher the tariff group, the number of kWh, electronic goods, and usage time, the higher the predicted energy consumption used. The results obtained from adjusting the fuzzy input antecedents and fuzzy values, namely [900;850;30;20], then for Type_Tariff Power 900, Total_KWh 850, Electronics 30, and Time_Use 20 is 986. Then the cost that must be incurred in the example case above is 1,333,072 rupiah.
EDUKASI DAN INOVASI PANGAN FUNGSIONAL DALAM MENGENDALIKAN STUNTING DI SEKOLAH-SEKOLAH KECAMATAN PINELENG KABUPATEN MINAHASA Sudewi, Sri; Sutrisna, Agung; Nugraha, Mahendra Kusuma; Jayanto, Imam; Antasionasti, Irma
Jurnal Abdi Insani Vol 11 No 4 (2024): Jurnal Abdi Insani
Publisher : Universitas Mataram

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.29303/abdiinsani.v11i4.1997

Abstract

Stunting is a growth and development disorder in children caused by chronic malnutrition and recurrent infections characterized by substandard height. School children generally neglect breakfast because they are busy in the morning, easily bored with food consumed daily which is traditionally processed by boiling, stir-frying, frying, steaming. The majority of children and teachers in this school do not know clearly about stunting, its causes, impacts, and how to overcome it. This service aims to provide counseling on education about stunting and introduce local foods that can function as stunting prevention by making functional food innovations. The method was carried out by measuring the child's weight, height, and arm circumference as early indicators of stunting. Providing counseling to children and teachers about stunting, its causes, impacts, and how to overcome it and providing functional food innovation products processed from surrounding plants. The results of this service activity showed that the results of monitoring the measurement of weight, height, and arm circumference were 4 students whose body condition was below the ideal standard of children at MIN 1 Minahasa school. No body condition was found below normal standards at Ra Nurut Takwa Kindergarten school. Children's knowledge about stunting and the benefits of local plants in Sea Village that can be used as functional food has increased. Nutritious gifts containing high protein were also distributed to children in the form of milk, vitamin C, cheese, milk candy, jelly candy as a result of the Team's functional food product innovation whose material was sourced from comedy shows. This service can be concluded that education about stunting in children in schools has had a positive impact on improving health, increasing knowledge, monitoring potential and further prevention of stunting.
Co-Authors Afrioni Roma Rio Alfamega Pinasang Antasionasti, Irma Bakti, Andi Ikhtiar David Pang Ernawatil Gani, Ernawatil Freddy Haryanto Gayatri Citraningtyas Hariyanto, Yuanita Amalia Imam Jayanto Jayanto, Imam Jayawarsa, A.A. Ketut Jumriadi Mitrayana - Moh Ali Joko Wasono Pandji Triadyaksa Rendy Syahputra Siahaan, Berton M. Sri Sudewi, Sri Sutrisna, Agung Zaenul Muhlisin Zalmi, Wahyuni Fithratul