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All Journal Research Report - Engineering Science JURNAL FISIKA Jurnal Penelitian Pembelajaran Fisika International Journal of Artificial Intelligence Research INDONESIAN JOURNAL OF APPLIED PHYSICS Jurnal Fisika Indonesia
Risti Suryantari
Universitas Katolik Parahyangan
Astronomy Computer Science & IT Earth & Planetary Sciences Education Electrical & Electronics Engineering Energy Engineering Materials Science & Nanotechnology Physics

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Problem Solving dengan Metode Identifikasi Variabel berdasarkan Skema: Tinjauan terhadap Formulasi Hukum Pertama Termodinamika Risti Suryantari
Jurnal Fisika Indonesia Vol 17, No 49 (2013)
Publisher : Department of Physics Universitas Gadjah Mada

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (174.432 KB) | DOI: 10.22146/jfi.24409

Abstract

Metode identifikasi variabel berdasarkan skema merupakan  salah satu metode problem solving dalam fisika terkait formulasi.  Metode ini telah diterapkan bagi formulasi kecepatan relativistik, serta panjang dan waktu relativistik. Pada penelitian kali ini akan diterapkan metode serupa bagi topik termodinamika,. Hukum Pertama Termodinamika melibatkan tiga variabel yaitu kalor, usaha dan perubahan energi dalam. Terdapat dua jenis proses dalam sistem termodinamika , yaitu kalor dan usaha diberikan pada sistem atau dihasilkan oleh sistem. Pada berbagai buku referensi, hal tersebut dicirikan dengan tanda positif dan negatif. Permasalahan yang ditemui adalah kemungkinan terjadinya kesalahan pada perhitungan, terutama jika  siswa tidak menentukan tanda positif atau negatif tersebut dengan benar. Skema akan membantu siswa dalam menyelesaiakan soal terkait formulasi ini, tanpa harus memikirkan tanda positif atau negatif pada variabel kalor dan usaha. Metode ini akan diterapkan pada contoh-contoh soal sederhana dan diimplementasikan terhadap mahasiswa Program Studi Fisika Universitas Katolik Parahyangan Bandung. Hasil penelitian menunjukkan seluruh mahasiswa dapat menyelesaikan soal dengan benar dan berpendapat bahwa metode ini lebih mudah untuk dipahami. Guru atau para pengajar fisika dapat menggunakan metode ini sebagai variasi dalam pembelajaran, sehingga formulasi tidak lagi dianggap sulit dalam fisika.
ANALISIS CITRA PERMUKAAN THERMOCHROMIC LIQUID CRYSTAL BERDASARKAN NILAI STATISTIK HUE Risti Suryantari; - Flaviana
Jurnal Fisika Vol 4, No 1 (2014)
Publisher : Universitas Negeri Semarang

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.15294/jf.v4i1.3865

Abstract

Tujuan dari penelitian ini adalah untuk mengamati perbedaan citra pada permukaan Thermocromic Liquid Crystal (TLC) R25C5W akibat perubahan temperatur. Metode yang digunakan untuk analisis adalah pengolahan citra berbasis morfologi matematika menggunakan perangkat lunak Matlab2013a. Citra asli yang diperoleh dalam bentuk RGB dikonversi menjadi HSV (hue, saturation, value), dengan mengambil komponen hue saja. Proses utama yang digunakan adalah opening dengan struktur elemen (SE) line. Berdasarkan analisis visual pada citra akhir hasil pengolahan citra, tampak bahwa terdapat perbedaan setiap citra untuk berbagai temperatur berdasarkan tingkat kecerahannya. Secara kuantitatif perbedaan tersebut dapat dilihat dari nilai statistiknya. Nilai max dan mean citra hue semakin meningkat seiring dengan meningkatnya temperatur.
Gait Analysis Study of Runner Using Force Plate Flaviana Catherine; Risti Suryantari
INDONESIAN JOURNAL OF APPLIED PHYSICS Vol 6, No 02 (2016): October
Publisher : Department of Physics, Sebelas Maret University

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.13057/ijap.v6i02.2394

Abstract

Humans do regular physical activities such as running. Gait is forward  propulsion of the human body using lower extremities as a thrust. Humans gait pattern is characterized by their limbs movement in terms of velocity, ground reaction force, work, kinetic energy and potential energy cycle . Human gait analysis is used to assess, to plan, and to deliver the treatment for individuals based on the conditions that affect their ability to move. Gait analysis is commonly used in running sport to improve the efficiency of athletes in running and to identify problems related to their posture or movement. The aim of this research is to do running gait analysis study of human, using force plate which equipped by track board. The benefit of this study is to provide information, ideas and new perspectives about running and its prevention over an injury. The main method that will be discussed in this study is system design of gait analysis with specific setting, hardware and software, in order to acquire data(s).
GLCM Texture Feature Selection for Alzheimer's Detection: A Combination of Statistical Tests, Decision Tree, and Random Forest Cindyawati, Cindyawati; Suryantari, Risti; Sulungbudi, Janto V.
International Journal of Artificial Intelligence Research Vol 9, No 1.1 (2025)
Publisher : Universitas Dharma Wacana

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.29099/ijair.v9i1.1.1509

Abstract

Alzheimer’s disease is a progressive neurodegenerative disorder that leads to a gradual decline in memory and cognitive function, most commonly affecting individuals over the age of 65. Early detection is essential to enable timely interventions, slow disease progression, and improve quality of life. This study aimed to identify the most dominant texture features from brain MRI images using the Gray Level Co-occurrence Matrix (GLCM) for feature extraction. The extracted features were analyzed through non-parametric statistical tests and machine learning algorithms, including Decision Tree and Random Forest, and validated with cross-validation procedures to ensure robustness. The findings revealed that contrast at 90° consistently emerged as the most significant feature, capturing vertical texture variations associated with brain atrophy, while correlation at 135° provided additional discriminatory power by representing disrupted pixel intensity relationships. In combination, these features enhanced the accuracy of classification models, outperforming other GLCM parameters. The results emphasize that careful selection of texture features improves both accuracy and stability in distinguishing between Alzheimer’s and non-Alzheimer’s brains. This study demonstrates that image-based machine learning frameworks can serve as reliable tools to support early detection of Alzheimer’s disease, offering valuable implications for clinical practice and guiding future research on efficient, non-invasive diagnostic approaches.
Aplikasi Thermochromic Liquid Crystal Untuk Mengamati Perpindahan Kalor Pada Permukaan Logam Risti Suryantari; Flaviana Flaviana
INDONESIAN JOURNAL OF APPLIED PHYSICS Vol 7, No 1 (2017): April
Publisher : Department of Physics, Sebelas Maret University

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.13057/ijap.v7i1.2292

Abstract

Tujuan penelitian ini adalah untuk mengamati peristiwa perpindahan kalor pada area permukaan logam yang bersentuhan dengan permukaan lembaran Thermochromic Liquid Crystal (TLC) R30C5W, melalui citra permukaan TLC selama proses pemanasan logam. Logam dipanaskan dengan pemanas celup, sehingga kalor akan terdistribusi hingga mencapai permukaan logam. Apabila permukaan logam tersebut bersentuhan dengan permukaan TLC, maka kalor akan berpindah dari permukaan logam ke permukaan TLC, dan ditunjukkan dengan terjadinya perubahan warna pada permukaan TLC. Citra asli yang diperoleh dalam bentuk RGB dikonversi menjadi HSV (hue, saturation, value), lalu diambil komponen hue saja, dan kemudian citra hue diproses menggunakan Matlab2014a untuk mendapatkan citra yang lebih baik. Hasil menunjukkan, seiring dengan meningkatnya temperatur permukaan logam, nilai mean hue semakin meningkat. Selain itu, nilai hue sepanjang garis tengah lingkaran pada permukaan TLC, cukup merata di bagian tengahnya (lingkaran dalam) namun semakin berkurang di tepinya (tepi kanan dan kiri), yang menunjukkan semakin jauh dari tepi permukaan logam maka energi kalornya semakin berkurang, karena terjadi perpindahan kalor pada tepi permukaan logam ke udara di sekitarnya. Kata kunci: Thermochromic Liquid Crystal (TLC), hue, perpindahan kalor.
Linearization of Hue Value on The Surface of Thermochromic Liquid Crystal With Variation of Temperature Risti Suryantari; Flaviana F
INDONESIAN JOURNAL OF APPLIED PHYSICS Vol 5, No 01 (2015): April
Publisher : Department of Physics, Sebelas Maret University

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.13057/ijap.v5i01.268

Abstract

This research has observed a linear relation of hue value on the surface of a Thermochromic Liquid Crystal (TLC), with variation of temperature, based on statistic value of hue image.  In this research we use ample of TLC with temperature range 250-300 C and 300-350 C. The original image in RGB format is converted to HSV (hue, saturation, value) and by taking hue without saturation and value, then the hue image is processed using Matlab2013a based on a mathematical morphology with opening and closing for the main process to get better images. The final image of each temperature variation can be distinguished based on the statistic value of each image. The value of max and mean hue increases by increasing temperature for each sample. Both samples tend to have the same linearization based on its mean value.
Transition Temperature in Thermochromic Liquid Crystals using Second-Order Features Extraction Cindyawati Cindyawati; Risti Suryantari
INDONESIAN JOURNAL OF APPLIED PHYSICS Vol 13, No 2 (2023): October
Publisher : Department of Physics, Sebelas Maret University

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.13057/ijap.v13i2.73552

Abstract

Liquid crystals are a type of substance that has solid and liquid properties. One of the types of it is cholesteric. Cholesteric liquid crystals have a characteristic which is called pitch. Pitch is very sensitive to changes in temperature. The pitch will reflect different colors depending on the wavelength at a particular temperature. Thermochromic Liquid Crystals (TLC) is the cholesteric liquid crystals material sold commercially. At the transitional temperature, the texture of TLC changes, so the reflected color will also change. Second-order feature extraction was chosen to determine the change in texture with the transition temperature. The TLC layer was made by thickness of 100 µm. This layer was heated and observed using a polarizing microscope with an angle between the polarizer and analyzer of 90o. The obtained result are cross patterns emerged at anisotropic transition temperature and higher temperature on TLC will lead to an isotropic phase.
The Application of Thermochromic Liquid Crystal in Temperature Distribution Measurement of Human’s Palm Hand Flaviana F; Risti Suryantari
INDONESIAN JOURNAL OF APPLIED PHYSICS Vol 5, No 01 (2015): April
Publisher : Department of Physics, Sebelas Maret University

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.13057/ijap.v5i01.272

Abstract

Temperature is one of the most important parameters that represent human’s health condition. Some conventional measurements have not been fully accurate, concise, and precise, so Thermochromic Liquid Crystal (TLC) material is required, that based on its structure of molecule characteristics has respond for alteration of local temperature that indicated by color gradation.The purpose of this research is to perform and to learn the application of TLC-based measurement system in the palm of human’s hands. The benefit of this study is the result of that subject’s temperature mapping provides some opportunities for patients with painful diabetic neuropathy, which lead to ulceration in their foot or hand. The method has been developed using TLC system based on Flaviana’s research in 2012 and with specific setting, hardware and software, in order to acquire image(s). This system utilizes an image processing method, hue of the image is used as parameter, based on mathematical morphology operation.
Co-Authors A. Rusli Cindyawati Cindyawati cindyawati, cindyawati Elok Fidiani Flaviana Flaviana Philips Nicholas Gunawidjaja Sovia Hariyani Untung Sulungbudi, Janto V.