Hasil Pencarian  ::  Simpan CSV :: Kembali

"Dalam tugas akhir ini telah dirancang dan dibuat suatu sistem untuk mengukur besarnya intensitas cahaya tampak (visible light). Sistem tersebut berbasis pada mikrokontroler sebagai pengolah data. Selanjutnya hasil pengukuran ditampilkan pada sebuah layar LCD. Untuk dapat mengetahui informasi mengenai intensitas cahaya, maka dibutuhkan suatu sistem perangkat keras pengukuran yang dilengkapi dengan perangkat lunak. Perangkat keras yang digunakan yaitu rangkaian sensor cahaya LDR (Light Dependent Resistor) untuk mendeteksi intensitas cahaya, kemudian mengkonversikannya menjadi tegangan. Rangkaian ADC (Analog to Digital Converter) untuk mengubah tegangan analog yang berasal dari rangkaian sensor cahaya, untuk menjadi data pengukuran digital. Sistem mikrokontroler untuk mengolah dan mengkalibrasi data hasil pengukuran tersebut untuk ditampilkan di layar LCD (Liquid Crystal Display). Karena keterbatasan tidak tersedianya monokromator, maka tidak dapat dilaksanakan pengukuran panjang gelombang sinar yang diamati. Selanjutnya, untuk mempermudah pengukuran intensitas cahaya, dikelompokan dalam beberapa warna yaitu cahaya putih, merah, kuning, hijau, dan biru. Untuk mendekati nilai yang sebenarnya telah dilakukan kalibrasi untuk masing-masing warna sesuai dengan spektrum sensitivitas LDR.

---

An instrument prototype for visible light intensity measurement has been designed and fabricated for the purpose of final project to obtain Sarjana Teknik degree of Electrical Engineering, Universitas Indonesia. The instrument is mainly supported by microcontroller AT89S52 system as the measurement data processing center. Further more, the result of the measurement processing is displayed on LCD screen.

To obtain the light intensity measurement data, it is required an instrument system which consists of microcontroller system, light dependent resistor (LDR) circuit to detect light intensity and convert it to analog voltage, and analog to digital converter (ADC) to convert the analog voltage from LDR circuit to be digital measured data for microcontroller. Furthermore, the microcontroller will process and calibrate the measurement data and diplays the data to the ouput screen.

Due to limited facilities, for example unavailability of monochromator, the wavelength measurement cannot be conducted. Moreover, to simplify the light intensity measurement for specific color light, the light is grouped into several groups of color such as white, red, yellow, green and blue. To obtain a better accuracy, it has been done intensity callibatrion for every group of color according to LDR sensitivity spectrum and the callibration data is used in microcontroller system to determine accurate measurement data."

"Tujuan penelitian ini untuk mengetahui pengaruh penggunaan sumber sinar berbeda terhadap kekuatan tarik diametral resin komposit bulk-fill. Resin komposit bulk-fill Tetric N-Ceram Bulk Fill dibuat sebanyak 20 spesimen berbentuk lempeng dengan diameter 6 mm dan tebal 3 mm. Spesimen dibagi menjadi dua kelompok yaitu kelompok yang disinari dengan sumber sinar QTH dan sumber sinar LED. Uji kekuatan tarik diametral dilakukan dengan menggunakan Universal Testing Machine. Hasil penelitian menunjukkan nilai rerata kekuatan tarik diametral resin komposit bulk-fill yang disinari sumber sinar QTH dan LED sebesar 38.62 2.34 dan 42.02 3.21. Hasil uji independent sample T menunjukkan nilai rerata pada kedua kelompok berbeda bermakna.

---

This study aimed to evaluate the effect of using different light sources on the diametral tensile strength of bulk fill resin composite. Bulk fill resin composite Tetric N Ceram Bulk Fill was used to make of 20 disc shape specimens with 6 mm in diameter and 3 mm in thickness. Specimens were divided into two groups, the two groups were polymerized with using QTH and LED light source curing unit. Diametral tensile strength test was conducted by using a Universal Testing Machine Shimadzu, Japan. The results showed that diametral tensile strength mean value of bulk fill resin composite that were cured with QTH and LED light source were 38.62 2.34 and 42.02 3.21 MPa respectively. Independent sample t test results showed that the mean value of the two groups was significantly different."

"Comprehensive in scope, this book covers the latest progresses of theories, technologies and applications of LEDs based on III-V semiconductor materials, such as basic material physics, key device issues (homoepitaxy and heteroepitaxy of the materials on different substrates, quantum efficiency and novel structures, and more), packaging, and system integration. The authors describe the latest developments of LEDs with spectra coverage from ultra-violet (UV) to the entire visible light wavelength. The major aspects of LEDs, such as material growth, chip structure, packaging, and reliability are covered, as well as emerging and novel applications beyond the general and conventional lightings. This book, written by leading authorities in the field, is indispensable reading for researchers and students working with semiconductors, optoelectronics, and optics.- Addresses novel LED applications such as LEDs for healthcare and wellbeing, horticulture, and animal breeding; - Editor and chapter authors are global leading experts from the scientific and industry communities, and their latest research findings and achievements are included;- Foreword by Hiroshi Amano, one of the 2014 winners of the Nobel Prize in Physics for his work on light-emitting diodes."

"ABSTRACTThe molecular weight of Polymer material can be determined using optical system by measuring the intensity of scattered light at low angle light scattering and its the incident beam, based on Rayleigh scattering have developed by Debye has known as Static Light Scattering. To carry out this measurement, an optical system was constructed using a HeNe laser light with a certain intensity, and the light passed through a polymer solution and its scattered light were then detected using a photo multiplier. To obtain the experimental results, the set-up was tested using a polymer standard, which has been already known its average molecular weight. In this experiment were used the polymer standard with average molecular weight 35000, 110000 and 200000. Furthermore, this optical experiment set-up constant, were used for determining the average molecular weight of the polymer samples. In this experiment a linear curve relation between the optical Rayleigh polymer and the polymer concentrations was constructed, and by extrapolating this linear curve up to zero concentration the molecular weight of polymer can be determined. From the laboratory test we got that the experimental set up could be used for the measurement of polymer, which has the molecular weight larger than 35000 to 200000, with tolerance 4 percent."

"An optical modulation by the use of bending effect developed from the effect of relative bending loss on optical fiber. The bending loss will decrease if the bending angle decreases. By varying the bending angle the bending loss will vary too. The modulation process obtained through this mechanism. The bending angle on optical fiber obtained from three mandrel laid on the loud-speaker; two mandrel on the frame and one on the cone of loud-speaker, while optical fiber laid between the mandrel. If current signal injected on coil loudspeaker, the coil will push the mandrel and then push optical fiber to form bending angle. The obtained 3 dB frequency response ranged from 28 Hz to 5714.3 Hz while the SNR and modulation index are 32.98 dB and 0.956 respectively. This modulator would be useable for single channel instrumentation and control links."