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DEVELOPMENT AND EXPERIMENTAL CHARACTERIZATION OF AN IOT-CONTROLLED RGB LED LIGHTING SYSTEM FOR HYDROPONIC APPLICATIONS
(2026-01-01)
Worsoongnern, S.
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Yindeesuk, W.
;
Kamoldilok, S.
;
Srinuanjan, K.
;
Limsuwan, P.
This study presents the development of an Internet of Things-based RGB LED lighting system for precise, flexible light control in hydroponic plants. The system consists of 480 high-power RGB LEDs controlled by an ESP8266 microcontroller, enabling real-time adjustment of light intensity, photoperiod, and color ratios via a smartphone. Pulse-width modulation duty-cycle modulation enables the generation of white light suitable for different stages of plant growth. Experimental results show a linear correlation between illuminance and duty cycle for all color channels. Spectral analysis confirms stable emission within the photosynthetically active radiation range (400–700 nm), with the spectral composition remaining unchanged even when brightness is reduced (dimming). The system demonstrates high control accuracy and adaptability for regulating plant growth lighting, particularly for leafy vegetables such as lettuce.
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Effect of SILAR Techniques on Photovoltaic Properties of PbS Quantum Dot Sensitized Solar Cells
(2018-12-19)
Yindeesuk, W.
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Tusamalee, P.
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Liu, F.
;
Toyoda, T.
;
Shen, Q.
PbS quantum dots (QDs) have been received attention as a photosensitizer for quantum dot sensitized solar cells (QDSSCs) due to their narrow band gaps, quantum size effect, and multiple exciton generation (MEG). In this work, we prepared PbS QDSSCs by successive ionic layer adsorption and reaction method (SILAR) with PbS QDs deposited onto titanium dioxide (TiO <inf>2</inf> ), then the PbS QDs have been investigated the effect of SILAR cycles on photovoltaic properties. The power conversion efficiency (PCE) of the solar cells is dependent on SILAR cycles and an optimal SILAR cycle is two cycles. The PbS QDSSCs achieve the PCE of 1.79% with the photocurrent of 16.39 mA/cm <sup>-2</sup> . Moreover, the optical properties were investigated by UV-visible absorption spectroscopy, which reveals a SILAR cycle affecting a band gap of PbS QDs.
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Backward Third-Harmonic Pulse Generation in a One-Dimensional PIM/NIM Structure
(2018-12-19)
Buranasiri, P.
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Wicharn, S.
;
Yindeesuk, W.
In this work, a set of couple-mode equations for describing a backward third harmonic generation (BTHG) in a one-dimensional periodic structure of positive-index material (PIM) layers and third-order nonlinear negative-index material (NIM) layers was analysed using multiple-scale method. Due to the negative-index phase matching and band-edge field enhancement the intensities of backward third-harmonic pulsed generated from the PIM/NIM periodic structure is increased for 100 time of those generated from a single NIM medium.
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Optical properties of Mn-doped CdS thin films grown by the SILAR method
(2018-12-19)
Phasook, N.
;
Kamoldirok, S.
;
Yindeesuk, W.
In this research, the manganese doped cadmium sulfide (Mn-doped CdS) thin films were synthesized on glass substrates using successive ionic layer adsorption and reaction (SILAR) method. The thin films were prepared by different mixing percentage of manganese with cadmium sulfide precursors in the range of 1 - 20 mole%. The optical properties were investigated by ultraviolet-visible spectrophotometer. The morphology and elemental analysis were measured by scanning electron microscopy (SEM) and energy dispersive x-ray spectroscopy (EDS), respectively.
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Study of structural and optical properties of PbS thin films
(2018-01-01)
Homraruen, T.
;
Sudswasd, Y.
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Sorod, R.
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Kayunkid, N.
;
Yindeesuk, W.
This research aimed to synthesize lead sulfide (PbS) thin films on glass slides using the successive ion layer absorption and reaction (SILAR) method. We studied the optical properties and structure of PbS thin films by changing the number of dipping cycles and the concentration of precursor solution. The results of this experiment show that different conditions have a considerable influence on the thickness and absorbance of the films. When the number of dipping cycles and the concentration of the solution are increased, film thickness and absorbance tend to become higher. The xrays diffraction pattern showed all the diffraction peaks which confirmed the face center cubic and the structure of PbS had identified. Grain size computation was used to confirm how much these conditions could be affected.
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Digital holography system for undergraduate student laboratory
(2015-01-01)
Buranasiri, P.
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Plaipichit, S.
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Yindeesuk, W.
;
Yoshimori, K.
In this paper, we discuss the digital holography (DH) experiment in our optical and communication laboratory course for undergraduate students at Physics department, KMITL. The purposes of DH experiment are presenting our students the meaning and advantage of DH and its applications. The Gabor configurations of in-line DH has been set up for recording a number of samples, which were placed on different distances, simultaneously. Then, the images of all objects have been numerical reconstructed by using computer. The students have been learned that all of reconstructed images have been got from only one time recording, while using the conventional recording technique, sharp images of different objects have been gotten from different recording time. The students also have been learned how to use DH technique for investigation some different kinds of samples on their own of interested such as a human hair or a fingerprint. In our future work, our DH system will be developed to be a portable apparatus for easily showing to children in different areas.
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Imaging enhancement of digital holography using photorefractive effect
(2015-01-01)
Sidakum, K.
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Buranasiri, P.
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Plaipichit, S.
;
Yindeesuk, W.
;
Yoshimori, K.
In this research, two-wave coupling in photorefractive lithium niobate crystal has been used to do imaging enhancement of digital holography (DH) system. The image bearing beam of in-line DH system has been incident and interfered with a reference beam that was emerged from the same laser on a LiNbO<inf>3</inf> crystal. With certain angles between both beams, the energy of the reference beam was transferred to the image bearing beam then resulted the enhancement of the reconstructed image of the DH system. By using the suitable intensity of laser beam with a right PR crystal, the image from an in-line DH imaging system would be improved.
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Temperature dependent photoluminescence of ZnSe/Alq3 hybrid heterostructure
(2008-12-01)
Pecharapa, W.
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Potirak, P.
;
Yindeesuk, W.
II-VI inorganic/organic heterostructures consisting of ZnSe and tris(8-hydroxyquinoline) aluminum (Alq<inf>3</inf>) were prepared by electron beam evaporator. Alq<inf>3</inf> layer with 20 nm was grown between 200-nm ZnSe layers. Photoluminescence measurement was conducted at various temperatures in order to investigate the important temperature-dependent parameters of this structure. PL spectra revealed thermal population of exciton state and the change in PL quantum efficiency of the film. © 2008 Trans Tech Publications, Switzerland.
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Electroreflectance and photocurrent measurement of ZnSe/Alq 3/TPD heterostructure on Si-substrate
(2005-11-20)
Pecharapa, W.
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Keawprajak, A.
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Kayunkid, N.
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Rahong, S.
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Yindeesuk, W.
The optical transition energy in ZnSe/tris(8-hydroxyquinoline) aluminum (Alq<inf>3</inf>)/N,N′-bis(3-methylphenyl)-N,N′-diphenyl-benzidine (TPD) heterostructure were investigated by room-temperature electroreflectance (ER) and photocurrent (PC) measurements. PC signal showed wavelength response of the device in the range of 450-1100 nm. ER features due to optical transition energy of the single quantum well of this structure were observed. The transition energies were determined by fitting the ER spectra to the theoretical line-shape expression. The subband transition energy decreased with increasing well thickness. Under applied voltage, both ER signals show significant shift due to the quantum confined Stark effect. © 2005 Elsevier B.V. All rights reserved.
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Observation of optical transition energy in ZnSe/tris(8-hydroxyquinoline) aluminum (Alq3)/ZnSe single quantum wells by photoreflectance spectroscopy
(2004-03-01)
Nukeaw, J.
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Upprakhot, K.
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Rahong, S.
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Tunhoo, B.
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Yindeesuk, W.
The optical transition energy in ZnSe/tris(8-hydroxyquinoline) aluminum (Alq3)/ZnSe single quantum wells (SQW) thin films with well thickness from 5 to 50 nm was investigated by room-temperature photoreflectance (PR) measurements. PR features due to optical transition energy were observed in the SQWs of well thicknesses. The transition energies were determined by fitting the PR spectra to the theoretical line-shape expression. The transition energy decreased with increasing well thickness. © 2003 Elsevier B.V. All rights reserved.

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