Jung Min Hwang - Academia.edu (original) (raw)

Papers by Jung Min Hwang

Journal of Photonics for Energy, 2015

This paper presents a "hybrid" structure for the coating of yellow YAG∶Ce3 þ phosphor on blue GaN... more This paper presents a "hybrid" structure for the coating of yellow YAG∶Ce3 þ phosphor on blue GaN-based light-emitting diodes (LEDs). The luminous efficiency of the hybrid phosphor structure improved by 5.9% and 11.7%, compared with the conventional remote and conformal phosphor structures, respectively, because of the increased intensity of the yellow component. The hybrid structure also has an advantage in the phosphor usage reduction for the LEDs. Furthermore, the electric intensity of the hybrid phosphor structure was calculated for various thicknesses by conducting TFCalc32 simulation, and the enhanced utilization of blue rays was verified. Finally, the experimental results were consistent with the simulation results performed using the Monte-Carlo method.

Journal of Photonics for Energy, Feb 19, 2015

This paper presents a "hybrid" structure for the coating of yellow YAG∶Ce3 þ phosphor on blue GaN... more This paper presents a "hybrid" structure for the coating of yellow YAG∶Ce3 þ phosphor on blue GaN-based light-emitting diodes (LEDs). The luminous efficiency of the hybrid phosphor structure improved by 5.9% and 11.7%, compared with the conventional remote and conformal phosphor structures, respectively, because of the increased intensity of the yellow component. The hybrid structure also has an advantage in the phosphor usage reduction for the LEDs. Furthermore, the electric intensity of the hybrid phosphor structure was calculated for various thicknesses by conducting TFCalc32 simulation, and the enhanced utilization of blue rays was verified. Finally, the experimental results were consistent with the simulation results performed using the Monte-Carlo method.

2015 IEEE International Conference on Consumer Electronics - Taiwan, 2015

A high cost-performance ratio LED bulb and wireless TRIAC controller are proposed in this paper. ... more A high cost-performance ratio LED bulb and wireless TRIAC controller are proposed in this paper. The core circuit of LED bulb is AC step driver which is using driver-onboard technology, it has the advantages of higher reliability, lower cost and compact size. This AC step driver can be dimmed by TRIAC, for smart lighting application, the wireless TRIAC controller is designed. This controller which is universal design not only can control the LED bulbs, but also can dim the tungsten lamps. Users can use the mobile device to dim the common lamps in indoor lighting. In the future, when the sensors are built in the building, it can link the smart lighting easily.

SPIE Proceedings, 2016

In this study, we propose a fast rebuild technology for evaluating light quality in large areas. ... more In this study, we propose a fast rebuild technology for evaluating light quality in large areas. Outdoor light quality, which is measured by illuminance uniformity and the color rendering index, is difficult to conform after improvement. We develop an algorithm for a lighting quality mapping system and coordinates using a micro spectrometer and GPS tracker integrated with a quadcopter or unmanned aerial vehicle. After cruising at a constant altitude, lighting quality data is transmitted and immediately mapped to evaluate the light quality in a large area.

2015 IEEE International Conference on Consumer Electronics - Taiwan, 2015

In this paper, a prototype of AC LED light engine is implemented. This light engine is highly des... more In this paper, a prototype of AC LED light engine is implemented. This light engine is highly designed and integrated with different fields, including optical, mechanical, electrical part, control system, and safety requirement. Our light engine can directly install in different lighting fixtures like down light or spot light, which is very convenient and cost-saving for luminaries manufactures. It also can offer customized solutions about CCT, beam angle, even involved intelligent control system in the future. The specification of light engine is that the CCT is 4601K, CRI is 81, and the lm/W is 102 at 10W input power.

2015 International Conference on Numerical Simulation of Optoelectronic Devices (NUSOD), 2015

In this paper, the algorithm for the stepless tunable four-chip LED on the black body radiation c... more In this paper, the algorithm for the stepless tunable four-chip LED on the black body radiation curve, using the Generalized Reduced Gradient method, is proposed. The lumen outputs of four-chip LED, for color temperatures between 2500K and 6500K, are then calculated in real-time, without using a lookup table, and for high quality lighting design.

Journal of Light & Visual Environment, 2013

The LED lighting fixture has the versatile advantages including energy saving, long life time, co... more The LED lighting fixture has the versatile advantages including energy saving, long life time, compact size, wide color range and easy dimming comparing with fluorescent lamp. Adjusting the color temperature of LED dynamic lighting fixture becomes an interesting application in interior lighting or sun light simulation. In this paper, the different types of LED (AC, HV, DC) for the dynamic lighting fixture are evaluated.

SPIE Proceedings, 2013

ABSTRACT In this study, a process for optimizing the color temperature and lighting distribution ... more ABSTRACT In this study, a process for optimizing the color temperature and lighting distribution on indoor LED lighting for human factor and energy saving is proposed. Based on the features of LED lighting, the diversified fixture design is more possibilities, such as the fixture with color-temperature and lighting distribution tunable. Therefore, the generalized reduced gradient optimization method is used to calculate the corrected color temperature of the fixture for the seat near the window affected by sun light. This research result could be used in the LED lighting design for more energy saving

Journal of Solid State Lighting, 2014

This study demonstrates the hybrid structure with high lumen efficiency and uniform angular-depen... more This study demonstrates the hybrid structure with high lumen efficiency and uniform angular-dependent correlated color temperature (CCT) for warm white LED. Compared to the conventional structures, the hybrid structure combines the advantage of the two different fabrication methods including dispense and pulse spray method together, which can produce the high quality lighting source. The experimental results indicate that the hybrid structure yielded higher lumen efficiency than conventional phosphor structure because of the gradual refractive index difference from the coating layer to the dispense layer. Moreover, the CCT deviations of the hybrid phosphor structure could be reduced to 65 K in range of −70 to 70 degrees. This is attributed to the uniform color mixing of the blue, yellow and red band in the hybrid phosphor structure. In addition, the chromaticity coordinate shift compared to the hybrid structure with the dispense structure are almost the same at a current regulation from 20 mA to 500 mA. We believe that the technology of the hybrid structure with high lumen efficiency and uniform angular-dependent CCT is suitable for in the general lighting application.

2015 IEEE International Conference on Consumer Electronics - Taiwan, 2015

This paper presents a universal wireless controller for PWM, Analog and TRIAC dimming. The presen... more This paper presents a universal wireless controller for PWM, Analog and TRIAC dimming. The presented dimming control system is a universal controller which was based on the Bluetooth wireless network. The universal controller was designed by the algorithm which is compatible with Analog (0-10V), Pulse Width Modulation (PWM) and TRIAC dimming control interface. Therefore, there is no compatible problem with the new lamps. The control system integrated with microcontroller, bluetooth module, power module and TRIAC module. Users can use the mobile devices to control the lighting. It not only can control the commercially lamps, but also can achieve the wireless smart lighting controlled.

Optical and Quantum Electronics, 2016

Journal of Photonics for Energy, 2015

This paper presents a "hybrid" structure for the coating of yellow YAG∶Ce3 þ phosphor on blue GaN... more This paper presents a "hybrid" structure for the coating of yellow YAG∶Ce3 þ phosphor on blue GaN-based light-emitting diodes (LEDs). The luminous efficiency of the hybrid phosphor structure improved by 5.9% and 11.7%, compared with the conventional remote and conformal phosphor structures, respectively, because of the increased intensity of the yellow component. The hybrid structure also has an advantage in the phosphor usage reduction for the LEDs. Furthermore, the electric intensity of the hybrid phosphor structure was calculated for various thicknesses by conducting TFCalc32 simulation, and the enhanced utilization of blue rays was verified. Finally, the experimental results were consistent with the simulation results performed using the Monte-Carlo method.

Journal of Photonics for Energy, Feb 19, 2015

This paper presents a "hybrid" structure for the coating of yellow YAG∶Ce3 þ phosphor on blue GaN... more This paper presents a "hybrid" structure for the coating of yellow YAG∶Ce3 þ phosphor on blue GaN-based light-emitting diodes (LEDs). The luminous efficiency of the hybrid phosphor structure improved by 5.9% and 11.7%, compared with the conventional remote and conformal phosphor structures, respectively, because of the increased intensity of the yellow component. The hybrid structure also has an advantage in the phosphor usage reduction for the LEDs. Furthermore, the electric intensity of the hybrid phosphor structure was calculated for various thicknesses by conducting TFCalc32 simulation, and the enhanced utilization of blue rays was verified. Finally, the experimental results were consistent with the simulation results performed using the Monte-Carlo method.

2015 IEEE International Conference on Consumer Electronics - Taiwan, 2015

A high cost-performance ratio LED bulb and wireless TRIAC controller are proposed in this paper. ... more A high cost-performance ratio LED bulb and wireless TRIAC controller are proposed in this paper. The core circuit of LED bulb is AC step driver which is using driver-onboard technology, it has the advantages of higher reliability, lower cost and compact size. This AC step driver can be dimmed by TRIAC, for smart lighting application, the wireless TRIAC controller is designed. This controller which is universal design not only can control the LED bulbs, but also can dim the tungsten lamps. Users can use the mobile device to dim the common lamps in indoor lighting. In the future, when the sensors are built in the building, it can link the smart lighting easily.

SPIE Proceedings, 2016

In this study, we propose a fast rebuild technology for evaluating light quality in large areas. ... more In this study, we propose a fast rebuild technology for evaluating light quality in large areas. Outdoor light quality, which is measured by illuminance uniformity and the color rendering index, is difficult to conform after improvement. We develop an algorithm for a lighting quality mapping system and coordinates using a micro spectrometer and GPS tracker integrated with a quadcopter or unmanned aerial vehicle. After cruising at a constant altitude, lighting quality data is transmitted and immediately mapped to evaluate the light quality in a large area.

2015 IEEE International Conference on Consumer Electronics - Taiwan, 2015

In this paper, a prototype of AC LED light engine is implemented. This light engine is highly des... more In this paper, a prototype of AC LED light engine is implemented. This light engine is highly designed and integrated with different fields, including optical, mechanical, electrical part, control system, and safety requirement. Our light engine can directly install in different lighting fixtures like down light or spot light, which is very convenient and cost-saving for luminaries manufactures. It also can offer customized solutions about CCT, beam angle, even involved intelligent control system in the future. The specification of light engine is that the CCT is 4601K, CRI is 81, and the lm/W is 102 at 10W input power.

2015 International Conference on Numerical Simulation of Optoelectronic Devices (NUSOD), 2015

In this paper, the algorithm for the stepless tunable four-chip LED on the black body radiation c... more In this paper, the algorithm for the stepless tunable four-chip LED on the black body radiation curve, using the Generalized Reduced Gradient method, is proposed. The lumen outputs of four-chip LED, for color temperatures between 2500K and 6500K, are then calculated in real-time, without using a lookup table, and for high quality lighting design.

Journal of Light & Visual Environment, 2013

The LED lighting fixture has the versatile advantages including energy saving, long life time, co... more The LED lighting fixture has the versatile advantages including energy saving, long life time, compact size, wide color range and easy dimming comparing with fluorescent lamp. Adjusting the color temperature of LED dynamic lighting fixture becomes an interesting application in interior lighting or sun light simulation. In this paper, the different types of LED (AC, HV, DC) for the dynamic lighting fixture are evaluated.

SPIE Proceedings, 2013

ABSTRACT In this study, a process for optimizing the color temperature and lighting distribution ... more ABSTRACT In this study, a process for optimizing the color temperature and lighting distribution on indoor LED lighting for human factor and energy saving is proposed. Based on the features of LED lighting, the diversified fixture design is more possibilities, such as the fixture with color-temperature and lighting distribution tunable. Therefore, the generalized reduced gradient optimization method is used to calculate the corrected color temperature of the fixture for the seat near the window affected by sun light. This research result could be used in the LED lighting design for more energy saving

Journal of Solid State Lighting, 2014

This study demonstrates the hybrid structure with high lumen efficiency and uniform angular-depen... more This study demonstrates the hybrid structure with high lumen efficiency and uniform angular-dependent correlated color temperature (CCT) for warm white LED. Compared to the conventional structures, the hybrid structure combines the advantage of the two different fabrication methods including dispense and pulse spray method together, which can produce the high quality lighting source. The experimental results indicate that the hybrid structure yielded higher lumen efficiency than conventional phosphor structure because of the gradual refractive index difference from the coating layer to the dispense layer. Moreover, the CCT deviations of the hybrid phosphor structure could be reduced to 65 K in range of −70 to 70 degrees. This is attributed to the uniform color mixing of the blue, yellow and red band in the hybrid phosphor structure. In addition, the chromaticity coordinate shift compared to the hybrid structure with the dispense structure are almost the same at a current regulation from 20 mA to 500 mA. We believe that the technology of the hybrid structure with high lumen efficiency and uniform angular-dependent CCT is suitable for in the general lighting application.

2015 IEEE International Conference on Consumer Electronics - Taiwan, 2015

This paper presents a universal wireless controller for PWM, Analog and TRIAC dimming. The presen... more This paper presents a universal wireless controller for PWM, Analog and TRIAC dimming. The presented dimming control system is a universal controller which was based on the Bluetooth wireless network. The universal controller was designed by the algorithm which is compatible with Analog (0-10V), Pulse Width Modulation (PWM) and TRIAC dimming control interface. Therefore, there is no compatible problem with the new lamps. The control system integrated with microcontroller, bluetooth module, power module and TRIAC module. Users can use the mobile devices to control the lighting. It not only can control the commercially lamps, but also can achieve the wireless smart lighting controlled.

Optical and Quantum Electronics, 2016