• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.20 no.1
• /
• pp.205-210
• /
• 2020

Thanks to the shift in awareness of environmentally friendly energy and government initiatives, practical light-emitting diode(LED) lighting fixtures have emerged and are being distributed, resulting in very large energy savings. However, in actual use of LED lighting, it is possible to use it as an individual, but when using a large street light or a whole home lighting, the whole lighting system is realized due to various problems such as efficiency, stability, and reliability. Doing so has several problems. Although AC-LED has been developed recently to solve safety problems such as heat generation phenomenon of the conventional DC-LED, it also has various problems such as quality safety and reliability, which are difficult to use as outdoor lighting using existing AC Power. This happens. Accordingly, the appropriate power for AC-LED should be developed and applied, and the emergence of such LED lighting will play a role as a tool that can overcome the limitations of existing LED lighting and implement sustainable energy saving.

• Journal of the Korean Solar Energy Society
• /
• v.36 no.6
• /
• pp.37-46
• /
• 2016

In this study, long-term global illuminance data for 19 selected cities are calculated from modeled solar radiation data, AEER's TMY2. Perez model in Daysim daylight simulation tool is used for the solar radiation to illuminance conversion. And then, daylight availability in an unit office space is evaluated for the 19 cities. For this evaluation, various daylight performance indices are reviewed since static daylight performance index such as daylight factor (DF) and annual average global illuminance value is not suitable for actual performance evaluation in terms of visual comfort and light energy saving of a space. This study evaluated daylighting performance of prototypical office space module by introducing DA (daylight autonomy) and UDI (Useful Daylight Illuminance) index for major cities of Korea. Result shows that there is upto 18% of illuminance level difference with annual average global illuminance data, but if we consider useful daylight in a space the illuminance level difference among the cities are only within 5%. This means that for sustainable building design especially in daylight design, amount of annual global illuminance is not important factor even in cloudy cities. Daylight design and daylight harvesting system would return similar energy saving impact regardless of building location.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2015.08a
• /
• pp.197.1-197.1
• /
• 2015

현재 화합물 반도체 나노구조는 적외선 검출기, 레이저, 발광 다이오드, 단전자 트랜지스터, 태양전지 등과 같은 고효율 광전자 소자에서의 응용을 위해 활발한 연구가 진행 되고 있다. 특히 양자점은 3차원으로 구속되어 있는 상태 밀도를 갖고 있어 레이저 응용 시 낮은 문턱 전류 밀도, 높은 이득, 높은 열적 안정성을 기대되고 있다. 하지만 양자점의 크기가 불규칙적이고 운반자 수집의 한계로 인하여 기대 이하의 온도 안정성을 갖고 있어 이를 극복하기 위해 양자점의 크기와 운반자 수집을 제어하기 위해 다양한 방법이 연구되고 있다. 본 연구에서는 분자 선속 에피 성장법(Molecular Beam Epitaxy; MBE)과 원자 층 교대 성장법(Atomic Layer Epitaxy; ALE)으로 크기가 다른 CdTe/ZnTe 이중 양자점을 ZnTe 장벽층의 두께에 변화하면서 성장 후 광학적 특성을 연구하였다. 저온 광루미네센스 측정(Photoluminescence; PL) 측정 결과 장벽층 두께가 작아질수록 작은 양자점의 광 루미네센스의 세기가 감소하면서 큰 양자점의 세기가 증가하는 것을 관찰할 수 있었는데, 이는 장벽층 두께가 작아질수록 작은 양자점의 운반자들이 큰 양자점으로 이동되는 양이 많아지기 때문이다. 또한 장벽층 두께가 작아질수록 큰 양자점의 반치폭(Full Width at Half Maximum; FWHM)이 단층 양자점의 반치폭 보다 감소하는 것을 관찰 할 수 있었는데 이는 작은 양자점과 결합된 큰 양자점이 작은 양자점의 strain을 받아 크기의 균일함이 증가했기 때문이다. 이와 같은 결과 두 양자점이 결합된 이중 양자점 구조가 단층 양자점의 한계인 운반자 수집과 크기의 균일함을 향상할 수 있는 좋은 구조임을 제시하고 있다.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.13 no.3
• /
• pp.7-13
• /
• 1999

In this paper, a low wattage high frequency operation electronic ballast for double ended 70W metal halide lamp has been investigated As an input source of the proposed ballast, 220V, 60 Hz ac voltage is used and is converted high frequency ac voltage by power processing system. To prevent a physical destruction of the lamp from acoustic resonance phenorrenon, the proposed ballast sLWlies alternating voltage of 22kHz frequency to a metal halide lamp. It shows sorre efficacious result that reduce the start up tiIre of lamp and electric power consumption. By testing the proposed ballast, lamp voltage and lamp current are 155Vpeak, O.64A, respectively. Lamp luminous flux is 5300lm with 82W input power and ballast efficiency is 64.63 Im/w. The average starting tiIre and restriking tiIre of lamp are 3.9 and 4.5 minutes, respectively.tively.

• The Proceedings of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.11 no.4
• /
• pp.59-65
• /
• 1997

This paper proposes a new approach for the design of a multi-output electronic ballast for fluorescent lamps of different outputs and control method. At first, a standard-output electronic ballast is constructed and then fluorescent lamps with different outputs are lighted by the frequency control of inverter circuit using MeV. This multi-output electronic ballast consists of a rectifier circuit, an inverter circuit, and a frequency control circuit to determine the optimal frequency for the lamps of different output. In order to verify the proposed design method, a prototype of a multi-output electronic ballast for 11 [WJ. 15[WJ compact fluorescent lamps and 20W fluorescent lamp is constructed. Results of observing the voltage and current characteristics of lamps are in accord with those of PSpice simulation. Also its efficacy is nearly the same as the other electronic ballasts. From the result, therefore, validity of the proposed design method of a multi-output electronic ballast for fluorescent lamps is verified.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.27 no.5
• /
• pp.307-311
• /
• 2014

Because of a waveguiding effect and total internal reflection caused by a difference in refractive indices, only 20% of generated light is emitted to the air and the rest is trapped or absorbed in the device. An improvement of outcoupled efficiency of organic light-emitting diodes was studied using a microlens array. Mold of microlens array was fabricated by using photo-lithography with the AZ9260 photoresist, and the microlens array was formed onto the glass substrate using the UV curing agent named ZPU13-440. Device structure consists of microlens/glass/ITO/TPD/$Alq_3$/LiF/Al. It was found that there is an improvement of external quantum efficiency by about 20% at the same current density for the device with the microlens array compared to that of the reference one. Simulated outcoupled efficiency shows the improvement by about 20% for the device with the microlens array compared to that of the reference one. These results are consistent with the experimental ones.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2013.02a
• /
• pp.679-679
• /
• 2013

태양전지는 계속되는 유가상승과 무소음 무공해의 녹색에너지원이라는 점에서 각광받고 있다. 더욱이 발전단가가 높기 때문에 특히 저가의 다결정 실리콘 태양전지의 연구가 활발히 진행되고 있다. 태양전지의 texturing 공정은 광 포획 효과를 극대화 시킨다. 이에 따라 웨이퍼 표면에 텍스쳐를 형성하여, 광학적 손실을 줄이는데, 일반적으로 alkaline etching (WET) 공정과 reactive ion etching (RIE) 공정이 사용된다. 본 연구에서는 RIE, WET 공정을 사용하여 만든 texturing 구조의 태양전지를 모듈 공정 진행 전 특성평가를 한 후 다시 모듈 공정 후 특성평가를 진행하였다. 특성평가는 태양전지의 전류-전압 곡선을 통해 개방전압, 단락전류, 곡선인자 을 측정하고, 파장에 따른 양자효율 및 반사율을 측정하였다. 또한 태양전지의 전기에너지를 가하여 생성되는 전계발광 현상과 NIR camera를 이용하여 Grain의 Dark Area 및 Micro crack을 검출하였다. 이와 같은 모듈 공정 전/후 특성을 측정하고, 이를 비교 분석하여 BIPV 적용 시 태양전지의 동작특성을 확인하였다.

• Journal of the Korean Graphic Arts Communication Society
• /
• v.22 no.2
• /
• pp.179-198
• /
• 2004

Organic electroluminescent devices are light-emitting diodes in which the active materials consist entirely of organic materials. Recently, many fluorescent organic materials have been reported and the study on synthesis and application of new organic light-emitting materials has been demanded. This paper reports the optical and electrical characteristics of OLEDs using novel polymers containing biphenyl structure. First, Optical properties of novel light-emitting biphenyl derivatives doped with poly(9-vinyl carbazole)(PVK) and emitted blue, bluish green color, which is attributed to the overlap area between PL spectrum of host(PVK) and absorption spectra of guests(polymer). This is correspondent with F$\"{o}$rster energy transfer process in the blends. And, OLED devices were fabricated using poly (3,4-ethylenedioxy thiophene) (PEDOT) as a hole injection material and tris-(8-hydroxyquinoline) aluminum ($Alq_3$) as an electron transporting material. EL devices fabricated as ITO/PEDOT/PVK doped with biphenyl derivatives/$Alq_3$/Li:Al and I-V-L chatacteristics and emitting efficiency of EL devices were examined. Finally, the drift mobility of PVK doped with biphenyl derivatives and $Alq_3$ were measured by TOF technique varying applied electric field. EL efficiency was increased as the ratio of hole mobility of PVK doped with biphenyl derivatives and electron mobility of $Alq_3$ was close to one.

• Journal of Satellite, Information and Communications
• /
• v.9 no.1
• /
• pp.1-5
• /
• 2014

Recently, building is rapidly develop more intelligently because of the development of industries. And people seek such as comfort, efficiency, and convenience in office environment and the living environment. Also, people were able to use a variety of devices. Smart TV and smart phones were distributed widely so interaction between devices and human has been increase the interest. A various method study for interaction but there are some discomfort and limitations using controller for interaction. In this paper, a user could be easily interaction and control LED through using Kinect and gesture(hand gestures) without controller. we designed interface which is control LED using the joint information of gesture obtained from Kinect. A user could be individually controlled LED through gestures (hand movements) using the implementation of the interface. We expected developed interface would be useful in LED control and various fields.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.13 no.7
• /
• pp.3146-3151
• /
• 2012

For using them as a optical source of inspections equipment for LCD panel, the design ofexcellent backlight system, brightness uniformity and high power and good protection against heat is essential.In this paper, backlight system which is built in the 45 inch side emitting LCD backlight by LED arraystructure and driving circuit were designed and developed. After that, their performances were measured. Itshowed the luminance from 3,000 to 25,000[$cd/m^2$], the mean value x:0.3144, y:0.3076 of x-y chromaticity,dimming range of 27~515[$cd/m^2$], free flicker noise in the 80kHz and black level of 0.7~0.1[$cd/m^2$], thermaltest of cooling system in 20,000[$cd/m^2$] over values.