• Design & Manufacturing
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• 제2권2호
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• pp.29-32
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• 2008

A back light unit (BLU) is a key module of a thin film transistor liquid crystal display (TFT-LCD), frequently utilized in various mobile displays. In this study, we experimentally characterize transcription and optical properties of concave and convex microlens arrays (MLAs) of light guide plate (LGP) fabricated by injection molding with polycarbonate as a LGP substrate material. Nickel mold inserts were manufactured by electroforming on the MLA which was fabricated by the thermal reflow of photoresist microstructures patterned by UV-photolithography. For the case of convex microlens, the height of replicated microlens was less than that of the mold insert while maintaining almost the same microlens diameter of the mold insert as the location of the microlens is far from the gate. In contrast, for the concave microlens, the diameter of replicated microlens was larger than that of mold insert, while showing almost the same microlens height as the mold insert. From the optical examination of replicated convex and concave MLAs, it was found that a higher luminance of the LGP was achieved by the concave MLAs compared to the convex MLAs (about 30% enhancement in this case)due to the utilization of a larger amount of light provided by the light sources.

• 한국광학회지
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• 제21권6호
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• pp.225-229
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• 2010

레이저로 가공된 평면산란패턴을 가지는 도광판은 도광판 상부로 방출되는 광이 광원과 가까운 부분에 편중되는 문제로 인해서 전체적인 휘도 분포가 균일하지 않은 문제점을 가지고 있었다. 이를 해결하기 위해 도광판 후면에 레이저를 이용하여 도광판 내부에서 특징적인 기울기를 가지는 산란패턴을 만듬으로써 도광판 상부로 방출되는 광의 균일도를 향상시키고자 하였다. 본 논문에서는 도광판 후면의 산란패턴을 간격과 가공 깊이를 다르게 조절하여 설계하고 이에 따른 도광판의 성능의 차이점을 가공전에 분석하고자 전산모사를 수행하였다. 본 논문에서 제안한 산란패턴을 가지는 도광판은 기존의 도광판의 휘도와 균일도에 비해 높은 향상을 가질 것으로 예상되는 바이다.

• 한국결정성장학회지
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• 제23권5호
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• pp.218-223
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• 2013

본 연구에서는 LCD 또는 LED를 이용한 디스플레이 장치의 BLU 반사판으로 사용할 목적으로 무전해도금에 의하여 플라스틱 기판위에 성장되어진 은 나노코팅의 반사율 특성을 조사하였다. 은 나노코팅의 미세구조는 아주 미세한 나노크기의 은 결정들로 이루어진 다결정 나노코팅인 것을 확인할 수 있었으며 코팅 층의 두께가 증가함에 따라 환원, 석출된 은 나노결정입자의 크기도 비례하여 증가되었다. 은 나노코팅의 두께가 증가함에 따라 가시광선 영역의 반사율이 감소하였으며 파장이 짧을수록 반사율의 감소가 더 심하였다. 나노코팅의 두께 증가에 따른 반사율의 감소는 환원 석출된 은나노결정의 크기와 밀접하게 관련된 것으로 은 결정입자가 클수록 요철의 정도가 심하여 반사율이 감소하는 것으로 생각되어진다. 그래서 가능한 미세한 은 나노결정을 환원, 석출시키고 코팅두께를 얇게 하는 것이 반사율 관점에서 바람직한 것으로 판단되어진다.

• Journal of Microbiology and Biotechnology
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• 제18권1호
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• pp.59-62
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• 2008

The peptide methionine sulfoxide reductases (Msrs) are enzymes that catalyze the reduction of methionine sulfoxide back to methionine. Because of two enantiomers of methionine sulfoxide (S and R forms), this reduction reaction is carried out by two structurally unrelated classes of enzymes, MsrA (E.C. 1.8.4.11) and MsrB (E.C. 1.8.4.12). Whereas MsrA has been well characterized structurally and functionally, little information on MsrB is available. The recombinant MsrB from Bacillus subtilis has been purified and crystallized by the hanging-drop vapor-diffusion method, and the functional and structural features of MsrB have been elucidated. The crystals belong to the trigonal space group P3, with unit-cell parameters a=b=136.096, $c=61.918{\AA}$, and diffracted to $2.5{\AA}$ resolution using a synchrotron-radiation source at Pohang Light Source. The asymmetric unit contains six subunits of MsrB with a crystal volume per protein mass $(V_M)\;of\;3.37{\AA}^3\;Da^{-1}$ and a solvent content of 63.5%.

• Transactions on Electrical and Electronic Materials
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• 제8권6호
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• pp.268-273
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• 2007

In this study, It was studied about the luminance characteristics of 17 inch direct-type back light using EEFL(external electrode fluorescent lamp) and CCFL(cold cathode fluorescent lamp). The EEFL has a long life time because the electrode is installed outside of lamp. And it is produced in lower price than conventional CCFL. Moreover, it does not need process of installing internal electrode. However, the EEFL technology has several problems such as difficulty of designing driving inverter and preventing this phenomenon along the skin of lamps. We suggested two types of backlight unit for LCD TV application using the EEFL and the CCFL. We found optimized optical design parameters. We set the optical variation parameters such as lamp height, lamp distance, total thickness, and angles of inner walls. We achieved 7580 nits of center luminance, 82% of luminance uniformity by using 20 lamps of the EEFL and 7297 nits of center luminance, 78% of luminance uniformity by using 16 lamps of the CCFL.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2007년도 하계학술대회 논문집 Vol.8
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• pp.428-428
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• 2007

In this study, It was studied about the luminance characteristics of 17inch direct-type back light using EEFL(External Electrode Fluorescent Lamp). EEFI has a long life time because the electrode is installed outside of lamp. And it is produced low price than conventional CCFL. It does not need process of installing internal electrode. But EEFL technology has several problems such as difficulty of design driving inverter, and prevents leckage current along the skin of lamps. Therefore, by the optimizing of inverter properties, 7525 nit center luminance was acquired in almost same power consumption condition. It was almost same luminance in CCFL backlight unit. And it was operated stably in low operating temperature such as the value of $40^{\circ}C$, so that it was adopted in conventional LCD-TV application.

• 한국재료학회지
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• 제19권1호
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• pp.7-12
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• 2009

TFT-LCD is the most popular type of flat display panel in the information technology field. The back light unit is a main part of the structure of a TFT-LCD panel. Occasionally, studies have shown that failures of the CCFL of the BLU occur due to the poor weld characteristics of these materials. The aim of this study was to prepare some technical data and to characterize a microjoined electrode for the CCFL. Microstructure examinations, microhardness measurements, resistance measurements and microtensile tests of the microjoined electrode were carried out. The result indicates that a large amount of grain coarsening exists in the heat-affected zone (HAZ) of the weld between the cup and the pin. This grain coarsening of the HAZ between the cup and pin is caused by the welding cycle, which may have an influence on the lowest microhardness values. Fracturing of the microjoined electrode also occurred at the HAZ close to the cup between the weld holding the cup and the pin. Additionally, no specific changes of the electrical resistance among the cup, pin, and lead wire themselves or in the microjoined electrode were observed.

• 대한화장품학회지
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• 제17권1호
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• pp.1-17
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• 1991

Multiport-600 Solar SimulatorR is one of the most recent and convenient in-strument for evaluation of sun protection factor(SPF). In this study, we examined the practicability of the SPF determining system using Multiport -600 and the effects of several factors-light sources, seasons and experimental animals-on the minimal erythema dose(MED) and SPF. We also tested the UV sensitivity according to the sites of Korean people, And the ultraviolet radiation reaching the earth's surface In Seoul have been observed for one year. As a result of this study, the determinig system for SPF using Multiport-600 was proved to be a good system in accuracy and time-saving. The biological activity of fluorescence UV lamp of PUVA-800R was significantly higher than natural light or solar simulator with Xe arc lamp, and the determined MED became lower in inverse proportion to room temperature rise. Skin sensitivity by ultraviolet adiation was hights. in order \circled1 back \circled2 inns, upper arm \circled3 outer upper arm \circled4 foream. We also observed that UV radiation intensity was highest at noon in july and 1 sun burn unit(MED) was 28 minutes at that time.

• 한국전기전자재료학회논문지
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• 제22권5호
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• pp.431-435
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• 2009

The apparatus has been fabricated using the laser diode and microprocessor unit. The apparatus used a InGaAlP laser diode for laser medical therapy and was designed for a pulse width modulation type to increase stimulation effects. To raise the stimulus effect of the human body, the optical irradiation frequency could be set up. The study has executed in-vivo experiment by employing our own developed laser diode irradiation system to investigate the effects of the InGaAlP laser diode irradiation on the wound healing as a preliminary study aimed at the application of InGaAlP laser diode to wound healing of human skin injury. The study cut out whole skin layers of Sprague-Dawley rat on the back part in 1 cm circle and observed developing effects after executing light irradiation for 9 days, and in result it is found that the light irradiation rat showed earlier wound healing than non-irradiation rat during the experimental period. In addition, there are some differences found regarding the healing process between laser diode irradiated rats and non-irradiated ones.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2010년도 제39회 하계학술대회 초록집
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• pp.127-127
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• 2010

최근 Light-emitting diodes (LEDs: 발광다이오드) 디바이스의 고휘도, 저전력, 긴 수명, 다양한 색연출 가능, 친환경 소자 등의 장점으로 LED 디바이스가 flat panel display(FPD)의 back light unit (BLU) 를 비롯해 실내 외 조명과 자동차 전조등 분야 이외에도 의료, 인테리어 사업을 비롯한 각종 전자 통신 기기의 정보 처리 기기의 표시소자 등, 여러 제품 군에 적용되는 가운데 큰 관심을 받고 있다. 하지만 이러한 여러 가지 장점에도 불구하고 LED 모듈에서의 junction temperature가 높은 방열 특성이 나쁘다는 단점은 아직 해결되지 않고 있는 실정이다. LED 소자 모듈에서의 junction temperature가 높을 경우 소비되는 에너지가 많을 뿐만 아니라 LED 소자의 발광효율이 떨어지고 수명이 급격히 저하 되어, 결국에는 신뢰성 특성이 현저히 저하 되는 결과가 초래되기 때문이다. 따라서 본 논문에서는 LED 디바이스의 열저항을 낮추기 위해 고방열 세라믹 기판을 이용해 LED 디바이스의 방열 특성을 향상시킨 결과를 제시한다. 고방열 세라믹 기판을 제작하여 LED 칩을 실장시킨 다음 LED 열저항 특성을 측정하였다. 이때 고방열 세라믹 기판은 Al2O3와 AlN이 사용되었으며 제작한 세라믹 기판의 강도, 표면 roughness, 미세구조 등을 살펴보고 이 기판들의 열전도도를 측정하였다. 제작 공정방법에 따라 세라믹 기판의 미세구조를 비롯한 기계적, 열적 특성이 현저히 변하였으며 이때 LED 칩을 실장 하여 측정한 열저항 특성 값도 함께 변하였다. Al2O3의 열저항 값은 3.003 K/W 으로 측정 되었으며, AlN의 열저항 값은 3.003k/W 으로 측정되었다.