• 천문학회보
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• 제35권2호
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• pp.43.1-43.1
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• 2010

A novel method to characterize the topology of the early-universe intergalactic medium during the epoch of cosmic reionization is presented. The 21-cm radiation background from high redshift is analyzed through calculation of the 2-dimensional (2D) genus. The radiative transfer of hydrogen-ionizing photons and ionization-rate equations are calculated in a suite of numerical simulations under various input parameters. The 2D genus is calculated from the mock 21-cm images of high-redshift universe. We construct the 2D genus curve by varying the threshold differential brightness temperature, and compare this to the 2D genus curve of the underlying density field. We find that (1) the 2D genus curve reflects the evolutionary track of cosmic reionization and (2) the 2D genus curve can discriminate between certain reionization scenarios and thus indirectly probe the properties of radiation-sources. Choosing the right beam shape of a radio antenna is found crucial for this analysis. Square Kilometer Array (SKA) is found to be a suitable apparatus for this analysis in terms of sensitivity, even though some deterioration of the data for this purpose is unavoidable under the planned size of the antenna core.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2003년도 춘계학술대회 논문집 디스플레이 광소자분야
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• pp.169-172
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• 2003

기존의 Monitor 대응 LCD 에서 TV 대응 LCD로의 개발에 있어서 특성 개선은 다각도로 진행되고 있으나, 무엇보다도 휘도 특성의 개선이 요구된다. TV 대응 LCD Panel 은 Monitor 대응 제품에 비해서 일반적으로 해상도가 낮으므로, 투과율면에서 장점은 있으나, 현재의 B/L 구조로는 만족할만한 성능을 낼 수 없는 상황이다. 고휘도 BL(Back Lignt)를 위해서 EEFL(External Electrode Fluorescent Lamp) 혹은 CCFL 의 복수 사용을 전제로 한 직하방식에 대한 개발 검토가 활발히 이루어지고 있으나, 직하방식에 의한 고휘도화는 램프수의 증가에 따른 인버터의 기구적, 전기적 사양의 증가를 필요로 하며, LCD Module전체의 두께가 증가되는 문제를 가지고 있다. 본 연구에서는 L-Shaped 램프를 적용하여 기본의 기구적인 사양 및 전기적인 사양을 유사하게 유지함과 동시에, 고휘도화를 실현하여 TV 대응 수준을 확보하였으며, lamp를 floating구동하여 램프편측 전압 500V를 사용하면서 655 nit의 휘도를 달성하였다.

• 한국인터넷방송통신학회논문지
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• 제20권4호
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• pp.149-154
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• 2020

본 연구에서는 블루투스를 이용하여 스마트폰 으로 제어되는 Smart Diffuser 디바이스의 초기모델을 개발하였다. Smart Diffuser는 디바이스에 주입하는 오일을 분사시키기 위해 초음파 진동자를 이용하였다. 고휘도 LED를 사용하여 오일이 분사되는 동안에 색상 변화가 보여 지도록 디바이스를 개발하였다. 휴대용 디바이스인 점을 감안하여 충전 시간 문제를 해결하기 위해 40mAh의 Li-Po 배터리를 사용하여 장시간 사용할 수 있도록 설계를 하였다. Bluetooth Low Energy를 이용하여 저전력 구동을 구현을 함으로서 초기 설계모델의 유용성에 대해 확인 하였다.

• 전자공학회논문지
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• 제51권7호
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• pp.89-95
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• 2014

주위 밝기 및 환경에 따라서 LED 조명등의 밝기를 조절하기 위한 장치를 PWM 기술과 전력 소자를 이용하여 구현하였다. 주위의 광량 측정을 위하여 CdS 센서를 사용하였으며, PWM 신호 생성을 위하여 MCU를 사용하여 제어 보드를 설계한 다음 광량에 따라 듀티비를 조절하였다. 고전압, 대전류를 필요로 하는 LED 조명등을 디밍하기 위하여 전력 소자를 사용하여 DC 전원장치의 출력을 스위칭하였으며, PowerMOSFET, IGBT, PowerBJT를 각각 사용하여 특성을 서로 비교하였다. 실험결과 선형성 면에서는 IGBT가 양호하였으나, 효율 및 가격 면까지 고려하면 PowerBJT도 우수한 특성을 보였다.

• 천문학회보
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• 제37권2호
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• pp.106.1-106.1
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• 2012

The Gegenschein is a faint glow around the anti-solar point caused by the interplanetary dust particle(IDP)'s back-scattering enhancement. From the previous low resolution observations, the overall morphology of the Gegenschein has been intensively studied. However, sub-degree scale fine structure of the Gegenschein is still not well known, even though the detailed morphology of the Gegenschein within a few degree from the anti-solar point may supply pivotal information about the property of the IDPs. We made optical CCD observations of the Gegenschein between 2003 March and 2006 November. From the observations, we succeeded in making high resolution images of the Gegenschein, with unprecedented 1.'4 resolution. Our results concur with IDP cloud model based on the infrared observations combined with scattering phase function derived from low resolution data. The only exception is the anti-solar point. We found a steep additional brightness enhancement existing at the exact anti-solar point. Plausible explanation of the finding is that the IDPs are significantly larger than observing wavelength, and have irregular morphology or inhomogeneous internal structure. Furthermore, we measured average geometric albedo of the IDPs from the optical brightness of the anti-solar point. The geometric albedo was $0.06{\pm}0.01$, similar to those of comets or C-type asteroids.

• 한방안이비인후피부과학회지
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• 제29권2호
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• pp.106-111
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• 2016

Objective : The aim of this study is to report the effect of Hani-maehwa laser(fractional mode) treatment on acne scar. Methods : The patient with atrophic facial acne scars was treated with 5 sessions of laser therapy at 4-week intervals. The therapeutic response to treatment was assessed at 3 months after last laser session. The treatment effect was evaluated by standardized photography, anti aging, skin brightness and flatness. That was measured by micro fluorescence measurement camera(ECO SKIN, Cuvitz Inc.) in 16(left zygoma) and 26(right zygoma) spot. And side effects were also checked. Results : Atrophic facial acne scars have improved markedly. Anti aging, skin brightness and flatness were improved. Especially anti aging and flatness were noticeably improved. Adverse effects were not reported.Conclusions : Korean medicine cautery method applies to high level laser(CO₂ Hani-maehwa laser). These are different designs but same principle. It can be considered that laser therapy is effective method for treating acne scars.

• 펄프종이기술
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• 제41권3호
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• pp.42-48
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• 2009

The various kinds of Hanji were manufactured by a few craftsmen at several provinces in Korea. It is very difficult to distinguish each others by its name so-called, Hanji, traditional Hanji, improved Hanji, mechanical Hanji and so on because the manufacturing process, raw materials and characteristics of Hanji are very different from each others. In this research, the functional properties of Hanji depending on the manufacturing process were evaluated and compared each others. The properties of Hanji was greatly changed according to grammage, lye and dochim. The higher the grammage resulted in the lower the pore size and the air permeability. Hanji made by NaOH and CaO showed relatively high brightness than that made by traditional lye(Yuokgae). Hanji treated with dochim can absorb high frequency(2,000 Hz) sound more effectively.

• 반도체디스플레이기술학회지
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• 제22권4호
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• pp.108-112
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• 2023

Precision manufacturing technology is rapidly developing due to the extreme miniaturization of semiconductor processes to comply with Moore's Law. Accurate and precise alignment, which is one of the key elements of the semiconductor pre-process and post-process, is very important in the semiconductor process. The center detection of wafer align marks plays a key role in improving yield by reducing defects and research on accurate detection methods for this is necessary. Methods for accurate alignment using traditional image sensors can cause problems due to changes in image brightness and noise. To solve this problem, engineers must go directly into the line and perform maintenance work. This paper emphasizes that the development of AI technology can provide innovative solutions in the semiconductor process as high-resolution image and image processing technology also develops. This study proposes a new wafer center detection method through variable thresholding. And this study introduces a method for detecting the center that is less sensitive to the brightness of LEDs by utilizing a high-performance object detection model such as YOLOv8 without relying on existing algorithms. Through this, we aim to enable precise wafer focus detection using artificial intelligence.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 하계학술대회 논문집 E
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• pp.2426-2427
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• 1999

This study is the result of determination and analysis to draw out six schools in order to research into the lighting properties of the school Almost schools are supported and used large area by a high brightness lamp, for example high pressure mercury discharge lamp etc. The gymnasium of A, B, E schools have a good capacity of the illuminance.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2008년도 International Meeting on Information Display
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• pp.1001-1004
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• 2008

An advanced backplane circuit technology for AMOLED using amorphous silicon TFTs with commercial level reliability, uniformity and lifetime was recently integrated into a prototype device. Differential aging of T98>100 hrs at 200 cd/m2 brightness and >10,000hrs lifetime is demonstrated. A 2.2" QVGA ($240{\times}320$) prototype has been developed and shown having the above-mentioned high performance.