• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2007년도 춘계학술대회 논문집
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• pp.229-230
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• 2007

• 한국방사선학회논문지
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• 제10권7호
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• pp.521-529
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• 2016

감마나이프 방사선수술은 일회에 고방사선량을 조사하는 치료 전략에 기초하기 때문에 렉셀감마플랜의 결과물에 대한 독립적인 검증은 환자의 안전성을 보장하고 치료 오류의 위험을 최소화하는데 중요한 절차 중 하나이다. 기존에 개발된 여러 검증 방법들의 구현을 통해 통계적으로 검토하고 치료에 시도했다. 이 연구의 목적은 감마나이프 치료에 대해 제안된 여러 검증방법의 정확도를 적용하고 평가하는 것이었다. 본 연구에서 감마나이프방사선 수술에 의해 치료된 두개 내 병변을 가진 10명의 환자가 포함되었다. 우리는 최대 선량, 임의의 점에서의 선량, 등선량중심점에서의 치료시간에 관하여 제안된 알고리즘과 렉셀감마플랜으로 획득한 데이터를 비교 하였다. 모든 데이터는 두 개의 상이한 측정 기법을 비교하기 위해 사용되는 통계적 방법인 대응표본 t 검정에 의해 분석되었다. 10가지 사례에서 최대 선량의 통계적 유의성은 제안된 검증방법과 렉셀감마플랜 사이에 관찰되지 않았다. 평균 최대 선량의 차이는 -0.53 Gy에서 3.71 Gy범위내였다. 제안된 검증방법과 렉셀감마플랜에 의해 계산된 임의의 점에서의 선량 또한 통계적으로 유의하지 않았다. 그러나 우리는 등선량중심점에서의 치료시간에 대한 조직최대비율 알고리즘과 렉셀감마플랜사이에 p=0.021인 통계적인 차이가 발견되었다. 통계적 분석에 의하면 제안된 검증방법은 감마나이프 방사선수술의 최상의 치료계획을 위해 최대 선량과 임의의 점에서의 선량을 고려할 때 렉셀감마플랜과 상당히 일치한다고 볼 수 있다. 제안된 검증방법들은 과다선량 조사 가능성을 최소화하기 위한 통상적인 정도관리 절차의 일부분으로 통합될 수 있다고 여겨진다.

• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 2009년도 추계학술대회 논문집
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• pp.73-76
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• 2009

The optical structure of edge-lit LED backlight has been optimized via simulation study in order to remove bright spots appearing on the entrance region of the light guide plate (LGP) and thus to improve the luminance uniformity. The density of scattering dots located on the back surface of LGP was adjusted according to the location of LED's. In addition, lenticular lenses or a diffuse transmissive surface were formed on the side surface of LGP facing the LED's, and the density of lenticular lenses was optimized for redistributing rays emitted from LED's into wider angles. The bright spots which could be seen from conventional LED backlight were removed by the combination of these two optical structures. The application of diffuse surface to the entrance face gave better uniformity than the application of lenticular lenses. However, dark regions still appear on the entrance region of LGP, which should be removed by more appropriate optical design for achieving better luminance uniformity on the LED backlight.

• 한국위성정보통신학회논문지
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• 제9권1호
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• pp.70-73
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• 2014

최근 휴대용 정보전자기기의 비약적인 사용의 증가는 충격에 보다 강한 디스플레이에 대한 연구를 발전시키는 계기가 되었다. 일부 제조회사에서 AMOLED를 사용한 디스플레이에서 유연한 특성을 가진 제품을 선보이고 있으나, 그 사용량에 있어서 압도적으로 많은 부분을 차지하고 있는 것은 LCD 이다. 특히 LCD는 구조적인 문제로 인하여 반드시 후면광원을 사용하여야 하는데, 면발광형식의 조광장치를 얇은 두께로 구현하는데 사용되는 것이 아크릴 재질의 도광판이다. 본 연구에서는 유연하지 않은 메틸메타아크릴레이트에 부틸 아크릴레이트 고무계열의 합성재료를 첨가하여 유연성을 유지하고, 투과율을 90%까지 상승시킨 KURARITY 라는 재질을 사용한 패턴의 설계 및 성형 결과를 통해서 유연한 후면광원의 가능성을 평가하는데 주력하였다. 평가 결과 기존의 광원과 동일한 수준의 밝기 및 휘도 균일도를 얻을 수 있었다.

• 소성∙가공
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• 제16권1호
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• pp.42-47
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• 2007

LCD-BLU is one of kernel parts of LCD and it consists of several optical sheets: LGP, light source and mold frame. The LGP of LCD-BLU is usually manufactured by etching process and forming numerous dots with $50\sim300{\mu}m$ diameter on the surface. But the surface of the etched dots of LGP is very rough due to the characteristics of the etching process during the mold fabrication, so that its light loss is high along with the dispersion of light into the surface. Accordingly, there is a limit in raising the luminance of LCD-BLU. In order to overcome the limit of current etched dot patterned LGP, optical pattern with continuous microlens was designed using optical simulation CAE. Also, a mold with continuous micro-lens was fabricated by UV-LiGA reflow process and applied to 7 inch size of navigator LCD-BLU in the present study.

• Korea-Australia Rheology Journal
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• 제19권3호
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• pp.171-176
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• 2007

LCD-BLU (Liquid Crystal Display-Back Light Unit) of medium size is usually manufactured by forming numerous dots with $50{\sim}300\;{\mu}m$ in diameter by etching process and V-grove shape with $50\;{\mu}m$ in height by mechanical cutting process. However, the surface of the etched dots is very rough due to the characteristics of the etching process and V-cutting needs rather high cost. Instead of existing optical pattern made by etching and mechanical cutting, 3-dimensional continuous micro-lens of $200\;{\mu}m$ in diameter was applied in the present study. The continuous micro-lens pattern fabricated by modified LIGA with thermal reflow process was tested to this new optical design of LGP. The manufacturing process using LIGA-reflow is made up of three stages as follows: (i) the stage of lithography, (ii) the stage of thermal reflow process and (iii) the stage of electroplating. The continuous micro-lens patterned LGP was fabricated with injection molding and its test results showed the possibility of commercial use in the future.

• 소성∙가공
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• 제17권8호
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• pp.657-661
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• 2008

Recently, products of electronic industry and related parts are required to have the thickness thinner and thinner to reduce the part weight. To go with this trend, LGP(light guide plate) of LCD-BLU(Liquid Crystal Display-Back Light Unit: It is one of kernel parts of LCD) for cell phone has the thickness of ${\sim}0.3mm$ and the battery case of cell phone has ${\sim}0.25mm$. Accordingly, high speed injection molding is required to mold products which have thinner parts. To achieve high speed injection and proper control of hydraulic unit, various design was applied to conventional injection unit. In the present paper, we concentrated on the molding stability of hydro-mechanical high speed injection machine to make an LGP of 0.3mm thickness.

• 한국표면공학회지
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• 제47권5호
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• pp.233-238
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• 2014

In this paper, in order to achieve slim and light liquid crystal display, we examine the optical conditions that can obtain uniform light with higher optical efficiency over whole light guide plate (LGP) through simulation. Furthermore, to overcome the issues of hot spot in front of red, green, and blue light emitting diodes (RGB LEDs) source and non-uniform color mixing, we propose four shaped color mixing bars tied up with the LGP and check the optical characteristics of the LGP with them by simulation. Consequently, we could know the optical conditions of improving optical efficiency and optical uniformity in the LGP through the optical design. Also we confirmed that the issues of the hot spot and non-uniform color mixing in edge type LED could be solved by using the ${\bigwedge}$-shaped window color mixing bar.

• Journal of Korean Neurosurgical Society
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• 제53권2호
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• pp.102-107
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• 2013

Objective : The Leksell Gamma Knife$^{(R)}$ (LGK) is based on a single-fraction high dose treatment strategy. Therefore, independent verification of the Leksell GammaPlan$^{(R)}$ (LGP) is important for ensuring patient safety and minimizing the risk of treatment errors. Although several verification techniques have been previously developed and reported, no method has ever been tested statistically on multiple LGK target treatments. The purpose of this study was to perform and to evaluate the accuracy of a verification method (modified variable ellipsoid modeling technique, MVEMT) for multiple target treatments. Methods : A total of 500 locations in 10 consecutive patients with multiple brain tumor targets were included in this study. We compared the data from an LGP planning system and MVEMT in terms of dose at random points, maximal dose points, and target volumes. All data was analyzed by t-test and the Bland-Altman plot, which are statistical methods used to compare two different measurement techniques. Results : No statistical difference in dose at the 500 random points was observed between LGP and MVEMT. Differences in maximal dose ranged from -2.4% to 6.1%. An average distance of 1.6 mm between the maximal dose points was observed when comparing the two methods. Conclusion : Statistical analyses demonstrated that MVEMT was in excellent agreement with LGP when planning for radiosurgery involving multiple target treatments. MVEMT is a useful, independent tool for planning multiple target treatment that provides statistically identical data to that produced by LGP. Findings from the present study indicate that MVEMT can be used as a reference dose verification system for multiple tumors.

• 한국정밀공학회지
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• 제23권9호
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• pp.174-178
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• 2006

Pyramid shape of micro pattern is applied to the light guide panel (LGP) to enhance the uniformity of the brightness of the LCD. The micro pyramids are molded in intaglio on the surface of the LGP. The size of each pyramid is 5$\mu$m $\times$ 5$\mu$m on bottom and the height is about 3.5$\mu$m. The pyramids are distributed on the LGP surface randomly to be sparser where the light comes in and denser at the opposite side as a result of a simulation using lightools$^{TM}$ Based on this design, a silicon pattern master and a nickel stamper are fabricated by MEMS process and electro plating process. Intaglio micro pyramids are fabricated on the 6' of silicon wafer from the anisotropic etching using KOH and the process time, temperature of the KOH solution, etc are optimized to obtain precise shape of the pattern. A Wi stamper is fabricated from this pattern master by electro plating process and the embossed pyramid patterns turns out to be well defined on the stamper. Adopting this stamper to the mold base with two cavities, 1.8' and 3.6' LGPs are injection molded.