• 한국전기전자재료학회논문지
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• 제25권3호
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• pp.209-212
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• 2012

In this paper, we have studied on the optimal design of the optical compensation film for the TN-LCDs. To have wide viewing angle panels, several methods such as multi-domain method, optical path method, and phase compensation method have been proposed. Among these methods, this paper focused on the phase compensation method. In the phase compensation method, the phase retardation generated from the optical birefringence for the off-axis incident is compensated by using optical films with refractive anisotropy. To compensate the phase retardation of the TN-LCDs, we have proposed design concept for the biaxial optical films and analyzed the optical performance for the proposed structures. The calculation of the dynamic motion of the liquid crystals was based on the Ericksen-Leslie theory and the optical performance of the TN-LCD was calculated from the Extended Jones Matrix Method. From the results, we have confirmed that the optical characteristics of the TN-LCDs with the biaxial films have been improved considerably compared with the TN-LCDs compensated by the combination of the uniaxial films.

• Journal of Biosystems Engineering
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• 제41권3호
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• pp.177-183
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• 2016

Purpose: Mee (Madhuca longifolia) is an economically important tree growing throughout Sri Lanka. Its importance is mainly attributed to its oil with high nutritional and medicinal values. However, an inefficient extraction method limits its use. This study revealed the possibility of extracting oil from mee seeds by using a screw-type oil expeller. Methods: A popular screw-type oil expeller was used in the experiment. Extract bar clearance and speeds of the main spiral shaft were altered to increase the oil expelling efficiency of the machine. The quality of refined oil at the optimum oil yield was determined by measuring the refractive index, saponification value, iodine value, unsaponifiable matter, free fatty acid, and specific gravity. Results: An optimum yield of 35% oil was obtained when the machine capacity was 30 kg/h and energy consumption was 0.13 kWh/kg. This optimum machine condition was observed at an extract bar clearance of 0.5 mm and a main spiral shaft speed of 90 rpm. The refractive index, saponification value, iodine value, unsaponifiable matter, free fatty acid, and specific gravity of the oil were 1.4, 203, 59, 3.5%, 0.2%, and 0.907 g/cm3 respectively. Color of the mee oil was closer to yellow, which is revealed by the lightness value (L) of 24.93 and positive value (b) of 11.81. Conclusion: The screw-type oil expeller can be used for economically extracting mee oil on a commercial scale.

• 한국식품영양과학회:학술대회논문집
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• 한국식품영양과학회 2001년도 International Symposium on Food,Nutrition and Health for 21st Century
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• pp.52-60
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• 2001

Purpose: We performed a randomized, double-blind, placebo-controlled trial in mild to moderate myopia patients to evaluate the benefit of taking a nutrient supplement containing anthocyanoside oligomers for improving nocturnal visiual function and/or clinical symptoms. Methods: The subjects included have refractive error between -lD(Diopters) $\~$-8D in both eyes, symptoms of decreased night vision and asthenopia based on the scoring result of a pre-structured questionnaire, and abnormal results of mesopic contrast sensitivity(MCS) screening test showing abnormal curve of contrast sensitivity in the middle and high frequency level, between 6.0 and 30.0 CPD(Cycles per degree) at mesopic condition(-2$\~$0 log cd/$m^2$). Total 60 people who qualified the criteria above were enrolled and the subjects were instructed to take the investigational product (anthocyanoside or placebo) twice daily for a 4 week period. The enrolled subjects were investigated for nocturnal vision performance by MCS and clinical symptoms at their first visit and re-evaluated at post-intervention (4 weeks later). MCS was measured and improvement of contrast threshold level according to each CPD was calculated by subtracting initial values from final values. Age, refractive error, and MCS were compared between the placebo and anthocyanoside. Results: After 4 weeks of drug administration 22 of the anthocyanoside group showed symptom improvement compared to 1 of the placebo group (p=0.000). Contrast sensitivity levels according to each CPD before and after drug treatment showed significant improvement in the anthocyanoside group but not in the placebo group. Mean MCS change of anthocyanoside group is 2.41$\pm$1.91 which showed significant improvement compared to -0.40$\pm$2.47 of the placebo group(p=0.000). MCS changes of anthocyanoside group showed significant improvement compared to placebo group in all levels of CPD(p<0.05). During our investigation none of the subjects complained of specific side effects related to anthocyanoside use. Conclusion: Our results show that under careful selection of people with significant symptoms and definite MCS abnormalities, anthocyanoside oligomers may improve the subjective symptoms and objective MCS results.

• 통합자연과학논문집
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• 제6권1호
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• pp.1-7
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• 2013

Polyurethane resin containing isocyanate is marked by excellent tensile and mechanical strengths and this test aims to gauge its applicability as a medical high polymer. Tris [2-(acryloyloxy)ethyl]isocyanurate and hexamethylenediisocyanate were added to a basic mixing ratio of HEMA (2-hydroxyethyl methacrylate), MMA (methyl methacrylate), NVP (n-vinyl-2-pyrrolidone) and crosslink agent, EGDMA (ethylene glycol dimethacrylate) with increasing proportions and copolymerized respectively. Also, the basic physical properties of the polymerized high polymers including refraction rate, tensile strength, light transmission and water content were measured to confirm that they are appropriate as hydrogelcontact lenses. After measuring the physical properties of high performance polymers produced by adding tris [2-(acryloyloxy) ethyl]isocyanurate, it was found that the average tensile strengths of sample TRIS1 to TRIS10 were between 0.285 and 0.612 kgf, while the average values of refractive index were ranged from 1.441 to 1.449 with water content from 30.00 to 37.35%.The measurement of physical properties of the copolymers generated by adding hexamethylenediisocyanate showed that the average tensile strength of sample HEXA1 to HEXA10 ranged from 0.267 to 1.742 kgf, the refractive index ranged from 1.443 to 1.475 and water contents were in the range of 21.22 to 35.58%. In all combinations the transmission rates satisfied the transmittance of general hydrogel contact lenses. From theresults, it is possible to conclude that the produced copolymers can be used as contact lens materials with excellent tensile strength.

• 대한화학회지
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• 제55권1호
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• pp.98-103
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• 2011

본 연구는 자외선 흡수제로 사용되는 benzophenone계(group) 및 높은 굴절률과 화학적, 물리적으로 매우 안정한 물질로 알려진 $TiO_2$를 기존의 재료에 첨가하여 자외선 차단 기능을 가진 고분자 재료를 중합하였다. 중합 결과 생성된 고분자의 자외선 흡수 정도를 기존의 재료들과 비교하였으며, 제조된 콘택트렌즈의 함수율, 굴절률 및 광투과율등의 기본적인 물성을 측정하였다. 측정 결과, 자외선 흡수제를 첨가한 콘택트렌즈의 굴절률과 함수율은 각각 1.430~1.440, 35.0~45.0의 값들로 나타나 기존의 콘택트렌즈와 비슷한 결과를 나타내었다. 또한 각 파장대별 광투과율에서는 자외선 흡수제를 넣지 않은 콘택트렌즈에서는 UV-A, UV-B, 가시광선 투과율이 각각 89%, 88%, 89%로 나타나 자외선 투과율이 매우 높았으나, 2-hydroxy-4-methoxy-benzophenone와 2,4-dihydroxy-benzophenone을 첨가한 콘택트렌즈의 경우, 각각 UV-A 0%, UV-B 6%의 투과율을 나타내어 자외선 차단 효과가 있는 것으로 나타났다. 또한 $TiO_2$를 첨가한 콘택트렌즈의 경우, 각각 UV-A 6%, UV-B 51%의 투과율을 나타내어 자외선 차단 효과가 다소 있는 것으로 나타났다. 가시광선 투과율은 모두 77~89%로 콘택트렌즈의 가시광선 투과율의 조건에 만족함을 알 수 있었다.

• 한국광학회지
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• 제18권4호
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• pp.256-263
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• 2007

SELFOC 소재를 사용하여 높은 수치구경을 가지는 광픽업용 대물렌즈를 설계하였다. SELFOC 소재는 radial gradient-index 분포를 가지며, 이것은 설계에 추가적인 자유도를 제공하므로, 비구면이 아닌 구면만으로 높은 수치구경의 대물렌즈의 설계가 가능하다. 이 연구에서는 quadratic constant와 광축의 굴절률, 광축 두께, 입사동 직경을 변화시키며 rms 스폿 직경 변화를 조사하였으며, Code V를 사용하여 대물렌즈의 최적화와 결상특성을 평가하였다. 이 분석에서는 quadratic constant와 광축의 굴절률이 클수록, 렌즈가 두꺼워질수록, 입사동 직경은 작을수록 더 좋은 특성을 보임을 알 수 있었다. 이 결과를 바탕으로 2매의 구면 SELFOC 렌즈로 구성된 높은 NA의 DVR용 대물렌즈를 설계하였으며, 2가지 형태의 해 Solution I, II가 존재하였다 Solution I은 두 매 모두 양의 굴절능을 가지며 compact한 광학계를 구성하지만, 비축 수차 보정이 Solution II에 비해 부족하였다. Solution II는 음-양의 굴절능으로 조합된 광학계로 비축 수차가 비교적 잘 보정되었지만, 광학계의 전장길이가 길고 렌즈의 직경이 커지는 문제점이 있었다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2009년도 추계학술대회 논문집
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• pp.160-160
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• 2009

In recent years, the merging of nanomaterials and nano-technology into electro-optic (EO) device technology such as liquid crystal displays (LCDs) has attracted much attention because of their unique electro- and magneto-optic properties and novel display applications. One example of hybrid LC-inorganic systems is semiconductor nanorods added to LC for their strong reorientation effect and tunable refractive index. Doping of nanoparticles in LC or polymers can lead to changes in performance characteristics such as electro-optical, dielectric, memory effect, phase behavior, etc. Due to the tunability of LCDs with mixed inorganic materials, low voltage operation of a LC system can also be achieved using the significant electro-optical effect achieved through suspension of ferroelectric nanoparticles in NLC.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1997년도 한국자동제어학술회의논문집; 한국전력공사 서울연수원; 17-18 Oct. 1997
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• pp.1415-1418
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• 1997

An accurate length measuring system has been develope by a modified Michelson interferometer. A frequency stabilized laser source and a 20 fold frequency interpolation and digitizing circuit were applied to the system. Resolutioin of .lambda./40, 16 nm, was achieved from the discrete length measuring system. In order to obtain a resoltuion of 1.mu.m a decimalizing module was designed for the 0.016.mu.m resolution system. The refractive index of the ambient air was calibrated on the decimalizing module through the Edlen's formula. Performance of the system was evaluated on the machining center in short and long length measruements.

• 제어로봇시스템학회논문지
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• 제7권5호
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• pp.427-431
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• 2001

An on-line refractometer made of easily obtainable materials is built to determine the concentration of an alcohol solution, and its performance is examined by applying to the system of ethanol and water. Since the refractive index and the temperature are measured simultaneously, it is possible to compensate the effect of temperature which is not available with an existing on-line refeactometer. Therefore, it can be implemented in the application of process control. The experimental outcome indicates that the home-made refractometer has satisfactory reproducibility and reasonable accuracy for the industrial application.

• 제어로봇시스템학회논문지
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• 제9권6호
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• pp.473-477
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• 2003

An immersion-type on-line refractometer useful for the in-situ measurement of chemical composition and temperature is developed, and its performance is examined by applying the refractometer to known alcohol solution having concentrations between 0 vol. % and 25 vol. %. Because refractive index and temperature are measured simultaneously, it is possible to compensate the effect of temperature for fast and direct measurement. The outcome of composition measurement for the different concentrations of alcohol solution indicates that the device is suitable for the chemical composition measurement by yielding stable and reproducible reading.