• Journal of the Korean Society of Manufacturing Process Engineers
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• v.6 no.1
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• pp.7-12
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• 2007

The optic industry is a high value-added advanced technology industry combined with the precision machine industry and the digital electronics industry. The aspheric lens, one of optic parts, is a key technology having a significant influence on the performance of optic equipment. So this study relates to designing an aspheric lens to which a ray-tracing method is applied. In the ray-tracing method, a refractive index of material is used, which take an advantage that the location of a light source and incident angle can be fixed, unlike the ray back-tracing scheme.

• Journal of Korean Ophthalmic Optics Society
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• v.3 no.1
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• pp.263-267
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• 1998

Today's diopter of optical lens can reveal the derivation apparently compared with that of refraction measure lens. First, this is applicable when there is a difference in the shape and thickness basically and when the lens is used for a short distance. When measure and use it, an astigmatic difference is occurred by the discordant light passage. This is also applicable to optical lens with prism diopter lens and in some cases, must be corrected relating to the diopter incidently.

• Journal of Integrative Natural Science
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• v.2 no.1
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• pp.45-49
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• 2009

Electrochemical etching of heavily doped p-type silicon wafers (boron doped, <100> orientation, resistivity; $0.8-1.2m{\Omega}/cm$) with different current density resulting two different refractive indices resulted in DBR (Distributed Bragg Reflectors) porous silicon, which exhibited strong in-plane anisotropy of refractive index (birefringence). Dielectric stacks of birefringent porous silicon acting as distributed Bragg reflectors have two distinct reflection bands depending on the polarization of the incident linearly polarized light. This effect is caused by a three-dimensional (in plane and in depth) variation of the refraction index. Optical characteristics of DBR porous silicon were investigated.

• Proceedings of the Optical Society of Korea Conference
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• 2008.02a
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• pp.141-142
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• 2008

In order to develop a simple ray tracing model for simulating the radiation pattern of a LED, the propagation of a ray within the LED capsule was systematically evaluated by considering refraction and reflection from the capsule-air interface, multiple reflection within the capsule, and total internal reflection at the boundary. It was found that concentric ring shapes on the radiation pattern was formed by the rays multiple-reflected from the capsule surface, and that the strength of these rays were decreased rapidly as the number of multiple reflection is increased.

• Journal of the Korean Institute of Telematics and Electronics
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• v.19 no.5
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• pp.5-11
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• 1982

The dielectric slab waveguide is fabricated on the slide glass or oxidized silicon wafer, by spin coating polyurethane, epoxy or photoresist, and the phenomenon of dielectric waveguiding is oboerved. Using the fact that the refractive index of K.P.R. is larger than that of polyurethane, thin film prism with two layered structure is fabricated, and the refraction of light is observed.

• Journal of Korean Clinical Health Science
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• v.4 no.2
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• pp.550-555
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• 2016

Purpose. We compared with the refracting power and aberration according to the measurement change in illumination and the pupils area by using the auto refraction instruments. Methods. In this study it were examined 64 eyes without eye disease, 21.4 (${\pm}2.54$) age, 32 (male 10, female 22) patients. Experiments in general illumination using the auto refraction instruments (HRK-8000A, Huvitz, Korea) was measured in both eyes 3 times and after scotopic for 30 minutes in a dark room blocked the light was measured in the same way. Aberration were measured coma, spherical aberration, high and low order aberrations in a general illumination (3500 lux) and low illumination (5 lux) of the pupil area 3.96 mm and 5.96 mm. Results. In the general illumination for measuring of the pupil area, the refractive power, coma, spherical aberration and low order aberration was no significant difference. In the low illumination, spherical aberration of the pupil area was $0.005({\pm}0.015){\mu}m$ in a 3.96mm, $0.014({\pm}0.020){\mu}m$ in a 5.96 mm and appeared a significant difference(p = 0.003). In general and low illumination on the results of comparing the measured values of the refractive power and aberration at the pupil area 3.96 mm, high order aberrations was $0.205({\pm}0.145){\mu}m$ in general illumination, $0.132({\pm}0.075){\mu}m$ in low illumination and appeared a significant differences(p = 0.001). High order aberrations at the pupil area 5.96 mm was $0.278({\pm}0.244){\mu}m$ in general illumination, $0.150({\pm}0.092){\mu}m$ in low illumination and appeared a significant differences(p = 0.000). Conclusions. When the eye refractive power measured by the automatic refraction does not depend on the illumination conditions and size of the observation pupil area, it was found that aberrations are affected by the illumination and the observation pupil area. It was found that the eye examination chamber illumination to obtain accurate measurement produces better results to decrease than to increase.

• Textile Coloration and Finishing
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• v.3 no.3
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• pp.57-68
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• 1991

Color vision 현상은 대상물질에 의해서 투과(transmission), 굴절(refraction), 반사(reflection)되어 나오는 광(light)이 망막(retina)에 비칠 때 시신경을 자극하여 뇌에 전달됨으로써 일어나는 하나의 감각현상(sensation)이다. 그러므로 그것은 인간의 감각상태, 광의 종류, 대상물질의 환경조건에 따라서, 즉 시각이 이루어진 그 순간에 인간의 눈이 어떻게 작용 하느냐에 달려있는 복잡한 현상 이다. 그래서 지금까지 발표된 20여개의 색채공간 중 그 어느 것도 인간의 감각량을 똑같이 표현할 수 없었던 것은 사실이다. 모든 자연현상이 그렇듯 인간도 개체마다 모두 다르고 대상물질 및 광에 관련된 너무 많은 요소(Factor)가 색지각 현상에 작용하기 때문에 이의 과학적 표현을 위해서는 단순화 및 normalization의 과정을 거치지 않으면 안되었던 것 같다. 지금까지 발표된 20여개의 color space중, perceptibility에 근거를 둔 유일한 color space인, Munsell color space의 해석에 Spline method 같은 수치 해석적 방법을 쓰지 않으면 안되는 그 이유를 제시하려 한다.

• Journal of Korean Ophthalmic Optics Society
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• v.4 no.2
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• pp.129-133
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• 1999

For the myopia eyes of the people which are ametropia, the classified distribution has showed % for the simple myopic, 50% for the compound myopic astigmatism, 15% for the simple myopic astigmatism and 19% for the mixed astigmatism. The myopic ametropia for the both eyes has the distribution of 35% for -0.50D~-2.00Dptr, 54% for -2.00~6.00Dptr, and 11% for over -6.00Dptr. The classifying distribution for the age for the myopic ametropia was 54% for 15~20, 22% for 21~40, 14% for 41~60 and 10% for 61. The occupational distribution for the myopic ametropia has showed 61.5% for the student(Middle, High, College), 13.5% for the office worker, and 15% for the house wives as well as the small business. The hour affecting the refraction most for a day was after P.M. 7 which recorded 45% as the highest value. The reason is that the myopia degree decreases in the morning as the cornea flats and the situation is reversed in the afternoon so that there is a difference of Sph -0.50D and as getting darker the refraction degree of the light coming through the enlarged pupil refraction around the cornea is high. For the seasons the highest myopic degree has been recorded for 68% in the summer due to the shortage of nutrition and the climination inside the body by the exhaustion of sweat. In the blood types A and B are distributed closely as 34% and more active man with O has recorded higher myopic degree than woman. However woman showed higher accommodation power than man regardless the blood types. In the characteristic factors of myopic eye, the character feels fatigue easily has showed the distribution for 42% which is the highest and it could be classified largely by two the.

• Journal of Periodontal and Implant Science
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• v.27 no.3
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• pp.575-584
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• 1997

The quality of periodontal instrument cutting edge is a basic element of effective root planing procedure. Using instruments, the sharp edge is changed into blunt or beveled edge. With the blunt instrument, the periodontal treatment can't be carried into accuracy and effective. The study on the wear of periodontal curet is insufficient, there are few publications about the change of sharpness of cutting egde after using instrument and a certen reports were published on the study of scanning electron microscope(SEM) examination. In this study, to declare the number of strokes for sharpening of instruments, the changes of cutting edge is measured by the clinical methods, tactile sensitivity examination and refraction light-white line test after scaling strokes and root planing strokes. SEM test was added for defined the changes of cutting edges. The 7/8 Gracey curets that have been never used was tested. Maxillary molars which were extracted from the School of Dental Medicine, Dankook University was used. Subjected teeth had attachment loss more than 6 mm in bucca-lingual surface and sufficient calculus of a band type in cervical area. The strokes of curet were executed 3, 5, 7, 9, 11, 13 times on scaling stroke and 10, 15, 20, 25, 30, 35 times on root planing stroke. A resident has periodontal experience over 3 years carried out the clinical examinations those tactile sensitivity examination and refraction light-white line test 5 times. The case there being tactile sensitivity certenly is 2, the case being felt tactile sensitivity is 1, and the case there not being tactile sensitivity is 0. The visual examination was recorded as following. The case that refracted white line is not recognised is 2, the case that uncerten is 1, and the case that acknowledged is 0. The results were obtained as follows. 1. After scaling strokes, the tactile sensitivity was reduced after 11 strokes and disappeared in 13 strokes. 2. In tactile sensitivity after root planing procedures, sensitivity was reduced after 25 strokes and disappeared in 35 strokes. 3. In case of visual examination, the detection of refracted white line was increased after 9 strokes of scaling procedures and the accuracy of wear wasn't showed after root planing procedures. 4. In SEM, metal projection was observed on new periodontal curet cutting edge and it was disappeared after scaling procedures. 5. In SEM, the cutting edge was showed changing linear into an aspect of the surface after 5 strokes of scaling procedures and 10 strokes of root planing procedures and showed beveled edge in 11 strokes of scaling procedures, 25 strokes of root planing procedures. The results of 3-type examination indicated that the sharpening of curet should be performed after 11 strokes of scaling procedures and 25 strokes of root planing procedures.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.36 no.1
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• pp.9-16
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• 2012

Recently, an optics-based concentrator for solar concentration has been a key issue in development of photovoltaic systems. In the present study, a new, simple, easily producible planar concentrator based on a light guide system is proposed. In this device, solar light is concentrated by microprism optical patterns guiding the light, mainly through total reflection and refraction. The main design variables of the concentrator are the geometric concentration ratio ($R_c$) and the ${\Theta}_1$ and ${\Theta}_2$ of the microprism pattern. Ray tracing was simulated using commercial software, SPEOS, and the optical efficiencies of the light guide solar concentrator were predicted in each case. The predicted maximum optical efficiencies are 65.60%, 54.78%, and 46.78%, respectively, for $R_c$ values of 4, 5, and 6. The variation of the optical efficiencies according to ${\Theta}_1$, ${\Theta}_2$, and the incline angle of the incident light were predicted.