• Korean journal of applied entomology
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• v.34 no.4
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• pp.334-343
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• 1995

The eyes of Nilaparvata lugens were examined for ultrastructural changes in the light and dark adapted states. Inspection of light microscope sections taken at similar levels of compound eyes from insects kept in light or darkness for periods up to 72 hors revealed some differences between light and dark adapted eyes. Using the electronmicroscope, in light adapted eyes the palisade layer was narrower than that in dark adapted eyes. The pigment granules still formed a ring around the palisade layer in the dark adapted eye but, they did not form a tight circle around the rhabdom. No constant difference was found between the diameters of the microvilli in light and dark adapted eyes. The pigment movements at the junction of the cone and the rhabdom took the effect on varying the pigment aperture at the tip of the cone in front of the rhabdom tip.

• Proceedings of the KSME Conference
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• 2007.05a
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• pp.403-404
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• 2007

Compound eyes in nature present intriguing topics in physiological optics due to their unique optical scheme for imaging. For example, a bee's eye has thousands of integrated photonic units called ommatidia spherically arranged along a curvilinear surface so that each unit points in a different direction. The omni-directionally arranged ommatidium collects incident light with a narrow range of angular acceptance and independently contributes to the capability of wide field-of-view (FOV) detection. Artificial implementation of compound eyes has attracted a great deal of research interest because the wide FOV exhibits a huge potential for medical, industrial, and military applications. So far, imaging with a FOV over $90^{\circ}$ has been achieved only with fisheye lenses which rely on bulky and expensive multiple lenses and require stringent alignment. In this talk, we will discuss about the spherical 3D arrangement of the photonic structures of biologically inspired artificial compound eyes in a small form-factor to have and the functional and anatomical similiarity with natural compound eyes.

• Journal of Korea Foundry Society
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• v.8 no.4
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• pp.422-428
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• 1988

In this study we have investigated the effects of Mm, MmH and $MmH_2$ on the matrix development in cast iron, The conclusive summary is as follows: The spheroidal graphite was observed when 0.5wt.% or more of mischmetal was added and the matrix was of ledeburite structure, but bull's eye structure was not observed. On the other hand, the bull's eye structure was observed when 0.25wt.% of MmH, or 0.25wt.% to 0.5wt.% of $MmH_2$ was added. Above limit of the additives, the matrix changed into ledeburite structure. As the hydrogen content of mischmetal compound increased from MmH, the range of additives to obtain bull's eye structure expanded. This reveals the significant effect of mischmetal hydride on matrix development in cast iron and the possibility of practical use of the additives.

• Korean Journal of Optics and Photonics
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• v.24 no.1
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• pp.9-16
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• 2013

We try to find the generalized structural equation that gives a perspective understanding for telecentric lenses through paraxial optical algebraic equations and preconditions from a highly experienced design sense. The equation is named the $f{\theta}$ formula and this formula is applied to single lenses, double Gauss lenses, Cooke triplet lenses and the compound lens composed of a Cooke triplet lens and a double Gauss lens step by step. And this formula is also applied to single fly-eye lenses plus a telecentric lens and double fly-eye lenses plus a telecentric lens in sequence. As a result, we can confirm that this $f{\theta}$ formula leads to intuitive optical design with a structural understanding for telecentric lens systems.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.08a
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• pp.412-412
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• 2012

갈륨비소(GaAs)는 수직공진표면방출레이저, 발광다이오드, 태양전지 등과 같은 광전소자에 널리 사용되는 물질이다. 그러나 높은 굴절률을 갖는 갈륨비소는 표면에서 30% 이상의 반사율을 갖기 때문에 광손실로 인해 소자의 성능이 저하된다. 따라서 표면 Fresnel 반사율을 낮출 수 있는 효율적인 반사방지막이 필요하다. 최근, 열적 불일치, 물질 선택, 접착력 저하의 단점을 가지고 있는 기존 다중박막을 대체하는 생체모방 서브파장 나노구조가 활발히 연구되고 있다. 이러한 구조는 공기(air)부터 갈륨비소까지 선형적인 유효굴절률 분포를 갖는 유효 단일박막과도 같기 때문에 소자 표면에서의 광손실을 줄일 수 있다. 더욱이, 자연계의 나방의 각막과 나비의 눈의 구조 형태를 모방한 반도체 생체모방 복합 눈(compound eye)은, 즉 마이크로 렌즈모양과 서브파장 나노격자구조의 복합적 형태, 표면에서 우수한 반사방지 특성을 나타낸다. 본 연구에서는, 포토리소그래피와 유도결합플라즈마 식각법을 이용하여 GaAs 기판 표면에 마이크로 렌즈 모양의 패턴을 형성한 후, 스핀코팅을 이용하여 나노 크기를 갖는 실리카 구를 도포하여 건식 식각함으로써 복합 눈 구조를 갖는 갈륨비소 반사방지막을 제작하였다. 제작된 샘플의 표면 및 식각 형상은 전자현미경(scanning electron microscope)을 사용하여 관찰하였으며, UV-vis-NIR spectrophotometer를 사용하여 반사율을 측정하였다.

• Applied Microscopy
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• v.15 no.2
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• pp.89-97
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• 1985

The ultrastructure of the trachea of the compound eye in adult cabbage butterfly, Pieris rapae L., was studied. Trachea under the basement membrane is divided into tracheoles of the ommatidia which blanched 4 tracheoles during 2 divisions. Tracheoles of the ommatidia originated from one tracheolar cell and its nuclear is located under the basement membrane and its cytoplasm enveloped the retinular cell and the retinular pigment cell. The modified structure of tracheoles is located at the first division area of the ommatidia and its size is $8{\mu}mX4.5{\mu}m$. And the length of its taenidium is $0.1{\sim}0.6{\mu}m$, diameter $0.15{\mu}m$, and interval $0.3{\mu}m$.

• Journal of the Korea Institute of Military Science and Technology
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• v.9 no.4
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• pp.90-96
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• 2006

Computer simulation was carried out to develop the tracer composition of a high performance to be able to be observed by not only the naked eye but also the thermal imaging system attached to the weapon system. The results of computer simulation show that the optimum Mg content among the trace compositions is about 40% and the formulation consisted of Viton A has a higher flame temperature compared with that of chloride compound. But the only use of Viton A radiates a yellow light and the composition adding a chloride compound radiates the red light. The light intensity of the tracer composition involving Viton A is higher than that of chloride compound. The tracer composition involving Viton A shows more clear images in case of all tests.

• Journal of Korean Ophthalmic Optics Society
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• v.5 no.2
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• pp.73-78
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• 2000

The purpose of our study was investigation for the status of eye health in Taejon area. I chose the age of eight to under eighteen 61 institutional care children, and I examed the first visual acuity examination ophthalmoscopy and non-criterion interview. Among 61 institutional care children (primary school student 40.98%, secondary school student 59.01%), 56.74% children were emmetropia, 44.46% were ametropia. Unaided visual acuity 0.7, 0.8 were 37.03% of these children. As refractive errors, 31.14% were myopia. 26.23% were compound myopic astigmatism and only 1.64% institutional care children wearing the glasses. In children, early eye examination is essential for their eye health. Therefore attention to early eye examination and wearing correct glasses seem to be very important especially for institutional care children. I propose that we have to concerned about eye health and concrete plan for institutional care children.

• Korean Journal of Optics and Photonics
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• v.34 no.1
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• pp.13-21
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• 2023

We have investigated the acceptance angle and imaging performance of a curved artificial compound eye (ACE), depending on the sag height of the microlens array to maximize its sensitivity to light. When the h/r values increased from 0.22 to 0.37, the acceptance angle of the curved ACE was expanded from 28.70° to 49.02°, which is an enhancement by 70.8%. With the designed optical system, it was demonstrated that a microlens located at the 23rd position from the center of the main lens could still focus an incident beam tilted at 56.35°, so that the letter F was clearly observed.

• Journal of Korean Ophthalmic Optics Society
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• v.5 no.1
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• pp.125-129
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• 2000

To fine understand the visual acuity of female old age. This study was researched the visual acuity test by the object and subject methods. The major findings was as follows: 1. The eye types were 80.94% positive for hyperopia. 13.86% for myopia and 5.19% for emmetropia respectively. 2. The anbormal refraction eye was positive for mixed astigmatism for 78.27%, myoptic com pound astigmatism (10.99%), simple presbyopia(4.97%), myopic simple astigmatism(2.88%), presbyopia compound astigmatism (1.57%), simple myopia(0.78%) and presbyopia simple astigmatism(0.52%). 3. The axis of astigmatism was 60.23% for against regular astigmatism. 22.73% for oblique astigmatism and 17.05% for regular astigmatism respectively. 4. On the total myopic spheric power, the -0.50 spheric equivalent ${\leq}-2.00$ was 90.2%, the -2.00${\leq}-6.00$ was 9.8%. 5. On the total presbyopic spheric power, the -0.50${\leq}-2.00$ was 80.252%, the -2.00${\leq}-6.00$ was 16.99% and 2.56% for anything over the 6.00 diopter. 6. On the astigmatic power, the $0.50{\geq}$ cylinder power${\geq}1.00$ was 69.35%,the 1.00> cylinder power ${\geq}2.00$ was 27.38%, and anything over the 2.00 cylinder diopter was 3.27%.