• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.1 no.2
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• pp.30-41
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• 1983

This study aims at carrying out the precision leveling by getting the coeicffients of refraction (K) through experiment presented necessarily in the zenith distance measurements of trigonometrical leveling. Thus, the process and characteristics of seasonal and hourly variation of the coefficients of refraction (K) in the Honan district are presented in this paper, especially in the mountainous area surrounded with the Mt. Mudeung, in the coastal area of Mokpo and Yeosu district, and in the plain area of Gwangju district.

• Journal of the Korean Society for Railway
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• v.17 no.5
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• pp.336-341
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• 2014

The articulated structures seen in train or tram applications are being applied in road transportation systems, for use in mass passenger transit. When articulated vehicles are driven on public roads, they no longer follow a guided track. Therefore, there are a lot of control elements that need to be considered, such as turning radius, swept path width, off-tracking, and swing-out. Some of the currently available articulated vehicles on roads are equipped with an independent drive system; a system that has one motor at each wheel. Through this drive system, each wheel can be independently controlled, making precise and quick dynamic stability control possible. In this paper, we propose a torque distribution algorithm that can reduce the overall turning radius of the articulated vehicle, which has been verified through dynamic simulation.

• Journal of Korean Ophthalmic Optics Society
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• v.16 no.3
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• pp.293-297
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• 2011

Purpose: This study was to know the correlation among refractive error and the dimensions of ocular components on older adults. Methods: The subjects were 95 older age who had no eye diseases. The refractive error, corneal radius, corneal diopter, axial length, anterior chamber depth and lens thickness were measured and analysed. Results: The axial length(AL)/corneal radius(CR) ratio was positively correlated with the corneal diopter, axial length, the anterior chamber depth. Then it was negatively correlated with corneal radius. It was shown that the highest correlation was between the corneal diopter and axial length (r = -0.545, p = 0.000). The spherical equivalent of the refractive error was negatively correlated with the AL/CR ratio. Conclusions: It was shown that the AL/CR ratio was a very important indicator for diagnosing the refractive error of the old age.

• Proceedings of the Optical Society of Korea Conference
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• 2000.08a
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• pp.174-175
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• 2000

1946년 S M MacNeille에 의해 연구된 유전체 다층 박막을 이용한 편광광속분리기는 브르스터 각 편광광속분리기(Brewster angle polarizing beam splitter) 혹은 맥닐 프리즘(MacNeille prism)으로 알려져 있으며 지금도 많은 광학계에서 사용되고 있다. 맥닐 프리즘은 두 개의 프리즘 사이의 빗면에 높은 굴절률( $n_{H}$ )을 갖는 물질과 낮은 굴절률( $n_{L}$ )을 갖는 물질을 λ/4 광학두께로 교번으로 한 고반사 다층박막 구조를 갖는다. 각 층의 경계면에서 브르스터 각으로 입사할 경우 p-편광파는 투과하고 s-편광파는 부분적으로 반사한다. 편광광속분리 정도는 p-편광파와 s-편광파의 투과율( $T_{p}$, $T_{s}$ ) 혹은 반사율( $R_{p}$, $R_{s}$ )의 비로 나타내며 이를 소광비(extinction ratio)라 한다. (중략)(중략)략)

• The Optical Journal
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• s.154
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• pp.33-45
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• 2014

■ 광통신용 렌즈는 광통신 시스템에 있어서 송신단과 수신단에 사용되는 하나의 부품으로 집광/발산의 결상 기능을 지니며, 광회로 부품과 광섬유 또는 수발광소자인 LD/PD와 광섬유를 효율 좋게 저손실로 접속하는 기능을 수행함. ■ 마이크로 렌즈는 마이크로 광학의 분야에 있어 광의 집광 및 평행 광으로의 변환에 빠질 수 없는 가장 기본적인 소자로서, 마이크로 렌즈의 종류로는 마이크로 볼 렌즈, 비구면 렌즈와 GRIN 렌즈가 대표적으로 있음. ■ 렌즈에 적용되는 사양으로서 렌즈의 유효 구경, 초점(focal point), 주점(principle point), 주점에서 초점까지의 거리인 초점 거리(focal length), 가상의 법선을 기준으로 빛이 입사되는 각도인 입사각, 빛이 다른 매질을 만나 반사되는 각도인 반사각, 서로 다른 매질을 빛이 통과할 때 굴절하는 굴절각 등이 있음. ■ 렌즈 모듈의 구조는 렌즈, 스페이서(spacer), 아리리스(Iris), 백링(back-ring), 바렐(Barrel)로 구성함. ■ LD 모듈에서 광원에 패브리 페로(FP)로 사용하는 것에는 볼 렌즈가, DFB 광원으로 사용하는 것으로는 비구면 렌즈가 사용하고 있음. 이를 위해 PON용에서는 G-PON의 OLT, ONU 측, GE-PON의 OLT측에는 비구면 렌즈가 사용되나 GE-PON의 ONU측에는 볼 렌즈가 주로 사용되고 있음. ■ 2012년 볼 렌즈 시장은 수량 기반으로 2011년 대비 9.7% 증가한 7,350만 개, 금액기반으로는 17.0% 증가한 3,125만$를 기록하였음. ■ 2012년 비구면 렌즈 시장은 수량 기반으로 2011년 대비 22.0% 증가한 2,220만 개, 금액 기반으로는 32.0% 증가한 8,900만$를 기록하였음. ■ 2012년 광통신용 렌즈 시장(볼 + 비구면)은 수량 기반으로 2011년 대비 12.3% 증가한 9,570만 개, 금액 기반으로는 27.7% 증가한 1억 2,063만$이었음.

• Korean Journal of Optics and Photonics
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• v.7 no.1
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• pp.37-43
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• 1996

Two type interference air refractometers have been developed by using a frequency stabilized He-Ne laser in a transverse magnetic field. The refractometers were based on symmetric multiple pass interferometer. In this system, One part of the beams passed through air whose refractivity is to be measured and the other part of the beams passed through a vacuum champer to be used as a reference. Several measurements were performed under normal air condition. Maximum difference between two interference refractometers was ${\pm}2{\times}10^{-8}$.

• Korean Journal of Weed Science
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• v.7 no.1
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• pp.84-89
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• 1987

This study was conducted to determine the combining effects of a synthetic brassinolide such as homobrassinolide (HBR) with auxin types on the curvature of radish petiole. HBR has no direct effect on the petiole curvature of radish, regardless of concentrations used. Among the natural known plant growth regulators, NAA at 100ppm showed the highest ourvature at 12 hours after treatment. The synthetic auxins such as 2,4-D and MCP resulted in about three times greater effect on curvature than the untreated control, and their effects lasted till 36 horns after treatment, showing much better effect on curvature than that of the natural auxin types of plant growth regulators. The mixture of MCP at 3 ppm with HBR at 100ppm increased petiole curvature of radish seedlings as much as three times greater than that of a single application of HBR. However, the mixture of HBR at 100 ppm plus 2, 4-D at 100ppm increased the petiole curvature of radish seedlings about eight times greater than that of the HBR single application, showing existance of strong synergistic reaction and the most effective combination, and suggesting possibility of a prectical implementation in agriculture.

• Journal of the Korean earth science society
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• v.31 no.6
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• pp.584-599
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• 2010

The variation of atmospheric conditions including subrefraction, normal refraction, superrefraction, and ducting is an important factor that affects the quality of radar data by controling the propagation of radar beams. The occurrence frequency of the conditions is statistically analyzed using the atmospheric soundings from seven radiosonde stations in South Korea over two years. The occurrence of superrefraction and ducting at Baengnyeongdo is significantly higher than the others. Osan and Kwangju show significant variation in time. Among the different duct conditions, the surface duct is dominant at most stations except for Gosan. The elevated duct is dominant at Heuksando and Gosan. Duct is more frequent in summer than in winter at all stations. Baengnyeongdo shows the most frequent duct in spring, fall, and winter while Pohang had the highest frequency in summer. Osan and Kwangju show least duct during all seasons. The difference of variation of monthly duct occurrence between 00 UTC and 12 UTC is insignificant at all stations except for Osan and Kwangju. Kwangju, Heuksando and Gosan show relatively low frequency of duct with the monthly maximum barely reaching 60%. The highest number of elevation angles that are affected by duct was four at Osungsan radar (KSN). The maximum elevation angle is around $1.0^{\circ}$ at all stations and Jindo radar (JNI) shows the maximum value of $1.2^{\circ}$.

• Journal of Korean Ophthalmic Optics Society
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• v.20 no.4
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• pp.485-489
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• 2015

Purpose: The kappa angles of human eye were measured by photographs. The relationship between the dominant eye and far refractivity is studied. Methods: 112 adults participated in this study. The mean age was $22.54{\pm}5.90$ years. The kappa angles were measured by the deviation of the flash image in the photographs of eye. the dominant eye and the far refractivity were analyzed. Results: The distributions of kappa angles were 78.6% (176 eyes) in the positive angle, 15.2% (34 eyes) in the negative angle, and 6.2% (14 eyes) in the $0^{\circ}$. The kappa angles were $4.50{\pm}4.70^{\circ}$ for the dominant eye, $4.93{\pm}4.34^{\circ}$ for the non-dominant eye, $+6.00{\pm}2.22^{\circ}$ for the hypermetropia, $4.91{\pm}4.97^{\circ}$ for the emmetropia, and $+4.61{\pm}4.49^{\circ}$ for the myopia. The biggest kappa angles was odserved in the hypermetropia and the angles was getting smaller in the emmetropia, and the myopia. Conclusions: The kappa angle of the dominant eye was smaller than non-dominant eye. The kappa angle was smaller as the far refractivity is lower. The kappa angle can be directly measured by the photographic method.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.27 no.2
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• pp.188-197
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• 2016

In this paper, we propose a method that represents a mathematical form of wave propagation by using the fact the refractive index determining wave propagation characteristic is a function of altitude. Proposed method uses Snell's law that expresses relationship between incident angle and refraction angle when incident wave passes medium having a different refractive index. We present the simulation results about wave propagation by setting the square of refractive index in the form of the polynomial for altitude and show that it is possible to estimate the coefficients of the polynomial through the angle information from vertical axis of multiple radar systems.