• Journal of Korean Ophthalmic Optics Society
• /
• v.17 no.1
• /
• pp.67-74
• /
• 2012

Purpose: The purpose of this study to evaluate visual acuity and refractive state and measure and analyze the components of eye's optical system in children and teenagers. Methods: With subjects of 124 (230 eyes) children and teenagers who had no eye diseases, correlation between the correlation between refractive errors and component's of eye's optical system was investigated. The spherical equivalent power of cycloplegic clinical refraction or manifest clinical refraction(SE), corneal power(CP), corneal radius(CR), axial length(AL), anterior chamber depth(ACD) and axial length to corneal radius (AL/CR) ratio were measured and analysed. Results: the SE was negatively correlated with the AL(r = -0.80, p = 0.00), the ACD(r = -0.35, p = 0.00) and the CR(r = -0.11, p=0.00) and positively correlated with the CP(r = +0.11, p=0.00). The AL was positively correlated with the AL/CR ratio (r = +0.84, p = 0.00), the ACD(r = +0.47, p=0.00) and the CR(r = +0.38, p = 0.00) and negatively correlated with the CP(r = -0.38, p=0.00). The CR was negatively correlated with CP(r = -1.00, p = 0.00), the AL/CR ratio(r = -0.19, p = 0.00) and the ACD(r = -0.06, p = 0.39). The CP was positively correlated with the AL/CR ratio(r = +0.19, p = 0.00) and the ACD(r = +0.06, p = 0.39). The ACD was positively correlated with the AL/CR ratio(r = 0.53, p = 0.00). Conclusions: the highest change of refractive errors was shown that the AL/CR ratio was a very important indicator for diagnosing the refractive errors of the children and teenagers.

• The Bulletin of The Korean Astronomical Society
• /
• v.42 no.2
• /
• pp.37.3-38
• /
• 2017

우리나라의 천문 관측의 기록의 역사는 삼국시대 이전 선사시대까지 거슬러 올라간다. 선사시대에는 천문 현상을 바위나 건축 유물에 기록을 남기고 역사를 기록하기 시작한 이후에는 일반 역사 기록 속에 항상 함께 기록하고 있다. 특히 동양은 역사기록 자체가 인간이 남긴 자취뿐만 아니라 하늘과 땅에 일어나는 다양한 자연 현상도 함께 동시에 남겼다. 고대로부터 인간은 하늘과 땅과 항상 유기적인 관계를 갖는다고 믿었기 때문이다. 우리나라는 정사로서 가장 오래된 역사 기록인 삼국사기와 삼국유사에 일식, 혜성 출현, 별똥과 유성우, 달과 행성 운행, 초신성 관측 등 250회 이상의 천문 기록이 나타나며 대부분 실제로 일어났던 사실을 그대로 기록하고 있다. 그 후 고려사와 조선왕조실록에는 이루 헤아릴 수 없을 정도로 많은 천문 기록을 남기고 있다. 이러한 천문 기록뿐만 아니라 일찍부터 중국으로부터 역법을 도입하여 천체 운행을 이용하여 우리 생활에 필요한 시각법을 사용하고 달력을 제작하였다. 특히 달과 태양의 운행 원리를 파악하여 일식과 월식을 직접 추산하였다. 역법의 운용은 천체 운행의 원리를 이해하고 수학을 발전시키는데 큰 역할을 하였다. 이러한 천문 관측과 정확한 시각 체계를 유지하고 정밀한 역법을 사용하기 위해서는 끊임없이 천체를 정밀하게 관측할 필요성이 있다. 이를 위해 다양한 천문 관측기기를 개발하고 제작하였다. 천문 의기는 천체의 위치를 측정하고 천체의 운행을 이용하여 시각 체계를 유지 관리를 위해 필수불가결한 기기이다. 우리나라 천문학 발달의 네 가지 축인 천문(天文), 역법(曆法), 의상(儀象), 구루(晷漏)등은 조선 초기 세종시대 완성을 보게 되었다. 이는 단일 왕조가 이룬 업적으로 다른 문화권에서 볼 수 없을 정도의 우수한 과학 기술의 유산이다. 특히 칠정산내편과 외편의 완성은 중국의 역법에서 벗어나 독자적인 역법을 완성하려는 시도였다. 이 모든 것은 당시 이를 주도하던 세종대왕의 지도력과 천문학과 수학에 뛰어난 천문학자가 이룩한 업적이다. 그 후 조선 중기로 접어들면서 쇠퇴하다가 임진왜란과 병자호란을 겪으면서 거의 모든 과학기술의 유산이 파괴되거나 유실되었다. 조선 현종 이후에 세종시대의 유산을 복원하려는 노력 중에 중국을 통하여 서양의 천문학을 도입하게 되었다. 중국에 들어와 있던 서양 선교사들이 주도하여 중국의 역법 체계를 바꾸었다. 즉, 일식과 월식의 예측력이 뛰어난 시헌력을 만들어 사용하기 시작했다. 시헌력에는 서양의 대수학과 기하학을 이용한 다양한 수학적 기법이 사용되었다. 조선 후기에 이 시헌력을 익히기 위한 노력을 하는 과정에서 서양의 수학과 기하학을 접하게 되고 새로운 우주 체계를 도입하게 되었다. 특히 서양의 천문도와 지도 제작에 기하학의 투사법이 사용되어 복잡한 대수학적 계산을 단순화시켜 활용하였다. 조선 후기에 전문 수학자뿐만 아니라 많은 유학자들도 서양의 수학과 기하학에 깊은 관심을 갖고 연구하였다. 고천문학 전체를 조망해 볼 때 핵심은 현대의 천체물리학이 아니라 위치천문학이다. 따라서 고천문학을 연구하는데 필수적인 요소가 지구의 자전과 공전 운동에 의해서 일어나는 현상과 세차운동에 의한 효과를 정확하게 이해하고 있어야 한다. 그중에서도 구면천문학과 천체역학에 대한 원리를 알고 있는 상태에서 접근해야 한다. 고천문학의 중심인 천문(天文), 역법(曆法), 의상(儀象), 구루(晷漏) 등의 내용은 이러한 위치천문학이 그 기본 골격을 이루고 있다. 예를 들어 고려사의 천문 현상을 모아 놓은 천문지(天文志)와 일식과 월식 계산 원리가 들어있는 역지(曆志)를 연구하기 위해서는 위치천문학의 기본 개념 없이는 연구하는데 한계가 있다. 인문학을 전공하는 학자가 고천문을 연구하는데 가장 큰 걸림돌이 되는 점이 위치 천문학의 기본 개념 없이 접근하는 것이다. 심지어 조선시대 유학자들조차 저술한 많은 천문 관련 기록을 보면 상당부분 천체 운행 원리를 모르고 혼란스럽게 기록된 내용이 적지 않다. 우리나라 수학사를 연구할 경우 방정식 해법, 보간법, 삼각법, 일반 기하 원리에 대한 것을 연구하는데 큰 문제가 없다. 그러나 천문 현상이나 천문 의기 제작에 사용되는 수학은 천문 현상에 대한 원리를 모르면 접근하기 어렵게 된다. 수학사를 하더라고 기본적인 위치 천문학의 기본개념을 이해하고 있어야 폭 넓은 수학사 연구에 성과를 거둘 수 있다. 의외로 천문 현상 추산을 위해 사용되는 수학이나 기하학 원리가 수학사 연구에 중요한 요소가 된다. 더구나 한문으로 기록된 천문 내용을 한문 해독이 능숙한 학자라 하더라도 내용을 모르고 번역하면 도무지 무슨 내용인지 알아볼 수 없는 경우가 많다. 그래서 한문으로 된 천문 현상 기록이나 역법 관련 기록의 번역 내용 중에 많은 오역을 발견하게 된다. 문제는 한번 오역을 해 놓으면 몇 십 년이고 그대로 그 내용을 무비판적으로 인용하게 되고 사실로서 인정하는 오류를 범하게 된다. 이 때문에 우리 선조들이 남긴 고천문 관련 기록에 관한 이해는 우리 현대 천문학자의 역할이 대단히 크다.

• Journal of Korean Ophthalmic Optics Society
• /
• v.20 no.1
• /
• pp.61-66
• /
• 2015

Purpose: In this study, dynamic stereoacuity of 20s' adults were measured by using the Howard-Dolman test(H-D TEST, Bernell, U.S.A), and compared of male and female. And the correlation between dynamic stereoacuity and PD(pupillary distance), and between dynamic stereoacuity and anisometropia caused by difference in the spherical refractive power of the left and right eyes were analyzed. Methods: The mean age of $22.68{\pm}0.50$(20~29)years old, 20s' 63 adults (30 male, 33 female) were conducted for this experiments. After the full correction of subject's refractive error, dynamic stereoacuity was measured 5 times for 1 subject at 2.5 m distance using the H-D test. at 2.5 distance. Results: The mean of dynamic stereoacuity was $28.44{\pm}25.03$ sec of arc for total subjects, $28.23{\pm}23.34$ sec of arc for male, and $28.63{\pm}26.83$ sec of arc for female. In the dynamic stereoacuity classified by the range of inter-pupil distance (IPD), the dynamic stereoacuity was $33.87{\pm}18.53$ sec for the IPD being under 59.80 mm, $26.24{\pm}25.26$ sec of arc for 59.81~66.15 mm, $34.60{\pm}25.65$ sec of arc for over 66.15 mm. However, there were no significant differences between 3 groups (P=0.73, r=0.03). In dynamic stereoacuity classified by the refractive error difference between two eyes, dynamic stereoacuity was $26.81{\pm}24.86$ sec of arc for the under 1 D, $41.45{\pm}24.18$ sec of arc for over 1 D, and there was no significant difference between two groups (P=0.15, r=0.15). Conclusions: Dynamic stereacuity by the H-D test in 20s adults showed that there was no significant differences between male and female, and PD and anisometropia did not have a significant impact upon the dynamic stereoacuity.

• Journal of Korean Society of Forest Science
• /
• v.87 no.3
• /
• pp.358-365
• /
• 1998

To offer the basic information for sustainable production of forest resources and conservation of the global environment, change in potential natural vegetation (PNV) associated with climate change due to doubling atmospheric carbon dioxide ($2{\times}CO_2$) was estimated with the global natural vegetation mapping system based an K${\ddot{o}}$ppen scheme. The system interpolates climate data spherically to each grid cell, determines the vegetation types onto the grid cell, and produces potential vegetation map and area on the globe and continents. The climate data consist of the current, ($1{\times}CO_2$) climate prior to AD 1958 observed at some 2,000 stations and the doubling ($2{\times}CO_2$) climate estimated from Meteorological Research Institute of Japan. The vegetation zone under the $2{\times}CO_2$ climate scenario expanded mainly toward the poles due to the rise in temperature. The changed PNV area on the globe amounts to 1/3 (4.91 billion (G) ha) of the total land area (15.04 Gha). Kappa statistic for judging agreement between the patterns of vegetation distribution under $1{\times}CO_2$ climate and $2{\times}CO_2$ climates shows good agreement (0.63) for the globe as a whole. The most stable areas are desert and ice. The potential forest area (PFA) was estimated at 6.82 Gha of the land area in $2{\times}CO_2$ climate scenario. In terms of continental changes in PFA, North America and Asis are increased under the $2{\times}CO_2$ climate. However, the potential forest arms of the other continents are decreased by the climate. Europe has no change in the PFA. Especially, the expansion of desert area in Oceania would be accelerated by the $2{\times}CO_2$ climate.

• Economic and Environmental Geology
• /
• v.12 no.2
• /
• pp.95-104
• /
• 1979

The position of any point on the earth's surface can be. represented in the spherical coordinates by surface spherical harmonics. Since geomagnetic field is a function of position on the earth, it can be also expressed by spherical harmonic analysis as spherical harmonics of trigonometric series of $a_m({\theta})$ cos $m{\phi}$ and $b_m({\theta})$ sin $m{\phi}$. Coefficients of surface spherical harmonics, $a_m({\theta})$ and $b_m({\theta})$, can be drawn from the components of the geomagnetic field, declination and inclination, and vice versa. In this paper, components of geomagnetic field, declination and inclination in the Korean peninsula are obtained by spherical harmonic analysis using the Gauss coefficients calculated from the world-wide magnetic charts of 1960. These components correspond to the values of normal geomagnetic field having no disturbances of subsurface mass, structure, and so on. The vertical and total components offer the zero level for the interpretation of geomagnetic data obtained by magnetic measurement in the Korean peninsula. Using this zero level, magnetic anomaly map is obtained from the data of airborne magnetic. prospecting carried out during 1958 to 1960. The conclusions of this study are as follows; (1) The intensity of horizontal component of normal geomagnetic field in Korean peninsula ranges from $2{\times}10^4$ gammas to $2.45{\times}10^4$ gammas. It decreases about 500 with the increment of $1^{\circ}$ in latitude. Along the same. latitude, it increases 250 gammas with the increment of $1^{\circ}$ in longitude. (2) Intensity of vertical component ranges from $3.85{\times}10^4$ gammas to $5.15{\times}10^4$ gammas. It increases. about 1000 gammas with the increment of $1^{\circ}$ in latitude. Along the same latitude, it decreases. 150~240 gammas with the increment of $1^{\circ}$ in longitude. Decreasing rate is considerably larger in higher latitude than in lower latitude. (3) Total intensity ranges from $4.55{\times}10^4$ gammas to $5.15{\times}10^4$ gammas. It increases 600~700 gammas with the increament of $1^{\circ}$ in latitude. Along the same latitude, it decreases 10~90 gammas. with the increment of $1^{\circ}$ in longitude. Decreasing rate is considerably larger in higher latitude as the case of vertical component. (4) The declination ranges from $-3.8^{\circ}$ to $-11.5^{\circ}$. It increases $0.6^{\circ}$ with the increment of $1^{\circ}$ in latitude. Along the same latutude, it increases $0.6^{\circ}$ with the increment of l O in longitude. Unlike the cases of vertical and total component, the rate of change is considerably larger in lower latitude than in higher latitude. (5) The inclination ranges from $57.8^{\circ}$ to $66.8^{\circ}$. It increases about $1^{\circ}$ with 'the increment of $1^{\circ}$ in latitude Along the same latitude, it dereases $0.4^{\circ}$ with the increment of $1^{\circ}$ in longitude. (6) The Boundaries of 5 anomaly zones classified on the basis of the trend and shape of anomaly curves correspond to the geologic boundaries. (7) The trend of anomaly curves in each anomaly zone is closely related to the geologic structure developed in the corresponding zone. That is, it relates to the fault in the 3rd zone, the intrusion. of granite in the 1st and 5th zones, and mountains in the 2nd and 4th zones.

• Journal of Korean Ophthalmic Optics Society
• /
• v.19 no.4
• /
• pp.551-555
• /
• 2014

Purpose: This study is to investigate if the improvement of visual sensory (VS) by amblyopia treatment affects the ocular functions in refractive errors, accommodative errors and phoria at distance and near. Methods: 10 subjects (17 eyes, mean age of $10.7{\pm}2.9$ years) who treated amblyopia completely, were participated for this study. Refractive errors, accommodative errors, and distance and near phoria were compared between before and after treatments of amblyopia. Refractive errors and accommodative errors at 40 cm were measured using openfield auto-refractor (NVision-5001, Shin Nippon, Japan) and using monocular estimated method (MEM) respectively. Phoria was determined at 3 m for distance and at 40 cm for near using Howell phoria card, cover test or Maddox rod. Results: Mean corrected visual acuity (CVA) significantly increased from $0.46{\pm}0.11$ (decimal notation) for before amblyopia treatment to a level of $1.03{\pm}0.13$ for after amblyopia treatment (p < 0.001). For spherical refractive error, hyperopia significantly decreased from $+2.29{\pm}0.86D$ to a level of $+1.1{\pm}2.38D$ (p < 0.05) but astigmatism did not significantly change; $-1.80{\pm}1.41D$ for before treatment and $-1.65{\pm}1.30D$D for after treatment (p > 0.05). Accommodative error significantly decreased from accommodative lag of $+1.1{\pm}0.75D$ to a level of $+0.5{\pm}0.59D$ (accommodative lag) (p < 0.05). Distance phoria significantly changed from eso $2.9{\pm}6.17PD$ (prism diopters) to a level of eso $0.2{\pm}3.49PD$ (p < 0.05), and near phoria also significantly changed from eso $0.4{\pm}2.32PD$ to level of exo $2{\pm}4.9PD$ (p < 0.05). There was a high correlation (r = 0.88, p < 0.001) between improvement of visual acuity and decrease of accommodative lag. Conclusions: Hyperopic refractive error decreased with improvement of CVA or VS by amblyopia treatment. And the improvement of VS by amblyopia treatment also improved accommodative error, and changed phoria coupled with accommodation.

• The Korean Journal of Quaternary Research
• /
• v.18 no.1 s.22
• /
• pp.21-30
• /
• 2004

The Ilgwang Fault is NNE-striking, elongated 40 Km between Ulsan and Haeundae-ku, Busan in southeastern part of the Korean Peninsula. This paper si mainly concerned about the ages of the fault activities especially in the Quaternary, inferred from classification of geomorphic surfaces and trench excavation for the construction of Singori nuclear power plant. The geomorphic surfaces are classified into Beach and the Alluvial plain, the 10 m a.s.l. Marine terrace(MIS 5a), the 20 m a.s.l. Marine terrace(MIS 5e), the Reworked surface of 45 m a.s.l. Marine terrace(MIS 7 or 9) and the Low relief erosional surface. The Low relief erosional surface is distributed coastal side, the Reworked surface of 45m a.s.l. Marine terrace inland side by the Ilgwang Fault Line as the boundary line. But the former is above 10 m higher in relative height than the latter. The 20 m a.s.l. Marine terrace on the elongation line of the Ilgwang Fault reveals no dislocation. A site was trenched on the straight contact line with $N30^{\circ}E$-striking between the 10 m a.s.l. Marine terrace and the 20 m a.s.l. Marine terrace. Fault line or dislocation was not observable in the trench excavation. Accordingly, the straight contact line is inferred as the ancient shore line of the 10 m a.s.l. Marine terrace. The Ages of the Fault activities are inferred after the formation of the Ichonri formation - before the formation of the 45 m a.s.l. Marine terrace(220 Ka. y. B.P. or 320. Ka. y. B.P.). The Low relief erosional surface was an island above the sea-level during the formation of the 45 m a.s.l. marine terrace in the paleogeography.

• Korean Journal of Optics and Photonics
• /
• v.28 no.3
• /
• pp.108-115
• /
• 2017

We report the assembly procedure and performance evaluation of a visible and near-infrared spectrometer in the wavelength region of 400-900 nm, which is later to be combined with fore-optics (a telescope) to form a f/2.5 imaging spectrometer with a field of view of ${\pm}7.68^{\circ}$. The detector at the final image plane is a $640{\times}480$ charge-coupled device with a $24{\mu}m$ pixel size. The spectrometer is in an Offner relay configuration consisting of two concentric, spherical mirrors, the secondary of which is replaced by a convex grating mirror. A double-pass test method with an interferometer is often applied in the assembly process of precision optics, but was excluded from our study due to a large residual wavefront error (WFE) in optical design of 210 nm ($0.35{\lambda}$ at 600 nm) root-mean-square (RMS). This results in a single-path test method with a Shack-Hartmann sensor. The final assembly was tested to have a RMS WFE increase of less than 90 nm over the entire field of view, a keystone of 0.08 pixels, a smile of 1.13 pixels and a spectral resolution of 4.32 nm. During the procedure, we confirmed the validity of using a Shack-Hartmann wavefront sensor to monitor alignment in the assembly of an Offner-like spectrometer.

• The Korean Journal of Vision Science
• /
• v.20 no.4
• /
• pp.569-577
• /
• 2018

Purpose : The study looked at how effective each group wearing MyoVison lens, MC lens, and Single Vision lensdepending on their parents' myopia condition. Methods : The study observed the changeof spherical equivalent among customers, who visited between January 2010 and December 2016,of an optical shop in Incheon Metropolitan City. And we observed MyoVision 152 eyes, MC Lens 86 eyes and Single Vision lens 270 eyes. This study was conducted using SPSS ver18, which analyzes the changes in average values of MyoVision, MC Lens, and Single Vision for a year.In each group, the differences in the group were compared using the Paired T-test and then one-way ANOVA (post-hoc; Bonferroni) Results : Group-to-group comparisons showed that MyoVision and MC Lens have a shorterinhibition than Single Vision. In particular, MyoVisionand MC Lens showed different relief effects depending on the degree of refraction of parents.When both parents had normal refractive, the change between MyoVision and Single Vision lens was $-0.35{\pm}0.05D$. When the father had a refraction MC lens were $-0.36{\pm}0.14D$ more effective than Single Vision. When only the mother had refraction, the mean value between MyoVision and Single Vision lens was $-0.37{\pm}0.06D$, and the mean between MC lens and Single Vision lens was $-0.38{\pm}0.08D$. And when both parents had refraction problems, the mean value change between MyoVision and Single Vision lens was $-0.28{\pm}0.07D$, and $-0.31{\pm}0.07D$, respectively. Conclusion : MyoVision and MC Lens appeared to have no effect on the functions of mitigating myopia in within group comparisons, but MyoVision and MC Lens showed reducing myopia than Single Vision in between group.

• The Korean Journal of Vision Science
• /
• v.20 no.4
• /
• pp.523-530
• /
• 2018

Purpose : The purpose of this study was to investigate the difference in the dynamic visual acuity between (DVA) the distance and near and the effect of change of accommodative stimulus on the dynamic visual acuity by the addition of the plus lens. Methods : The study involved 40 male and female adults ($22.84{\pm}2.43$ years old) with over 1.0 of visual acuity and without systemic disease or ocular disease. We compared the distance and near DVA and the change of DVA induced by the addition of the plus lens(+0.50D, +1.00D, +1.50D). Results : The distance DVA and near DVA are $78.86{\pm}19.46deg/sec$ and $76.90{\pm}18.05deg/sec$ respectively. The distance DVA was slightly higher(p=0.04). The higher the distance DVA, the higher the positive correlation with the near DVA and distance DVA, and distance DVA was higher in those who had higher the near DVA(r=0.95, p=0.00, Fig. 4). The near DVA according to the change of accommodative stimulus was $75.95{\pm}18.85deg/sec$ in full correction and the near DVA with +0.50D spherical power was $76.95{\pm}16.45$ but there was no statistically significant differences(p>0.05). However, the near DVA with +1.00D spherical power was $79.02{\pm}13.51deg/sec$ and it was slightly higher. Also, the near DVA with +1.50D spherical power was $84.28{\pm}18.96deg/sec$, there and it was statistically significant difference(p<0.05). Conclusion : There is no difference between distance and near DVA, but near DVA is also excellent if distance DVA is good. The DVA increases as added a plus lens for controlled accommodative stimulation changes.