• Korean Journal of Optics and Photonics
• /
• 제28권6호
• /
• pp.290-294
• /
• 2017

The Cassegrain telescope consists of a primary concave mirror and a secondary convex mirror. In the case of a secondary mirror, it is more difficult to test wavefront error than for a primary mirror, because it reflects the entire testing beam, as it is convex in shape. In this paper we tested the wavefront error of a complex aspheric convex secondary mirror by using the Simpson-Oland-Meckel Hindle test. To separate the systematic errors, such as fabrication error and alignment error of a meniscus lens, we adopted the QN absolute test (pixel-based absolute test using the quasi-Newton method) as well. Finally, we compared the measured result with that of an ASI (Aspheric Stitching Interferometer) made by the QED company, which resulted in an rms difference of only 2.5 nm, showing a similar shape of astigmatism aberration.

• Korean Journal of Soil Science and Fertilizer
• /
• 제15권3호
• /
• pp.194-198
• /
• 1982

The data from the fertilizer experiments from 1974 to 1981 were compiled and interpretation were made as to the effect of soil fertility on the quality and yield of cured tobacco supplied with conventional rate (10-15-20, 125Kg/10a). With high soil fertility, the yield of tobacco with conventional rate increased in quadratic curve, but the quality decreased. The results indicate that soil which can produce 81Kg/10a of flue-cured tobacco without fertilizer application would be optimum to the 125Kg/10a fertilizer application. On the other hand, Flue-cured tobacco yields of non-fertilizer plot are supposed to be fertility of determining the application rate which can be recommended.

• Korean Journal of Optics and Photonics
• /
• 제19권1호
• /
• pp.31-35
• /
• 2008

A rod-type aspheric lens collimator for the optical telecommunication system which shows high coupling efficiency and experiences small coupling loss for misalignment errors is designed. The working distance, thickness, and diameter of the rod-type aspheric lens are determined to be close to those of the GRIN lens collimator in order to replace the GRIN lens with the rod-type aspheric lens. Since the coupling loss mainly originated from the spherical aberration of the lens, the spherical aberration in the rod-type aspheric lens is reduced drastically, and it turns out that the coupling efficiency of the rod-type aspheric lens collimator is higher than that of the available collimators, such as ball lens, GRIN lens, and C-type lens collimators.

• Journal of the Korea institute for structural maintenance and inspection
• /
• 제23권1호
• /
• pp.154-162
• /
• 2019

Large scale damage has been globally increased due to natural disasters such as earthquake. Although a variety of studies secured seismic performance of buildings, casualties and economic loss have occurred because of poor security of seismic performance in non-structural components. Structure's location on which non-structural components are installed and characteristics of vibration occurring on each position of structures are varied, so a response spectrum is required for each position of structures. In addition, a response spectrum occurring in a structure is different, depending on the form of it and positions on which it is installed. Therefore, selection of a response spectrum is important, so a definite method for calculating the response spectrum which acts on non-structural components is necessary. A method for choosing a response spectrum is suggested in this paper, and a structural analysis was conducted with the suggested method, by selecting a ground response spectrum and a structural system, which may occur in Korea. Moreover, it helps create a response spectrum necessary for a seismic test of non-structural components, by suggesting the method for deduction it, with a simple formula.

• Korean Journal of Optics and Photonics
• /
• 제31권6호
• /
• pp.328-333
• /
• 2020

In this paper, we study the analysis method for the aspherical tolerance of a Korsch telescope using a Q polynomial. It is important to analyze the tolerances for evaluating quality in high-precision fabrication of aspherical reflectors for high-resolution satellites. Thus we express the aspheric surface in terms of a Q polynomial in which each coefficient term is composed independently, and analyze the tolerance of a Korsch telescope. We also analyze the tolerance using Zernike fringe sag, which expresses the shape error of an aspherical mirror. By comparing the two results, we confirm that the Q-polynomial method can be used to analyze an aspherical mirror.

• Journal of The Korean Society of Grassland and Forage Science
• /
• 제5권2호
• /
• pp.136-142
• /
• 1985

For better grassland development in the forest, this field experiment was carried out to investigate the effect of thirteen different fertilizer levels of nitrogen(N), phosphorus ($P_2O_5$) and potassium ($K_2O$) on the botanical composition, growth and dry matter yield of grass-clover mixtures grown under trees with 40-50% of shading level. This experiment was arranged as a randomized block design with replications, and performed on the experimental field in the suburban forest of Suweon in 1984. The results obtained are summarized as follows: 1. Plant height and cover degree of grasses found to be high with 28 and 42kg N fertilizer per 10a, while those were the lowest with zero and N-zero fertilizer levels. The degree of bare land after the fourth cut was also high in the low N level. 2. A significant higher degree of leaf green and chlorophyll content of leaf blade was observed in the plot of 28 and 42 kg N per 10a when compared with low N fertilizer plot. However, leaf decay and plant type of grasses tended to be a little poor as the high N was applied. 3. the regrowth plant length and dry weight of grasses after the first cut increased significantly with 28 and 42 kg N fertilizer. However, those showed slightly increased regrowth in the plot of zero and N-zero fertilizer levels. 4. The dry matter yield of grasses was higher with 28 and 42 kg N than that of low N fertilizer level. Higher yields were obtained in the plot of standard ($N-P_2O_5-K_2O$=28-20-24 kg/10a), 50% increase of $N,P_2O_5K_2O$ and N-50% increase, although there were no significant differences among three fertilizer levels. 5. Growth, botanical composition, regrowth and yield of grasses grown under pine trees were significantly influenced by N fertilizer level, regardless of $P_2O_5\;and\;K_2O$. The fertilizer level of $N-P_2O_5-K_2O$ was 28-20-24 kg per 10a for more forage production in the forest. Considering economic yield in this study, however, the optimum fertilizer level of N, $P_2O_5\;and\;K_2O$ was suppose to be 21-28, 10-15, and 12-18kg per 10a, respectively.

• Korean Journal of Soil Science and Fertilizer
• /
• 제30권2호
• /
• pp.99-107
• /
• 1997

The effect of easily decomposable organic carbon (methanol) application on the behavior of nitrogen derived from surface-applied urea in submerged soil was investigated. Two rates of urea (150 & $300kg-N\;ha^{-1}$) and three levels of methanol (2, 4, 8 ml) were applied to 10 g soil samples. The samples were incubated for 30 days under submerged conditions. The flood water and the soil were sampled for analysis of urea-N, $NH_4-N$ and $NO_3-N$ every 10 days. Urea-N in flood water and in soil at the rate of $150kg-N\;ha^{-1}$ and that in flood water at the rate of $300kg-N\;ha^{-1}$ were not detected but the urea-N concentration in soil at the rate of $300kg-N\;ha^{-1}$ with 8 ml methanol treatment was 4.7 on the 10th day from incubation. $NH_4-N$ concentrations in flood water and in soil increased with increasing urea application rates whereas they decreased with increasing methanol treatment. $NO_3-N$ concentration in flood water and in soil were similar regardless of the urea and methanol application rates. The total amount of $NH_4-N$ in flood water and in soil decreased with increasing methanol treatment, 0 ml & 2 ml, whereas the total amounts of $NO_3-N$ in both flood water and soil increased slightly at higher rates of methanol treatment, 4 ml & 8 ml. The total amount of $NH_4-N$ in both flood water and soil increased up to 20 days of incubation whereas that of $NO_3-N$ in flood water and in soil decreased over incubation time.

• Korean Journal of Agricultural Science
• /
• 제20권2호
• /
• pp.103-108
• /
• 1993

This experiment was conducted to study the effects of pre-cultivation of chines milk vetch (Astragulas sinicus L.) on rice (Oryza sativa L, cv. Daecheongbye) growth and development. This experiment treatments were conducted by eight ; control 1 (stardard fertilizer ; N:P:K=0.3:0.2:0.2g/pot), control 2 (none fertilizer), root of C.M.V (chines milk vetch), shoot of C.M.V, whole plant of C.M.V, and root, shoot and whole plant of C.M.V+fertilizing N. Plant hight of rice was more than that control 1 in maximum tillering stage, heading stage and ripening stage. Tillering numbers per hill were the most in whole plant of C.M.V+fertilizing as whole growth and development period. And panicle per hill, spikelet per paincle, filled grain ratio and 1,000 grain weight were more in fertilized C.M.V than those control 1.

• Korean Journal of Plant Resources
• /
• 제9권3호
• /
• pp.261-267
• /
• 1996

This experiment was carried out to investigate the effects of various fertilizers on the growth and yield of tree peony Moutan cortex RADICIS from 1990 to 1994. The paeonol content, a main medical ingredient of tree peony, was 0.5% in the control, and the contents of the chemical fertilizer(N-P-K) and the two-kind compound fertilizer treatments were $0.26{\sim}0.41%$, and those were lower than $0.40{\sim}0.45$ of the compost, the fowl dropping manure and the organic fertilizer treatments. The weights off dry root(radix) rind were increased by 42% in the fowl dropping manure treatment and by 49% in the compost treatment compared with 151kg/10a in the control. All things considered, compost, fowl dropping manure and organic fertilizer were more effective than chemical fertilizers for the culture of tree peony.

• Journal of Korean Ophthalmic Optics Society
• /
• 제14권1호
• /
• pp.31-38
• /
• 2009

Purpose: This study was to evaluate corneal topography, contrast sensitivity and ocular response of a RGP, back surface aspherical contact lens compared with a spherical contact lens. Methods: A total 37 subjects were fitted with a spherical lens in right eye and an aspherical in the left eye and were evaluated for changes in corneal topography and contrast sensitivity over a 2-month period. Results: Thirty-four of 37 subjects completed the 2-month study. The corneal topography did not show differences between spherical and aspherical RGP lenses. The eyes fitted with the aspherical lenses demonstrated a greater reduction in contrast sensitivity compared with their spherical counterparts under photopic condition. Subjects preferred comfort and ocular responses provided by the spherical lens. Conclusions: Corneal topography when comparing spherical and back surface aspherical RGP lenses did not show any significant difference in the subjects. Spherical RGP lens yields better contrast sensitivity and preference than aspherical RGP lens at photopic condition. Further investigation of aberrations induced by contact lens design is warranted to explain the observed differences in visual performance.