• Journal of Korean Ophthalmic Optics Society
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• v.4 no.2
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• pp.23-31
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• 1999

The purpose of this study is to evaluate the relationship between axial length/corneal radius ratio and refractive error for human eye. Ocular components were measured Baush & Lomb keratometer, Holden-Payor pachometer, and Stoz Compuscan. Refractive error was measured by subjective refraction. The results were as follows; 1) Spherical equivalent refractive error and axial length/corneal radius ratio was very highly correlated with the correlation coefficient for -0.89. 2) Axial length/corneal radius ratio and axial length, vitreous chamber depth were highly correlated that the correlation coefficients were 0.82, 0.80 respectively. 3) Axial length/corneal radius ratio and anterior chamber depth, corneal power, corneal radius, lens power were correlated with the correlation coefficients for 0.57, 0.40, -0.39, -0.35 respectively. 4) There were no significant correlation between axial length/corneal radius ratio and lens thickness, and corneal thickness.

• Korean Journal of Optics and Photonics
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• v.15 no.1
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• pp.12-16
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• 2004

We show that the extinction ratio is improved using slight asymmetry in two core refractive indices of polarization independent very short vertical directional couplers with the double-sided deep-ridge (DSDR) waveguide structure. The optimum asymmetry with the maximum extinction ratio and the tolerance of the refractive index of core with the extinction ratio larger 1ha]1 30 ㏈ increase as the thickness of inner cladding layer and the two cores decrease due to the increase of the coupling strength between the two cores. Also, the device length and the tolerance of the device length with the extinction ratio larger than 30 ㏈ decrease as the thickness of the inner cladding layer and the two cores decrease due to the increase of the coupling strength between the two cores. We show that polarization independent vertical directional couplers with the DSDR waveguide structure with the device length less than 100 ${\mu}{\textrm}{m}$ and the extinction ratio larger than 30 ㏈ could be implemented.

• Journal of the Korean Society of Food Science and Nutrition
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• v.29 no.5
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• pp.843-848
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• 2000

The single cell-gel electrophoresis assay (comet assay) was used to identify irradiated beans. Soy beans, kidney beans, and red beans were irradiated with $^{60}Co$ gamma rays at 0.1, 0.3, 0.5, 0.7, and 1.0 kGy. Beans were peeled out, crushed lightly, and treated with phosphate-buffered saline (PBS) to extract cells. The extracted cell suspension was mixed with agarose gel solution and spread on an agarose precoated slide. After lysis of the cells, they were subjected to microgel electrophoresis for 2 minutes, and then silver-stained. We found that the DNA fragments of the irradiated samples were stretched, migrated out of the cells, and formed tails towards the anode giving the appearance of comets, while the unirradiated or the undamaged cells formed very short or no tails. The tail lengths of irradiated samples were significantly increased as irradiation dose increased at the above 0.3 kGy.

• Journal of Energy Engineering
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• v.23 no.4
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• pp.256-262
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• 2014

Cycle length of domestic nuclear power plants is determined by the demand-supply plan of utility company. The target cycle length is achieved by adjusting the number of feed fuel assembly and fuel enrichment. Traditionally, utility company first select the number of feed fuel assembly and then find out the fuel enrichment to achieve the special cycle length. But it is difficult to find out if this method is most economical than any other combinations of the enrichment and batch size satisfying the same cycle length. In this paper, core depletion calculation is performed to find out the optimum combination of the enrichment and batch size for given target cycle length in terms of fuel cycle cost using commercial core design code; CASMO/MASTER code. To minimize the uncertainty resulting from transition core analysis, levelized fuel cycle cost analysis was applied to the equilibrium cycle core in order to determine the optimum combination. The sensitivity study of discount rate was also carried out to analyze the levelized fuel cycle cost applicable to countries with different discount rates. From the levelized fuel cycle cost analysis results, the combination with smaller batch size and higher fuel enrichment becomes more economical as the discount rate becomes lower. On the other hand, the combination with higher batch size and lower fuel enrichment becomes more economical as the discount rate becomes higher.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2010.11a
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• pp.555-558
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• 2010

This paper presents a design of solid rocket motor with high length to diameter applied composite propellant. Solid rocket motor with high L/D ratio can be generated erosive burning and combustion instability on longitudinal mode. Especially, Erosive burning can effectively prolong the initial pressure spike in some star grain motors. That is, the study shows design of grain, internal ballistics and structural analysis in order to perform system requirements.

• Journal of the Korean Society of Propulsion Engineers
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• v.7 no.2
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• pp.62-69
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• 2003

Swirl injectors have the advantage of stable combustion, high efficiency, and insensibility to variable O/F ratio. Recess length is the length from outer orifice tip to inner orifice tip. It is the very important variable of performance of swirl type injector Recess length have influence on collision, mixing, spray, and combustion of propellants. This study investigated on the engine performance with the change of recess length through CFD, cold flow test, and combustion test. In result, we could confirm the change of engine performance with the change of recess length. And we found that performance forecast process through CFD, cold flow test is the right process through combustion test.

• Journal of the Korea Institute of Building Construction
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• v.22 no.4
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• pp.359-370
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• 2022

Despite continuous efforts to reduce on-site safety accidents, the construction industry remains a high-risk sector with a high rate of fatal accidents. Design for Safety(DFS), which manages safety risk factors at the design stage, is being used as a method to lower the construction safety accident rate. However, due to limited knowledge, designers are unaware of the design-results risks during the different of the project lifecycle, including construction, operation, and maintenance. Effective DFS can be conducted if the designer understands the effect of the building shape on the safety accident rate and corresponding safety management cost(SMC). The cost of safety facilities such as fall prevention nets and safety fences will vary depending on the shape of the building. This study analyzes the outer perimeter length's impact on SMC. Following the data collection from 21 projects for this study, an analysis was conducted using the independent variables of the building perimeter(BP), building shape factor(BSF), and building area(BA), the dependent variable of SMC. The correlation R2 was found to be 0.876, 0.801 and 0.792 between the BP and SMC, BSF and SMC, BA and SMC, respectively, indicating that these factors were closely related.

• Proceedings of the Optical Society of Korea Conference
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• 2000.02a
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• pp.306-307
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• 2000

1962년 Armstrong 등에 의해 second harmonic generation(SHG) 의 이론이 완성된 후 SHG 효율을 높이기 위한 방법으로 비선형성이 큰 물질의 개발과 더불어 위상정합(phase matching)을 만족시키는 여러가지 방법이 연구 되었다. 특히 위상정합의 경우 지금까지는 복굴절을 이용하는 방법이 널리 사용되었으나 이 경우 입사광의 파장이 제한적이고, 많은 무기물 결정에서 비선형광학계수의 가장 큰 텐서 성분인 $d_{zzz}$를 사용할 수 없다는 단점을 가지고 있다. 반면 유사위상정합(Quasi-phase matching:QPM) 은 비선형광학계수( $d_{zzz}$)의 방향을 결맞음 길이(coherence length)마다 분극반전 시켜주어 2차 조화파의 진폭을 길이방향으로 계속 증가시키는 방법으로 구역반전된 길이를 조절하면 거의 모든 파장에 대해 비임계 위상정합( $d_{zzz}$ 사용)이 가능하고, 2차 조화파가 기본파의 전파경로에서 벗어나는 walk-off 현상이 없어 SHG 전환효율을 극대화할 수 있다. (중략). (중략)

• Korean Journal of Plant Taxonomy
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• v.31 no.4
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• pp.359-373
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• 2001

One of Korean Typha species has been used two scientific names, T. angustifolia L. and T. angustata Bory et Chaubard without taxonomic examinations. Typha angustifolia has a longer females flowers than bracteoles and equal length of bracteoles and hairs in female flowers whereas T. angustata has equal length of female flowers and bracteoles and longer bracteloes than hairs in female flowers. In this study, the pattern of morphological variation of T. angustifolia in Korea is examined using numerical analysis to determine their taxonomical identities. Univariate analysis using morphological characters such as female flower length/bracteole length and bracteole lengh/hair length reveals that Korean T. angustifolia is composed of one group. The result of principal components analysis shows that Korean T. angustifolia is closely related to T. angustifolia distributed in Japan, Russia, and USA. Therefore, T. angustifolia L. (in Korea) is suggested as a legitimate scientific name.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2010.11a
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• pp.55-62
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• 2010

In addition to the previous study for development of a 1,200 N-class bipropellant rocket engine with concentrated hydrogen peroxide, the effect of characteristic length and thrust measurement were experimentally evaluated. Tests with characteristic lengths of 0.95, 1.07, and 1.20 m were performed and $C^*$ and Isp efficiencies were increased as increasing characteristic length. The maximum $C^*$ and Isp efficiencies were 98.4% and 93.1% respectively. Based on the evaluation of the designed engine, the optimized characteristic length was proposed in using the engine adapted decomposed hydrogen peroxide and the engine performance at vacuum-level was evaluated using thrust and Isp efficiency at the designed equivalence ratio. As a result, 218.4 s at sea-level, 253.3 s at vacuum-level, and vacuum thrust of 1035.3 N can be estimated.