• Proceedings of the Korea Air Pollution Research Association Conference
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• 1999.10a
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• pp.428-429
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• 1999

잘 알려져 있듯 광화학 오존 생성의 첫 단계는 N $O_2$가 자외선을 받아 NO와 O로 해리되는 과정이다. N $O_2$ ＋ h$\upsilon$ $\longrightarrow$ NO ＋ O 일반적으로 이러한 광해리 반응을 정량화하기 위하여 아래의 식과 같이 광해리 상수, $J_{NO2}$를 정의한다.(중략)략)

• East Asian Economic Review
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• v.23 no.2
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• pp.149-168
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• 2019

Public information arrivals and their immediate incorporation in asset price is a key component of semi-strong form of the Efficient Market Hypothesis. In this study, we explore the impact of public information arrivals on cryptocurrency market via Twitter posts. The empirical analysis was conducted through various methods including Kapetanios unit root test, Maki cointegration analysis and Markov regime switching regression analysis. Results indicate that while in bull market positive public information arrivals have a positive influence on Ripple's value; in bear market, however, even if the company releases good news, it does not divert out the Ripple from downward trend.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.34 no.1
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• pp.91-98
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• 2016

In order to apply Kriging methods for geostatistics of spatial data, an estimation of spatial coherency functions is required priorly based on the spatial distance between measurement points. In the study, the typical coherency functions, such as semi-variogram, homeogram, and covariance function, were estimated using the national geoid model. The test area consisting of 2°×2° and the Unified Control Points (UCPs) within the area were chosen as sampling measurements of the geoid. Based on the distance between the control points, a total of 100 sampling points were grouped into distinct pairs and assigned into a bin. Empirical values, which were calculated with each of the spatial coherency functions, resulted out as a wave model of a semi-variogram for the best quality of fit. Both of homeogram and covariance functions were better fitted into the exponential model. In the future, the methods of various Kriging and the functions of estimated spatial coherency need to be studied to verify the prediction accuracy and to calculate the Mean Squared Prediction Error (MSPE).

• Journal of the Society of Naval Architects of Korea
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• v.43 no.2 s.146
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• pp.147-155
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• 2006

Ice resistance estimation equations based on model tests and full-scale sea trial data from many previous research articles are studied. Measured ice resistance data and its empirical/semi-empirical estimation equations are summarized in common format and are compared with each other, considering three ship categories, i.e, icebreakers, tug/supply vessels, ice-strengthened cargo vessels. The most suitable estimation methods or prediction equations are recommended based on this ice resistance data analysis.

• Bulletin of the Korean Chemical Society
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• v.17 no.12
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• pp.1112-1117
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• 1996

The electronic structures of twenty-seven isomers of a macrocyclic fulleropyrrolidine are investigated with semi-empirical extended Huckel (EH) molecular orbital method. The geometry of each isomer is determined by the molecular mechanics and dynamics methods based on UFF (universal force field) empirical force field. The calculated geometries, such as the carbon-carbon distances of the fullerene moiety, are in good agreement with those of related fullerene derivatives. The EH calculation shows that the formation of macrocyclic pyrrolidine ring on fullerene moiety results in the reduction of the HOMO-LUMO energy gap. From the graphical analysis of the DOS (density of states), PDOS (projected DOS), and MOOP (molecular orbital overlap population) curves, we can find that this reduction is due to splitting of the HOMO of fullerene moiety, which results from the symmetry-breaking and the distortion of the buckminsterfullerene framework from its ideal icosahedral structure.

• Structural Engineering and Mechanics
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• v.77 no.2
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• pp.273-291
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• 2021

The strut-and-tie method (STM) has been widely accepted and used as a rational approach for the design of disturbed regions ('D' regions) of reinforced concrete members such as in corbels and deep beams, where traditional flexure theory does not apply. This paper evaluates the applicability of the equilibrium based STM in strength predictions of deep beams (with rectangular and circular cross-section) and corbels using the available experiments in literature. STM is found to give fairly good results for corbel and deep beams. The failure modes of these deep members are also studied, and an optimum amount of distribution reinforcement is suggested to eliminate the premature diagonal splitting failure. A comparison with existing empirical and semi empirical methods also show that STM gives more reliable results. The nonlinear finite element analysis (NLFEA) of 50 deep beams and 20 corbels could capture the complete behaviour of deep members including crack pattern, failure load and failure load accurately.

• Journal of the Korean Chemical Society
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• v.39 no.3
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• pp.150-156
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• 1995

Molecular orbital calculations at the ab initio, AM1, and PM3 levels have been carried out to investigate the lactam-lactim tautomerism of 1,2,4-triazolidine-3,5- dione(1) and 1,3,4-oxa(or thia)diazolidine-2,5-dione(2, 3). Most stable tautomer in 1 compound has been calculated to be a dilactam 1a and next one is lactam-lactim 1b. The relative energies between 1a and 1b are 4.1~12.6 kcal/mol depending on computational methods. The optimized 1a structure at ab initio level is in good agreement with X-ray structure. While the stabilities of 2 tautomers are in order of 2a>2b>2c, the stabilities of 3 tautomers are dependent on methods. According to 3-21G basis set, 3a tautomer is more stable by 4.9 kcal/mol over 3b tautomer. In contrast, the heat of formation of 3a at AM1 is higher by 2.71 kcal/mol than 3b.

• Structural Engineering and Mechanics
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• v.10 no.4
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• pp.371-392
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• 2000

Application of "advanced analysis" methods suitable for non-linear analysis and design of steel frame structures permits direct and accurate determination of ultimate system strengths, without resort to simplified elastic methods of analysis and semi-empirical specification equations. However, the application of advanced analysis methods has previously been restricted to steel frames comprising only compact sections that are not influenced by the effects of local buckling. A concentrated plasticity method suitable for practical advanced analysis of steel frame structures comprising non-compact sections is presented in this paper. The pseudo plastic zone method implicitly accounts for the effects of gradual cross-sectional yielding, longitudinal spread of plasticity, initial geometric imperfections, residual stresses, and local buckling. The accuracy and precision of the method for the analysis of steel frames comprising non-compact sections is established by comparison with a comprehensive range of analytical benchmark frame solutions. The pseudo plastic zone method is shown to be more accurate and precise than the conventional individual member design methods based on elastic analysis and specification equations.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.16 no.3
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• pp.54-62
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• 2017

When gears mesh, shock and noise are produced as results of tooth error and tooth deformation under load. Transmission error (TE) is the most important cause of gear noise and vibration because TEs affect the changes of the force and the speed of gears. Gear tooth modification research plays a positive role in reducing TE and improving the design level and transmission performance of transmission systems. In high-precision manufacturing gear, gear tooth modification is also commonly used to reduce noise in practical applications. In order to study the accuracy of gear transmission, some empirical gear profile micro-modifications are introduced, and a helical gear pair is modeled and analyzed in RomaxDesigner software to investigate the utility of these modification methods. Some of these will be selected as experimental proposals for gear pairs, and these manufactured gears will be tested and compared in a semi-anechoic room later. The final purpose of this study is to find reasonable and convenient empirical formulae to facilitate improved gear production.

• Proceedings of the KIEE Conference
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• 2002.07c
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• pp.1603-1605
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• 2002

TFT-LCD is widely used for flat panel display. The large-size TFT-LCD panel requires a high speed driving and various driving methods because of signal delay, which is responsible for the shading effects. In this work, the floating and double driving methods are applied to Pixel Design Array Simulation Tool(PDAST) and the pixel characteristics of TFT-LCD array is simulated. Also, we have implemented the semi-empirical TFT model to PDAST, which makes to obtain a more accurate pixel characteristics.