• The Proceeding of the Korean Institute of Electromagnetic Engineering and Science
• /
• v.4 no.2
• /
• pp.82-90
• /
• 1993

전자파에 의한 산란현상의 해석은 지금까지 주로 시간조화함수의 형태를 지닌 전원에 의한 정 상상태의 산란에 관하여 이루어졌다. 그러나 레이다나 피파괴 검사, 전송선로 점검 등의 응용에서는 주로 펄스형태의 전자파를 사용하며, 따라서 시간에 따라 변화하는 함수형태의 전원에 의한 전자파의 산란해 석이 중요한 문제로 등장하였다. 또한 통신선로에서 외부의 잡음에 대한 혼신 등을 해석하거나, 낙뢰가 송 전선로에 미치는 영향을 해석하는 데에도 펄스신호의 산란해석이 필수적이다. 일반적인 함수의 형태를 지닌 전원에 의한 산란현상을 해석하기 위해서는 전원함수를 Fourier 변환하 여 주파수 영역의 스펙트럼을 구하고, 주파수영역에서의 산란해를 이용하여 Fourier 역변환을 하여 시간 영역의 해를 구할 수 있다. 주파수 영역에서의 산란판의 해를 Fourier 역변환 하기 위해서는 적분을 행하여야 하며, 일반적으로 적분과정에서 매우 복잡한 계산이 필요하고, 산란체의 구조가 복잡하여 해석 적인 해를 구할수 없는 경우에는 해석적으로 시간영역의 해를 구하는 것이 불가능하다. 시변 함수에 의 한 산란파를 구하기 위한 수치해석적 방법으로는 모멘트방법이나 유한요소법(Finite Element Method), 경계요소법(Boundary Element Method), 유한차분법(Finite Difference Method)등이 있으며, 해석적 해 를구할 수 없는 경우에 적용할 수 있는 반면에 많은 계산량이 요구된다.

• Journal of Korean Tunnelling and Underground Space Association
• /
• v.19 no.2
• /
• pp.195-212
• /
• 2017

When back analysis is used for the assessment of an operating subsea tunnel safety in various measurement information such as stress, water pressure and tunnel lining and ground stiffness degradation, the reliable results within tolerable error rate can be obtained. By utilizing a commercial geotechnical analysis program FLAC3D, back analysis can be performed with a DEA which has already been successfully validated in previous studies. However, relative more time-consumption is the drawback of this approach. For this reason, this study introduced beam-spring model-based on FEM solver which uses less analysis time relatively. Beam-spring program capable of structural analysis of a circular tunnel section was developed by using Python language and combined with the built-DEA. From the measurement datum, expected to estimate the stability of an operation tunnel close to real-time.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
• /
• v.29 no.4
• /
• pp.329-341
• /
• 2011

The object of this paper is to compare the accuracy and the characteristic of various methods of solving the geodetic inverse problem for the geodesic lines which be in the standard case and special cases(antipodal, near antipodal, equatorial, and near equatorial situation) on the WGS84 reference ellipsoid. For this, the various algorithms (classical and recent solutions) to deal with the geodetic inverse problem are examined, and are programmed in order to evaluate the calculation ability of each method for the precise geodesic determination. The main factors of geodetic inverse problem, the distance and the forward azimuths between two points on the sphere(or ellipsoid) are determined by the 18 kinds of methods for the geodetic inverse solutions. After then, the results from the 17 kinds of methods in the both standard and special cases are compared with those from the Karney method as a reference. When judging these comparison, in case of the standard geodesics whose length do not exceed 100km, all of the methods show the almost same ability to Karney method. Whereas to the geodesics is longer than 4,000km, only two methods (Vincenty and Pittman) show the similar ability to the Karney method. In the cases of special geodesics, all methods except the Modified Vincenty method was not proper to solve the geodetic inverse problem through the comparison with Karney method. Therefore, it is needed to modify and compensate the algorithm of each methods by examining the various behaviors of geodesics on the special regions.

• Tunnel and Underground Space
• /
• v.15 no.5 s.58
• /
• pp.344-351
• /
• 2005

Direct back analysis software is coded based on Simplex method using FLAC as a subroutine. For the verification of the software, 12 different cases are assumed combining various displacements in different measuring locations around a tunnel. The number of displacements for cases varies from 3 to 240. It is verified that the exact elasticity and the primary stress state of rock around a tunnel could be found through iterative calculation regardless of the locations and number of displacements and initial values needed for the direct back analysis.

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2012.05a
• /
• pp.397-402
• /
• 2012

The objective of this study is the estimation of the two unknown thermal conductivity and thermal diffusivity by an inverse heat conduction analysis using the Levenberg-Marguardt method. One dimensional formulation of heat conduction problem in the model was applied. Two point transient temperature of test pieces and heat flux of inflow were measured under the high enthalpy flow environment. Estimated thermal conductivity and thermal diffusivity by an inverse analysis were compared with the known values of graphite test piece. It showed the effectiveness of proposed experimental inverse analysis.

• Journal of Korean Tunnelling and Underground Space Association
• /
• v.10 no.4
• /
• pp.397-404
• /
• 2008

Excessive amount of groundwater flowed into tunnel, while constructing Incheon international airport railway. Tunnel passes under subway line no. 2 with only 1.76 m below. To protect the existing structure, TRcM excavation method was applied. As station and construction shaft are already constructed, which are located back and forth of TRcM section, 86.4 ton per day of groundwater inflow is against expectation. To identify mechanism of excessive water inflow, hydraulic back analyses were performed. Then, hydro-mechanical coupled analysis were also performed with the hydrogeologic parameters identified, whose results are investigated for checking the stability of adjacent structures to the tunnel under construction. And a number of mechanical analyses were also performed to check the hydro-mechanical coupling effect. The result from the mechanical analysis shows that subsidence and tunnel ceiling displacement will be 0.85 mm and 1.32 mm. The result of hydro-mechanical couple analysis shows that subsidence and maximum tunnel ceiling displacement will be 1.2 mm and 1.72 mm. Additional displacements caused by groundwater draw down were identified, however, displacement is minute.

• Phonetics and Speech Sciences
• /
• v.13 no.2
• /
• pp.27-35
• /
• 2021

This study investigated the status of the wh-island constraint in Seoul Korean. The syntactic movement of a wh-phrase out of an embedded sentence so as to have wide scope at LF is known to be invalid as it violates the wh-island constraint, but there have been studies in which such a movement was possible when the sentence is read with a wh-intonation. We conducted perceptual tests in which subjects were asked to select an answer after listening to each of the four types of interrogative sentences. Three of them were with 'Nugu-leul', which is an accusative form of the wh-phrase 'who' as well as an indefinite form. The fourth sentence contained the name of a person. 'Nugu-leul' and the noun were positioned in the same embedded sentence to see whether the subjects accepted a matrix scope interpretation of the wh-phrases. Response time was transformed to normalized log response time and checked to find any differences in the time taken to select the answers depending on different types of interrogative sentences. The results showed the subjects had a definite preference for the matrix scope interpretation for the sentences with a wh-intonation. The response time required to select the matrix scope interpretation was longer than for any other type of interrogative sentence. We concluded that the wh-island constraint in Seoul Korean is weak.

• The Journal of the Convergence on Culture Technology
• /
• v.8 no.1
• /
• pp.403-408
• /
• 2022

This study analyzed the translation strategies of four Chinese translations of 『Who ate all the Sing a?』. As is well known, Park Wan-seo's works contain many psychological descriptions, abstract vocabulary, idioms, proverbs, dialects, etc., so when translating into Chinese, various translation strategies such as translation, interpretation, and creative translation are required. Although all four types studied in this paper are somewhat different depending on the translator, all translation strategies were used in a comprehensive way. As a result of the study, all four translation strategies used a strategy of direct translation of Chinese characters when translating geographical namesand names of people. The interpretational translation strategy was used for the translation of vocabulary that requires historical, social, cultural, and geography background interpretation. was utilized. The creative translation strategy was used when translating overlapping issues, political and historically sensitive issues, and issues related to Korean pronunciation and grammar. Based on the results of this study, it is expected that translation strategy research on various Chinese translations of Korean modern literature as well as various Chinese translations of Park Wan-seo will be expanded.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.34 no.4
• /
• pp.487-493
• /
• 2010

Most structural analyses are concerned with the deformations and stresses in a body subjected to external loads. However, in many fields, inverse problems have to be interpreted to determine surface tractions or internal stresses from displacements measured on a remote surface. In this study, the inverse processes are studied by using the finite element method for the evaluation of internal stresses. Small errors in the measured displacements often result in a substantial loss of stability of an inverse system. In order to improve the stability of the inverse system, the displacements on a section near the region of the unknown tractions are predicted by using orthogonal basis functions. We use the Gram-Schmidt orthogonal technique to determine two bases for the displacements on a section near the region of the unknown tractions. Advantages over previous methods are discussed by using numerical examples.

• Journal of Korean Association for Spatial Structures
• /
• v.11 no.1
• /
• pp.87-95
• /
• 2011

This study presents the comparisons between the analysis results based on membrane theory and finite element analysis for the inverted umbrella-type hyperbolic paraboloid shell structure. The effects of the roof angle on the roof deflections, member forces of edge beams and ribs, and shell stress are also investigated with various roof angles. Results show that the membrane theory overestimates the member forces of edge beams and ribs. On the contrary, the shell stresses are underestimated in the membrane theory when compared to the results from the finite element analysis. The deflections of roof slabs by finite element analysis show drastic increasement as the roof angle decreases.