모드 해석 방법의 절차 개발 과정 소개 및 해석 결과 비교 (MODAL, FRF, KE)

조현성(Hyunsung Jo),최재영(Jaeyoung Choi),선광상(Kwangsang Seon),박상근(Sangkeun Park) 한국자동차공학회 2022 한국자동차공학회 부문종합 학술대회 Vol.2022 No.6

During vehicle structural analysis with CAE (Computer Aided Engineering) method using FEM (Finite Element Method), the first one is the MODAL analysis. For the detail of MODAL analysis, I will explain at main chapter. The more Degree of Freedom is used in MODAL analysis, The more real flexible body motion, it have. But it needs to use more memory for the process of analysis. So, in commercial program, the Lanczos method is preferred for proceeding of mode analysis with quickly and efficiently. Using this method, it is possible to set the desired frequency interval and it can specify the number of modes you want to see. Especially, it is possible to view and evaluate natural frequency values from low-order modes such as First mode and Second mode, which are the main interests of the user, and dynamic behavior in that mode in a short time. However, as the number of parts used in the analysis model increases, it is difficult to find an accurate mode value only in the region of interest. This is because the modes of multiple parts come together with the same mode value. Especially, if the dynamic behavior you want to see is a vibration caused by a specific part, mode analysis alone is not enough. Therefore, the FRF (Frequency Response Function) method is used, which is easy to see the behavior of a particular mode of interest only, but cannot see the dynamic behavior of the mode, and it is impossible to numerically compare exactly what percentage of the mode of the desired part. Therefore, the KE (Kinetic Energy) method is used which shows exactly how much percentage each part accounts for in each mode in total mode, so it is easy to find the desired mode, and then, through mode analysis, it is possible to immediately check whether it is the desired mode or not. Therefore, in the end, for accurate mode analysis, it was previously evaluated in only one method through MODAL analysis, but now all three additional methods need to be analyzed.

Modal Auxiliary Verbs in Japanese EFL Learners' Conversation: A Corpus-based Study

Nakayama, Shusaku Institute for Corpus Research 2021 Asia pacific journal of corpus research Vol.2 No.1

This research examines Japanese non-native speakers' (JNNS) modal auxiliary verb use from two different perspectives: frequency of use and preferences for modalities. Additionally, error analysis is carried out to identify errors in modal use common among JNNSs. Their modal use is compared to that of English native speakers within a spoken dialogue corpus which is part of the International Corpus Network of Asian Learners' English. Research findings show at a statistically significant level that when compared to native speakers, JNNSs underuse past forms of modals and infrequently convey epistemic modality, indicating the possibility that JNNSs fail to express their opinions or thoughts indirectly when needed or to convey politeness appropriately. Error analysis identifies the following three types of common errors: (1) the use of incorrect tenses of modal verb phrases, (2) the use of inflected verb forms after modals, and (3) the non-use of main verbs after modals. The first type of error is largely because JNNSs do not master how to express past meanings of modals. The second and third types of errors seem to be due to first language transfer into second language acquisition and JNNSs' overgeneralization of the subject-verb agreement rules to modals respectively.

정태동사 ‘會·能·可以’의 의미분석과 사용양상 연구

윤상희 중앙대학교 외국학연구소 2021 외국학연구 Vol.- No.58

Based on the analysis of conversational sentences in Chinese textbooks ‘New Hanyu Kouyu’, this paper points out the reasons why Chinese learners are confused with ‘會(Hui)’, ‘能(Neng)’ and ‘可以(Keyi)’. In the grammar aspect which means the meaning of ‘possibility’ and the meaning of ‘will’, ‘Hui, Neng, Keyi’ known as ‘Auxiliary Verb’ are not very different from each other. but they are different from each other in the ‘Modality’ aspect. Modal verb ‘能(Neng)’ includes ‘Epistemic Modality’, ‘Deontic Modality’ and ‘Dynamic Modality’ all. But modal verb ‘會(Hui)’ doesn’t include ‘Deontic Modality’ and modal verb ‘可以(Keyi)’ doesn’t include ‘Epistemic Modality’. In the ‘Modality’ aspect the main meaning of ‘能(Neng)’ is ‘possibility’ of ‘Dynamic Modality’, the main meaning of ‘會(Hui)’ is ‘conjecture’ of ‘Epistemic Modality’ and the main meaning of ‘可以(Keyi)’ is ‘permission’ of ‘Deontic Modality’. The main reason why learners can’t distinguish clearly in the modal verbs ‘會(Hui)’, ‘能(Neng)’ and ‘可以(Keyi)’ is that in Chinese conversation sentences have similar meaning and usage. Therefore each commonality and difference of the modal verbs ‘會(Hui)’, ‘能(Neng)’ and ‘可以(Keyi)’ will be clearly recognized only when explain in terms of ‘Modality’ which reveal the speaker's subjectivization.

표상 유사성 분석을 이용한 감각양상에 따른 정서표상 모델과 정서가 모델의 검증

김현중,김종완 한국감성과학회 2023 감성과학 Vol.26 No.2

Among the discussions on affective representation, the first is to explain the affective representation in the dimensions, and the second is to explain the affective representation according to the modality. In previous studies, to explain affective representation, valence models (signed valence, unsigned valence) and Modality-generality models (modality-general, modality-specific) were presented. In this study, we compared models presented in the previous study using the recently published ASMR to confirm which models explain affective representation well. The data used in this study were behavioral rating values collected by Kim & Kim (2022), and these were obtained for ASMR stimuli that were divided into three affective types (negative, neutral, and positive) and two modalities (auditory and audiovisual). Then, a multidimensional scaling, a representational similarity analysis with a two-way repeated measures ANOVA, and a multiple regression analysis with a two-way repeated measures ANOVA were performed. The results revealed that signed valence and modality-general distinguished between affective types of stimuli better than unsigned valence and modality-specific. Similar to the results of multidimensional scaling, the results of a representational similarity analysis and a multiple regression also showed that the signed valence and modality-general significantly explained affective representation better than the unsigned valence and the modality-specific. These results suggest that the model in which positive and negative are located at the opposite ends of the one dimension explains the affective representation of ASMR well, and that the affective representation was consistent regardless of modality. 정서표상에 대한 논의 중 첫 번째는 정서가 차원에서의 정서표상, 두 번째는 감각양상에 따른 정서표상을 설명하는 것이다. 선행연구에서는 정서표상을 설명하기 위해 정서가 모델(부호 정서가, 비부호 정서가), 감각양상에 따른 정서표상 모델(감각보편성, 감각특징성)들이 제시되었다. 본 연구에서는 최근에 등장한 ASMR을 이용하여 기존 연구에서 제시된 모델들을 비교하여 어떠한 모델이 정서표상을 잘 설명하는지 확인하고자 하였다. 본 연구에서 사용한 자료는 Kim & Kim(2022) 에서 수집한 3개의 정서유형(부정, 중립, 긍정) 및 2개의 감각양상(청각, 시청각)으로 구분된 ASMR 자극에 대한 정서평정자료를 사용하였다. 이후, 해당 자료에 대한 다차원척도법, 표상 유사성 분석 및 이원 변량분석, 다중회귀분석 및 이원 변량분석을 실시하였다. 다차원척도법 결과, 비부호 정서가에 비해 부호 정서가, 감각특징성에 비해 감각보편성에서 자극의 정서유형 간 구분이 잘 이루어졌다. 다차원척도법 결과와 유사하게, 표상 유사성 분석 및 다중회귀분석 결과 또한 비부호정서가에 비해 부호 정서가, 감각특징성에 비해 감각보편성이 유의하게 정서표상을 잘 설명하였다. 이러한 결과는 정서가모델 중 1차원의 양극단에 긍정과 부정이 위치하는 모델이 ASMR에 대한 정서표상을 잘 설명하며, 감각양상과 상관없이정서표상이 일관적임을 시사한다.

Dynamic Analysis of Hybrid Wind Power Composite Blades according to Stacking Properties Method

강병윤,문병영,한정영,홍철현 한국정밀공학회 2012 International Journal of Precision Engineering and Vol. No.

The purpose of this study is to supply an analysis tool for Buckling Analysis and Modal Analysis on hybrid blade for large wind turbine by using Finite Element Analysis. Equivalent Property Method, in which a single ply is assumed according to Classical Lamination Theory, and Stacking Property Method, in which the stacking order and the thickness are considered,was applied to conduct Finite Element Analysis. In addition, glass-epoxy and carbon-epoxy, the two materials applied to the shear web and the spar cap to make blades lighter, were used to compare the analysis results. Therefore, it is regarded efficient that rather than inconvenient employing Equivalent Property Method to find out equivalent properties every time, it would be better to use Stacking Property Method because the input is intuitive and various values including various stresses according to different stacking are available. As for Buckling Analysis, Stacking Property Method was employed based on the result of Modal Analysis and Fluid-structure Interaction Analysis was used. Both carbon-epoxy and glass-epoxy showed enough safety factors of the first modal values.

양태 표현을 활용한 감성분석

장지원(Jang Ji-won),김지은(Kim Jee-Eun) 한국외국어대학교 영미연구소 2017 영미연구 Vol.39 No.-

본 연구는 감성어를 포함하고 있는 영어 문장의 극성값에 영향을 미치는 양태 표현들을 감성분석에서 활용할 수 있도록 분석하고 분류한다. 양태 표현은 화자가 취하는 다양한 의미론적 태도를 드러내는 문법적 요소이다. 양태 특유의 속성상 양태화된 문장의 의미는 정확히 해석하기가 쉽지 않고 양태 표현을 통해 나타나는 감정가치 또한 정확히 분석하는 데 어려움이 있는 것이 사실이다. 그러나 양태 표현이 문장에서 화자의 감성을 표현·해석하는 데 핵심적 방법이자 단서가 되므로 감성가치에 영향을 미치는 양태 표현을 분류하고 분석하는 작업은 감성분석의 중요한 연구과제일 수밖에 없다. 본 연구에서는 감성분석의 정확 도를 향상시키기 위해 영화 리뷰 데이터에서 양태 표현을 포함하고 있는 문장을 수집하여 분석하고 분류하였다. 데이터 분석을 통해 양태동사를 포함하고 있는 표현의 유형, 문장 내의 문맥 구성요소, 계산된 극성값 등을 기준으로 양태 표현을 분류했다. 본 연구는 선행연구에서 다루지 않았던 양태 표현들을 분석했을 뿐 아니라 이를 포함하고 있는 문장의 극성값을 판단하여 감성분석에 적용할 수 있는 토대를 마련했다는 점에서 감성분석 시스템의 질적 향상에 기여할 것이다. This research presents a classification of English modal expressions which affect polarity values in sentiment analysis. Modality, commonly encountered in sentences, conveys various semantic attitudes of a speaker. Because of its special characteristics, the meaning of a modalized sentence is challenging to be correctly interpreted. The sentiment expressed with modal expressions is also difficult to evaluate. In order to increase the accuracy in evaluating sentiment values, modal expressions are collected from movie reviews and analyzed with selected linguistic cues to classify. The classification includes the expressions, its contextual components to co-occur, and the resulting sentiment value. Since it also lists up the classes which have not been dealt with in previous studies, it is expected to contribute performance improvement of a sentiment analysis system.

핵연료집합체 3 차원 축소모델 개발 및 모드해석

무하마드 수반(Muhammad Subhan),남궁인(Ihn Namgung) 대한기계학회 2021 대한기계학회 춘추학술대회 Vol.2021 No.4

APR1400 원전의 지진해석은 집중질량 빔요소로 구성된 2 차원 모델로서 수직 방향과 수평 방향 모델로 분리되어 있다. 원자로 코어의 모든 핵연료는 모두 합쳐져서 몇 개의 빔요소와 집중질량으로 모델이 이루어져 있다. AP1000의 경우에는 3 차원 집중질량과 빔요소를 사용하여 모델을 개발하였으며, 3 차원 지진해석을 수행하였다. 본연구의 목적은 노심의 핵연료집합체를 통합하지 않고 개별 핵연료집합체에 대한 축소 동해석 모델을 개발하여 노심 동해석을 가능하게 하는 것이다. 이를 위해 본 논문에서는 최신 컴퓨터 기술 및 모델링 기술을 접목해서 핵연료집합체의 3 차원 동해석 방법론을 개발하는 것이다. 3 차원 핵연료 집합체의 축소모델을 개발하기 위해 핵연료봉은 질량으로 나타냈고, CEA 가이드 튜브와 스페이서 그리드는 빔요소를 사용하였고, 하단지지체와 상단지지체는 쉘요소로 취급하여 전체적으로 축소된 모델을 개발하였다. 이렇게 개발된 축소모델은 2,740 개의 요소와 5,148 개의 요소를 가진다. 이 모델에 대해 모드해석을 하여 시험결과와 비교를 통해 1 차모드를 수렴하도록 하였다. 모드해석을 통해 2 차, 3 차 및 4 차 모드도 시험 결과와 유사한 경향을 보임을 확인하였다. 따라서 본 축소모델을 사용하여 지진해석 및 시간이력해석이 가능할 것으로 판단된다. 본 연구에서 모드해석 결과 기존의 통합 모델에서 관찰할 수 없던 트위스트 모드를 보였다. 이 결과는 핵연료사이의 접촉가능성을 보여주는 것으로서 핵연료 사이의 동적 거동에 대한 추가적인 연구가 필요하다. Currently, the seismic analysis model of APR 1400 consists of beam and lumped mass in 2D separated model in horizontal direction and vertical direction. Also in the core, fuel assemblies are aggregated and simplified into few beam and lumped masses. WEC also used beam and lumped mass elements for the AP1000 seismic analysis model, but used 3D beam and mass to represent whole core where fuel assemblies are aggregated as well. The main purpose of the lumped mass and beam modeling of fuel assembly is to simplify model and make core dynamic analysis possible without aggregating all fuels in core into few beam elements and lumped masses. This research investigates 3D dynamic analysis modeling methodology of nuclear fuel assembly reflecting performance improvement of computer technology and analysis software functionality. A 3D modeling approach of FA was proposed in which fuel rods mass was lumped, CEA guide tubes and spacer grid are represented by beam elements and lower end-fitting and upper end-fitting are represented by shell elements. The FA dynamic analysis model so developed consists of 2,740 elements and 5,148 nodes. The model was optimized for the 1st mode from the test results of FA applying modal analysis. The model was successfully represents 1st mode modal values. Also the modal analysis results exhibits similarities for 2nd, 3rd and 4th modes, hence the model can be used for further dynamic analysis of fuel assembly such as seismic analysis or time-history analysis. The corresponding mode shapes revealed additional mode of twist motion that was not shown by current FA dynamic model of APR1400 or AP1000. This research revealed there are extra modes of twist motion that could induce contact between FAs and would require further investigation of dynamic interaction between FAs.

Analytical and Experimental Modal Analysis of Electrical Transmission Tower to Study the Dynamic Characteristics and Behaviors

Chiranjit Bhowmik,Prasun Chakraborti 대한토목학회 2020 KSCE Journal of Civil Engineering Vol.24 No.3

Experimental modal analysis of electrical transmission tower has been a challenging task for transmission tower researchers and design engineers in industry all over the world. Requirement of large numbers of sensors and accelerometers have been major constrain. In this study an innovative approach has been developed to investigate the dynamic characteristics and behavior of tower structure through analytical and experimental modal analysis. Firstly, a scale down (1:15) prototype model of transmission tower structure has been constructed with mild steel straps, joint together by welding, for modal testing. Modal hammer test has been conducted on the prototype tower model for extracting modal parameters; modal frequency, modal damping and modes, of the tower model which representing the actual tower structure. Secondly, the transmission tower structure has been modeled in standard finite element tools and analyzed analytically for natural frequencies. The first six natural frequencies and corresponding mode shapes have been determined analytically and first six natural frequencies have also been determined experimentally and compared with each other. The first six natural frequencies are determined analytically, the frequency range of 2–9 Hz has been found. The analytical and experimental modal analysis of transmission tower structure has been found to be in correlation with some differences. The maximum natural frequencies percentage difference 11.1% has been found; between the scale down model and the stand software model. Additionally, the tower structure has been modified and optimized to improve the stiffness of the diaphragm as per specification and practical limitations. The first order natural frequency of the modified tower has been reduced to 2.171 Hz from the 2.1773 Hz.

Crack development assessment using modal analysis in peridynamic theory

Andris Freimanis,Ainars Paeglitis 한국CDE학회 2021 Journal of computational design and engineering Vol.8 No.1

If structural damage remains undetected and is allowed to grow, structure’s load-bearing capacity deteriorates, which can lead to costly repairs or in extreme cases its collapse. Modal analysis is widely used to detect structural damage because, when damage, such as cracks, is introduced, structure’s geometrical and/or mechanical properties change, and these changes can be used for damage detection. Peridynamics is a non-local alternative to the continuum mechanics theory that represents forces and displacements using integral equations, which are defined even with discontinuous displacement fields, thus making this theory an attractive option for damage modeling. In this paper, authors verify peridynamic (PD) modal analysis against finite-element (FE) results, and validate it against experimental modal analysis results. The modal solver was implemented in the open-source program Peridigm and four different damage configurations were considered for verification and validation. The results show close agreement between the PD and the FE results, and the PD and the experimental results. Moreover, PD modal frequencies are shown to have similar accuracy to experimental data as the FE results. It is also shown that the frequency shifts are comparable between all three types of modal analysis. The PD mode shapes agreed well with both the FE and the experimental mode shapes at all considered damage configurations. Furthermore, the change in mode shapes from the introduced damage is similar in all three analyses.

삼각배열을 갖는 사각다공평판의 유효탄성계수 평가

정경훈(Kyeong-Hoon Jeong),정명조(Myung-Jo Jhung),김종욱(Jong-Wook Kim) 한국소음진동공학회 2015 한국소음진동공학회 학술대회논문집 Vol.2015 No.4

A theoretical modal analysis for a perforated rectangular plate with a fixed boundary condition and a triangular penetration pattern, is suggested. The natural frequencies of the perforated plate gradually decrease with a hole size, because the structural stiffness of the perforated plate is reduced severely than mass inertia according to increase of hole size. In the study, the natural frequencies of the perforated square plate are obtained as a function of ligament efficiency using commercial finite element analysis code, ANSYS. Additionally they are used to extract the effective modulus of elasticity under an assumption of constant Poisson’s ratio. The effective modulus of elasticity for the fully perforated square plate is applied to modal analysis of a partially perforated rectangular plate using a homogeneous finite element analysis model. The natural frequencies and the corresponding mode shapes of the homogeneous model are compared with the results of the detailed finite element analysis model of the partially perforated rectangular plate in order to check the validity of the effective modulus of elasticity. In addition, theoretical method to calculate the natural frequencies of a partially perforated rectangular plate with fixed edges is suggested according to the Rayleigh-Ritz method. The suggested effective modulus of elasticity can be applicable to the perforated plates of reactor internal structure which will reduce the finite element analysis model size and contribute an effective modal analysis and seismic analysis based on the finite element analysis.