Earticle

그레이스케일 수학적 형태학에 기초한 에지 검출 알고리즘의 방법은 영상 노이즈를 제거와 병렬처리 가능 하고 연산속도가 빠르다는 장점을 갖고 있다. 그러나 단일 구조적 스케일 요소를 사용하여 영상의 에지 검출을 하는 방법은 영상정보에 따라서 영향을 받을 수 있다. 그레이스케일 형태학의 특성은 구조적원소를 반복하여 확장, 침식, 열림, 담힘 연산을 함으로써 연산 결과 에지정보 결과에 제한적일 수 있다. 본 논문에서 잡음에 강인한 방향 성을 갖는 구조적원소를 적용한 후 원소내의 각 픽셀 정보에 가중치 엔트로피를 적용하는 에지 검출 알고리즘을 제안한다. 영상에 적용하는 멀티 스케일 구조적 요소를 적용한 결과와 방향성 가중치 엔트로피를 적용한 연산결과 를 비교분석하였으며, 시뮬레이션 결과는 제안된 알고리즘이 에지 검출에서 우수함을 보였다.

The method of the edge detection algorithm based on grayscale mathematical morphology has the advantage that image noise can be removed and processed in parallel, and the operation speed is fast. However, the method of detecting the edge of an image using a single structural scale element may be affected by image information. The characteristics of grayscale morphology may be limited to the edge information result of the operation result by repeatedly performing expansion, erosion, opening, and containment operations by repeating structural elements. In this paper, we propose an edge detection algorithm that applies a structural element with strong directionality to noise and then applies weighted entropy to each pixel information in the element. The result of applying the multi-scale structural element applied to the image and the result of applying the directional weighted entropy were compared and analyzed, and the simulation result showed that the proposed algorithm is superior in edge detection.

본 연구는 러시아어권 학습자들의 한국어 이중모음 발음에서 발생하는 오류들을 한국어와 러시아어의 음절구조의 차이와 구성원소 이론을 바탕으로 분석하는 것을 목적으로 한다. 러시아어권 학습자들에게한국어 이중모음 입력이 주어지면 학습자들은 러시아어의 모음 체계와 음절구조를 바탕으로 이를 재해석하고 조정하여 출력한다. 러시아어는 활음 /j/를 가지고 있어 한국어 /j/계 이중모음 습득에는 큰 어려움을 겪지 않는다. 주목할 만한 오류는 한국어 /w/계 이중모음 발화에서나타난다. 러시아어권 학습자들은 한국어의 /we/를 [e], [ue],[ve]로 발화하는 오류를 보인다. 그리고 이들은 한국어의 /wa/를 [a], [ua], [oa], [va]로, 한국어의 /wə/를 [o], [uo], [uə], [vo]로 발화하는 오류를 보인다. 이들은 각각 활음 탈락, 모음 분리, 자음 대치로 분석이 가능하다. 마지막으로 러시아어권 학습자들은 한국어의 /ɨj/를 [i], [ɨ], [ɨi]로 발화하는오류를 보인다. 이는 학습자들이 한국어 /ɨj/의 구조를 받아들이지 못한 것으로 각각 모음 삭제와 모음 분리로 분석할 수 있다.

Journal of the International Network for Korean Language and Culture 16-2. 149-169. This paper aims to analyze the errors made by Russian learners in producing Korean diphthongs based on differences in the syllable structures of the two languages and element theory. When Korean diphthongs input is given, Russian learners reanalyze and adjust it based on their internal representation of the Russian vowel system and syllable structure, as reflected in their output. As Russian has a glide /j/, Russian learners do not have much difficulty in producing the /j/ diphthongs of Korean. Notable errors appear, however, in producing /w/ diphthongs of Korean. Russian learners pronounce the Korean diphthong /we/ as [e], [ue], and [ve], /wa/ as [a], [ua], [oa], and [va], and /wɔ/ as [o], [uo], [uə], and [vo]. These errors can be classified as glide deletion, vowel separation, and consonant substitution, respectively. Finally, they produce [i], [ɨ], and [ɨi] for Korean /ɨj/, indicating that they do not grasp the structure of Korean /ɨj/ but realize it through vowel deletion and vowel decomposition.

In this paper, a method of reducing the weight of vehicle wheels through topology optimization by finite element method is proposed. Recently, various environmental pollution caused by the operation of vehicles is gradually increasing, and this has a great correlation with the fuel efficiency of the vehicle. Therefore, it is required to reduce the weight of the vehicle to increase fuel efficiency. Among them, the vehicle's wheels are a key part of vehicle acceleration and braking, and passenger safety. Because the shape of the wheels is different, various effects such as reduced fuel economy and reduced airpower occur as well as aesthetic factors. The stiffness of the wheels plays an important role in transmitting the vehicle's power to the tires and braking. In this study, to reduce weight while satisfying the stiffness value, we propose to use topology optimization to design an arbitrary shape according to the number of spokes on the wheel.

이 연구는 2015 개정 교육과정 초등 실과의 ‘로봇의 기능과 구조’ 내용 요소에서 로봇의 작동과 연계할 수 있는 소프트웨어가 갖추어야 할 요소와 소프트웨어의 실행에 적합한 로봇의 형태 그리고 로봇의 작동을 위한 명령어 구성 등에 관한 것으로, 2015 개정 교육과정에 따른 초등 실과 교과서 집필에 참고자료를 제공하기 위한 것이 연구의 목적이며, 결과는 다음과 같다. 첫째, 현재 교구 로봇을 작동시키기 위한 소프트웨어의 프로그래밍 언어 형태는 대부분 아이콘과 블록 기반으로 되어 있었으며, 일부는 텍스트 언어로 되어 있었다. 둘째, 교구 로봇의 작동에서 텍스트 언어로 된 명령어를 사용하여 프로그램을 작성하는 경우, 초등학생들에게는 어렵고 구문 에러가 발생할 수 있으며, 의도한 내용의 프로그램이 바르게 작성되지 않을 때 로봇 제어를 위한 프로그래밍은 어렵다는 인식을 갖게 할 수 있다고 판단되었다. 셋째, 소프트웨어와 연계하여 작동시키기 위한 로봇의 구성요소는 몸체, 제어장치, 감지장치, 구동장치, 전원장치, 주변장치가 각각 구분된 형태로 구성되어 있어야 하며, 몸체는 완전 조립이나 반조립 형태 보다는 학생들이 창의적 형태의 로봇을 스스로 조립할 수 있는 블록 조립형이 적절하며, 감지장치와 주변장치는 로봇의 몸체나 제어장치와 일체화된 형태 보다는 각각이 개별화된 형태가 로봇의 작동 원리나 센서의 기능을 더 효율적으로 이해할 수 있는 형태라고 판단되었다. 넷째, 교구 로봇 작동을 위한 소프트웨어는 명령어 블록을 드래그 & 드롭으로 프로그램을 작성할 수 있어야 하며, 프로그램을 작성하는 화면의 전환이나 프로그램의 다운로드 등과 같은 2차적 활동 없이 작성한 프로그램을 곧바로 실행하고 그에 따라 로봇이 작동되는 실시간 제어의 형태가 되어야 하며, 프로그램의 주 화면에는 로봇 작동 관련 명령어 블록을 각 장치를 범주로 구분하여 나타내고, 각 범주에서의 블록은 작동 관련 부품별로 부품명을 나타내는 문자와 색깔 등으로 구분하여 확실하게 이해할 수 있도록 해야 블록에 대한 직관성을 높일 수 있을 것으로 판단되었다. 다섯째, 로봇 작동을 위한 엔트리 소프트웨어의 초등 실과형을 평가한 교사들은 ‘로봇의 기능과 구조’ 내용 요소의 성취기준을 달성하고 효율적인 교수･학습이 이루어질 수 있게 구성･조직되었다고 평가하여 연구에서 제시한 소프트웨어는 적절한 형태였다고 판단되었다.

This research is to accomplish the standard of accomplishment about 2015 revised course of study of ‘function and composition of robot’ in elementary practical arts its efficiency. Also, it is about the operation of robot and software that can link elements it needs, acceptable form to operate the software, and the composition of command to operate a robot. The results are as follows. First, software’s programming language or form to operate robots in modern days are made mostly out of icons and blocks. Some are coded in text language. However, text language can cause sentence errors and difficult for elementary students to use. Therefore, it is best to use block-based language for program to operate robots for elementary students. Second, robot's body operated with the connection of software is appropriate for block assembly robot rather than fully built robot or semi-assembled robot for student to make robot oneself creatively. In order to fully understand the function of sensors, it is decided that robot can be composed to perform and show the result for sensor function separately. Third, instead of unitized robot fully installed with device such as sensor, LED, and etc. in body or control device, robot assembled with connecting the port with individualized devices by student oneself are judged appropriate to understand much more efficiently in functioning of robot or sensor. Fourth, main monitor of software to operate robot shows categorized block about robot operation. Each categorized blocks show parts name relate to operation and colors should make clear of separation. As a result of operation element of parts separately it can improve immediacy. Fifth, teachers who evaluated the Entry software for robot operation in elementary practical arts assessed that 'robot function and structure' unit achieved standard of accomplishment and formed well in learning and teaching efficiently.

Demand for precision optical system is increased due to the rapid development of aerospace, defense, and imaging fields. Research to produce high precision reflector mirror is being carried out. In particular, confocal off-axis reflecting optical system can be applied to various fields due to the advantage of being able to implement a short focal length and a large field of view. The axis of freeform reflector is asymmetrical, so ultra precision machining which is possible to accurately controls over three- axis is required for the reflector. Precision machining of free-form reflectors is more difficult than precision machining of symmetrical reflector. In this study, effect of mirror mounting structure on cutting characteristics was researched by finite element analysis(FEA) to set the reference plane using the machining and measurement of the freeform mirror. The mirror mounting has been divided into four types of squares, hexagons, octagons, and dodecagon. This study of FEA shows that there are not much difference in stress on the surface of the mirror for rotating and cutting forces. It was confirmed that deflection have great different over 5 times according to mounting structure. The analysis results are expected to be useful in the assembly part design and production to minimize the manufacturing tolerances of the freeform mirror.

ROPS is a structure installed to protect drivers from tractor rollover accidents and is being tested for certification under the OECD code. Because this test requires a lot of cost and time to develop the ROPS and to produce test model, the OECD is discussing the introduction of virtual test using finite element analysis. In this study, the results were compared by conducting a strength test and finite element analysis applied with the OECD code to use it as a basic data for standardization of ROPS virtual test methods. It was confirmed that the results of the analysis of the bolts and plates of the coupling part and the folding part were more close to the physical test results than the rigid elements and constraints at the point of coupling the tractor and ROPS.

This study was carried out to standardize the material properties of roll-over protective structure (ROPS) for agricultural tractor. The material properties which were obtained from stress-strain curve, a result of tensile test stress, were used to apply to the virtual test and varied from one production lot to the other and from one manufacturer to the other. And the finite element analysis was performed on the ROPS according to the OECD code. The results show that the load-displacement curves of virtual test were approximately equal to the actual test curves. The manufacturer or lot has been shown to have little effect on the properties of the material. Therefore, it is expected that the representative values that can be used in the finite element analysis can be determined by averaging the property values.

Welding sequence is the important influence factor of the temperature field and residual stress and deformation in welding structure, At present, determining the welding sequence is usually based on experience and test method. For complex structure it is very difficult to get the optimum welding sequence. This study is aiming to settle the problem of solving the optimum welding sequence of complex box welding structure. In our study, we take the welding deformation as objective function, and then, associate glowworm swarm optimization algorithm with thermal-mechanical coupling and nonlinear thermal elastoplastic finite element model to optimize numerical simulation, eventually the optimum welding sequence is determined. Optimization results demonstrate that the optimum welding sequence obtained by our method has small welding deformation and little change rate. At the same time, our method is faster, more accurate, more effective than the traditional experience or test method.

In this study, a finite element analysis approach is proposed to predict the fluid-structure interaction behavior of active materials for lithium-ion batteries (LIBs), which are mainly composed of graphite powder. The porous matrix of graphite powder saturated with fluid electrolyte is considered a representative volume element (RVE) model. Three different RVE models are proposed to consider the uncertainty of the powder shape and the porosity. P-wave modulus from RVE solutions are analyzed based on the microstructure and the interaction between the fluid and the graphite powder matrix. From the results, it is found that the large surface area of the active material results in low mechanical properties of LIB, which leads to poor structural durability when subjected to dynamic loads. The results obtained in this study provide useful information for predicting the mechanical safety of a battery pack.

In this study, a finite element analysis approach is proposed to predict the fluid-structure interaction behavior of active materials for lithium-ion batteries (LIBs), which are mainly composed of graphite powder. The porous matrix of graphite powder saturated with fluid electrolyte is considered a representative volume element (RVE) model. Three different RVE models are proposed to consider the uncertainty of the powder shape and the porosity. Pwave modulus from RVE solutions are analyzed based on the microstructure and the interaction between the fluid and the graphite powder matrix. From the results, it is found that the large surface area of the active material results in low mechanical properties of LIB, which leads to poor structural durability when subjected to dynamic loads. The results obtained in this study provide useful information for predicting the mechanical safety of a battery pack.

Accurate seismic analyses of large deformable moving structures are still unsolved problems in the field of earthquake engineering. In order to analyze these problems, the nonlinear finite element method formulated by the absolute nodal coordinate approach is noticed. Because, this formulation has several advantages over the standard procedures on mass matrix, elastic forces and damping forces in the case of large displacement problems. But, it has not been fully studied to build frame structure models by using beam elements in the absolute nodal coordinate formulation. In this paper, we propose the connecting method of the beam elements formulated by the absolute nodal coordinate. The coordinate transformation matrix of this element is introduced into the frame structure. This beam element has the characteristic that the mass matrix and bending stiffiness matrix are constant even if in the case of large displacement problems, and this characteristic is being kept after the transformation. In order to verify the proposed method, we show the numerical simulation results of frame structures for a vibration problem and a large displacement problem.

It can be said that rock mass properties are characterized not by a mean value but by values with variation due to its characteristic uncertainty. This characteristic is one of the most important parts for the design of underground structures, but yet to be fully examined. Stochastic finite element method (SFEM) has been developed in order to take the randomness of structural systems into account. Using SFEM, the response variability of structural system can be obtained and it leads probabilistic stability of structure to be analyzed. In this study, displacements response variability of circular opening with hydrostatic stress field are analyzed in terms of rock mass properties having a certain mean and a standard deviation using the SFEM. The analyzed response variability shows that the necessity of probabilistic stability analysis of underground structures using reliable mean value and standard deviation of deformation modulus.