• 한국학교수학회논문집
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• 제25권4호
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• pp.423-446
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• 2022

본 연구는 덧셈 뺄셈 연산에서 보이는 수학적 전략을 한국과 미국의 예비 초등교사가 어떻게 분석하는지 비교 분석한다. 한국의 예비교사 26명과 미국의 예비교사 20명이 본 연구에 참여하였으며, 제시된 덧셈 뺄셈 연산에서 어떠한 수학적 오류가 있는지 서술하게 하였다. 수합된 46명의 예비교사의 기록은 연구의 주요 데이터로 근거 이론에 기반을 두어 오픈 코딩과 귀납 코딩하고, 통계 처리하여 혼합 연구를 진행하였다. 그 결과, 덧셈 연산에 대한 오류와 전략 분석에서 양국의 예비교사의 응답 양상은 유사하였으나, 뺄셈 연산에서는 차이가 있음을 확인하였다. 또한, 학생의 풀이 전략이 다단계로 구성이 되어 있거나 전형적이지 않을 때, 양국의 예비교사가 이를 분석하는데 어려워함을 확인하였다. 국제 비교 연구 결과를 바탕으로 양국의 예비교사 교육에 공통적인 시사점을 제공하고, 각국의 예비교사 교육에 새로운 방향을 논하였다.

• 한국정보통신학회논문지
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• 제9권7호
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• pp.1419-1424
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• 2005

본 논문에서는 통신 채널의 오류로 인하여 통신 단말간에 서로 송수신되는 정보중에 임의의 비트가 삭제되거나 추가되어 암호 알고리즘을 사용하여 통신이 불가능해지는 경우, 이를 극복하기 위한 기법으로 Statistical CFB 방식의 암호 알고리즘을 제안한다. 먼저, 비트 삽입 또는 비트 삭제 발생 시 오류 전파의 영향을 수학적으로 모델링하여 이론적인 Statistical CFB 암호 알고리즘의 성능을 분석한다. 이 경우, Statistical CFB 방식의 성능을 결정하는 요소인 농기 패턴의 길이와 피프백되는 키의 길이를 변화해가며 분석하도록 한다. 또한 이론적인 분석과 함께 실제로 특정 길이의 동기 패턴과 피드백되는 키를 선택한 후, Statistical CFB 방식을 적용한 암호 알고리즘을 사용하여 성능을 분석하였다. 이를 이론적인 분석 결과와 비교하여 제안된 암호 알고리즘의 타당성을 검증한다.

• 한국정밀공학회지
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• 제20권2호
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• pp.40-49
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• 2003

Ferrule is widely used as fiber optic connecters. In fiber-optic communications. the shape accuracy such as coaxiality and cylindricity of ferrule affects insertion loss. When coaxial grinding of ferrule supported by two pin. pin alignment and chucking accuracy are very important. In this research, the kinematic behavior of the ferrule centers are investigated in the case where the ferrule is chucked with the cone-shaped center pins and bail centers, With homogeneous coordinate transformation and numerical analysis, the obtained results are as follows: In the case of cone-type center, the alignment errors between center pins alone do not affect the rotation accuracy of ferrule. The alignment errors between center holes cause sinusoidal displacement of ferrule. And the maximum displacement of ferrule centers is proportional to the center pin angle. In the case of ball-type center, the displacements of ferrule centers has similar pattern as cone-type center, and the alignment errors art proportional to ball diameters.

• 영어어문교육
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• 제12권4호
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• pp.31-68
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• 2006

The present research investigates the acquisition of the English locative alternation by Korean EFL learners, which poses a learnability paradox, taking Pinker's framework of learnability theory as its basis. It addresses two questions (1) how lexical knowledge is represented initially and at different levels of interlanguage development and (2) what kinds of difficulty Korean learners find in the acquisition of English locative verbs and their constructions. Three groups of learners at different proficiency levels with a control group of English native speakers are examined by two instruments: elicited production task and grammaticality judgment task. According to different levels of proficiency, the learners exhibit gradual sensitivity to a change-of-state meaning and obtain complete perception of the meanings of locative verbs (manner-of-motion and change-of-state) and their constructions. Overgeneralization errors are observed in their performance. The errors are due to misinterpretations of particular lexical items in conjunction with the universal linking rules. More fundamental cause of difficulty is accounted for by partial use of learning mechanisms, caused by insufficient L2 input.

• 한국기계가공학회지
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• 제6권4호
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• pp.8-14
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• 2007

Recently, the variation of industry has been changed faster and faster than before. It is using Rapid Prototyping Method to cope with fast change. This technology used to make a prototype, master pattern of manufactured product by vacuum casting, and so on. But this method has errors by contraction as a necessity. this error has been caused because the shape of prototype is smaller than CAD data. So we must solve the problem about precision of product. Therefore in this study, we will reduce the errors like contraction of material by manufacturing of rapid prototype product. Through these courses, we will enhance a precision of product.

• 대한전기학회논문지:시스템및제어부문D
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• 제51권10호
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• pp.453-459
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• 2002

This paper proposes an improved algorithm of the daily peak load forecasting for Korean Thanksgiving Day and the Lunar New Year's day. So far, many studies on the short-term load forecasting have been made to improve the accuracy of the load forecasting. However, the large errors of the load forecasting occur i case of Korean Thanksgiving Day and the Lunar New Year's Day. In order to reduce the errors of the load forecasting, the fuzzy linear regression method is introduced and a good selection method of the past load pattern is presented. Test results show that the proposed algorithm improves the accuracy of the load forecasting.

• 대한전기학회논문지
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• 제35권11호
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• pp.487-494
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• 1986

This paper is concerned with the techniques of error check and reduction of state diagram using logic programming. Error check program aims to check not only syntax errors but also semantic errors. And reduction program optimizes the state diagram by finding the redundant equivalence states and removing those from the set of states. The input of both program is state diagram represented as state table form. The output of error check program is error comment. The output of reduction program is equivalence reduced state table. Both programs are implemented using prolog. Prolog has very powerful pattern matching, and its automatic back-tracking capabilities facilitate easy-to-write error check and reduction programs.

• ETRI Journal
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• 제24권3호
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• pp.197-204
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• 2002

This paper presents the results of the numerical simulation of a multibeam active phased array antenna for a High Altitude Platform Station (HAPS). The simulation takes into account the random errors caused by the non-identity of the array elements and the inaccuracy of the antenna calibration. The results of our statistical simulation show that the strict requirements on the sidelobe envelope for HAPSs can be met when the amplitude and phase distribution errors are minor, a condition which may be achieved by using digital beamforming.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2003년도 신호처리소사이어티 추계학술대회 논문집
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• pp.187-190
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• 2003

In this paper, we propose an extrinsic calibration method for a multi-view camera to get an optimal pose in 3D space. Conventional calibration algorithms do not guarantee the calibration accuracy at a mid/long distance because pixel errors increase as the distance between camera and pattern goes far. To compensate for the calibration errors, firstly, we apply the Tsai's algorithm to each lens so that we obtain initial extrinsic parameters Then, we estimate extrinsic parameters by using distance vectors obtained from structural cues of a multi-view camera. After we get the estimated extrinsic parameters of each lens, we carry out a non-linear optimization using the relationship between camera coordinate and world coordinate iteratively. The optimal camera parameters can be used in generating 3D panoramic virtual environment and supporting AR applications.

• 한국정밀공학회지
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• 제22권5호
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• pp.80-86
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• 2005

Optical performance evaluation results and an interference fringe pattern analysis of alignment errors for an optical head of a near-field receding (NFR) system are presented. The focusing unit is an optical head of a NFR system and is composed of a solid immersion lens (SIL) and an objective lens (OL). Generally, the size of the focusing unit is smaller than that of the conventional optical recording head. Hence there are difficulties to assemble the small focusing unit precisely. We composed an evaluation system with an interferometer and evaluated some focusing unit samples aligned and assembled by manual and present the obtained results. Using the conventional optical tool, Code V, a tolerance analysis of the alignment error between the SIL and the objective lens and an interference pattern analysis for the assembly error are executed. Then, through an analysis of the simulation results, the conceptual auto-alignment methodology using a neural network approach is considered.