• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2002년도 하계종합학술대회 논문집(3)
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• pp.131-134
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• 2002

As the increased use of computer, wired/wireless/mobile Internet, security in using Internet becomes a more important problem. Thus, biometric technology using physical and behavior characteristics of a person is hot issue. Many different types of biometric technologies of a person such as fingerprint, face, iris, vein, DNA, brain wave, palm, voice, dynamic signature, etc. had already been studied but remained unsuccessful because they do not meet social demands. However, recently many of these technologies have been actively revived and researchers have developed new products on various commercial fields. Dynamic signature verification technology is to verify the signer by calculating his writing manner, speed, angle, and the number of strokes, order, the down/up/movement of pen when the signer input his signature with an electronic pen for his authentication. Then signature verification system collects mentioned above various feature information and compares it with the original one and simultaneously analyzes to decide whether signature is forgery or true. The prospect of signature verification technology is very promising and its use will be wide spread in terms of economy, security, practicality, stability and convenience.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2002년도 추계학술대회 논문집
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• pp.867-870
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• 2002

In high-speed optical disk drive, the excitation caused by rotation of a mass-unbalanced disk is a major source of vibration. The vibration can be a disturbance to the servo system, which is sufficient to cause severe failures in the reading and writing process. The vibration also causes users to feel unpleasantness. The vibration reduction is therefore essential for the reliable operation of optical disk drive. One of the approaches to reduce the vibration is a dynamic vibration absorber (DVA). In this paper, we analyze the dynamic behavior of $DVD\pmRW$ combo drive system with DVA through 12_dof rigid multi-body dynamic model. The effective location and the optimal frequency ratio are obtained from the analysis.

• 한국소음진동공학회논문집
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• 제16권5호
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• pp.529-536
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• 2006

In high-speed optical disk drive, the excitation caused by rotation of a mass-unbalanced disk is a major source of vibration. The vibration can be a disturbance to the servo system, which is sufficient to cause severe failures in the reading and writing process. The vibration also causes users to feel unpleasantness. The vibration reduction is therefore essential for the reliable operation of optical disk drive. One of the approaches to reduce the vibration is a dynamic vibration absorber(DVA). In this paper, we analyze the dynamic behavior of $DVD{\pm}RW$ combo drive system with DVA through 12-dof rigid multi-body dynamic model. The effective location and the optimal frequency ratio for the DVA are obtained from the analysis. The DVA are fabricated based on the analysis and its usefulness is confirmed.

• 한국세라믹학회지
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• 제54권6호
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• pp.470-477
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• 2017

Ceramic processing to fabricate 3D complex ceramic structures is crucial for structural, energy, environmental, and biomedical applications. A unique process is ceramic stereolithography, which builds ceramic green objects from CAD files from many thin liquid layers of powder in monomer, which are solidified by polymerization with a UV laser, thereby "writing" the design for each slice. This approach directly writes layers in liquid ceramic suspension and allows one to fabricate ceramic parts and products having more accurate, complex geometries and smooth surfaces. In this paper, both UV curable materials and processes are presented. We focus on the basic material principles associated with free radical polymerization and rheological behavior, cure depth and broadening of cured lines, scattering at ceramic interface and their corresponding simulation. The immediate potentials for ceramic AM to change industry fabrication are also highlighted.

• 아동학회지
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• 제26권4호
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• pp.173-188
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• 2005

To examine relationships between learning-related social skills(LRSS) and literacy development a sample of 167 children aged 5-6 years were selected from 3 preschools in Seoul. Instruments for measuring LRSS were the cooperation, assertion, and self-control scales of the Social Skills Rating System (Gresham & Elliott, 1990) and the mastery behaviors scales of the Child Behavior Rating Scale (Bronson, et al. 1990). Literacy development was measured by the Concepts about Print(Woon, 1999), the Learning Readiness Scale(Korean Educational Development Institution 1998), and the Writing Development Scale(Lee, 1997). Teachers rated children's LRSS. Data were analyzed by mean, standard deviation, t-test, bivariate correlation, and regression analysis. LRSS correlated with children's literacy development. Mastery behaviors were the best predictor of literacy development.

• Bulletin of the Korean Chemical Society
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• 제22권3호
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• pp.271-275
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• 2001

We investigated H-type molecular aggregation in a simply spin-coated amorphous homopolymer film of polymethacrylate containing push-pull azobenzene moieties. It was found that the aggregate formation was strongly influenced by thermal treatment an d that the aggregate created in the polymer film could be easily disrupted by irradiation of a linearly polarized light. In the first writing cycle of aggregated polymer film, photo-induced birefringence showed a steep increase to the highest value followed by a gradual decrease to the certain asymptotic value under longer irradiation of a linearly polarized light. This unique behavior could be attributed to the cooperative motion and the disruption of the aggregated molecules under continuous irradiation of light.

• Structural Engineering and Mechanics
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• 제87권6호
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• pp.601-614
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• 2023

In this study, the uniaxial ratcheting effect of Z2CND18.12N austenitic stainless steel at room and elevated temperatures is firstly simulated based on the Ahmadzadeh-Varvani hardening rule (A-V model), which is embedded into the finite element software ABAQUS by writing the user material subroutine UMAT. The results show that the predicted results of A-V model are lower than the experimental data, and the A-V model is difficult to control ratcheting strain rate. In order to improve the predictive ability of the A-V model, the parameter γ2 of the A-V model is modified using the isotropic hardening criterion, and the extended A-V model is proposed. Comparing the predicted results of the above two models with the experimental data, it is shown that the prediction results of the extended A-V model are in good agreement with the experimental data.

• 한국직업건강간호학회지
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• 제10권1호
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• pp.74-92
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• 2001

This study was carried out to investigate the types of health documents for nurses, the content of informations in the documents, and writing behaviors of occupational health nurses. Health documents were collected from 7 nurses who were working in 7 group occupational health agencies (GOHA) located at Seoul and Inchon area in Korea. The collected health documents written in January to June 1999 were analyzed, and revealed the following results. 1) The occupational health nurses were using 9 to 18 different types of health documents. The contents of the documents were considered quite similar to each other with slightly different headings and items to record. Among different types of health documents. Health Management Card for Workplace', Nursing performance sheet and Workplace environmental checklist were in common among nurses and were used for content analysis. 2) The 'Health Management Card for Workplace' was the only formal sheet of small-scale-enterprises (SSE) for health management, in which health and safety related information was recorded. The information on nursing services were recorded on the Nursing performance sheet, which has slightly different names on each type with similar contents. The Workplace environment checklist was for the information on general work environment management and mainly status of workplace hygiene. This checklist is to be used by or with nurses among the 3 types health professional team such as doctor, hygienist, and nurse, but it seemed not being used frequently by nurses. 3) Analysis on recording tendencies of nurses revealed that the writing styles of occupational health nurses were associated with 'memo' using a few number of words and short sentences. The amount of information by this kind of recording style was considered not enough for health management situation. The possible reasons for nurses to use this writing style might be insufficient time for recording and improper designed format of health documents. Because nurses working in SSE spend more time on the roads to visit workplaces, nurses may not found enough time for recording properly within their working time. In addition, the health records were designed to focus on the frequency of nurse's performance in certain types of work rather than on the method they used to deal with health problems. In conclusion, this study suggests that some steps are necessary to develop health documents and recording system which is appropriate to occupational health nurses. The educational need for nurses on appropriate recording behavior is also recommended.

• 대한소아치과학회지
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• 제44권4호
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• pp.427-436
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• 2017

본 연구의 목적은 국내 실정에 맞는 행동유도법에 대한 보호자의 인식도를 조사하여 어린이 환자와 보호자, 그리고 치과 의사간의 긍정적인 관계를 설정하는데 기초 자료를 제공하는 것이다. 117명의 보호자에게 소아치과에서 사용되는 행동유도법에 대해 구두로 설명한 후 설문지를 작성하게 하였다. 설문지에 포함된 행동유도법은 다음과 같다: 말-시범-시행법, 음성조절법, 기구에 의한 보호안정법, 의료진에 의한 보호안정법, 아산화질소-산소 흡입진정법, 의식하 진정법, 전신마취법. 106명의 보호자의 설문지가 분석을 위해 채택되었다. 말-시범-행동법에 대한 인식도가 가장 높았다. 그 뒤로 음성조절법, 의료진에 의한 보호안정법, 아산화질소-산소 흡입진정법, 기구에 의한 보호안정법, 의식하 진정법, 전신마취법 순으로 낮아졌다. 보호자의 연령, 성별, 환자의 나이, 환자의 성별, 환자의 치과 경험 유무, 치과 방문의 종류, 의료진의 직위는 보호자의 행동유도법에 대한 인식에 영향을 미치지 않았다. 보호자들은 의사소통을 통한 행동유도법(말-시범-시행법, 음성조절법)을 가장 긍정적으로 생각하며, 전신마취법에 의한 행동유도법을 가장 부정적으로 생각하는 것으로 나타났다.

• 컴퓨터교육학회논문지
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• 제23권2호
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• pp.53-64
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• 2020

동영상 강의 중심의 온라인 학습 형태가 보편화 되고 지속적으로 증가됨에 따라 다양한 교육방법을 적용한 동영상 기반 학습 환경도 학습 효과성을 높이기 위해 변화, 발전하고 있다. 온라인 학습 환경에서의 교육 효과성 측정을 위해 학습자 로그 데이터가 대두되었으며, 학습자 맞춤형 학습 처방을 위해 로그 데이터의 다양한 분석 방법이 중요하다. 이를 위해 본 연구에서는 동영상 기반 학습 환경에서의 학습자 행동 데이터 분석, 머신러닝 기법에 따른 학업성취 예측을 실험을 통해 분석하였다. 분석 결과 각 모델에서 공통적으로 동영상 탐색과 코멘트 작성과 같은 상호작용 행동, 학습자 주도적 학습 행동이 학업성취를 예측하였다. 연구 결과를 토대로 동영상 학습 환경 설계에 있어 시사점을 제공하였다.