• Transactions of Materials Processing
• /
• v.30 no.6
• /
• pp.275-283
• /
• 2021

A parametric study was conducted on the effects of five fundamental design parameters on springback, including die clearance, step height, step width, punch radius, and taper relief in an L-bending process, controlled by the compression force. The experiment was also conducted to verify the usefulness of the parametric study procedure for process design, as well as the finite element predictions. The elastoplastic finite element method was utilized. The L-bending process of the york product, which is a key part of the breaker mechanism, was employed. The deformation of the material was assumed to be due to plane strain. Five samples of each design parameter were selected based on experiences in terms of process design. The finite element predictions were analyzed in detail to show a shortcut towards the process design improvement which can replace the traditional process design procedure relying on trial-and-errors. The improved process design was verified to meet all the requirements and the predictions and experiments were in good agreement.

• Transactions of Materials Processing
• /
• v.28 no.3
• /
• pp.115-122
• /
• 2019

In this paper, finite element analysis of an automatic five-stage precision cold forging process of a yoke, a steering part of a passenger's car, is conducted with emphasis on spring back analysis at the yoke-forming stage and its experimental verification is subsequently made. An elastoplastic finite element method with MINI-element technique employed for the analysis of the entire process is explained. There is emphasis that the thin film of material formed between the punch and die in the stage may result to some errors especially in elastoplastic finite element analysis of spring back due to frequent remeshing. The numerical robustness of the spring back analysis in regards to remeshing is hence shown first through investigation into its effect on the predicted spring back. Experimental measurement of displacement due to spring back is carried out for comparison with the predicted results, and they are in a qualitative agreement with each other.

• Journal of Periodontal and Implant Science
• /
• v.51 no.5
• /
• pp.364-372
• /
• 2021

Purpose: This study aimed to clinically evaluate the efficacy of vestibuloplasty around lower molar implants using 3 different modalities: apically positioned flap alone (APF), APF with a free gingival graft (FGG), and APF with modified periosteal fenestration (mPF). Methods: Three different vestibuloplasty procedures during second-stage implant surgery were performed at the mandibular molar area in 61 patients with a shallow vestibule and insufficient keratinized tissue (KT). The clinical measurements of KT width were recorded at baseline, immediately after surgery (T0), 6 months after surgery (T6), and 12 months after surgery (T12). Soft tissue esthetic scores were measured. Results: An additional KT width gain from baseline to T12 of approximately 2 mm was obtained with FGG and mPF compared to that with APF. Shrinkage of the re-established tissue was lower with mPF and FGG than with APF, whereas the esthetic profile was better with APF and mPF than with FGG. Conclusions: Within the limitations of this study, mPF showed potential as a promising approach for vestibuloplasty around the lower molar implants compared to the traditional APF and FGG.

• Transactions of Materials Processing
• /
• v.30 no.2
• /
• pp.83-90
• /
• 2021

In this paper, a parametric study on the influence of friction between materials on pull force in single clinching is conducted using an axisymmetric elasto-plastic finite element method and law of Coulomb friction. An appropriate finite element analysis model is given, which minimizes the effect of the material model and numerical factors including the number of quadrilateral finite elements and blank radius. It is emphasized that the elasto-plastic material model should be employed because the elastic deformation of the internal region is affected more by the pull force. It has been shown that the pull force increases as friction coefficient increases and that the optimized friction coefficient is around 0.4, which is qualitatively comparable with its theoretical value. When the friction coefficient reaches 0.5 in the example studied, the neck fracture is predicted.

• Proceedings of the Korean Society of Computer Information Conference
• /
• 2023.07a
• /
• pp.481-483
• /
• 2023

본 논문에서는 다중 카메라환경에서의 안면인식 기반 영유아 활동 사진 자동 생성 시스템을 개발했다. 개발한 시스템은 어린이집에서 알림장 작성을 위한 촬영하는 동안 보육에 부주의하여 안전사고가 발생하는 것을 방지 할 수 있다. 시스템은 이동식 수집기와 분류 서버로 나뉘어 작동하게 된다. 이동식 수집기는 Raspberry Pi를 이용하였고 초당 1장 내외의 사진을 촬영하여 SAMBA를 사용 공유폴더에 저장한다. 분류 서버에서는 YOLOv5를 사용해 안면을 인식해 분류한다. OpenCV와 TensorFlow-Keras를 통해 분류된 사진에서의 표정을 파악하여 부모에게 전송할 웃는사진만을 분류하여 남겨둔다. 이외의 사진은 /dev/null로 이동하여 삭제된다.

• Proceedings of the Korea Information Processing Society Conference
• /
• 2023.11a
• /
• pp.662-664
• /
• 2023

해양 식물플랑크톤의 성장은 유해적인 적조를 유발할 수 있으며, 이는 여러 국가의 생태계에 피해를 주는 상황이다. 적조를 모니터링하는 것은 식물플랑크톤 미생물의 증가를 예방하고 통제하기 위해 중요하다. 그러나 현재의 적조 모니터링 기술은 날씨, 시간 제약 및 실시간 모니터링에 대한 어려움으로 인해 측정 정확도에 영향을 미치는 한계가 있다. 본 연구는 특히 적조 발생을 감지하기 위한 목적으로 개발된 자동 실시간 모니터링 시스템의 성공적인 개발을 보여준다. 개발한 시스템은 음향 반사파 데이터 처리를 통해 합성곱 신경망(Convolutional neural networks, CNN)을 활용하여 식물플랑크톤 농도를 정확하게 구별할 수 있다. 특히, 이 CNN 모델은 음향 신호의 변환된 주파수 스펙트럼과 Cochlodinium polykrikoides (C. polykrikoides)의 농도 간의 상관 관계를 수립하는 데 뛰어난 효과를 나타냈다. 이 CNN 은 C. polykrikoides 를 감지하는 데 0.90 의 정확도를 보여준다. 이러한 모니터링과 CNN 분류의 활용은 실시간 측정의 중요한 잠재력을 보여주며, 추가적인 절차가 필요 없는 자동 모니터링 시스템을 구축할 수 있을 것으로 예상된다.

• Asia pacific journal of information systems
• /
• v.29 no.3
• /
• pp.359-381
• /
• 2019

Social networking services (SNSs) have become important and popular tools for not only presenting self-image but also sharing travel information. This study adopted self-image expressions to understand tourists' intentions to share travel information and behavioral changes in SNSs. To enhance understanding tourists' intention and behavior, the current study suggests a research model based on motivations for self-image expression (i.e., creativity, altruism and social relationship). This current study empirically resulted in the importance of users' creativity, altruism and social relationship in SNS, which leads to the intention and behavioral changes to share travel information. In addition, altruism moderated the negative effect of creativity on self-image expression as well as the positive effect of the social relationship on self-image expression. Based on the result of this study, the current study bears some implications in a theoretical and practical context.

• Journal of Digital Convergence
• /
• v.12 no.9
• /
• pp.1-7
• /
• 2014

Entrepreneurship and entrepreneurship courses, including my recent absence undergraduate entrepreneurship-friendly system is activated, the spread of technology startups to be scanning my college. However, the college is successful technology startups to take place in order to be solved many problems still exist. In this paper, we have a hard job and continuing high unemployment and social environment college students majoring in IT technology to enable the establishment of the control action for the establishment and analysis of influencing factors. In particular, IT college students majoring in technology startups will affect students' technical skills and characteristics of entrepreneurs and Entrepreneur's motive, entrepreneurship environment outside the extraction and evaluation items such as IT skills to analyze the impact of entrepreneurship. In analysis result, IT major career college students interested in entrepreneurship as an alternative to the higher technology, technical skills and characteristics of entrepreneurs and start-motivated alternative to independence and had an impact on employment. In addition, the university was founded in tech startups according to the environment of entrepreneurship education has a lot of outside influence.

• Journal of the Korea Society of Computer and Information
• /
• v.19 no.9
• /
• pp.45-53
• /
• 2014

This paper suggests methods to chronicle and track the history of dialogues exchanged among characters to prevent logical errors of a story. As for stories that are long with many characters, especially in full-length novels and co-written stories, cognitive burden is imposed on a writer. If the writer has confused understanding of a character, then a logical error would enter the story. This would compromise completeness and integrity of writing. Against the backdrop, this paper shows how dialogues among characters are chronicled and tracked by using the aforementioned tracking methods through design of a writer support system that relieves a writer's cognitive burden while supporting the writing and through an analysis of existing novels. In addition, we showed the accuracy results of average 68.5% through the performance evaluation of the query used in the dialogue history tracking.

• Journal of the Institute of Electronics Engineers of Korea SD
• /
• v.44 no.11
• /
• pp.89-94
• /
• 2007

For successful implementation of multi-standard transmitter, reconfigurable architecture and component design are essential. This paper presents a reconfigurable CMOS power amplifier designed CMOS 0.25 um process. Designed power amplifier can be operated at 0.9, 1.2, 1.75, and 1.85 GHz. Also, it can be used at 2.4 GHz by using bonding wire inductor. The interstage matching network is composed of two inductors and four switches, and operation frequency can be varied by controlling switches. Proposed power amplifier can be used as a power amplifier in low power applications such as ZigBee or Bluetooth application and used as a driver amplifier in high power application such as CDMA application. Designed power amplifier has 18.2 dB gain and 10.3 dBm output power at 0.9 GHz. Also, it represented 10.3 (18.1) dB gain and 5.2 (10) dBm output power at 1.75 (2.4) GHz.