Huntington씨 병이 의심되는 2례

이현섭,백성욱,김상욱 대한신경과학회 1988 대한신경과학회지 Vol.6 No.2

전해이온화 슬러리 CMP 에서 과산수소 함량 변화에 따른 전기화학적 특성 분석

이현섭,조예진,김용훈,남영현 대한기계학회 2022 대한기계학회 춘추학술대회 Vol.2022 No.5

매칭 모듈을 이용한 이동 객체와 VR 영상의 동기화

이현섭,유은재,김진덕,Lee, Hyoun-Sup,You, Eun-Jae,Kim, Jin-deog 한국정보통신학회 2017 한국정보통신학회논문지 Vol.21 No.7

최근 Virtual Reality(VR)와 Augmented Reality(AR)가 ICT분야에서 관심분야로 떠오르고 있다. 가상에서 실제와 같은 현실감을 느끼고 그 매력에 많은 사람들이 찾고 있다. 하지만 VR 이미지와 이동 객체의 움직임이 정확하게 들어맞지 않아 멀미를 느끼는 문제점도 발생하고 있다. 이와 같은 문제점을 해소할 수 있는 방안으로 VR 시스템의 어트랙션 적용이 있다. 본 논문에서는 VR 영상과 이동하는 객체의 움직임을 동기화하여 지연시간을 최소화할 수 있는 모듈을 제안한다. 제안하는 모듈은 VR 기기를 통하여 사용자가 바라보는 방향과 가속도 센서를 이용하여 이동 거리를 산출한다. 이 논문에서 제안하는 모듈은 어트랙션의 움직임이 고정된 경로를 따라 움직인다는 점을 주목하여 정확한 이동거리를 계산할 수 있을 것으로 사료된다. Recently, VR and AR are emerging as an area of interest in ICT. In virtual reality to feel like a real, many people are looking for them because of its charm. However, the motion of the VR image and the moving object are not synchronized exactly, and a problem of feeling nausea is also occurring. The problem should be solved by the application of Attraction in the VR system. In this paper, we propose a module that minimizes delay time by synchronizing movement of VR image and moving object. The proposed module calculates the moving distance using the direction and the acceleration sensor that the user views through the VR device. The module proposed in this paper will pay attention to the fact that the movement of the attraction moves along a fixed path, so that the accurate travel distance can be calculated.

Mathematical Modeling of Material Removal Rate in Roll- Type Linear CMP (Roll-CMP) Process: Effect of Polishing Pad

이현섭 한국정밀공학회 2016 International Journal of Precision Engineering and Vol.17 No.4

Recently, a roll-type linear chemical mechanical polishing (Roll-CMP) process was developed for fabricating large flexible substrates such as flexible printed circuit boards (FPCBs). The major difference between the Roll-CMP and the conventional CMP is the type of contact between the polishing pad and the substrate. Roll-CMP uses line contact for material removal of the Cu film on FPCBs. Many researchers have studied mathematical models to understand the conventional CMP process. In this paper, a mathematical model on the material removal rate (MRR) of Roll-CMP is proposed based on Hertzian contact theory and previously studied models on conventional CMP to understand the effect of the polishing pad. Two kinds of polishing pads were prepared to investigate their effect on the material removal of copper clad laminate (CCL). The increase in the average radius of pad asperities over the standard deviation of pad asperities increases MRR. The slurry loading capacity of the polishing pad impacts the MRR of Cu as well. The proposed model may offer a theoretical understanding for the Roll-CMP process.

압력도수터널 콘크리트 라이닝 구조 계산시 외수압 처리에 관한 연구

이현섭,이영준,서승우,황영철,Lee, Hyeon-Sub,Lee, Young-Joon,Seo, Seung-Woo,Hwang, Young-Chul 한국터널지하공간학회 2015 한국터널지하공간학회논문집 Vol.17 No.6

압력도수터널 콘크리트 라이닝 구조계산시 암반의 이완하중, 내수압, 외수압, 건조수축, 그라우팅압 등 다양한 하중조건을 고려하는데, 아직까지 국내에는 압력도수터널에 대한 콘크리트 라이닝 구조해석을 위한 설계기준 및 체계적인 매뉴얼이 없으므로 설계자에 따라 다르게 적용되고 있는 실정이다. 특히, 도수터널은 외수압을 저감시키기 위해 Weep Hole을 설치하는 경우도 있는데, Weep Hole 설치로 인해 많은 문제점이 야기될 수도 있으므로 Weep Hole을 설치하지 않을 시 외수압 처리에 대한 합리적인 접근 방법이 필요하다. 따라서, 본 논문에서는 압력도수터널 콘크리트 라이닝 구조 계산시 외수압 처리에 대해 기존 설계사례 및 문헌 등을 분석하여 합리적이고 적절한 설계개념에 대하여 서술하였다. When the structural analysis is performed for the concrete lining of the water pressure tunnel, many parameters are considered such as relaxed ground loads, internal water pressure, external water pressure, the shrinkage of the concrete lining, grouting pressure, etc. But, there are no standards and manuals for the structural analysis for the concrete lining of the water pressure tunnel. Above all, the external water pressure has an much effect on the stability of tunnel. So, in case that permeability of ground is large, the external water pressure should be decreased by installation of weep hole, or reinforced ground by ground improvement grouting should be pressed by the external water pressure instead. But, when weep hole is installed to reduce the external water pressure, the many problems may me occurred. Thus, reasonable approach for treatment of the external water pressure is necessary if weep hole is not installed. Therefore, the purpose of this study is to analyze design cases and studies for treatment of the external water pressure in performing structural analysis for the concrete lining of the water pressure tunnel, and to find reasonable method for tunnel lining modeling which is the treatment of the external water pressure according to permeability of ground and consequently the design of ground improvement grouting.

Temperature Distribution in Polishing Pad during CMP Process: Effect of Retaining Ring

이현섭,구영창,정해도 한국정밀공학회 2012 International Journal of Precision Engineering and Vol.13 No.1

Heat generation is inevitable during the chemical mechanical planarization (CMP) process because the mechanical and chemical removal of material is carried out by using abrasives and chemicals in the CMP slurry. In this paper, results obtained from experiments performed on a membrane-type carrier having a retaining ring were used to study the temperature distribution in a polishing pad during the CMP process. To understand and predict the distribution of temperature rise, a kinematical analysis of the temperature distribution was performed by considering the frictional characteristics of the process. The results of this study can be used to predict the temperature distribution in a polishing pad, and such predictions can help in developing a more effective CMP process.

화학기계적 연마(CMP) 공정에서의 트라이볼로지 연구 동향

이현섭 한국트라이볼로지학회 2018 한국트라이볼로지학회지 (Tribol. Lubr.) Vol.34 No.3

Chemical mechanical polishing (CMP) is a hybrid processing method in which the surface of a wafer is planarized by chemical and mechanical material removal. Since mechanical material removal in CMP is caused by the rolling or sliding of abrasive particles, interfacial friction during processing greatly influences the CMP results. In this paper, the trend of tribology research on CMP process is discussed. First, various friction force monitoring methods are introduced, and three elements in the CMP tribo-system are defined based on the material removal mechanism of the CMP process. Tribological studies on the CMP process include studies of interfacial friction due to changes in consumables such as slurry and polishing pad, modeling of material removal rate using contact mechanics, and stick-slip friction and scratches. The real area of contact (RCA) between the polishing pad and wafer also has a significant influence on the polishing result in the CMP process, and many researchers have studied RCA control and prediction. Despite the fact that the CMP process is a hybrid process using chemical reactions and mechanical material removal, tribological studies to date have yet to clarify the effects of chemical reactions on interfacial friction. In addition, it is necessary to clarify the relationship between the interface friction phenomenon and physical surface defects in CMP, and the cause of their occurrence.

Evaluation of environmental impacts during chemical mechanical polishing (CMP) for sustainable manufacturing

이현섭,Sunjoon Park,정해도 대한기계학회 2013 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.27 No.2

Reducing energy consumption has become a critical issue in manufacturing. The semiconductor industry in particular is confronted with environmental regulations on pollution associated with electric energy, chemical, and ultrapure water (UPW) consumptions. This paper presents the results of an evaluation of the environmental impacts during chemical mechanical polishing (CMP), a key process for planarization of dielectrics and metal films in ultra-large-scale integrated circuits. The steps in the CMP process are idling, conditioning, wetting, wafer loading/unloading, head dropping, polishing, and rinsing. The electric energy, CMP slurry, and UPW consumptions associated with the process and their impacts on global warming are evaluated from an environmental standpoint. The estimates of electric energy, slurry, and UPW consumptions as well as the associated greenhouse gas emissions presented in this paper will provide a technical aid for reducing the environmental burden associated with electricity consumption during the CMP process.

Mechanical Aspects of the Chemical Mechanical Polishing Process: A Review

이현섭,이다솔,정해도 한국정밀공학회 2016 International Journal of Precision Engineering and Vol.17 No.4

Chemical mechanical polishing (CMP) is an essential semiconductor manufacturing process because of its local and global planarization ability in fabricating highly integrated devices. The CMP process uses both chemical reaction and mechanical polishing simultaneously. The combination of chemical reaction and mechanical removal in CMP is so complex that understanding the material removal mechanism has been a challenge for researchers and engineers. The chemical reaction mechanism is determined by the chemical composition of the CMP slurry and the material property of the target material. However, the mechanical action is a complex result of various mechanical factors of the process parameters and consumables. The mechanical material removal is a cornerstone of understanding and predicting CMP results. This review focuses on the mechanical aspects in CMP in terms of the process parameters and consumables of the CMP process that directly influence the material removal characteristics.

특허 데이터 및 토픽 모델링을 활용한 CCUS 기술동향 분석

이현섭,서원철,이운식 대한산업공학회 2022 대한산업공학회 춘계학술대회논문집 Vol.2022 No.6