• 대한전자공학회논문지SD
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• 제47권3호
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• pp.18-27
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• 2010

본 논문에서는 offset self-calibration 기법을 적용한 7-bit 1GSPS folding-interpolation A/D 변환기를 제안한다. 제안하는 A/D 변환기는 folding rate 2, interpolation rate 8의 1+6 구조로 고속 동작에 적합하게 설계되었다. 또한 offset self-calibration 회로를 설계하여 공정 mismatch, 기생 저항, 기생 캐패시턴스 등에 의한 offset-voltage의 변화를 감소시켜 A/D 변환기의 성능 특성을 향상 시켰다. 제안하는 A/D 변환기는 1.2V 65nm 1-poly 6-metal CMOS 공정을 사용하여 설계 되었으며 유효 칩 면적은 $0.87mm^2$, 1.2V 전원전압에서 약 110mW의 전력소모를 나타내었다. 측정 결과 샘플링 주파수 800MHz, 입력 주파수 250MHz에서 39.1dB의 SNDR 특성을 보여주었으며, offset self-calibration 회로를 사용 하지 않은 A/D 변환기에 비해 SNDR이 약 3 dB 향상되었다.

• 대한전자공학회논문지SD
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• 제48권4호
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• pp.14-23
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• 2011

본 논문에서는 자체보정 벡터 발생기(Self-Calibrated Vector Generator)를 이용한 7-bit 2GSPS folding/interpolation A/D Converter (ADC)를 제안한다. 제안하는 ADC는 2GSPS 의 고속 변환에 적합한 상위 2-bit, 하위 5-bit 인 분할구조로 설계 되었으며, 각각의 folding/interpolation rate는 4와 8로 설정되었다. 최대 1GHz의 높은 입력신호를 처리하기 위해 cascade 구조의 preprocessing block을 적용하였으며, 전압 구동 방식 interpolation 기법을 적용하여 기준전압 생성 시 발생하는 추가적인 전력소모를 최소화하였다. 또한, 새로운 개념의 자체보정 벡터 발생기를 이용하여 device mismatch, 기생 저항 및 커패시턴스 등에 의한 offset error를 최소화하였다. 제안하는 ADC는 1.2V 0.13um 1-poly 7-metal CMOS 공정을 사용하여 설계 되었으며 calibration 회로를 포함한 유효 칩 면적은 2.5$mm^2$ 이다. 측정 결과 입력 주파수 9MHz, sampling 주파수 2GHz에서 39.49dB의 SNDR 특성을 보이며, calibration 회로의 작동결과 약 3dB 정도의 SNDR의 상승을 확인하였다.

• JSTS:Journal of Semiconductor Technology and Science
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• 제13권5호
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• pp.473-481
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• 2013

A fractional folding analog-to-digital converter (ADC) with a novel arithmetic digital encoding technique is discussed. In order to reduce the asymmetry errors of the boundary conditions for the conventional folding ADC, a structure using an odd number of folding blocks and fractional folding rate is proposed. To implement the fractional technique, a new arithmetic digital encoding technique composed of a memory and an adder is described. Further, the coding errors generated by device mismatching and other external factors are minimized, since an iterating offset self-calibration technique is adopted with a digital error correction logic. A prototype 8-bit 1GS/s ADC has been fabricated using an 1.2V 0.13 um 1-poly 6-metal CMOS process. The effective chip area is $2.1mm^2$(ADC core : $1.4mm^2$, calibration engine : $0.7mm^2$), and the power consumption is 88 mW. The measured SNDR is 46.22 dB at the conversion rate of 1 GS/s. Both values of INL and DNL are within 1 LSB.

• 전자공학회논문지
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• 제50권1호
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• pp.137-147
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• 2013

본 논문에서는 폴딩 구조에 저항열 인터폴레이션 기법을 적용한 1.2V 8b 1GS/s CMOS folding-interpolation A/D 변환기(ADC)에 대해 논한다. 기존 폴딩 ADC가 갖는 경계조건 비대칭 오차를 최소화하기 위해 홀수개의 폴딩 블록과 프랙셔널 폴딩 비율(fractional folding rate)을 사용하는 구조를 제안한다. 또한, 프랙셔널 폴딩기법을 구현하기 위해 덧셈기를 사용하는 새로운 디지털 인코딩기법도 제안한다. 그리고 iterating offset self-calibration 기법과 디지털 오차 보정 회로를 적용하여 소자 부정합과 외부 요인에 의한 노이즈 발생을 최소화하였다. 제안하는 A/D 변환기는 1.2V 0.13um 1-poly 6-metal CMOS 공정을 사용하여 설계 되었으며 $2.1mm^2$ 유효 칩 면적과(A/D 변환기 core : $1.4mm^2$, calibration engine : $0.7mm^2$), 350mW의 전력 소모를 나타내었다. 측정결과 변환속도 1GS/s에서 SNDR 46.22dB의 특성을 나타내었다. INL 과 DNL 은 자체보정회로를 통해 모두 1LSB 이내로 측정되었다.

• 대한화장품학회지
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• 제44권4호
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• pp.399-405
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• 2018

다층 및 다중구획 하이드로젤을 설계하여 4D 마스크팩 적용을 위한 자가접힘 특성분석을 수행하였다. 온도민감성 분자를 하이드로젤에 도입하여 팽창비가 다른 두 층으로 구성된 하이드로젤을 제조하였다. 나아가 팽창비 차이를 조절하여 자가접힘 정도가 다른 삼중구획 하이드로젤을 설계하였다. 상온에서 각각 0.03, 0, $0.03mm^{-1}$의 곡률을 갖는 구획화된 하이드로젤은 피부 온도에서 1.33, 0, $1.33mm^{-1}$의 곡률로 변화하여, 안면 밀착성이 현저히 높아지는 것을 확인하였다. 다층 및 다중구획 하이드로젤 제조 기술은 안면의 부위별 굴곡모양에 따라 자가변환이 가능한 맞춤형 4D 마스크팩 구현에 활용될 수 있다.

• JSTS:Journal of Semiconductor Technology and Science
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• 제12권1호
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• pp.1-9
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• 2012

A 10-b 500 MS/s A/D converter (ADC) with a hybrid calibration and error correction logic is described. The ADC employs a single-channel cascaded folding-interpolating architecture whose folding rate (FR) is 25 and interpolation rate (IR) is 8. To overcome the disadvantage of an offset error, we propose a hybrid self-calibration circuit at the open-loop amplifier. Further, a novel prevision digital error correction logic (DCL) for the folding ADC is also proposed. The ADC prototype using a 130 nm 1P6M CMOS has a DNL of ${\pm}0.8$ LSB and an INL of ${\pm}1.0$ LSB. The measured SNDR is 52.34-dB and SFDR is 62.04-dBc when the input frequency is 78.15 MHz at 500 MS/s conversion rate. The SNDR of the ADC is 7-dB higher than the same circuit without the proposed calibration. The effective chip area is $1.55mm^2$, and the power dissipates 300 mW including peripheral circuits, at a 1.2/1.5 V power supply.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2009년도 제38회 동계학술대회 초록집
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• pp.38-38
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• 2010

Ever since the experimental discovery of graphene exfoiliated from the graphite flakes by Geim et at., this area has drawn a lot of attention for its possible application in IT industry. For the growth of graphene, chemical vapor deposition (CVD) has been widely used to fabricate the large area graphene. The lateral size of this graphene can be easily controlled by the size of the metal substrate though the chemical etching to remove this substrate is somewhat troublesome. Another problem which is hard to avoid is the folding at the grain boundary. We will discuss the origin of the folding first and introduce the way to avoid this folding. To solve this problem, we have used the various types of micro-thin metal foils. The precise control of hydro-carbon and the carrier gas results in the formation of the graphene on top of substrate. The thickness of graphene layers can be controlled with the control of gas flow on top of Cu substrate in contrast to the previously reported self-limiting growth $behavior^1$. Uniformity of this graphene layer has been checked by micro-raman spectroscopy and SEM. The size of grain can be enhanced by thermal treatment or use of other metal substrate. The dependence of grain size on the lattice size of the substrate will be discussed. By selecting the shape of substrate, we can grow various types of graphene. We will introduce the micron size graphene tube and its application.

• Journal of Korean Neurosurgical Society
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• 제64권3호
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• pp.367-373
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• 2021

Secondary neurulation (SN) is a critical process to form the neural tube in the posterior region of the body including the tail. SN is distinct from the anteriorly occurring primary neurulation (PN); whereas the PN proceeds by folding an epithelial neural plate, SN precursors arise from a specified epiblast by epithelial-to-mesenchymal transition (EMT), and undergo self-renewal in the tail bud. They finally differentiate into the neural tube through mesenchymal-to-epithelial transition (MET). We here overview recent progresses in the studies of SN with a particular focus on the regulation of cell lineage, self-renewal, and EMT/MET. Cellular mechanisms underlying SN help to understand the functional diversity of the tail in vertebrates.

• 한국농촌간호학회지
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• 제2권2호
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• pp.120-126
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• 2007

Purpose: The objective of this study was to evaluate the effects of leisure programs over 8 weeks on elderly women 60 and over who lived in a rural area. Did the program affect feelings of depression and self-esteem? Method: The leisure programs in this study included rhythm gymnastics for elderly women, recreation, balloon art, paper folding, viewing movies, shuttle cock game, exhibition and evaluation activity. As a Quasi-Experimental study, the design of this study was a Nonequivalent Control Group Pretest-Posttest Design. Results: It was shown that leisure programs for elderly women for 8 weeks, consisting of rhythm gymnastics, self-introduction, hobby activities and recreation can reduce depression and enhance the feeling of self-esteem in elderly women in the rural area. Conclusion: It is concluded that public health centers in rural areas should conduct leisure programs during the farmers' slack season, and that the community halls for elders can contribute to improving the life quality of elderly women by being more affirmative and positive if they develop as healthy and active cultural centers where elderly women will want to come and participate.

• 한국실내디자인학회논문집
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• 제16권2호
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• pp.163-171
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• 2007

The present study approached the characteristics of various space compositions in contemporary residential architecture through the concept of ex-formality, and found that ex-formal spaces are composed through the variation of floor, wall, ceiling or roof and derived four types of ex-formal space composition - ex-cubic space composition using folding, plastic space composition using the plasticity of concrete, atypical space composition using geometric manipulation, and non linear space composition using digital technology. Based on this, additionally, we derived elements expressing the characteristics of ex-formal space composition, which are obliqueness, inclination, flexibility in ex-cubic space composition using folding, plasticity and fluidity in plastic space composition using the plasticity of concrete, ex-construction, dynamism and asymmetry in atypical space composition using geometric manipulation, and flexibility, fluidity, self similarity and plasticity in non linear space composition using digital technology. On the other hand, this study purposed to help understand various space expression patterns of contemporary residential architecture by analyzing how these types of ex-formal space composition and polysemous expression characteristics have been represented in contemporary residential architecture since the 1990s.