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A Digital TCXO with New Trimming Method
Hyungcheol Shin,Min-Kyu Jeon,Kyungmi Lee 에스케이텔레콤 (주) 2000 Telecommunications Review Vol.10 No.6
Recently, the demand for the stable temperature compensated crystal oscillators (TCXO) is increasing more and more and digital TCXOs (DTCXO) have been studied extensively because of their higher frequency accuracy and onechip implementation possibility. To develop a VLSI TCXO circuit, the DTCXO using capacitor array which is directly controlled by the digital code from the memory was proposed and how to organize the capacitor array has been studied. In this work, a new capacitor array scheme, called TACA (temperature compensated capacitor array) is proposed. It guarantees monotonicity and saves the silicon area at the same time. We also have developed TCXO, which can be used over wide range of frequency. The oscillator and the capacitor array were fabricated with a 0.5μm CMOS process. Complete digital trimming of the DTCXO with 0.2ppm trimming accuracy was achieved.
Optimization of Silicon Quantum Dot Fabrication on Oxide and Nitride Films
Hyungcheol Shin,Jongho Lee 한국정보과학회 1999 Journal of Electrical Engineering and Information Vol.4 No.4
We have developed an LPCVD process of forming small-sized, high-density silicon quantum dots by investigating the effect of substrate type, chemical treatment, deposition temperature, and deposition time. Repeated results were obtained after several experiments under the same conditions when fabricating uniform quantum dots on Si₃N₄ and SiO₂ films. This ability to precisely control the size, density, and uniformity indicates the feasibility of practical nano-crystal non-volatile memory.
Analytical Thermal Noise Model of Deep-submicron MOSFETs
Hyungcheol Shin,Seyoung Kim,Jongwook Jeon 대한전자공학회 2006 Journal of semiconductor technology and science Vol.6 No.3
This paper presents an analytical noise model for the drain thermal noise, the induced gate noise, and their correlation coefficient in deepsubmicron MOSFETs, which is valid in both linear region and saturation region. The impedance field method was used to calculate the external drain thermal noise current. The effect of channel length modulation was included in the analytical equation. The noise behavior of MOSFETs with decreasing channel length was successfully predicted from our model.
Achieving long-term stable perovskite solar cells <i>via</i> ion neutralization
Back, Hyungcheol,Kim, Geunjin,Kim, Junghwan,Kong, Jaemin,Kim, Tae Kyun,Kang, Hongkyu,Kim, Heejoo,Lee, Jinho,Lee, Seongyu,Lee, Kwanghee Royal Society of Chemistry 2016 ENERGY AND ENVIRONMENTAL SCIENCE Vol.9 No.4
<P>Despite recent reports of high power conversion efficiency (PCE) values of over 20%, the instability of perovskite solar cells (PSCs) has been considered the most serious obstacle toward their commercialization. By rigorously exploring the self-degradation process of planar-type PSCs using typical metal electrodes (Ag or Al), we found that the corrosion of the metal electrodes by inherent ionic defects in the perovskite layers is a major origin of intrinsic device degradation even under inert conditions. In this work, we have developed a new concept of a chemical inhibition in PSCs using amine-mediated metal oxide systems and succeeded in chemically neutralizing mobile ionic defects through mutual ionic interaction. As a consequence, we realized planar-type PSCs with long-term stability that maintain nearly 80% of their initial PCEs even after 1 year (9000 h) of storage under nitrogen and 80% of their initial PCEs after 200 h in ambient conditions without any encapsulation.</P>
민형철(Hyungcheol Min),이영곤(Younggon Lee),정해동(Haedong Jeong),박승태(Seungtae Park),이승철(Seungchul Lee) 한국소음진동공학회 2014 한국소음진동공학회 학술대회논문집 Vol.2014 No.10
In the process of MLCC manufacturing, MLCC stacking process is the key process of making high quality MLCC. Since MLCC is small components, the entire process of MLCC stacking process is minute and sensitive to micro errors. To prevent micro error, we suggest condition-based monitoring which quantifies error based on feature extraction and quantifying error method. As results, it has been shown that the suggested algorithm has effectiveness of condition based monitoring of MLCC stacker.