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Highly Scalable NAND Flash Memory Cell Design Embracing Backside Charge Storage
Wookhyun Kwon,In Jun Park,Changhwan Shin 대한전자공학회 2015 Journal of semiconductor technology and science Vol.15 No.2
For highly scalable NAND flash memory applications, a compact (4F2/cell) nonvolatile memory architecture is proposed and investigated via threedimensional device simulations. The back-channel program/erase is conducted independently from the front-channel read operation as information is stored in the form of charge at the backside of the channel, and hence, read disturbance is avoided. The memory cell structure is essentially equivalent to that of the fully-depleted transistor, which allows a high cell read current and a steep subthreshold slope, to enable lower voltage operation in comparison with conventional NAND flash devices. To minimize memory cell disturbance during programming, a charge depletion method using appropriate biasing of a buried back-gate line that runs parallel to the bit line is introduced. This design is a new candidate for scaling NAND flash memory to sub-20 nm lateral dimensions.
Anisotropic X-ray Rocking Curve Due to a Damaged Surface Layer in a Freestanding GaN Thick Film
seunghwan Park,jiho Chang,dongchoel Oh,G. Fujimoto,H. Goto,Hideyuki Suzuki,Takafumi Yao,Takashi Hanada,Tsutomu Minegishi,wookhyun Lee 한국물리학회 2006 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.49 No.3
The structural deformation of freestanding GaN film has been investigated. The specimen was grown on an Al2O3 substrate by using hydride vapor phase epitaxy (HVPE) and was self-detached during the growth. the atomic force microscopy (AFM) image showed much mechanical damages on the surface, which was presumably generated by the surface polishing process. After chemical etching, the near-band-edge to yellow-band (NBE/YB) luminescence intensity ratio was greatly increased. Also, using high resolution X-ray diraction (HRXRD), we found that the 2-! scan of (0002) reflection asymmetrically broadened at low diraction angles, which indicated that a damaged surface layer existed in the film with residual compressive strain. Moreover, a more detailed X-ray analysis showed that the surface had a concave curvature. We concluded that structural distortion of GaN could induce a serious deformation, which could aect not only the structural but also the optical and the electrical properties of the film.
Highly Scalable NAND Flash Memory Cell Design Embracing Backside Charge Storage
Kwon, Wookhyun,Park, In Jun,Shin, Changhwan The Institute of Electronics and Information Engin 2015 Journal of semiconductor technology and science Vol.15 No.2
For highly scalable NAND flash memory applications, a compact ($4F^2/cell$) nonvolatile memory architecture is proposed and investigated via three-dimensional device simulations. The back-channel program/erase is conducted independently from the front-channel read operation as information is stored in the form of charge at the backside of the channel, and hence, read disturbance is avoided. The memory cell structure is essentially equivalent to that of the fully-depleted transistor, which allows a high cell read current and a steep subthreshold slope, to enable lower voltage operation in comparison with conventional NAND flash devices. To minimize memory cell disturbance during programming, a charge depletion method using appropriate biasing of a buried back-gate line that runs parallel to the bit line is introduced. This design is a new candidate for scaling NAND flash memory to sub-20 nm lateral dimensions.
에너지산업현장에서의 재난대응안전한국훈련시 재난훈련시스템 적용성 검토 사례조사
박남희,여욱현,김태환,Park, Namhee,Yeo, Wookhyun,Kim, Taehwan 한국재난정보학회 2018 한국재난정보학회 논문집 Vol.14 No.2
연구목적: 본 연구는 에너지산업현장에서 재난 발생에 대비하여 훈련하는 안전한국훈련 상황에서 훈련시 사용할 수 있는 재난훈련시스템을 필요한 곳에 적절하게 사용할 수 있는 방안을 모색하는 것을 목적으로 한다. 연구방법: 논문, 보고서, 통계자료 등을 조사하고 현장방문하여 훈련상황을 조사하였다. 연구결과: 재난훈련시스템을 활용한 토론기반 훈련과 실행기반 훈련이 계획수립부터 자체평가까지 가능하게 잘 이루어지고 있었다. 결론: 재난훈련시스템은 재난 발생에 대비하는 기관의 자체 훈련, 재난대응안전한국훈련시에는 평가활동까지 복합적으로 활용할 수 있는 시스템으로 그 사용성을 높여 평소 활용 범위를 넓혀야 한다. Purpose: The purpose of this study is to find a way to use the disaster drill system that can be used in the training in the required situation in the safety training situation in the safety industry to prepare for the disaster in the energy industry field by utilizing the developed system. Method: In order to accomplish the purpose of the research, I investigated the papers, reports, statistical data, and visited the site to investigate the training situation. Results: Disaster response safety Korean training is not only responding to disasters but also cooperating activities with local governments and related organizations. The contents are complex, diverse, and multifaceted. Conclusion: The disaster training system should be applied to the self training of the organization to prepare for the disaster and the safety training for disaster response in Korea.
Taehwan Kim,Namhee Park,Wookhyun Yeo 한국재난정보학회 2012 한국재난정보학회 논문집 Vol.8 No.4
본 연구의 목적은 민방위 사태 발발시 준비 방안의 하나로서 비상생활지원 키트를 개발하여 국민의 안전과 안녕을 확보할 수 있는 기초 준비 방안을 모색하는 것이다. 민방위대피소에서 짧게는 2시간부터 길게는 6일 정도를 생활하는 것을 감안하면 시설이용자들의 기본적인 생존권을 위해 비상생활지원용 식량 및 기타 물품이 필요하다. 1인당 3일 최소 비상생활지원키트는 개인용 무게는 4.85kg, 국가 및 지자체(정부)는 2.65kg을 분담하게 하고 그 구성은 총 8개 분류 26개 항목으로 식품, 피복, 화생방용품, 방한용품, 개인위생용품, 의약품, 공구, 통신용품 등으로 구성한다.
김태형(Tae-Hyung Kim),안욱현(Wookhyun Ahn),박종인(Jong-In Park),육종관(Jong-Gwan Yook) 한국전자파학회 2020 한국전자파학회논문지 Vol.31 No.3
대형 드론의 고전력 무선충전을 위한 광역 무선충전 스테이션을 연구하였다. 수신 코일의 전체 크기는 420×420×10 mm 이고, 드론의 다리 부분에 연결하였다. 송신 코일은 균일한 자기장 세기 및 높은 전송 효율 유지를 위하여, 서로 다른 모양을 갖는 코일 3개를 개별적으로 최적화한 후 직렬로 결합하였다. 송신 코일의 전체 크기는 1,000×1,000×105 mm이며, 케이스를 포함한 두께이다. 최종 설계된 송, 수신 코일의 품질 계수는 각각 120, 54이며, 수직 및 수평 이동에 따라 고효율 특성을 나타내었다. 코일 간 중심을 기준으로, 전송 효율은 수직 거리 50 mm에서 91 %, 300 mm에서 80 %가 나타났으며, 수신 코일이 충전 영역의 가장자리로 수평 이동했을 때에도 89.5 %로 고효율 특성이 나타났다. 전력공급기, 송, 수신 모듈, 부하 등을 연결한 상태에서, 174.7 W의 전력을 입력하였을 때, 수신단에서 측정된 전력은 120.3 W로 시스템 효율 69 %이다. 더불어, 무선충전 시 발생하는 전자기파가 EMI 기준 이하로 측정되었다. This study investigates high-power wireless power transfer(WPT) with a wide charging area for large drones. The overall size of the receiving coil(Rx-coil) connected to the leg of the drone on the bottom side is 420×420×10 mm. Transmitting coils(Tx-coils) of three different shapes are individually optimized and combined to achieve a uniform magnetic field intensity and high power transfer efficiency(PTE) retention rate. The overall dimension of %the Tx-coil including the case thickness is 1,000×1,000×105 mm. The quality factors of the optimized Tx- and Rx-coils are 120 and 54, respectively, expressing a high PTE according to the transmission and misalignment distances. Based on the center between the coils, the PTE is 91 % and 80 % at a transmission distance of 50 mm and 300 mm, respectively. The PTE is 89.5 % when the Rx-coils are positioned at a misalignment distance of 285 mm, which indicates the edge of the Tx-coil in the charging area. The coils are connected to various equipment(e.g., signal source, Tx- and Rx-modules, load, etc.) to verify the WPT system. The system efficiency considering loss is 69 % because the input and output powers are 174.7 W and 120.3 W, respectively. In addition, an electromagnetic wave is measured below the electromagnetic interference standard.
Chang-Ki Baek,Bomsoo Kim,Son, Y.,Wookhyun Kwon,Chan-Kwang Park,Park, Y.J.,Hong Shick Min,Kim, D.M. IEEE 2006 IEEE electron device letters Vol.27 No.3
<P>The cycling induced interface states in floating-gate EEPROM cells are reliably extracted by implementing accurate program/erase stresses in the reference cell. The interface states measured directly from the memory cell via charge pumping are shown different from those obtained conventionally from the reference cell. The reasons for these different levels of extraction are elucidated and a new method is presented for accurate determination of interface trap density. The technique is based on introducing the equivalent gate voltage with offset voltage at the reference cell by which to simulate realistically the cycling stresses as occur in the flash memory cell itself.</P>
Invasive Precise Pulse Wave Velocity Measurement
Taewoo Nam,Jongman Cho,Junghyeon Choi,Junho Park,Wookhyun Cho 대한전자공학회 2007 ITC-CSCC :International Technical Conference on Ci Vol.2007 No.7
Pulse wave velocity (PWV) is a basic parameter in the dynamics of pressure and flow wave traveling in arteries. But it is difficult to measure the pulse wave transmission time between coronary arterial proximal and distal point by manual method using a graph on which pulse wave and ECG are recoded. The system that can measure PWV was developed and the experiment was carried out for one patient to validate the accuracy of the measured coronary arterial PWV. The average value of the measured coronary arterial PWV was 936.571±105.161 ㎝/sec.