http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
Seonghyun Kim,Biju, K P,Minseok Jo,Seungjae Jung,Jubong Park,Joonmyoung Lee,Wootae Lee,Jungho Shin,Sangsu Park,Hyunsang Hwang IEEE 2011 IEEE electron device letters Vol.32 No.5
<P>We investigated the effect of scaling down the device area of WO<I>x</I> resistive random-access memory (RRAM) devices on their switching characteristics. Device dimensions were successfully scaled down to 50 nm using a via-hole structure with additional Al<SUB>2</SUB>O<SUB>3</SUB> sidewall process. As compared to the microscale devices, the nanoscale devices exhibited a distinct switching mechanism and better memory performance, such as improved switching uniformity, larger memory window, and stable endurance characteristics for up to 10<SUP>7</SUP> cycles. This improvement can be explained by a uniform interfacial switching mechanism in nanoscale device; this is in contrast with the defect-induced filamentary switching mechanism observed in microscale devices. In this way, the intrinsic switching properties of RRAMs were obtained by scaling down of the device area, indicating that RRAMs hold considerable promise for future applications.</P>
Daeseok Lee,Joonmyoung Lee,Seungjae Jung,Seonghyun Kim,Jubong Park,Biju, K. P.,Minhyeok Choe,Takhee Lee,Hyunsang Hwang IEEE 2011 IEEE transactions on nuclear science Vol.58 No.6
<P>In this study, we investigated proton irradiation effects on resistive random access memory (ReRAM) comprising ZrO<SUB>x</SUB>/HfO<SUB>x</SUB> stacks. After irradiation, changes of current were observed in the initial state (IS). From the electrical conduction mechanism in the IS, we have concluded that the different initial conditions of the active layer lead to different radiation effects. The radiation-induced leakage paths have been concluded as main origin of the increased leakage current, whereas radiation-induced charge trapping is dominant fact of the decreased leakage current in the IS. From the results of noise analysis in the low resistance state (LRS) and high resistance state (HRS), we observed that the radiation effects became negligible because of the formed local conducting path during forming process.</P>
Myungwoo Son,Joonmyoung Lee,Jubong Park,Jungho Shin,Godeuni Choi,Seungjae Jung,Wootae Lee,Seonghyun Kim,Sangsu Park,Hyunsang Hwang IEEE 2011 IEEE electron device letters Vol.32 No.11
<P>We herein present a nanoscale vanadium oxide (VO<SUB>2</SUB>) device with excellent selector characteristics such as a high on/off ratio (>; 50), fast switching speed (<; 20 ns), and high current density (>; 10<SUP>6</SUP> A/cm2). Owing to extrinsic defects, a large-area device with a 20-nm-thick VO<SUB>2</SUB> layer underwent an electrical short. In contrast, after scaling the device active area (<; 5 × 10<SUP>4</SUP> nm<SUP>2</SUP>), excellent switching uniformity was obtained. This can be explained by the reduced defects and the metal-insulator transition of the whole nanoscale VO<SUB>2</SUB>. By integrating a bipolar resistive random access memory device with the VO<SUB>2</SUB> selection device, a significantly improved readout margin was obtained. The VO<SUB>2</SUB> selection device shows good potential for cross-point bipolar resistive memory applications.</P>
Minseok Jo,Seonghyun Kim,Seungjae Jung,Ju-Bong Park,Joonmyoung Lee,Hyung-Suk Jung,Choi, R.,Hyunsang Hwang IEEE 2010 IEEE electron device letters Vol.31 No.4
<P>The effect of fast components in the threshold-voltage shift (¿V<SUB>th</SUB>) induced by electrical stress on the lifetime of bias temperature instability (BTI) is investigated in metal-oxide-semiconductor field-effect transistors with high-k gate dielectrics using dc and pulsed measurements. The empirical results confirm that the initial fast ¿V<SUB>th</SUB> (¿V<SUB>th,fast,ini</SUB>.) does not contribute to long-term device degradation under operating voltage conditions. Therefore, ¿V<SUB>th</SUB> is corrected by eliminating the initial ¿V<SUB>th,fast,ini</SUB>. With this adjustment, the effect of measurement time (t<SUB>m</SUB>) on the corrected ¿V<SUB>th</SUB> (¿V<SUB>th,corr</SUB>.) is negligible. However, compared with the lifetime estimates made using ¿V<SUB>th,corr</SUB>., the dc measurements still tend toward overestimation under low voltage stress because of the ¿V<SUB>th,fast,str</SUB>. component induced by stress (not the initial ¿V<SUB>th,fast,ini</SUB>.)In conclusion, it may be stated that the ¿V<SUB>th,fast,str</SUB>. component could play a critical role in BTI tests conducted under operating voltage conditions.</P>
A Bayesian Spatial Contamination Model
Jonghyun Na,Taekseon Ryu,Joonmyoung Kim,Hansuk Kim,Manjae Kwon,Yongsung Joo 한국자료분석학회 2022 Journal of the Korean Data Analysis Society Vol.24 No.3
In environmental research, it is often the case that to cluster observations into environmentally polluted and natural groups is an important issue. The Bayesian contamination model which adopts a multivariate mixture regression model has been developed in that it aims to cluster observations and estimate the average amount of pollution. However, because the Bayesian contamination model does not take spatial correlations between observations into consideration, a Bayesian spatial contamination model is proposed. A simulation study was conducted showing that the proposed model has an advantage over the Bayesian contamination model in terms of biases and RMSE of estimators of the logistic regression parameters. We applied the proposed model into environmental data and confirmed the improvement on the model fit. Also, the clustering was reasonably performed from the environmental perspective, which was coherent with the fact that the underground water flows from the southwest side to the northeast side. This model is expected to be utilized effectively to monitor the quality of a ground or groundwater and capture the heterogeneity in it which is suspected of environmental pollution especially when the interested site consists of areas with strong spatial dependency.
Effect of Program/Erase Speed on Switching Uniformity in Filament-Type RRAM
Jungho Shin,Jubong Park,Joonmyoung Lee,Sangsu Park,Seonghyun Kim,Wootae Lee,Insung Kim,Daeseok Lee,Hyunsang Hwang IEEE 2011 IEEE electron device letters Vol.32 No.7
<P>We investigated the effect of program/erase speed on switching uniformity in filament-type resistive memory with Mo/SiO<SUB>x</SUB>/Pt structure. The RRAM device exhibits a large on/off ratio (>; 10<SUP>5</SUP>), good data retention properties even at 200°C, and stable pulse-switching endurance up to 106 cycles. In comparison with slow switching operation, fast switching operation achieves more uniform program/erase performance in filament-type resistive memory. In order to determine the relationship between the switching speed and the uniformity, we carried out an effective analysis of real pulse operation.</P>
Characteristics of Traps Induced by Hot Holes Under Negative-Bias Temperature Stress in a pMOSFET
Minseok Jo,Man Chang,Seonghyun Kim,Seungjae Jung,Ju-Bong Park,Joonmyoung Lee,Dong-Jun Seong,Hyunsang Hwang IEEE 2009 IEEE electron device letters Vol.30 No.11
<P>We investigated the generation and recovery process of traps in pMOSFETs under negative-bias temperature (NBT) stress by using pulsed and dc measurements. The behavior of generated traps was studied as a function of applied body bias (<I>V</I> <SUB>B</SUB>). The fast components induced with the application of a positive <I>V</I> <SUB>B</SUB> were independent of measurement time (<I>t</I> <SUB>m</SUB>), while the results from devices with no applied <I>V</I> <SUB>B</SUB> showed a strong dependence on <I>t</I> <SUB>m</SUB>. This suggests that the fast components of additional traps generated by a positive <I>V</I> <SUB>B</SUB> can be attributed to interface states (<I>N</I> <SUB>it</SUB>) at the Si/SiO<SUB>2</SUB> interface. Based on the results of recovery characteristics with an intentional measurement delay, the recovery of <I>N</I> <SUB>it</SUB> is relatively slow, initiating on the scale of a few milliseconds.</P>
토양 내 오염물질 농도 예측을 위한 베이지안 벌점 스플라인
유택선(Taekseon Ryu),나종현(Jonghyun Na),김준명(Joonmyoung Kim),윤태현(Taehyun Yoon),이정호(Jeongho Lee),김한석(Han-Suk Kim),권만재(Manjae Kwon),주용성(Yongsung Joo) 한국자료분석학회 2022 Journal of the Korean Data Analysis Society Vol.24 No.5
토양오염의 진단을 위해서는 조사 부지의 토양 내 오염물질의 분포를 정확히 파악할 필요가 있다. 하지만 조사 부지에서 관측이 가능한 모든 지점을 생화학적으로 조사하는 것은 현실적으로 불가능하므로 조사 부지 내 일부 선정된 지점에서 얻은 자료를 바탕으로 공간예측모형을 통해 조사 부지의 토양 내 오염물질 농도를 예측하게 된다. 토양 자료는 자료의 특성상 자료의 크기가 충분히 크지 않은 경우가 종종 발생하고, 이에 따라 공간예측의 정확성이 크게 감소할 수 있다. 따라서 본 연구에서는 이러한 문제를 해결하고자 환경부에서 제공하는 토양측정망 자료를 사전 정보로 활용하여 조사 부지의 토양 내 오염물질 농도를 예측하는 베이지안 벌점 스플라인 모형을 제안한다. 또한, 제안 모형의 성능을 평가하기 위해 RMSE를 비롯한 여러 성능 평가 지표를 이용하여 제안 모형과 여러 비교 모형과의 표본 자료 크기 별 예측 정확성을 비교하였다. 성능 평가 결과, 제안 모형의 성능이 비교 모형들에 비해 유용한 성능을 보임을 확인할 수 있었다. 특히, 표본 자료의 크기가 비교적 작을수록 제안 모형의 성능이 비교 모형들이 비해 더욱 준수한 성능을 보였다. 따라서 조사 부지에 대한 토양 자료가 상대적으로 부족한 토양 조사의 초기 단계에서 토양 내 오염물질의 분포를 파악하고자 할 때 제안 모형의 사용을 제안한다. For the diagnosis of soil contamination, it is necessary to accurately understand the distribution of pollutants in the soil of the survey site. However, since it is practically impossible to investigate all observable points in the survey site, the concentration of pollutants in the soil of the survey site is predicted through a spatial prediction model based on data obtained from some selected points in the survey site. However, due to the nature of the soil data, the size of the data is often insufficient, which can greatly reduce the accuracy of spatial prediction. Therefore, in this study, to solve this problem, we propose a Bayesian penalized spline model that predicts the concentration of contaminants in the soil of the survey site by using the soil quality monitoring network data provided by the Ministry of Environment(MOE) in Korea as prior information. In addition, in order to evaluate the performance of the proposed model, RMSE, MAE, MAPE were used to compare the prediction accuracy by data size with several comparative models. As a result of the performance evaluation, it was confirmed that the performance of the proposed model showed better performance than the comparative models. In particular, the smaller the data size, the better the performance of the proposed model compared to the comparative models. Therefore, the use of the proposed model can be considered when trying to understand the distribution of pollutants in the soil at the initial stage of soil survey, where soil data for the survey site is relatively scarce.
Wootae Lee,Jubong Park,Myungwoo Son,Joonmyoung Lee,Seungjae Jung,Seonghyun Kim,Sangsu Park,Jungho Shin,Hyunsang Hwang IEEE 2011 IEEE electron device letters Vol.32 No.5
<P>We have investigated silicon carbide (SiC) as a new programmable metallization cell material for nonvolatile memory applications. Our Cu/SiC/Pt devices showed bipolar resistive switching; the conduction mechanisms can be explained by the formation of a Cu filament and Poole-Frenkel emission in the low-resistance and high-resistance states, respectively. In particular, our devices showed excellent state stability, e.g., nondestructive readout at various stress voltages, excellent retention characteristics at 150°C for 10<SUP>4</SUP> s, and stable memory operation at high ambient temperature. We attribute this state stability to the SiC's high chemical stability and the ability to act as a Cu diffusion barrier.</P>