Quantitative analysis of charge trapping and classification of sub-gap states in MoS₂ TFT by pulse <i>I</i>–<i>V</i> method

Park, Junghak,Hur, Ji-Hyun,Jeon, Sanghun IOP 2018 Nanotechnology Vol.29 No.17

<P>The threshold voltage instabilities and huge hysteresis of MoS<SUB>2</SUB> thin film transistors (TFTs) have raised concerns about their practical applicability in next-generation switching devices. These behaviors are associated with charge trapping, which stems from tunneling to the adjacent trap site, interfacial redox reaction and interface and/or bulk trap states. In this report, we present quantitative analysis on the <I>electron</I> charge trapping mechanism of MoS<SUB>2</SUB> TFT by fast pulse <I>I</I>–<I>V</I> method and the space charge limited current (SCLC) measurement. By adopting the fast pulse <I>I</I>–<I>V</I> method, we were able to obtain effective mobility. In addition, the origin of the trap states was identified by disassembling the sub-gap states into interface trap and bulk trap states by simple extraction analysis. These measurement methods and analyses enable not only quantitative extraction of various traps but also an understanding of the charge transport mechanism in MoS<SUB>2</SUB> TFTs. The fast <I>I</I>–<I>V</I> data and SCLC data obtained under various measurement temperatures and ambient show that electron transport to neighboring trap sites by tunneling is the main charge trapping mechanism in thin-MoS<SUB>2</SUB> TFTs. This implies that interfacial traps account for most of the total sub-gap states while the bulk trap contribution is negligible, at approximately 0.40% and 0.26% in air and vacuum ambient, respectively. Thus, control of the interface trap states is crucial to further improve the performance of devices with thin channels.</P>

A Family-to-family Messaging Service Framework based on Smart TV

Junghak Kim,Sangtaick Park,Jinwoo Hong 한국정보통신학회 2014 2016 INTERNATIONAL CONFERENCE Vol.6 No.1

This paper proposes a messaging service framework based on smart TV where a family group can exchange messages or certain data with other family groups. A family group can be mapped to a TV terminal. And the TV terminal may be characterized as a representative device of the family group. A member of the family group can be mapped to a personal hand-held device such as smart phone and tablet. In the proposed framework, a family member can send messages to other family groups or particular members of other family groups. In a family group, the family-targeted messages are naturally shared among the family members, but the member-targeted messages are transmitted to only a particular member. In the proposed messaging service, all messages are exchanged and shared among only family groups or members invited in a conversation room. This paper also shows an implementation and demonstration example with an android and HTML5-based smart TV platform.

Network-Assisted Management of Power-Efficient Set-Top Boxes for Enhancing User Experience

Park, Hyunho,Kim, Junghak,Jung, Eui-Suk,Kwon, Eunjung,Lee, Yong-Tae IEEE 2018 IEEE transactions on consumer electronics Vol.64 No.1

<P>For the power-efficient set-top boxes, passive-standby mode was proposed as the lowest power mode. However, the power-efficient set-top box in the passive-standby mode provides low quality of user experience (e.g., update problem and latency for full activation). In this paper, network-assisted management method is proposed to enhance user experience by reducing the set-top boxes’ latency for full activation and by facilitating update for the set-top boxes. The network-assisted management enables a set-top box assistance server (SBAS) to analyze the frequently used time of the set-top box and to receive update schedule from the set-top box operator. The SBAS schedules standby modes of the set-top boxes for enhancing user experience by using the frequently used time and update schedule.</P>

A rapid, simultaneous and quantitative analysis of 26 ginsenosides in white and red Panax ginseng using LC–MS/MS

Lee Junghak,Han Heeju,Yuan Xiu,Park Eunyoung,Lee Jonghwa,Kim Jeong-Han 한국응용생명화학회 2021 Applied Biological Chemistry (Appl Biol Chem) Vol.64 No.1

A quantitative analysis of ginsenoside is very important for ginseng studies because each ginsenoside shows different medical activity and metabolic pathway. In this study, a rapid, simultaneous, and quantitative analysis of 26 ginsenosides (Rb1, Rb2, Rc, Rd, Re, Rf, Rg1, Rg2(R), Rg2(S), Rg3(S), Rg3(R), Rg5, Rg6, Rh1(R), Rh1(S), Rh2(R), Rh2(S), F1, F2, F3, F4, K, Mc, PPT(S), XVII, and Y) in white, and red Panax ginseng was established using multiple reaction monitoring (MRM) mode on ultra-high-performance liquid chromatography-tandem mass spectrometry (UHPLC–MS/MS). The mobile phase of water and methanol containing 0.1% formic acid and HSS T3 C18 analytical column was used for the chromatographic separation. The four sets of stereoisomers were successfully separated within a 26-min run time, eluting the S-isomer faster than the R-isomer with higher concentration. The ginseng extract was diluted by 100, 400 and 8000 times to fit in the calibration range and quantitated by the standard addition method. Matrix matched calibration by mixing 64 μL of the ginseng extract with 16 μL of the standard solution was used for compensating the matrix effect. Such quantitation methodology using dilution, standard addition and matrix matching resulted in precise and unambiguous quantitation of 26 ginsenosides in ginseng products. Major ginsenosides were observed at relatively higher concentrations in red Panax ginseng and the Mc was detected and quantitated for the first time in this study. The comprehensive quantitation system established in this study will contribute to quality evaluation, breeding and culturing, and quantitative metabolomics study of ginseng.

Development of the analytical method for Hexythiazox in of herbal medicine Angelica dahurica Bentham et Hooker using HPLC

Boeun Ju,Junghak Lee,Eunyoung Park,Xiu Yuan,Mai Rehan,Rakdo Go,Heeju Han,Jeong-Han Kim 한국농약과학회 2019 한국농약과학회 학술발표대회 논문집 Vol.2019 No.10

고주파수 청력손실이 말소리인지에 미치는 영향

박진희(Jinhee Park),이정학(Junghak Lee) 한국언어청각임상학회 2001 Communication Sciences and Disorders Vol.6 No.1

청력손실 중 감각신경성 난청은 고주파수의 손실이 가장 보편적이며 그에 따른 말소리인지도도 저조한 것으로 알려져 있다. 본 연구에서는 고주파수 난청을 모의실험한 정상군과 실제의 고주파수 난청군을 대상으로 말소리인지도를 검사하여 고주파수 난청이 말소리인지에 미치는 영향을 살펴보았다. 정상인 20명을 대상으로 저음여과기(low- pass filter)를 사용하여 각 절단 주파수 1, 1.5, 2, 3, 4kHz를 기준으로 여과시켜 고주파수 난청을 모의실험하였고 10명의 고주파수 난청인을 대상으로 말소리인지도 검사를 실시하여 자극강도별로 비교하였다. 모의 실험군에서는 자극주파수를 여과하지 않은 상태(no- filtering)와 비교할 때 절단주파수 3kHz이상에서는 말소리인지도가 비슷하게 좋았으며 절단 주파수 2kHz이하에서는 자극제시강도가 커져도 고심도의 말소리인지도 손실이 나타났다. 최고의 말소리인지도는 약 40- 50dBHL에서 보였으며 70dBHL에서는 모든 주파수대역에서 말소리인지가 저하되어 어음의 왜곡현상을 보였다. In th e cas e of high fr e quen cy he ar ing los s , th e pr imary goal of he ar ing aid fitting s tr ategies is t o mak e th e sp e e ch s ign al audible thr ough pr oviding high - fr e quen cy amp - lification . Howev er , an in cr eas e in audibility does n ot always pr ovide a complete r es tor ation of sp e e ch r e cognition for all h e ar ing - imp air e d lis ten ers . T h e purp os e of this s tudy was to determine th e optimal fr e quen cy r es p ons e ch ar acter is tics of s p e ech r e cognition ability for th e lis ten ers with high - fr equency h e ar ing los s . T wenty adults with n ormal h ear ing and ten adults with high - fr e quen cy s ens or in eur al h e ar ing los s p ar ticip ate din this s tudy . T wenty normal s ubje cts cons is te d of ten males an d ten females with a mean age of 30 ye ars (r anging fr om 25 to 4 5 y ears ). T en h e ar ing - imp air ed adults cons is te d of eight males an d two females with a me an age of 53 y ears (r anging fr om 35 to 80 y e ars ). F or th e normal he ar ing gr oup , high - fr e quen cy h e ar ing los s es wer e s imulat ed. T h e sp e e ch s timuli wer e pr es ent ed t o th e s ubje cts under th e low- p as s filt er e d con ditions with n o- filter ing and five cut - off fr e quen cies of 1, 1.5 , 2 , 3 , an d 4kHz. T h e pr es entation levels wer e var ie d fr om 20 dBHL to 70 dBHL. Wor d r e cognition s cor es (WRSs ) wer e obtain ed with s ix con ditions at e ach pr es ent ation lev el. For th e h e ar ing imp ar e d gr oup , WRSs wer e obt ain e d at the r egular conver s at ion lev el of 50dBHL. Gener ally , th e s imulate d h e ar ing imp air e d gr oup s h owe d high WRSs at th e con dition of no filter ing th an at th e condit ions of v ar ious filter ing . Wh en th e con dition of n o filter ing was comp ar e d with each filter ing con dition , th e differ en ce was s t atis tically s ignificant (p <.0 1) at all pr es ent ation levels for the cut - off fr e quen cy b elow 2kHz. For th e cut - off fr e quen cies at 3 an d 4kHz, the differ en ce was s tatis tically s ignificant (p <.0 1) at all pr es ent ation lev els except 40 an d 50 dBHL. As th e cut - off fr e quen cy in cr e as e d, WRSs wer e incr e as ed at all pr es entation levels . At th e pr es entation lev els of 40 - 50dBHL, h owev er , th e WRSs at th e condition with out filter ing wer e n ot s ignificantly differ ent fr om thos e at th e con dition filter ing at 3 - 4kHz. T h e WRSs for the s imulate d h e ar ing los s gr oup wer e s imilar t o th os e for th e he ar ing imp air e d gr oup at the pr es ent ation level of 50 dBHL with th e cut - off fr e quency of 2kHz. T h es e r es ults s ugg es t that alth ough th e acous tic information ab ov e 3kHz may n ot b e as cr itical as that below 3kHz at th e n ormal convers ation lev el(40 - 50 dBHL), it may b e imp or t ant to unders tan d whis p er ing or loud v oices . For th e gen er alization of the r es ults , mor e dat a fr om the h e ar ing - imp ar e d sh ould b e colle cte d.

Photosensitivity of InZnO thin-film transistors using a solution process

Choi, Jongwon,Park, Junghak,Lim, Keon-Hee,Cho, Nam-kwang,Lee, Jinwon,Jeon, Sanghun,Kim, Youn Sang American Institute of Physics 2016 Applied Physics Letters Vol.109 No.13

다중매체 멀티미디어 재난정보 생성 및 전달 서비스 플랫폼

박현호(Hyunho Park),권은정(Eunjung Kwon),김정학(Junghak Kim),정의석(Eui-Suk Jung),이현우(Hyun-Woo Lee),이용태(Yong-Tae Lee) 한국방송·미디어공학회 2017 한국방송공학회 학술발표대회 논문집 Vol.2017 No.6

Test-Retest Reliability of Word Recognition Score Using Korean Standard Monosyllabic Word Lists for Adults as a Function of the Number of Test Words

Kim, Jinsook,Lee, Junghak,Lee, Kyoung Won,Bahng, Junghwa,Lee, Jae Hee,Choi, Chul-Hee,Cho, Soo Jin,Shin, Eun Yeong,Park, Jeonghye The Korean Audiological Society 2015 Journal of Audiology & Otology Vol.19 No.2

<P><B>Background and Objectives</B></P><P>The purpose was to establish the test-retest reliability of word recognition score (WRS) using Korean standard monosyllabic word lists for adults (KS-MWL-A) recently developed based on the international standard for speech audiometry (ISO 8253-3:2012).</P><P><B>Subjects and Methods</B></P><P>Subjects consisted of 159 adults aged to 18 to 25 years with normal hearing sensitivity. WRSs were obtained in 2 dB steps from the level of speech recognition thresholds to the level of 86% correct responses or greater. After one or two weeks, retest was performed. Correlation, confidence interval (CI) and prediction interval (PI) were calculated for the reliability.</P><P><B>Results</B></P><P>Correlation coefficients were 0.88 for 50 test words, 0.76 for 25 and 0.61 for 10 words. Results also showed that 95% CIs and PIs were narrower for 25 and 50 test words than those for 10 test words.</P><P><B>Conclusions</B></P><P>Korean WRS using the KS-MWL-A has high reliability for 25 and 50 test words, but relatively low for 10 words. It suggested that 95% CIs for each test words would be criteria for significant differences in WRS for groups and 95% PIs at each score of WRS could be utilized for a considerable difference for each individual at retest.</P>

Photoresponse of an oxide semiconductor photosensor

Ahn, Seung-Eon,Park, Sungho,Kim, Taeho,Park, Junghak,Jeon, Sanghun American Institute of Physics 2015 Journal of Vacuum Science & Technology. B Vol.33 No.3