Investigation of channel mobility in AlGaN/GaN high-electron-mobility transistors

Chang, Sung-Jae,Kang, Hee-Sung,Lee, Jae-Hoon,Yang, Jie,Bhuiyan, Maruf,Jo, Young-Woo,Cui, Sharon,Lee, Jung-Hee,Ma, Tso-Ping Institute of Pure and Applied Physics 2016 Japanese Journal of Applied Physics Vol.55 No.4

<P>We have investigated the channel mobility in the gated region of a set of high-quality AlGaN/GaN high-electron-mobility transistors (HEMTs). The resistances in the contact, access, and gated regions were extracted from straightforward I-D(V-G) measurements on sets of HEMTs with four different gate-to-drain distances. By correcting for the effects of the contact and access resistances, much more accurate effective mobility curves in the gated region, compared to those reported in the past, have been obtained. The maximum effective mobility in that region has been found to be 1100cm(2)V(-1) s(-1) at carrier density n(s) = 7 x 10(12)cm(-2) at room temperature. We have extracted the mobility curves in a wide range of temperatures (80 to 520 K) and carrier concentrations (up to 1.3 x 10(13)cm(-2)). Our systematic measurements have revealed various dominant scattering mechanisms as the temperature and carrier concentration change. (C) 2016 The Japan Society of Applied Physics</P>

신경망 기반의 동적 파라미터들을 이용한 음성 경계 추출

마창수(Chang-Su Ma),김계영(Gye-Yong Kim),최형일(Hyung-Il Choi) 한국정보과학회 2002 한국정보과학회 학술발표논문집 Vol.29 No.2Ⅱ

본 논문에서는 음성인식 성능을 높이기 위한 기본적 단계인 음성과 비음성 부분의 경계를 추출하는 음성 경계 추출 방법을 제안한다. 음성경제 추출을 위한 특징들로는 시간영역 분할 파라미터인 ZCR, MA를 사용하고 주파수 영역 분할 파라미터로 주파수 대역 파워 에너지 (Frequency band power energy), 포만트 계수 (Formant coefficient)를 사용하였고 각 파라미터들을 이용하여 응성 경계를 결정할 때 경험에 의해 임계치를 결정하는 단점을 보안하기 위해서 신경망을 이용한다. 신경망의 가중치와 임계치들은 지도 학습을 통해 최적화 되고, 학습을 통해 구성된 망을 음성과 비음성의 경계치 구분에 사용한다.

Prevention of Adjacent Segmental Disease after Fusion in Degenerative Spinal Disorder: Correlation between Segmental Lumbar Lordosis Ratio and Pelvic Incidence–Lumbar Lordosis Mismatch for a Minimum 5-Year Follow-up

Whoan Jeang Kim,Chang Hyun Ma,Sang Ha Kim,Yeon Seung Min,Jae Won Lee,Shann Haw Chang,Kyung Hoon Park,Kun Young Park,Dae Gun Song,Won Sik Choy 대한척추외과학회 2019 Asian Spine Journal Vol.13 No.4

Study Design: Retrospective study. Purpose: Associations among risk factors related to adjacent segmental disease (ASD) remain unclear. We evaluated the risk factors and segmental lordosis ratio to prevent ASD developing after lumbar spinal fusion. Overview of Literature: Risk factors related to ASD development are age, sex, obesity, pre-existing degeneration, number of fusion segments, and decreased postoperative lumbar lordosis (LL). However, the associations among these factors are still unclear and should be clearly identified. Methods: We retrospectively reviewed data on 274 patients who underwent lumbar spinal fusion of three segments or below for lumbar degenerative disease from January 2010 to December 2012, with over 5 years of follow-up. Patients with preoperative sagittal vertical axis (SVA) >5 cm were excluded due to sagittal imbalance. A total of 37 patients with ASD and 40 control patients (CTRL) were randomly selected in a similar distribution of matching variables: age, sex, and preoperative degenerative changes. Sex, age, number of fusion segments, radiologic measurements, L4–5–S1/L1–S1 LL ratio, and spinopelvic parameters (pelvic incidence [PI], pelvic tilt [PT], sacral slope [SS], and SVA) were analyzed. Logistic regression was used to analyze the correlation between PI–LL mismatch and L4–5–S1 segmental lordosis rate. Results: No significant difference was found between ASDs and CTRL groups regarding age, sex, number of fusion segments, fusion method, and preoperative and postoperative spinopelvic parameters (PI, SS, PT, and LL). However, regarding the L4–5–S1/L1–S1 lordosis ratio, 50% (p=0.045), 60% (p=0.031), 70% (p=0.042), 80% (p=0.023), and 90% (p=0.023) were statistically significant; <20% (p=0.478), 30% (p=0.223), and 40% (p=0.089) were not statistically significant. In the postoperative PI–LL <10 group, ASD occurred less frequently than in the PI–LL >10 group, and the difference was statistically significant (p=0.048). Conclusions: Patients with a postoperative L4–5–S1/L1–S1 lordosis ratio >50% had less occurrence of ASD. Correcting LL according to PI and physiologic segmental lordosis ratio is important in preventing ASD.

유산균 발효에 의한 사물탕들부터 노다케네틴의 분리 및 함량분석

김동선 ( Dong Seon Kim ),노주환 ( Joo Hwan Roh ),조장원 ( Chang Won Cho ),마진열 ( Jin Yeul Ma ) 대한본초학회 2012 大韓本草學會誌 Vol.27 No.1

Objectives: The purpose of this study was to investigate the changes in the contents of constituents in Samultang and its fermentations with 10 species of lactic acid bacteria. Methods: Ten strains of lactic acid bacteria, Lactobacillus casei, L. acidophilus , L. casei, L. plantarum, L. amylophilus, L. curvatus, L. delbruekil subsp. lactis, L. casei , B. breve, and B. thermophilum, were used for the fermentation of Samultang. The increased and decreased constituents were identified using HPLC/DAD and various liquid chromatographic techniques, and the structure was elucidated using NMR and MS. These compounds were quantitatively analyzed using an HPLC/DAD system. Results: A remarkably increased component was identified to be nodakenetin and a decreased component was determined to be nodakenin. The fermentation of the ten lactic acid bacteria demonstrated that the decomposable rate of these two compounds in fermented Samultang were different. Samultang fermented by L. plantarum showed the most remarkable changes. Conclusion: Nodakenetin was identified as bioconversion component after fermentation and L. plantarum was discovered the best bacteria to increase the component.

Altered Regulation of Renal Acid Base Transporters in Response to Ammonium Chloride Loading in Rats

Kim, Eun-Young,Choi, Joon-Seok,Lee, Ko-Eun,Kim, Chang-Seong,Bae, Eun-Hui,Ma, Seong-Kwon,Kim, Suhn-Hee,Lee, Jong-Un,Kim, Soo-Wan The Korean Society of Pharmacology 2012 The Korean Journal of Physiology & Pharmacology Vol.16 No.2

The role of the kidney in combating metabolic acidosis has been a subject of considerable interest for many years. The present study was aimed to determine whether there is an altered regulation of renal acid base transporters in acute and chronic acid loading. Male Sprague-Dawley rats were used. Metabolic acidosis was induced by administration of $NH_4Cl$ for 2 days (acute) and for 7days (chronic). The serum and urinary pH and bicarbonate were measured. The protein expression of renal acid base transporters [type 3 $Na^+/H^+$ exchanger (NHE3), type 1 $Na^+/{HCO_3}^-$ cotransporter (NBC1), Na-$K^+$ ATPase, $H^+$-ATPase, anion exchanger-1 (AE-1)] was measured by semiquantitative immunoblotting. Serum bicarbonate and pH were decreased in acute acid loading rats compared with controls. Accordingly, urinary pH decreased. The protein expression of NHE3, $H^+$-ATPase, AE-1 and NBC1 was not changed. In chronic acid loading rats, serum bicarbonate and pH were not changed, while urinary pH was decreased compared with controls. The protein expression of NHE3, $H^+$-ATPase was increased in the renal cortex of chronic acid loading rats. These results suggest that unaltered expression of acid transporters combined with acute acid loading may contribute to the development of acidosis. The subsequent increased expression of NHE3, $H^+$-ATPase in the kidney may play a role in promoting acid excretion in the later stage of acid loading, which counteract the development of metabolic acidosis.

항통풍성 약물류가 Milk Xanthine Oxidase 활성에 미치는 영향

마광진,이경태,권창호 한국분자생물학회 1994 분자생물학뉴스 Vol.22 No.-

삼차원 혼합 적재 문제에 대한 발견적 해법

장창식,강맹규 한양대학교 공학기술연구소 1993 공학기술논문집 Vol.2 No.1

Given a case of known dimensions, a collection of rectangular boxes of different size, and number of boxes of each type, the problem is to find suitable positions for placing the boxes in the case in such a way that spaces required can be minimized. You occasionally face this problem at business, shipment or truck cargo area. This paper developes three dimensional space cutting, space packing, space merging techniques. The method proposed is verified superious to any others with comparision.

Zn-Ni 연속경사 합금도금에 관한 연구

안재우,마창익,안종관 대진대학교 1999 大眞論叢 Vol.7 No.-

Electrodeposition experiments of gradually composite alloys were conducted using rotating disc geometry. Effects of rotating speed and potential on the composition of alloys were studied. Mechanical properties and corrosion resistance of the gradually composite alloys were compared with those of the normally deposited alloys. Zinc content of Zn-Ni alloys increased as increasing disc rotation speed and voltage. Corrosion resistance and adhesion of the gradually composite alloys for all the tested alloys were better than the normally deposited ones.

형상인식을 적용한 용접 결함의 특징변수 추출

김재열,마상동,오성민,송경석,김양중,김창현,곽이구 朝鮮大學校 機械技術硏究所 1999 機械技術硏究 Vol.2 No.2

In this study, the researches classifying the natural flaws in welding parts are performed using the signal pattern classification method. For this purpose 500MHz storage digital oscilloscope including FFT function and enveloped waveform generator are used and the signal pattern recognition procedure is made up the digital signal processing, feature extraction, feature selection and classifier design. Specially it is composed with and discussed using the distance classifier is based in euclidean distance the empirical Bayesian classifier. In feature extracting, it is performed using the class-mean scatter criteria. And the signal Pattern classification method is applied to the signal pattern recognition problems of natural flaw that is porosity inclusion, slag inclusion, lack of penetration, lack of fusion. center crack, side crack, toe crack. root crack as the planar and volumetric flaw classification problem. According to this results, if appropriately learned the neural network classifier is better acquire the recognition rate of 86.31% above through it is different a little according to domain extracting the feature and the classifier

태아용 ECMO 시스템 개발

김재열,유신,마상동,김창현 朝鮮大學校 機械技術硏究所 2001 機械技術硏究 Vol.4 No.1

태아를 자궁외에서 인공양수로 충만한 Chamber에 넣고 막형산화기와 체외순환용 회로를 제대동정맥에 연결함으로서 염소태아의 자궁외 생존 모델을 수립하였다. 염소태아의 자궁외 최장 생존시간은 48시간이었으며, 염소태아의 자궁외 생존을 위한 혈류역학적, 혈액화학적 기초자료를 분석하였다. 태아의 자궁외 생존에 필요한 ECMO 순환 혈류량은 223±15.2㎖/min이었으며 태아생존률 및 태아생존시간에 체온, 마취시간, 태아체중 및 수술 숙련도등이 관계가 있었다. 인공양수를 채운 인공자궁 Chamber와 펌프, 막형산화기, 회로등이 연결된 인공 자궁태반의 프로토 타입을 고안 개발함으로서 동물모델에 의한 추가적인 연구를 가능하게 하였고, 합병증의 연구 및 태아영양공급과 발육문제등을 보완연구함으로서 인간에게 인공자궁태반이 실현될 수 있는 기반연구를 수행하였다. The ECMO system using umbilical cord and membrane type oxygenator which was connected with extracorporeal circulation unit was studied for the development of fetus growth model for goat. Maximum survival time of goat fetus was 48hour and its basic data of blood blow dynamics and chemical compositions were analyzed. Average blood rate required for the extracorporeal circulation was 223±15.2 ㎖/min and survival rate and survival time of fetus was deeply related to body temperature, total anesthetized time, fetus weight and skill for the surgery. The newly developed ECMO model for fetus corrected the problem of previously used ECMO that high pressure pump directly delivered to that fetal heart by installing reservoir bag. By applying the result from this new ECMO model. Further reserach will help to apply the system to human.