Investigation of the Structural, Electrical, and Optical Properties of MnAl2Se4 Layers Grown Using the Hot-Wall Deposition Technique

S. H. You,K. J. Hong,J. W. Jeong,T. S. Jeong,C. J. Youn,J. D. Moon 한국물리학회 2016 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.69 No.4

MnAl2Se4 layers were grown using the hot-wall deposition technique with an attached reservoir tail. Precise control of the vapor pressure in the reservoir was thought to play an important role in the grown of a stoichiometric layer. From the relation between the reciprocal temperature and the carrier concentration, we extracted the dominant trap level as 96.1 meV in the high-temperature region and 13.9 meV in the middle-temperature region. Thus, from a log-log plot between the mobility and the temperature, the mobility showed the different temperature-dependent decreases of the mobility at temperatures above 100 K: T−1/2 in the temperature range of 100 < T < 225 K and T−3/2 in the temperature of T > 225 K. The mobility decreased in proportion to T1 in the low-temperature range of T < 100 K. By analyzing the optical absorption results, the bandgap variation matched Eg(T) = Eg(0) − 3.19 × 10−3 T2/(T + 488) well, where Eg(0) is estimated to be 3.5616 eV. Consequently, low-temperature growth of MnAl2Se4 layers was achieved by using the hot-wall deposition technique.

승화법에 의한 CdS 단결성 성장

정태수,김현숙,유평렬,신영진,신현길,김택성,정철훈,이훈,신영신,강신국,정경수,홍광준 全北大學校 基礎科學硏究所 1994 基礎科學 Vol.16 No.-

수직 2단 전기로를 제작하고 결정성장관에 꼬리관을 연결하여 seed 결정 없이 승화 방법으로 CdS 결정을 성장하였다. 이때 시료부분과 성장부분의 온도차 ΔT가 이론적인 값 14.7℃와 비교해서 실험적으로 얻은 값이 15℃로 아주 일치하는 값을 나타내었다. 이때 꼬리관의 온도를 110℃로 시간당 0.38mm 정도로 빨리 결정성장관을 끌어 올려 결정을 성장하였다. 분말법의 X-선 회절무늬와 Laue 배면 반사법의 Laue 무늬로 부터 성장된 결정이 육방정이고 결정성장관의 길이 방향으로 c축을 갖는 단결정임을 확인하였다. 또한 CdS 단결정은 상온에서 전자 이동도와 운반자 밀도는 각각 316㎠/V·sec와 2.90× 10 exp (16)cm^-3 정도이였다. We has made 2-zone vertical electric furnace and has been grown CdS single crystal by sublimation method in crystal growth tube with tail tube without seed crystal for growth. While it has been growing, temperature difference ΔT of source and growth part has nearly agreed with theoritical value 14.7℃ and experimental value 15℃. Then, crystal of best quality has been grown, when temperature of tail tube has been 110℃, in spite of quickly pulling up crystal growth tube a degree 0.38mm per hour. The grown crystal have had hexagonal structure and single crystal with c-axis to length of crystal growth tube from X-ray diffraction pattern of powder method and Laue pattern of back reflection Laue method. Also, the mobility and carrier density from Hall effect measurement have been 316㎠/V·sec and 2.90× 10 exp (16)cm^-3 at the room temperature, respectively.

광전도체의 CdS 단결정 성장과 물리적 특성

정태수,유평열,신영진,신현길,김택성,정철훈,이훈,신영신,홍광준,유기수 全北大學校 基礎科學硏究所 1994 基礎科學 Vol.16 No.-

승화방법으로 광전도체의 CdS 단결정을 성장하였고 외삽법으로 구한 a_o와 c_o 의 격자상수 값은 각각 4.1318Å과 6.7122Å임을 알았다. Hall 측정값으로 부터 상온에서의 CdS 단결정의 운반자 농도와 이동도는 각각∼10^23m^-3과 2.93×10 exp (-2)㎡/V sec 이였으며 온도에 따른 이동도 변화는 33 K에서 150 K까지는 T^1/2 에 따라 증가하는 경향이 있고 180 K 에서 상온까지는 T^-2에 따라 감소한 경향이 나타났다. 광전류 측정으로 부터 나타난 단파장대의 봉우리는 진성전이에 기인하는 봉우리였으며 이 봉우리의 에너지값은 CdS 광전도체에 에너지 밴드 갭과 동일한 값을 나타냄을 알았다. A CdS single crystal was grown by using sublimation method. Lattice constants, a_o and c_o , obtained by using extrapolation were 4.1318 Å and 6.7122 Å, respectively. The carrier density was∼10^23m^-3 and the mobility was 2.93×10 exp (-2)㎡/V-sec from measured Hall data at room temperature. The mobility has a increasing tendency in proportion to T^1/2 from 33 K to 150 K and a decreasing tendency in proportion to T^-2 from 180 K to room temperature. The short wavelength band peak measured from photocurrent was due to intrinsic transition, and the energy value of this peak was equal to the energy band gap of CdS photoconductor.

풍력 블레이드 복합재의 결함 탐상을 위한 NDE 모니터링기법

임광희(K. H. Im),김우진(W. J. Kim),정예원(Y. W. Jeong),조철현(C. H. Cho),김선규(S. K. Kim),조영태(Y. T. Cho) Korean Society for Precision Engineering 2021 한국정밀공학회 학술발표대회 논문집 Vol.2021 No.11월

Terahertz waves (T-ray) was extensively studied for the nondestructive evaluation of characterization of various and FRP composite materials for a use of wind energy. The composite materials are being utilized on the various areas. Here, T-rays were used to perform NDE when detecting defects in the trailing edge of a wind turbine blade. This study proposed a method to measure a refractive index of a composite, using T-rays (THz) and reviewed the characteristics of the T-ray E-field of a CFRP composite. Particularly, this study produced images to determine defects in the trailing edge of a wind turbine blade and compared and analyzed the images. The TOF of T-ray penetration was measured using a T-ray through-transmission mode to find the following characteristics of the blade. The trailing edge of a nonconductive wind turbine blade could transmit T-rays, enabling the measurement of refractive indices in a through-transmission mode. The effectiveness and limitations of T-ray for the NDE of composites are discussed.

<i>S100A9</i> and <i>EGFR</i> gene signatures predict disease progression in muscle invasive bladder cancer patients after chemotherapy

Kim, W. T.,Kim, J.,Yan, C.,Jeong, P.,Choi, S. Y.,Lee, O. J.,Chae, Y. B.,Yun, S. J.,Lee, S. C.,Kim, W. J. Oxford University Press 2014 Annals of Oncology Vol.25 No.5

<P>In our previous gene expression profile analysis, IL1B, S100A8, S100A9, and EGFR were shown to be important mediators of muscle invasive bladder cancer (MIBC) progression. The aim of the present study was to investigate the ability of these gene signatures to predict disease progression after chemotherapy in patients with locally recurrent or metastatic MIBC. Patients with locally advanced MIBC who received chemotherapy were enrolled. The expression signatures of four genes were measured and carried out further functional analysis to confirm our findings. Two of the four genes, S100A9 and EGFR, were determined to significantly influence disease progression (P = 0.023, 0.045, respectively). Based on a receiver operating characteristic curve, a cut-off value for disease progression was determined. Patients with the good-prognostic signature group had a significantly longer time to progression and cancer-specific survival time than those with the poor-prognostic signature group (P < 0.001, 0.042, respectively). In the multivariate Cox regression analysis, gene signature was the only factor that significantly influenced disease progression [hazard ratio: 4.726, confidence interval: 1.623-13.763, P = 0.004]. In immunohistochemical analysis, S100A9 and EGFR positivity were associated with disease progression after chemotherapy. Protein expression of S100A9/EGFR showed modest correlation with gene expression of S100A9/EGFR (r = 0.395, P = 0.014 and r = 0.453, P = 0.004). Our functional analysis provided the evidence demonstrating that expression of S100A9 and EGFR closely associated chemoresistance, and that inhibition of S100A9 and EGFR may sensitize bladder tumor cells to the cisplatin-based chemotherapy. The S100A9/EGFR level is a novel prognostic marker to predict the chemoresponsiveness of patients with locally recurrent or metastatic MIBC.</P>

Prevalence and molecular characterizations of Toxoplasma gondii and Babesia microti from small mammals captured in Gyeonggi and Gangwon Provinces, Republic of Korea

Hong, S.H.,Lee, S.E.,Jeong, Y.I.,Kim, H.C.,Chong, S.T.,Klein, T.A.,Song, J.W.,Gu, S.H.,Cho, S.H.,Lee, W.J. Elsevier Scientific Pub. Co 2014 Veterinary parasitology Vol.205 No.3

A survey was conducted to determine the distribution and prevalence of Toxoplasma gondii and Babesia microti infections in small mammals captured in Gyeonggi and Gangwon Provinces, Republic of Korea (ROK). The serological prevalence of T. gondii (ELISA) and B. microti (IFAT) was 2.3% (15/667) and 2.1% (14/667), respectively. DNA extracts from small mammal heart tissues were screened by PCR for T. gondii and B. microti targeting regions of the GRA5 gene and the 18S rRNA and β-tubulin genes, respectively. Only 0.17% (1/578) of Apodemus agrarius was positive of T. gondii by PCR, while 0.52% (3/578) was positive of B. microti. All other small mammal species [Micromys minutus (16), Mus musculus (3), Myodes regulus (22), Microtus fortis (6), and Crocidura lasiura (42)] were negative for both T. gondii and B. microti. Based on sequence polymorphism and phylogenetic analysis, T. gondii closely aligned with Type I, a highly virulent strain, while B. microti positive samples closely aligned with US-type B. microti and others observed in the ROK, Russia, and Japan. These results indicate that A. agrarius is a reservoir for both T. gondii and B. microti in the ROK.

Heme oxygenase-1 mediates nicotine- and lipopolysaccharide-induced expression of cyclooxygenase-2 and inducible nitric oxide synthase in human periodontal ligament cells

Pi, S.-H.,Jeong, G.-S.,Oh, H.-W.,Kim, Y.-S.,Pae, H.-O.,Chung, H.-T.,Lee, S.-K.,Kim, E.-C. Blackwell Publishing Ltd 2010 Journal of periodontal research Vol.45 No.2

<P><I>Pi S-H, Jeong G-S, Oh H-W, Kim Y-S, Pae H-O, Chung H-T, Lee S-K, Kim E-C. Heme oxygenase-1 mediates nicotine- and lipopolysaccharide-induced expression of cyclooxygenase-2 and inducible nitric oxide synthase in human periodontal ligament cells. J Periodont Res 2010; 45: 177–183. © 2010 John Wiley & Sons A/S</I></P><P>Background and Objective: </P><P>Although heme oxygenase-1 (HO-1) plays a key role in inflammation, its anti-inflammatory effects and mechanism of action in periodontitis are still unknown. This study aimed to identify the effects of HO-1 on the proinflammatory mediators activated by nicotine and lipopolysaccharide (LPS) stimulation in human periodontal ligament (PDL) cells.</P><P>Material and Methods: </P><P>The production of nitric oxide (NO) and prostaglandin E<SUB>2</SUB> (PGE<SUB>2</SUB>) was evaluated using Griess reagent and an enzyme immunoassay, respectively. The expression of inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2) and HO-1 proteins was evaluated by Western blot analysis.</P><P>Results: </P><P>Lipopolysaccharide and nicotine synergistically induced the production of NO and PGE<SUB>2</SUB> and increased the protein expression of iNOS, COX-2 and HO-1. Treatment with an HO-1 inhibitor and HO-1 small interfering RNAs blocked the LPS- and nicotine-stimulated NO and PGE<SUB>2</SUB> release as well as the expression of iNOS and COX-2.</P><P>Conclusion: </P><P>Our data suggest that the nicotine- and LPS-induced inflammatory effects on PDL cells may act through a novel mechanism involving the action of HO-1. Thus, HO-1 may provide a potential therapeutic target for the treatment of periodontal disease associated with smoking and dental plaque.</P>

이종 마찰용접 강봉재의 기계적 특성(2. PWHT)

권상우(S. W. Kwon),정원택(W. T. Jeong),공유식(Y. S. Kong),김영식(Y. S. Kim),김선진(S. J. Kim) 한국동력기계공학회 2004 한국동력기계공학회 학술대회 논문집 Vol.- No.-

Dissimilar friction welding were produced using 15㎜ diameter solid bar in chrome molybedenum steel(KS SCM440) to carbon steel(KS S45C) to investigate their mechanical properties. The main friction welding parameters were selected to endure good quality welds on the basis of visual examination, tensile tests, Virkers hardness surveys of the bond of area and HAZ and macrostructure investigations. The specimens were tested as-welded and post-weld heat-treated. The tensile strength of the friction welded steel bars was increased up to 100% of the S45C base metal under the condition of all heating time. Optimal welding conditions were n=2,000(rpm), P₁=60(MPa), P₂=100(MPa), t₁=4(s), t₂=5(s) when the total upset length is 5.4(㎜).

DROWSY BEHAVIOR DETECTION BASED ON DRIVING INFORMATION

M. S. WANG,N. T. JEONG,K. S. KIM,S. B. CHOI,S. M. YANG,S. H. YOU,J. H. LEE,서명원 한국자동차공학회 2016 International journal of automotive technology Vol.17 No.1

Drowsy behavior is more likely to occur in sleep-deprived drivers. Individuals’ drowsy behavior detection technology should be developed to prevent drowsiness related crashes. Driving information such as acceleration, steering angle and velocity, and physiological signals of drivers such as electroencephalogram (EEG), and eye tracking are adopted in present drowsy behavior detection technologies. However, it is difficult to measure physiological signal, and eye tracking requires complex experiment equipment. As a result, driving information is adopted for drowsy driving detection. In order to achieve this purpose, driving experiment is performed for obtaining driving information through driving simulator. Moreover, this paper investigates effects of using different input parameter combinations, which is consisted of lateral acceleration, longitudinal acceleration, and steering angles with different time window sizes (i.e. 4 s, 10 s, 20 s, 30 s, 60 s), on drowsy driving detection using random forest algorithm. 20 s-size datasets using parameter combination of accelerations in lateral and longitudinal directions, compared to the other combination cases of driving information such as steering angles combined with lateral and longitudinal acceleration, steering angles only, longitudinal acceleration only, and lateral acceleration only, is considered the most effective information for drivers’ drowsy behavior detection. Moreover, comparing to ANN algorithm, RF algorithm performs better on processing complex input data for drowsy behavior detection. The results, which reveal high accuracy 84.8 % on drowsy driving behavior detection, can be applied on condition of operating real vehicles.

SimulationX 기반 자동차 semi-active 현가장치의 모델 개발 및 특성 해석

정인태(I. T. Jeong),정동석(D. S. Jeong),정원식(W. S. Jeong),이성민(S. M. Lee),유보연(B. Y. Yoo),장대범(D. B. Jang),서영우(Y. W. Seo),한성민(S. M. Han),이석우(S. W. Lee),여현승(H. S. Yeo),류하오(Hao Liu) 유공압건설기계학회 2022 유공압건설기계학회 학술대회논문집 Vol.2022 No.12

The semi-active suspension system controls the damping force of the vehicle damper to simultaneously improve the steering stability (handling) and ride comfort of the vehicle. In order to improve the ride comfort of a passenger car, performance analysis is required through modeling and simulation adaptation of a semi-active suspension system. This study used SimulationX, a commercial multi-domain analysis S/W, and modeling about 1/4 car of the semi-active suspension system. The damping force was controlled through a given performance of the damper. The developed SimulationX-based semi-active suspension system model is prepared for future controller development research.