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Electrical, Thermal, and Thermoelectric Transport Properties of Se-doped Polycrystalline Re2Te5
Se Woong Lee,Okmin Park,Hyun-Sik Kim,Won-Seon Seo,Sang-il Kim 대한금속·재료학회 2022 대한금속·재료학회지 Vol.60 No.12
Re2Te5 is considered a potential thermoelectric material because of its intrinsically low thermalconductivity, due to its complex crystal structure. Herein, a series of Se-doped Re2Te5 (Re2Te5-xSex, x = 0, 0.2,1, and 2) samples were synthesized, and their electrical and thermal transport properties were investigated. Pure orthorhombic Re2Te5 phases were successfully synthesized without any impurities for all compositions,and the continuous decrease in the calculated lattice parameters confirmed the substitution of Se atoms atthe Te sites. A maximum power factor of 0.135 mW/mK2was achieved for the sample with x = 0.2 at 880 K,mainly due to the increase in carrier concentration and electrical conductivity. The lattice thermalconductivity significantly decreased for all doped samples, which was attributed to the point defect phononscattering caused by Se doping. The thermoelectric figure of merit, zT reached a maximum value of 0.20 at880 K for Re2Te4.8Se0.2 (x = 0.2) sample, which was approximately 22% higher than that of the pristine Re2Te5sample. The weighted mobility, quality factor, and expected zT were calculated to evaluate the optimizationof the power factor and zT.
치과 기공사들에게서 나타나는 호흡기 증상과 이의 관련 요인
김웅철,오세윤,김지환,김진완,이준석,이가영,이세훈,유진호,김태석 高麗大學校 倂設 保健大學 保健科學硏究所 2001 保健科學論集 Vol.27 No.1
This study was carried out to investigate subjective respiratory symptoms and their attributable factors in Korean dental laboratory technicians. A questionnaire was mailed to randomly selected 1,900 dental laboratory technicians. Among them, 1,344 dental technicians completed the questionnaires and returmned them. Validity and reliability tests on the questionnaires were carried out before the main survey. To investigate risk factors on respiratory subjective symptoms, we performed analysis on distribution of characteristics, and then investigated univariate analysis and multiple logistic regression analysis. The prevalence rate of wheezing, cough and phlegm, and dyspnea was 4.8%, 33.9%, 54.9%, respectively. Statistically significant factors inducing subjective respiratory symptoms by multiple logistic regression analysis were sex, smoking, exercise, health examination, work hours a day, investment gas, investment dust, metal fume, resin vapor, and asbestos dust. Considering the results above, it seems that most subjective respiratory symptoms are related with health habits and occupational environmental-related factors. The result, consideration in mind, suggest that health promotion programs for smoking cessation, regular health examination, and physical exercise in health habit, and improvement on casting and resin work in dental technological environment be necessary.
국가 대표급과 제주도 고교 대표급 수영선수들의 그랩 스타트의 운동학적 분석
김철원,김승곤,오만원,임상용,김성찬,이창준,남사웅,이세형,류재청,신석종,김세민 濟州大學敎 體育科學硏究所 1998 체육과학연구 Vol.4 No.-
The purpose of the study was to undertaken to analysis the Grab starting technique between national representive team(3) and Cheju's representive team(3) with 3D cinematography. The conclusions obtained were as follows: Cheju's showed more elapsed time than national representive team on starting block. and more vertical than horizontal direction of COG position, more concentrated vertical velocity & acceleration than forward direction. Therefore It is necessory for cheju's to train balanced trust force in horizontal and vertical direction in grab starting technique.
김세호,윤재웅 대구대학교 산업기술연구소 2014 産業技術硏究 Vol.25 No.1
Weight reduction of the vehicle is strongly enforced globally due to the regulation of the fuel efficiency and emission. In this review, the R&D tends are briefly explained for the application of the high strength steel to vehicle structure for the weight reduction among many techniques. The weight portion of the body in white in the foreign exhibition shows that high strength steels are widely used with the newly developed stamping techniques. This review also illustrate stamping techniques such as hot press forming, roll forming, roll forming, servo-press and drawing process with 1Gpa-steel, which are widely appled to the manufacturing process of high strength auto-parts.
김철원,임상용,김승곤,오만원,김성찬,이창준,남사웅,이세형,류재청 濟州大學敎 體育科學硏究所 1996 체육과학연구 Vol.2 No.-
The study was undertaken to analysis, evaluate, and prescribe the annual effect of training of periodically anaerobic and erobic motor ability for Che-Ju representive team of elementary, middle and high school athletes, first the performance can be obtained when it was prescribed proper training after analysis of physical fitness by each events, second individually fitness scientific analysis. prescription. proper management of athlete will be necessary to apply.
제주 우수 육상경기 선수들의 년중 훈련효과 분석 및 처방
김철원,임상용,김승곤,오만원,김성찬,이창준,남사웅,이세형,류재청 濟州大學敎 體育科學硏究所 1996 체육과학연구 Vol.2 No.-
The study was undertaken to analysis, evaluate, and prescribe t h e annual effect of training of periodically anaerobic and aerobic motor ability for Che-Ju representive team of elementary, middle and high school athletes. first. the performance can be obtained when it was prescribed proper training after analysis of physical fitness by each events. second, individually fitness. scientific analysis. prescription. proper management of athlete will be necessary to apply. In addition to physiology aspect, it is essential to consider sport biomechanics. sport psychology when we prescribe specific events and necessary approach in demension coach-athlete-researcher for individual.
가솔린 기관의 사이클 시뮬레이션에 의한 성능과 배출가스 예측에 관한 연구
金世雄 金烏工科大學校 1988 論文集 Vol.9 No.-
The prediction of performance and exhaust emissions was wade for a spark ignition engine by cycle simulation. Several models were employed which included two-zone, thermodynamic combustion, heat transfers, chemical equilibrium, chemical kinetics for No emission. Predictions were compared with experimental data which was measured for emissions, combustion pressure and engine output. The calculated values of pressure and emissions according to operating conditions showed qualitative agreement with measured data except No concentration.
연료 분사 Pocket이 있는 Gasoline Engine의 성능과 희박 한계
김세웅,김경훈 金烏工科大學校 1993 論文集 Vol.14 No.-
This paper describes the effect of air-assisted fuel injection system(AAI) using compressed air to improve the performance of lean combustion engine. AAI is designed to promote fuel atomization and intake flow. In order to investigate the performance of engine with AAI, experiments are conducted varying to the engine revolution speed, lean air-fuel ratio and intake manifold pressure. Compared with the original engine, the performance of the engine with AAI is improved as the air-fuel mixture becomes leaner or the engine load becomes lower. The decreasing rate of BSFC is proportional to the relative air-fuel ratio, and lean misfire limit extended more than 0.2 relative air-fuel ratio.
공기 보조 분사 장치를 이용한 엔진 성능 향상 및 연비 개선
김세웅,심국상,이근봉 金烏工科大學校 1995 論文集 Vol.16 No.-
This paper describes the improvement of engine performence and fuel consumption through improved combustion formed by the tumble and swirl flows of an in-cylinder fuel-air mixture that uses an air forced fuel injector(AFI) which used compressed air. The AFI is designed to promote fuel atomization and to form uniform fuel-air mixture. In order to make up the tumble and the swirl flows of the in-cylinder mixture, the end of AFI is attached to the tube containing the fuel-air mixture to ensure the adequate flow and to ensure that the remaining kinds of mixture will flow effectively. In order to investigate the improvement of engine performence and fuel consumption, 2 models of tubes which make tumble and swirl flows were utilized. Each model was examined according to engine speed, intake manifold pressure and excess air ratio and compared with a base engine. Compared with the base engine, the results show that the AFI improves the engine performance and the brake specific fuel consumption(BSFC) in all of the engine speeds and the boost pressures at the tumble and the swirlflows. It also decreases exhaust emission of hydrocarbon(HC)