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Effects of Substituting B2O3 for P2O5 on the Structures and Properties of V2O5-P2O5 Glass Systems
Kyungseok Han,황차원,Dong Hwan Kim,Donggun Gwoo,Taehee Kim,Wongyu Choi,Kyungbum Kee,김종환,류봉기 대한금속·재료학회 2012 ELECTRONIC MATERIALS LETTERS Vol.8 No.6
V2O5-B2O3-P2O5 glasses with various compositions were prepared using a normal melt quenching technique,and their characteristics and structural properties were investigated using different techniques. Replacement of P2O5 by B2O3 was found to improve the thermal properties, chemical durability, and room-temperature conductivity. The observed variations in the properties may be correlated with changes in the internal glass network as a result of changes in the chemical composition. Vanadium ions are believed to be present in three possible valence states, namely V3+, V4+, and V5+, and the ratios of these states depend on the glass composition. The observed increases in chemical durability and room-temperature conductivity are assumed to be related to increases in the mean crosslinking density, increases in the number of bridging oxygens,and electron hopping between vanadate ions in different valence states.
실시간 시각적 피드백 보행 훈련이 노인들의 보행 안정성에 미치는 영향
( Kyungseok Byun ),( Sooji Han ),( Dawon Bhang ),( Hyundam Seo ),( Hyo Keun Lee ) 한국운동역학회 2020 한국운동역학회지 Vol.30 No.3
Objective: This study aimed to examine the effects of real-time visual feedback gait training on gait stability in older adults. Method: Twelve older adults participated in this study, being divided into 2 groups including a) visual feedback (VF) and b) non-visual feedback (NVF) groups. For 4 weeks, VF performed a treadmill walking training with real-time visual feedback about their postural information while NVF performed a normal treadmill walking training. For evaluations of gait stability, kinematic data of 15-minute treadmill walking were collected from depth-based motion capture system (30 Hz, exbody, Korea). Given that step lengths in both right and left sides were determined based on kinematic data, three variables including step difference, coefficient of variation, approximate entropy were calculated to evaluate gait symmetry, variability and complexity, respectively. Results: For research findings, VF exhibited significant improvements in gait stability after 4- week training in comparison to NVF, particularly in gait symmetry and complexity measures. However, greater improvement in gait variability was observed in NVF than VF. Conclusion: Given that visual feedback walking gives potential effectiveness on gait stability in older adults, gait training with visual feedback may be a robust therapeutic intervention in people with gait disturbances like instability or falls.
자동변속기 차량의 직결영역 변화에 따른 연비 특성에 관한 연구
한창호(Changho Han),김남균(Namkyun Kim),김우석(Wooseok Kim),이종화(Jonghwa Lee),박경석(Kyungseok Park) 한국자동차공학회 2004 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
Recently automatic transmission is controlled by a microcomputer. However it is desirable that expanding application of microcomputer to total controlling of both engine ad transmission to achieve the better fuel economy. As a way to decrease fuel consumption, the lockup-control is paid attention in automatic transmission at high speed. Te expanded lock-up area shows improved fuel consumption up to 2.75% in FTP-75 mode. Above result is accomplished because the fuel economy is improved by preventing the slip of the torque converter and increasing the transmittance efficiency. If the control of fuel-cut is added in the deceleration region, the total fuel economy will be enhanced.
한현상(Hyunsang Han),이동규(Dongkyu Lee),이종화(Jonghwa Lee),박진일(Jinill Park),박경석(Kyungseok Park) 한국자동차공학회 2005 한국자동차공학회 춘 추계 학술대회 논문집 Vol.2005 No.11_1
Fuel economy in a commercial vehicle is different from a passenger car. Therefore, in this paper differences between the two vehicles are described. Specially, it handles about measurement of the accessory traction force, engine friction and injected fuel. Energy consumption on each accessory is calculated quantitatively by measuring energy flow during traveling under practical road. In order to confirm energy flow measurement, engine frictions from engine dynamometer test is compared with measured data. Calculated engine friction using cylinder pressure from engine dynamometer test is equal to measured engine friction that is obtained by subtracting accessory traction force from engine total friction. With the measurement, Energy consumption of every fuel economy factors in a commercial vehicle are measured and analyzed during traveling in certain section of road.
유압 브레이크 내 밸브의 거동이 적용된 휠 압력의 추정에 관한 연구
박기서(Giseo Park),한경석(Kyungseok Han),최세범(Seibum Choi) 한국자동차공학회 2014 한국자동차공학회 학술대회 및 전시회 Vol.2014 No.11
For chassis control of vehicle such as ABS, TCS and ESP, It is important to feedback exact braking torque which is proportional to wheel pressure. However, using wheel pressure sensor requires extra cost and has difficulty in installation. Therefore estimation of wheel pressure using observer algorithm which has compensation for error between measurement and estimated data is proposed in this paper. Braking situation includes conventional brake and brake with valve control. According to each braking situation, wheel pressure observer is operated actively with variable observer gain. This brake based on hydraulic system is possible to execute ABS algorithm. Also, on-off control valves which are economical and robust are used mainly. The simulation has been performed by using CARSIM which is well known as a vehicle dynamic simulator. Then, the result of comparing estimated wheel pressure with actual wheel pressure has been shown.
Relationship between Structure and Optical Properties in the CdO-B2O3-SiO2 Glass System
Taehee Kim,Donggun Gwoo,김종환,Wongyu Choi,Kyungseok Han,Kyungbum Kee,황차원,류봉기 대한금속·재료학회 2012 ELECTRONIC MATERIALS LETTERS Vol.8 No.6
To study the compositional dependence of the optical properties and atomic structure of glasses, the CdOB2O3-SiO2 ternary glasses, which are known as highly photoconductive glasses, have been investigated. The photoconductivity of glasses containing CdO was investigated in a previous study, because of their potential applications in photoelectronic devices. The thermo-mechanical analysis and the Fourier transform infrared (FT-IR) spectra of the glass samples were measured to determine the structural variation of these glasses. Using transmittance measurements, we calculated the optical energy band gap. This paper presents results for control of the optical energy band gap 3.8 ~ 3.2 eV in cadmium-borosilicate glass system while the structural properties undergo monotonic changes.
Power Steering System의 구동력이 차량 모드주행연비에 미치는 영향
김남균(Namkyun Kim),한창호(Changho Han),김우석(Wooseok Kim),이종화(Jonghwa Lee),박진일(Jinil Park),박경석(Kyungseok Park) 한국자동차공학회 2004 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
To improve the vehicle fuel economy, various technologies have been studied. Meanwhile it deteriorates fuel economy that the increased driving torque for Power Steering System (PSS) due to weighted vehicle and widened tire for low speed driving and parking. So the larger driving torque for PSS is, the lower fuel economy is. Therefore, the study about the effect of the driving torque for PSS and the engine total friction must be preceded to improve the vehicle fuel economy. <br/> In this study, a PSS module separated from the vehicle is used to measure the driving torque for PSS with respect to the pressure of PSS. The result shows that the driving torque for PSS was in direct proportion to the pressure of PSS; 3(N-m) driving torque for PSS vs. 10(bar) pressure of PSS, and 8(N-m) vs. 40(bar). In addition, the driving torque and pressure for PSS was measured according to the engine speed in the component test condition which was in the vehicle condition. Measuring the driving torque for PSP in the vehicle condition was established by using the VeFAS which was a fuel economy analyzer developed in our lab and installing PSS By-pass line. The effect of the driving torque for PSS on the vehicle fuel economy was analyzed with FTP-75 cold start mode.