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물리교육의 효율적인 교수-학습 지도 방안 : 빛 단원을 중심으로 learning methods of physics education
강현식,박승태,양동익 全北大學校 敎育大學院 1983 敎育論叢 Vol.3 No.-
Teaching physics education, various materials have been used. But many kinds of equipments are not sufficient and their operations are very complecate. On the other hand, it takes a lot of time for preparations. The physical experiments should decide the directions of lectures and motivate the learning students. The most remarkable discovery made by physical science is physical phenomena itself. The central problem in teaching physics today is to establish the principles of physics which consist of the basis of all physical phenomena. And the demonstration experiments are used frequently inside and outside the classrooms, and the operations of experiments are convinient to impulse of interests of students. In order to update the teaching and learning method of physics education effectively, we have studied“LIGHT”in high school's physics using improved method by the experiments though the analysis and investigation of the measuring results.
신상훈,송동석,김철훈,황대석,김용덕,김욱규 부산대학교 병원 암연구소 2007 부산대병원학술지 Vol.- No.21
Purpose : The purpose of this study is to investigate temporomandibular joint arthritis that was induced by intra-articular injection of collagenase in rabbits. Material and Methods: In this study, 12 rabbis was used. We injected collagenase on temporomandibular joint of rabbit and observed for six weeks. H-E stain was done. Results : Four weeks later from 2.0 mg collagenase injection, we observe histologic appearance like arthritis. Conclusion : In our study using injection of collagenase in temporomandibular joint of rabbit we produce arthritis on temporomandibular joint of rabbit.
Family of Dual-Input Dual-Buck Inverters Based on Dual-Input Switching Cells
Yang, Fan,Ge, Hongjuan,Yang, Jingfan,Dang, Runyun,Wu, Hongfei The Korean Institute of Power Electronics 2018 JOURNAL OF POWER ELECTRONICS Vol.18 No.4
A family of dual-DC-input (DI) dual-buck inverters (DBIs) is proposed by employing a DI switching cell as the input of traditional DBIs. Three power ports, i.e. a low voltage DC input port, a high voltage DC input port and an AC output port, are provided by the proposed DI-DBIs. A low voltage DC source, whose voltage is lower than the peak amplitude of the AC side voltage, can be directly connected to the DI-DBI. This supplies power to the AC side in single-stage power conversion. When compared with traditional DBI-based two-stage DC/AC power systems, the conversion stages are reduced, and the power rating and power losses of the front-end Boost converter of the DI-DBI are reduced. In addition, five voltage-levels are generated with the help of the two DC input ports, which is a benefit in terms of reducing the voltage stresses and switching losses of switches. The topology derivation method, operation principles, modulation strategy and characteristics of the proposed inverter are analyzed in-depth. Experimental results are provided to verify the effectiveness and feasibility of the proposed DI-DBIs.
Yang, Dang-Wei,Ma, Zhan-Guo,Qi, Fu-Zhou,Gong, Peng,Liu, Dao-Ping,Zhao, Guo-Zhen,Zhang, Ray Ruichong Techno-Press 2017 Geomechanics & engineering Vol.13 No.2
This paper proposes gob-side entry retaining by roof break and filling in thick-layer soft rock conditions based on the thick-layer soft rock roof strata migration law and the demand for non-pillar gob-side entry retaining projects. The functional expressions of main roof subsidence are derived for three break roof direction conditions: lateral deflection toward the roadway, lateral deflection toward the gob and vertically to the roof. These are derived according to the load-bearing boundary conditions of the main roadway roof stratum. It is concluded that the break roof angle is an important factor influencing the stability of gob-side entry retaining surrounding rock. This paper studies the stress distribution characteristics and plastic damage scope of gob-side entry retaining integrated coal seams, as well as the roof strata migration law and the supporting stability of caving structure filled on the break roof layer at the break roof angles of $-5^{\circ}$, $0^{\circ}$, $5^{\circ}$, $10^{\circ}$ and $15^{\circ}$ are studied. The simulation results of numerical analysis indicate that, the stress concentration and plastic damage scope to the sides of gob-side entry retaining integrated coal at the break roof angle of $5^{\circ}$ are reduced and shearing stress concentration of the caving filling body has been eliminated. The disturbance of coal mining to the roadway roof and loss of carrying capacity are mitigated. Field tests have been carried out on air-return roadway 5203 with the break roof angle of $5^{\circ}$. The monitoring indicates that the break roof filling section and compaction section are located at 0-45 m and 45-75 m behind the working face, respectively. The section from 75-100 m tends to be stable.
Family of Dual-Input Dual-Buck Inverters Based on Dual-Input Switching Cells
Fan Yang,Hongjuan Ge,Jingfan Yang,Runyun Dang,Hongfei Wu 전력전자학회 2018 JOURNAL OF POWER ELECTRONICS Vol.18 No.4
A family of dual-DC-input (DI) dual-buck inverters (DBIs) is proposed by employing a DI switching cell as the input of traditional DBIs. Three power ports, i.e. a low voltage DC input port, a high voltage DC input port and an AC output port, are provided by the proposed DI-DBIs. A low voltage DC source, whose voltage is lower than the peak amplitude of the AC side voltage, can be directly connected to the DI-DBI. This supplies power to the AC side in single-stage power conversion. When compared with traditional DBI-based two-stage DC/AC power systems, the conversion stages are reduced, and the power rating and power losses of the front-end Boost converter of the DI-DBI are reduced. In addition, five voltage-levels are generated with the help of the two DC input ports, which is a benefit in terms of reducing the voltage stresses and switching losses of switches. The topology derivation method, operation principles, modulation strategy and characteristics of the proposed inverter are analyzed in-depth. Experimental results are provided to verify the effectiveness and feasibility of the proposed DI-DBIs.
고효율 백색 발광다이오드 구현을 위한 고점도 형광체 정량 토출 공정 연구
양영진(Young-Jin Yang),김형찬(Hyung-Chan Kim),고정범(Jeong-Beom Ko),양봉수(Bong-Su Yang),당현우(Hyun-Woo Dang),도양회(Yang-Hoi Doh),조경호(Kyung-Ho Cho),최경현(Kyung-Hyun Choi) 한국청정기술학회 2014 청정기술 Vol.20 No.2
현재 고효율 백색 발광다이오드(light emitting diode, LED) 구현을 위한 고점도 형광체 토출에 대한 많은 연구가 진행 중이다. 백색 발광다이오드에서 제품성능에 영향을 미칠 수 있어 고점도 형광체의 정량토출은 중요하다. 그러나 기존 연구에서 고점도 형광체 정량토출의 어려움이 있었다. 고점도 형광체의 정량토출을 위해서 본 연구에서는 다양한 점도에서 미세토출이 가능한 정전기력 프린팅 기술을 적용하였다. 전압 변화에 따른 요구 적출형(drop on demand, DOD) 토출 실험을 진행하여 토출 시 노즐의 메니스커스 각도와 토출 도트 직경 사이의 상관관계를 도출하였다. 토출 전압이 증가함에 따라, 토출 메니스커스 각도는 증가하고 토출 도트 직경은 감소하였다. Currently various studies are underway for dispensing high-viscosity phosphor. These studies have reported limitations and challenges in the dispensing process. The discharged amount of phosphor was approximately the same each time which is important for the implementation of high-efficiency white LED technology. This paper present high-viscosity phosphor dispensing process for white LED implementation by using electrostatic printing technology. The voltage controlled DOD (Drop-On-Demand) discharge experiment was studied to determine angle of drop meniscus at nozzle and dot diameter. With increase in Discharge voltage, the discharge angle of meniscus increased while dot diameter decreased. Therefore it can be concluded that we can control the discharge rate by controling the discharge angle of meniscus.
ESD 전극을 이용한 분무코팅 균일도 개선에 관한 연구
당현우(Hyun-Woo Dang),양성욱(Seong-Wook Yang),도양회(Yang-Hoi Doh),최경현(Kyung-Hyun Choi) 한국기계가공학회 2016 한국기계가공학회지 Vol.15 No.2
In this study, experiments are conducted to improve spray coating uniformity by using second and third electrodes based on the electrospray atomization mechanism. The uniformity of fabricated thin films can be improved by adjusting the design of the second electrode. The implementation of the second electrode with an elongated hole and a bending angle of 90° results in highly uniform films. In addition, induced area to substrate is increased by lowering the applied voltage using the third electrode with a round rod shape. A linear correlation between applied voltage and induced area is confirmed. Thin film thickness and surface roughness are measured after the fabrication of thin films through the electrospray process. It is confirmed that a thin film is formed having an average thickness of 273.44 ㎚, a thickness uniformity of less than 10%, and a surface roughness of 3 ㎚.