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PWM 방식과 인버터 방식의 압축기를 사용한 시스템 에어컨의 성능평가에 대한 실험적 연구(냉난방 특성)
전용호,김대훈,허삼행,권영철,문제명,홍주태 대한설비공학회 2003 설비공학 논문집 Vol.15 No.9
In the present study, the heating and cooling characteristics of system air-conditioner using a PWM compressor or a BLDC inverter compressor are investigated by the psychometric calorimeter using air enthalpy method. Cooling and heating capacities, power inputs and COPs are measured at the low, moderate, high loads under the cooling and heating standard conditions. At cooling conditions, the capacity of the PWM system is larger than that of the inverter case. Due to large power input, however, low COPs are measured under total load ranges. At heating conditions, the capacity of the PWM method is a little larger than that of the inverter case, except high load range. Since power input is low, large COPs are measured at moderate and high load ranges, which are different from cooling data. This shows that the PW system compared with the inverter case has good energy consumption efficiency at moderate and high load ranges except low load range. And when the system A/C is operated under the cooling and heating standard conditions, COPs are nearly uniform at total load ranges.
서미스터로의 응용을 위한 La0.7Sr0.3MnO3 박막의 구조적, 전기적 특성
임정은,박병준,이삼행,이명규,박주석,김병철,김영곤,이성갑 한국전기전자재료학회 2022 전기전자재료학회논문지 Vol.35 No.5
La0.7Sr0.3MnO3 precursor solution were prepared by a sol-gel method. La0.7Sr0.3MnO3 thin films were fabricated by a spin-coating method on a Pt/Ti/SiO2/Si substrate. Structural and electrical properties with the variation of sintering temperature were measured. All specimens exhibited a polycrystalline orthorhombic crystal structure, and the average thickness of the specimens coated 6 times decreased from about 427 nm to 383 nm as the sintering temperature increased from 740℃ to 830℃. Electrical resistance decreased as the sintering temperature increased. In the La0.7Sr0.3MnO3 thin films sintered at 830℃, electrical resistivity, TCR, B-value, and activation energy were 0.0374 mΩ‧cm, 0.316%/℃, 296 K and 0.023 eV, respectively.
권영철,진의선,허삼행,김대훈,홍주태,문제명 한국에너지학회 2004 에너지공학 Vol.13 No.3
본 연구에서는 용량가변방식을 적용한 PWM 압축기의 냉방운전 시 소비전력 변화 및 성능향상을 조사하기 위해서 기존 및 개선된 압축기의 능력, 소비전력, COP를 측정하여 비교하였다. 압축기의 효율 향상을 위해 무부하 상태에서 압축기 운전콘덴서의 변경, 복수구동부의 교차운전, 그리고 주 전류단에 코일을 적용하여 소비전력의 변화를 측정하였다. 용량가변형인 PWM 압축기는 압축기 능력이 증가함에 따라 소비전력과 COP가 선형적으로 증가하였다. 압축기의 운전 콘덴서를 바꾸어가면서 소비전력을 측정한 경우 소비전력의 최적점이 확인되었다. 한편, 복수 구동부의 적용으로 불필요한 과전압에 의한 소비전력을 감소할 수 있었다.
Structural and Electrical Properties of Nd-Doped (La,Sr)MnO 3 Bulk Ceramics
김창현,이명규,임정은,이삼행,박주석,김병철,이성갑 한국전기전자재료학회 2022 Transactions on Electrical and Electronic Material Vol.23 No.1
(La 0.7−x Nd x Sr 0.3 )MnO 3 (x = 0.15–0.3) specimens were prepared using the mixed oxide method. All specimens showed an orthorhombic crystalline structure and exhibited microstructures with sub-μm sized grains and pores. According to XPS analysis, Mn 2+ , Mn 3+ and Mn 4+ ions peaks corresponded with binding energies of 640.6–640.9 eV, 642.0–642.4 eV, and 643.4–644.1 eV, respectively. Mn ions were predominantly in Mn 2+ and Mn 3+ states. All specimens exhibited a negative temperature coefficient of resistance (NTCR), in which the resistance decreased linearly as the temperature increased. Resistivity increased with the amount of Nd. The 0.3 mol Nd doped LSMO specimen showed 2.85 × 10 4 Ω cm, the highest value of resistance. The 0.2 mol Nd-doped LSMO specimen showed the highest TCR value, which was − 0.36%/°C, and a B 25/65 value of 366 K.
인버터 스크롤 압축기를 사용한 멀티 에어컨의 냉방 특성에 대한 실험적 연구
권영철,고국원,진의선,허삼행,전용호,이영덕,박인규 대한설비공학회 2004 설비공학 논문집 Vol.16 No.4
In the present study, the cooling characteristics of the multi-air conditioner (A/C) using an inverter scroll compressor are experimentally investigated for the number of the indoor units and the operating conditions (20℃, 24℃, 26℃) under the cooling standard conditions by KS C 9306. In the case of the simultaneous operation for 3 indoor units, the cooling capacity, the mass flow rate and the input power have a decreasing trend and COP has an increasing trend, with decreasing the difference in the operating temperature of the indoor unit and the room temperature. In the case of the simultaneous operation for 2 indoor units, the COP of the indoor unit with large cooling capacity is high when the operating temperature is high, but the COP of the indoor unit with low cooling capacity is high when the operating temperature is low. In the case of the single operation for one unit, when the large cooling capacity of the indoor unit is less than 50% the compressor operates at the minimum operation frequency region and the COP decreases.
(La0.7-xCex)Sr0.3MnO3 세라믹스의 구조적, 전기적 특성
인태연,임정은,박병준,이삼행,이명규,박주석,이성갑 한국전기전자재료학회 2023 전기전자재료학회논문지 Vol.36 No.3
La0.7-xCexSr0.3MnO3 specimens were fabricated by a solid state reaction method and structural and electrical properties with variation of Ce4+ contents were measured. All specimens exhibited a polycrystalline rhombohedral crystal structure, and the (110) peaks were shifted to low angle side with increasing the amount of Ce4+ contents. As Ce4+ ions with different ion radii and charges are substituted with La3+ ions, electrical properties are thought to be affected by changes in the double exchange interaction between Mn3+-Mn4+ ions due to distortion of the unit lattice, a decrease in oxygen vacancy concentration, and an increase in lattice defects. Resistivity gradually decrease as the amount of Ce4+ added increased, and negative temperature coefficient of resistance (NTCR) properties were shown in all specimens. In the La0.5Ce0.2Sr0.3MnO3 specimens, electrical resistivity, TCR and B-value were 31.8 Ω-cm, 0.55%/℃ and 605 K, respectively.
MgO 첨가에 따른 La0.7Sr0.3-xMgxMnO3 세라믹스의 구조적, 전기적 특성
김현태,임정은,박병준,이삼행,이명규,박주석,김영곤,이성갑 한국전기전자재료학회 2023 전기전자재료학회논문지 Vol.36 No.3
La0.7Sr0.3-xMgxMnO3 (LSMMO) (x=0.05~0.20) specimens are fabricated by a solid phase sintering method, and the sintering temperature and time are 1,300℃ and 2 hours, respectively. The dependence of the crystalline structure according to the amount of Mg2+ contents is not observed, and all specimens show a polycrystalline rhombohedral crystal structure, the Xray diffraction (110) peaks move to the high angle side with increasing the amount of Mg2+ contents. LSMMO specimens exhibit a granule-shaped microstructure with an average grain size of 1 μm or less. Resistivity gradually decrease as the amount of Mg2+ contents increased. And in the La0.7Sr0.1Mg0.2MnO3 specimen, resistivity and B25/65-value are 36.7 Ω-cm and 394 K at room temperature, respectively. LSMMO specimens show a variable-range hopping (VRH) electrical conduction mechanism, and the negative temperature of coefficient of resistance (NTCR) is approximately 0.37~0.38%/℃.