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박용운(Yong-Un Park),정학균(Hak-Gyun Jeong),조주희(Ju-Hee Cho),소지영(Ji-Yong So),정동화(Dong-hwa Jung),김대경(Dae-Kyong Kim) 한국조명·전기설비학회 2013 조명·전기설비학회논문지 Vol.27 No.8
This paper is development of single-phase brushless DC motor with outer rotor for ventilation fan. Cogging torque causes the noise?vibration to greatest impact on ventilation fan. Asymmetric notches are applied to tapered-teeth for cogging torque reduction of single-phase brushless DC motor. Initial model is notchless and proposed model is applied 2 asymmetric notches. The proposed method is proved motor characteristic through finite element analysis(FEA). Also, experimental results verify that the proposed model considerably reduces cogging torque and have the good sound quality in ventilation system.
조정희,이정학 ( Jung Hee Cho,Chung Hak Lee ) 한국공업화학회 1992 공업화학 Vol.3 No.2
염료속에 함유된 무기염(NaCl, Na_2SO_4)의 선택적 제거를 위해 역확산과 역삼투를 결합한 방법과 nanofiltration(NF)을 각각 이용하였다. 역확산에 의한 염의 제거율은 염의 종류에 따라 1회(one pass)에 1∼30%를 나타냈으며 염과 염료의 분리비는 10∼500의 매우 큰 값을 갖는 반면 염료의 손실율은 0.3% 이하 였다. 염료용액을 순환시킬수록 음이온인 Cl^- 이온의 제거율이 증가하고 양이온인 Na^+ 이온의 제거율이 감소하는 도난투석현상이 관찰되었다. 또한 공급용액의 유속이 염의 제거에 미치는 영향을 살펴보았다. 역확산에 의해 염이 제거된 염료를 평판형 역삼투막을 사용하여 농축하였으며 Cl^- 이온의 배제율을 solution-diffusion 모델식에 적용하였다. 2회의 Diafiltration(DF)을 수행한 NF에서도 역확산에서와 마찬가지로 도난투석에 의해 Cl^- 이온의 배제율 감소와 음배제율을 관찰하였다. 특히 두번째 DF에서 도난투석의 효과는 더욱 크게 나타났다. Studies were carried out on the selective removal of inorganic salts such as NaCl and Na_2SO_4 from dye solution, using counter diffusion-reverse osmosis and nanofiltration, respectively. For the dye solution used in the experiments, 1 to 30% of salts were removed by counter diffusion while the loss of dye molecules was less than 0.3%. The separation factors by one pass operation were 10-500 according to ionic species. In five successive operations, removals of anion(Cl^-) increased but those of cation(Na^+) decreased due to the Donnan effect. Effects of feed flow rate on removal efficiencies of various ions were also observed at constant flow rate of stripping water. Reverse osmosis of desalted dye solution by counter diffusion was conducted to prepare highly concentrated liquid dyes. The rejection efficiency of dye molecules was greater than 99%. For the rejection efficiency of chloride ion, experimental values were compared with theoretical ones based on solution-diffusion model. Two stage diafiltration was performed in nanofiltration. The rejection efficiency of chloride ion was continuously decreased due to the Donnan dialysis and even negative rejection was observed. The Donnan effect was more pronounced in the second diafiltration.
조미영,강승원,임홍규,조성범,채희선,이달주,이정학,이병동 한국수의공중보건학회 2001 예방수의학회지 Vol.25 No.2
To demonstrate the prevalence of Toxocara spp. eggs in public playgrounds in Seoul city, sand samples collected from March to October in 2000 were examined. Of 1,812 sand samples from 302 playgrounds surveyed, Toxocara canis eggs were detected in 38 sands from 22 place(7.3%). Sand samples in public parks were more contaminated (10%) with the eggs than those in apartment complex area(7.1%) and in residential area(6.8%). Toxocara canis eggs were mostly found in sands in the spring and autumn but were not found in summer. To prevent the comtamination of Toxocara spp. eggs in the public places, the control of dogs and cats wandered do out there will be needed.