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생쥐 1-세포기배의 초급속 동결에 있어서 평형 온도와 노출시간의 영향
정덕수,김형국,박인국,Chung, Duk-Soo,Kim, Hyung-Kuk,Park, In-Kook 대한생식의학회 1998 Clinical and Experimental Reproductive Medicine Vol.25 No.3
The present study was to assess the effect of ultrarapid freezing on the development of 1-cell mouse zygote using cryoprotectants, DMSO (dimethyl sulfoxide) or PROH (1,2-propanediol). We investigated the effect of the type and concentration of cryoprotectant, and of the temperature and time of prefreezing equilibration on their capacity to develop to the blastocyst stage in vitro. The concenration, the equilibration temperature, and the exposure time seemed to serve as an important factor in ultrarapid freezing of 1-cell mouse zygotes. In addition to the exposure time and the concentration of cryoprotectant appeared to playa key role in the development of the embryo. In general, the development of the embryo was more effective at $3^{\circ}C$ than $23^{\circ}C$ and 4.5 M than 3 M for 3 to 5 minutes. At $23^{\circ}C$ the development of the embryo was stimulated by DMSO while at $3^{\circ}C$ it was stimulated by PROH. Thus it has been suggested that there exists a correlation between the concentration of cryoprotectants and exposure time in the development of the embryo. In conclusion, we found that for ultrarapid freezing of mouse 1-cell embryos in DMSO, or PROH-based solution, viability shown optimum depending on the cryoprotectant, the concentration of the cryoprotectant and on the temperature and the duration of equilibration.
Indium Tin Oxide (ITO) Coatings Fabricated using Nanoparticle Slurry and Sol
정덕수,윤동헌,김동환,임경란 한국세라믹학회 2011 한국세라믹학회지 Vol.48 No.6
Indium tin oxide (ITO) coatings were made using an ITO slurry and an ITO sol. This was achieved by dispersing nanosized ITO powder in a mixed solvent without any dispersant and developing an adhesive ITO sol from indium acetate and tin tetrachloride in a mixture of DMF and n-butanol. Coating was carried out in one step by spin coating an ITO slurry, which was then followed by an ITO sol over it. Here, the sol penetrates into the nano ITO particle layers to make them adhere to each other as well as to a glass substrate. This is then followed by sintering at 500℃ for 1 h to produce a uniform film consisting of ITO particles of about 50 nm and 10 nm. ITO films were obtained with sheet resistances from 450 to 1500 ohm/□ by varying spin speed and concentration. Transmittance is higher than 90% at 550 nm.
Indium Tin Oxide (ITO) Coatings Fabricated Using Mixed ITO Sols
정덕수,윤동헌,박상환,김창삼 한국세라믹학회 2009 한국세라믹학회지 Vol.46 No.6
ITO films were achieved by sintering at 500~550oC. This was possible by inducing a seeding effect on an ITO sol by producing crystalline ITO nanoparticles in situ during heat treatment. Two kinds of ITO sols (named ITO-A and ITO-B) were prepared at 2.0 wt% from indium acetate and tin(IV) chloride in different mixed solvents. The ITO-A sol showed a high degree of crystallinity of ITO without any detectable SnO2 on XRD at 350℃/1 h, but the ITO-B sol showed a small amount of SnO2 even after annealing at 600℃/1 h. The 10 wt% ITO-A//ITO-B showed the sheet resistance of 3600Ω/□, while the ITO-B sol alone showed 5200 Ω/□ by sintering at 550℃ for 30 min. Processing parameters were studied by TG/DSC, XRD, SEM, sheet resistance, and visible transmittance.
정덕수 대한기계학회 1993 大韓機械學會誌 Vol.33 No.11
소비자는 자동차 에어컨 제작자에게 시원함만을 요구하기보다는 엔진 출력에 따른 주행성, 저 소음 에어컨, 실내 공기의 청정도 관리의 필요성, 편일사시의 느낌이 좋은 에어컨 등의 구체적 이고 수준 높은 요구를 하고 있다. 이러한 요구는 에어컨 제조업체로 하여금 전문화된 고급 인 력과 고도의 기술, 실험 장비, 정밀한 부품생산체제를 갖추지 않으면 안되게 되었다. 이러한 쾌 적성에 대한 소비자의 요구는 점차로 높아져서 차량의 내외기와 차량의 주행정보를 각종센서가 감지하여 인체가 가장 쾌적하게 느끼는 실내를 항상 유지할 수 있는 시스템의 개발을 촉구하고 있다. 현재 업계에서는 지구 환경 보호에 대응하기 위한 신냉매 에어컨 시스템의 개발은 물론 공해 문제로 인하여 새로운 자동차의 등장에 따른 차세대 에어컨 시스템의 개발과 관련된 연구 개발에 활발한 투자가 이루어지고 있다. 이 글에서는 '70년부터 시작된 한국 자동차에어컨의 변 천을 뒤돌아보고, 현재 사용되는 차량용 에어컨 시스템과 앞으로 사용될 차량용 에어컨 시스템이 어떻게 변화할 것인지에 대하여 살펴보고자 한다.
A Simple Way to Prepare Nanosize NiO Powder by Mixing Acidic Ni Compound with Basic Ni Compound
정덕수,윤동헌,박상환,김창삼 한국세라믹학회 2009 한국세라믹학회지 Vol.46 No.6
Nanosize NiO powder was prepared by mixing acidic nickel nitrate with basic nickel carbonate. The particle size and morphology of NiO were mainly governed by the mole ratio of the nitrate to the carbonate. The effects were studied by DSC, XRD, FTIR, and SEM. Heat treatment conditions influence the particle size distribution of produced NiO powder extensively for the case of 3N7C (3 moles of the nitrate and 7 moles of the carbonate) and 4N6C, but only slightly for 1N9C and 2N8C. Uniform pseudospherical NiO particles were obtained in 50~70 nm for 1N9C and 30~60 nm for 2N8C by calcination at 750℃ for 2 h.