Ni-Zn Ferrite/Rubber복합형 전파흡수체의 정합조건 설계

김한근,사공건,신광호 東亞大學校 1994 東亞論叢 Vol.31 No.1

The demands for microwave absorbing materials and designs are being increased. We have studied about a new design technique to seek for the matching conditions for composite absorbers. The ferrite/rubber composite microwave absorbers were fabricated with Ni-Zn ferrite prepared by coprzcipitation method and silicone rubber. We have figured out the matching conditions(frequency and thickness) through the material constants of the self-maded ferrite/rubber composite absorber by utilizing the matching map and the matching boundary map. We could make a prediction for the matching conditions of ferrite/rubber composite absorber with our developed design technique.

2종의 Ferrite가 혼합된 페라이트/ 고무 복합형 전파흡수체의 전파흡수특성

김한근,이수호,손무헌,박정학,사공 건 東亞大學校 1997 東亞論叢 Vol.34 No.-

In this study, the ferrite/rubber composite microwave absorbers mixed Ni-Zn ferrite and Ni₂Y ferroxplanna were prepared in order to control matching condition. The variation of the material constants(ε*, μ*) and microwave absorbing characteristics were investigated with various ferrite mixing ratio. The material constants of ferrite/rubber composite microwave absorber could be controlled by variation ferrite mixing ratio.

合成溫度에 따른 濕式 Ni-Zn Ferrite 입자의 크기

金漢根,司空鍵 東亞大學校 1991 東亞論叢 Vol.28 No.1

Formation of Ni-Zn ferrite powders by wet direct method and its change of particle size dependent on the calcined temperature of the coprecipitates were examined. The coprecipitates were prepared by adding alkaline solution into the constituent metal ions solution, and subsequent heat treatments. At 150(℃ ), the particles were ultrafine spherical shaped particles of about 500(Å) in diameter and the particle size of Ni-Zn ferrite obtained by the wet direct method could be arranged from 700(Å) to 1450(Å) by changing the calcined temperature(400, 600, 700 and 1,000(℃ )) of the coprecipitates.

韓方藥의 藥理

김공수,유광석,한종현 圓光大學校 韓醫學硏究所 1993 원광한의학 Vol.3 No.1

Western medical science places the highest priority on scientific analysis and research. Therefore, Western medicine has obtained good results by estabilishing specific countermeasures against individual diseases, with causes thoroughly analysed and positively diagnosed. On the other hand, Oriental medical science has been particular about intergrating the part into the whole, in general. The superiority and/or inferiority of one approach over the other cannot be determined by either of the two medical sciences, due to the fundamentally different bases. Therefore, the two medical schools must now be combined, by distinguishing and isolating the respective characteristics in treatment, first seperatly and then combined, during a transition period. If Western medical science may be likened to a piece of brick, as its substance can be easily defined, Oriental medical science may be likened to cement. If one were to build a medical science house for the 21st century, a comfortable house could be built using either to the medical sciences as building material, Western medical science, corresponding to brick, or Oriental medical science, corresponding cement. Bricks are easily dimensioned and standardized, whereas cement is not only fixed in from, but requires a great deal of experience for its successful use. Howerever, both items are essential as building materials. It may be held that we can successfully treat the complicated pathogens of diseases afflicting the aged and chronically ill patients by making full and intelligent use of both medical sciences.

Ferrite/Rubber Composite의 혼합비에 따른 전파흡수 특성

김한근,박상하,사공건 東亞大學校 1992 東亞論叢 Vol.29 No.1

In this paper, the permeability(??), dielectric constants(??) and absorption characteristics of Ferrite/Rubber composites were investigated. The composite specimens were prepared by molding and curing the mixtures of matrix rubber and Ni-Zu ferrite powders which were synthesized by wet-direct method. The permeability(??) of specimen was decreased from 2.58 to 0.7 in the range of 1∼7 (GHz) and kept constant O. .8 at higher than 7(GHz). The higher the frequency was, the less the values of μ, was from 1.57 to 0.03. The optimum thickness of microwave absorber(F/R=4), utilizing the Smith chart, was about 5(mm). The reflection loss was shown over than 20(dB) from 5.5(GHz) to 4.5(GHz) at 5(mm) thickness and relative band width(B/fm) was about 35(%).

전자 레인지용 복합형 전파흡수체에 있어서 첨가물의 효과

김한근,사공건 東亞大學校 1993 東亞論叢 Vol.30 No.1

In this paper, the absorption characteristics of Ni-Zn ferrite/rubber composite with some additives were investigted. The Composite specimens were prepared by molding and curing the mixtures of matrix rubber, Ni-Zn ferrite powders which were synthesized by wet-direct method and some kinds of additives. The matching thickness on Ni-Zn ferrite/rubber composite with additives, such as Carbon(C), Cobalt (Co), Copper-Manganese(CU-Mn) and Cobalt-Copper-Manganese(Co-Cu-Mn), utilizing the Smity Chart were 7.0, 7.7, 7.6 and 8.0(mm), respectively. The reflection lossof the specimens which were added with C, Co, Cu-Mn and Co-Cu-Mn were shown 16, 32, 28 and 37[dB] in the frequency range between 2.28 and 2.6(GHz), and the relative reflection band width(B/f) fo ferrite/rubber composites with additives(Co, Cu-Mn, Co-Cu-Mn) were about 38, 35 and 32[%], respectively.

잇꽃 Carthamin의 초임계 추출 및 농축

이종민,마상동,한태룡,김공환,임상빈,정인식 경희대학교 생명자원과학연구원 1997 遺傳工學論文集 Vol.9 No.-

Supercritical fluids (SCF) are useful substances that are recently used in bioseparation process. Extraction of carthamin from safflower using supercritical carbon dioxide were examined at various conditions of temperature (35∼40℃), pressure (3000∼5000 psi) and CO₂ flow rate (900∼1200 m/hr). SCF was less effective than solvent methods in carthamin extraction from safflower. Concentration of carthamin was 50% more efficent at the use of alginate beads with 35 g cellulose per column loadings compared to the control (15g cellulose per column loadings).

靜止形 3相 無停電 電源 裝置用 電壓源 인버터의 出力 波形 改善

柳喆魯,李公熙,韓宇勇 全北大學校 1994 論文集 Vol.37 No.-

Uninterruptible power supply[UPS] systems are extensively used for electrical support of computers, communications and other critical systems. At present, most of all inverters used in UPS system are voltage source inverter[VSI]. But the output voltage of the UPS must be a sinusoidal wave, therefore a filter consisting of inductors and capacitors eliminates the harmonics involved in the output voltage of VSI. It is important for making UPS more compact to make the filter smaller. For this purpose, the multi step VSI for UPS systems is presented in this paper. The proposed system operates as like 24 and 36 step VSI by adding the tap changing auxiliary circuit which consists of an auto transformer and several switching elements to the double connected 12 step VSI. The basic theories of the proposed inverter system for analyzing the output waveforms are described. And to optimize the effectiveness of the harmonic reduction, the optimum turn ratio and tap changing control angle of auto transformer are decided by simulation and its validity is verified with experiment.

한국인 관상동맥의 변화양상에 대한 형태학적 연구

권태정,이상용,이한영,고영창,권기석,조재홍,김태공,김유훈,조갑래,서중석,이원태 內務部 國立科學搜査硏究所 2001 國立 科學 搜査 硏究所 年報 Vol.33 No.-

폴록사머 및 프로필렌글리콜을 이용한 클로트리마졸 고형 좌제의 물리화학적 특성

현경희,오유경,김정애,공경환,김지현,양준호,배명수,김호동,이종달,장현욱,용철순,최한곤 한국약제학회 2005 Journal of Pharmaceutical Investigation Vol.35 No.2

To develop a clotrimazole-loaded solid suppository with poloxamer and propylene glycol, the melting points of various formulations composed of poloxamer 188 (P 188) and propylene glycol were investigated. The dissolution study of clotrimazole delivered by the suppository composed of P 188 and propylene glycol was performed. The mixtures composed of P 188 and propylene glycol were homogeneous. Propylene glycol affected the melting points of poloxamer mixtures. In particular, the mixture [P 188/propylene glycol (70/30%)] with the melting point of about 32°C was a solid form at room temperature and instantly melted at physiological temperature. Furthermore, propylene glycol affected greatly the dissolution rates of clotrimazole from the suppository. Dissolution mechanism analysis showed the dissolution of clotrimazole was proportional to the time. Our results indicated that the solid suppository with P 188 and propylene glycol would be a candidate of rectal dosage form for clotrimazole.