http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
유기산염 열분해법으로 합성한 Cu-Ni-Zn 페라이트분말의 특성과 하소조건
정재우 한국분말야금학회 1995 한국분말재료학회지 (KPMI) Vol.2 No.1
In this study the calcined condition and characteristic of Cu-Ni-Zn ferrite powder were investigated. The Cu-Ni-Zn ferrite powder has been synthesized by the thermal decomposition of the organic acid salt. This process did not require a strict pH control and provided the uniform composition and fine powder with about 0.3 $\mu\textrm{m}$. The XRD diffraction pattern of this powder showed about 50% spinel phase. The optimum calcination was found to be done at $700^{\circ}C$ for one hour. After the calcination, the amount of spinel increased to 90%. The distribution of the particle size showed bimodal peaks, one was about 0.5 $\mu\textrm{m}$ and the other was about 20 $\mu\textrm{m}$. The large particles of 20 $\mu\textrm{m}$ were the agglomeration of fine Particles. The mean Particle size of the powder was about 0.4 $\mu\textrm{m}$. The powder was compacted under 100 MPa pressure and sintered at 1100~ $1250^{\circ}C$ for one hour in air. The density of ferrites specimen was a function of the sintering temperature. The higher the temperature, the denser the ferrite. The maximum relative density of the sintered ferrite was about 93% at $1250^{\circ}C$. The grain size of sintered specimen at $1200^{\circ}C$ was 5 $\mu\textrm{m}$ and homogeneous.
신비탕(神秘湯) 전탕액(煎湯液)이 가토(家兎)의 신장기능(腎臟機能), 혈압(血壓) 및 혈장(血漿) Cortisol농도(濃度)에 미치는 영향(影響)
정재우,한상환,Chung, Jae-Woo,Han, Sang-Whan 대한한방내과학회 1989 大韓韓方內科學會誌 Vol.10 No.1
This study was investigated to clarify the effect of Sin Bee Tang (神秘湯) on the renal function, arterial blood pressure and plasma cortisol. The results obtained were follows; 1. Urine volume and glomerular filtration rate were decreased significantly after Sin Bee Tang water extract, 0.1ml/kg, administration. 2. Glomerular filtration rate, renal plasma flow and urinary excretion of electrolytes were increased significantly after Sin Bee Tang water extract, 0.25ml/kg, administration. 3. Plasma cortisol concentration increased significantly after Sin Bee Tang water extract, 0.25ml/kg, administration. These results suggest that the therapeutic action of Sin Bee Tang for 'Su Chun (水喘)' has a relation with the increase of plasma cortisol and renal hemodynamic effect.
흡기3밸브 실린더 헤드의 흡입 정상유동 특성에 관한 연구
정재우,이기형,김우태,Chung, Jae-Woo,Lee, Ki-Hyung,Kim, Woo-Tae 대한기계학회 2000 大韓機械學會論文集B Vol.24 No.6
Flow patterns and steady flow characteristics of an intake 3valve cylinder head are not obviously declared. Thus, in the study, the characteristics and limitation of intake flow coefficient which applied to multi intake valve engine are introduced. The flow coefficient and tumble characteristics are investigated by means of the steady flow test and flow visualization method. As the results, it is found that the intake flow rate is dominated by effective valve open area. In addition, this paper shows that the mass flow rate of intake 3valve engine is greater than that of intake 2valve engine and tumble flow of intake 3valve engine is superior to that of intake 2valve engine.
2영역 에너지법과 화염 화상 처리법을 이용한 디젤 연소실내 스월 유동 특성에 관한 연구
정재우,이기형,이창식,Chung, Jae-Woo,Lee, Ki-Hyung,Lee, Chang-Sik 대한기계학회 2002 大韓機械學會論文集B Vol.26 No.12
Recently, many researches have been performed to improve the performance of the combustion and emission in a D.I.Diesel engine. And many new techniques have been introduced and developed to reduce NO$_{x}$ and soot exhausted from diesel combustion. Some of these methods have the peculiar injection timing which is not used to traditional timing. To optimize these injection timing, characteristics of swirl flow and interaction of swirl with injection in the diesel engine should be investigated more carefully. Therefore, in this study, 2-zone energy method is adopted for the understanding of swirl flow in condition of moving piston, and then flame visualizations and image process are performed. From these studies, the characteristics of the swirl flow generated by SCV was investigated and the effect of swirl on injection timing was elucidated. As the results, velocity distribution caused by swirl flow increase the space utilization rate of flame plums. And flame plums of weak momentum are remained inside of combustion chamber by the swirl flow.w.
순철분말과 인(P)이 피복된 철분말 소결강의 기계적 성질
정재우 한국분말야금학회 1994 한국분말재료학회지 (KPMI) Vol.1 No.2
The compacts of pure and phosphorus-coated iron powder with 0~0.8%C were sintered at $1100^{\circ}C$ for 40 min. in cracked ammonia gas atmosphere. The tensile and impact strengths were measured and the relationship of the results with carbon content, phosphorus, quenching and tempering was investigated. The results obtained can be summarized as follows : (1) The tensile strength of sintered compacts increased slowly with carbon content. Increase in tensile strength by heat treatment was evident especially in the low carbon specimen. The specimen with phosphorus showed higher strength compared to pure iron compacts value. (2) No inflection point of elasticplastic deformation on stress-strain curve was observed in sintered steel. The elastic modulus of sintered steel had the same tendency as tensile strength. But the elongation showed the opposite tendency. (3) The impact absorption energy of sintered steel without addition of phosphorus decreased successively with carbon content and by quenching and tempering. On the contrary, addition of phosphorus resulted in an increase of the impact absorption energy. Quenching and tempering did not affect the impact energy especially in high carbon content. (4) The main fracture source was pore in specimen and the propagation of crack occured mostly along the grain boundaries. But the intragranular fracture was also observed in high carbon, quenched and tempered specimen, and especially in the specimen with phosphorus.
0.45%인(P)이 피복된 철분말 소결강의 조직 및 열처리
정재우 한국분말야금학회 1994 한국분말재료학회지 (KPMI) Vol.1 No.1
Commercial pure iron powder and iron powder of coated 0.45% phosphorus were mixed with graphite powder in dry mixer to control carbon content from 0 wt% to 0.8 wt%. Mixed powder was pressed in the mould under the pressure of 510 MPa. Compacts were sintered at 118$0^{\circ}C$ for 40 min. in cracked ammonia gaseous atmosphere. Some of these sintered specimens were quenched in oil, and tempered in Ar gas. All of these specimens were investigated for microstructure, density and hardness in relation to coated phosphorus and carbon content. The results obtained were as follows: (1) The microstructure of the sintered speciments revealed that the amount of pearlite was increased with increasing C content but decreased by P-addition. (2) The P-addition affected the microstructure of pores in which the pore shape became round and its mean size was decreased by P-addition. (3) After tempering of sintered specimens the structure of pearlite was changed from fine structure to coarse one in P added specimen. (4) Hardness was higher in P added specimens.