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고출력 다이오드 레이저를 이용한 SKD11 표면 열처리 특성
최성대,정선환,양승철,김잠규 한국공작기계학회 2007 한국공작기계학회 추계학술대회논문집 Vol.2007 No.-
An experimental investigation with high power diode laser system was carried out to study the effect of surface heat treatment on the SKD11. The surface heat treatment characteristics of the laser beam were evaluated using hardness tests, optical microscopy, X-ray diffraction and energy dispersive X-ray spectroscopy(EDS). Results indicated that the Hardness were changed by beam size, focal length, feed rates. The micro grain structure was observed retained austenite grain at hardened zone and globular cementite grain at fine grain zone and base metal zone by optical microscopy. The intensive X-ray diffraction patterns of (110)-(200)-(211) was detected on the surface and the hardened surface intensity level was bigger than the unhardened surface. The intensive X-ray diffraction patterns of (110)-(200)-(211) was detected hardened surface and the hardened surface distributed plenty of carbon density than metal zone.
재배고들빼기의 화학성분 연구 : Youngia sonchifolia Max
강석환,조규성 한경대학교 2005 論文集 Vol.37 No.-
In this study, chemical compositions of Godulbaegi(leaves and root) were investigated. As for free sugar of the leaves and roots of Godulbaegi, fructose, glucose and sucrose were detected. The total phenolic content was shown higher in the leaves than in the roots. As for amino acid of the leaves of Godulbaegi, 20 kinds amino acids were detected and among them, L-proline and L-glutamic acids were prominent, root of Godulbaegi, 19 kinds amino acids were detected and among them, L-glutamin, L-proline were prominent. As for fatty acid, linolenic acid was prominent in the leaves of Godulbaegi and linoleic acid was prominent in the roots of Godulbaegi. As for vitamin, only the ascorbic acid was detected in the leaves and roots of Godulbaegi and the rest was trace. As for minerals K, Ca, Mg and Na were prominent in the leaves and roots of Godulbaegi.
정선환,최성대,조규열 한국공작기계학회 2006 한국공작기계학회 추계학술대회논문집 Vol.2006 No.-
This study was carried out to minimize the lifting force and to design the slim sized frame of a height adjustment mechanism. This unit is designed for the display devices in order to enhance the ergonomics for effective height adjustment as well as to achieve much slimmer frame for the pedestal. A tolerance analysis of 6 sigma was applied to achieve smooth lift at design stage not to change the tolerance specification of gap several times in a roller type of lifting mechanism at mass production stage. The specification of minimum gap and the target of production yield ratio were agreed with a quality team before tooling. A DFSS simulation on drawings had been done with reasonable tolerance and achievable standard deviation(σ) several times until the target spec of gap and yield ratio was met. Once tolerance and deviation(σ) were fixed tooling start was done successfully. A CAE method was applied to achieve a slim design. Design parameters were frozen when those parameters matched the reference strength data of standard model. Through those tolerance analysis and CAE simulation the number of tool modification was reduced and production yield ratio was raised up without arguing quality specification at production stage in the end.
이온교환법에 의한 탈질소 공정개발의 기초연구 (Ⅲ) : 희분식 반응기에서의 반응속도론 A kinetic study in the batch reactor
채용곤,이동환,김승일,윤태경,홍성수,이민규 한국환경과학회 2000 한국환경과학회지 Vol.9 No.2
A kinetic study for anion exchange was performed for commercially available Cl^- type anion exchange resin in use to remove nitrate in water. The obtained results from the batch reactor were applied to the Langmuir and Freundlich models. The constants for Langmuir model were q_max=29.82 and b=0.202, and for Freundlich model were K=5.509 and n=1.772. Langmuir model showed better fit than Frendlich model for the experimental results. Ion exchange reaction rate was also calculated and the approximate first-order reaction, rate constant k_1 was 0.16 L/㎎·hr. Effective diffusion coefficient was obtained in the range from 9.67×10 exp (-8) to 1.67×10 exp (-6) ㎠/sec for initial concentration change, and from 6.09×10 exp (-7) to 3.98×10 exp (-6) ㎠/sec for reaction temperature change. Activation energy during the diffusion was calculated as 36 ㎉/㏖.
김환태(Hwan Tae Kim),신형규(Hyoung Gyu Shin),표지수(Ji Soo Pyo),김규환(Gyu Hwan Kim),류승환(Seong Hwan Ryoo),이상혁(Sang Hyuk Lee),설상영(Sang Yung Seol),정정명(Jung Myung Chung),최하진(Ha Jin Choi) 대한소화기학회 1994 대한소화기학회지 Vol.26 No.4
The multiple gastric cancer have several clinicopathological characteristics which differ from those of patients with solitary cancer,' in particular, elderly men had a relatively high in- cidence of multiple cancer and early cancer of the elevated, well differentiated type was most common. A careful preoperative evaluation with both radiography and endoscopy enables de- tection of about 70% of synchronous EGC, and perhaps increased awareness of this phenome- non can lead to better results. We reported on a case of synchronous EGC type I and Iia origi- nating from lower body and antrurn.(Korean J Gastroenterol 1994; 26: 737 741)
hcp-Mg 입자분산형 Mg-Zn-Ce계 비정질합금의 제조와 기계적 성질
Kim, Seong-Gyu,Park, Heung-Il,Kim, U-Yeol,Jo, Seong-Myeong,Kim, Yeong-Hwan,Inoue, A.,Masumoto, T. 한국재료학회 1994 한국재료학회지 Vol.4 No.8
Mg-Zn-Ce계 합금에서 비정질 단상 및 hcp-Mg입자분산형 비정질합금이 20-40%, Zn, 0-10%Ce과 5-20%Zn, 0-5%Ce 의 조성범위에서 각각 생성되었다. 초미세 hcp-Mg입자분산형 $Mg_{85}Zn_{12}Ce_{3}$비정질합금은 급속응고 또는 급속응고리본의 열처리에 의해 Mg입자의 입경을 4-20nm의 범위로 조절할 수 있었으며, 이 범위에서는 밀착굽힘이 가능할 만큼 충분한 인성을 가지고 있었다. 이 합금의 최대인장강도($\sigma_{B}$)와 파단 연신율($\varepsilon_{f}$)은 hcp-Mg입자의 체적분율에 따라서 670-930MPa, 5.2-2.0%의 범위였으며, 최대 비강도($\sigma_{B}$밀도 =$\sigma_{s}$)는 $3.6 \times 10^5N \cdot m/kg$에 달하였다. 이와 같이 Mg입자분산형 비정질 합금의($\sigma_{B}$), ($\sigma_{s}$)그리고 $\varepsilon_{f}$의 최대치가 Mg-Zn-Ce계 비정질합금(690MPa, $2.5 \times 10^5N \cdot m/kg$, 2.5%)보다 월등하게 높다는 것은 주목할 만 하다. 복합상 조직이 형성됨으로서 기계적 강도가 증가하는 것은 동일 조성의 비정질상보다 강한 hcp과포화 고용체의 분산강화에 기인하는 것이라고 고찰되었다. An amorphous single phase and coexistent amorphous and hcp-Mg phases in Mg-Zn-Ce system were found to form in the composition ranges of 20 to 40% Zn, 0 to 10% Ce and 5 to 20% Zn, 0 to 5% Ce, respectively. A $Mg_{85}Zn_{12}Ce_{3}$ amorphous alloy containing nanoscale hcp-Mg particles was found to form either by melt spinning or by heat treatment of melt -spun ribbon. The particle size of the hcp-Mg phase can be controlled in the range of 4 to 20 nm. The mixed phase alloy prepared thus has a good bending ductility and exhibits high ultimate tensile strength($\sigma_{B}$) ranging from 670 to 930 MPa and fracture elongation($\varepsilon_{f}$) of 5.2 to 2.0%. The highest specific strength($\sigma_{B}$/density =$\sigma_{s}$)$3.6 \times 10^5N \cdot m/kg$. It should be noted that the highest values of flB, US and ?1 are considerably higher than those (690MPa,$2.5 \times 10^5N \cdot m/kg$and 2.5%) for amorphous Mg-Zn-Ce alloys. The increase of the mechanical strengths by the formation of the mixed phase structure is presumably due to a dispersion hardening of the hcp supersaturated solution which has the hardness higher than that of the amorphous phase with the same composition.
Genetic Diversity and Relationships of Korean Chicken Breeds Based on 30 Microsatellite Markers
Suh, Sangwon,Sharma, Aditi,Lee, Seunghwan,Cho, Chang-Yeon,Kim, Jae-Hwan,Choi, Seong-Bok,Kim, Hyun,Seong, Hwan-Hoo,Yeon, Seong-Hum,Kim, Dong-Hun,Ko, Yeoung-Gyu Asian Australasian Association of Animal Productio 2014 Animal Bioscience Vol.27 No.10
The effective management of endangered animal genetic resources is one of the most important concerns of modern breeding. Evaluation of genetic diversity and relationship of local breeds is an important factor towards the identification of unique and valuable genetic resources. This study aimed to analyze the genetic diversity and population structure of six Korean native chicken breeds (n = 300), which were compared with three imported breeds in Korea (n = 150). For the analysis of genetic diversity, 30 microsatellite markers from FAO/ISAG recommended diversity panel or previously reported microsatellite markers were used. The number of alleles ranged from 2 to 15 per locus, with a mean of 8.13. The average observed heterozygosity within native breeds varied between 0.46 and 0.59. The overall heterozygote deficiency ($F_{IT}$) in native chicken was $0.234{\pm}0.025$. Over 30.7% of $F_{IT}$ was contributed by within-population deficiency ($F_{IS}$). Bayesian clustering analysis, using the STRUCTURE software suggested 9 clusters. This study may provide the background for future studies to identify the genetic uniqueness of the Korean native chicken breeds.