• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.20 no.7
• /
• pp.2367-2374
• /
• 1996

A generalized Scheil equation for the solute redistribution in the absence of the back diffusion during the dendritic solidification of binary alloys is derived, in which coarsening of the secondary dendrite arms is taken into account. The obtained equation essentially includes the original Scheil equation as a subset. Calculated results for typical cases show that the coarsening affects the microsegregation significantly. The eutectic fraction predicted for coarsening is considerably smaller than that for fixed arm spacing. The most important feature of the present equation in comparison with the Scheil equation lies in the fact that there exists a lower limit of the initial composition below which the eutectic is not formed. Based on the generalized Scheil equation and the lever rule, a new regime map of the eutectic formation on the initial composition-equilibrium partition coefficient plane is proposed. The map consists of three regimes: the eutectic not formed, conditionally formed and unconditionally formed, bounded by the solubility and diffusion controlled limit lines.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.20 no.10
• /
• pp.3361-3370
• /
• 1996

Micro-Macro approach is conducted for the mixture solidification to handle the closely linked phenomena of microscopic solute redistribution and macroscopic solidification behavior. For this purpose, present work combines the efficiency of mixture theory for macro part and the capability of microscopic analysis of two-phase model for micro part. The micro part of present study is verified by comparison with experiment of Al-4.9 mass% Cu alloy. The effect of back diffusion on the macroscopic variables such as temperature and liquid concentration, is appreciable. The effect, however, is considerable on the mixture concentration and eutectic fraction which are indices of macro and micro segregation, respectively. According to the diffusion time, the behavior near the cooling wall where relatively rapid solidification permits short solutal diffusion time, approaches Scheil equation limit and inner part approaches lever rule limit.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.22 no.5
• /
• pp.698-707
• /
• 1998

A simplified model for predicting microsegregation during columnar-dendritic solidification of binary alloys is developed, in which back diffusion, dendrite arm coarsening and dendrite tip undercooling are simultaneously incorporated. The inclusion of tip undercooling is accomplished by modifying the initial conditions of the existing solute diffusion model, in such forms that tip undercooling depresses the beginning of solidification below the liquidus temperature, and that the secondary arm spacing evolves in accordance with the minimum undercooling theory. Sample calculations for the well-known benchmark system show that the present predictions not only consist with the extablished limiting cases, but also agree favorably with the available experimental data within a reasonable tolerance. In particular, a typical decreasing trend in the eutectic fraction at high cooling rates is successfully resolved. Comparison of the individual and combined effects of characteristic parameters in reference with the limiting cases reveals the interactions among parameters. Every parameter plays the role of reducing the eutectic fraction, and the degree of influence depends primarily on the cooling rate. Coarsening enhances the effect of tip undercooling, while suppressing that of back diffusion. A vigorous back diffusion seems to restrain the apperance of the undercooling effect. Overall, each contribution of the three parameters to microsegregation is estimated to be of the same order, which suffices to justify the present study.

• Journal of Korean Medical classics
• /
• v.20 no.2
• /
• pp.269-288
• /
• 2007

"표유부(標幽賦)"포라료침구경락적기본이론화자오유주침법(包羅了鍼灸經絡的基本理論和子午流注鍼法) 유주팔법등침구임상이론(流注八法等鍼灸臨床理論), 역우기송(易于기송), 통과대차(通過對此)"표유부(標幽賦)"급역대주석가대(及歷代注釋家對) "표유부(標幽賦)" 주석적연구(注釋的硏究). 금득출여하결론(今得出如下結論): 1. "표유부(標幽賦)"중출현적두한경적학술사상(中出現的竇漢卿的學術思想), 시재계승(是在계承)"내경(內經)"화(和)"난경(難經)"적침구학(的鍼灸學), 이론적기본상(理論的基本上), 진일보발전이성적(進一步發展而成的). 대후세침구학적발전산생료중요적영향(對後世鍼灸學的發展産生了重要的影響). 2. 유우폐경적경기유운문혈수출(由于肺經的經氣由雲門穴輸出), 연경락순행체표(沿經絡循行體表), 우시사운문혈구유료통경행기적주치작용(于是使雲門穴具有了通經行氣的主治作用), 고이불설'혈출중부'(故而不說'穴出中府'), 이제출'혈출운문'(而提出'穴出雲門'), 저시두한경재침구이론방면적독도지외(抵是竇漢卿在鍼灸理論方面的獨到之外). 3. 소우침구보사(소于鍼灸補瀉), 인위수지보사법적작용중우호흡보사(인위手指補瀉法的作用重于呼吸補瀉), 제시료순(提示了循), 문, 제(堤), 안(按), 탄(彈), 염, 차, 반(盤), 추, 내(內), 동(動), 요(搖), 조(爪), 절적십사종침자보사수법(切的十四종鍼刺보瀉手法). 4. 제출침자전요관찰확인침구유무이상손상(提出鍼刺前要觀察確인鍼具有无이常損상), 시침전요냉침온난(施鍼前要냉鍼온暖), 시침시요예방절침화피부근육적손상(施鍼時要預防折鍼和皮膚筋肉的損傷), 제출좌수당중이다안침혈(提出左手當重而多按鍼穴), 우수경이서서염전자입적수법(右手경而徐徐捻轉자入的手法), 인위사용쌍수진침위호(인위使用쌍手進鍼위好). 5. 호침가관통경락기혈운행적통로(毫鍼可관通經絡氣血運行的通路), 여오행상응(與五行相應), 인이가평오장지한열(因而可平五臟之寒熱), 가조육부지허실(可調六腑之虛實), 유견사부정지공(有견邪扶正之功), 재구침중응용최위광범(在九鍼中응用最위광泛). 6. 제출침자시요관찰본신(提出鍼刺時要관察本神), 대우'본신'구체가간주시환자적'맥기'화'혈기'(對于'本神'具체可看做是患者的'脈氣'和'穴氣'), 종대적방면간가간주시환자적정신(종大的方面看可看做是患者的精神). 7. 제시료참조전후좌우지혈정확취혈적방법(提示了參照前後左右之血正確取穴的方法), 여참조주변경락확정경락적방법(여參照周邊經絡確定經絡的方法), 병강조요준조골도분촌화굴신수족관절적방법취혈재능취혈정확(병强調要遵照骨度分寸和屈伸手足關節的方法取穴才能取穴正確). 8. 소우두면오관(소于頭面五官).인후경항(咽喉頸項).흉복부(胸腹部), 요배부(腰背部), 부인(婦人) 소아(小兒) 사지등질환(四肢等疾患), 개소료침구치료적경험화심득(介沼了療鍼灸治療的經驗和心得), 제시료자오유주축일안시개혈침법여영구팔법등안시취혈침법(提示了子午流注逐日按時開穴鍼法여靈驅八法等按時取穴鍼法), 성위후세각종안시개혈침법적기초(成위後世各種按時開穴鍼法的基초).