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황나경(N. K. Hwang),차민석(M. S. Cha),이대훈(D. H. Lee),김관태(K. T. Kim),이재옥(J. O. Lee),송영훈(Y.-H. Song) 한국연소학회 2008 KOSCOSYMPOSIUM논문집 Vol.- No.-
The reaction mechanism of methane dry reforming has been investigated using an arc-jet reactor. The effects of input power, CO₂ /CH₄ and added O₂ were investigated by product analysis, including CO, H₂, C₂HY and C₃HY as well as CH₄ and CO₂. In the process, input electrical power activated the reactions between CH₄ and CO₂ significantly. The increased feed ratio of the CO₂ to CH₄ in the dry reforming doesn't affect to the CH₄ conversion but increase the selectivity of CO with suppressing the reaction of H₂ generation. Added oxygen can also increase not only CO selectivity but also CH₄ conversion, For more understanding these results. the reaction has been compared with thermo-equilibrium calculation.
소량의 첨가원소가 Strip - Cast Nd - Fe - B 합금의 미세 조직 형성에 미치는 영향
이대훈(D. H. Lee),장태석(T. S. Jang),김동환(D. H. Kim),김승호(Andrew S. Kim) 한국자기학회 2004 韓國磁氣學會誌 Vol.14 No.5
In order to improve dendritic formation of Nd₂Fe₁₄B phase in the strip-cast Nd-Fe-B alloys that are frequently used for production of high energy sintered magnets, effect of small substitutional additives such as Cu (0.3~1.0 at.%) and Co (0.5~1.5 at.%) on the phase formation and microstructures of the strip-cast alloys based on Nd₁₄Fe_(80)B_6 were investigated. As the amount of Cu addition increased, formation of Nd₂Fe₁₄B dendrites along the direction normal to the strip surface was suppressed with the reduction of the strip thickness mainly due to the increase of fluidity of the melt. However, both the dendrites and their <001> preferred orientation along the direction normal to the strip surface were improved with the increase of the strip thickness as the amount of Co addition increased. The dendrites became finer after small amount of Cu or Co was added. While small copper additions tended to stabilize the formation of primary Fe, small cobalt additions suppressed it. When small amount of Zr was added, however, the dendrite structures were totally collapsed with excessive grain growth of Nd₂Fe₁₄B.
Strip - cast 조건이 Nd - Fe - B 합금의 미세조직 형성에 미치는 영향
이대훈(D.H. Lee),장태석(T.S. Jang),김동환(D.H. Kim),김승호(Andrew S. Kim) 한국자기학회 2002 韓國磁氣學會誌 Vol.12 No.1
In order to improve the microstructure of the strip cast Nd-Fe-B alloys that are frequently used for production of high energy sintered magnets, influence of various strip casting conditions on the microstructure and phase formation and distribution were investigated. Nd-Fe-B strips consisting of microstructures suitable for preparation of high energy sintered magnets could be obtained when the wheel speed was below 5 ㎧. The compositional limit that can avoid the crystallization of free iron in the as-cast state was estimated to be Nd₁₄Fe_(79)B_7. Regardless of the compositional variation, <001> preferred orientation of Nd₂Fe₁₄B normal to the strip surface was always occurred below 5 ㎧, which would eventually enhance the grain alignment during pressing the powder under a magnetic field. While the coercivity of the strip cast alloys increased with the increase of the wheel speed, mainly due to the refinement of Nd₂Fe₁₄B grains, it decreased with the reduction of Nd content in the alloy composition as the formation of free iron increased.
전기도금된 Cu-Sn과 Ni preplated frame의 특성 비교
이대훈(D. H. Lee),장태석(T. S. Jang),홍순성(S. S. Hong),이지원(J. W. Lee),양형우(H. W. Yang),한병근(B. K. Hahn) 한국표면공학회 2006 한국표면공학회지 Vol.39 No.6
In order to improve the performance of PPFs (Pre-Plated Frames), a PPF that employed a Cu-Sn alloy instead of conventionally used Ni was developed and then its properties were investigated. It was found that the electoplated Cu-Sn alloy layer was a mixture of uniformly distributed fine crystallites, resulting in better wettability and crack resistance than those of Ni PPF. Moreover, as in Cu/Ni/Pd/Au PPF, migration of copper atoms from the base metal to the top of the Cu/Cu-Sn/Pd/Au PPF surface was not found although the Cu-Sn layer itself contained considerable amount of copper. It was expected that, by using the newly developed Cu-Sn PPF, any possible heat generation and signal interrupt caused by an external electro-magnetic field could be reduced because the Cu-Sn layer was paramagnetic, i.e., nonmagnetic.
이동륜(D. R. Lee),이대훈(D. H. Lee),조성권(S. K. Jo),김관태(K. T. Kim),정은상(E. S. Jung) 대한기계학회 2017 대한기계학회 춘추학술대회 Vol.2017 No.11
Plasma burner can maintain the flame in broad O₂/C ratio so it has been used in many ways. In this work, the characteristics of plasma burner on high speed flow rate have been investigated. The experiment was conducted in different O₂/C ratio. We found that max voltage is proportional to flow rate. In other words, the rotating arc becomes longer as flow rate increases. We found that methane removal rate is inversely proportional to flow rate and proportional to O₂/C ratio. The diameter of pipe can also have effect to methane removal ratio.
Rotating arc plasma를 이용한 암모니아 처리 연구
강희석(H S Kang),김관태(K-T Kim),이대훈(D H Lee),송영훈(Y-H Song),I M Kim 대한기계학회 2012 대한기계학회 춘추학술대회 Vol.2012 No.11
Rotating arc reactors have several potential advantages over typical non-thermal plasmas and arc torches, particularly in terms of the controlled thermal environment and power efficiency. Such reactors exhibit several modes of operation, each of which can be associated with different process efficiencies. Here we investigate the factors controlling the different modes of operation and the efficiency in each mode. We map the conditions required for realizing each mode. Further, we verify our findings in an experiment for NH₃ decomposition. Our results could be used as a guide for the design of apractical and highly efficient rotating arc reactor.