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      • Al-Ce-Ni계 합금의 비정질 형성거동 및 기계적 특성에 관한 연구

        이용호,구연수,이용호 弘益大學校 科學技術硏究所 1994 科學技術硏究論文集 Vol.4 No.-

        Since amorphous alloys have been known to have better mechanical and chemical properties than crystalline alloys of the same composition, a great number of studies on the formation of Al-based amorphous alloys has been carried out actively. However, little has been obtained about the effect of Rare-Earth metal and Transion Metal addition on amorphous phase formed by melt spinning method. The aim of this study is to determine the compositional range of amorphous phase formation, micro structure of melt-spun Al-based amorphous alloys when Ce and Ni alloying elements were added. Al-Ce-Ni ternary alloys with 5.10 at%Ni were chosen in this study. As Ce of Ni contents increased, the width of the X-ray peak of the rapid solidified ribbons increased indicating the formation of amorphous phases. A similar tendency of the compositional dependence were observed in TEM halo pattern analysis.

      • KCI등재

        편광 변조 방법에 의한 자기 Kerr 회전각 및 Faraday 회전각 측정

        이용호,이상수,이용호 한국광학회 1992 한국광학회지 Vol.3 No.2

        In order to measure fine rotation angles by magneto-optic effects of magneto-optical recording thin films, a polarization modulation method is used. In the experiment, the polarization of laser (He-Ne laser) beam is modulated by a Faraday rotator and the amplified modulated signals are selectively detected by phase sensitive detector. The magnetic Kerr rotation and Faraday rotation hysteresis loops are investigated by this method for thermally evaporated amorphous TbFeCo thin films and RF sputtered garnet thin films. Rotation angles about $0.25^{\circ}$ are measured easily from TaFeCo thin films. In the case of longitudinal Kerr rotation, very small rotation angle of $2.5\times10^{-3^\circ}$ is measured with good accuracy of the measurement (about $1\times10^{-3^\circ}$). And it is found that each thin films have the hysteresis curves of high coercivity and good squareness. 광자기 기록 박막의 자기 광학효과에 의한 미소 편광 회전각을 축정하기 위하여 편광 변조 방법을 이용하였다. 편광 변조 방법은 Faraday 회전자로 레이저광의 편광을 변조하고 phase sensitive detection방법을 써서 변조된 신호만을 선택적으로 검출하는 것이다. 본 실험에서는 진공증착법으로 제작된 TbFeCo박막과 RF 스퍼터링으로 제작된 iron garnet 다결정 박막의 자기 Kerr 회전 및 Faraday 회전 이력곡선을 이 방법으로 조사하였다. 그 결과 $0.25^{\circ}$정도의 미소한 회전각을 측정하였으며 특히 longitudinal Kerr 회전의 경우 $2.5\times10^{-3^\circ}$정도의 매우 작은 회전각도 측정할 수 있었다.

      • 전후 핵무기 통제의 법적 평가와 과제

        이용호 嶺南大學校社會科學硏究所 2002 社會科學硏究 Vol.22 No.1

        올해는 일본의 廣島와 長崎에 원자탄이 투하된 후 57년이 되는 해이다. 그간 국제사회는 오랜 세월 동안 핵군비경쟁을 벌이기도 하였고, 다른 한편에서는 그러한 핵무기를 통제하기 위한 다양한 노력도 경주하여 왔다. 그러나 아직까지 핵무기는 인류의 평화와 안전을 파괴하는 거대한 위협요인으로 자리잡고 있다. 따라서 핵무기의 효과적인 통제는 오늘날 인류의 가히 절대적 과제인 것이다. 본 논문에서는, 지난 廣島와 長崎의 재앙이 다시 일어나서는 안 된다라는 전제하에서, 지난 57년간의 핵무기 통제의 노력을 정리하고, 그것을 바탕으로 보다 효과적인 통제방안을 도출하고 있다. 따라서 비핵화지대에 관한 다양한 조약과 제안, 핵무기비확산조약, 핵기술 등의 다자간 수출통제체제인 쟁거위원회(Zangger Committee)와 핵공급국모임(Nuclear Suppliers Group) 등에 관한 다양한 분석을 통해, 현실적으로 가까운 장래에 효과적으로 핵무기의 확산을 방지하는 것이 용이하지 않다고 결론짓고 있다.

      • KCI등재

        저탄소강에서 Strain Aging 에 미치는 Prestrain 의 영향에 관하여

        이용호,조성석,홍종미 대한금속재료학회(대한금속학회) 1976 대한금속·재료학회지 Vol.14 No.2

        0.14% C-steel의 成分偏析과 殘留應力除去를 爲해 900℃-1hr의 燒準熱處理를 한後 prestrain을 0∼14%範圍로 變化시키고 200 및 400℃에서 時效熱處理를 하였을 때 Strain Aging에 미치는 prestrain의 영향을 檢討하였으며, 아울러 應力 21.4 ㎏/㎟, 온도 400℃의 條件下에서 creep 現象에 미치는 prestrain의 영향도 고찰하였다. Prestrain증가와 더불어 降伏强度는 增加하고 時效온도의 效果는 더욱 현저하였다. 또 prestrain增加時 加工硬化指數는 減少하였으며, Creep strain에 미치는 영향은 顯著하며, creep强度는 增加하였다. An attempt was made to explain the effect of prestrain on strain aging in low carbon steel. Carbon steel bar was normalized at 900℃ in order to eliminate the segregation of solute atoms such as C and N and to release the residual stress, and then prestrained in the range of 0% to 14% followed by aging at 200℃ and 400℃. The effect of prestrain on creep strength was also discussed. Yield strength was increased with increasing the prestrain, and the aging was accelerated noticeably with the degree of prestrain by the increase of aging temperature. The work hardening exponent was decreased as the prestrain increases. Creep strength was also increased with increasing the prestrain.

      • 급냉 응고법으로 제조한 Al-Pb, Al-Pb-Sn-Si-Cu 합금 분말 특성에 관한 연구

        池泰求,李龍鎬 弘益大學校 科學技術硏究所 1993 科學技術硏究論文集 Vol.3 No.-

        For development of Al-Pb alloys, a centrifugal atomizing technique was adopted. Al-5,10wt%Pb, Al-8.5wt%Pb-1.5wt%Sn-4wt%Si-(1,3,5)wt%Cu powders were manufactured using centrifugal atomizer. The powders were cylindrical shape and showed bimodal size distribution. The effect of process variables on the dispersion characteristics of lead, tin, silicon and copper in aluminium matrix were investigated. Cooling rate during atomization was estimated from dendrite arm spacing. The estimated cooling rate was 10²-10??K sec.

      • KCI등재
      • 資産評價에 關한 會計學的 硏究

        李容鎬 광주보건대학 1976 論文集 Vol.3 No.-

        Valuaton has long been one of the most important problems in accounting. Much has been discussed about it and various valuation basis and methods have been developed and argued for each in accounting profession. Despite these long- and serious discussion about valuation, the outcome of the accounting measurement process which is supposed to represent fairly the business income and financial position is believed to be far from satisfactory to the users of accounting information. It has once been strongly argued that accounting is basically not the valuation process, and that valuation itself is not a fundamental function in accounting. But different valuation basis or method results in different accounting figures. Thus, valuation, although not a fundamental function, is a very important problem area in accouting. Accounting measures are expressed in monetary terms, they usually understood as something related to the economic value, which in today's monetary economy is measured by-monetary unit. Therefore as we studied chapter 1-0. it seems to be necessary to point out some problems to cost basis theory from this view point of gereral information system. And I sujest some points as follows:. First of all, In calculation structure; The traditional cost basis was helpful in the realization of ' the purposes of system accounting, but now, it is better to substitute it for the current price basis or market price basis, which has many profitable characters necessary for the interested persons to be helped in decision making. The best way, however, should be the multi-dimentional estimation basis which is adopting the advantage from both cost basis and current price basis. Secondly, in the evaluation of assets. It is recommandable to adopt deductive accounting- principle in place of the inductive accounting principle, while the latter has given the importance on the generally accepted or the traditional experimentalism, the former on the theoretical, rational and scientific thinking. Lastly in the choice of the valuation basis: The .choice of valuation basis is basically a selection of a set of assumptions concerning the accounting purpose. Each set of assumptions related to the time of exchange, type of market and form of goods or services exchanged has its own unique meaning, and therefore each valuation basis has its merits depending- on the purposes it is intended to be used for. A valuatin basis cannot serve all the purposes best and accounting cannot satisfactory carry out its objectives with one best valuation basis.

      • 非晶質强磁性體의 磁化特性의 不安定性

        李龍浩 全北大學校 1985 論文集 Vol.27 No.-

        In order to make clear the origins of instabilities of magnetic properties in minor hysteresis loop, two kinds of amorphous soft magnetic alloys are fabricated by single roller quenching method, the one is Fe_75Si_15B_10 of high magnetic induction and large magnetostriction, and the other is Fe_5Co_70Si_15B_10 of high permeability and zero magnetostriction. B-H loops of the samples are measured with newly investigated digital electronic devices with varying temparature, tension and annealing condition. These results are analyzed by the theory developed for crystalline soft magnetic materials. Initial magnetization curve is obtained with new pulse mode technic. The critical point is observed in the curve at which the first Barkhausen jump occurs. By that point critical field Hs and critical flux density Bo are defined. Considering the physical meaning of Bo, the thickness of 180°domain wall δ can be calculated for the first time as 3.4×10exp(-4)cm and 0.88×10exp(-4)cm for Fe_5Co_70Si_15B_10 and Fe_75Si_15B_10 as quenched respectively. δdecreases by applying tension and annealing. These values are good agreement with theoretical values, and very large compared with that of crystalline counterpart. The formula Hs(t)=Hs(t_1)+α(T+T_0) In t/t_1 is obtained, where t_1 and t are the time corapse after demagnetization, α and T_0 are experimental constants and T is temparature in centigrade. Disaccommodation (DA), which is time decrease of initial permeability μ_i after demagnetization, is measured, and the formula μ_i(t)=μ_i(t_1)-m log t is obtained, which is Richter type decaying function. The relation between Hs(t) and μ_i(t) is deduced as Hs(t)=Hs(t_1)D/(D+1)·(logt/t_1)/(logt_2/t_1) provided D is less than 0.3, where D=[μ_i(t_i)-μ_i(∞)]/μ_i(∞), which is fairly good agreement with experiment. To summarize these results, the instabilities of the minor loops of the samples are caused by large domain wall thickness which is based on small anisotropy of amorphous nature and stabilization field built up in the domain wall by induced local anisotropy that is due to large mobilities of constituent atoms with thermal agitation via exess free volume.

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