Characteristic of Hyperfine Magnesioferrite Particles Possessing Shape Anisotropy

Yim, Going,Yim, Chai-Suck 배재대학교 공학연구소 2005 공학논문집 Vol.7 No.1

The ferrimagnetic resonance technique, with the inclusion of shape anisotropy effects, was used to obtain information about the early stages in the precipitation of magnesium ferrite from iron-doped magnesia. The very small magnesioferrite particles were produced by precipitation method from solid solution of iron ion in single crystal magnesia. The temperature dependence of the resonance anisotropy field for a coherent assembly of hyperfine magnesium ferrite precipitates was investigated in the range 100~400K. The results are interpreted in terms of the shape anisotropy of the precipitates.

Hydrothermally-Synthesized 1.1-nm Tobermorite using Natural Zeolite

Going, Y 한국화학공학회 1999 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.37 No.2

Influence of Molecular-Kinetic Resistances on Heat Transfer in Condensation Phenomenon(Ⅰ)

Yim,Going 培材大學校 1996 培材論叢 Vol.1 No.-

상변화에 있어서 분자운동물질이동에 기인한 온도차는 보통 무시되나 수직평판에 대해서 넛셀형 증기응축에서는 이 해석방법을 고려해야 한다. 이러한 현상은 저증기압하에서 중요한 영향을 준다는 것을 계산결과로 알 수 있다. The usually neglected temperature drop due to the molecular-kinetic mass transfer in change of phase is taken into account in this analysis of Nusselt-type condensation of vapors on a flat vertical plate. Calculations show that the phenomenon has a significant influence at low vapor pressures.

Zeolite 를 이용한 폐수중의 중금속이온의 흡착

임굉(Going Yim) 한국물환경학회 1999 한국물환경학회지 Vol.15 No.3

Zeolites are crystalline aluminosilicate minerals that contain alkali and alkaline-earth metals, such as sodium, potassium, and calcium, as well as water, in their structural framework. The framework is porous, enclosing interconnected cavities in which the metal cations and water molecules are contained. The zeolites have reversible hydration properties in addition to their ration exchange properties. The adsorption effect of heavy meal ions - Cu(Ⅱ), Cd(Ⅱ), Ni(Ⅱ), Pb(Ⅱ), and Zn(Ⅱ) - in wastewater on zeolites by batch adsorption process is investigated. Besides the influence of NH₄^+ ion or CN^- ion coexisted with the heavy metal ions in the wastewater was discussed. The amount of adsorbed ions was variable by initial pH and ionic concentration, especially initial pH value of solution had an important effect on the adsorption. In case of low pH solution, e.g. below 3.0, clinoptilolite adsorbed Pb(Ⅱ), Cd(Ⅱ), Cu(Ⅱ), and Zn(Ⅱ) ions but mordenite almost did not adsorb except Pb(Ⅱ) ion. Under the same adsorption conditions, these ions were more adsorbed on clinoptilolite than on mordenite. Adsorptive rate of heavy metal ions creased equally in order of Pb(Ⅱ)>Cd(Ⅱ)>Cu(Ⅱ)>Zn(Ⅱ)>Ni(Ⅱ) ion on mordenite and clinoptilolite. This tendency was interpreted by the fact that the smaller the radius of hydrated metal ion is, the more is the heavy metal ion adsorbed on zeolites. The adsorption rate of heavy metal ions except Pb(Ⅱ) ion decreased in the presence of NH₄^+ ion in the solution. Especially, the absorptivity of Cu(Ⅱ) ion decreased with increasing CN^- ionic concentration due to the formation of complex anion with CN^- ion.

천연 Zeolite를 이용한 1.1-nm Tobermorite의 수열합성

임굉 ( Going Yim ) 한국화학공학회 1999 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.37 No.2

종골 관절내 골절의 전산화 단층촬영에 따른 분류 및 수술적 치료

권굉우(Going-Woo Kwun),김신근(Sin-Kun Kim),이상욱(Sang-Wook Lee),김문호(Moon-Ho Kim) 대한정형외과학회 1994 대한정형외과학회지 Vol.29 No.5

Development of Silica Supports of High Efficiency for Column Liquid Chromatography

Yim,Going 培材大學校 1997 培材論叢 Vol.2 No.-

다공질실리카 구형의 제조에 관한 새로운 절차를 기술하였으며 이것은 좁은 입도 범위에서 미립자를 제조할 수 있고 더욱이 세공구조의 파라미터는 반응조건에 의해서 영향을 받고 제어할 수 있다. 이와같은 방법으로 LC의 여러 다른 형에 대한 고효율의 다공성 실리카 담체를 개발하였다. A new procedure for the preparation of porous silica spheres is described, which enables very small particles with a narrow size range to be prepared. Furthermore, the parameters of the pore structure can easily be influenced and controlled by the reaction conditions. In this way, porous silica supports of high efficiency were developed for the different types of liquid chromatography.

Effect of Dimensional Wall Conduction on Heat Transfer to Slug Flow(Ⅲ)

Yim,Going 培材大學校 1996 培材論叢 Vol.1 No.-

유한차원의 평판을 지나는 슬러그 유동에 대한 열전달 문제를 고찰하였다. 열은 평판의 외부표면에서 기지의 열유속에 의해서나 또는 평판에서 분포된 열용출에 의해서거나 계에 도입된다. 2차원적 열전달의 전도는 평판에서 일어나며 온도분포는 평판과 유체에 있어서 급수전개에 의하여 구할 수 있다. The problem of heat transfer to a slug flow past a flat plate of finite dimensions is considered. Heat is introduced to the system either by means of a known heat flux at the outside surface of the plate or by means of a distributed heat source in the plate. Two dimensional conduction occurs in the plate. The temperature distribution in the plate and fluid is found in terms of a series expansion.

Equations of Motion on Transfer Coefficient in Turbulence(Ⅱ)

Yim,Going 培材大學校 1996 培材論叢 Vol.1 No.-

경계층부근에서 난류 상황을 설명하기 위해 여러 연구자에 의해서 사용된 재생모델들은 확산계수나 열확산도에 대하여 전달계수의 의존성을 부여하고 있다. 본 연구에서는 다수의 유동방식들이 재생모델에 의해서 보완된 이러한 일부분 정보가 유체동력학적인 성질의 정보로 도달할 수 있는 수단으로 제시하였다. 첫 번째의 흐름모양은 고전적 이론에 있어서 응용된것과 유사한 차원해석을 이용하는 것이고 둘째 모양은 유체역학적 불안정성에 근거를 둔 것이며 셋째 흐름모양은 난류의 준안정상태에 있어서 운동방정식의 해에 관하여 가정에 근거를 둔 것이다. 첫째 방식은 고체경계층 부근에서의 물질전달에, 또한 유체경계층 부근에서의 물질전달에 적용하는 것이다. 다른 두가지 흐름 방식들은 수직벽을 따라 움직이는 액체막에 있어서 물질전달의 경우에 적용한 것과 유동층과 벽사이에서의 열전달 경우에 대해서 적용하는 것이다. 물리적 모델해법과 고전적 해법사이의 비교도 또한 포함된다. The renewal models used by several investigators for representing the turbulent process in the vicinity of a boundary give only the dependence of the transfer coefficient on the diffusion coefficient or thermal diffusivity. In this paper a number of ways are suggested by means of which this partial information supplied by renewal models may be completed with information of a hydrodynamic nature. The first one makes use of dimensional considerations similar to those applied in the classical theory ; the second way is based on the instability theory ; and the third way is based on certain assumptions concerning the form of the solutions of the equation of motion in the quasi-steady-state turbulence. The first way is applied to the mass transfer in the vicinity of a solid boundary and also to the mass transfer in the vicinity of a fluid boundary. The other two ways are used for the case of mass transfer in a liquid film moving along a vertical wall and for the case of heat transfer between a fluidized bed and a wall. A comparison between the physical model method and the classical one is also included.

무력증 파행증에서 시행한 동맥재걸술의 결과

김홍진,강만수,권우형,서보양,권굉보 대한혈관외과학회 2000 Vascular Specialist International Vol.16 No.1

Purpose: Traditionally vascular reconstruction has been reserved for patients with limb threatening ischemia. So, the surgery for claudication has been discouraged by the fear of bypass graft failure, limb loss, and significant perioperative complication that may be worse than the natural history of the disease. However, in a minarity of patients with claudication, the symptoms progress and a severe disability can result, which limit normal daily activities. In these patients intervention may be regarded as worthwhile. Methods: To evaluate the benefit or risk of revascularization that performed in patients with disabling or incapacitating intermittent claudication, the clinical data of patients who underwent the revas-cularization for disabling claudication at Yeungnam University hospital were collected and analyzed retrospectively. Results: From January 1990 to June 1999, 98 patients with disabling claudication were performed the surgical or interventional management (13.7% of all lower limb arterial disease registration in our unit). The patients were 93 males and S females ranging from 35 to 76 years of age. The mean age was 59, with the highest mcidence among people in their 50s, followed by those in their 60s and then in their 70s. History of smoking was noted in S2.7% of the cases. The major arterial occlusive site were aortoiliac artery in 42 cases (42.9%), femoral artery in 23 cases (23.5%), iliofemoral artery in 13 cases (13.3%), popliteal artery in 4 cases (4.1%), tibial artery in 5 cases (5.1%) and multi-level occlusion in 11 cases (11.2%). The operative procedures for disabling claudication were bypass graft operation in 70 cases, thromboembolectomy in 5 cases, endarterectomy in 4 cases and percutaneous trawluminal angioplasty (PTA) in 19 cases. Arterial bypass operations were aortobifemoral or aortobioooliteal bvaass in 17 cases. iliofemoral bvoass in 8 cases. femorotnpliteal bypass in 16 cases. femorotibial bypass in 3 cases, popliteotibial bypass in 6 cases, axillobifemoral bypass in 7 cases and femorofemoral bypass in 13 cases. In 98.4% of the operative cases, the early outcome was good with 3+ to 2+ rating according ta Rutherford criteria and cumulative 12, 24, 60-month primary and secondary patency rates were 83,3%, 76.4%, 71.3% and 87.8%, 86.3%, 81.8%. The operative mortality rates were 0% and no limb loss was noted in this series. Conclusion: In summary, arterial reconstruction for disabling claudication is noted as safe and durable procedure in some selective patients. Therefore, surgical intervention are valid treatment option in selected patients with disabling claudication.