In the present study, electrospun PAN precursor webs and the stabilized and carbonized nanofiber webs processed under different heat-treatment conditions were characterized by means of weight loss measurement, elemental analysis, scanning electron microscopy (SEM), attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR), differential scanning calorimetry (DSC), thermogravimentric analysis (TGA), and X-ray diffraction (XRD) analysis. The result indicated that stabilization and carbonization processes with different temperatures and heating rates significantly influenced the chemical and morphological characteristics as well as the thermal properties of the stabilized and then subsequently carbonized nanofiber webs from PAN precursor webs. It was noted that the filament diameter and the carbon content of a carbonized nanofiber web as well as its weight change may be effectively monitored by controlling both stabilization and carbonization processes.

3BK21 program for Veterinary Science, College of Veterinary Medicine‘ Seoul National University. Seoul. Korea Human Co1'd blood has been used for the alternatives of bone marrow transplantation for more 10 years. Recently Mesenchymal s tem cell s , ES-like cells and endothelial stem cells has been successfuly isolated from huam co1'd blood Presentl y. it has been reported that a bout 70 incurable ans tractible di sease was possibly cured by umbili cal cord blood-deri ved s tem cells in the clinit;al test s‘ However‘ isolation and expansion of s tem cells from human umbilical cord blood(UCB) have been very difficult and an obstrucle for the clinical use This study showed that effi cient s iolat iona and expans ion of mesenchymal stem cells from UCB Full term UCB samples were obtained from the umbi lical vein after vaginal deli ve ry with the informed consent 0 1' the mothe1' approved by Borame Hospital Institutional Review Broad (IRB). And a lso. t his work was also a pproved by Seoul National University IRB. Recently, we isolated a population of s tem cells from human corcl bloocl (UCB)‘ which expressed embryo stage specific maker. SSEA-4. ancl the multi-potential stem cell marker‘ 。c t4 And we have sucessfully developed culture methods to expand ancl subculture these cells up to 1.000 billion from one single clone. Subsequently. we were a ble to transclifferente theses stem cells into insulin- producing is let- like structures. which co-express in sulin andC-pepticle, adipocyte, neuron‘ bone and cartilage. In acldition. the isola tion rate of MSC from UCB is about 70 % from the cord blood units. This isolation rate were not affected by maternal ages. the sex of baby, isolation time from the deli very. for example. 12 hrs. 24 hrs ‘ even 48 hrs from delivery Taken together. these findings might have a s ignificant potential to aclvance human UCB clerivecl stem- cell -basecl ther apeutics fOI' clinical use in near future

초 록 유리화공정 고온영역에서의 방사성 배기체 유동해석을 해석하기 위하여 상용 수치해석 범용 툴인 FLUENT를 이용하여 적용성을 검토하여 보았다. 수치해석을 통하여 유리화공정 원형설비에 영향을 미치는 인자를 파악하였는데, 저온용응로, 배관냉각기 및 고온필터 등의 세 단계로 나누어 해석을 수행하였다. 저온용융로의 경우 폐기물 처리용량에 따른 해석과 저온용융로 내부 과잉산소 공급 비에 따른 연소지연 가능성에 대한 수치해석을 수행하였다. 배관냉각기의 경우에는 각종 수치 모델 및 외벽 열전달계수를 확보하였으며 또한 방사성 핵종의 거동을 모사할 수 있는 수치적 기업을 검토하였다. 이러한 방법론을 적용하여 핵종의 열교환기 내부에서의 응고 특성에 대하여 고찰하였다. 수평 유입형식의 인입관이 있는 일반적인 형상과 유입구가 필터 내부에 수직으로 있는 고온필터의 수치해석을 통하여 인입관의 위치에 따른 고온필터의 작동 특성을 비교하였다. Appropriate numerical models for the simulation of off-gas flow in hot area of the vitrification plant have been developed in this study. The models have been applied to analyze the effect of design parameters of real plant and numerical analyses have been performed for CCM(Cold Crucible Melter), pipe cooler and HTF(High Temperature Filter). At first, the effect of excess oxygen and the ratio of oxygen distribution on combustion characteristics in the CCM has been studied. Next, solidification behavior of radio nuclide in the pipe cooler has been numerically modeled and scrutinized. Finally, flow pattern in accordance with the location of off-gas entrance of the HTF has been compared.

L2 speakers often encounter difficulties caused by a dual problem both with vocabulary and structure in delivering his or her intended message. This qualitative study reports on how the dual problem involving both lexical and syntactic problems can be managed by employing CSs. The participants were 12 Korean students studying in a university in the USA, whose language proficiency varied from limited to high advanced. For the data, the participants’ natural conversations in various settings were recorded and stimulated recalls were conducted on the recorded conversations. The study presents various CSs for managing dual lexical-syntactic problems (DL-SCSs) identified from an inductive analysis of the data. Based on a taxonomic analysis of the data, this study presents a taxonomy in which various DL-SCSs are organized in multiple levels. In this paper, examples illustrating how participants employed each DL-SCS are also provided. These examples show that L2 speakers employing appropriate DL-SCSs are likely to communicate their intended meaning despite massive dual problems. Based on the findings, this study suggests that L2 speakers should be encouraged to use DL-SCSs.

This study investigated how task involvement should be practiced to fulfill the theoretical assumptions of Task-Based Instruction (TBI). As the task involvement is to be understood as an indispensable component of TBI, how a high degree of task involvement can be secured and exerted in a most effective way was examined. Having analyzed the data obtained from questionnaire, interviews, reflection papers and proficiency tests, the study indicated that customized and timely feedback and comments on the learners’ performances as well as learners’ sense of responsibility were critical if the task involvement leads to desirable learning outcomes. The study also showed that consciousness-raising (CR) task originated from an authentic task was effective enough to help learners acquire linguistic knowledge in a contextual situation. It made suggestions for how to promote task involvement to better implement TBI, through which the learners can improve language proficiency fully taking advantage of their educational and cognitive experiences.

We have calculated the cosmic ray(CR) acceleration at young remnants from Type Ia supernovae expanding into a uniform interstellar medium(ISM). Adopting quasi-parallel magnetic fields, gasdynamic equations and the diffusion convection equation for the particle distribution function are solved in a comoving spherical grid which expands with the shock. Bohm-type diffusion due to self-excited Alfven waves, drift and dissipation of these waves in the precursor and thermal leakage injection were included. With magnetic fields amplified by the CR streaming instability, the particle energy can reach up to 1016Z eV at young supernova remnants(SNRs) of several thousand years old. The fraction of the explosion energy transferred to the CR component asymptotes to 40-50 % by that time. For a typical SNR in a warm ISM, the accelerated CR energy spectrum should exhibit a concave curvature with the power-law slope flattening from 2 to 1.6 at E ≳ 0.1 TeV.