Superconducting MgB2 Wire Drawing Considering Anisotropic Hardening Behavior and Hydrostatic Effect

Young‑Seok Oh,Ho Won Lee,Kook‑Chae Chung,Duck‑Young Hwang,Seong‑Hoon Kang,Jeong Whan Yoon 대한금속·재료학회 2022 METALS AND MATERIALS International Vol.28 No.7

Numerical modeling was conducted to investigate the deformation behavior of powder mixture during multi-pass drawingprocesses for multi-filamentary MgB2wire. A modified Drucker-Prager Cap (DPC) model with an elliptical cap surface usingthe new material characterization method was developed to capture the anisotropic hardening behavior and hydrostatic effectof the powder mixture. A number of uniaxial die compaction, cold isostatic pressing, diametrical compression, and uniaxialcompression tests were conducted using different powder densities to characterize the modified DPC model. A commercialfinite element software ABAQUS with a user subroutine was used to simulate the drawing of the MgB2wire. The densityand area fraction of the powder mixture during the wire-drawing process were verified with experimental results. The differencein packing density at the inner and outer filaments of the MgB2wire was successfully captured by simulation. Inaddition, the effect of the initial packing density on the superconducting properties of MgB2wire was numerically studied. It is shown that the increase in the superconducting area, which results from a high initial packing density, should be moreeffective compared to the increase in the grain connectivity in enhancing the critical current properties for the MgB2wirewhen the final packing density is saturated after a number of drawing processes.

좌심실비후 환자에서 베타차단제의 급중단이 임상증상 및 좌심기능에 미치는 영향

황종현,김영태,배용학,임현주,조용근,채성철,전재은,박의현 慶北大學校 醫科大學 1997 慶北醫大誌 Vol.38 No.1

목적 : 베타 차단제와 칼슘 길항제의 장기투여로 안정상태에 있는 비후형 심근증이나 고혈압성좌심실비후 환자에서 이들 약제를 갑자기 중단하였을 때 혈역학, 심기능 및 임상상에 미치는 영향을 알아보기 위하여 본 연구를 시행하였다. 대상 및 방법 : 경북대학교 병원 순환기내과에서 통원치료중인 비후형 심근중 환자 5명과 심한좌심실비후를 동반한 고혈압 환자 6명(남자 6명, 여자 5명)을 대상으로 장기투여 중이던 베타 차단제와 칼슘 길항제를 최소 5일 중단한 후 임상증상, 혈압 및 심박수의 변동, 그리고 투약중지 전후에 도플러 심초음파도를 기록하여 좌심실내경, 벽두께, 좌심실근량, 구혈율 및 승모판혈류속도곡선의 변화를 관찰하였다. 결과 : 1) 약물치료 중단 후, 베타차단제의 경우 9명 중 6명에서, 그리고 칼슘길항제 및 디소피라미드를 복용하던 각 1명, 도합 7명의 환자에서 심계항진, 호흡곤란의 악화, 흉통이 관찰되었고, 심계항진을 호소한 1예에서는 심방세동이 재발되었다. 2) 혈압, 심박수, 확장말기 및 수축말기 좌심실내경, 심실중격 및 심실후벽 두께, 좌심실근량 및 구혈을 모두는 치료약물 중단 전후에 다소 변화하였으나 유의하지 않았다. 3) E파 최고속도와 E파 시간속도적분은 약물투여 중단 전후에 유의한 변화는 없었으나, A파 최고속도와 A파 시간속도적분은 중단 후에 각각 유의하게 증가하였으며(both P<0.01), E/A 최고속도비와 E/A 시간속도적분비는 각각 유의하게 감소하였다(both P<0.01). 한편, E파 감속시간, 등용이완시간 그리고 A-Ar 간격[A파의 최고점에서 A reversal(Ar)파의 최저점간의 시간] 모두는 중단 후 유의한 변화가 없었다. 1 결론 : 비후형 심근증 이나 고혈압성 좌심실비후 환자에서 장기투여중이던 베타 차단제와 칼슘길항제를 일시적으로 중단하였을 때 임상중상의 악화와 더불어 확장기 기능의 변화를 초래하였다. 따라서 약물치료로 비록 임상적으로 안정상태에 있더라도 치료를 갑자기 중단할 때는 주의해야 할 것으로 생각된다. Objectives : This study was done to evaluate the changes in clinical findings, hemodynamics and cardiac function after abrupt withdrawal of longterm beta-blockers and/or calcium channel blockers in hemodynamically stable patients with hypertrophic cardiomyopathy and left ventricular(LV) hypertrophy associated with hypertension. Methods : Eleven patients with hypertrophic cardiomyopathy(n=5) and LV hypertrophy associated with hypertension(n=6) were studied. Symptom assessment, blood pressure, electrocardiography and echocardiography including pulsed Doppler examination were obtained before and at least 5 days after abrupt cessation of beta-blockers and calcium antagonists. Results : 1) Deterioration in symptoms(i.e. palpitation, aggravation of dyspnea and chest pain) was observed in seven patients after abrupt withdrawal. 2) There were no significant changes in blood pressure, heart rate, end-systolic and end-diastolic LV dimensions, interventricular septal thickness, LV posterior wall thickness, LV mass, and ejection fraction before and after drug withdrawal. 3) Doppler time intervals and E wave peak-velocity and time velocity integral(TVI) were not significantly changed before and after drug withdrawal. But A wave peak-velocity and TVI after abrupt withdrawal were significantly increased(both p<0.01), and E/A peak-velocity ratio and TVI ratio were significantly decreased(both p<0.01). Conclusions : These findings suggest that temporary omission of beta blockers and calcium channel blockers develops deterioration in symptoms and LV diastolic dysfunction in hypertrophic cardiomyopathy and LV hypertrophy associated with hypertension. Physicians should avoid abrupt withdrawal of longterm beta blockers in LV hypertrophy.

Removal of Cochlodinium polykrikoides using a novel material produced from sediment - A field study

Young一Chae Song,S. Sivakumar,Sung-Chung Ko,Eung-Ju Hwang,Qtae Jo 한국항해항만학회 2007 한국항해항만학회 학술대회논문집 Vol.2 No.추계

The present study was conducted in three fields at Namhae to examine the removal efficiency of organic free, heavy metal immobilized sediment on Cochlodinium polykrikoidesand on sea water quality. The present study results concluded that removal efficiency was depends on the initial number of red tide cells. There was no drastic change in the sea water quality after sediment spray. For the comparison of effectiveness of betonite, zeolite and lime were mixed with sediment did not show any marked difference in removal. Finally, the present study evaluated 5Og/m² sediment is Sufficient to remove 100% cells density, even though various environmental factors are interfering the mechanism.

치커리와 쑥갓의 무균자엽절편체 생산 효율 증진

황현정,전혜정,최근원,김영채 경희대학교식량자원개발연구소 2005 硏究論文集 Vol.24 No.-

치커리와 쑥갓에 있어 식물조직배양이나 형질전환 과정에 필요한 무균 절편체를 얻기 위한 적절한 방법을 제안하기 위해 기내 파종을 위한 소독조건과 배지조성 및 종류에 관한 실험들이 실시되었다. 치커리 'Precole'은 10% NaOCl, 15분간, 'Chiavari'는 5% NaOCl, 15분간이 기내파종 시 발아 및 자엽전개를 촉진시키고 오염발생을 억제하는 조건으로 선발되었다. 쑥갓에서는 발아 및 자엽전개율에 있어 NaOCl 처리 간에 차이는 없었지만 10% NaOCl, 30분간 처리에서 가장 낮은 오염율이 관측되었다. 치커리와 쑥갓의 발아와 자엽전개율 모두 인조토양배지의 사용으로 MS 배지에 비해 현저히 향상 되었다. 비록 육안으로는 오염여부를 관측할 수는 없었지만 이들 인조토양배지에서 자란 쑥갓 묘의 자엽을 MS배지에 치상하여 배양 시에는 오염증상이 나타났으며 이들을 NaOCl 1%로 15분간 소독 후 치상한 결과 오염율을 현저히 낮출 수 있었다. Experiments on the sterilization condition and medium composition and type for in vitro sowing were conducted to suggest a proper way to produce enough aseptic explants for tissue culture or transformation study in chicory and garland chrysanthemum. Fifteen minutes soaking treatment with 10% NaOCl for chicory 'Precole' and 15 minutes with 5% NaOCl for chicory 'Chiavari' were selected as proper sterilization conditions to promote in vitro germination and cotyledon expansion and inhibit the seedling contamination from seed itself. In garland chrysanthemum, there was no significant difference in germination and cotyledon expansion ratio among NaOCl treatments, but the lowest seedling contamination ratio was observed by 30 minutes soaking with 10% NaOCl. Both germination and cotyledon expansion ratio in chicory and garland chrysanthemum were significantly increased by using the artificial soil media in contrast to MS media. Although seedling contamination with the artificial soil media could not be observed with bare eyes, cotyledon explants harvested from the plants grown on the media showed some fungal growth when they were placed onto MS media for further culture. However the percentage of the contamination from these explants was dramatically decreased by 15 minutes sterilization with 1% NaOCl.

고온 플라즈마를 이용한 폐기물 용융 소각기술 개발

엄태인,채종성,성지선,전영남,황순모,김영석 한밭대학교 생산기반기술연구소 2004 생산기반기술연구소 논문집 Vol.5 No.1

A high proportion of hazardous (PVC, asbestos, chlorinated solvents) and infection wastes are treated in incinerators, the high temperature and high energy characteristics of plasma may be employed to convert waste materials into inert small volume products and combustible gases, plasma torch melting(PTM) is one of the most widely used tool for the vitrification of wastes. The ash product generated is of low bulk density and may also contain leachable quantities of toxic heavy metal and organic species. Plasma processing is able to treat these ashes, destroying any contained polyaromatic hydrocarbons components. Also we presented a steady three-dimensional model for a plasma melting furnace optimum designed in this study with RNG k-ε model, and its use in characterizing the structure of the flow field, temperature field and reaction field. Among various types of plasma torches, non-transferred hollow cathode type torch is best suited due to its long lifetime, easy power controllability and steady power output. Development of a plasma torch showed the lifetime longer than 300 hours and efficiency better than 65% And the various factors(electrode diameter, cooling flow rate and temperature and gas flow rate affecting the thermal efficiency of the torch) were experimentally evaluated.

Cu-Zn-Al形狀記憶合金의 擬彈性 變形擧動

鄭潾相,朴景采,黃永根 慶北大學校 1986 論文集 Vol.41 No.-

It is generally recognized that both phenomena of the shape memory and pseudoelasticity effects in Cu-based alloys are associated with order structure in parent phase and thermoelastic martensitic transformation. The pseudoelasticity effects is a phenomenon, by which strain is attained through a stress-induced martensitic transformation and such strain is completely recoverable upon unloading, due to the reversible nature of the transformation. In the present work, pseudoelasticity in a Cu-20.80 wt%Zn-6.36 wt% Al shape memory alloy(A_s=252K) has been extensively studied as a function of deformation temperature, grain constraints, cyclic loading and heat treatment, by tensile test and optical microscopy. The results obtained are as follows; At temperature above A,, the stress-induced martensites were formed and the stress needed to induce the martensitic transformation increased with increasing deformation temperature. An important of the grain constraint effect is the grain size/thickness ratio(gs/t), a relaxation of the grain constraints is associated with a decrease in the critical stress needed to induce the martensitic transformation. The critical stress for martensitic transformation decreased with number of cycles in loading-unloading. After 10 cycles, extened cycling did not result in additional changes on stress-strain curve. After low temperature heat treatment (423-573K) in a quenched alloy, the stress needed to induce the martensitic transformation increased due to the stabilization of parent phase.

도금사업장의 작업환경의 유해인자 노출수준에 관한 연구

문덕환,도수영,이채관,황용식,선병관,손병철,김대환,이창희,김휘동,이채언 인제대학교 백병원 2002 仁濟醫學 Vol.23 No.5

Objective : For the purpose of preparing the fundamental data and assessing the status of exposure level of chemical substances and physical agents. Methods and Material : Such as noise, two types of dust, four types of metals, seventeen types of organic solvents, and four types of other materials classified by specific chemical substances in 21 metal product plating factories classified by 28 processes. The author determined exposure level on those hazardous materials from Jan. to Dec. 2001. Results : The results were as follows: 1. The exposure level for noise was exceeded to Threshold Limit Value(TLV) in the process of 6 cases of Machining, 5 and 4 cases of pre and post-buffing, and 6 cases of waterdrop-removing, the mean noise level of all of processes was not exceeded to compliance level. 2. The exposure level for dust was not exceeded to TLV at all. 3. The exposure level for Chromium(Cr) was exceeded to TLV in Chromium plating process, metal exposure level including Zinc(Zn), Manganese(Mn), and Lead(Pb) was not exceeded to TLV. 4. The exposure level of toluene in case of organic solvents was exceeded to TLV in 1 case of finishing/cleaning, coating/developing process, respectively. 5. The exposure level of four types of other materials classified by specific chemical substances were not exceeded to TLV. 6. The exposure level for dust and metal including Zn, Mn, and Pb was decreased in comparison with two results of air monitoring performed. There was no difference of the exposure level for Cr, noise, and four types of other materials classified by specific chemical substances, and the exposure level for organic solvents was slightly increased. 7. The exposure level for noise in factories employing more than 21 workers was higher than that for noise in foadtories employing less than 20 workers. The more workers, the lower exposure level in metal including Zn, Mn. The exposure level for Cr was increasing in factories employing more than 51 workers, and the more workers the lower exposure level in organic solvents. Conclusion : According to above results, this study suggests positive work environment managements in processes exceeding exposure limit value as well as continuously consecutive work environment management in processes not exceeding exposure limit value and revealing no chronological difference of exposure level should be needed.

인유두종 바이러스 양성 및 음성 침윤성 자궁경부암종에서 p53, p21, mdm2 단백의 발현

박인서,한혜승,김태숙,한지영,김준미,주영채,황태숙 대한병리학회 2001 Journal of Pathology and Translational Medicine Vol.35 No.3

순시 공진 전압 합성형 DC-DC 컨버터에 관한 연구

이상호,이봉섭,정도영,황계호,남승식,노채균 嶺南大學校 工業技術硏究所 1998 工業技術硏究所論文集 Vol.26 No.2

This paper describes a DC-DC converter connected two unit inverters, a half-bridge high frequency resonant inverters, at the input with parallel. It estimated characteristics such as the average power, the average output voltage etc, for the design of the device with the normalized parameter values. Also, This paper confirms a rightfulness of circuit analysis by comparing a simulation and experimental results of proposal converter. The proposed paper certified that the theoretical waveforms are equal to the experimental waveforms. In the future, it is expected that proposal converter can be applicated for the system of fixed DCvoltage source.

Poster Presentation : Differential Cell Fates in Response to ROS Stimulation in Cancer Cells and Normal Fibroblast

( Chae Young Hwang ),( Seung Min Lee ),( Ki Sun Kwon ) 한국노년학회 2010 한국노인과학학술단체연합회 국제학술대회 Vol.2010 No.-