• Journal of the Korean Institute of Telematics and Electronics A
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• v.33A no.11
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• pp.105-111
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• 1996

We have invetigated the characteristics of thermal instability of Co-silicides annealed at 850$^{\circ}$C ~ 1000$^{\circ}$C for 10~90 minutes in a furance with N$_{2}$ ambient. In our experiments, Co-silicides and Co/Ti bilayer silicides were formed by depositing (Co, Ti) films on the clean Si substrates in an E-beam evaporator and performing the RTA annelaing. The sheet resistances of Co-silicides formed form Co exhibited the nearly constant value under the post-annealing time above 900$^{\circ}$C showing the increase of 30% and 60% under the conditions annealed at 900$^{\circ}$C and 1000$^{\circ}$C for 30minutes. On the other hand, there were no remarkable changes in the sheet resistance sof Co-silicides formed form Co/Ti bilayer under the post-annealing conditons below 1000$^{\circ}$C.

• Journal of Ocean Engineering and Technology
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• v.12 no.3 s.29
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• pp.60-67
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• 1998

In this study, the J-Resistance Curve and material tearing modulus of SA508-C3 steel, which is one of the used nuclear pressure vessel steel, are measured ar room temperature, $200^{circ}C$ and $300^{circ}C$ according to load ratio analysis and ASTM E813, ASTM E1152, respectively. It is observed that J-R curve and Tmat value decrease as the temperature level increase. Applicability of $T_j$ proposed by Paris et al as instability parameter for ductile material is investigated. It is concluded that results are the $T_j$ parameter may be used as a crack instability parameter.

• Proceedings of the KSME Conference
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• 2000.11a
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• pp.328-332
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• 2000

Following the method described in ASTM E1737, J resistance curves are measured for Cr-Mo steel SA387, and Cr steel A240 which are used as piping materials in nuclear industry. Crack driving force diagrams are generated in order to find out instability points in crack growth. The $J_{appl}$ curves, which are used in the crack driving force diagram, are obtained from EPRI J estimation method and the finite element analysis. Crack growth instability points are plotted in load-crack length plane and the results are discussed.

• Journal of Sensor Science and Technology
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• v.22 no.6
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• pp.415-420
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• 2013

Calibration capabilities for thermometer calibration by comparison method were assessed using high-precision industrial platinum resistance thermometers (IPRT). It was found in the performance assessment that out of 31 laboratories who participated, 28 laboratories resulted magnitude of En number less than 1 at every calibration points they submitted results in the range from 50 to $500^{\circ}C$. The results of about 75% of the laboratories showed the difference from the assigned values less than 1/10 of the tolerance level of the class B IPRT. This indicates that the participating calibration laboratories performed with satisfactory level that was enough to calibrate IPRTs to significant precision. The sensors used in this work were manufactured and chosen by the criteria of long-term instability less than 4 mK and hysteresis less than 8 mK in the temperature range used in this work. Furthermore, the change in the resistance of the sensors in the calibration temperature range were less than the uncertainty of the calibration, 25 mK (k=2).

• Transactions of the Korean Society of Mechanical Engineers B
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• v.28 no.12
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• pp.1475-1483
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• 2004

Loop thermosyphon(LTS) has many good characteristics such as low thermal resistance, no power consumption, noiseless operation and small size. To investigate the overall performance of LTS, we have performed various experiments varying three parameters: input power of the heater, working fluid(water, ethanol, FC3283) and filling ratio of the working fluid. At a combination of these parameters, temperature measurements are made at many locations of the LTS. The temperature difference between the evaporator and the condenser is used to obtain the thermal resistance. In addition, flow visualization using a high speed camera is carried out. The thermal resistance is not constant. It is lower at higher input power, which is one of the distinct merits of LTS. Flow instabilities are frequently observed when changing the working fluid, the input power and the filling ratio. The results show that the LTS can be readily put into practical use. Future practical application in electronic cooling is recommended.

• Proceedings of the KIPE Conference
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• 2013.07a
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• pp.354-355
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• 2013

Fundamental features of the arc stability in DC arc furnace of 720V/100kA/72MW have been investigated. Cassie-Mayr arc model has been employed and applied for the target dc arc furnace. In order to characterize the parameters of Cassie-Mayr arc model and the behavior of unstable arc dynamics, the advanced arc simulations of magneto-hydrodynamics (MHD) has been performed. The MHD based arc simulation has been validated in the subcomponent level, for the free burning arc set up in the laboratory. From the results of MHD simulation, dc arc dynamic resistance is proposed to be an effective arc stability function reflecting the instability of dynamic arc behavior. The experimental result confirms the usefulness of proposed dynamic arc resistance as arc stability function. The proposed arc stability function can be regarded as an effective criterion for the overall power conversion system to maintain highly stable arcing operation leading to better productivity and reliability.

• Proceedings of the KIPE Conference
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• 2012.07a
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• pp.371-372
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• 2012

In this paper fundamental features of the arc stability in DC arc furnace of 720V/100kA/72MW have been investigated. Cassie-Mayr arc model has been employed for the target dc arc furnace. In order to characterize the parameters of Cassie-Mayr arc model and the behavior of unstable arc dynamics, the advanced arc simulations of magneto-hydrodynamics (MHD) has been performed. Based on the results of MHD simulation, dc arc dynamic resistance is proposed to be an effective arc stability function reflecting the instability of dynamic arc behavior. The experimental result confirms the usefulness of proposed dynamic arc resistance as arc stability function. The proposed arc stability function can be regarded as an effective criterion for the overall power conversion system to maintain highly stable arcing operation leading to better productivity and reliability.

• Korean Journal Plant Pathology
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• v.12 no.4
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• pp.415-421
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• 1996

대전, 공주, 논산, 부여와 김해 등에서 병든 딸기, 토마토, 오이에서 총 992균주의 잿빛곰팡이병균을 분리하여 이들 균주로부터 dichlofluanid 저항성 5균주, 감수성 5균주를 임의로 선발하였다. 분리된 균의 dichlofluanid 저항성을 조사한 결과 105균주(10.6%)가 저항성이었다. 저항성균 균사의 최소 억제 농도(minimum inhibitory concentration)는 100~500$\mu\textrm{g}$/ml 이상이었으나 감수성균은 10 $\mu\textrm{g}$/ml 미만이었다. Dichlofluanid 저항성의 안정성 조사를 위하여 35$^{\circ}C$고온 처리 및 계대 배양할 때 조사된 저항성 5균주 중 3균주는 저항성이 감소하거나 상실되었다. 저온 저장 및 온실에 장기 보관할 때는 조사된 저항성 균주 모두가 저항성이 감소하거나 완전히 상실되는 것으로 나타났다. 이러한 결과는 이 약제에 대한 저항성이 불안정하다는 것을 나타낸다. 오이에 감수성균 및 저항성균을 혼합 접종한 후 재분리할 때 시간이 지날수록 감수성균이 더 많이 분리되어 저항성균의 경합 능력이 감수성 균주에 비하여 열등하였다.

• Journal of Chest Surgery
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• v.38 no.4 s.249
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• pp.277-283
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• 2005

Arterial oxygen saturation $(SaO_2)$ instability frequently takes place after systemic-pulmonary shunt without shunt occlusion. We analyzed actual incidence and risk factors for $SaO_2$ instability after shunt operations, and possible mechanisms were speculated on. Material and Method: Ninety three patients, who underwent modified Blalock-Taussig shunt from January 1996 to December 2000, were enrolled in this study. Adequacy of shunt was verified in all patients, either by ensuing one ventricle or biventricular repair later on or by appropriate pulmonary artery growth on postoperative angiogram. Age, body weight, hemoglobin level at operation were 3 day to 36 years (median: 1.8 months), 2.5kg to 51kg (median: 4.1kg) and $10.7\~24.3$ gm/dL (median: 15.2 gm/dL) respectively. Preoperative diagnoses were functional single ventricle with pulmonary stenosis or atresia in 39, tetralogy of Fallot in 38 and pulmonary atresia with intact ventricular septum in 16. Pulmonary blood flow (PBF) was maintained pre-operatively by patent ductus or previous shunt in 64 and by forward flow through stenotic right ventricular outflow tract (RVOT) in 29. $SaO_2$ instability was defined as $SaO_2$ less than $50\%$ for more than 1 hour with neither anatomic obstruction of shunt nor respiratory problem. Result: 10 patients $(10.7\%)$ showed $SaO_2$ instability after shunt operation. After shunt occlusion was ruled out by echocardiogram, they received measures to lower pulmonary vascular resistance (PVR), which worked within a few hours in all patients. Risk factors for $SaO_2$ instability included older age at operation (p=0.039), lower preoperative $SaO_2$ (p=0.0001) and emergency operation (p=0.001). PBF through stenotic RVOT showed marginal statistical significance (p=0.065). Conclusion: $SaO_2$ instability occurs frequently after shunt operation, especially in patients with severe hypoxia pre-operatively or unstable clinical condition necessitating emergency operation. Temporary elevation of pulmonary vascular resistance is a possible mechanism in this specific clinical setting.

• Korean Journal of Materials Research
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• v.16 no.9
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• pp.564-570
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• 2006

Silicides have been required to be below 40 nm-thick and to have low contact resistance without agglomeration at high silicidation temperature. We fabricated composite silicide layers on the wafers from Ni(20 nm)/Co(20 nm)/poly-Si(70 nm) structure by rapid thermal annealing of $700{\sim}1100^{\circ}C$ for 40 seconds. The sheet resistance, surface composition, cross-sectional microstructure, and surface roughness were investigated by a four point probe, a X-ray diffractometer, an Auger electron spectroscopy, a field emission scanning electron microscope, and a scanning probe microscope, respectively. The sheet resistance increased abruptly while thickness decreased as silicidation temperature increased. We propose that the fast metal diffusion along the silicon grain boundary lead to the poly silicon mixing and inversion. Our results imply that we may consider the serious thermal instability in designing and process for the sub-0.1 um CMOS devices.