• 한국화재소방학회논문지
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• 제33권6호
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• pp.114-119
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• 2019

우리는 LED등기구의 Printed circuit board (PCB)에서 화재의 원인으로 특정할 수 있는 금속 마이그레이션(Metallic migration) 현상을 발견하고, 본 연구를 진행하였다. 금속 마이그레이션 현상 가속화 실험인 물방울 시험을 소량의 물과 저전압(3 V)로 진행하고 절연되어있는 양극에서 직접적으로 금속 마이그레이션의 성장과 회로의 단락을 확인하였다. 그리고 전자주사현미경(SEM)을 통해 형태를 관찰하고 에너지 분산형 분광기(EDS)를 이용하여 성분을 분석한 결과, 절연된 부분에서 전극을 이루고 있는 구리의 성분을 검출하였다.

• 자동차안전학회지
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• 제13권2호
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• pp.30-34
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• 2021

Electrical failures and reliability problems of electronic components by ionic migration between adjacent device terminals have become an issue in automotive electronics. Especially unlike galvanic corrosion, ionic migration is occurred at high temperature and high humidity under applied electric field condition. Until now, although extensive studies of the ionic migrations dealing with PCBs, electrodes, and solders were reported, there is no study on the effect of insulation polymers and metallic fillers for ionic migration. In this research, therefore, ionic migration induced by the types and contents of polymers and metallic fillers, and variety conditions of temperature, humidity, and applied voltage was studied in detail. Ester and amide types of liquid crystal polymer (LCP) and poly (phthalamide) (PPA) were used as base polymers, respectively and compounded with the metallic fillers of Copper iodide (CuI), Zinc stearate (Zn-st), or Calcium stearate (Ca-st) in various compositions. The compounding polymers were fabricated in IPC-B-24 of SIR test coupon according to ISO 9455-17 with Cu electrodes for ionic migration test. While there is no change in LCP-based samples, ionic migration in PPA compounding sample with a high water absorption property was accelerated in the presence of 0.25 wt% or above of CuI at the environmental conditions of 85℃, 85% RH and 48V. The dendritic short-circuit growth of Cu caused by ionic migration between the electrodes on the surface of compounded polymers was systematically observed and analyzed by using optical microscopy and SEM (EDX).

• Clinics in Shoulder and Elbow
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• 제17권2호
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• pp.77-79
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• 2014

The migration of metallic devices such as Kirschner's wire (K-wire) from the shoulder is a well-recognized and significant complication of operation, the wire ending up in the lungs, the heart, the esophagus, the aorta or the subclavian artery. However, spinal migration is very rare. We report the case of a 72-year-old female patient with K-wire migration into the C7-T1 intervertebral foramen, 2 months after surgery for a lateral end fracture of left clavicle.

• Journal of Welding and Joining
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• 제23권2호
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• pp.32-40
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• 2005

• 한국재료학회지
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• 제15권1호
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• pp.54-60
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• 2005

Recently a lots of problems have observed in high densified and high integrated electronic components. One of them is ion migration phenomena, which induce the electrical short of electrical circuit. ion migration phenomena has been observed in the field of exposing the specific environment and using for a long tin e. This study was evaluated the generation time of ion migration and was investigated properly test method through water drop test and high temperature high humidity test. Also we observed direct causes and confirmed generation mechanism of dendritic growth as we reproduced the ion migration phenomena. We utilized PCB(printed circuit board) having a comb pattern as follows 0.5, 1.0, 2.0 mm pattern distance. Cu, SnPb and Au were electroplated on the comb pattern. 6.5 V and 15 V were applied in the comb pattern and then we measured the electrical short time causing by ion migration. In these results, we examined a difference of ion migration time depending on pattern materials, applied voltage and pattern spacing of PCB conductor.

• 한국진공학회지
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• 제5권3호
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• pp.194-198
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• 1996

Detailed expermental studies of theelectronic structure of the valence and conduction bands of the mixed conductor $\beta$-LiAlindicate that a quasi-gap opens at the Fermi level, and the conduction states are highlylocalized, as opposed to the theoretical band structure calculations that predict predominant metallic behavior. Evidence for complex lithium migration effects involving the surface of Lial , induced by particle (electron or ion) bombardment and mechanical treatment , has been obtained as a byproduct of these experiments.

• 대한소화기학회지
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• 제72권6호
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• pp.313-317
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• 2018

During laparoscopic cholecystectomy, a surgical clip is used to control the cystic duct and cystic artery. In the past, metallic clips were usually used, but over recent years, interest in the use of Hem-o-lok clips has increased. Surgical clip migration into the common bile duct (CBD) after laparoscopic cholecystectomy has rarely been reported and the majority of reported cases involved metallic clips. In this report, we describe the case of a 53-year-old woman who presented with abdominal pain caused by migration of a Hem-o-lok clip into the CBD. The patient had undergone laparoscopic cholecystectomy 10 months previously. Abdominal CT revealed an indistinct, minute, radiation-impermeable object in the distal CBD. The object was successfully removed by sphincterotomy via ERCP using a stone basket and was identified as a Hem-o-lok clip.

• 한국식품위생안전성학회지
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• 제22권1호
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• pp.52-56
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• 2007

본 연구는 국내 유통 중인 프라이팬, 냄비, 주전자, 불판 등 금속제 주방기구 총 71품목을 대상으로 안전성 및 오염 정도에 대한 기초 자료를 제공하고자 실시되었다. 현행 식품공전 금속제의 재질 규격은 Pb 10%, Sb 5%이하이며 용출 규격은 Pb 1.0 mg/L이하이다. 알루미늄, 스테인리스 및 주철 총 71품목의 금속제 주방기구에 대한 재질시험 결과 Pb은 0.06% 이하로 검출되었으나 기준이하였으며 Sb은 모든 제품에서 검출되지 않았다. 또한 이들 주방기구의 용출시험 결과에서도 기준치이하인 0.41mg/L의 Pb이 검출되어 국내 유통 중인 금속제 주방기구는 기준규격에 적합한 것으로 나타났다.

• 대한기관식도과학회지
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• 제10권2호
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• pp.17-21
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• 2004

Background Insertion of tracheal stent in the treatment of benign tracheal & bronchial disease has increased since the introduction of expandable metallic stent. Material & Methods : Between Jan, 1995 and Feb. 2004, eight patients who had benign tracheo-bronchial disease underwent insertion of expandable metallic tracheal stent. We retrospectively analyzed stent insertion indications, complications, and following the result. Results : Surgical indications were post-intubation tracheal stenosis (1 case), tracheal stenosis following tracheal surgery (2 cases), tracheo-esophageal fistula (2 cases), broncho-pleural fistula(1 case), left main bronchus stenosis following bronchoplasty (1 case), and left main bronchus stenosis due to mediastinal repositioning (1 case). Expandable metallic tracheal stent was inserted in five patients to resolve dyspnea caused by airway obstruction, and to prevent recurrent pneumonia in three patients. The complication developed in 6 patients $75\%$; 3 cases of distal stenosis due to growth of granulation tissue, and one case each of tearing of posterior membrane, aggravation of tracheo-esophageal fistula, and airway partial obstruction due to stent migration. The stent was removed in 5 patients and tracheal surgery (tracheal resection and end to end anastomosis with primary repair of esophagus, pericardial patch tracheo-bronchoplasty, tracheal repair and omental wrapping) was performed in 3 patients. Conclusion Insertion of self expandable metallic stent in benign tracheo-bronchial disease is an effective means of relieving dyspnea for only a short period, and it did not increase the long term survival. Better means of treatment of benign tracheo-bronchial stenosis in necessary.

• Nuclear Engineering and Technology
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• 제41권1호
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• pp.21-38
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• 2009

The use of multi scale modeling concepts and simulation techniques to study the destabilization of an ultrathin layer of oxide interface between a metal substrate and the surrounding environment is considered. Of particular interest are chemo-mechanical behavior of this interface in the context of a molecular-level description of stress corrosion cracking. Motivated by our previous molecular dynamics simulations of unit processes in materials strength and toughness, we examine the challenges of dealing with chemical reactivity on an equal footing with mechanical deformation, (a) understanding electron transfer processes using first-principles methods, (b) modeling cation transport and associated charged defect migration kinetics, and (c) simulation of pit nucleation and intergranular deformation to initiate the breakdown of the oxide interlayer. These problems illustrate a level of multi-scale complexity that would be practically impossible to attack by other means; they also point to a perspective framework that could guide future research in the broad computational science community.