시작 노트_이서원

이서원 고요아침 2013 시조시학 Vol.49 No.-

2008년 부산일보 신춘문예 - 이서원

이서원 고요아침 2008 시조시학 Vol.- No.-

Effect of Spin Memory Loss on Spin Transfer Torque

이서원,이경진 한국물리학회 2009 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.55 No.4

We investigate how the spin memory loss at interfaces affects the spin transfer torque in the framework of the drift-diffusion model. The spin memory loss changes the spin accumulation in the non-magnetic spacer separating the two ferromagnets in a spin valve structure and, thus, the spin transfer torque. By comparing theoretical values of the spin transfer torque with experimental results, we found that non-zero spin memory loss is essential to explain the experimental switching current densities in the current-induced magnetization switching. The spin memory loss determined by the comparison is in good agreement with the value determined by experimental measurement of giant magnetoresistance.

플립칩 패키지내 Sn-3.5Ag 솔더범프의 electromigration

이서원,오태성 한국마이크로전자및패키징학회 2003 마이크로전자 및 패키징학회지 Vol.10 No.4

상부 칩과 하부 기판이 모두 Si으로 구성되어 있는 플립칩 패키지 시편을 제조하여 Sn-3.5Ag 솔더범프의 electromigration 거동을 분석하였다. Sn-3.5Ag 솔더범프의 electromigration 테스트 초기부터 파단이 일어나기 직전까지는 플립칩 시편의 저항이 거의 변하지 않았으나, 파단이 발생하는 순간 저항값이 크게 증가하였다. 전류밀도 $3\times 10^4$∼$4\times 10^4$A/$\textrm{cm}^2$에서 Sn-3.5Ag 솔더범프의 electromigration에 대한 활성화 에너지는 ∼0.7 eV로 분석되었다. Sn-3.5Ag 솔더범프의 cathode 부위의 솔더/UBM 계면에서 void의 형성 및 전파에 의해 솔더범프의 파단이 발생하였다. Electromigration of Sn-3.5Ag solder bump was investigated using flip chip specimens which consisted of upper Si chip and lower Si substrate. While the resistance of the flip chip sample did not almost change until the time right before the failure, the resistivity increased abruptly at the moment when complete failure of the solder joint occurred in the flip chip sample. At current densities of $3\times 10^4$∼$4\times 10^4$A/$\textrm{cm}^2$, the activation energy for electromigration of the Sn-3.5Ag solder bump was characterized as ∼0.7 eV. Failure of the Sn-3.5Ag solder bump occurred at the solder/UBM interface due to the formation and propagation of voids at cathode side of the solder bump.

외상에 의해 동시에 발생한 가성 좌심실류와 하행 대동맥류의 치험1례

이서원,이계선 대한흉부심장혈관외과학회 1997 Journal of Chest Surgery (J Chest Surg) Vol.30 No.6

Traumatic aneurysm of both the thoracic aorta and the left ventricle are extremely rare in children because it is characterized by high mortality. We report a case which we experienced recently with sucessful outcome. A Five-year-old boy had a blunt trauma by bongo bus. He had pulmonary hemorrage and pericardial effusion complicated by multiorgan failure threatening his life. Aneurysm of LV and Descending aorta were showed by 2-D echocardiogram and MRI. The atient underwent successful corrective surgery 2 and half momths after trauma, the Postoperative status of this patient was uneventful, now he is being followed up the OPD. 외상에 의한 흉부손상중 좌심실류와 하행대동맥류는 매우 드문데 그 이유는 아마도 대부분의 환자가 사고 당시 즉시 사망하기 때문일 것이다. 본 예는 5세 남자 환아로 버스에 치어 급성호흡부전과 폐부종으로 인한 ARDS 로 다발성 장기부전이 발생하여 뇌경색과 신부전의 합병증이 동반되어 치료후 퇴원하여 외래 추적조사중 심초음파 검사상 좌심실류와 전자자기공명(hm))상 좌심실류 및 하행대동맥류 진단하에 외상후 74일만에 전순환 정지하에 좌심실류절제술과 하행대동맥류절제술 및 인조혈관대체술을 시행하였으며, 술후 환자는 특별한 문제없이 퇴원하였다.

개심술 450례의 임상적 고찰

이서원,이계선 대한흉부심장혈관외과학회 1997 Journal of Chest Surgery (J Chest Surg) Vol.30 No.8

From Feb. 1985 to Aug. 1996, 450 patients underwent open heart surgery with hypothermic cardiopulmonary bypass. In 450 cases of open heart surgery, 222 cases(49.3%) were congenital heart diseases and 228 cases(5 .7%) were acquired heart diseases. In 222 cases of congenital heart diseases, there were 201 cases of acyanotic heart disease and 21 cases of cyanotic heart diseases. Among the 228 cases of acquired heart diseases, most cases were valvular heart diseases in which 206 valves were implanted. There were 32 cases of ischemic heart disease and the average graft anastomoses were 2.37 sites per operation. The operative mortality of congenital and acquired disease was 9.0% and 10.l% respectively and then overall mortality rate was 9.6% . 본원에서는 1985년 2월 부터 1996년 8월까지 450례의 개심술을 시행하였다. 450례중 선천성 심질환은 222례(49.3%), 후천성 심질환은 228례(50.7%)로 거의 비슷한 비율이었으며, 후반 기 5년간은 후천성 심질환이 더 많았다. 선천성 심질환은 비청색증심질환이 201례, 청색증 심질환이 21례를 차지 하였으며, 수술 사망율은 각각 5.5%와 38.1%를 차지하였다. 청색증 심질환은 대부분 활롯 4징증 이었다. 후천성 심질환 228례중 판막질환은 17례, 허혈성 심질환은 32례, 대동맥 질환은 12례, 심장종양은 6례 있었다. 판막질환은 승모판치환술이 87fll, 대동맥판막 치환술이 45례, 이중판막 치환술이 35례를 차지하였다. 허혈성 심장병의 평균문합순는 2.37개소 였으며, 사망율은 6.3%였다. 판막질환의 사망율은 10.8%, 대동맥질 환의 사망율은 16.7%였다. 전체 사망율은 9.6%이며, 선천성 심질환은 9.0%, 후천성 심질환은 10.1%였다.

자연기흉에서 비디오흉강경과 개흉술에 의한 기포제거술의 비교 : Comparison of VATS Versus Limited Thoracotomy

이서원,이계선,정진악,금동윤,안정태,이재원 凡石學術奬學財團 1999 凡石學術論文集 Vol.3 No.-

관상동맥 우회로술시 심근보호법에 따른 수술결과의 임상분석

이서원,이계선 대한흉부심장혈관외과학회 1997 Journal of Chest Surgery (J Chest Surg) Vol.30 No.10

대전을지병원 흉부외과에서는 1991년 10월 부터 1996년 4월까지 27명의 관상동맥우회로술을 시행하였으며 심정지액을 사용한 A그룹과 사용하지않은 B그룹으로 구분하여 조사하였다. 남자는 17명, 여자는 10명 이었 으며 연령은 45세에서 76세까지 분포하였으며 평균연령은 65세였다. 술전 임상소견으로는 안전성 협심증 11 례,불안전성 협심증 13례, 심근경색후 협심증이 3례였다. 동반질환으로 고혈압 7례, 당뇨병 5례 및 기타질환 이 3례있었다. 환자당 평균 혈관문합수는 A군에서 2.0개소, B군에서는 2.83개소의 원위문합을 하였다. 대동 맥 차단시간은 A군에서 54.7분, B군에서는 18.5분이었다. 술중 혹은 술후 발생한 심근경색증은 A군에서 2례, B군에서 3례 였으며, 전체파망율은 4례론 14.8%이며 B군의 사망율은 8.3%였다. From October 1991 to April 1996, 27 patients underwent aortocoronary bypass graft. There were 17 men, 10 women. The mean age was 65 years(range 45 to 76). The preoperative clinical status were chronic stable angina in 11 cases, unstable angina in 13 cases and postinfarction angina in 3 cases. The involved ri k factors were as follows: Hypertension in 7 cases, Diabetes Mellitus in 5 cases and any other diseases in 3 cases We divided these patients into two groups in this survey: The A group was 15 patients who were managed with cardioplegia from 1991 to 1994. The B group of 12 patients was done with intermittent aortic clamping without cardioplegia from 1995 to 1996. The mean numbers of graft per patient was 2.0 in A group and 2.83 in B group. The ischemic time per graft was 27.3 minute in A group and 18.5 minute in B group respectively. The morbidity was occlusion of grafted vessel in one patient and one of postoperative angina in A group. The total mortality was 14.8%(4/27), but mortality of B group was 8.35 (1/12)

자연기흉에서 비디오흉강경과 개흉술에 의한 기포제거술의 비교

이서원,이계선,정진악,금동윤,안정태,이재원 대한흉부심장혈관외과학회 1998 Journal of Chest Surgery (J Chest Surg) Vol.31 No.4

The bullectomy through the limited transaxillary thoracotomy and video-assisted thoracic surgery(VATS) had been used in operative management of spontaneous pneumothorax from Jan. 1994 to July 1997. The study comprised a retrospective review of 42 cases which were treated by limited thoracotomy, and 61 cases treated by video-assisted thoracoscopic sugery. We retrospectively reviewed annual incidnce of bullectomy. Analysis of video-assised thoracoscopic surgery and open bullectomy including age, sex, operative sites, surgical indications, associated diseases, operative time, posoperatve complications and hospital courses. There was no significant difference for operation time in two groups, 98.3${\pm}$38.4 minutes in thoracotomy and 95.7${\pm}$31.5 minutes in VATS. Prolonged air leakage over 7 days was observed in 8 cases from thoracotomy group, 4 cases from VATS group. 3 cases of recurrent pneumothorax were found from VATS group, but no recurrence was occurred from open bullectomy group. There were significant differences in postoperative hospital stay (8.0${\pm}$3.9 day in thoracotomy vs 5.9${\pm}$2.4day in VATS(P=0.001)), and indwelling period of chest tube after operation( 5.8${\pm}$3.0day in thoracotomy vs 4.0${\pm}$2.0day in VATS(P=0.0006)). 대전을지병원 흉부외과에서는 1994년 1월부터 1997년 7월까지 자연성 기흉에서 비디오흉강경을 이용한 기포제거술 61례와 개흉술을 이용한 기포제거술 42례를 후향적으로 비교분석하여 두 집단사이에 수술시간은 개흉술이 98.3$\pm$38.4분, 비디오흉강경술이 95.7$\pm$31.5분으로 비슷하였으나 술후 재원기간은 개흉술에서 8.0$\pm$3.9일, 비디오흉강경에서 5.9$\pm$2.4일(P=0.001)이었으며, 술후 흉관삽관기간은 개흉술에서 5.8$\pm$3.0일, 비디오흉강경술에서 4.0$\pm$2.0일(P=0.0006)으로 의미가 있었으며, 합병증 발생에서는 비디오흉강경을 이용한 기포제거술에서 7일 이상 공기누출이 4례, 개흉술에서 8례로 만족할만한 결과를 얻었다.

자활사업 참여자의 자아존중감이 자활효과에 미치는 영향 : 음주의 매개효과

이서원,장용언,한지숙 알코올과 건강행동학회 2011 알코올과 건강행동연구 Vol.12 No.2

Objectives: This study examines the effect of self-esteem on the self-sufficiency effectiveness and defines moderating effect of drinking, and then it tries to propose intervention methods to enhance the self-sufficiency effectiveness. Methods: For this purpose, the data was collected from 467 participants who belong to 27 local self-sufficiency centers out of 31 centers in Seoul. Descriptive analysis and Multiple-regression analysis were applied to test research hypothesis. Results: First, 124 (26.8%) of 467 participants had drinking problem over 12 points in AUDIT-K. Specially, 99 participants (19.9%) who have alcoholic problems over 15 points in AUDIT-K were needed immediate intervention. Second, there was a positive relationship between self-esteem and self-sufficiency effectiveness. It means that an intervention is necessary to enhance self-esteem for higher self-sufficiency effectiveness. Third, drinking had moderating effect within the relationship of self-esteem and self-sufficiency effectiveness. Drinking was negatively effects on self-sufficiency effectiveness. It means that an intervention is necessary against drinking for higher self-sufficiency effectiveness. Conclusion: Based on these research results, this study suggests that there is a necessity for intervention for the purpose of enhancement of self-sufficiency effectiveness.