전자 빔 조사 민감 물질의 전자회절분석을 위한 Imaging Plate 기술

김영민,김양수,김진규,이정용,김윤중 韓國電子顯微鏡學會 2008 Applied microscopy Vol.38 No.3

전자 빔 조사 민감 물질인 gibbsite (γ-Al(OH)₃)의 전자 빔 조사 상전이 연구에서 전자회절 자료의 기록에 대한 imaging plate 와 필름의 기록 특성을 실험적으로 비교하였다. Imaging plate는 극단적으로 낮은 전자 강도와 높은 전자 강도를 동시 기록하기에 충분한 선형 dynamic range를 갖기 때문에, 매우 낮은 전자조사 조건 (≤0.1 e-/μm²)에서 전자 회절 자료를 기록할 때 필름에 비해 회절 자료의 spatial frequency 범위가 두 배 이상 확장되었다. 심지어 이미 기록 포화된 투과 빔 주위의 신호 정보 레벨을 세분화하는 데에도 훨씬 우수한 분해 성능을 나타내었다. 따라서 본 연구 결과는 imaging plate가 극단적으로 낮은 전자강도 기록이 필요한 전자 빔 조사 민감 물질이나 cryo-biological 시편들의 구조 연구 관점에서 가장 적절한 기록 매체임을 나타낸다. An experimental comparison of the detection properties between imaging plate and film for recording the electron diffraction pattern was carried out on a radiation-sensitive material, an aluminum trihydroxide (gibbsite, γ-Al(OH)₃), through the electron beam irradiation. Because the imaging plate has a wide dynamic range sufficient for recording extremely low- and high-electron intensities, the range of spatial frequency for the diffraction pattern acquired by the imaging plate was extended to two times larger than the range by the film, especially at a low electron dose condition (≤0.1 e-/μm²). It is also demonstrated that the imaging plate showed better resolving power for discriminating fine intensity levels even in saturated transmitted beam. Hence, in the respect of investigating the structures of radiation-sensitive materials and cryobiological specimens, our experimental demonstrations suggest that the imaging plate technique may be a good choice for those studies, which have to use an extremely low electron intensity for recording.

투과전자현미경 내 직접 가열 실험에서의 실험적 문제들

김영민,김진규,김양수,오상호,김윤중 韓國電子顯微鏡學會 2008 Applied microscopy Vol.38 No.4

In performing in situ heating transmission electron microscopy (TEM) for materials characterizations, arising concerns such as specimen drifts and unintentional Cu contamination are discussed. In particular, we analysed the thermal and mechanical characteristics of in situ heating holders to estimate thermal drift phenomena. From the experimental results, we suggest an empirical model to describe the thermal drift behavior so that we can design an effective plan for in situ heating experiment. Practical approaches to minimize several hindrances arisen from the experiment are proposed. We believe that our experimental recommendations will be useful for a microscopist fascinated with the powerful potential of in situ heating TEM.

사망 진단서(시체 검안서) 작성의 문제점

김규석,임용수,이중의,서길준,윤여규,어은경,염석란,정연권,이윤성 대한응급의학회 2000 대한응급의학회지 Vol.11 No.4

Background: This study was conducted to analyze the current problems in completing death certificates and to identify the correct method for completing death certificates Methods: We reviewed 262 death certificates in three hospitals from March 1 to April 30, 2000, and 119 death certificates in one hospital from March 1 to 31, 2000. We identified major and minor errors and analyzed and compared them retrospectively. Results: A total of 381 death certificates were reviewed: 59 in Seoul National University Hospital,101 in Ewha Woman's University Hospital, and 102 in Gachon Medical College Hospital, which has no education program for completing death certificates in postgraduate training, and 119 in Samsung Medical Center which has an education program for completing death certificates. 358 certificates(94.0%) had at least one error. There were only 23 death certificates(6.0%) without an error. In 182 cases(47.8%), there was one major error. In 321 death certificates(84.3%), there were more than two errors. A comparison of Samsung Medical Center with the other hospitals showed that the number of total errors was statistically different(p=0.001). Conclusion: There were few death certificates without an error in this study. In a hospital which has postgraduate training in completing death certificates, there are fewer errors than in other hospitals which have no training course. Emergency physicians actually certify many deaths, so they must know the correct method of completing death certificates for statistics on morbidity and mortality.

빌트인 모터를 이용한 2축 제어 미세 가공기 개발

김건희,김효식,양순철,이상용,국명호,이선규,김윤중,홍권희 한국공작기계학회 2007 한국공작기계학회 추계학술대회논문집 Vol.2007 No.-

This paper describes development of low cost precision machine that has combined the Build-in Motor with a vacuum chuck. This study mainly aims to find out a cutting condition for maintaining optimum surface condition and to examine cutting characteristics of the precision machine that is equipped by diamond bites. The cutting materials is Al alloy. Several experiments were carried out to find out the main factors that affect the surface roughness such as principal axis RPM(rotation per minute), feeding speed, and cutting depth. As a result, we obtain The optimum cutting condition of the developed precision machine.

전자토모그래피의 정량적 분석에서 대물렌즈 조리개의 영향

김진규,이상희,권희석,정종만,정원구,이수정,주형태,김윤중 韓國電子顯微鏡學會 2008 Applied microscopy Vol.38 No.4

Electron tomography의 정량적 분석을 위해서 대물렌즈 조리개가 투과빔의 강도에 미치는 영향을 평가하였다. Electron tomography에 도입되는 Beer’s law의 올바른 적용을 위해서는 투과빔은 시료의 기울기에 따른 mass thickness의 변화에 의한 효과만을 반영해야 한다. 그러므로 빔 경로상의 대물렌즈 조리개, 홀더 등에 의한 다른 효과는 제거되어야 한다. 본 연구에서는 대물렌즈 조리개의 cut-off 효과를 120 kV TEM과 Quantifoil holey 카본 시료를 이용하여 상세히 평가하였다. 대물렌즈 조리개를 사용하지 않은 경우와 비교할 때, 30 μm 크기의 대물렌즈 조리개를 통과한 투과전자빔의 강도는 약 16.7%의 감소가 일어난다. 또한 55˚이상의 고경사각 기울기에서는 대물렌즈 조리개의 cut-off 효과에 의해 14.2%의 강도 감소가 추가적으로 발생함을 알 수 있었다. Electron tomography에서 정량적 분석을 위해서는 이러한 대물렌즈 조리개의 영향을 고려해야만 한다. 또한 Beer’s law의 올바른 적용을 위해서는 일련의 기울기에 따른 2차원적 영상은 가능하면 대물렌즈 조리개를 사용하지 않은 상태에서 획득하는 것이 바람직하다. We have evaluated the effects of experimental factors on transmitted electron beam intensities for quantitative analysis in electron tomography. For the correct application of Beer’s law in electron tomography, the transmitted beam intensity should reflect the net effect of mass properties on beam path. So, the any other effects of the objective aperture and the specimen holder on beam path should be removed. The cut-off effects of objective aperture were examined using Quantifoil holey carbon film and a transmission electron microscope operated at 120 kV. The transmitted beam intensities with 30 μm objective aperture dropped about 16.7% compared to electron beam intensities without the objective aperture. Also, the additional losses of about 14.2% at high tilt angles were occurred by cut-off effects of the objective apertures. For the precise quantitative analysis in electron tomography, the effect of the objective aperture on transmitted electron beam intensities should be considered. It is desirable that 2-D tilt series images are obtained without the objective aperture for correct application of Bee’s law.

만성 요통 환자의 심리사회적 특성

김용민,원중희,최의성,서중배,이호승,허윤무 충북대학교 의학연구소 2001 忠北醫大學術誌 Vol.11 No.2

연구목적: 만성 요통 환자의 많은 수가 직업 등 주변 환경과 심리 상태의 영향을 받는 것으로 추정되나 그 연관성은 아직 논란이 많다. 본 연구에서는 설문 조사를 통하여 만성 요통 환자의 심리사회적 특성을 알아보고자 하였다. 대상 및 방법. 1997년 7월부터 1998년 12월까지 6주 이상 지속된 만성 요통으로 본원 정형외과 외래를 내원한 환자들 중 기질적 원인이 불명확한 62명의 환자들에서 직업, 유발요인, 치료 등 요통 관련 요소 설문과 Minnesota Multiphasic Personal Inventory (MMPI)를 실시하였다. 요통 관련 사항에는 통증의 기간, 정도, 통증이 유발 또는 심해지는 자세, 그리고 본인이 생각하는 요통의 원인 등을 포함하였다. MMPI는 전체 평균을 이용한 방법과 two-code 방법을 이용하여 평가하였다. 결과: 만성 요통환자의 직업 상 실내에서 앉아 일하는 직업이 가장 맡았으며 일정한 자세를 오래 유지하며 앉거나 서 있는 경우 증상이 악화되는 것으로 기술되었다. MMPI에서는 건강 염려증, 우울증, 히스테리의 세 척도의 평균이 55이상으로 상승되어 있었다. Two-code 방법에서는 92% (46/50)의 환자에서 위 세 척도 중 적어도 하나 이상 상승되어 있었다. 결론: 만성 요통 환자들에서 일상 생활의 자세와 직업이 요통의 발생 및 악화에 영향이 있을 것으로 보여졌다. MMPI를 통한 심리 인성 검사 상 건강 염려증, 우울증, 히스테리의 성향이 증가되어 있어 요통의 발생과 만성화에 심리적 요소가 영향을 미치는 것으로 보여졌다. 사회경제학적, 정신심리학적 요인이 만성 요통에 미치는 영향의 규명을 위한 다양하고 심도 있는 연구가 필요하다고 생각된다. Purpose : Socioeconomic and psychologic factors seem to affect incidence, severity, and chronicity of low back pain. Purpose of this study is to survey socioeconomic factors and document psychoneurotic traits via MMPI in chronic low back pain patients. Materials and Methods : From July 1997 to December 1998, questionnaire about low back pain-related factors such as duration, severity, posture, occupation etc. and MMPI were given to patients who visited our department for chronic low back pain()6weeks). 62 patients completed, and 50 of them completed MMPI. The answers were analyzed. MMPI scores were evaluated in mean±SD method and two-code method. Results : Sedentary workers were the most common. And symptoms were told to be elicited by long sitting or standing posture(job) . Hs, D, Hy scales of MMPI, which are know as "neurotic triad by two-code method was observed in 92% (46/50) . Conclusion : It seemed that job and posture had Important role in chronic low back pain. And, it seemed that chronic low back pain patients had some psychoneurotic traits especially in hypochondriasis, depression, and hysteria. More investigations to document the influences of socioeconomic and psychoneurotic factors in chronic low back pain seems to be necessary.

강산 및 강알칼리 음독에서 냉각 용액을 사용한 희석 요법과 중화 요법의 가능성

이중의,송형곤,김동훈,권운용,곽영호,서길준,윤여규 대한응급의학회 2001 대한응급의학회지 Vol.12 No.3

Background: There is no effective treatment modality for caustic agent ingestion. Dilution and neutralization are prohibited because of the risk of secondary thermal injury. This experiment is designed to evaluate the amount of dilution and neutralization heat and to gauge the applicability of dilution and neutralization therapy using cold solutions to suppress the peak temperature. Methods: This is an in-vitro chemical experiment. HCl, CH3COOH, NaOH, and NH4OH are selected as representatives of strong and weak acids and strong and weak alkali, respectively. 20℃, 11.6M, 5.8M, and 2.9M solutions of each acid and alkali are made and mixed using a magnetic stirrer at a room air temperature of 28℃. The peak temperature, the duration above 40℃, and the heat amount are measured or calculated. Results: When a 11.6M HCl or NaOH solution is diluted with same amount of water, 32 or 18cal. per mL of HCl or NaOH is produced, respectively. HCl produces a significant peak temperature, but NaOH does not. The lower the concentration, the lower the amount of heat production. 11.6M CH3COOH and NH4OH solutions don't produce dilution heat.11.6M and 5.8M solutions of all acids and alkali produce destructive neutralization heat. However, 2.9M solutions produce neutralization heat which might be controllable. When a 11.6M HCl or NaOH solution is neutralized with a -10℃ 2.9 M NaOH or HCl solution, respectively, the peak temperature produced is below 40℃ and seems to add little thermal damage to viable tissue. Conclusion: Dilution and neutralization with a cold solution in cases of strong acid or alkali ingestion is a promising method to avoid thermal injury.

발열이 있는 호중구 감소증 환자에서의 위험도 예측인자

정중식,권운용,김규석,임용수,이중의,서길준,윤여규 대한응급의학회 2000 대한응급의학회지 Vol.11 No.3

Background: Most febrile neutropenic patients are treated in an aggressive manner. However, identification of low-risk patients may enable clinicians to administer risk-based treatment. The object of this study is to certify the factors associated with increased risk at the time of visiting the emergency department. Methods: This is a retrospective study. We reviewed the medical records of 101 febrile neutropenic patients who had visited the emergency department of Seoul National University Hospital from January 1998 to August 1999. We assumed 22 risk prediction factors that could be assessed at admission to the emergency department and 5 factors that could be assessed during treatment course. To find independent risk-prediction factors, we analyzed these factors respectively by using multiple regression analysis. Results: Tachycardia(aOR=136.5), altered mentality(aOR=28.8), decreased renal function(aOR=20.1), and significant comorbidity(aOR=17,2) are the independent factors associated with higher mortality. Altered mentality(aOR=31.6) and decreased renal function(CCr < 75㎖/min, aOR=5.4) are those associated with a higher incidence of septic shock. Independent factors associated with persistent(more than 3 days) fever are the early(within 10 days) onset of fever after last chemotherapy(aOR=8.8) and the existence of new pulmonary infiltrates on a simple chest X-ray(aOR=4.3). Conclusion: The stability of vital signs, the change of mentality, the renal function, the existence of significant comorbidity, the existence of new pulmonary infiltrates, and the rate of neutropenia are clinically useful risk-prediction factors in febrile neutropenia at the time of visiting the emergency department.

압력용기 구조물 용접부에서 잔류응력이 피로균열진전거동에 미치는 영향

이연신,차용훈,김덕중,성백섭 朝鮮大學校 機械技術硏究所 1999 機械技術硏究 Vol.2 No.2

This paper is to investigated the influence of welding residual stresses on the fatigue crack growth behaviors in the vertical direction to the weld bead. So, Co₂Automatic welding was performed on the ASTM A5l6 grade 60 Steel. For skip and continuous fillet welding, the specimens of fatigue cracks are initiated at toe end and beginning of welded specimen. The fatigue life of continue fillet welding is greater then that of skip fillet welding. The fatigue lief of as welded specimen is longer than that of PWHT specimen because the compression residual stress are greater than the other zone, which are near the welding toe notch of welded specimen. For skip and continuous fillet welding, da/dN-ΔK relations show retardation at HAZ and increase linearly at the stable growth region.

부하 감지 유압 서어보 시스템의 신경회로망 제어

박중윤,김영태,김성동,김종선 金烏工科大學校 1991 論文集 Vol.12 No.-

The positive feedback property of the load-sensing mechanism deteriorates the control performance of the hydraulic system while this mechanism improves the energy efficiency of the system. This paper considers a neutral net control in order to achieve good control performance of the load-sensing hydraulic system. The proposed controller has a structure of multilayer perceptron and it is learned by a feedback error signal and the back propagation algorithm. The results of the simulation studies show that the neural net controller can produce better control performance than conventional PID controller in nonlinear systems such as hydraulic systems. The neural net control system also shows excellent trajectory tracking performance and robustness against external disturbances.