수치해석을 통한 오븐건조 작업에서의 칼라 강판 온도예측

이태우,이경우,최민석,이덕재 대한금속재료학회 2004 대한금속·재료학회지 Vol.42 No.4

Paint coating process on steel sheet has to be carried out for producing prepainted steel sheet by continuous process. After coating process, drying processes are needed. Temperature control of oven system directly affects on the product quality, such as, a coherence of coating and state of surface. In this study, heat transfer coefficients were calculated by 3-dimensional heat flow analysis from hot wind of nozzle to steel sheet and values of PMT(Peak Metal Temperature) of steel sheets were predicted by adapting that value to 2-dimensional analysis and using the coefficients. Conditions of numerical analysis were obtained from orthogonal arrary which is known as Taguchi method. Coefficients of heat transfer coefficient equation were derived from the second order regression model. By comparing numerical analysis with experimental results, the accuracy of numerical analysis was verified. Moreover we analyzed the effect of various conditon of factors, such as velocity and thickness of steel sheet, temperature of hot wind and the type of steel sheet. (Received December 17, 2003)

방사선사진에서의 골질과 임상적으로 평가한 골질 분류의 상관관계

김현우,허경회,박관수,김정화,이원진,허민석,이삼선,최순철 대한구강악안면방사선학회 2006 Imaging Science in Dentistry Vol.37 No.1

Purpose : To investigate the validity of digital image processing on panoramic radiographs in estimating bone quality before endosseous dental implant installation by correlating bone quality in radiographic images with clinical bone quality classification. Materials and Methods : An experienced surgeon assessed and classified bone quality for implant sites with tactile sensation at the time of implant placement. Including fractal dimension eighteen morphologic features of trabecular pattern were examined in each anatomical sites on panoramic radiographs. Finally bone quality of 67 implant sites were evaluated in 42 patients. Results : Pearson correlation analysis showed that three morphologic parameters had weak linear negative correlation with clinical bone quality classification showing correlation coefficients of -0.276, -0.280, and -0.289, respectively (p<0.05). And other three morphologic parameters had obvious linear negative correlation with clinical bone quality classification showing correlation coefficients of -0.346, -0.488, and -0.343 respectively (p<0.05). Fractal dimension also had a linear correlation with clinical bone quality classification with correlation coefficients -0.506 significantly (p<0.05). Conclusion : This study suggests that fractal and morphometric analysis using digital panoramic radiographs can be used to evaluate bone quality for implant recipient sites. (Korean J Oral Maxillofac Radiol 2006; 36 : 25-32)

구강외과 수술용 스텐트 기반 영상유도 수술 시스템의 개발

이우진,김대승,이원진,이삼선,최순철,허민석,허경회,김명진,이지호 대한구강악안면방사선학회 2009 Imaging Science in Dentistry Vol.39 No.3

Purpose : The purpose of this study was to develop a stent-based image guided surgery system and to apply it to oral and maxillofacial surgeries for anatomically complex sites. Materials and Methods : We devised a patient-specific stent for patient-to-image registration and navigation. Threedimensional positions of the reference probe and the tool probe were tracked by an optical camera system and the relative position of the handpiece drill tip to the reference probe was monitored continuously on the monitor of a PC. Using 8 landmarks for measuring accuracy, the spatial discrepancy between CT image coordinate and physical coordinate was calculated for testing the normality. Results : The accuracy over 8 anatomical landmarks showed an overall mean of 0.56±0.16 mm. The developed system was applied to a surgery for a vertical alveolar bone augmentation in right mandibular posterior area and possible interior alveolar nerve injury case of an impacted third molar. The developed system provided continuous monitoring of invisible anatomical structures during operation and 3D information for operation sites. The clinical challenge showed sufficient accuracy and availability of anatomically complex operation sites. Conclusion : The developed system showed sufficient accuracy and availability in oral and maxillofacial surgeries for anatomically complex sites. (Korean J Oral Maxillofac Radiol 2009; 39 : 149-56)

의원성 사고로 발생한 타액선염 : 증례보고

김현우,허경회,이원진,허민석,이삼선,최순철 대한구강악안면방사선학회 2004 Imaging Science in Dentistry Vol.34 No.2

A case of sialadenitis is presented in a patient with painful swelling of the right mouth floor. The condition was caused by trauma on the right mouth floor during dental treatment, which had happened 15 days before admission. On aspiration, mucous secretion was found and ultrasonography showed obstruction of duct. Histopathological studies and surgical investigation established a definite diagnosis of obstructive sialadenitis caused by ductal laceration. As surgical treatment sialodochoplasty was selected. The case and relevant considerations are discussed.

한국인 제2형 당뇨병 환자의 골격근에서 인슐린 신호전달체계의 결함

최준혁,이관우,김효정,이동훈,이종우,김정은,엄현채,김경미,최성이,정윤석,김현만 대한내분비학회 2002 Endocrinology and metabolism Vol.17 No.5

연구배경: 제2형 당뇨병에서 나타나는 인슐린 저항성은 간, 지방, 근육 같은 말초조직에서 인슐린의 작용이 떨어지는 것을 말한다. 제2형 당뇨병의 발생기전에 인슐린 저항성과 인슐린 분비능 저하가 같이 관여함은 잘 알려진 사실이다. 인슐린의 세포내에서의 저항성을 규명하기 위한 인슐린의 세포내 신호전달체계에 대한 연구가 활발히 진행되고 있으며 몇몇 연구에서 인슐린 저항성을 가진 골격근육에서 IRS와 관련된 PI3-kinase의 활성감소와 Akt kinase의 활성감소를 보고하고 있으나 아직까지 명확하게 그 기작이 설명되어지지 않고 있다. 본 연구에서는 정상성인, 제2형 당뇨병 환자를 대상으로 경구당부하검사 및 인슐린 클램프검사를 시행하고 인슐린 클램프 검사시 대상인의 근육을 채취하여 인슐린 신호전달 체계(IR-β, IRS, Akt(PKB, Rac) kinase, GSK-3)를 연구하였다. 방법: 연구대상자는 한국인으로서 경구당부하검사상 정상인 및 당뇨병 환자 각각 11명, 9명을 대상으로 하였으며, 정상인은 건강인으로 과거력상 당대사에 영향을 줄 질환이 없고, 현재 당대사에 영향을 줄 약물 복용 및 다른 소견이 없는 경구당부하검사상 정성 내당능을 보이는 대상자로 하였다. 당뇨병환자는 모두 제2형 당뇨병 환자로 이환기간이 만 5년 이내인 경우로 하고, 인슐린으로 치료하는 대상자는 제외하도록 하였다. 대상자의 연령, 체질량지수, 체지방량, 공복시 총콜레스테롤, 중성지방, 고밀도지단백 콜레스테롤 및 HbA1c, 인슐린, C-peptide를 측정하였고, "HOMA model"을 이용하여 베타세포의 기능와 인슐린저항성 정도를 평가하였다. 정상혈당클램프 검사(euhlycemic hyperinsulinemic clamp test)를 시행하고 인슐린 투입 전과 인슐린 투입 30분후, 두차례에 걸쳐 대퇴부 근육생검을 실시한후 western 법으로 IR-β, IRS, Akt kinase, GSK-3의 인산화량을 측정하였다. 결과: 정상인 11명과 당뇨병 환자 9명을 대상으로 하였으며 대상자의 평균 연령, 평균 체질량지수, 체지방량, 허리/엉덩이 둘레의 비(waist hip ratio; WHR)는 두 군간에 차이가 없었다. 평균 공복혈당은 정상군 98.0±0.3㎎/dL, 당뇨병군 208.1±16.5㎎/dL(p<0.05), HbA1c는 정상군 5.4±0.5%, 당뇨병군 9.2±0.6%(p<0.05)였다. "HOMA model"을 이용한 베타세포의 기능과 인슐린저항성은 정상군 56.4±8.5%, 1.4±0.2, 당뇨병군 72.2±52.3%(p<0.01), 10.2±6.3(p<0.01)였으며 정상혈당클램프 검사상 포도당 이용률은 정상군 8.2±0.6㎎/㎏/min, 당뇨병군 3.7±1.1㎎/㎏/min(p<0.01)로 정상군과 당뇨병군간에 유의한 차이를 나타내었다. Western blot법으로 IR-β, IRS, Akt kinase, GSK-3의 인산화량을 인슐린 투입전과 인슐린 투입 30분후 측정하였을 때 IR-β에서는 정상군이 103.9±2.3에서 241.3±18.6, 당뇨군이 108.9±2.2에서 198.7±6.3으로 증가하였다(p=NS). 이는 인슐린 투입후 당뇨병군이 정상군과 비교하여 인산화량의 증가정도가 통계적인 차이가 없었다. IRS에서는 정상군이 111.6±7.3에서 295.6±17.2, 당뇨군이 114.5±6.1에서 222.0±23.2로 증가하였으며(p<0.05), 인슐린 투입후 당뇨병군이 정상군과 비교하여 인산화량의 증가정도가 약 24% 감소하였다. Akt kinase에서는 103.4±6.0에서 416.8±29.5로 증가하였으며(p<0.01), 인슐린 투입후 당뇨병군이 정상군과 비교하여 인산화량의 증가정도가 약 43% 감소하였다. GSK-3에서는 정상군이 107.7±6.7에서 595.7±28.1, 당뇨군이 104.3±4.8에서 443.3±12.9로 증가하였으며(p<0.01), 인슐린 투입후 당뇨병군이 정상군과 비교하여 인산화량의 증가정도가 약 25% 감소하였다. 결론: 제2형 당뇨병 환자에서 정상인과 비교하여 인슐린 자극후 IR-β는 인산화량의 증가정도가 큰 차이가 없었으나, IRS, Akt kinase, GSK-3에서는 인산화량의 증가 정도가 감소되는 것으로 보아 상위 인슐린 신호전단체계부터 결함이 있는 것으로 생각된다. Background: The glucose uptake rate is the limiting step in glucose utilization and storage. The failure of insulin to stimulate glucose uptake in muscle appears to be a primary defect of insulin resistance. This study was undertaken to examine the effect of physiological hyperinsulinemia on the phosphorylation of the insulin receptor (IR-β), insulin receptor substrate (IRS), Akt kinase and GSK-3 in isolated skeletal muscle, in people with type 2 diabetes(n=9) and control subjects(n=11). Methods: 75g OGTT and euglycemic hyperinsulinemic clamp test were done. And vastus lateralis muscle was obtained before and 30 min into the euglycemic clamp. Western blots were performed for tyrosine phosphroylation of insulin receptor substrate (IRS) and phosphorylation of the insulin receptor(IR-β), Akt and GSK-3. Result: There were no statistical differences in the mean age, BMI and body fat between the control subjects and diabetic patients. The fasting blood sugar and HbA_1c in controls and diabetic patients were 98.0±0.3 and 208.1±16.5ng/dl, and 5.4±0.5 and 9.2±0.6%, and 1.4±0.2 in the control subjects, and 72.2±52.3%(p<0.01) and 10.2±6.3(p<0.01) in the diabetic patients, respectively. The insulin resistance from the euglycemic hyperinsulinemic clamp test were 8.2±0.6㎎/㎏/min and 3.7±1.1ng/㎏/min in the control subjects and in the diabetic patients, respectively(p<0.01). Compared with the normal controls, insulin-stimulated IR phosphorylation was no different to that in the diabetic patients. However, insulin-stimulated IRS phosphorylation, insulin-stimulated Akt phosphorylation and insulin-stimulated GSK-3 phosphorylation were reduced in the diabetic patients compared with the normal controls by 24, 43 and 25%, respectively(p<0.05). Conclusion: In Korean type 2 diabetic patients, the insulin resistance may be due to the impairment of the upstream insulin signal molecular network. Further studies will focus on determining whether these signaling defects are the cause of the development of insulin resistance, or secondary to the altered metabolic state, associated with type 2 diabetes mellitus (J Kor Soc Endocrinol 17:685∼697, 2002).

이동형 라이다의 트레일러 설계

이주희,김경훈,이용우 慶熙大學校 레이저 工學硏究所 1996 레이저공학 Vol.7 No.-

In this paper, we have studied the designs of the trailer and optical devices for the mobile LIDAR used XeCl eximer laser pumped 2-wavelength resonator dye laser. We have designed power generator, optics and sun roof of trailer required for mobile LIDAR, and proposed the specifications of these. At driving and stoping of mobile LIDAR the problems of balance, noise and vibration have resolved, and designed.

다결정 실리콘 태양전지의 상부 전극용 금속 박막 적용

김상수,임동건,이준신,심경석,김홍우,이만근 성균관대학교 1997 학술회의지원논문목록집 Vol.1997 No.-

We investigated grain boundary effect for terrestrial applications of solar cells with low cost, large area, and high efficiency. Grain boundaries are known as potential barriers and recombination centers for the photo generated charge carriers, which make it difficult to achieve a high efficiency cell. To reduce these effects of grain boundarues, we investigated various influencing factors such as thermal treatments various grid patterns selective wet etchings for grain boundarues, buried contact metallizations along grain boundaries, and use of metallic thin films. From the various grid patterns we learned that the series resistance of solar cell reduced open circuit voltage and consequently decreased the cell efficiency. This paper describes the effect of various grid patterns and the employment of metallic thin films for a top electrode.

열공형과 비열공형 피질하 혈관성 치매에서 위험인자의 차이에 관한 비교 연구

배희준,정지향,유경호,나덕렬,김상윤,최경규,양동원,손의주,이상도,김재우,박경원,김응규,이재홍,박미영,한일우,함동석,최문성,하충건,최성혜,이애영,이병철,한설희 대한치매학회 2003 Dementia and Neurocognitive Disorders Vol.2 No.2

Backgrounds and Objectives: Vascular dementia is a group of dementing disoders arising from various stroke syndrome. Among these. subcortical ischemic vascular dementia (SIVD) is regarded as a relatively distinct clinical entity. However, MRI patterns of SIVD are not homogenous. In some patients, lacunes are dominant, and in others, subcortical white matter changes are. This study was designed to compare risk factor profiles between SIVD with and without multiple lacunes. Methods: We divided 47 subjects (22 males, mean age. 68 years) recruited from VADAPET (Multicenter Trial For Evaluation Of The Changes In the PET Images Of Subcortical Vascular Dementia Patient) study into two groups one with more than 5 lacunes in deep gray matter (lacune group) and the other with 5 or less(non-lacune group) Clinical characteristics and laboratory findings of two groups were compared. Results: Nineteen of 47 patients (40%) belonged to the lacune group. The lacune and non-lacune groups d d not differ in the following variables: age, hypertension, diabetes mellitus, hyperlipidemia heart disease, history of stroke or TIA, history of trauma or major surgery, family history of hypertension stroke, or dementia, age at diagnosis of dementia, body mass index, white blood cell count, ESR, CRP, fibrinogen, hemoglobin A1C, total cholesterol. LDL cholesterol creatinine, proteinuria, glucosuria, and microhematuria. However, male sex, smoking alcohol. hemoglobin, and HDL cholesterol were possibly associated more with lacune group SIVD than with non-lacune group (p<0 1) Multivariate analyses revealed that smoking, hemoglobin, and HDL cholesterol were independent predictors of SIVD with multiple lacunes Conclusion: Our study suggests that SIVD with multiple lacunes may be significantly different in smoking habits hemoglobin, and HDL cholesterol from SIVD without multiple lacunes.

Short term life style modification can improve fatty liver in donor candidates

Kyung Chul Yoon,Kwang-Woong Lee,Ok-Kyung Kim,Sanghee Song,Suk Kyun Hong,Sung-Woo Ahn,Hyo-Sin Kim,Jin Yong Choi,Hyeyoung Kim,Nam-Joon Yi,Kyung-Suk Suh 한국간담췌외과학회 2016 한국간담췌외과학회 학술대회지 Vol.2016 No.4

PE-137: Short Term Life Style Modification Can Improve Fatty Liver in Donor Candidates

( Kyung Chul Yoon ),( Kwang-woong Lee ),( Ok-kyung Kim ),( Sanghee Song ),( Suk Kyun Hong ),( Sung-woo Ahn ),( Hyo-sin Kim ),( Jin Yong Choi ),( Hyeyoung Kim ),( Nam-joon Yi ),( Kyung-suk Suh ) 대한간학회 2016 춘·추계 학술대회 (KASL) Vol.2016 No.1

Purpose: It has been known that mild fatty liver grafts (<30%) do not have a significant impact on liver function and liver regeneration. However, NAFLD is related NASH and its general incidence has been reported upto 50% in general population. To reduce both donor and recipient``s risk, we have considered the donor``s liver with even mild fat fraction and inflammatory changes in preoperative liver biopsy. Methods: MRI is used for the decision for undergoing a biopsy and measuring of fat fraction. Even though fat fraction is mild, if it is greater than 5-10%, biopsy is undertaken considering the donor``s age and GRWR, the recipient``s liver function, and emergency status to check for NAFLD, NASH. If the above results are mild and the recipient``s status is not an emergency, we encouraged the donor to exercise. Follow up MRI and biopsy was done to check the changes in fat fraction and once again the recipient``s emergency status was checked to decide whether or not to proceed with the surgery. Moderate or severe degree of fat fraction were determined to be unsuitable for donation. Results: A total of 776 patients underwent donor workup for 588 patients waiting for liver transplantation between July of 2011 and June of 2015. A total of 65 patients had more than 5% fatty liver in CT or MRI, and from the 65 patients 19 patients had moderate to severe fatty liver and were determined to be unsuitable for donation. Out of the 45 patients who had mild fatty liver 13 patients`` biopsy showed more than 10% macrovesicular change and we encouraged life style modification for those 13 patients. Except only one patient, 12 patients were improved their fat fraction and biopsy result. About 45 to 119 days of life style modification by diet and exercise. these patients lost an average of 5.2 kg. Macrovesicular fatty change was reduced from 10-35% to 0-10% of these patients. Weight loss resulted mostly in reduction of macrovesicular change and also in reduction of inflammatory, fibrotic changes. Conclusion: In most of these patients about 2 to 3 months of life style modification resulting in weight loss lowered the fat fraction and changes of inflammation, fibrosis. Thus, it is important to educate and prepare the patients who are preparing for liver donation for liver transplantation.