탈북자의 실업과 빈부격차에 의한 갈등 및 대책 : 탈북자들의 경제문제에 관한 설문조사 결과를 중심으로

강태규,윤덕룡 연세대학교 통일연구원 1997 통일연구 Vol.1 No.2

Fabrication and High-Temperature Compressive Behavior of Unique Multi-Sheet Stacked Block Ni–Cr–Al Metallic Foam

Kyu‑Sik Kim,Tae‑Hoon Kang,박만호,Kee‑Ahn Lee 대한금속·재료학회 2021 METALS AND MATERIALS International Vol.27 No.5

Large unique block Ni–Cr–Al superalloy foam was fabricated using a combination method of powder-alloying, multi-sheetstacking, and hot compression processes. Subsequently, the compressive properties and deformation behaviors of multi-sheetstacked block metallic foam were investigated from room temperature to 1073 K. The analysis of the resulting structuralcharacteristics of the block foam showed that the interfaces between the sheets have complex strut interactions, such ascontacted (deformed) and intersected struts. The relative density was measured as 2.93% for sheet foam and 4.90% for blockfoam. The compressive deformation of sheet and block Ni–Cr–Al foams showed the typical compressive stress–strain curvesof plastically deformable metallic foams regardless of foam type. However, different deformation behaviors in the plateauregions were detected based on the type of foam. It is noteworthy that the yield strength of block foam showed a relativelylower value than that of sheet foam, even though the block foam had higher relative density. The existence of unique interfacesin the multi-sheet stacked block foam may have affected strength and plastic deformation. Finally, distinct compressivebehaviors related to the structural and microstructural characteristics of block Ni–Cr–Al foam are discussed.

Gymnema산이 췌장도의 Beta-세포에 미치는 영향

강주섭,서대규,김수조 한양대학교 의과대학 1991 한양의대 학술지 Vol.11 No.2

The present study was undertaken to investigate the effect of gymnemic acid(GA) on the ultrastructure as well as cellularity of β-cell in the pancreas of rats(N=12). Also studied was the effect of GA on the serum insulin and blood glucose levels during intravenous glucose tolerance test(IVGTT) in man(N=10). Healty adult male rats(Wistar strain) weighing around 200 gm were divided into the three groups; the control, 500mg-GA, and 800mg-GA groups. GA was administered orally 3 times daily for 14 days. All experimental animals were given food and water ad labitum and were sacrificed at 15th day after the administeration of GA and starved for 24 hours before sacrificing them. The specimens obtained from the pancreatic tissues were fixed in 10% neutral formalin for 18 hours at 4℃. After embedding in paraffin, the specimens were sectioned with microtome to a theckness of 6mm. For observing the cellularity of β-cell in the pancreatic islets, Gomori's stain was performed. For studying the ultradtructural changes in pancreatic β-cell, pancreas specimens of 1m㎥ size were prefixed in 2.0% glutaraldehyde-2.5% parpformaldehyde phosphate buffer solution(pH7.2) and post-fixed in the 1% osmic acid. After specimens were dehydrated and embedded in the Epon 802, sectioned by ultramicrotome(HT-2, Sorvall Porter-Blum, USA) to a thickness of 600Å, and stained with uranyl acetate and lead citrate by double contrast method. And these preparations were observed with electron microscope (Hitachi H-600). In IVGTT with or without oral GA(15mg), the subjects were fasted for 12 hours before glucose loading(20ml of 25% glucose solution). The blood glucose and serum insulin level were determined respectively by Glucoscot GT-4301 and EIA(enzyme immunoassay)-insulin kit "Insulotek Mochida" before and at 30, 60, 90 and 120 minutes after glucose loading. The results obtained were as follows: 1. In GA(500 mg/kg & 800 mg/kg) treated rats, the cellularity of β-cell throught the pancreatic islets were markedly increased. 2. The insulin secretoty granuled with or without dense core increased in the 500mg-GA group, and the similar changes were obtained in the 800mg-GA group. 3. Following glucose loading, blood sugar level of normal subject elevated from 80.7±2.7 mg/dl to 163.2±15.9mg/dl in 60min. On the other hand, blood glucose level increased from 78.0±2.9mg/dl to 152.1±10.7mg/dl in 30 min after simultaneous administration of glucose and GA. 4. In the IVGTT the serum insulin concentration rose from the basal level of 7.1±1.4 mU/ml to 74.8 15.5 mU/ml while it elevated from 7.4±1.4mU/ml to maximal level of 113.9±33.1 mU/ml in the IVGATT with oral GA. Consequently, it is suggested that gymnemic acid has the direct simulatory effects on the insulin production and secretion of the pancreatci β-cell, and therfore it may be useful for the therapy or prevention of diabetes mellitus.

복막유착의 원인 규명과 예방을 위한 실험적 연구

강대영,송규상,노승무,조준식,이태용 충남대학교 의과대학 지역사회의학연구소 1999 충남의대잡지 Vol.26 No.1

Postoperative peritoneal adhesion is the most common cause of intestinal obstruction, and intestinal obstruction is one of the most difficult problems in abdominal surgery. In this experimental study for developing peritoneal adhesion model and its prevention, we divided rats into 5 groups; the talc powder treated group, the cotton-fluff treated group, the talc+fluff treated group, the ischemia group and the control group. There were 16 rats in each group. We made incisions on the midabdomen of the rats and administered talc powder, cotton fluff and talc powder+fluff into the peritoneal cavity respectively. In the ischemia group, we clamped the root of superior mesenteric artery for two minutes to induce ischemia on the small bowel of the rat. We counted the number of the peritoneal adhesive sites in peritoneal cavity on the 7th, 14th , 21st and 42nd postoperative day after peritoneal adhesion induced operation, and observed the characters of the adhesion state. The average number of the peritoneal adhesions were 1.25 per one rat in the talc powder group, 1.44 in the fluff group, 1.31 in the talc+fluff group and 1.31 in the ischemia group compared with 0.94 per one rat in the control group performed sham operation. 91.6% of the all adhesions were observed on the peritoneum of the previous incision sites and only 8.4% of the adhesions were adhered to the peritoneal surface of non-incision sites. The data of this study suggest that peritoneal injury and inflammatory reaction is the major cause of peritoneal adhesion. Also this study indicates that foreign bodies can develop peritoneal adhesion, but the effect is much lower than that of peritoneal injury with inflammatoty reaction.

Cd_xZn_(1-x)Te 단결정을 이용한 초고속 THz 전자파의 emitter 특성연구 (Ⅲ)

강현식,정길환,김태규,이해익 전북대학교 과학교육연구소 2002 과학과 과학교육 논문지 Vol.27 No.-

Cd_xZn_1-xTe single crystal system is most ideal crystal for ultrawere investigated for ultrafast T-ray emitters, with composition ratio x=0.00, 0.05, 0.10, 0.15, 0.20, and 0.25. We have found that Cd_0.05Zn_0.95Te crystals are best emitters for T-ray generation, also for above all composition ratio x=0.05 crystals, T-ray emitting ability depended on resitivity were investigated. The results is that the crystals greater than 100Ω-㎝ are good emitters. We study on the Azumuthal angle dependence of the (110) plane and could be explane the 3fold symmetric variation of signals. Finally we could show the linearity is above the 10^5.

독성물질의 세포사 기전 및 세포사 유발물질의 검색법 개발에 관한 연구(Ⅰ) : 독성물질로 인한 파킨슨병 모델에서의 세포사 기전 연구 Study on the cell-death mechanisms of toxin-induced parkinsonism

강태석,김종민,서경원,김영옥,김준규,오재호,이윤동,김규봉,오정자,송연정,임종준,전범석,문전옥,최광식 식품의약품안전청 2000 식품의약품안전청 연보 Vol.4 No.-

MPTP 독성물질이 도파민성 신경세포에 선택적으로 작용하여 산화성 손상에 의한 신경세포사를 일으키는 것을 이용하여 파킨슨병의 동물모델을 만들고, 이를 통해서 아폼토시스를 비롯한 포사의 기전에 대한 연구 및 너코틴의 신경세포 보호효과 여부를 판정하는 실험을 병행하고자 하였다. 파킨슨꾐의 동물모델을 MPTf 독성 물질을 이용하여 확립하였으며, MPTP(30mgag, i.p.)를 투여한 후 1, 2,3, 4, 5일째 흑질 조직을 채춰하여 tarm로 박걸하여 tyrosine hydroxylase 면역조직화학염색을 수행하여 cell countif우한 결과, control은 57.635ce11s, 1일째 친.OfDells,2일째 57.9±6cells,3일릴 없.3±죠ells, 4일째 49.0츠3cells, 5일째 39.4±Scells료 4, 3일째 뚜렷한 신경세포 수의 감소를 보였다. 신경세포사 기전 규명을 위한 아폼토시스 분걱에서는 벼PTP 투여 후 1, 2, 3, 4, 5일째 조직을 채취하여 Hoechst staining, TUNEL staining을 수곡하였는데 양성 반응을 보인 신경세포는 관찰되지 않아. 아폼토시스로 인한 세포사가 관찰되지 않았다. bIPTP 파킨슨병 동물모델에서 nicotine 보호효과 탐색에 관한 실험은 nicat푸e 0.2mgAg을 5일 퐁안 투여 후 리『fP(30mgag)를 CS7Bt/6 마은스에 복강 내주사로 nicotine과 병용 투여한 후 1, 2, 3, 4, 5일째 뇌를 적출하땄다. 신경세포사가 뚜렷이 관찰되기 시작하는 4, 5일째의 신경세포 수의 감소 정도를 20. 30% 정도 약화시키는 경향을 보였으나, nicotine 보호효과에 대한 추가 실헝이 현재 수행 중에 있다. The cause of Parkinson's disease (PD) is largely unknown. However, free radical toxicit? may plaf a role ip. the degeneration of substantia nigra, which is the Hajorfocus of pathological damages in PD. Recently, a neuroprotective effect of nicotine in PD has been suggested. Therefore, the mechanism of neurodegenerafion and protective potential o( nicotine in PD were investigated in the experimental modeB of Pll using a neurotoxin, C57BL/6mice were administered with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP, 30 mg/kg,j.p.). The degree of neurodegenerafion was determined by immunohistochemical stainiHB oftyrosine hydroxylase (TH). TH-positive cells on nigral sections were found 56.0 ±4, 57.9 ±6,52.315ce11s, 49.0±3cells, and 39,4±Scells at days 1, 2, 3, 4, 5, respectively (controls : 57.6±Scells). Hoechst and TUNEL staining showed no evidence of apoptosis. The exandnation on themice co-adrunistered with nicotine(0.2mgAg) and MPTP(30mgag) revealed a tendency ofnicotine protective effects. At days 4 and 5, the degree of TH-positive cells was decreased by20-30%, In corclusiffn, the role of apoptosis was not evidenced in this MPTP modeB of PB.The possible proteccon by nicotine should be elucidated with further studies.

Splitter 급전 2소자 원편파 사각 패치 배열안테나의 설계

손태호,강상규,이병수,이용창,백경훈 순천향대학교 부설 산업기술연구소 2001 순천향 산업기술연구소논문집 Vol.7 No.2

Dual-fed circulary polarized microstrip 1 by 2 array antenna is designed and fabricated. To have circular polarization, we applied power splitter with 90 degree phase shifter by the length exetension. A 1 by 2 uniformed array antenna was designed and measured, and compared with theoretical values. The bandwidth characteristic is well coincided with the designed valued, but the center frequency for the GPS 1.575GHz differed sligthly by the reason of the substrate tolerance.

영역 분리 및 합성법을 이용한 영상 분할에 관한 연구

박규태,최원호,강현철 연세대학교 산업기술연구소 1985 논문집 Vol.17 No.2

This study describes an image segmentation method using a region split-and-merge algorithm. An input image has the resolution of 128 by 128 with 256 grey levels. The algorithm consists of initial segmentation using quad tree structure, region merging, region splitting. formation of region adjacency graph, and small region elimination. These are carried out one after another. Using the concept of MILP(Mapping In the Larger Picture), different threshold values are applied to analyze the characteristics of the algorithm. Edges and vertexes are extracted as the results of image segmentation process. Region adjacency matrix, boundary list and vertex list are obtained from the algorithm. The images of polygonal objects used in this study are obtained by a CCTV camera and a digitizer. Program is written in the 8088 assembly language on an IBM personal computer.

전기화학법에 의해 형성된 Ti 양극산화피막의 특성

김태영,손원우,권태엽,강인규,김교한 大韓齒科器材學會 2002 대한치과재료학회지 Vol.29 No.3

The effects of electrolyte concentration and current density on the behaviour of volt-time curve of the anodizing, morphology, roughness, crystallinity and composition of the oxide layer were studied. Microstructural morphology, crystallinity, composition and surface roughness of oxide layer were analyzed by observed by scanning electron microscopy(SEM) and X-ray diffractometry(XRD), Energy-dispersive spectrometer(EDS), Electron Probe Micro Analyzer(EPMA)and roughness tester, respectively. The results of this study showed that the voltage incresed as the anodizing time increase. The growth of the oxide film developed a barrier layer to a pore-like layer with an increasing of current density, arising a spark discharge. On the morphology of anodic oxide layer the number and size of porosity was increased by increasing anodizing time at a constant concentration of electrolyte. The size of porosity and the roughness of the anodic oxide layer were increased by the increasing of concentration of electrolyte. The anodic oxide layer obtained in the conditions of this experiment was identified as anatase. The crystallinity of oxide layer was decreased by increasing the concentration of electrolyte at constant current density, and increased by the increasing current density at constant electrolyte concentration. In the EPMA analysis of anodic oxide layer, the concentration of phosphorous was increasing the electrolyte concentration and increasing the final voltage at constant electrolyte concentration, The ratio of O/Ti of the oxide layer obtained in this experiment was near 2 confirming this oxide layer was TiO₂

흰쥐에서의 Puromycin Aminonucleoside-유발 단백뇨에 대한 선택적 Thromboxane A₂수용체길항제, KT2-962의 효과

서대규,신인철,고현철,하경란,강주섭 한양대학교 의과대학 1994 한양의대 학술지 Vol.14 No.1

The administration of puromycin aminonucleoside(PAN) to rats caused to nephrotic syndrome which characterized ascites, proteinurisa, hypoalbuminemia, and hyperlipidemia similar to those observed in human minimal change disease. Recently, several studies indicate that renal endogenous thromboxane(Tx) A₂may have an important role in pathophysiology of various renal disease. In this sutdy, we hafve examined the protective effct of a selective TxA₂receptor antagonist, KT2-962(KT2) on PAN-induced proteinuria in rats. Thus, male Wistar rats were given either daily subsutaneous injection of PAN, 20mg/kg, for 10 consecutive days from 3 days before to 7 days with PAN treatment. Urine was collectd, and body weight was measured in interval of 2 days during 2 weeks and urinary N-acetyl-β-Dglucosaminidase(NAG) activity as an index of renal tubular cell damage and urine protein were measured. In addition to measuring BUN, serum creatinine and creatinine clearance were measured to assess the degree of renal functional damage in 14th day. The results(Means SE) otained can be summarized as follows: 1)Body weight(gm) was progressively increased and gained about 46.4gm and 39.2gm on 2 weeks of treatment in the control and KT2 groups respectively. In constrast, there was weight loss about 27.4gm in the PAN group. But, it was increased about 23.2 gm in KT2+PAN grou and means that KT2 has significantly(p<0.05) suppressed weight loss by PAN. 2)Urine flow (ml/24 hours) was slightly increased in both control and KT2 groups during 2 weeks. But, it was significantly(p<0.05) increased after 7th groups during 2 weeks. But, it was significantly(p<0.05) increased after 7th day. But, concurrent administration of KT2 significantly(P<0.05) suppressed PAN-induced polyuria in KT2+PAN group. 3)Urinary protein(mg/24 hours0 was slightly increased in both control and KT2 groups. But, it was progressively increased and reached at the maximal level, 3.2 folds of initial level to 11th day and thereafter slightly reduced proteinuria to 14th day in the PAN group. In contrast, KT2 cotreatment with PAN was significantly(P<0.05) suppressed PAN-induced proteinuria in the KT2+PAN group. 4)Urinary NAG activity was markedly increased and reached to maximal level, 122.03 18.53 U/mg of urine creatinine, 12.7 folds of initial by day 9 and thenafter progressively decreased to 5.4 folds of initial level by day 14 in the PAN group. But, when KT2 was administered with PAN, it was significantly depressed its increment to day 13. But, it was reached to maximal level, 99.05 42.55, 12.7 folds of inital level much than PAN group. This result indicated that KT2 had a partial preventive effect on PAn-induced renal tubular cell damage. 5)The BUN and serum creatinine level(mg/dl) were significantly(p<0.05) increased from initial level, 18.48 1.28 and 0.50 0.03 to 118.42 41.34 and 1.66 0.27 respectively, and creatinine clearance(ml/min) was significantly(P<0.05) decreased from initial level, 0.44 0.02 to 0.28 0.07 by day 14 by PAN treatment. But, when PAN was given together with KT2, the increment of BUN and serum creatinine except for creatinine clearance were significantly(P<0.05) inhibited in the KT2+PAN group. Based on all these results obtained in this study, it is concluded that the coadministration of KT2-962 with PAN can be ingibited protein excretion in urine and suggested that endogenous TxA₂would take part in PAN-induced proteinuria in rats.