ESPI를 이용한 복합재료 구조물의 결함 검출

김경석,정성균,강진식,장호섭 한국비파괴검사학회 2001 한국비파괴검사학회지 Vol.21 No.3

본 논문에서는 ESPI 시스템을 이용하여 복합재료 구조물의 인위, 자연 결함을 검출하였다. 복합재료 구조물에서의 ESPI의 적용성을 알아보기 위해 복합재료 적층판 시험편, 하니컴 구조물 시험편, 접착조인트 시험편을 사용하였다. 결함을 검출하기 위해 시편의 표면변형을 쉽게 발생시킬 수 있는 열하중법을 선택하였다. 실험경과는 ESPI를 이용하여 복합재료 구조물의 결함을 쉽게 검출할 수 있고, 다른 여러 복합재료 구조물의 결함의 검출에도 적용할 수 있음을 확인하였다. In this paper, artificial and real defects(delamination and debond) in composite structures were detected by using ESPI system. There types of specimens, that is, composite laminates, honeycomb structures, and adhesive joints, were used to study the applicability of ESPI to composite structures. To detect defects in specimens, we selected thermal loading method that can easily induce the surface deformation of specimen. Experimental results show that defects in composite structures could be easily detected by ESPI. Moreover, it shows that ESPI could be usefully applied to the detection of defects of defects in various composite structures.

不正咬合類型에 따른 齒軸傾斜度에 關한 頭部放射線計測學的 硏究

洪性德,車敬石 단국대학교 치의학연구소 1991 논문집 Vol.3 No.-

This research was performed to find out the adaptation patterns of maxillary and mandibular posterior teeth to the changes in relationships of vertical skeletal components, which constitute the skeletofacial complex. For this research, 61 adult malocclusion patients were chosen as subjects according to the Hellman's dental age with normally ranged FMN-A-B angle. These subjects were divided into 4 groups in maxilla and 3 groups in mandible according to mesiodistal inclinations of teeth. Following results were obtained after studying the relationships of the vertical skeletal components between each group. 1. Inspite of the fact that the FMN-A-B angle was within a normal range, the degree of mesiodistal inclinations of maxillary and mandibular posterior teeth showed differences in relation to the anteroposterior relationships of maxilla and mandible. In case where the FMN-A-B angle was large, the mesial inclinations of maxillary posterior teeth showed more increase from the posterior to the anterior, whereas in mandible it showed overall decrease. 2. The degrees of mesial inclinations of mandibular posterior teeth were increased when the angulations of lower facial height, occlusal plane angle and mandibular plane angle were greater. 3. The patterns of mesial inclinations of maxillary posterior teeth were varied according to the angulation of lower facial height. If relatively large, it showed more increase from the posterior to the anterior and it was decreased nearly consistent when the angulation was small. 4. The degrees of mesial inclinations of maxillary posterior teeth were decreased as the lower facial height, palatal plane angle, occlusal plane angle and the mandibular plane angle became greater.

플레이트거더의 전단강도

최취경,김태영,서성연,김정석,김상섭,김규석 대한건축학회 2003 대한건축학회 학술발표대회 논문집 - 계획계/구조계 Vol.23 No.1(구조계)

In the design of plate girder web panels, it is required to evaluate accurately the elastic buckling strength under pure shear. Whether or not the post-buckling strength is accounted for. Currently. Elastic shear buckling coefficients of web panels stiffened by transverse intermediate stiffeners are determined by assuming conservatively that web panels are simply supported at the juncture between the flange and the web. Although the notion of the real boundary condition at the juncture of the web and flanges to be somewhere between simple and fixed has been recognized from early days, the boundary condition has been conservatively assumed. Mainly due to lack of means to evaluate it in a rational manner. In this paper. A series of numerical analyses based on a three-dimensional finite element modeling is carried out to investigate the effects of the geometric parameters on the boundary conditions at the juncture between the flange and the web.

지방자치단체간 인사교류 활성화 방안 : 충청남도의 사례를 중심으로 A Case Study of the Southern Choongchung Province

권경득,김판석,오성호,박경원 한국정책학회 2003 韓國政策學會報 Vol.12 No.4

한국의 지방정부는 행정수요의 변화에 능동적으로 대처하고, 높은 생산성과 세계경쟁력을 갖춘 정부로의 변화를 요청 받고 있다. 특히 지방분권화에 따른 내부역량 강화 차원에서 지방 정부는 인력관리의 효율성 제고와 유연하고 탄력적인 인력관리를 위하여 인력관리 부문의 개혁을 지속적으로 추진하는 과정에 있다. 행정서비스의 효율적인 운영의 주체는 사람이므로 지방정부의 생산성 향상을 위한 지방공무원의 전문화, 능력발전, 인사교류 등 '사람을 다루는 인사관리'가 주요한 개혁과제로 인식되고 있다. 국가적 차원에서 한정된 인적자원을 보다 효율적으로 운영하기 위해서 정부간 또는 정무-민간부문간에 보다 활발한 인적자원 교류의 필요성이 대두되고 있다. 그러나 민선자치단체장 이후 지방정부의 인사교류가 활발하게 이루어 지고 있지 않아 국가 전체적인 측면에서 인력활용의 극대화를 도모하지 못하고 있는 실정이다. 지역할거주의와 자기조직제일주의 그리고 동류집중(inbreeding) 등을 줄이기 위해서는 교류를 촉진해야 한다. 따라서 본 연구의 목적은 지방자치단체간 인사교류의 현황과 문제점을 살펴보고, 지방자치단체간 인사교류의 활성화를 위한 개선방안을 모색하는데 있다. In the last decade, Korea has undergone considerable socio-political change. The Korean citizen is now exercising newly gained democratic freedoms including making demands upon Korean local governments are further compelled to reform systems and practices in order to improve the nation's overall global competitiveness. This paper will argue that the primary focus of improving local governments should be to improve the competencies of human capital. For example, local governments need to improve the efficiency and flexibility of human resource management through professionalization of the work force and structured human resource development including personnel exchanges. In order to promote mobility and flexibility of human resources, this paper examines personnel exchange practices in Korean local governments. There might be various reasons for underdevelopment of personnel exchange in Korea, but one reason for the fact that personnel exchange has not been practiced actively is that since the mid-1990s the chief executive officers of Korean local governments have become elected positions. Therefore, newly elected mayors and governors have been reluctant to deploy their most competent employees to other regions for fear the services upon which their re-election hopes depend might deteriorate. This study first reviews existing problems of personnel exchange in Korean local governments, and then suggests possible policy alternatives in order to promote personnel exchanges between the local governments and even suggest exchanges from other sectors.

不正咬合類型에 따른 齒軸傾斜度에 關한 頭部放射線計測學的 硏究

洪性德,車敬石 대한치과교정학회 1991 대한치과교정학회지 Vol.21 No.3

This research was performed to find out the adaptation patterns of maxillary and mandibular posterior teeth to the changes in relationships of vertical skeletal components, which constitute the skeletofacial complex. For this research, 61 adult malocclusion patients were chosen as subjects according to the Hellman's dental age with normally ranged FMN-A-B angle. These subjects were divided into 4 groups in maxilla and 3 groups in mandible according to mesiodistal inclinations of teeth. Following results were obtained after studying the relationships of the vertical skeletal components between each group. 1. Inspite of the fact that the FMN-A-B angle was within a normal range, the degree of mesiodistal inclinations of maxillary and mandibular posterior teeth showed differences in relation to the anteroposterior relationships of maxilla and mandible. In case where the FMN-A-B angle was large, the mesial inclinations of maxillary posterior teeth showed more increase from the posterior to the anterior, whereas in mandible it showed overall decrease. 2. The degrees of mesial inclinations of mandibular posterior teeth were increased when the angulations of lower facial height, occlusal plane angle and mandibular plane angle were greater. 3. The patterns of mesial inclinations of maxillary posterior teeth were varied according to the angulation of lower facial height. If relatively large, it showed more increase from the posterior to the anterior and it was decreased nearly consistent when the angulation was small. 4. The degrees of mesial inclinations of maxillary posterior teeth were decreased as the lower facial height, palatal plane angle, occlusal plane angle and the mandibular plane angle became greater.

4기통 전기점화기관의 혼합기 불균일 분배가 배기가스에 미치는 영향

진성호,박경석 경희대학교 환경연구소 1993 環境硏究 論文集 Vol.4 No.-

The exhaustion of gasoline engine is related with constitution of mixture, so lean mixture which is for fuel economy should be completely burned as much as possible. But much of supply fuel clings to intake manifold inner wall in a carburetor type engine. Accordingly, it causes nun-uniform mixture and nun-uniform fuel distribution. In this study, variation of fuel air ratio, amount of emission is measured. The effect of fuel film in intake manifold on mixture distribution is studied.

腦硬塞患者의 血壓·脈搏 및 腦血流에 대하여 水溝-承漿穴 電鍼刺戟이 미치는 影響

박성욱,문상관,고창남,조기호,김영석,배형섭,이경섭 경희대학교 1997 慶熙醫學 Vol.13 No.4

Alcaligenes latus의 배양방법에 따른 생분해성 플라스틱의 생산특성

박성연,조강현,최희식,류희욱,조경숙 이화여자대학교 환경문제연구소 1998 이화환경연구 Vol.2 No.-

생장과 동시에 poly(3-hydroxybutyrate, PHB) 를 체내에 축적하고, 값싼 당류인 sucrose를 이용할 수 있는 Alcaligenes latus의 생장과 PHB 생산을 최적화 할 수 있는 배양 조건에 대하여 연구하였다. 균주 생장과 PHB 생산성에 미치는 sucrose의 초기농도의 영향을 5L 발효조를 이용하여 회분식 배양 방법에 의해 조사하였다. PHB생산성은 sucrose농도가 10g/L에서 30g/L로 증가함에 따라 0.11에서 0.36g-PHB/L·h까지 증가하였고, 그 이상의 농도에서는 큰 변화없이 0.36∼0.39g-PHB/L·h에서 일정하게 유지되었다. 균주의 비증식속도는 sucrose 농도 증가함에 따라 증가하여 30g/L에서 최대값 0.44h()을 보였으며, sucrose의 농도가 30g/L을 초과하면 균주의 생장은 기질에 의해 저해 받았다. A. latus를 이용하여 대량으로 PHB를 생산하기 위해 유가식 배양과 반연속 유가식 배양을 수행하였다. 인산염 제한하에서 유가식 배양에 의해 얻은 PHB 생산성은 1.14g-PHB/L·h로, 인산염 제한없는 조건에서 얻은 PHB생산성(2.10g-PHB/L·h)에 비해서 훨씬 작았다. PHB함량은 영양소 제한에 관계없이 55∼60%이었다. 영양소 제한 없이 반연속 유가식 배양법에 의해 PHB생산성을 4.5∼4.8g-PHB/L·h까지 향상시킬 수 있었다. 평균 PHB 함량, 소비된 sucrose당 건조 균체중량 수율 및 PHB 생산 수율은 각각 60%, 0.48 및 0.32이었다. 그러므로, 생장과 동시에 PHB를 축적할 수 있는 A. latus를 이용하여 PHB를 생산할 경우, 반연속 유가식 배양법은 높은 PHB생산성을 얻을 수 있는 유망한 배양법임을 알 수 있다. Optimum conditions for cell growth and poly(3-hydroxybutyrate, PHB) biosynthesis of Alcaligenes latus, which can accumulate PHB simultaneously in associated with cell growth and grows well on a cheap carbon source such as sucrose, were investigated. The effect of initial sucrose concentration, ranged from 10 to 50g/L, on the cell growth and PHB accumulation were studied by a batch culture in a 5L fermentor. PHB productivity was increased from 0.11 to 0.36g-PHB/L·h with increasing sucrose concentration up to 30g/L, and it was fairly constant between concentrations of 30g/L and 50g/L. The maximum specific growth rate, 0.44h(), was obtained at 30g-sucrose/L, and the growth was inhibited at concentrations of sucrose over 30g/L. A. latus was also cultivated to attain high PHB productivity by fed-batch or semicontinuous fed-batch culture techniques. PHB productivity by a fed-batch culture under phosphate limitation(1.14g-PHB/L·h) were smaller than that without nutrient limitation(2.10g-PHB/L·h). but there is no significant difference of PHB content(55∼60%) obtained in both culture. By a semicontinuous fed-batch culture without nutrient limitation, high PHB productivity could be obtained as 4.5∼4.8g-PHB/L·h. The average PHB content, the yield of dry cell weight, and the yield of per consumed sucrose were 60%, 0.48, and 0.32, respectively. These results suggest that the semicontinuous fed-batch culture technique is one of promising methods to achieve high PHB productivity by A. latus.

지속적 및 간헐적 가압력이 치주인대 배양세포의 Alkaline Phosphatase 활성도에 미치는 영향

성재현,경희문,배성민,권숙이 대한치과교정학회 1997 대한치과교정학회지 Vol.27 No.4

지속적 및 간헐적인 가압력이 배양치주인대 세포의 ALP활성도에 미치는 영향을 알아보기 위하여 치주인대세포를 24 well 배양접시에 배양한 후 밀생상태가 되었을 때, 세포배양기 속의 특수제작된 사각상자에 배양접시를 넣은 후 실험기간동안 300g/㎠의 압력을 10분간 가압시킨 후 10분간 가압이 중지되도록 한 간헐적 가압군, 그리고 압력을 가하지 않은 군을 대조군으로 하여 각각 실험 24시간, 72시간 후의 alkaline phosphatase의 활성도를 측정하여 다음과 같은 결과를 얻었다. 1. 가압 24시간 군에서는 간헐적 가압군이 대조군에 비하여 ALP활성도가 낮게 나타났다(p>0.05). 2. 가압 48시간 군에서는 실험군은 대조군에 비하여 ALP활성도에 유의한 차이는 나타나지 않았다. 3. 가압 72시간 군에서는 지속적 가압군이 대조군에 비하여 ALP활성도가 높게 나타났다(p>0.01). The purpose of this study was to evaluate the effect of cellular activity on PDL cells dependent on intermittent and continuous compressive force by determining the alkaline phosphatase activity. An intermittent and continuous compressive force were applied on PDL cells at the confluent stage. The alkaline phosphatase activity was measured on control and experimental groups every 24, 48, 72hours. The experimental group were consist of continuous and intermittent compressive group which were compressed by 300g/㎠ of diaphram pump. The intermittent compressive group was connected by timer which was worked on 10 minutes and off 10minutes. The results were as follows; 1. The alkaline Phosphatase activity of intermittent compressive group was lower than control at 24 hours(p>0.05). 2. The alkaline Phosphatase activity between each groups showed no significant differences at 48hours. 3. The alkaline Phosphatase activity of continuous compressive group was significantly higher than control group at 72 hours(p>0.01).

콘크리트 포장의 플라이애쉬 재활용 방안연구

정영화,최성용,윤경구,용석응,김태경 강원대학교 석재복합신소재제품연구센터 1998 석재연 논문집 Vol.3 No.-

한국 대부분의 고속도로는 콘크리트로 포장되고 있으며, 플라이애쉬를 포장용 콘크리트에서 재활용하면 콘크리트의 성능을 향상시킴과 동시에 경제적 이익과 환경보호에 큰 기여를 할 것이다. 본 연구에서는 플라이애쉬를 포장 콘크리트에 재활용하고자, 플라이애쉬 치환율, 물-시멘트비, 굵은골재 최대치수를 주요실험 변수로 하여 이들이 플라이애쉬를 혼입한 포장용 콘크리트의 역학적 특성에 미치는 영향을 살피기 위해서 실험하여 통계처리 분석하였다. 이러한 분석결과를 바탕으로 포장 콘크리트의 적정배합을 제시하였으며 결과는 다음과 같다. 플라이애쉬를 혼입한 포장콘크리트의 휨강도에 영향을 미치는 인자는 플라이애쉬 치환율이 가장 큰 것으로 나타났으며, 다음으로 굵은골재 최대치수와 물-시멘트비 순으로 영향을 미친다. 또한, 플라이애쉬 치환율과 굵은골재 최대치수의 상관관계가 가장 큰 것을 알 수 있었다. 목표압축강도를 목표 휨강도의 6배로 선택하여 적정구간을 결정하였으나, 적정배합구간이 목표압축강도에 의해서 결정되었다. 이는 플라이애쉬의 작은 수화물이 공극을 효과적으로 채움으로써 휨강도의 증진에 크게 기여하기 때문으로 판단된다. 고속도로 포장에 적용할 수 있는 32mm의 굵은골재 최대치수와 45%의 물-시멘트비를 사용하는 목표 휨강도 45kg/㎠의 적정배합에서는 5.0%까지 플라이애쉬를 치환 가능하고, 50kg/㎠의 적정배합에서는 2.5%까지 치환 가능하다. 공항 포장에 적용할 수 있는 40mm의 굵은골재 최대치수와 37%의 물-시멘트비를 사용하는 목표 휨강도 45kg/㎠의 적정배합에서는 4.5%까지 플라이애쉬를 치환 가능하고, 50kg/㎠의 적정배합에서는 2.0%까지 치환 가능하다. The most of highway in Korea have been paved by concrete since last ten years. The recycling of fly ash in pavement concrete may result in economics, the improvement of concrete quality and the reservation of environment. This paper focused on the series of experiment and statistics analysis with experimental variables such as fly ash substitute ratio, water-cement ratio and maximum size of coarse aggregate in order to investigate the feasibility of recycling of fly ash in pavement concrete, to see the strength characteristics and t propose the optimum mix design based on previous results. The results of experiments and analysis were follows; The fly ash substitute ratio affected most seriously to the flexural strength of concrete among main variables, followed by maximum size of coarse aggregate and water-cement ratio. The interaction between fly ash substitute ratio and coarse aggregate size was the biggest. The optimum mix design was determined by target compressive, which was selected as 6 times of flexural strength. This indicated that the small hydrate of fly ash in concrete filled in effectively and resulted in the enhancement of flexural strength. the optimum mix design for highway pavement concrete with 32mm of maximum size of coarse aggregate and 45% of W/C can incorporate up to 5.0% and 2.5% of fly-ash at 45 kg/cm² and 50 kg/cm² of target flexural strength, respectively. The optimum mix design for airport pavement concrete with 40mm of maximum size of coarse aggregate and 37% of W/C can incorporate up to 4.5% and 2.0% of fly ash at 45 kg/cm² and 50 kg/cm² of target flexural strength, respectively.