재생골재 콘크리트의 수축균열 특성에 관한 연구

구봉근,라재웅,이재범,류연종,이현석 충북대학교 건설기술연구소 2003 建設技術論文集 Vol.22 No.2

As concrete is prevented from shrinking freely, tensile stresses develop which frequently result in cracking. Cracks in reinforced concrete structures reduce overall durability by allowing the penetration of water and aggressive agents, thereby accelerating the deterioration of the reinforcing steel. Highway pavement, bridge decks, and industrial floors are especially susceptible to this type of deterioration since these structures exhibit high rates of shrinkage and are frequently exposed to aggressive environmental conditions. The objectives of this investigation included the implement of experimental procedures for assessing shrinkage cracking behavior on recycled aggregate concrete, the selection of replacement rate and mix composition on recycled aggregate concrete. Specifically, the influence of a shrinkage reducing admixture(SRA) and recycled aggregate concrete was investigated. The shrinkage reducing admixture substantially reduces free, shrinkage and restrained shrinkage cracking while providing similar mechanical properties. Restrained shrinkage experiments were developed and shrinkage cracking was shown to be size dependent and recycled aggregate replacement rate. A mechanical properties experiment approach was developed to predict the behavior of a variety of recycled aggregate concrete specimens. This experimentally approach was used to successfully explain experimental results from a variety of mixture compositions and recycled aggregate concrete. This experiment was used to demonstrate the influence of material and structural properties on the potential for cracking.

Telomere의 기능 손실에 의한 Telomerase 결핍 세포의 성장 억제에 대한 연구

주연진,박정은,전경미,김창민,김상훈,박원봉,이기호 대한암예방학회 2002 Journal of cancer prevention Vol.7 No.3

한국인 성인의 교근 두께에 관한 초음파검사적 연구

이연희,차봉근,박인우 대한치과교정학회 2001 대한치과교정학회지 Vol.31 No.2

일반적으로 골의 형태와 구조는 부착 근육의 활성과 밀접한 관련이 있다고 알려져 있으며,특히 악안면 형태와 저작근 기능과의 관계는 많은 임상 및 동물 실험을 통해 연구되어 왔다. 초음파검사는 임상적 적용이 용이하고 비용이 저렴할 뿐만 아니라 환자에 대한 유해성이 적어 의학분야의 여러 영역에서 널리 이용되고 있다. 이 연구의 목적은 교근의 두께와 악안면 골격 형태와의 상관성을 평가하는 것으로, 강릉대학교 치과대학 남학생 35명과 여학생 15명을 대상으로 하였다. 교근의 두께 측정에는 7.57MHz의 고해상도 직선 탐촉자에 의한 초음파진단장치가 사용되었고, 악안면 골격 형태의 결정은 측방 두부계측방사선사진 분석을 통해 이루어졌다. 이상의 계측치로부터 얻어진 결론은 다음과 같다. 1.남자에서 교근의 평균 두께는 안정 상태에서는 13.8±1.71mm,최대 교합 상태에서 14.8±1.77mm였으며 여자에서는 안정 상태에서 11.6±1.58mm, 최대 교합 상태에서 12.4±1.47mm로 나타났다. 2.교근의 두께는 남녀모두 안정 상태보다 최대 교합 상태에서 유의하게 증가하였다(P<0.05). 3.교근의 두께는 안정 상태와 최대 교합 상태 모두에서 남자가 여자보다 유의하게 두꺼웠다(P<0.05). 4.교근의 두께는 남자에서 안정 상태와 최대 교합 상태 모두 하악평면각과는 음의 상관 관계가 있고 하악지 고경, 전두개저 길이와는 양의 상관 관계가 있음을 알 수 있었다(P<0.05). 5.여자에서는 교근 두께와 유의한 상관 관계가 있는 두부계측방사선사진 분석 항목을 찾을 수 없었다(P<0.05), 이로써 초음파검사는 악골 근육의 기능을 평가하는 전통적인 방법에 대해 추가적인 정보를 제공해 줄 수 있을 것으로 사료된다. It is widely accepted that the shape and structure of bone are closely related to the activity of attached muscle. Numerous clinical and animal experimental studies indicated the significant effects of masticatory muscle function on maxillofacial mofhology. Recently, the development of ultrasonography has spread throughout different fields of medicine. In the clinical examinations, ultrasonography is a convenient, inexpensive technique to apply with accurate and reliable results. The aim of this study is to assess the thickness of the masseter muscle and its correlation to maxillofacial skeleton by examining 35 male and 15 female dental students at Kangnung National University. The masseter muscle thickness of the subjects were measured by ultrasonographic scanning with a 7.5MHz linear probe, and their maxillofacial morphology were investigated by lateral cephalometric radiographs. The relationship between the masseter muscle thickness and maxillofacial morphology of normal adult was statistically analyzed, and the following results were obtained. 1.The average thickness of male masseter muscle was 13.8± 1.71mm in the relaxed state and 14.8 ± 1.77mm at maximal clenching state, while that of female was 11.6±1.58mm and 12.4±1.47mm, respectively. Ethnic difference in thickness of the masseter muscle and maxillofacial skeleton was found when the results of many researchers were compared with those of this study. 2.The thickness of the masseter muscle in both sexes increased significantly at maximal clenching state than in relaxed state(P<0.05). 3.The masseter muscle thickness of male was greater than that of female both in the relaxed state and maximal clenching states(P<0.05). 4.In males, the thickness of the masseter muscle was negatively correlated with the mandibular plane angle and positively correlated wish the mandibular ramus height and antenor cranial base length(P<0.05). It may suggest that the male with thicker masseter muscle has smaller facial divergence. 5.No significant correlation was found between the masseter muscle thickness and maxillofacial morphology in females(P<0.05). Therefore, these data suggest that ultrasonography can add valuable information to the conventional examinations of masseter muscle function.

펄스 변압기를 이용한 비접지 MOSFET의 게이트 구동 회로 설계

박종연,이봉진 江原大學校 産業技術硏究所 2007 産業技術硏究 Vol.27 No.B

This paper presents the new design method for the gate driver circuit of the floating MOSFET by using the pulse transformer. Each parameters of the proposed circuit are delivered by the numerical calculation method. By considering inner characteristics of MOSFET, the gate driver makes to increase the efficiency of the power conversion and decrease operating heat. Computer simulations and to experimental results for a Buck Converter are presented in order to validate the proposed method.

ABC에 의한 마케팅 豫算 시스템에 대한 硏究

李鳳連,柳秀姃 혜전대학 1999 出版文化硏究所論文集 Vol.1 No.-

Many firms use broad strategic approaches for estimating cash flows that are not closely tied to detailed tactical assumptions about future operations. These forecasts may not be very reliable because cash flow projections of new products can have a 30% to 40% margin of errors. Using ABC for marketing budgeting ,which has been definrd as providing economic information for management decision making. ABC model (with benchmarking)forecasted business processes, activities, revenues, operating costs. The ABC analysis provided an understading of projected business processes and activities that allowed senior management to have more confidence in the detailed tactical ABC forecasts, rather than the initial , broad strategic forecasts. ABC system is not only an accounting system but also a management information system that helps manager gain competitive advantage in strategic decision-making process. And through the analysis of company's activities, every employee would understand the company in terms of process. So, reliability of the company's cost information through ABC system enables organization members to focus on the responsibility accounting system. This pro forma ABC approach also is logical next step for companies currently using ABC and benchmarking to understand existing business processes and activities.

산업폐기물인 제강 슬래그쇄석을 사용한 콘크리트의 역학적 특성

이봉학,홍창우,김정태,김연경 강원대학교 석재복합신소재제품연구센터 1997 석재연 논문집 Vol.2 No.-

제강슬래그는 환경오염 방지와 에너지 절감 효과를 얻을 수 있는 콘크리트로 재활용 될 수 있다. 반요인실험법을 사용하여 제강슬래그를 굵은골재에 일정한 비율로 혼입한 콘크리트의 최적배합설계 제시를 위한 예비 실험에서 제강슬래그의 굵은골재 혼입율, 물-시멘트비, 잔골재율, 슬럼프와 같은 주요 변수와 변수 사이의 2차 상관관계를 파악하였다. 예비실험을 한 결과 제강슬래그를 굵은골재로 100%까지 혼입했을 때 제강슬래그를 혼입한 콘크리트의 강도 발현에 가장 변수는 물-시멘트비로 분석되었고, 제강슬래그의 굵은골재 혼입율은 강도 발현에 가장 중요한 변수는 물-시멘트비로 분석되었고, 제강슬래그의 굵은골재 혼입율은 강도 발현에 거의 영향이 없는 것으로 분석되어 제강슬래그를 콘크리트의 굵은골재로 대체할 수 있다는 것을 알게 되었다. 변수 사이의 2차 상관관계에서는 제강슬래그의 굵은골재 혼입율과 잔골재율의 상관관계가 콘크리트의 강도 발현에 가장 큰 영향을 미치는 것으로 나타났다. 목표압축강도를 만족하는 제강슬래그를 혼입한 콘크리트의 최적배합설계는 제강슬래그의 굵은골재 혼입율, 물-시멘트비, 잔골재율에 관하여 제시하였다. An experimental study os performed to examine the feasibility of using wastes steel furnace slag consturction materials and its utility as a replacement for the natural resources to prevent the economic loss was investigated. A half factorial exprements was performed with the variables of W/C ratio, S/A, Coarse aggrigate/Slag ratio and slump as a preliminary study for optimum mix design of concrete. The results show that the W/C ratio and Slump ratio are the most important factor to the concrete strength. The substitute of waste Slag up to 100% has little infleunce, saying that it can substitute te coarse aggregate without damaging the concrete properties.

총 비골 신경마비의 전기진단학적 고찰

윤승호,김은이,김봉옥 충남대학교 의과대학 지역사회의학연구소 1989 충남의대잡지 Vol.16 No.2

Common peroneal nerve palsy is one of the most frequently encountered nerve injuries. The reason for this is the superficial portion of the nerve as it curves around the head of the fibula where it is subject to direct trauma, pressure, or other injuries. In acute stage, when clinical paralysis appears to be complete, electrophysiologic studies are useful guides to predict prognosis. In many of incomplete clinical recovery, the degree of recovery is dependent on rather EMG findings and motor nerve conduction velocities than clinical findings. A retrospective analysis of clinical and electrodiagnostic findings of the 19 cases of common peroneal nerve palsy with follow up seen from January 1987 to August 1989 in the Department of Rehabilitation Medicine at Chungnam National University Hospital was carried out. The results of these studies were as follows. 1. Among the common peroneal nerve injuries, ones accompained by trauma, especially fracture showed relatively poor clinical recovery and ones with compression or spontaneous onset showed better recovery. 2. The clinical recovery was relatively poor when the conduction velocity distal to the fibular head was delayed or when the compound muscle action potential was not obtained over extensor digitorum brevis in the initial motor conduction studies. 3. The clinical recovery was relatively better when the initial sensory conduction studies showed normal sensory distal latency, while the recovery was worse when the sensory nrve action potential was absent or the amplitude was smaller than 50% of that of the non-paralyzed contralateral side.

볶음보리 추출물의 아질산염 소거인자

도정룡,김선봉,이용우,구연숙,박영호 한국노화학회 1991 한국노화학회지 Vol.1 No.1

대학생의 기본 심폐소생술 교육 평가 : 간호과와 비간호과를 대상으로

이정은,고봉연,이인모,최근명,박신일,안홍기 한국응급구조학회 2003 한국응급구조학회지 Vol.7 No.1

The purpose of this study was to evaluate the accuracy of CPR skills and the satisfaction of CPR Training targeted for college students. Also, this study made comparative study of nursing students and non-nursing students. The sample consisted of 248 students(132 nursing students, 116 non-nursing students). CPR Training was designed by two components which were a lecture and demonstration by one professor and individual practice 표 instructors. As tool of measurement estimation satisfaction of CPR Training questionnaires were developed based on educated contents. The accuracy of CPR skills were checked by SkillReporter CPR training manikin. Collected data were computerized and analyzed by SPSS-WIN program. The results were as follows : 1. The skills of CPR were cardiac compression 92.79 times/min, correct cardiac compression rate 90.85%, ventilation 9.93 times/min. correct ventilation rate 79.34%. 2. The mean of the accuracy of CPR skills were 2.94(SD .87). 3. When errors were analyzed, the highest item was stomach distension(51.2%) of ventilation skills and too little(70.6%) of cardiac compression skills. 4. The mean of the satisfaction of CPR training were 2.87(SD .17), the highest item of the satisfaction of CPR Training was practice. 5. We found significant statistical differences based on the accuracy and the error, non-nursing students were high in correct cardiac compression per minute(t=3.615, p=0...) and ventilation too much(t=4.292, p=.000), nursing students were high in correct ventilation rate(t=-3.885, p=.000) and cardiac compression too shallow) t=-2.842, p=.005).

소 수정란의 공배양 및 동결이 체외발생에 미치는 영향에 관한 연구

이종진,이명헌,남윤이,이만휘,이봉구,김상근 충남대학교 수의과대학 동물의과학연구소 1996 動物醫科學硏究誌 Vol.4 No.-

The studies on the carried out to investigate the effects of co-culture with cumulus cells and oviduct epithelial cells on the in vitro fertilization and cleavage rate of bovine follicular oocytes, and to determine the optimum thawing temperature and equilibration time of frozen bovine embryos and on survival rate and in vitro developmental rate of bovine embryos. The ovaries were obtained from slaughtered Korean native cows. The follicular oocytes were cultured in TCM-199 medium containing 10 IU/㎖의 PMSG(Sigma, USA), 10 IU/㎖의 hCG, 1 ㎍/㎖의 β-estradiol(Sigma, USA) and 10% FCS(Sigma, USA) for 24-48 hrs in incubator with 5% CO_2 in air at 38.5℃ and then matured oocytes were again cultured for 12-18 hrs with motile capacitated sperm by preincubation of heparin. The bovine embryos following dehydration by cryoprotective agents and a various concentrations of sucrose were directly plunged into liquid nitrogen and thawed in 30℃ water. The results are summarized as followes : 1. The in vitro fertilization and in vitro developmental rates of bovine oocytes co-cultured with cumulus cells in TCM-199 media were 75.0%-76.8% and 17.3%-27.6%, respectively. And in-vitro fertilization rates of cumulus-enclosed oocytes(55.4%) were significantly(p<0.05) higher than cumulus-denuded oocytes(23.1%). 2. The in vitro fertilization and in vitro developmental rates of bovine oocytes co-cultured with 1 ×10^4 cells/㎖, 1 ×10^6 cells/㎖, 1 ×10^8 cells/㎖ and 1 ×10^15 cells/㎖ oviduct epithelial cells in TCM-199 media were 74.5%-77.8% and 15.7%-21.2%, respectively. 3. The in-vitro fertilization and in vitro developmental rates of bovine oocytes co-cultured in TCM-199 media containing PMSG, hCG, PMSG + hCG, PMSG + β-estradiol, hCG + β-estradiol 0 to 40 hrs after insemination were 74.0%-77.4% and 18.9% - 23.1, respectively. 4. The survival rates of bovine embryos thawed after rapid freezing in the media containing various kinds of cryoprotective agents added 0.25M and 0.50M sucrose were 14.7% - 35.1% and 17.6% - 31.6%, respectively. The survival rates of bovine embryos thawed after rapid freezing in the freezing media containing a various concentration of sucrose added 1.5M and 2.0M glycerol, 1.5M and 2.0M DMSO, and 1.5M and 2.0M propanediol were 23.5% -31.4% and 20.6% - 34.1%, respectively. 5. The temperature thawed at 30℃ after rapid freezing of bovine embryos resulted in a significantly higher embryos survival rate than did at 20℃ and 35℃. 6. The equilibration time on the survival rates of bovine embryos was attained after short period of time(2.5-5 min.) in the freezing medium higher than ling period of time(10-20min.).