유리纖維 補强 콘크리트 流動 特性에 관한 硏究

朴承範,任昌悳,尹義植 忠南大學校 産業技術硏究所 1989 산업기술연구논문집 Vol.4 No.1

Concrete is an excellent structural material, but it has many problems due to brittle behavior, weak resistance in tension, flexibility and toughness. In order to improve these problems, usually fiber reinforced concrete is used. But in the case of GFRC insufficient workability is caused by using glass fiber and there is lack of studying on it. This report of the following concrete of GFRC was experimented by the different W/C, S/A, glass fiber contents and maximum size of Aggregates. The results of this study is as follows; 1) Optimum S/A ratio is 0.6 at the glass fiber contents of from 0.25% to 0.75% in GFRC, but it cannot be obtained optimum S/A ratio at over 0.75. 2) Even though increasing the W/C ratio, we can get more slump, but slump is much more influenced by fiber contents in GFRC rather than increasing the W/C ratio. 3) Workability of GFRC is much more influenced by fiber contents than fiber length. 4) Workability of GFRC is a little improved by the bigger maximum size of aggregates.

All-in-one 접착제에서 초음파진동이 법랑질과 상아질의 결합강도와 레진침투에 미치는 영향

이범의,장기택,이상훈,김종철,한세현 大韓小兒齒科學會 2004 大韓小兒齒科學會誌 Vol.31 No.1

초기의 접착 시스템은 여러 단계의 술식을 필요로 하였으며 술자의 기술과 재료의 성질에 크게 좌우되었으나 최근 산부식, priming, adhesive를 한번에 적용할 수 있는 a11-in-one adhesive system이 등장하였다. 치과에서의 vibration의 이용은 치석의 제거 및 접착제의 점도를 낮추는데 이용되어왔으며 vibration은 접착제의 흐름성을 향상시켜 film thickness를 낮추어 수복물 주위의 미세누출을 줄이는데 도움을 준다. 이에 저자들은 all-in-one adhesive system에서 vibration이 법랑질과 상아질의 접착강도와 레진침투에 미치는 효과를 알아보고자 하였다. 법랑질 시편은 발거 후 실온에서 0.1% thymol 용액에서 보관된 30개의 건전한 사람의 대구치를 무작위로 10개씩 세군으로 나누고 근원심 방향으로 두 부분으로 분리하여 각각은 같은 접착제를 사용하고 초음파진동여부를 다르게 하였고, 아크릴 레진을 이용하여 직경 1-inch의 PVC관에 매몰한 후 협설면이 아크릴봉과 동일한 높이가 되도록 220-, 600-grit 연마지로 순차적으로 연마하였고 군당 10개씩 여섯 군으로 분류하였다. 1군과 2군은 Prompt L-Pop(3M-ESPE, Seefeld, Germany), 3군과 4군은 One-Up Bond F(Tokuyama Corp., Tokyo, Japan). 5군과 6군은 AQ bond(Sun Medical Co., Kyoto, Japan)를 제조사의 지시에 따라 도포하였다. 2군, 4군, 6군은 초음파 치석제거기를 이용하여 치면에 대고 15초간 진동을 가한 후 광중합하였다. 상아질 시편은 치관부 법랑질을 제거한 후 상아질면을 아크릴 봉과 동일한 높이가 되도록 하고 법랑질 시편과 동일하게 처리하였다. 이후 직경 2mm, 높이 3mm의 Teflon mold(Ultradent, U.S.A.)를 이용하여 복합레진을 충전한 후 40초씩 두 번에 나누어 광중합한 후 24시간동안 실온에서 증류수에 보관하였다. 열순환 시행한 후, 만능측정 기(Instron4465)로 전단결합강도를 측정하였으며 Resin tag의 양상을 비교하기 위해 각 군의 시편의 치질을 완전히 용해 시킨 후 표면을 주사전자현미경사진으로 관찰하여 다음과 같은 결과를 얻었다. 1. 법랑질에서 초음파 진동을 가한 군(2,4,6군)은 가하지 않은 군(1,3,5군)에 비해 평균 전단결합강도가 높게 나타났다. 그 차이는 AQ bond 군을 제외하고 통계적으로 유의하였다(p<0.05). 2. 상아질에서 초음파 진동을 가한 군(2,4,6군)은 가하지 않은 군(1,3,5군)에 비해 평균 전단결합강도가 높게 나타났다. 그러나 그 차이는 One-Up Bond F군을 제외하고는 통계적으로 유의한 차이가 없었다. 3. 전자 현미경 관찰에서 초음파 진동을 가한 군에서 더 많은 법랑질의 소실과 상아질에서 resin tag의 길이가 길었고 lateral branch의 수도 많이 관찰되었다. The objective of this study was to apply the vibration technique to reduce the viscosity of bonding adhesives and thereby compare the bond strength and resin penetration in enamel and dentin achieved with those gained using the conventional technique and vibration technique. For enamel specimens, thirty teeth were sectioned mesio-distally. Sectioned two parts were assigned to same adhesive system but different treatment(vibration vs non-vibration) Each specimen was embedded in 1-inch inner diameter PVC pipe with a acrylic resin. The buccal and lingual surfaces were placed so that the tooth and the embedding medium were at the same level. The samples were subsequently polished silicon carbide abrasive papers. Each adhesive system was applied according to its manufacture's instruction. Vibration groups were additionally nitrated for 15 seconds before curing. For dentin specimen, except removing the coronal part and placing occlusal surface at the mold level, the remaining procedures were same as enamel specimen. Resin composite(Z250 3M. U.S.A.) was condensed on to the prepared surface in two increments using a mold kit(Ultradent Inc., U.S.A.) Each increments was light cured for 40 seconds. After 24 hours in tap water at room temperature, the specimens were thermocycled for 1000cycles.. Shear bond strengths were measured with a universal testing machine(Instron 4465, England). To investigate infiltration patterns of adhesive materials, the surface of specimens was examined with scanning electron microscope. The results were as follows : 1. In enamel, the mean values of shear bond strengths in vibration groups(group 2,4,6) were greater than those of non-vibration group(group 1,3,5). The differences were statistically significant except AQ bond group. 2. In dentin, the mean values of shear bond strengths in vibration groups(group 2 4, 6) were greater than those of non-vibration groups(group 1,3,5). But the differences were not statistically significant except One-up Bond F group. 3. The vibration group showed more mineral loss in enamel and longer resin tag and greater number of lateral branches in dentin under SEM examination.

정중과잉치로 인해 회전된 상악 중절치의 치험례

이범의,김영재,김정욱,장기택,이상훈,김종철,한세현 大韓小兒齒科學會 2004 大韓小兒齒科學會誌 Vol.31 No.4

정중과잉치의 원인은 잘 알려지지는 않았지만 dental lamina의 hyperactivity에 의해 발생한다는 가설이 가장 많이 받아들여지고 있다. 이러한 정중과잉치의 병발증으로는 주변 영구절치의 맹출 장애, 만곡 치근, 치근흡수, primordial 혹은 follicular cyst의 형성, 회전, 이환된 부위의 총생 및 비정상적인 정중이개를 일으킬 수 있다. 이러한 이유로 영구전치의 회전이 야기되면 보통 공간의 부족은 적거나 없으며 재발이 흔하므로 과개선이 요구된다. 재발의 방지를 위해서는 조기치료, 과개선, 긴 보정기간, 적절한 접촉면의 형성, 짝힘의 사용, 그리고 수술적인 방법 등이 제안되어왔다. 이에 저자는 정중과잉치로 인하여 심하게 회전된 상악중절치를 주소로 내원한 환아에서 교정적, 외과적 술식을 이용하여 양호한 결과를 얻은 두 증례를 보고하는 바이다. The etiology of mesiodens is unknown but the most widely accepted theory is the hyperactivity of the dental lamina. Complications of mesiodens are delayed or prevented eruption of maxillary central incisors, displacement or rotation of permanent teeth, crowding of affected region, abnormal diastema or permanent space closure, dilaceration or abnormal root development of permanent teeth, primordial or follicular cyst formation, root resorption of adjacent teeth, eruption into nasal cavity. If mesiodens rotate the maxillary central incisors, space deficiency is not common and relapse is very common. So overcorrection is needed. To prevert the rotational relapse, early treatment, overcorrection, long retention period, properly formed proximal surface, use of coupled force, and surgical techniques have been suggested. The authors present two cases, whose chief complain were severely rotated maxillary incisors by mesiodens, treated by orthodontic and surgical technique and showed good results.

골프수요 시차집중률의 구조적 변화 분석 : The East-Coastal Region of Gangwon Province

정의선,최성범 한국스포츠리서치 2004 한국 스포츠 리서치 Vol.15 No.2

This study aims to analyze structural changes of seasonality in golf tourism demand and suggest alternatives on the development of effective demand of golf tourism for the east-coastal region of Gangwon province. The results of the analysis of absolute growth rate and relative composition rate indicated growth, and public golf courses are growing more rapidly than courses for members. National average reveals a stable structure of demand except for January and February, but in the case of the east-coastal region of Gangwon province, peak season barely lasts for May, June, July, August and October. On the basis of the above examination, the author suggests alternatives for attractive tourism destinations in the east-coastal region of Gangwon province. It is required that the central government or local government should establish a induced tourism policy for the creation of effects. strategic de-marketing is necessary, because mass marketing is accompanied with enviornmental pollution, destruction of regional values, magnification of the dependence-oriented economic structure, and so forth. In order to link tourism resources, it is important that the coastal scenery in golf courses is built and the central and local government should develop tourism, leisure and sports belt for visitors and residents.

급냉 응고된 Al-Li-Cu합금의 열처리, 미세조직 및 기계적 성질에 관한 연구(I)

許明日,南勝義,李範圭,羅亨用,金錫胤 弘益大學校 1988 弘大論叢 Vol.20 No.2

Effect of aging condition on the microstructure and hardness properties of Al-3Li, Al-3Li-2Cu, Al-3Li-2Cu-0.3Zr have been studied. The alloy ribbons have been prepared by means of Single Roll Melt Spinning by rapid solidification technique. In rapidly solidified Al-3Li-2Cu, Al-3Li-2Cu-0.3Zr alloy ribbons show the icosahedral intermetallic compound of five-fold symmetry which is placed in cell-bound-ary and matrix. In the matrix precipitated fine δ'(Al₃Li) phase. Heat-treated at 250℃ 1hr. In this condition, δ'(Al₃Li) phase started decompose. The icosahedral intermetallic compound has been grown. When heat-treated at 300℃ 1 hr, the δ' phase has been decomposed all. In the matrix, icosahedral intermetallic compound has been grown greatly. The micro-hardness has been obtained more high Al-Li-Cu-(Zr) alloy than Al-Li alloy. Strength-hardended phenomena showed to solution hardning by the addition of Cu. When the heat-treated at 250℃ 1 hr, in the alloy of Zr addition, delayed decomposed δ' phase. In the case, micro-hardness gradually decreased. When the heat-treatment have done at 300℃ 1 hr, the micro-hardness has been decreased because δ' phase decomposed all.

황색포도구균의 균혈증에서 초기 항생제 치료가 예후에 미치는 영향

김성한,박완범,이기덕,강철인,최영주,김홍빈,박상원,김의석,오명돈,김의종,최강원 대한감염학회 2002 감염 Vol.34 No.5

축력과 모멘트를 받는 가셋트 K형 상관접합부의 강도 추정에 관한 연구

박순정,신의균,김우범,정수영 忠南大學校 産業技術硏究所 1997 산업기술연구논문집 Vol.12 No.2

A numerical analysis and finite element analysis were performed to suggest formula of gusset-tube connection that is subjected to axial and lateral load. Through the finite element analysis, the infulence of parameters on the ultimate strength was estimated and design formula was obtained from the case-study of result of the finite element analysis. The formulas suggested by other authors and the analytical of this paper were compared. The primary parameter of the analysis are axial load, lateral load, thickness of the primary menber, diameter of the primary menber and length of the gusset-plate. It was noted that the strength of connetion by the previous proposed formulas was much differ from result of the finite element analysis, but the difference of result between the proposed formula and the finite element analysis was within thirty percentage range. On the future research, small scale and full scale test will be performed to verify a formula suggested by this paper.

K형 강관접합부의 편심접합에 관한 실험적 연구

김갑순,신의균,김우범,정수영 충남대학교 산업기술연구소 2000 산업기술연구논문집 Vol.15 No.1

A finite element analysis and experimental study were performed to investigate the behavior and strength of a connection of tubular steel member considering slenderness ratio and eccentricity. Primary interest here are ultimate strength of connections having eccentricity. In comparison with the current design standard according to which the gravity axes of the main and branch pipes coincide with each other, the inner eccentric joint where the gravity axes of the branch pipes are shifted to the gusset plate side can reduce the gusset plate size. However, in the eccentric joint where the gravity axes do not coincide, the bending moment that acts on the main pipe due to eccentricity causes a problem. As a result, in cases where the slenderness ratio is 40 or less, the buckling strength of the inner eccentric joint was similar to that of a joint without eccentricity. Therefore the possibility of use of inner eccentricity connection to reduce the gusset plate size has been verified.

X-관련성 만성육아종성질환의 진단을 위한 PMA-activated NBT 검사

김중곤,조한익,오흥범,김의종,최강원 대한감염학회 1996 감염 Vol.28 No.1

목적 : Activated NBT 검사는 만성육아종성질환을 선별하는 검사이다. 활성제로 PMA를 사용하면 X-linked CGD의 경우 보인자를 감별할 수 있다. 방법 : CGD의 가족력을 부인하는 정상인 30명을 대상으로 PMA activated NBT 슬라이드 검사를 실시하여, 정상대조에서의 formazan 형성율을 보았으며, 동일 검사를 CGD가 강력히 의심되는 환자와 그 가족에 대하여 실시하였다. 결과 : 정상대조 30명 전원에서 98% 이상의 formazan 형성세포가 관찰되었다. 환자에게 실시한 결과 세환자 모두에서 0%의 결과를 보였다. 환자의 어머니에서는 각각 57, 70, 67%의 결과를 보였다. 결론 : 본 연구를 통하여 세 환자는 X-관련성 만성육아종성질환이라는 진단을 내릴 수 있었다. PMA activated NBT 슬라이드 검사는 시행하기가 쉽고 재현성이 좋으므로, 어러 검사실에서 소아기 면역결핍증을 선별하는 검사의 하나로 시행되는게 바람직하다고 사료된다. Background : Chronic granulomatous disease(CGD) is uncommon inherited disorder in which phagocytic cells fail to produce antimicrobial superoxide(O₂) due to NADPH oxidase deficiency. This disease can be easily screened by activated nitroblue tetrazolium(NBT) test. In case of X-linked CGD, carriers also can be detected. Methods : PMA(phorbol myristate acetate) activated NBT test was performed as previously described. Test performance was evaluated in 30 normal persons who denied family history mimicking CGD. Test was also applied to the three strongly suspected cases of CGD. Two of the cases were 12 year old boy and 7 year old boy, who suffered from many infectious diseases since 6 month old and 4 month old, respectively. The other remaining case was 22 year old man who suffered from many infectious diseases since 6 year old, but now relatively in health compared to the other two cases. Results : More than 98% formazan formation was observed in all normal controls. No formazan positive cell was shown in all of the three patients. However, applied to the mothers, the test revealed 57%, 70%, 67% positive cells, respectively. Conclusion:X-linked transmission of CGD could be determined with the results of PMA activated NBT slide test. This test can be easily performed. It would be better to do this test routinely as one of the tests for the screening of the immmunodeficiency syndrome in childhood.

계단 오르기 동작에서 발 딛기 전략에 따른 발목 부하의 차이

Eui Bum Choi,Hyeong Min Jeon,Jae Hoon Heo,Gwang Moon Eom 대한인간공학회 2018 대한인간공학회 학술대회논문집 Vol.2018 No.5