• 한국도로학회논문집
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• 제11권4호
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• pp.79-85
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• 2009

국내의 줄눈 콘크리트 포장설계에 주로 사용되는 다웰바 설계 기준은 국외 기준과 검증되지 않은 경험에 의해 사용되고 있다. 또한 다웰바의 설치는 길어깨나 하부층의 조건 등을 고려하지 못한 상태에서 슬래브 폭에 대하여 일률적으로 적용되고 있다. 이에 다웰바를 합리적으로 설계하기 위해서는 다웰바 거동에 대한 고찰이 요구되며, 이를 3차원 유한요소해석을 이용하여 수행하였다. 다웰바의 거동에 대한 3차원 유한요소해석 결과의 타당성을 검토하기 위하여 Timoshenko이론의 다웰바 거동을 비교하였다. 또한 실제 도로에서 교통하중이 여러 개의 다웰바에 분산 전달하는 다웰바의 그룹작용(Dowel Group Action)을 3차원 유한요소해석을 통하여 다웰바 그룹작용 적용범위를 산정하였다. 본 연구에서 제시된 다웰바 그룹작용 범위는 Friberg의 그룹작용 범위와는 상이한 결과가 나타났으며, 비교적 최근 연구 결과인 Tabatabaie의 그룹작용 범위의 연구결과와 유사한 결과가 도출되었다.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2011년도 정기총회 및 추계학술대회 논문집
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• pp.375-381
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• 2011

The passage of railway vehicles generates mechanical vibrations and noises. This problem can be mitigated by the 'floating slab track' that isolating from infrastructures by installing vibration isolator in the concrete slab track. In the previous researches, adjacent floating slab tracks are connected by dowel bar system. It has been reported that many dowel bars with less diameter show better load transfer efficiency (LTE) compared to small number of dowel bars with larger diameter under the condition of the same dowel area. In this study, dowel system is further considered as a concrete anchorage system and the design strength of the dowel system was evaluated based on ACI code 318-08 Appendix D. The design strength of dowel system is then verified against failure load test of floating slab system.

• Journal of the Korean Wood Science and Technology
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• 제23권4호
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• pp.91-97
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• 1995

Cyclic tests were performed with dowel joints which are being widely used for furniture manufacturing in Korea. In this study, effects of various factors-such as species of joint members, diameter and length of dowels, and space between dowels-on stiffness, strength and damping ratio of joints were evaluated and concluded as follows: 1. Under cyclic loads, failure of dowel joints were caused by bending failure of dowels. 2. Dowel joints were evaluated to be stiff but general load carrying capacities were relatively low. 3. Joint moduli and damping ratios of dowel joints decreased as diameter and length of dowels, and space between dowels increased. 4. In dowel joints, properties of dowel itself have greater effects on stiffness and strength of joints than properties of joint members.

• Journal of the Korean Wood Science and Technology
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• 제44권5호
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• pp.736-742
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• 2016

나무못은 다양한 구조물의 목재부재들을 연결하는데 일반적으로 사용된다. 하지만 국산재의 나무못 유지력에 대한 자료는 매우 부족하다. 본 연구는 나무못의 직경과 천공여척이 유지력 특성에 미치는 영향에 대해 알아보기 위해 실시했다. 실험 블록은 두께 15 mm인 소나무와 잣나무 목재로 제작했다. 6, 8 및 10 mm 직경인 나무못은 밤나무, 잣나무 및 백합나무 목재로 각각 제작했다. 연구결과 나무못 직경이 증가하면 유지력은 선형으로 증가했지만 유지력 강도는 감소했다. 본 연구는 또한 천공여척이 작아질수록 유지력과 유지력 강도도 선형으로 증가하는 것을 보였다.

• The Journal of Advanced Prosthodontics
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• 제5권1호
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• pp.16-20
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• 2013

PURPOSE. To assess the retention of glass fiber post cemented with self-adhesive resin cement into optimum and over-prepared root canals following obturation in the presence of either eugenol (EB) or calcium hydroxide (CB)-based sealers. MATERIALS AND METHODS. Roots of extracted premolars were endodontically-treated in 5 groups (n = 10). Roots of Group 1 (control) were left with no obturation and then optimally prepared to receive endodontic dowels. Other root canals were obturated with gutta-percha in the presence of either eugenol-based (Groups 2 and 4) or calcium hydroxide-based (Groups 3 and 5) sealer. Dowel spaces were prepared with optimal diameter in Groups 2 and 3, one size larger in Groups 4 and 5. Standardized fiber posts were luted to the prepared spaces using self-adhesive resin cement and its retention was then tested on an universal testing machine. Both one-way ANOVA and Tukey's HSD comparisons (${\alpha}$=0.05) were used to identify the significance of inter-group retention differences. Scanning electron microscopy (SEM) of both optimally and over-prepared dowel spaces was also considered to figure the nature of their interior out. RESULTS. The post retention was significantly higher to the non-obturated, optimally-prepared dowel spaces of Group 1 compared to the obturated, optimally-prepared ones of Groups 2 and 3. For each dowel space diameter, root canals obturated using CB of Groups 3 and 5 showed significantly higher dowel retention compared to those obturated using EB of Groups 2 and 4. Post retention to the over-prepared dowel spaces of Groups 4 and 5 was significantly higher than that recorded for the optimally-prepared ones of Groups 1-3. SEM images revealed traces of endodontic sealer and gutta-percha on the walls of the optimally-prepared dowel spaces. CONCLUSION. Despite the adverse effect of endodontic sealers on the retention of fiber posts, the over-preparation of dowel spaces helps to improve the retention.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2010년도 춘계학술대회 논문집
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• pp.1287-1292
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• 2010

Recently, many railway stations are built under the railway line in urban area. The passage of railway vehicles generates mechanical vibrations of a wide range of frequency. Thus, it is required to place structural vibration isolation systems to reduce vibration and noise originating from surrounding environments. This study utilizes elastometric bearings as a vibration isolation system. The slab track system on elastometric bearings is called "low vibration track" or "floating slab track." In this low vibration track system, dowel bars or plates can be installed to minimize the discontinuity of displacement between adjacent floating slab tracks. This study is to numerically investigate the effects of dowel members on static behavior of the low vibration track. The study involves two steel dowel systems including dowel bars and dowel plates. Each dowel system is analyzed under the service load condition to assess load transfer efficiency (LTE).

• 대한토목학회논문집
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• 제33권5호
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• pp.2125-2133
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• 2013

최근 콘크리트궤도 공법이 증가함에 따라 인접한 슬래브를 연결하는 방법에 대한 관심이 높아지고 있다. 슬래브의 연결부는 효과적인 하중전달, 변형 연속화, 응력 분산을 위해서 다웰 시스템이 다수 적용된다. 본 연구에서는 콘크리트 슬래브 다웰연결부를 효율적으로 이상화할 수 있는 연결부의 집중 전단스프링 (Lumped shear spring) 모델을 제안한다. 전단 스프링 모델의 강성은 다웰바의 강성과 유격을 고려하였으며, 강도는 연결부의 전단파괴에 근거한 Concrete Capacity Design(CCD) 방법에 의해 산정되었다. 해석모델의 타당성을 검증하기 위하여 다웰로 연결된 슬래브 실험체를 제작하고 재하실험을 수행하였다. 제안된 해석모델은 다웰과 콘크리트 간의 유격으로 인한 초기 비선형성 및 콘크리트 재료 비선형성을 합리적으로 반영하고 있는 것으로 분석되었다. 따라서 향후 슬래브 다웰 조인트로 연결된 콘크리트궤도의 파괴 시까지의 비선형 거동을 합리적으로 예측함으로써 철도 궤도의 설계 시 효과적으로 활용될 수 있을 것이다.

• KCI Concrete Journal
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• 제12권2호
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• pp.23-30
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• 2000

This paper presents behavior of concrete pavement at transverse joint subject to static test load. The test was conducted on 1/10 scale model in the laboratory. Load transfer across the crack is developed either by the interlocking action of the aggregate particles at the faces of the joint or by a combination of aggregate interlock and mechanical devices such as dowel bars. In this study, significant three variables considered to the performance of joints were selected. : (a)diameter of dowel bars(2.5mm, 3.0mm, 4.0mm), (b)presence or absence of dowel bars, (c)aggregate types(crushed stone, round stone). Experimental results were analyzed to find relationships among displacement of discontinuous plane at jointed slab, load transfer efficiency and joint opening, etc. Displacement of discontinuous plane at joint was decreased according to the increase of dowel bar diameter. In addition, it is found that model slabs made using crushed stone had better load transfer characteristics by aggregate interlock than model slabs made using similarly graded round stone. Displacement of discontinuous plane was increased according to the increase of loading. In addition, it was decreased as dowel diameter(2.5mm, 3.0mm, 4.0mm) was increased. In the case of slab without dowel bars, displacement of discontinuous plane was greatly increased and load transfer effciency of slab applied crushed stone was shown 30 percent greater than round stone. In addition, load transfer efficiency of slabs, which were made using crushed and round stone without dowel bars, was decreased to 20 percent and 30 percent, respectively as it was compared with slabs made us-ing dowel bars.

• 한국도로학회논문집
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• 제16권3호
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• pp.9-20
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• 2014

PURPOSES : This study is to compare load transfer efficiency of key joint and dowel joint for airport concrete pavement. METHODS : As AC150/5320-6D of FAA's [Advisory Circular] was changed into AC150/5320-6E, Key joint type of rigid pavement were excluded from Construction Joints. LTE(Load Transfer Efficiency) of dowel joint and key joint were compared by times and seasons through pavement temperature measurement, ocular investigation and HWD measurement. RESULTS : For the joint performance grade of No. 2(The second) runway of airport, 12% of poor rate was observed in key joint and 2% of poor rate in dowel joint. Poor rate of key joint was increased to 17%, if only No. 3~No. 6 slabs, which are mostly loaded from the airplanes, were applied for the study. In apron area, LTE poor rate of key joint was high in winter, and LTE poor rate of dowel joint was at least above 'Fair' grade. In summer, 'Fair' for key joint, 'Acceptable' for dowel joint appeared. CONCLUSIONS : As results, dowel joint was superior than key joint for LTE. Deviations of seasons and times were smaller in dowel joint's result. And LTE in winter was lower than LTE in summer.

• Journal of the Korean Wood Science and Technology
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• 제23권3호
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• pp.40-47
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• 1995

This study was carried out to develop a finite element analysis model that considers the semi-rigid characteristics of a wood-dowel joint, which is different from conventional joints that are used in the field of engineering. Wood-dowel joints are classified as semi-rigid joints that possess the following characteristics: (1) they are less stiffer than rigid joints and (2) their stiffness is determined by the dowel's diameter, depth of dowel embedment in the face member and quantity of pin dowels. In this study a finite element model that considers the changes in stiffness according to the above mentioned factors was developed and its suitability was verified by experiments using a wood-dowel joint test specimen made up of particleboards. After comparing the experimental results and the analysis results of the wood-dowel joint which was applied with the proposed finite element model, less than 10% of error was found which is considered to be negligibly small. Hence this shows that this proposed finite element model can be used to predict deformation of wood-dowel joints.