Earticle

The object of this study is theoretically and experimentally investigated to flexural behaviors of form deckplate slabs using wire mesh. The wire mesh instead of deformed bars is used to improve convenience of construction. Simplifying the stage of processing and assembling reinforcing bars, the efficiency in reinforced concrete construction are increased. Total 12 specimens were tested with oil-jack system of 1,000kN capacity. Test variables are concrete slab height(150mm, 175mm), types of main bars(1-D6, 2-D6, 3-D6) in compression and tension regions, and width in bottom face of deckplate(600mm, 690mm). The vertical loading by monotonic is applied to investigate the yielding strength, maximum strength, initial stiffness and failure modes. Test results are as follows ; (1) The concrete slab using wire mesh has excellent constructionability because the interval of the wire mesh will be able to regulate freely with option. (2) Higher stiffness and strength was shown that more the wire mesh was, the thicker the slab was. (3) The maximum strength of slab using wire mesh instead of reinforced bars is 1.05 1.72 times than those of calculated results.

본 연구의 목적은 부하방식(CRT, VRT)에 따른 백 스쿼트 시 휴식 시간 진행 후 수직점프 수행에 미치는 급성 효과 를 비교 분석하는 것이다. 연구대상은 19세 이상의 성인 14명이 실험에 참가하였고, 사전 수직점프에 대한 높이와 근전도 자료를 수집하였고, 1RM의 60%의 부하로 각 부하방식(고정저항, 가변저항)에 따라 백 스쿼트 실시한 후 수직점프의 높 이와 하지 근활성도를 산출하여 휴식시간 사이에 대한 차이를 반복측정 이원변량분석을 통하여 검증하였다. 본 연구 결과 로 첫째, 부하방식에 따른 백 스쿼트 시 수직점프의 높이는 가변저항 적용 시 높았다. 둘째, 근활성도에서 외측광근은 하강구간에서 가변저항 적용 시 낮은 근활성도를 보였고, p2도 가변저항 적용 시 낮은 근활성도를 보였다. 셋째, 대퇴이두 근은 하강구간에서 가변저항 적용 시 낮은 근활성도를 보였다. 넷째, 전경골근은 상승구간에서 가변저항 적용 시 낮은 근활성도를 보였다. 다섯째, 비복근은 하강구간에서 가변저항 적용 시 높은 근활성도를 보였다.

The purpose of this study was to compare and analyze the acute effects of rest periods on vertical jump performance during back squats using different loading methods (CRT and VRT). 14 adult participants aged 19 years or older participated in the experiment. Pre-test data on vertical jump height and EMG were collected. After performing back squats with a load of 60% of 1RM for each loading method (constant resistance, variable resistance) at 60% of 1RM. Vertical jump height and lower limb muscle activity were then measured, and differences between rest periods were verified using repeated measures analysis of variance. As a result of this study, first, vertical jump height during back squats was significantly higher under the VRT condition. Second, the vastus lateralis showed lower activity at p1 and p2 when VRT was applied. Third, the biceps femoris exhibited lower activity at p1 with VRT. Fourth, the tibialis anterior exhibited low muscle activity at p2. Finally, the gastrocnemius exhibited high muscle activity at p1 with VRT.

In piping systems, trapeze hangers are subjected to vertical and horizontal seismic loads and stiffeners are used. In this study, monotonic compression tests were conducted with the removable stiffeners using three variables: stiffener clamp fixing position, section length, and installation direction. The maximum load reinforced with stiffeners could withstand a compressive load of 11kN by applying a safety factor of 10%. It could be estimated that the fixing clamp spacing or the length of shape and load had a proportional relationship. And the stiffener must be fixed in the direction of the strong axis on hinge parts. Also the stiffener buckiling load design proposes to use a method of calculate the flexural buckling compressive strength of and unreinforced full threaded bolt.

This paper presents the feature profile evolution silicon deep trench etching, which is very crucial for the commercial wafer process application. The silicon deep trenches were etched with the SF6 gas & Hbr gas based process recipe. The optimized silicon deep trench process resulted in vertical profiles (87o~90o) with loading effect of < 1%. The process recipes were developed for the silicon deep trench etching applications. This scheme provides vertically profiles without notching of top corner was observed. In this study, the production of SF6 gas based silicon deep trench etch process much more strongly than expected on the basis of Hbr gas trench process that have been investigated by scanning electron microscope (SEM). Based on the test results, it is concluded that the silicon deep trench etching shows the sufficient profile for practical MOS FET silicon deep trench technology process.

수직구와 수평 터널 주위 지층 변화, 지진파 방향성이 접속부의 동적 거동 특성에 미치는 영향을 연구하였다. 유한 요소 기반의 MIDAS GTS NX 프로그램을 이용한 3차원 시간이력 해석을 통해 검토하였다. 연구결과 연약지반에서 장주기의 지진파가 수평 터널 방향으로 발생하였을 때 접속부 상부에서 최대 변위가 발생하는 것으로 나타났다. 또한 수직구와 수평 터널의 서로 다른 거동 및 지층 경계면의 영향으로 인해 응력집중 현상이 발생하여 문제가 될 수 있음을 확인 할 수 있었다. 연구 결과는 수직구와 수평 터널의 접속부 구조물 내진설계를 위한 기초자료로 활용 될 수 있을 것으로 기대된다.

3D time history analysis was performed on vertical shaft-tunnel connection to provide insight into the dynamic stress-strain behavior of the connection considering the effects of soil layers, periodic characteristics and wave direction of earthquakes. MIDAS GTS NX based on FEM (Finite Element Method) was used for this study. From this study, it is revealed that the maximum displacement occurred at the upper part of the connection when the long period seismic waves propagate through the tunnel direction in soft ground. Also, stress concentration occurs due to different behaviors of vertical shaft and tunnel, and the stress concentration could be influence for safety on the connection. The results of this study could be useful for the seismic performance design of vertical shaft-tunnel connection.

교량의 슬래브에 파손이 발생할 경우 슬래브의 보수보강을 위한 공사로 인해 차량 통행이 제한된다. 모듈러 교량의 경우 이러한 시간적 비용을 줄일 수 있는 방법으로서 많은 연구가 진행되고 있다. 본 연구에서는 연결부에 높은 응력이 발생하는 모듈러 도로 슬래브를 온도하중과 차량하중을 적용하여 구조해석을 실시하였으며 수직연결부 부근에 나선철근을 매입하여 그 성능을 확인하였다. 또한 인양 시의 모듈러 도로 슬래브의 거동 및 취약부분을 확인하기 위하여 인양하중을 적용한 구조해석을 실시하여 유리한 조건의 인양방법을 살펴보았다. 그 결과 온도하중에 의해 수직연결부가 항복하는 것이 확인되었으며, 나선철근을 수직연결부 부분에 매립할 경우 인양 시에 구조물의 손상이 감소하는 것을 확인할 수 있었다. 또한 6개 수직연결부를 이용하여 인양할 시 3개 수직연결부 사용대비 50%의 응력을 감소시킬 수 있는 것으로 확인되었다.

In terms of bridge construction, the concrete deck slab is weak members compared to beam members of the bridge supports. Deck slabs must be sound to support and distribute vehicle loads. If slabs are not enough to support the loads, it should be replaced. Bridge deck replacement has been an important industry over the world since the construction is simplified to shorten construction time and to save construction costs. Slab module provides a quickly, easily and reliably construction method in order to avoid high cost and minimum traffic disruption. in addition, slab module shows high reliability since they are factory products. However, slab module should be considered in the performance under various loads. In this study, structural analysis is performed to evaluate the performance of slab module under vehicle loads and temperature loads. Spiral rebar is also utilized around the vertical joints to improve the structural integrity under the lifting loads. In order to confirm the weak area of slab module for the lift condition, numerical analysis has been performed.

Model soil tank tests were conducted in sandy soil to investigate the effect of surcharge strip loads on vertical stress distribution in soil. A total number of 6 tests were performed using one loading plate and two relative density(55%, 65%). The soil was considered as an elastic material, while no friction was allowed between the wall and the soil. Measured stress values were compared to predictions defined by Frohlich, Boussinesq and Westergaard. The comparison of measured values and predictions used the ratio between the soil pressure and load value. Results of this study demonstrated that experimental values were generally larger than predictions. The Frohlich analysis provided the best prediction, while the Boussinesq analysis and Westergaard theory not presented a satisfactional result.