• Journal of the Korea Concrete Institute
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• v.28 no.1
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• pp.3-11
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• 2016

The concern about hollow core PC slab has been increased to improve the workability during a construction of building by reducing self weight of structural members. In this manner, recently, TRS (Tripple Ribs Slab) was developed as a new type of half PC slab system. TRS member consists of the triple webs and the bottom flange prestressed by strands. The slab system is completed by casting of topping concrete on the TRS after filling styrofoam between the webs. This paper, presents a flexural experiment to investigate the flexural capacity of the TRS. Five full scale TRS members were made and tested under simple support condition to be failed by flexure and their strength was evaluated by code equations; the variables in the test are the depth and the presence of topping or raised spot formed when slip-forming. In addition, a nonlinear sectional analysis was performed for the specimens and the result was compared with the test results. From the study, it was found that the TRS has enough flexural strength and ductility to resist the design loads and its strength can be suitably predicted by using code equations. The raised spot did not affect the strength so that the spot need not to be removed by doing additional work. For the more accurate prediction of TRS's flexural behavior by using nonlinear sectional analysis, it is recommended to consider the concrete's brittle property due to slip-forming process in the modeling.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.6
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• pp.3736-3741
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• 2015

Crash impact test is conducted to verify the crashworthiness of fuel tank. Success of the crash impact test means the improvement of survivability of crews by preventing post-crash fire. But, there is a big risk of failure due to huge external load in the crash impact test. The failure of crash impact test can result in serious delay of a entire rotorcraft development because of the design complement and re-production of the test specimens requiring a long-term preparation. Thus, the numerical simulations of the crash impact test has been required at the early design stage to minimize the possibility of trial-and-error in the real test. Present study conducts on the numerical simulation of phase I crash impact test using SPH supported by crash simulation software, LS-DYNA. Test condition of MIL-DTL-27422 is reflected on analysis and material data is acquired by specimen test of fuel cell material. As a result, the crash load on the skin material, overlap area and metal fitting is estimated to confirm the possibility of acquisition of the design load for the determination of the overlap area and adhesive strength.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.25 no.1
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• pp.51-56
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• 2012

Crashworthy fuel cells have been widely implemented to rotorcraft and rendered a great contribution for improving the survivability of crews and passengers. Since the embryonic stage of military rotorcraft history began, the US army has developed and practised a detailed military specification documenting the unique crashworthiness requirements for rotorcraft fuel cells to prevent most fatality due to post-crash fire. Foreign manufacturers have followed their long term experience to develop their fuel cells, and have reflected the results of crash impact tests on the trial-and-error based design and manufacturing procedures. Since the crash impact test itself takes a long-term preparation efforts together with costly fuel cell specimens, a series of numerical simulations of the crash impact test with digital mock-ups is necessary even at the early design stage to minimize the possibility of trial-and-error with full-scale fuel cells. In the present study a number of numerical simulations on fuel cell crash impact tests are performed with a crash simulation software, Autodyn. The resulting equivalent stresses are further analysed to evaluate a number of appropriate design parameters and the artificial neural network and simulated annealing method are simultaneously implemented to optimize the crashworthy performance of fuel cells.

• Journal of Energy Engineering
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• v.15 no.3 s.47
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• pp.202-208
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• 2006

Although the importance of good conservation of historic sites including ancient royal tombs is well aware, still not much attention has been paid for the facilities and systems to preserve those historic sites, which includes precious artifacts as wall paints and carved works, etc. Even the general understanding about the environment of the underground space or tombs is not satisfactory. In the present study, vibration levels due to the operation of an HVAC system to maintain the desired indoor temperature and humidity are investigated experimentally. According to the measured data, the level of vibration inside the present model tomb with the indoor unit inside, showed order of magnitude less values than the Swiss Standards, but still higher than the value suggested by German standards, which is, zero. Further study will be pursued for cases including different ways of installation, because the vibration level depends not only on the system design, but also on the installation methods.

• Journal of the Korea Concrete Institute
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• v.15 no.4
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• pp.615-622
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• 2003

The purpose of this study is to propose the more reasonable equation of bond strength of grout-filled splice sleeve. To accomplish this objective, total 60 full-sized specimens were tested under monotonic loading. The experimental variables are compressive strength of mortar, embedment length and size of reinforcing bars. Following conclusions are obtained; 1) If the adequacy of existing equations which estimate the bond strength of grout-filled splice sleeve are investigated, they underestimate the bond strength of grout-filled splice sleeve by 8-18%. Also the existing equations have a tendency to underestimate with decrease in the embedment length of reinforcing bars. 2) From the test result of bond failure, the equation which estimates the confining pressure of grout-filled splice sleeve was proposed by making multiple regression analyses of which independent variables are embedment length of reinforcing bars and compressive strength of mortar. This equation predicted the measured bond capacity of this test more accurately than existing equations and eliminated the deviation according to the embedment length of reinforcing bars.

• Journal of Korean Society of Steel Construction
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• v.28 no.1
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• pp.53-64
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• 2016

The double split tee connection, a type of beam-to-column moment connection, exhibits different behavioral characteristics according to changes in the thickness of the T-stub flange, the gauge distance of the high-strength bolt, and the number and diameter of high-strength bolts. In general, the double split tee connection is idealized and designed so that a T-stub fastened to the top and bottom supports a flexural moment, and a shear tab supports a shear force. However, if the double split tee connection is applied to low-and medium-rise steel structures, the size of the beam member becomes small, and thus the shear tab cannot be bolted to the web of a beam. In this regard, this study was conducted to propose connection details to ensure that the double split tee connection with a geometric shape can display sufficient shear resisting capacity. To this end, experiments were conducted using full-scale specimens for the double split tee connection.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.41 no.10
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• pp.1005-1009
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• 2017

In this study, the shock resistance of a gas turbine package subjected to a shock load caused by non-contact underwater explosion was investigated using numerical analysis. To perform shock analysis, the time-history shock load was calculated according to BV-043 (German Navy Regulation). The direct transient response analysis in the time domain for the simplified Whole Engine Model (WEM) was performed using the calculated shock load. In addition, the structural integrity of a detailed model was evaluated by considering the shock load transferred to each component. As a result, it was confirmed that the safety factor was at least 1.0 as compared with the reference stress. Finally, the structural and functional integrity of the Engine Management System (EMS) of the gas turbine package was verified through an actual shock test.

• Proceedings of the Korea Water Resources Association Conference
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• 2011.05a
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• pp.86-86
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• 2011

1922년 R. L. Parshall이 고안한 파샬플륨은 현재 사용되고 있는 개수로 유량계로서는 가장 많은 실험자료를 보유하고 있다. 위어에 비해 설치가 어렵고 경제성이 떨어지는 단점도 있지만 설치 후에는 상대적으로 다른 시설보다 토사이동이 원활하다는 장점이 있어 하수 및 폐수 등의 유량측정에 많이 적용되고 있다. 용담저수지의 주요 지천인 금강본류와 구량천 2곳에는 국가가 관리하는 수위관측소가 있다. 설치지점의 지명을 따 동향수위관측소와 천천수위관측소로 운용되고 있으며, 동향수위관측소 약 170 m 하류와 천천수위관측소 약 2.5 km 상류 2곳에 갈수기 유량조사를 위한 파샬플륨이 설치되었다. 동향파샬프륨과 천천파샬플륨은 갈수기 유량을 고려하여 Iso 9826의 파샬플륨 번호 10(Parshall flume No. 10)과 유사한 규격(설치당시 목부(Throat)폭 5ft))으로 설계되었으며, 플륨으로 흐름을 유도하는 유입부(Entrance section) 좌 우 횡단방향에 보를 연결하여 상대적으로 하폭이 넓은 자연하천에 적용하였다. 수년간의 현장운용 결과, 파샬플륨의 가장 큰 장점이었던 원활한 토사이동이 보로 인해 차단되고, 누적된 토사가 흐름을 왜곡시킴으로서 플륨내 수위로부터 환산한 유량값에 비교적 큰 오차를 발생시 킬 수 있음을 알게 되었다. 본 연구는 이러한 문제의 원인이 상류에 누적된 토사에 있음을 규명하고 대처방안을 제시하기위해 동향파샬플륨을 대상으로 수행되었다. 플륨을 통한 유량자료의 신뢰도는 (1) 플륨내 정밀유량측정, (2) 50 m 하류에서의 도섭법에 의한 유량측정 그리고 (3) 130 m 하류에서의 도섭법에 의한 유량측정을 통하여 비교 및 검증하였다. 조사결과 플륨내 수위는 상류에 퇴적된 토사로 인해 일정하지 않으며 이로 인해 유량에 오차가 발생하고 있음이 확인되었다. 또한 본 연구에서는 자연하천에서의 파샬플륨 적용을 위해 토사이동을 고려한 설비의 구조개량을 병행하였다. 새로운 형태의 파샬플륨은 '에코플륨'이라 명명하였으며 원활한 토사이동과 인공구조물에 의한 자연경관 훼손을 방지할 수 있는 두 가지의 효과가 기대된다. 현재 실물모형의 제작이 완료되어 실내실험을 수행하고 있으며, 머지않은 장래에 현장설치가 가능하다고 판단된다.

• Journal of the Korea institute for structural maintenance and inspection
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• v.20 no.3
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• pp.33-41
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• 2016

Concrete is inherently a good fire-resistance material among all other constrcution materials and protects the reinforcing steel inside. This study investigates the material characteristics of concrete and steel bar inside the full scale reinforced concrete(RC) beam exposed to fire test. The fire test specimen was 4 m long and the test was conducted under no loading condition following KS F 2257. Fire source is simulated by ISO 834 and number of thermocouples were installed to measure temperature variation of surfaces and inside of the beam. The measured compressive strength of cored specimen, which was exposed to fire test, was 11 MPa, about 66% lower than the strength before exposure. The yielding strength of steel bar also decreased about 75 MPa, about 17% lower. The measured temperature of protected steel bar was around $649^{\circ}C$, the critical limit, after 4 hour exposure.

• Land and Housing Review
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• v.1 no.1
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• pp.67-73
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• 2010

Method of protruding steel bar embedded in PHC pile for connecting with foundation plate is an intermediate form of fixed and hinged connection and has often been used in architectural structures such as apartment complex. However, mechanical properties of this method have not been proved and its construction process is not simple. In this study, therefore, by analyzing previous research and by considering ratio of steel bar and concrete in PHC pile, which is minimum reinforcement of rebar, the newly optimized method of reinforcing joint of PHC pile and foundation plate is suggested with respect to PHC pile type (PHC 450, PHC 500, and PHC 600). To assess mechanical properties (ultimate tensile and shear strength) of joint of PHC pile and foundation plate, full scale experimental tests are performed. As a result, all cases are satisfied with required design criteria and can be practically applied. Our results indicate that reduction of rebar reinforcement compared to previous method would lead cost saving in PHC pile construction.