• Proceedings of the Korean Society of Disaster Information Conference
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• 2017.11a
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• pp.197-198
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• 2017

인공재해와 자연재해로 인해 발생하는 비정상 하중에 의해 국부손상이 발생된 철골 교량 구조물은 추가적인 2차 붕괴의 위험요소들을 내재하고 있어 신속한 전면 해체가 요구된다. 본 시공 사례는 건설실패와 태풍 및 지진으로 국부손상이 발생된 철골 트러스 구조의 교량의 긴급해체를 위해 발파해체 공법을 적용한 사례이다. 철골 부재의 절단을 위해 성형폭약이 필요하지만 현지에서 수급이 불가능한 상태이기 때문에 장약용기를 직접 제작하고 에멀젼 폭약을 충전하여 만든 성형폭약을 이용하여 발파해체에 적용하였다. 직접 제작한 성형폭약을 이용하여 발파해체한 결과 철골 부재가 정확히 절단되면서 교량의 중앙부가 수직자유낙하하고, 교량의 양 끝단은 지지부를 중심으로 회전낙하 하였다. 또한 존치 구조물 및 주변에 피해가 발생하지 않았으며, 발파 후 파쇄 상태는 매우 양호하였다. 이로 인해 직접 제작한 성형폭약의 절단 성능을 확인할 수 있었으며, 신속하고 안전하게 국부손상이 발생된 구조물을 해체하였다.

• Proceedings of the Korean Nuclear Society Conference
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• 1997.05b
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• pp.256-261
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• 1997

국내 원전의 사용후핵연료를 경제적으로 수송할 수 있는 대형 수송용기의 국내개발을 위하여 10년의 냉각기간을 갖는 28다발의 PWR 사용후핵연료를 수송할 수 있도록 기본 설계기준을 설정하였다. 이 대형 수송용기에 대하여 개념설계로부터 결정된 차폐두께와 칫수를 기준으로 기본구조를 결정하고 정상수송조건 및 가상사고 조건에 대한 구조해석을 수행하였다. 대형 수송용기는 내부에 많은 양의 PWR 사용후핵연료를 담고 있으므로 이들 핵연료의 중량은 구조설계에 큰 영향을 미치게 된다. 본 연구의 목적은 28다발의 PWR 핵연료를 담은 대형 수송용기가 9m 높이에서 자유낙하하여 충돌사고를 일으켰을 때의 안전성을 파악하기 위한 것이다. 수송용기가 충돌시 충격면에 발생하는 충격력으로 인한 충격완충체의 변형과 충격흡수, 수송용기에 발생하는 응력, 가속도, 충돌력 등의 동적거동을 파악하여 안전성을 입증하였다.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.10 no.2
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• pp.105-115
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• 2012

Necessity of demonstration test to evaluate the structural integrity of a basket for accident conditions arose during license approval procedure for the WSPP's dry storage facility named MACSTOR/KN-400. A drop test facility for demonstration was constructed in KAERI site and demonstration tests for basket drop were conducted. As the upper welding region of a loaded basket was collided with a dropped basket during the drop test, the welding in this region was fractured and leakage happened after the drop test. The enhancement of basket design was needed since the existing basket design was not able to satisfy the performance requirement. The directions for design modification were determined and six enhanced designs were derived based on these directions. Structural analyses and specimen tests for each enhanced design were conducted. By evaluating structural analysis results and test results, one among six enhanced designs was decided as a final design for revision. The final design was the one to reduce the height of central post of a basket and to decrease the impact velocity with a dropped basket. Test basket models were fabricated with accordance with the final enhanced design. Additional demonstration test was performed for this test model and all the performance requirements were satisfied.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2004.06a
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• pp.436-436
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• 2004

사용후 연료 건식 저장 용기가 낙하, 토네이도, 미사일, 홍수 및 지진으로 인한 사고에 대하여 전복이 발생되었을 때 강체 평면과 충돌에 의한 충돌 하중시의 구조 응력 평가하였다. 이를 위해 저장 용기의 무게 중심이 한계를 넘었을 때의 초기 전복 시작각을 무게 중심을 계산을 통해 구하였다. 상용 코드를 사용하여 전복 응력 해석 수행시 저장 용기의 강체 운동에 의하여 계산 시간이 길어지는 데, 이런 계산 시간을 줄이기 위해 일차 충돌 직전까지의 모델의 속도와 각속도 계산식을 이론적인 방법으로 구하여 해석 초기 조건으로 사용하는 방법에 대하여 제안하였다.(중략)

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.4 no.2
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• pp.139-152
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• 2006

A spent fuel storage cask is required to prove the safety of a canister under a hypothetical accidental drop condition. A hypothetical accidental drop condition means that a canister is assumed to be a lee drop on to a pad of the storage cask during loading it into a storage cask. A pad of the storage cask absorbs shock to maintain the structural integrities of a canister under a hypothetical accidental drop condition. In this paper a finite element analysis for various pad structures was carried out to improve the structural integrity of a canister under a hypothetical accidental drop condition. A pad of a storage cask was designed a steel structure with concrete. The 1/4 height of a pad was modified with a structure composed of a steel and a polyurethane foam as a impact limiter. The effect of a shape of a steel structure was studied. The effects of the thickness of a steel structure and the density of a polyurethane foam was also studied.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.5 no.3
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• pp.199-212
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• 2007

If a type IP-2 transport package were to be subjected to a free drop test and a penetration test under the normal conditions of transport, it should prevent a loss or dispersal of the radioactive contents and a more than 20% increase in the maximum radiation level at any external surface of the package. In this paper, we suggested the analytic method to evaluate the structural safety of a type IP-2 transport package using a thick steel plate for a structure part and a bolt for tying a bolt. Using an analysis a loss or dispersal of the radioactive contents and a loss of shielding integrity were confirmed for two kinds of type IP-2 transport packages to transport radioactive waste drums from a waste facility to a temporary storage site in a nuclear power plant. Under the free drop condition the maximum average stress at the bolts and the maximum opening displacement of a lid were compared with the tensile stress of a bolt and the steps in a lid, which were made to avoid a streaming radiation in the shielding path, to evaluate a loss or dispersal of radioactive waste contents. Also a loss of shielding integrity was evaluated using the maximum decrease in a shielding thickness. To verify the impact dynamic analysis for free drop test condition and evaluate experimentally the safety of two kinds of type IP-2 transport packages, free drop tests were conducted with various drop directions. For the tests we examined the failure of bolts and the deformation of flange to evaluate a loss or dispersal of radioactive material and measured the shielding thickness using a ultrasonic thickness gauge to assess a loss of shielding integrity. The strains and accelerations acquired from tests were compared with those by analyses to verify the impact dynamic analysis. The analytic results were larger than the those of test so that the analysis showed the conservative results. Finally, we evaluated the safety of the type IP-2 transport package under the stacking test condition using a finite element analysis. Under the stacking test condition, the maximum Tresca stress of the shielding material was 1/3 of the yielding stress. Two kinds of a type IP-2 transport package were safe for the free drop test condition and the stacking test condition.

• Journal of the Korean GEO-environmental Society
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• v.15 no.12
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• pp.53-59
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• 2014

In order to obtain basic data for reasonable design of rockfall prevention net unreasonably being designed according to experiences, this paper determined a standard cross section and analyzed the effects of parameters such as inclination and height of slope faces, rockfall weight, separation distance on rockfall behaviors such as bounce height, kinetic energy and passage rate. The weight of rockfall changed from 400 kg to 700 kg and then to 1,000 kg. With the height of 20 m as the standard, the test was conducted with the inclination at $63^{\circ}$ and $55^{\circ}$ which may affect rockfall behaviors. Analysis was made while changing the fall height of rockfall from 3 m to 15 m and then to 20 m, thereby analyzing and evaluating changes in maximal kinetic energy occurring in the base of slope. According to the analysis result, in designing a rockfall prevention wire net, a design considering various conditions including inclination of the slope, expected size or weight of rockfall, situation of the slope and the shape of rockfall, and rockfall trace is judged necessary beyond the current uniform application.

• Explosives and Blasting
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• v.36 no.1
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• pp.20-33
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• 2018

A locally damaged structure is a structure that cannot be reused due to having parts that have lost their structural function as a result of abnormal load across the interior or exterior of the structure. The causes of the abnormal load occurrences can be classified into natural disaster and artificial disaster. Locally damaged structures caused by this abnormal load have risk factors that may lead to the possibility of additional secondary collapses, so such structures require immediate and complete dismantling. The case presented in this study involves the application of explosive demolition to a steel truss structured bridge in the Philippines that was damaged due to construction failures and the hurricane. Although shaped charges were needed in explosive demolitions, difficulties in locally obtaining such material. So, we made a charge container to charging of emulsion explosive during the explosive demolition. The explosive demolition resulted in the vertical free fall of the mid-section of the bridge and the free fall rotating of the both end section of the bridge. The neighboring posts and bridge piers did not show signs of damages, while post-demolition fragmentation of removed parts was found to be satisfactory.

• Journal of Radiation Protection and Research
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• v.26 no.1
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• pp.35-43
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• 2001

All of sealing capsules to transport a special form radioactive material should be designed and fabricated in accordance with the design criteria prescribed in IAEA standards and domestic regulations. The objective of this study is to demonstrate the safety of a shipping capsule for $^{192}Ir$ special form radioisotope which produced in the HANARO. The safety tests were carried out for the impact, percussion, bending and heat test conditions. And leakage tests were carried out before and after the each test. Also, the safety analyses wert performed using computer codes in order to verify the test results. The capsule showed slight scratches and deformation, and maintained its structural and thermal integrities in all tests without any severe damage or melting. It also met the allowable limits of leakage rate after each test. Therefore, it has been verified that the capsule was designed and fabricated to meet all requirements for the special form.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.37 no.3
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• pp.232-239
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• 2009

The prediction of the separation trajectories of external stores carried by military aircraft is an important task in the area of aircraft design having the objective to define the operational, release envelopes. This paper presents the results obtained for safe store separation from a fighter aircraft by experimental methods in the subsonic wind tunnel. The problems associated with separation of external stores can be studied by the use of several wind-tunnel test techniques. Attention is given the two most useful techniques: 1) dynamically scaled drop-model testing, 2) grid testing. A description of each method is given and data obtained are shown to validate the similarity within acceptable limits.