• Nuclear Engineering and Technology
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• v.47 no.3
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• pp.240-252
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• 2015

In the original licensing application for the prototype fast-breeder reactor, MONJU, the event progression during an unprotected loss of flow (ULOF), which is one of the technically inconceivable events postulated beyond design basis, was evaluated. Through this evaluation, it was confirmed that radiological consequences could be suitably limited even if mechanical energy was released. Following the Fukushima-Daiichi accident, a new nuclear safety regulation has become effective in Japan. The conformity of MONJU to this new regulation should hence be investigated. The objectives of the present study are to conduct a preliminary evaluation of ULOF for MONJU, reflecting the knowledge obtained after the original licensing application through CABRI experiments and EAGLE projects, and to gain the prospect of in-vessel retention for the conformity of MONJU to the new regulation. The preliminary evaluation in the present study showed that no significant mechanical energy release would take place, and that thermal failure of the reactor vessel could be avoided by the stable cooling of disrupted-core materials. This result suggests that the prospect of in-vessel retention against ULOF, which lies within the bounds of the original licensing evaluation and conforms to the new nuclear safety regulation, will be gained.

• Nuclear Engineering and Technology
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• v.56 no.7
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• pp.2474-2479
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• 2024

In-Vessel Retention (IVR) is a key technology to retain the molten core in the reactor vessel during severe accidents of Pressurized-water reactors (PWRs). In order to gain the safety margin of IVR, it is crucial to enhance the critical heat flux (CHF) of the reactor vessel, which is submerged in a water pool. To enhance the CHF, we have designed and additive-manufactured porous grid plates with a 3-D printer for design flexibility. We measured the CHF for the porous grid plate on the boiling heat transfer surface and found that the CHF was enhanced by 50 % more than that of the bare surface. The CHF enhanced more with a narrower grid pitch and a lower grid height. The visual observation study revealed that the vapor film was formed at the bottom of the grid plate.

• Journal of Hydrogen and New Energy
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• v.22 no.3
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• pp.363-371
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• 2011

In this paper, a three-dimensional hydrogen desorption model is developed to precisely study the hydrogen desorption kinetics and resultant heat and mass transport phenomena in metal hydride hydrogen storage vessels. The metal hydride hydrogen desorption model, i.e. governed by the conservation of mass, momentum, and thermal energy is first experimentally validated against the temperature evolution data measured on a cylindrical $LaNi_5$ metal hydride vessel. The equilibrium pressure used for hydrogen desorption simulations is derived as a function of H/M atomic ratio and temperature based on the experimental data in the literature. The numerical simulation results agree well with experimental data and the 3D desorption model successfully captures key experimental trends during hydrogen desorption process. Both the simulation and experiment display an initial sharp decrease in the temperature mainly caused by relatively slow heat supply rate from the vessel external wall. On the other hand, the effect of heat supply becomes influential at the latter stages, leading to smooth increase in the vessel temperature in both simulation and experiment. This numerical study provides the fundamental understanding of detailed heat and mass transfer phenomena during hydrogen desorption process and further indicates that efficient design of storage vessel and heating system is critical to achieve fast hydrogen discharging performance.

• Proceedings of the Korean Information Science Society Conference
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• 2004.04a
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• pp.913-915
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• 2004

시술 중 제공되는 2D영상은 실시간으로 환자와 시술도구의 상태정보를 제공해주지만 환부의 입체적ㆍ해부학적 파악이 어렵다. 따라서 긴 촬영시간으로 시술 전 획득되는 3D영상과 시술 중 얻어지는 2D영상간 정합영상은 영상 유도술에 있어서 유용한 정보를 제공한다. 이를 위해 본 논문에서는 볼륨영상으로부터 혈관모델을 추출하고 이를 평면으로 투영하였다. 두 2D영상에서 정차대상이 되는 혈관골격을 추출한 후 혈관의 분기특성을 고려 한 초기정합을 수행하였다. 크기와 초기 위치를 맞춘 혈관골격을 골격간 거리가 최소가 되도록 반복적으로 혈관을 기하변환시키고 최종 변환된 혈관골격을 시술 중 제공되는 2D영상에 겹쳐 가시화 하였다. 이로써 시술시간 경감과 시술성공률 향상을 유도할 수 있는 시술경로맵을 제시하고자 하였다.

• Geophysics and Geophysical Exploration
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• v.2 no.2
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• pp.77-85
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• 1999

The 3-D seismic research vessel, Tamhae II, was built to raise up the probability of the hydrocarbon discovery in the Korean continental shelf and the first test survey was completed in the East Sea. During the survey, the 240 channel 2-D marine seismic data were acquired by the Korean flag vessel for the first time. Tamhae II has been equipped with source, receiver, recording equipment, and navigation equipment as well as an onboard processing system. The source is composed of four subarrays and each subarray has six airguns. Total airgun volume is 4578 $in^3$. The receiver consists of two sets of 3 km long 240 channel streamer. In the first survey, the successful acquisition of 2-D seismic data was accomplished. From the result of the data processing, we confirmed that the high quality seismic data were acquired. For the high quality data acquisition, technology of survey design and planning, operation of vessel and equipments and systematic quality control should be developed.

• Journal of Oriental Neuropsychiatry
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• v.12 no.2
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• pp.95-102
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• 2001

1. Purpose : The present study was carried out to evaluate the effects of simultaneous treatment with acupuncture, herb medication and non-invasive laser irradiation of blood vessel on the pain control of primary headache. 2. Methods : 30 outpatients who visited in the oriental medical hospital of Kyungsan University from April 10, 2001 to Oct. 10, 2001, based on symptoms and the results of pulse diagnosis, stress test(ABR-2000) and iridology test, were observed on the pain control of primary headache like tension or stress-induced headache. 1)Acupuncture and herbal medicine : Acupuncture treatment and herb medication widely used for headache were carried out simultaneously. 2)Non-invasive laser irradiation : Laser irradiation was undertaken on brachial vein with Lapex-2000 for 30minutes a day for 5 to 15days. 3. Result and Conclusion: In patients with headache, triglyceride mean values decreased from $168.57{\pm}26.90mg/dL$ to $154.23{\pm}28.66mg/dL$ and total cholesterol mean values decreased from $202.23{\pm}22.17mg/dL$ to $194.57{\pm}19.32mg/dL$, after simultaneous treatment with acupuncture, herb medication and non-invasive laser irradiation of blood vessel. And these results suggest that these simultaneous treatment has significant effects in tension and stress-induced headache.: Experiment subjects considered as shown the validity in the headache estimated 80%.

• International Journal of Naval Architecture and Ocean Engineering
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• v.8 no.6
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• pp.537-553
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• 2016

This paper addresses the safety of two-row tank design by performing the extensive sloshing model tests. Owing to the uncertainties entangled with the scale law transforming the measured impact pressure up to the full scale one, so called comparative approach was taken to derive the design sloshing load. The target design vessel was chosen as 230 K LNG-FPSO with tow-row tank arrangement and the reference vessel as 138 K conventional LNG carrier, which has past track record without any significant failure due to sloshing loads. Starting with the site-specific metocean data, ship motion analysis was carried out with 3D diffraction-radiation program, then the obtained ship motion data was used as 6DOF tank excitation for subsequent sloshing model test and analysis. The statistical analysis was carried out with obtained peak data and the long-term sloshing load was determined out of it. It was concluded that the normalized sloshing impact pressure on 230 K LNG-FPSO with two-row tank arrangement is higher than that of convectional LNG carrier, hence requires the use of reinforced cargo containment system for the sake of failure-free operation without filling limitation.

• Nuclear Engineering and Technology
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• v.53 no.10
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• pp.3182-3195
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• 2021

The implementation and validation of multi-dimensional (multi-D) features in thermal-hydraulic system codes aims to extend the application of these codes towards multi-scale simulations. The main goal is the simulation of large-scale three-dimensional effects inside large volumes such as piping or vessel. This novel approach becomes especially relevant during the simulation of accidents with strongly asymmetric flow conditions entailing density gradients. Under such conditions, coolant mixing is a key phenomenon on the eventual variation of the coolant temperature and/or boron concentration at the core inlet and on the extent of a local re-criticality based on the reactivity feedback effects. This approach presents several advantages compared to CFD calculations, mainly concerning the model size and computational efforts. However, the range of applicability and accuracy of the newly implemented physical models at this point is still limited and needs to be further extended. This paper aims at contributing to the validation of the multi-D features of the system code ATHLET based on the simulation of the Tests 1.1 and 2.1, conducted at the test facility ROCOM. Overall, the multi-D features of ATHLET predict reasonably well the evolution from both experiments, despite an observed overprediction of coolant mixing at the vessel during both experiments.

• 한국가시화정보학회:학술대회논문집
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• 2004.12a
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• pp.15-23
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• 2004

The present study is aimed to achieve dynamic visualization from the in-house 3-D stereoscopic PIV to represent quantitative flow information such as time-resolved 3-D velocity distribution, vorticity, turbulent intensity or Reynolds stresses and so on. One of the application of the present study is Leading edge extension(LEX) flow appearing on modern delta wing aircraft. The other is mixing flow in stirring tank used in industry field. LEX in a highly swept shape applied to a delta wing features the modern air-fighters. The LEX vortices generated upon the upper surface of the wing at high angle of attack enhance the lift force of the delta wing by way of increased negative suction pressure over the surfaces. The present method resolves also the complicated flow patterns of two type impellers rotating in stirring vessel. Flow quantities such as three velocity vector components, vorticity and other flow information can be easily visualized via the 3D time-resolved post-processing visualization. And it makes the easy understanding of the unsteady flow characteristics of the typical industrial mixers.

• Journal of the Korean Society of Systems Engineering
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• v.13 no.1
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• pp.15-23
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• 2017

This paper describes verification of APR1400 reactor vessel by applying the system engineering approach, in which the design re-engineering method is used to check the design parameters of APR1400 RV (reactor vessel). The RV is classified as safety class 1 and therefore must adhere strictly to the rules of ASME BPVC section III, subsection NB and seismic category I. This study explores designing the RV by following the ASME guidelines and making a comparative study with the current design. To meet this objective we apply system engineering methodologies to structure the process and allow for verification and validation of the major RV design parameters such as thickness of RV. The structural thicknesses of various part of RV are determined as well as reinforcements on the RV major nozzles. A 3D virtual reality model was created based on the design parameters using CATIA V5 and animation using Dassault Composer V2016. A comparison of re-engineered ARP1400 RV and standard APR1400 RV was done to show which design parameters were taken more conservative approach.