• Journal of the Computational Structural Engineering Institute of Korea
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• v.34 no.1
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• pp.1-8
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• 2021

Vapor cloud explosions show different characteristics from that caused by ordinary TNT explosives and their loading effect is similar to pressure waves. Typical methods used for blast pressure calculations are the TNT-equivalent method and multi-energy method. The TNT-equivalent method is based on shock waves, similar to a detonation phenomenon, and multi-energy method is based on pressure waves, similar to a deflagration phenomenon. This study was conducted to derive an appropriate blast pressure by applying various plant explosion cases. SDOF analysis and nonlinear dynamic analysis were performed to compare the degree of deformation and damage of the selected structural members for the explosion cases. The results indicated that the multi-energy method was more exact than the TNT-equivalent method in predicting the blast pressure of vapor cloud explosions. The blast pressure of vapor cloud explosion in plants can be more accurately calculated by assuming the charge strength of multi-energy method as 7 or 8.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.34 no.6
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• pp.355-362
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• 2021

Various blast pressure calculation methods have been developed for predicting the explosion pressure of vapor cloud explosions. Empirical methods include the TNT equivalent method, and multi-energy method. The multi-energy method uses a charge strength that considers environmental factors. Although the Kinsella guideline was provided to determine the charge strength, there are limitations such as guidelines related to ignition sources. In this study, we proposed an improved charge strength guideline, by subdividing the ignition source intensity and expanding the type classification through literature analysis. To verify the improved charge strength guideline, and to compare it with the result obtained using the Kinsella guideline, four vapor cloud explosion cases which could be used to estimate the actual blast pressure were investigated. As a result, it was confirmed that the Kinsella guidelines showed an inaccurate, that is, wider pressure than the actual estimated blast pressure. However, the improved charge strength guideline enabled the selection of the intensity of the ignition source, and more subdivided types through the expansion of classification, hence it was possible to calculate the blast pressure relatively close to that of the actual case.

• Journal of Energy Engineering
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• v.24 no.4
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• pp.81-88
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• 2015

In midst of electrical energy consumption on the rise due to the industrial development and the improved quality of living, medium capacity and multi boilers which use gas that is comparatively low cost and can be supplied reliably are simulated for energy consumption using the partial load data obtained from the experiment. Economic analysis that considers initial and operation costs is carried out based on the Annual equal payment method.

• Proceedings of the Korea Multimedia Society Conference
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• 2004.05a
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• pp.251-254
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• 2004

환자의 체동은 MRl에 의해 제공된 화질을 저하시키는 주된 원인이 되고 있다. 본 연구에서는 MRI에 있어서 3차원 강체운동에 기인한 아티팩트를 수정하는 기법을 제안한다. 이러한 목표를 달성하기위해 MR 화상 데이터를 얻기위한 2차원 다-슬라이스 기법(a multiple 2-D slice technique)이 사용되어왔다. 대상물체의 운동에 해당하는 수집된 MRI 데이터는 불균일 표본화와 위상오차에 의해 영향을 받게된다. 3차원 운동에 대해 주어진 운동 파라메타와 장면간의 영향이라는 가정하에 양선형보간법과 중첩법으로 다-슬라이스 데이터를 사용하는 방법에 기반한 재구성 알고리즘을 MRI 아티팩트를 수정하는데 사용한다. 미지의 체동 파라메타들을 추정하기위해 3차원 강체운동은 다-슬라이스 취득기법의 각 영상과 결합된 관심영역 바깥쪽에서의 측정된 에너지를 증가시킨다는 사실을 이용하는 최소에너지법을 적용한다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2007.06a
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• pp.401-405
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• 2007

In sensor network, cluster based routing protocol about efficient energy usage method has researched variously. But existing cluster based routing protocol have problems. one of the problem is sensor nodes's imbalance energy consumption problem at cluster reconstruction. anther is non- connection problem between header node and spc node when they are far from each other, not properly connected. We propose cluster re-division and header node of multihop transmission method in this paper. The cluster re-division method is the method that re-divides existing routing protocol with the small-scale cluster and multihop transmission method is the method regarding the relay transmission between the header nodes. Through the simulation, the proposed routing mechanism shows more excellent than exiting routing protocol in balance energy consumption and energy efficiency.

• Journal of Korea Multimedia Society
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• v.12 no.9
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• pp.1233-1241
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• 2009

Over the 50 percents of women who are older than 45 years have osteoporosis. Because people hardly recognize this disease by themselves, the researches that measure bone mineral density have been doing widely to detect osteoporosis in the early stage. The most widely used methods for bone mineral density measurement are based on the X-ray imaging. Among them, DEXA(Dual-energy X-ray Absorptiometry) imaging is one of the important methods in bone mineral density measurement. DEXA images are useful methods to increase diagnosis efficiency by reducing anatomic noise as two images obtained from two different energy levels. However, it has some problems to a calibration parameter determined by the heuristic method for bone extraction. In this paper, we propose the method to extract bone in DEXA image using calibration parameter based on anatomic attenuation coefficient. The experimental results reveal that the proposed method is effective.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 2005.11a
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• pp.327-330
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• 2005

동적시스템의 공학적 설계는 대부분 구성요소들의 구조적 연결과 요소들의 파라미터들의 결정을 포함하며, 구조와 파라미터 모두 제한이 없는 열려진 특성을 가진다. 본 연구에서는 효율적인 구조/파라미터 탐색을 위한 교대 탐색법을 제안하고 이를 멀티-에너지 도메인 시스템 해석 및 설계에 적합한 본드 그래프를 이용하여 고유값 설계 문제에 적용하였다.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.29 no.6
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• pp.577-582
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• 2016

In this study, a multiscale method for solving a thermoelasticity problem for interphase in the polymeric nanocomposites is developed. Molecular dynamics simulation and finite element analysis were numerically combined to describe the geometrical boundaries and the local mechanical response of the interfacial region where the polymer networks were highly interacted with the nanoparticle surface. Also, the micrmechanical thermoelasticity equations were applied to the obtained equivalent continuum unit to compute the growth of interphase thickness according to the size of nanoparticles, as well as the thermal phase transition behavior at a wide range of temperatures. Accordingly, the equivalent continuum model obtained from the multiscale analysis provides a meaningful description of the thermoelastic behavior of interphase as well as its nanoparticle size effect on thermoelasticity at both below and above the glass transition temperature.

• Journal of the Geological Society of Korea
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• v.54 no.6
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• pp.683-694
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• 2018

Subduction has been the focal point of numerical studies for decades because it plays an important role in the Earth's mass and energy circulations and generates earthquakes and arc volcanoes which are closely related to the human lives. Among the studies on subduction, numerical modeling has been broadly applied to the quantitative studies on the subducting slab in the mantle which cannot be directly observed. In this study, we benchmark the numerical subduction modeling using a finite element package, COMSOL $Multiphysics^{(R)}$ and the results are consistent with the previously reported benchmark results.

• Journal of Internet Computing and Services
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• v.17 no.6
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• pp.17-23
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• 2016

In the future network such as Internet of Things (IoT), the number of computing devices are expected to grow exponentially, and each of the things communicates with the others and acquires information by itself. Due to the growing interest in IoT applications, the broadcasting in Opportunistic ad-hoc networks such as Machine-to-Machine (M2M) is very important transmission strategy which allows fast data dissemination. In distributed networks for IoT, the energy efficiency of the nodes is a key factor in the network performance. In this paper, we propose a fuzzy logic based probabilistic multi-hop broadcast (FPMCAST) algorithm which statistically disseminates data accordingly to the remaining energy rate, the replication density rate of sending node, and the distance rate between sending and receiving nodes. In proposed FPMCAST, the inference engine is based the fuzzy rule base which is consists of 27 if-then rules. It maps input and output parameters to membership functions of input and output. The output of fuzzy system defines the fuzzy sets for rebroadcasting probability, and defuzzification is used to extract a numeric result from the fuzzy set. Here Center of Gravity (COG) method is used to defuzzify the fuzzy set. Then, the performance of FPMCAST is evaluated through a simulation study. From the simulation, we demonstrate that the proposed FPMCAST algorithm significantly outperforms flooding and gossiping algorithms. Specially, the FPMCAST algorithm has longer network lifetime because the residual energy of each node consumes evenly.