• Journal of the Korean earth science society
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• v.34 no.7
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• pp.615-625
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• 2013

Many eruptions of Mt. Baekdusan volcano have been recorded in the historical literatures, and there were unrest precursors in 2002. Based on the geological survey results, it has been recognized that Mt. Baekdusan's Plinian eruptions had caused ashfall, followed by the occurrence of pyroclastic flows, which were caused by the collapse of eruption column. Therefore, we simulated the range of the impacts of pyroclastic flows, which were caused by small eruptions from a specific crater. Based on the simulation results, it can be interpreted that, when the pyroclastic flows are caused by the eruption column collapse from an eruption with less than VEI 3, the impacts will range from the outer rim of the caldera to the mountain slope 7 km at the maximum distance. Furthermore, it is interpreted that, when the eruption column occurs by the crater located inside the caldera, most will be deposited inside the caldera and what overflows will be deposited thickly mostly in the north valley, the upper stream region of Erdaobaihe.

• Journal of Radiation Protection and Research
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• v.40 no.3
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• pp.168-173
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• 2015

The present investigation was planned to estimate potential possibility of striped field mice, Apodemus agrarius coreae (A. a. coreae), as a biological dosimeter in radio-environmental ecology. We bred captured wild A. a. coreae at laboratory and classified taxonomically based on external, cranial and tooth characters. Organ weights and splenocytic apoptosis were observed in order to establish a basic data on radiation biology of A. a. coreae (male, 40 weeks old). The biological effects was observed at 24hrs following irradiation (doses : 0, 0.5, 1, 2 Gy, dose rate : $0.8Gymin^{-1}$, $^{137}Cs$). Only thymus weights was significantly decreased. Splenocytic apoptosis was increased after irradiation. But splenocytic apoptosis was decreased in 0.5 Gy ${\gamma}$-irradiated mice compared to those of 0, 1, 2 Gy (P < 0.05). These data suggested that events in thymus and spleen of Korean dark-striped field mice, A. a. coreae THOMAS, could be a potential radio-biological indicator in human environments.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.48 no.2
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• pp.135-146
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• 2020

To define an interface in a conventional level-set method, an analytical function must be revealed for an interfacial geometry. However, it is not always possible to define a functional form of level sets when interfaces become complex in a Cartesian coordinate system. To overcome this difficulty, we have developed a new level-set formalism that discriminates the interior from the exterior of a CAD modeled interface by parameterizing the stereolithography (STL) file format. The work outlined here confirms the accuracy and scalability of the hydrodynamic reactive solver that utilizes the new level set concept through a series of tests. In particular, the complex interaction between shock and geometrical confinements towards deflagration-to-detonation transition is numerically investigated. Also, a process of flame spreading and damages caused by point source detonation in a real-sized plant facility have been simulated to confirm the validity of the new method built for reactive hydrodynamic simulation in any complex three-dimensional geometries.

• The KIPS Transactions:PartC
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• v.9C no.4
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• pp.605-614
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• 2002

Amount of the web traffic web server handles are explosively increasing, which requires that the performance of the web server should be improved for the various web services. Although the analysis for the HTTP traffic with the proper tuning for the web server is essential, the research relevant to the subject are insignificant. In particular, although most of applications are implemented over HTTP 1.1 protocol, the researches mostly deal with the performance evaluation of the HTTP 1.0 protocol. Consequently, the modeling approach and the performance evaluation over HTTP 1.1 protocol have not been well formed. Therefore, basing on the HTTP 1.1 protocol supporting persistent connection, we present an analytical end-to-end tandem queueing model for web server to consider the specific hardware configuration inside web server beginning at accepting the user request until completing the service. we compare various performances between HTTP 1.0 and HTTP 1.1 under the overloading condition, and then analyze the characteristics of the HTTP traffic that include file size requested to web server, the OFF time between file transfers, the frequency of requests, and the temporal locality of requests. Presented model is verified through the comparing the server throughput according to varying requests rate with the real web server. Thereafter, we analyze the performance evaluation of the web server, according to the interrelation between TCP Listen queue size, the number of HTTP threads and the size of the network buffers.

• Korean Chemical Engineering Research
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• v.49 no.1
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• pp.41-46
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• 2011

We investigated experimentally the properties of dust explosion through lycopodium particle clouds in a duct to provide the fundamental knowledge. Propagating dust flames in the vertical duct of 120 cm height and 12 cm square cross-section were observed by digital video camera and flame front is visualized using by PIV(Particle Image Velocimetry) system. As the result, when the same average dust concentration existed in the vertical duct, downward flame propagation was faster than the upward flame propagation, its rate increased with dust concentration in 300g/$m^3$. Post flames were caused by the ignition of unburned particles which flowed into the rear region of flame from passage between flame and duct wall, and they generated regardless of duct condition. Also, it was found that appearance frequency of post flames during dust flame propagations increased with the increase of dust concentration.

• Journal of the Economic Geographical Society of Korea
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• v.11 no.3
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• pp.302-318
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• 2008

As socio-economic paradigms have been moving towards the knowledge-based capitalism from the industrial capitalism, it is obvious that research on industrial agglomeration and regional innovation has been explosively increased. However, there is a contradictory tendency that the terms and concepts, which are related to industrial agglomeration, have became less clear and more fuzzy. In this sense, this paper attempts to tackle and reconsider the concept, typology and theories of agglomeration and (or) cluster in economic geography. The main claims are as follows. Firstly, the terms and concepts related to industrial agglomeration and cluster need to be clear. It seems to be that cluster is received as an umbrella concept of agglomerations all-embracing the varieties of a geographical concentration of industry. However, the authors claim that the cluster concept should be part of the diverse types of industrial agglomeration. Secondly, the tendency of a less clear definition on agglomeration and cluster could make it difficult to identify the types of agglomeration being in the forms of diversity. Such a tendency would result in a misguided understanding and interpretation of a typology of agglomeration. Finally and most importantly, as perspectives or theories that are associated with industrial agglomeration and cluster show increasingly a propensity of convergence, it is problematic that related theories and perspectives lose their own identity and distinctiveness.

• Journal of the Korean Geotechnical Society
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• v.37 no.10
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• pp.13-25
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• 2021

The most widely used method for determining the blast effects of explosives is the Trauzl test. This test is used to measure the explosive power (strength) of a substance by determining volume increase, which is produced by the detonation of a tested explosive charge in the cavity of a lead block with defined quality and size. In this paper, Trauzl lead block test and High speed 3D-DIC (Digital Image Correlation) system were conducted to evaluate the stemming effect of the blast hole. The effects of stemming materials can be expressed as the expansion of the cavity in a standard lead block through explosion of the explosives. The blasting experiment was conducted with emulsion explosives. The stemming material in the blast hole of lead block, which was adopted in this study, were using sand and stone chips. Results of blasting experiment and numerical analysis showed that the expansion rates of lead block were most affected by stone chips followed by sand. Also, as result of dynamic strain measurement on the lead block surface of High speed 3D-DIC system, the displacement and surface strain on the block were the highest in the experiment case of stone chips stemming.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.12
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• pp.118-127
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• 2018

The purpose of this study is to identify the relationships between satisfaction, behavioral intention and recommended intention of luxury consumers identified in the preceding study as reasons for the explosive growth in the Korean imported car market. Research results found that brand quality, fashion, self-display, and store atmosphere had positive effects on satisfaction, while independent variables influenced behavioral intention. However, it was found that the store atmosphere did not affect satisfaction. Satisfaction expressed a strong positive effect on behavioral intention. In addition, behavioral intention was shown to positively affect recommendation intention. These results imply that consumers are significantly influenced by psychological factors when purchasing imported cars, and that consumers value psychological factors even when resold or recommended to others. The theoretical implications of the study are the empirical analysis of the consumption factors of imported cars using the existing Luxury consumption factors. The practical implications are to provide the importers with a basis for their marketing strategy. Although there are many studies on quality and service in import car markets, there is a lack of research on relevant psychological factors.

• The Journal of the Korea institute of electronic communication sciences
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• v.16 no.4
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• pp.633-642
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• 2021

Growing demand for electricity, when combined with the need to limit carbon emissions, drives a huge increase in renewable energy industry. In the electric power system, electricity supply always needs to be balanced with electricity demand and network losses to maintain safe, dependable, and stable system operation. There are three broad challenges when it comes to a power system with a high penetration of renewable energy: transient stability, small signal stability, and frequency stability. Transient stability analyze the system response to disturbances such as the loss of generation, line-switching operations, faults, and sudden load changes in the first several seconds following the disturbance. Small signal stability refers to the system's ability to maintain synchronization between generators and steady voltages when it is subjected to small perturbations such as incremental changes in system load. Frequency stability refers to the ability of a power system to maintain steady frequency following a severe system upset resulting in significant imbalance between generation and load. In this paper, we discusses these stability using system simulation by renewable energy deployment plan, and also analyses the influence of the renewable energy sources to the grid stability.

• Journal of Korean Tunnelling and Underground Space Association
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• v.24 no.4
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• pp.305-316
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• 2022

Hydrogen energy is emerging as an alternative to the depletion of fossil fuels and environmental problems, and the use of hydrogen vehicles is increasing in the automobile industry as well. However, since hydrogen has a wide flammability limit of 4 to 75%, there is a high concern about safety in case of a hydrogen car accident. In particular, in semi-enclosed spaces such as tunnels and underground parking lots, a fire or explosion accompanied by hydrogen leakage is highly likely to cause a major accident. Therefore, it is necessary to review hydrogen safety through analysis of flammability areas caused by hydrogen leakage. Therefore, in this study, the effect of the air velocity in the tunnel on the flammability area was investigated by analyzing the hydrogen concentration according to the hydrogen leakage conditions of hydrogen vehicles and the air velocity in the tunnel in a road tunnel with standard section. Hydrogen leakage conditions were set as one tank leaking and three tanks leaking through the TPRD at the same time and a condition in which a large crack occurred and leaked. And the air velocity in the tunnel were considered 0, 1, 2.5, and 4.0 m/s. As a result of the analysis of the flammability area, it is shown that when the air velocity of 1 m/s or more exists, it is reduced by up to 25% compared to the case of air velocity of 0 m/s. But there is little effect of reducing the flammability area according to the increase of the wind speed. In particular, when a large crack occurs and completely leaks in about 2.5 seconds, the flammability area slightly increases as the air velocity increases. It was found that in the case of downward ejection, hydrogen gas remains under the vehicle for a considerably long time.