• Journal of Mechanical Science and Technology
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• v.20 no.7
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• pp.1030-1042
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• 2006

An experimental study has been performed to investigate the off-take phenomena at the header-feeder systems (horizontal header pipe with multiple feeder branch pipes) in a CANDU (CANadian Deuterium Uranium) reactor with the branch orientation varies ${\pm}36^{\circ}\;or\;{\pm}72^{\circ}$. In order to evaluate the applicability of the conventional correlations used in the safety analysis code, RELAP5-Mod3, the test facility is designed with the 1/2 scale of the. CANDU 6. It was found that the data set for the top, bottom and side branches are in a good agreement with the correlations used. However, for the specific angled branches, ${\pm}36^{\circ}\;and\;{\pm}72^{\circ}$, the onsets of off-take data and quality data showed large deviation with the conventional model inside RELAP5-MOD3. Furthermore, based on the uncertainty analysis, the conventional 2.5 power law needs to be modified. The present experimental data set can be useful for the construction of the general correlation considering the arbitrary branch orientation.

• Journal of Life Science
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• v.12 no.2
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• pp.53-56
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• 2002

The baculovirus expression vector system (BEVS) is one of the powerful heterologous protein expression systems using insect cells. As a result this has become a hot issue in the fleld of biotechnology. The advantage of the BEVS is that the large-scale production of heterologous proteins, which undergo posttranslational modification in the endoplasmic reticulum (ER), can be accomplished. Altrough posttranslational modification of heterologous proteins in insect cells is more similar to mammalian cells than yeast, it is not always identical. Therefore, aggregation and degradation can sometimes occur in the ER. To produce a high level of bioactive heterologous proteins using BEVS in insect cells, the prerequisite is to completely understand the posttranslational conditions that determine how newly synthesized polypeptides are folded and assembling with ER chaperones in the ER lumen. Here, we provide information on current BEVS problems and the possibility of successful heterologous protein production from mammalian cells.

• Smart Structures and Systems
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• v.4 no.4
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• pp.391-406
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• 2008

This study attempts to develop a real-time debonding monitoring system for carbon fiber-reinforced polymer (CFRP) strengthened structures by continuously inspecting the bonding condition between the CFRP layer and the host structure. The uniqueness of this study is in developing a new concept and theoretical framework of nondestructive testing (NDT), in which debonding is detected without relying on previously-obtained baseline data. The proposed reference-free damage diagnosis is achieved based on the concept of time reversal acoustics (TRA). In TRA, an input signal at an excitation point can be reconstructed if the response signal measured at another point is reemitted to the original excitation point after being reversed in the time domain. Examining the deviation of the reconstructed signal from the known initial input signal allows instantaneous identification of damage without requiring a baseline signal representing the undamaged state for comparison. The concept of TRA has been extended to guided wave propagations within the CFRP-strengthened reinforced concrete (RC) beams to improve the detectibility of local debonding. Monotonic and fatigue load tests of large-scale CFRP-strengthened RC beams are conducted to demonstrate the potential of the proposed reference-free debonding monitoring system. Comparisons with an electro-mechanical impedance method and an inferred imaging technique are provided as well.

• Smart Structures and Systems
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• v.22 no.2
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• pp.201-207
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• 2018

This paper proposes a line laser thermography scanning (LLTS) system for multiple crack evaluation on a concrete structure, as the core technology for unmanned aerial vehicle-mounted crack inspection. The LLTS system consists of a line shape continuous-wave laser source, an infrared (IR) camera, a control computer and a scanning jig. The line laser generates thermal waves on a target concrete structure, and the IR camera simultaneously measures the corresponding thermal responses. By spatially scanning the LLTS system along a target concrete structure, multiple cracks even in a large scale concrete structure can be effectively visualized and evaluated. Since raw IR data obtained by scanning the LLTS system, however, includes timely- and spatially-varying IR images due to the limited field of view (FOV) of the LLTS system, a novel time-spatial-integrated (TSI) coordinate transform algorithm is developed for precise crack evaluation in a static condition. The proposed system has the following technical advantages: (1) the thermal wave propagation is effectively induced on a concrete structure with low thermal conductivity of approximately 0.8 W/m K; (2) the limited FOV issues can be solved by the TSI coordinate transform; and (3) multiple cracks are able to be visualized and evaluated by normalizing the responses based on phase mapping and spatial derivative processes. The proposed LLTS system is experimentally validated using a concrete specimen with various cracks. The experimental results reveal that the LLTS system successfully visualizes and evaluates multiple cracks without false alarms.

• International Journal of Internet, Broadcasting and Communication
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• v.8 no.3
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• pp.12-24
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• 2016

Recently, as the price per bit is decreasing at a fast rate, flash memory is considered to be used as primary storage of large-scale database systems. Although flash memory shows off its high speeds of page reads, however, it has a problem of noticeable performance degradation in the presence of increasing update workloads. When updates are requested for pages with random page IDs, in particular, the shortcoming of flash tends to impair significantly the overall performance of a flash-based database system. Therefore, it is important to have a way to efficiently update the B+-tree, when it is stored in flash storage. This is because most of updates in the B+-tree arise at leaf nodes, whose page IDs are in random. In this light, we propose a new flash B+-tree that stores up-to-date versions of leaf nodes in sibling-leaf blocks (SLBs), while updating them. The use of SLBs improves the update performance of B-trees and provides the mechanism for fast key range searches. To verify the performance advantages of the proposed flash B+-tree, we developed a mathematical performance evaluation model that is suited for assessing B-tree operations. The performance comparisons from it show that the proposed flash B+-tree provides faster range searches and reduces more than 50% of update costs.

• Journal of Digital Contents Society
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• v.10 no.4
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• pp.485-492
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• 2009

In these days mobile handsets have come to be used at almost every user. The mobility of mobile devices and the performance improvement of the mobile networks have made this trend possible. As a great variety of mobile applications are published, the necessity of running large-scale mobile applications becomes greater than before. To accomplish this, the existing researchers have developed mobile cluster computing libraries like Mobile-JPVM. In this paper, we implement a compute-intensive Animated GIF generating application and its cell phone viewer software using Mobile-JPVM library. We find out by the real execution of our softwares on the KTF handsets that they can sufficiently run on cellular phones. Our Animated GIF generator and its viewer are going to be commercially used for the mobile fashion advertisement systems.

• Journal of Digital Contents Society
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• v.10 no.4
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• pp.625-632
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• 2009

In these days mobile handsets have come to be used at almost every user. The performance improvement of mobile devices and networks have made this trend possible. As a great variety of mobile applications are published, the necessity of running large-scale mobile applications becomes greater than before. To accomplish this, the existing researchers have developed mobile cluster computing libraries like Mobile-JPVM. In this paper, we implement a compute-intensive Animated GIF generating application and its cell phone viewer software using Mobile-JPVM library. We find out by the real execution of our softwares on the KTF handsets that they can sufficiently run on cellular phones. Our Animated GIF generator and its viewer are going to be commercially used for the mobile fashion advertisement systems.

• Journal of the Korea Society of Computer and Information
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• v.10 no.2 s.34
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• pp.223-229
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• 2005

DRS (Disaster Recovery System) that was invested on a large-scale becomes obsolete when it is neglected for a certain Period of time. Also the DRS can not be accomplished through the duplicated computer systems. When a disaster happens, the normal operation is possible only if the processes that had been being done before the disaster recover without any loss. Therefore the DRS is not a IT project but needs an analysis of whole business Processes and business continuity plans. This paper analyze the present state of DRS of the domestic bank industry and suggests a remedy.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.12 no.7
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• pp.3018-3040
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• 2018

The mobility model is one of the most important factors that impacts the evaluation of any transportation vehicular networking protocols via simulations. However, to obtain a realistic mobility model in the dynamic urban environment is a very challenging task. Several studies extract mobility models from large-scale real data sets (mostly taxi GPS data) in recent years, but they do not consider the statuses of taxi, which is an important factor affected taxi's mobility. In this paper, we discover three simple observations related to the taxi statuses via mining of real taxi trajectories: (1) the behavior of taxi will be influenced by the statuses, (2) the macroscopic movement is related with different geographic features in corresponding status, and (3) the taxi load/drop events are varied with time period. Based on these three observations, a novel taxi mobility model (T-START) is proposed with respect to taxi statuses, geographic region and time period. The simulation results illustrate that proposed mobility model has a good approximation with reality in trajectory samples and distribution of nodes in four typical time periods.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.8 no.1
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• pp.88-94
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• 1998

Korea has been rapidly industrialized during the past 35 years. During this period, Korea has emphasized only production and workers health has been ignored. Workers are most frequently exposed to organic vapors, such as thinners. This study was performed to evaluate worker exposures to organic solvents by size and type of industry. Results are summarized below. Workers were exposed to mixtures of toluene, xylenes, trichloroethylene, n-hexane, acetone, methanol, n-butanol, n-butyl acetate, and MIBK. Considering additive effects of the compounds, exposure indices (EIs) were calculated. It was found that worker exposures to organic solvents were highest in small industries and lowest in large industries. During a day shift, the highest exposure was indicated 3 - 5 p.m. in the afternoon. Workers in small industries had potential exposures exceeding permissible exposure limits for organic solvents. Local exhuast systems were inappropriate and respiratory protective devices were not supplied to the workers in small industries. Neither program for safe use and storage of toxic materials nor program for respirators was found in any of the plants investigated. Based on the results of the study, workers of small scale industries should be considered first in industrial health.