• Journal of Korea Water Resources Association
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• v.39 no.3 s.164
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• pp.241-252
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• 2006

Numerical models for seepage analysis are useful tools to analyze problems and design protection techniques that are related to seepage through a levee. Though every model may have its own limitations and shortcomings, there were no generalized verifications or calibrations for the commercial models. It means that users can run the model and get the result without understanding nor taking any enough training. This paper Investigates applicability and suitability of some seepage numerical models by comparing analytical solutions with experiments in the user's viewpoint. The results showed that it is more desirable to use analyses with unsaturated-unsteady condition rather than those with saturated-steady conditions, since seepage phenomenon of real levees are changed according to water level and soil property. This study also compared the calculated unsteady solutions with the calculated steady solutions for the levee at Koa of the Nakdong River The comparison revealed that as the result, the safety factor of $2.0{\sim}3.5$ has the same effects for seepage protection techniques when they are designed on the basis of steady-state analysis.

• The Journal of Internal Korean Medicine
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• v.30 no.1
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• pp.144-152
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• 2009

Background : Ephedra (Ephedra sinica) has been widely used to treat respiratory disease in traditional medicine of East Asia for over a hundred years. Despite safety concerns raised by some, the use of ephedra in traditional medicine is documented over more than 1,800 years. It is well established that ephedra is one of the central medicines in Korean 'Seseng constitution' medicine. In Sasang constitution medicine, all humans can be divided into one of four types: Soeumin, Soyangin, Taeumin or Taeyangin, and each constitution type has their own typical characteristics. Accordingly, it is hypothesized that the adverse effects of ephedra differ depending on the Sasang constitution classification. Objectives : The aim of this study was to determine adverse effects of ephedra which is classified as a Taeumin herb, and to observe whether the response differs or not. according to Sasang constitution classification. Methods : The study design was a double-blind randomized controlled trial. The subjects were healthy adults 20 - 50 years old who agreed to participate in this study. They were allocated through randomization to either ephedra group (N=55) or placebo group (N=24). where ephedra extract (6 g of dried ephedra) and placebo with similar opaque capsules were given twice for one day. To compare the adverse events of ephedra according to Sasang constitution classification, we analyzed blood pressure (systolic and diastolic), pulse rate, the morning questionnaire, and patient's global assessment scale score for well known adverse events: palpitation, headache, sweating, tiredness, dyspepsia, and dry mouth. Results : After ingestion of ephedra, the pulse rate had a significant increase in all constitution types. The changes of diastolic pressure in Soeumin and the changes of pulse rate in Soeumin, Soyangin and Taeumin had a significant increase in the ephedra over the control group. In the ephedra group, the palpitation and dyspepsia score of the patients' global assessment scale had a significant increase in Soeumin, with palpitation and sweating score increasing in Soyangin. Others observations were insignificant results. Conclusion : The results of this study may confirm that the physical responses or adverse effects of herbs differ for each type of Sasang constitution. Future studies using other herbs will be required to ascertain the herbal drug reaction of Sasang constitutions.

• Journal of Internet Computing and Services
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• v.17 no.6
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• pp.81-91
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• 2016

VANET is one of the most developed technologies many people have considered a technology for the next generation. It basically utilizes the wireless technology and it can be used for measuring the speed of the vehicle, the location and even traffic control. With sharing those information, VANET can offer Cooperative ITS which can make a solution for a variety of traffic issues. In this way, safety for drivers, efficiency and mobility can be increased with VANET but data between vehicles or between vehicle and infrastructure are included with private information. Therefore alternatives are necessary to secure privacy. If there is no alternative for privacy, it can not only cause some problems about identification information but also it allows attackers to get location tracking and makes a target. Besides, people's lives or property can be dangerous because of sending wrong information or forgery. In addition to this, it is possible to be information stealing by attacker's impersonation or private information exposure through eavesdropping in communication environment. Therefore, in this paper we propose Privacy Assurance Architecture for VANET to ensure privacy from these threats.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.9
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• pp.401-406
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• 2016

When measuring live cable faults and their location based on reflectometry, a coupler is placed between the cable and the test system. This coupler prevents damage to the test circuits by indirectly measuring the live voltage of the cable using reflectometry. It also provides a coupling path that allows the transmission and receive signal to pass into the cable. In this study, we design and construct a contact coupler to locate faults in both dead and live cables using reflectometry. The proposed coupler is of the inductive coupling type and is constructed after the calculation of the signal transmission loss by simulation. The performance of the developed coupler is tested by measuring the transmission loss and frequency flatness. The results showed that the transmission signal loss is less than -1.98dB in the frequency bandwidth above 1 Mhz. The reflectometry system was designed based on sequence time domain reflectometry (STDR) and spread spectrum time domain reflectometry (SSTDR) in order to apply it to the detection of faults and their location in live cables and tests on live cables were performed. The test results showed that the proposed coupler can be used in a reflectometry system for live cable fault detection.

• Journal of Distribution Science
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• v.14 no.4
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• pp.111-116
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• 2016

Purpose - A lot of preceeding studies have focused on the pains that might be felt in spending money, that is an important role in getting psychological safety. Money and social resources can be all for consumers, and they are likely to form a substituting relationship with one another. Being motivated by the idea that spending money for others can come with joy if one's objective is accomplished by social support, this paper aimed to explore the mediating role of the perceived money importance and gratitude in the relationship between social support and pleasure in spending for other-gift. Research Design, Data, and Methodology - In this empirical study, the experimental group is expected to receive social support while the control group is composed of those who are usually indulged in reminiscences of their sweethearts. From the college students, 160 experiment participants were selected and 80 participants of them were assigned to control group as well as to experimental group respectively at random. Empirical study for each of the two groups was performed respectively by means of questionnaire survey. Experimental group data and control group data were combined together to be used for testing hypotheses. Linear structural equation model in Amos was used to verify the hypotheses, and Bootstrap was also used to examine whether there were the mediating roles of the perceived money importance and gratitude or not. Results - From the empirical study, following conclusions could be drawn: First, social support of others makes one perceive the importance of money less; Second, social support of others makes one perceive gratitude to others; Third, less perceived importance of money and gratitude to others can make one feel pleasure in spending for other-gift; and Fourth, less perceived importance of money and gratitude to others can partially mediate the effect of social support from others on the pleasure in spending for other-gift. Conclusions - The outcomes of this study might offer theoretic and managerial implications as follow: Even though many hitherto studies have asserted that spending money usually comes with pains, this study discovered that social support might reduce perceived the importance of money but make others feel gratitude and, thus, one would feel joy in spending money to buy gift for others, and made a contribution to the progress of the theory of pleasure in spending for other-gift. This paper also made contributions toward the development of emotion marketing theory by showing that the effect of social support on the pleasure in spending for other-gift could be partially mediated by the perceived the importance of money and gratitude to others. Based on the above conclusions, it may be affirmed that marketers should help consumers perceive the importance of money less, and help feel gratitude to others by pointing up the support of others to consumers in an attempt to accelerate spending for other-gift.

• KIPS Transactions on Computer and Communication Systems
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• v.5 no.4
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• pp.79-86
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• 2016

About 75% of software security incidents are caused by software vulnerability. In addition, the after-market repairing cost of the software is higher by more than 30 times than that in the design stage. In this background, the secure coding has been proposed as one of the ways to solve this kind of maintenance problems. Various institutions have addressed the weakness patterns of the standard software. A new Korean programming language Saesark has been proposed to resolve the security weakness on the language level. However, the previous study on Saesark can not resolve the security weakness caused by the API. This paper proposes a way to resolve the security weakness due to the API. It adopts a static analyzer inspecting dangerous methods. It classifies the dangerous methods of the API into two groups: the methods of using tainted data and those accepting in-flowing tainted data. It analyses the security weakness in four steps: searching for the dangerous methods, configuring a call graph, navigating a path between the method for in-flowing tainted data and that uses tainted data on the call graph, and reporting the security weakness detected. To measure the effectiveness of this method, two experiments have been performed on the new version of Saesark adopting the static analysis. The first experiment is the comparison of it with the previous version of Saesark according to the Java Secure Coding Guide. The second experiment is the comparison of the improved Saesark with FindBugs, a Java program vulnerability analysis tool. According to the result, the improved Saesark is 15% more safe than the previous version of Saesark and the F-measure of it 68%, which shows the improvement of 9% point compared to 59%, that of FindBugs.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.15 no.2
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• pp.36-49
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• 2016

A subway system is one of the major transportation modes at a metropolitan area. When it meets the other lines, the metro station, so-called transferring station, is usually threatened by severe pedestrian congestion and safety issue of transit users including the transportation vulnerable. Although transportation planners forecast travel demand at the beginning, it is not easy to predict pedestrian flows precisely for a long term if land use plans have dramatically changed. Due to expensive costs, structural extension of metro stations is limited. Therefore, it requires efficient and technical improvements as meeting the demand of pedestrian and physical characteristics. In this study, the core mechanism of pedestrian movement-based simulation model was introduced and evacuation scenarios were analyzed with the developed model. As a result, the multiple optimal routes for unexpected events at the solid space of the multiple stories are easily searched through the simulator and in the case of Sadang Station, travel time can be reduced by 60% when the evacuation information and intuitive design are provided.

• Journal of the Korean Electrochemical Society
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• v.22 no.4
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• pp.139-147
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• 2019

Lithium-ion battery (LiB) with high energy density and efficiency has been utilized for the electric vehicle (EV) and energy storage system (ESS) as well as portable devices. However, as explosion accidents have frequently happened till lately, all-solid-state lithium secondary battery (ALSB) began to get in a spotlight because it can secure a very high safety and energy density by substituting flammable organic liquid electrolyte to nonflammable inorganic solid electrolyte. In spite of ALSB's certain merits, it has shown much poorer performance of cells than one of LiB due to some challenges, which have been small or never dealt with in the LiB system. Hence, although plenty of studies made progress to solve them, an approach about design of all-solid-state electrode (ASSE) has been limited on account of difficulty of ALSB's experiments. That is why the virtual 3D structure of an all-solid-state electrode has to be built and used for the prediction of cell performance. In this study, we elucidate how to form the 3D ASSE structure and what to be needed for the simulation of characteristics on ALSB. Furthermore, the ultimate orientation of 3D modeling and simulation for the study of ALSB are briefly suggested.

• International Journal of Naval Architecture and Ocean Engineering
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• v.10 no.2
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• pp.129-140
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• 2018

A residual stress generated in the steel structure is broadly categorized into initial residual stress during manufacturing steel material, welding residual stress caused by welding, and heat treatment residual stress by heat treatment. Initial residual stresses induced during the manufacturing process is combined with welding residual stress or heat treatment residual stress, and remained as a final residual stress. Because such final residual stress affects the safety and strength of the structure, it is of utmost importance to measure or predict the magnitude of residual stress, and to apply this point on the design of the structure. In this study, the initial residual stress of steel structures having thicknesses of 25 mm and 70 mm during manufacturing was measured in order to investigate initial residual stress (hereinafter, referred to as initial stress). In addition, thermal elastic plastic FEM analysis was performed with this initial condition, and the effect of initial stress on the welding residual stress was investigated. Further, the reliability of the FE analysis result, considering the initial stress and welding residual stress for the steel structures having two thicknesses, was validated by comparing it with the measured results. In the vicinity of the weld joint, the initial stress is released and finally controlled by the weld residual stress. On the other hand, the farther away from the weld joint, the greater the influence of the initial stress. The range in which the initial stress affects the weld residual stress was not changed by the initial stress. However, in the region where the initial stress occurs in the compressive stress, the magnitude of the weld residual compressive stress varies with the compression or tension of the initial stress. The effect of initial stress on the maximum compression residual stress was far larger when initial stress was considered in case of a thickness of 25 mm with a value of 180 MPa, while in case of thickness at 70 mm, it was 200 MPa. The increase in compressive residual stress is almost the same as the initial stress. However, if initial stress was tensile, there was no significant change in the maximum compression residual stress.

• Journal of the Korean Society for Railway
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• v.20 no.3
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• pp.400-412
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• 2017

What is particularly noteworthy from Korean and foreign railway tunnel disaster prevention standards is that for the sake of rapid evacuation, more stringent standards for provision of evacuation passages, which require high cost, are being applied. Korean standards stipulate that passage installation should be determined in accordance with the level of risk through a QRA analysis of each tunnel with 1km or longer length. As, however, detailed application criteria as fire occurrence probability, fire occurrence scenario, size of fires and evaluation criteria for level of social risk are not available, additional costs may be incurred due to excessive design. Thus, standards of an appropriate level need to be established. With this backdrop, this study selects detailed application conditions of a reasonable and appropriate level through a study and analysis of relevant documents and analyzes the maximum length of tunnels to which the application of evacuation passages, or the application major evacuation promotion facilities, can be relaxed, together with a QRA analysis of model tunnels (for high speed rail) with different tunnel lengths. In addition, the QRA results on tunnels, including those on the Honam high-speed rail, and analysis results for the model tunnels, are compiled, ; the ultimate results are compared with Korean and other countries' standards related to evacuation promotion facilities, As a result, The appropriateness of application standards are reviewed. These results are expected to be utilized as basic material for establishing a reasonable disaster prevention plan that will consider safety and economies.