• Transactions of the Korean Society of Mechanical Engineers A
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• v.39 no.3
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• pp.319-325
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• 2015

High-strength steel has replaced mild steel as the material of choice for truck decks or frames, owing to the growing demand for lightweight vehicles. Although studies on the weld fatigue characteristics of mild steel are available, studies on high-strength steels have been seldom conducted. In this study, firstly, we surveyed a chosen number of approaches and selected the Radaj method, which uses the notch factor approach, as the one suitable for evaluating the fatigue life of commercial vehicles. Secondly, we obtained the S-N curves of HARDOX and ATOS60 steel welds, and the F-N curves of the T-weld and overlapped-weld structures. Thirdly, we acquired a general S-N curve of welded structures made of high-strength steel from the F-N curve, using the notch factor approach. Fourthly, we extracted the weld fatigue characteristics of high-strength steel and incorporated the results in the database of a commercial fatigue program. Finally, we compared the results of the fatigue test and the CAE prediction of the example case, which demonstrated sufficiently good agreement.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.6
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• pp.37-43
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• 2017

This review investigates the basic principle of physical interactions and failure mechanisms introduced in the materials and inner parts of semiconducting components under electromagnetic pulses (EMPs). The transfer process of EMPs at the semiconducting component level can be explained based on three layer structures (air, dielectric, and conductor layers). The theoretically absorbed energy can be predicted by the complex reflection coefficient. The main failure mechanisms of semiconductor components are also described based on the Joule heating energy generated by the coupling between materials and the applied EMPs. Breakdown of the P-N junction, burnout of the circuit pattern in the semiconductor chip, and damage to connecting wires between the lead frame and semiconducting chips can result from dielectric heating and eddy current loss due to electric and magnetic fields. To summarize, the EMPs transferred to the semiconductor components interact with the chip material in a semiconductor, and dipolar polarization and ionic conduction happen at the same time. Destruction of the P-N junction can result from excessive reverse voltage. Further EMP research at the semiconducting component level is needed to improve the reliability and susceptibility of electric and electronic systems.

• Journal of KIISE:Software and Applications
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• v.36 no.10
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• pp.800-815
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• 2009

Recently, Web services based service-oriented architecture is widely used to integrate effectively various applications distributed on the networks. In the service-oriented architecture BPEL as a standard modeling language for the business processes provides the way to integrate various services provided by applications. Over the past few years, some types of studies have been made on testing compatibility of services and on discriminating and tracing of the business processes in the services composition. Now a lot of studies about the services composition with BPEL are going on. However there were few efforts to solve the problems caused by the services composition. Especially, there is no effort to evaluate whether a composite service is reliable and whether it is robust against to exceptional situations. In this paper, we suggest a test framework and a testing method for robustness of the composite service written in WS-BPEL. For this, firstly we extract some information from the BPEL process and the participant services. Next, with the extracted information we construct the virtual testing environment that generates various faults and exceptional cases which may be raised within the real services. Finally the testing work for robustness of a composite service is performed on the test framework.

• Journal of Satellite, Information and Communications
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• v.11 no.4
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• pp.1-9
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• 2016

This paper was studied in two ways with respect to the information received from the video signal separation technique of PPI Scop radar device. The proposed technique consists in generating an image signal through the video signal separation and synthesis, symbol generation, the residual image signal generation process. This technology can greatly improve the operating convenience with improved ease of discrimination, screen readability for the operator in analyzing radar information. The first proposed method was constructed for high-speed FPGA-based information processing systems for high speed operation stability of the system. The second proposed method was implemented intelligent algorithms and a software algorithm function curve associated resources.This was required to meet the constraints on the radar information, analysis system. Existing radar systems have not the frame data analysis unit image. However, this study was designed to image data stored in the frame-by-frame analysis of radar images with express information MPEG4 video. Key research content is to highlight the key observations expresses the target, the object-specific monitoring information to the positive image processing algorithm and the function curve delays. For high-definition video, high-speed to implement data analysis and expressing a variety of information was applied to the ARM Processor Support in Pro ASIC3.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.20 no.3
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• pp.129-134
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• 2020

Moisture infiltration inside the solar cell module, filling of EVA sheet, melting of the frame seal, and deterioration of power generation performance in the module one year after installation are occurring. Whitening phenomenon, electrode corrosion phenomenon, and dielectric breakdown phenomenon are appearing in solar cell module installed in Korea before 5-7 years, leading to deterioration of power generation performance, and big problems for long-term reliability and long life technology are emerging. Therefore, in order to solve these problems, the development of a micro inverter (MiCrco Inverter Converter, MiC) including the function of securing the durability of the solar cell module and monitoring the aging progress and the solar cell based on the monitoring data from the MiC smart monitoring programs have been proposed to determine the aging of modules. In addition, in order to become a highly efficient solar smart monitoring system through systematic operation management through IT convergence with MiC that has enhanced monitoring function of solar cell module, SoC(System On Chip) in micro inverter is the environment for solar cell module. There is a demand for functions that can detect information in a complex manner and perform communication and control when necessary. Based on these requirements, this paper aims to develop SoC-based low-cost MiC smart photovoltaic system technology.

• International Commerce and Information Review
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• v.14 no.1
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• pp.171-195
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• 2012

This paper is aimed to prepare some policy-measures which is helpful for China Money FDI in Korea by analysing FDI-related data and political strength and weakness between the two countries and studying fundamental preconditions required for Korea's China Money FDI strategies. As the result of research, key preconditions found out can be summarized as follows; First, because China-Korea economic relationship is largely insufficient in a complementary view as well as in a cooperative state level, Korea should remove the threats in advance that could lead two countries to unlimited competition, and then expand to a relationship of trust between China and Korea. Second, Korea, at least from the perspective of China, may not be an attractive investment destination. Therefore, it is necessary to take advantage of Korea's FTA-expansion-strategy opportunities such as Korea-US FTA which has entered into force recently. Third, because China always has a lot of alternative investment opportunities among world instead of Korea, so Korea should not overlook the fact that China has the bargaining power in large part related on the investment conditions in Korea, such as investment field, investment size, how to invest China Money to Korea, etc. Fourth, if Korea's FDI policy is trapped in the existing rules of the political frame, and moreover Korea can not have the role of rule breaker, it will be difficult to expect Korea's China Money FDI results compared to those efforts. Fifth, if Korea will execute China Money FDI strategies in the context of overestimating the China Power or China Money, it should be noted that Korea may have unexpected losses lead to a national by reason of outward and quantitative investment or bad investment.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.17 no.7
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• pp.1589-1596
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• 2013

Recently, spectral efficiency or reliability is required to be improved in the scenario of multiple access. In this paper, we consider a scenario where two source nodes access one destination node. Different with conventional multiple access studies, in our research, a part of the allocated resource is shared by two source nodes and this scheme is called partial multiplexing. Let $R_s$ denote the ratio of the amount of the shared resource to that of the resource allocated to each user. We analyze and optimize the performance of the partial multiplexing in term of $R_s$. We show that the optimal $R_s$ to maximize the throughput is 1 or 0 based on approximated bit error rate (BER). In addition, if we set a constraint on frame error rate (FER), $R_s$ can have a value between 0 and 1. We also find the approximated $R_s$ to meet the constraint as a closed form. Partial multiplexing can be a novel multiple access scheme.

• Information Systems Review
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• v.13 no.1
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• pp.33-59
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• 2011

Although online social network services widely used in human networking and recruiting industries, it is showing off its limitations in followings-it's hard to reach the status of seamless connection between offline and online; the incompletion and low credibility of the information came from non-face-to-face profile exchange; and the restraint of user autonomy due to centralized control. This paper defines the ubiquitous social network management which enables the seamless real-time face-to-face social interactions of the users based on WPAN (Wireless Personal Area Network) who share the same interest in real word and deduces a ubiquitous social network management framework based on it. As an instance of ubiquitous social network management, u-Recruiting service model will be designed and analyzed. The Analysis using the business model will be followed by the possible scenario of service model. The role, value proposition and potential benefits of the each participants in this service model and will be given as well. In order to evaluate relative advantages of the model suggested by this study, 6 cases will be compared.

• The Korean Journal of Applied Statistics
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• v.30 no.4
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• pp.539-553
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• 2017

We propose a multi-state model to analyze semi-competing risks data with interval-censored or missing intermediate events. This model is an extension of the three states of the illness-death model: healthy, disease, and dead. The 'diseased' state can be considered as the intermediate event. Two more states are added into the illness-death model to incorporate the missing events, which are caused by a loss of follow-up before the end of a study. One of them is a state of the lost-to-follow-up (LTF), and the other is an unobservable state that represents an intermediate event experienced after the occurrence of LTF. Given covariates, we employ the Lin and Ying additive hazards model with log-normal frailty and construct a conditional likelihood to estimate transition intensities between states in the multi-state model. A marginalization of the full likelihood is completed using adaptive importance sampling, and the optimal solution of the regression parameters is achieved through an iterative quasi-Newton algorithm. Simulation studies are performed to investigate the finite-sample performance of the proposed estimation method in terms of empirical coverage probability of true regression parameters. Our proposed method is also illustrated with a dataset adapted from Helmer et al. (2001).

• The Journal of Korean Institute of Communications and Information Sciences
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• v.41 no.1
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• pp.132-139
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• 2016

This study was carried out near the waters of Jango port, Dangjin-gun, Chungcheongnam-do by utilizing 10kHz carrier frequency, for the purpose of measurement and analysis of underwater channel environment of the Western sea. For the measurement of horizontal channel environment, the separation distance between transmitter and receiver is made differently in the range between 10m and 4000m. Meanwhile, for the measurement of vertical channel environment, transmission and receiving side ships are fixed as contacted each other and measured differently depending on their depth of submergence. In this study, the Coherence Bandwidth and the Coherence Time were estimated by analyzing the Power delay profile of the real sea based on the measured data, and analyzing the doppler frequency through frequency conversion of received tone-signal, respectively. This study is expected to become a base study in carrying out the frame design for underwater communication to improve the communication and secure the reliability of communication in future underwater channel environment.