• Journal of KIISE:Information Networking
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• v.37 no.6
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• pp.466-476
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• 2010

This paper proposes a novel simulator which is capable of loading different modules enabling to update the simulator easily when the 4G mobile communication technologies are revised. This simulator is not only designed based on IMT-Advanced channel model but also confirmed its reliability through mutual verification with Matlab based simulator developed by Winner+. The proposed simulator was evaluated on the basis of evaluation requirements on the IMT-Advanced. By comparing with experimental results for IEEE and 3GPP, it was also proved for the simulator to have a better performance.

• Proceedings of the KSME Conference
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• 2003.11a
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• pp.1098-1102
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• 2003

Vacuum vessel of the KSTAR(Korea Superconducting Tokamak Advanced Research) tokamak is a fully welded structure with D-shaped cross-section. According to the requirements of the physics design, sixteen horizontal ports, sixteen slanted ports, sixteen baking and cooling ports, and twenty-four top and bottom vertical ports are designed for the diagnostics, plasma heating, vacuum pumping, and baking and cooling. Bellows on these ports are used for flexible components to absorb the relative displacement due to the vacuum vessel thermal expansion and the electromagnetic force between the vacuum vessel and the cryostat ports. Fatigue strength evaluation was performed to decide the dimension of the bellows. In order to assure the quality of the bellows, a prototype bellows for the neutral beam injection port has been fabricated and tested prior to main fabrication. It was conformed that the prototype bellows has sufficient fatigue strength and vacuum reliability in the expected load conditions.

• Journal of Power Electronics
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• v.16 no.2
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• pp.704-716
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• 2016

Small distributed generation units are usually connected to the main electric grid through single-phase voltage source inverters. Grid operating conditions such as voltage and frequency are not constant and can fluctuate within the range values established by international standards. Furthermore, the requirements in terms of power factor correction, total harmonic distortion, and reliability are getting tighter day by day. As a result, the implementation of reliable and efficient control algorithms, which are able to adjust their control parameters in response to changeable grid operating conditions, is essential. This paper investigates the configuration topology and control algorithm of a single-phase inverter with the purpose of achieving high performance in terms of efficiency as well as total harmonic distortion of the output current. Accordingly, a Second Order Generalized Integrator with a suitable Phase Locked Loop (SOGI-PLL) is the basis of the proposed current and voltage regulation. Some practical issues related to the control algorithm are addressed, and a solution for the control architecture is proposed, based on resonant controllers that are continuously tuned on the basis of the actual grid frequency. Further, intentional islanding operation is investigated and a possible procedure for switching from grid-tied to islanding operation and vice-versa is proposed.

• Journal of Information Processing Systems
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• v.12 no.3
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• pp.489-501
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• 2016

As interest in the Internet increases, related technologies are also quickly progressing. As smart devices become more widely used, interest is growing in words are missing here like "improving the" or "figuring out how to use the" future Internet to resolve the fundamental issues of transmission quality and security. The future Internet is being studied to improve the limits of existing Internet structures and to reflect new requirements. In particular, research on words are missing here like "finding new forms of" or "applying new forms of" or "studying various types of" or "finding ways to provide more" reliable communication to connect the Internet to various services is in demand. In this paper, we analyze the security threats caused by malicious activities in the future Internet and propose a human behavior analysis-based security service model for malware detection and intrusion prevention to provide more reliable communication. Our proposed service model provides high reliability services by responding to security threats by detecting various malware intrusions and protocol authentications based on human behavior.

• Transactions of the Korean Society of Automotive Engineers
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• v.20 no.5
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• pp.95-101
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• 2012

An electric water pump for engine cooling system has an advantage which particularly in the cold start, the use of the electric water pump saves fuel and leads to a corresponding reduction in emissions. The canned type electric water pump without mechanical sealing elements was selected to meet the requirements for operational reliability and life. However, the electric water pump for internal combustion engine generates much more heat loss than for hybrid electric vehicle since it is operated by the electric power of high current and low voltage. In this study, the fluid flow and thermal characteristics of the canned type electric water pump as an inverter integrated water pump has been investigated under the effects of heat generation. The analysis conditions such as outdoor air temperature of $125^{\circ}C$, water pump speed of 6000 rpm, coolant temperature of $106^{\circ}C$ and coolant flow rate of 120 L/min was used as a standard condition. Therefore, flow fields and temperature distribution inside the water pump were obtained. Also, we checked the feasibility of the canned type for the electric water pump in comparison with the mechanical seal type.

• Fashion & Textile Research Journal
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• v.13 no.1
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• pp.55-65
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• 2011

The purposes of this study were to measure Shangri-La Syndrome through the difference age(i.e. chronological age-cognitive age) of Korean in their 40s and 50s, and to examine the variables which have an effect on the syndrome, requirements of Shangri-La Syndrome and means to look young. The research was conducted on 365 men and women in their 40s and 50s from Ulsan, Busan, and Seoul. The statistical analysis methods used for the study were reliability analysis, factor analysis, frequencies analysis, t-test, correlation analysis, ANOVA, Duncan test, and regression analysis. The results of this study are as follows : First, difference age showed to be 9.5 on the average and appeared to be largest in terms of feel and interests ages and smallest in terms of look and health ages. Second, it was found that Shangri-La Syndrome was influenced by health and self-love factors from among physical and social-psychological characteristics, and age, educational status, job, and hobby out of demographic characteristics. Third, it was shown that health body was the most important condition for a living with Shangri-La Syndrome and clothing was the most effective tool available for young appearances.

• Journal of the Korean Society for Precision Engineering
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• v.23 no.7 s.184
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• pp.130-137
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• 2006

TFT-LCD(Thin Film Transistor Liquid Crystal Display) module is representative commercial product of FPD(Flat Panel Display). Thickness of TFT-LCD module is very thin. It is adopted for major display unit for IT devices such as Cellular Phone, Camcorder, Digital camera and etc. Due to the harsh user environment of mobile IT devices, it requires complicated structure and tight assembly. And user requirements for the mechanical functionalities of TFT-LCD module become more strict. However, TFT-LCD module is normally weak to high level transient mechanical shock. Since it uses thin crystallized panel. Therefore, anti-shock performance is classified as one of the most important design specifications. Traditionally, the product reliability against mechanical shock is confirmed by empirical method in the design-prototype-drop/impact test-redesign paradigm. The method is time-consuming and expensive process. It lacks scientific insight and quantitative evaluation. In this article, a systematic design evaluation of TFT-LCD module for mobile IT devices is presented with combinations of FEA and testing to support the optimal shock proof display design procedure.

• Proceedings of the KWS Conference
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• 2005.11a
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• pp.82-84
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• 2005

Fatigue assessment of welded structure is very sensitive to the method of local stress determination. Normally, hot spot stress which is surface stress extracted from 0.5t, 1.5t away from weld toe is widely used to obtain local stress. However, this method has a lot of limitation in the evaluation of fatigue strength. Therefore, mesh has to comply with strict requirements since stress extracted from this method strongly rely on mesh size and element types. And that method does not cover the stress gradient through thickness direction since only surface stress is considered. Recently, new method to obtain local stress is proposed, which is structural stress. This method has an advantage, which is mesh intransitiveness and covering the effect of both bending and axial stress in local area. In this paper, fatigue test data for various welded joints was analyzed to review the reliability of structural stress. As a result, it is verified that S-N curve using structural stress guaranteed single master curve for various joint type and testing condition.

• Journal of Korean Society on Water Environment
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• v.28 no.3
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• pp.359-366
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• 2012

Accurate predictions about the water quality of a river have great importance in identifying in-stream flow and water supply requirements and solving relevant environmental problems. In this study, the effect of water release from upstream dam on the downstream water quality has been investigated by applying a hydological model combined with QUAL2E to Geum River basin. The ESP (Ensemble Stream Prediction) method, which has been validated and verified by lots of researchers, was used to predict reservoir and tributary inflow. The input parameters for a combined model to predict both hydrological characteristics and water quality were identified and optimized. In order to verify the model performance, the simulated result at Gongju station, located at the downstream from Daecheong Dam, has been compared with measured data in 2008. As a result, it was found that the proposed model simulates well the values of BOD, T-N, and T-P with an acceptable reliability.

• Korean Journal of Organic Agriculture
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• v.27 no.2
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• pp.111-132
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• 2019

Recently farming succession has become an important topic in agriculture in order to secure agricultural manpower in response to the aging of farming households and declining population. This study investigates farmers and agricultural college students' perception of farming succession in Korea, especially of farming succession to a third party. Farmers and agricultural college students are potential farming transferors and successors, respectively. We surveyed 146 farmers and 95 students who graduated or were studying at the Korea National College of Agriculture and Fisheries. The questions of the survey are largely divided into four categories: 1) the will and scope of farming transfer and succession, 2) the requirements for the successors of farming, 3) the perception on the succession to third-parties, and 4) the farming succession policy. According to the survey results 41.4% of farmers and 46.3% of potential farming successors have willingness to accept a farming succession to a third party. When farming succession was carried out through the Farming Succession Exchange, 46.8% of farmers and 54.7% of successors said they are willing to carry out third-party farming succession. This means that a third-party farming succession could be activated if the reliability issue that may arise during the farming succession is resolved through the Farming Succession Exchange. Other implications for farming succession are suggested at the end of this study.