• 대한전기학회:학술대회논문집
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• 대한전기학회 1996년도 추계학술대회 논문집 학회본부
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• pp.343-345
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• 1996

In the case of synchronous machines, certain power system disturbances cause current to assume negative values when no static converter is present. But the converter prevents negative current from flowing, so that overvoltages occur. The overvoltages can be effectively limited as crowbar circuit using GTO. The crowbar circuit with current limiting resistor absorbs energy when overvoltage comes from power system repeatedly. The newly proposed circuit is verified through simulation and experiment

• Clinical and Experimental Pediatrics
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• 제58권5호
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• pp.159-164
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• 2015

Most guidelines for chronic urticaria (CU) in infants and children are based on limited pediatric evidence. Current evidence used to guide treatment in children is extrapolated from data focusing on older age groups. CU in children is a different and complex condition than that in adults. Furthermore, there is little published information regarding urticaria in Korean children. The aim of the present article is to review recent research on chronic childhood urticaria and improve the current understanding of its pathogenesis and management. The classification and definition of urticaria in adults also applies to children. CU is defined as a daily occurrence of spontaneous wheals, angioedema, or both for >6 weeks. The precise pathophysiology of CU is unknown and the rates of successful identification of a cause in children with CU vary from 20%-50%. There is no established laboratory test to evaluate the presence of urticaria. The natural course of childhood CU is undetermined, with limited reports discussing long-term outcomes. Second-generation H1 antihistamines are the cornerstone of management, while limited therapeutic drugs are available for adults.

• 한국치위생학회지
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• 제21권6호
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• pp.751-761
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• 2021

Objectives: The purpose of this study was to examine the relationship between limited oral function and cardiovascular disease in adults over 40 years of age. Methods: Data from the Seventh Korean National Health and Nutrition Examination Survey (2016-2018) was used. In this study, 8,766 adults over the age of 40 years were included as study subjects. They completed a health survey which included current prevalence of hypertension, stroke, myocardial infarction, and angina pectoris, as well as information about blood tests, physical measurements, and oral examinations. Statistical analyses were carried out using complex sample cross-tabulation analysis, general linear model, and logistic regression analysis. Results: The study showed that limited oral function was experienced by patients with stroke (61.3%), myocardial infarction (49.1%), cardiovascular disease (38.5%), hypertension (38.1%), and angina (36.4%) (p<0.05). In patients with stroke, the risk of limited oral function was 2.393 times higher than in patients without stroke. Patients with hypertension were 1.233 times more at risk of speaking difficulty than those without hypertension. Conclusions: Limited oral function is associated with cardiovascular disease. To improve oral health, it is necessary to provide integrated, health-based oral care.

• 한국전기전자재료학회논문지
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• 제14권6호
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• pp.505-510
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• 2001

We simulated the current limiting characteristics of a resistive superconducting fault current limiter (SFCL) for a single line-to-ground fault in the 22.9 kV system. The transient current during the fault increased to 6.33 kA, 5.80 kA and 3.71 kA without SFCL at the fault angles 0$^{\circ}$, 45$^{\circ}$ and 90$^{\circ}$, respectively, a resistive SFCL limited effectively the fault current to 2.27 kA in a half cycle without any DC components. The maximum quench resistance of an SFCL, 16Ω was suggested to be appropriate to limit the fault current in the 22.9 kV distribution system, considering the operating cooperation of a protective relay and the current limiting performance of an SFCL.

• 한국전기전자재료학회논문지
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• 제20권10호
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• pp.889-894
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• 2007

We investigated the quench velocity of superconducting fault current limiter (SFCL) dependent on the source voltage. $YBa_2Cu_3O_7$ (YBCO) thin film was used as the current limiting element for SFCL. The analysis on the quench velocity of SFCL is essential to determine the capacity of circuit breaker (CB) or coordinate with CB. Generally, the quench velocity of SFCL is related with the short-circuit current. To change the short-circuit current, in this paper, the amplitude of the power source voltage is adjusted. Through the fault current limiting experiments, the quench velocity of SFCL was confirmed to increase fast as the source voltage increased. On the other hand, the peak limited current was shown to increase with steady rate of increase.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1994년도 추계학술대회 논문집 학회본부
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• pp.114-116
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• 1994

Recently a superconducting fault current limiter(SFCL) has public attentions for the solution of large fault currents of power systems. Though a SFCL has more effective characteristics than the other current limiting devices, there are many problems to apply it to real power systems. For the analysis of transient fault characteristics of the SFCL, we designed and fabricated a inductive SFCL and tested it in 35V line. The superconducting cable of the SFCL was quenched at lower current(49A) than the designed critical current but it limited the fault current to the lower value(150A) than the one expected without SFCL(250A). And within one period the fault current decreased lower than normal laod current.

• 한국정보기술응용학회:학술대회논문집
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• 한국정보기술응용학회 2005년도 6th 2005 International Conference on Computers, Communications and System
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• pp.237-241
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• 2005

We present a device model for organic light emitting diodes(OLEDs) which includes charge injection, transport, recombination, and space charge effects in the organic materials. The model can describe both injection limited and space charge limited current flow and the transition between them. Calculated device current, light output, and quantum and power efficiency are presented for different cases of material and device parameters and demonstrate the improvements in device performance in bilayer devices. These results are interpreted using the calculated spatial variation of the electric field, charge density and recombination rate density in the device. We find that efficient OLEDs are possible for a proper choice of organic materials and contact parameters.

• 대한기계학회논문집A
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• 제25권3호
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• pp.362-368
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• 2001

To design a limiting MCCB (Molded Case Circuit Breaker) mechanism, a dynamic modeling of the mechanism in which the electro-magnetic force effects are incorporated needs to be developed. Conventionally, electro-magnetic effects were considered separately for the design of the mechanism. In this paper, an electro-magnetic force that is induced by limited current is identified and included in the dynamic modeling of the mechanism. Thus, the electro-magnetic which is defined as a external force and the mechanical effects are simultaneously considered for the design of the mechanism which is composed of contactor, spring , link, latch and so on.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제9권10호
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• pp.4177-4190
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• 2015

Current research on Internet of Things (IoT) has primarily addressed the means to enhancing smart resource allocation, automatic network operation, and secure service provisioning. In particular, providing satisfactory security service in IoT systems is indispensable to its mission critical applications. However, limited resources prevent full security coverage at all times. Therefore, these limited resources must be deployed intelligently by considering differences in priorities of targets that require security coverage. In this study, we have developed a new application of Cognitive Radio (CR) technology for IoT systems and provide an appropriate security solution that will enable IoT to be more affordable and applicable than it is currently. To resolve the security-related resource allocation problem, game theory is a suitable and effective tool. Based on the Blotto game model, we propose a new strategic power allocation scheme to ensure secure CR communications. A simulation shows that our proposed scheme can effectively respond to current system conditions and perform more effectively than other existing schemes in dynamically changeable IoT environments.

• International journal of advanced smart convergence
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• 제12권2호
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• pp.135-142
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• 2023

Commercialization of research results plays an important role in the socio-economic development of a country based on science, technology and innovation. However, in recent years, the commercialization of research results by universities in Vietnam remains ineffective because scientists often carry out research on issues they find interesting, and don't listen to enterprises to find out what the latter need. In the other hand, the process of commercializing research results in universities encounters difficulties, including the issue of establishing intellectual property rights the limited quality of research results, and the limited access to capital resources to develop inventions. This paper focuses on analyzing the current challenges of commercialization of research results in universities and propose solutionsto promote commercialization of research results from the universities, suitable to the conditions of Vietnam.