• Journal of the Korean Operations Research and Management Science Society
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• v.32 no.4
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• pp.1-18
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• 2007

In this paper, we develop an adaptive genetic algorithm (aGA). The aGA has an adaptive scheme which can automatically determine the use of local search technique and adaptively regulate the rates of crossover and mutation operations during its search process. For the adaptive scheme, the ratio of degree of dispersion resulting from the various fitness values of the populations at continuous two generations is considered. For the local search technique, an improved iterative hill climbing method is used and incorporated into genetic algorithm (GA) loop. In order to demonstrate the efficiency of the aGA, i) a canonical GA without any adaptive scheme and ii) several conventional aGAs with various adaptive schemes are also presented. These algorithms, including the aGA, are tested and analyzed each other using various test problems. Numerical results by various measures of performance show that the proposed aGA outperforms the conventional algorithms.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.7
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• pp.1263-1269
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• 2009

Stable and sustainable power supply means maintaining a certain level of power quality and service while securing energy resource and resolving environmental issues. Distributed generation (DG) has become an essential and indispensable element from environmental and energy security perspectives. It is known that voltage violation is the most important constraint for load variation and the maximum allowable DG. In distribution system, sending voltage from distribution substation is regulated by ULTC (Under Load Tap Changer) designed to maintain a predetermined voltage level. ULTC is controlled by LDC (Line Drop Compensation) method compensating line voltage drop for a varying load, and the sending voltage of ULTC calls for LDC parameters. The consequence is that the feasible LDC parameters considering variation of load and DG output are necessary. In this paper, we design each LDC parameters determining the sending voltage that can satisfy voltage level, decrease ULTC tap movement numbers, or increase DG introduction. Moreover, the maximum installable DG capacity based on each LDC parameters is estimated.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.54 no.5
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• pp.212-216
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• 2005

This paper describes the application scheme of resistive HTS-FCL(High Temperature Superconducting-Fault Current Limiter) on future new distribution system. Future new distribution system means the power system to which applies the 22.9kV HTS cable with low-voltage and mass-capacity characteristics replacing the 154kv conventional cable in addition to HTS transformer and HTS-FCL. The fault current of future new distribution system will increase greatly because of the inherent characteristics of HTS transformer/cable and applications of distributed generations and spot networks and so on. This means that the HTS-FCL is necessary to reduce the fault current below the breaking capacity. This paper studies the appropriate location, parameters and the influences of HTS-FCL on future new distribution system. Finally, this paper suggests the reasonable basic parameters of resistive HTS-FCL for future KEPCO new distribution system.

• Proceedings of the KIEE Conference
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• 2005.05a
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• pp.96-98
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• 2005

This paper describes a monitoring system that monitors power quality and undesirable accidents when distributed generations are connected to the power grid. Prior to develop and operate a physical monitoring system, we constitute a simulation device to simulate the monitoring processes for the situations. The simulation system consists of the server and the client that connected by communication line. This system has various functions to monitor the power quality and the connection situation. Those functions are generation, transmission, acquisition and analysis of the simulated power data. This research seems very important to get the reliable and intelligent connection algorithm through the result of simulated monitoring system. Also hereafter, as this system uses the remote monitoring system through network and constitute the data base(DB), it will play an important role in building the automation of power system efficiently and systematically.

• Mycobiology
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• v.38 no.4
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• pp.282-285
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• 2010

Cordyceps cardinalis successfully produced its fruiting bodies from multi-ascospore isolates. However, subcultures of multiascospore isolates could not produce fruiting bodies after few generations. Fruiting body production also differed from sector to sector of the same isolate. Single ascospore isolates were then co-inoculated in combinations of two to observe the fruiting characteristics. Combinations of certain isolates produced perithecial stromata formation, whereas other combinations did not produce any fruiting bodies. These results show that C. cardinalis is a heterothallic fungus, requiring two isolates of opposite mating types for fruiting body production. It was also shown that single ascospore isolates are hermaphrodites.

• Proceedings of the KIEE Conference
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• 2005.10b
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• pp.50-52
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• 2005

Research interests in PQ(Power Quality) measurement and monitoring system have been increased. This paper describes an experimental result for monitoring system that monitors power quality and undesirable accidents when distributed generations are connected to the power grid. Prior to develop a physical monitoring system for distributed generation applications, we constitute a mesuring system for the general PQ factors. In this paper, an approach to how to measure the PQ elements is presented by using TMS320C6701 processor. Simulation results using the PSCAD and the power system simulation equipment Dobel have verified the proposed measurement system.

• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.101.4-101
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• 2001

Evolutionary algorithm has been receiving a remarkable attention due to the model-free and population-based parallel search attributes and much successful results are coming out. However, there are some problems in most of the evolutionary algorithms. The critical one is that it takes much time or large generations to search the global optimum in case of the objective function with multimodality. Another problem is that it usually cannot search all the local optima because it pays great attention to the search of the global optimum. In addition, if the objective function has several global optima, it may be very difficult to search all the global optima due to the global characteristics of the selection methods. To cope with these problems, at first we propose a preprocessing process, grid-filtering algorithm(GFA), and propose a new distributed evolutionary ...

• International Journal of Human Ecology
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• v.13 no.1
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• pp.89-103
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• 2012

Using a life course framework, we compare and contrast the processes of acculturation for first- and second-generation Korean immigrant fathers in the United States. In-depth life history interviews were conducted with 20 first-generation and 15 second-generation fathers in the Midwest. With a modified grounded theory approach of constant comparison, we first explored how these fathers developed their identities in the midst of cultural and social transitions. These men's identity construction was shaped by socio-economic statuses and accessibility to cultural resources, with a marked shift over time toward integration of Korean and American identities. We then examined how these identities informed the men's socialization of their children, and the children's socialization of their parents.

• Tuberculosis and Respiratory Diseases
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• v.73 no.3
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• pp.169-173
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• 2012

Background: Spontaneous pneumomediastinum is a rare and benign condition that generally occurs in young generations without any precipitating factor or underlying disease. The purpose of this study is to review our experience in dealing with this entity and detail a reasonable course of assessment and management. Methods: From December 1999 to May 2012, 32 spontaneous pneumomediastinum patients were managed in our hospital. We retrospectively reviewed the result of management. Results: Patients ranged in age from 10 to 38 years, with the mean age of $18.3{\pm}5.6$ years. Twenty-five patients were men and seven were women. Initial WBC count was $10,039{\pm}2,993/{\mu}L$ and thirty-one patients underwent computed tomography. Twenty-two patients underwent esophagography and results were shown to be normal. Twenty-five patients were admitted in the hospital and the mean duration of admission was $3.4{\pm}2.0$ days. All patients were managed conservatively and discharged without any complications. Conclusion: Spontaneous pneumomediastinum is a benign condition combined with mild inflammatory signs and secondary causes must to excluded to avoid unfavorable outcomes and select proper management modality.

• Proceedings of the KSPS conference
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• 2007.05a
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• pp.247-250
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• 2007

The affricates of the Korean were alveolar sounds in the 15th century. Alveolar sounds have changed to post-alveolar or alveo-palatal sounds since the 18th century, at least in Southern Korean. These days, the advanced articulation of the affricates are observed, especially in the speech of young generations. The aim of this paper is to show the differences of the affricates when they are pronounced in alveo-palatal and in a more advanced position than in alveo-palatal by their cut-off frequencies. We have recorded speeches of freshmen(in their early twenties) at Seoul National University. The result was that the cut-off frequency of the advanced articulation in auditory observations was higher than that of the others. We have found in particular, that women have tendency to advance their place of articulation of the affricates.