• Proceedings of the KIEE Conference
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• 1994.07b
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• pp.1612-1614
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• 1994

Modulators Installed in PLS(Pohang Light Source) Linac are composed of a DC high voltage section, a charging section and a discharging section. PFN is charged by a resonant charging mechanism, and discharged by a switching device through the primary of the pulse transformer connected to a load. Charged PFN voltage must be well regulated to obtain stable output pulse voltage at the load. For this purpose, DCHV is controlled by a SCR controller with feedback signal, and PFN voltage is regulated by a De-Q'ing circuit. The full power operation test shows the pulse voltage regulation within ${\pm}0.13%$ with SCR feedback control alone, and within ${\pm}0.08%$ together with De-Q'ing. This paper describes the design concept and operational characteristics of the De-Q'ing circuit.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.44 no.3
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• pp.39-44
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• 2007

In this paper, satellite searching and tracking method for the satellite antenna in naval vessels system are proposed. For fast searching satellite, Wide Range Search(WRS) algorithm is proposed where the signal strength of side-lobe is utilized as well as that of main-lobe. Satellite tracking algorithm to stabilize satellite antenna is based on conical-scanning which is accomplished by the use of the sub-reflector located in front of the focus of the reflector. The sub-reflector rotates about a slightly tilted axis by means of a motor and shapes the antenna beam to utilize stabilization. To show the validity of the proposed method, an experimental example is represented.

• Journal of the Korean Institute of Telematics and Electronics S
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• v.35S no.4
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• pp.67-75
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• 1998

In general, Evoluationary Algorithm(EAs) are refered to as methods of population-based optimization. And EAs are considered as very efficient methods of optimal sytem design because they can provice much opportunity for obtaining the global optimal solution. This paper presents a co-evolution scheme of artifical neural networks, which has two different, still cooperatively working, populations, called as a host popuation and a parasite population, respectively. Using the conventional generatic algorithm the host population is evolved in the given environment, and the parastie population composed of schemata is evolved to find useful schema for the host population. the structure of artificial neural network is a diagonal recurrent neural netork which has self-feedback loops only in its hidden nodes. To find optimal neural networks we should take into account the structure of the neural network as well as the adaptive parameters, weight of neurons. So we use the genetic algorithm that searches the structure of the neural network by the co-evolution mechanism, and for the weights learning we adopted the evolutionary stategies. As a results of co-evolution we will find the optimal structure of the neural network in a short time with a small population. The validity and effectiveness of the proposed method are inspected by applying it to the stabilization and position control of the invered-pendulum system. And we will show that the result of co-evolution is better than that of the conventioal genetic algorithm.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.5 no.3
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• pp.226-233
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• 1993

Thermosyphons are simple devices that can passively transport thermal energy over relatively large distance with little temperature degradation. Especially, the thermosyphon system requires no costly energy input and is completely maintenance free. These attributes permit the use of low grade thermal energy for thermal control of structures including the stabilization of highway foundations. This paper presents the experimental results of the snow melting system in which thermosyphon was utilized to ransfer the earth energy to the pavement to remove snow and ice. The test facility, three earth heated and one unheated test panels, is designed to investigate the variables associated with removing snow and ice from pavement surfaces. The results of these test show that the earth heated panel surface temperature is higher $2{\sim}6^{\circ}C$ than unheated panel when the ambient air temperature is $-7^{\circ}C$. The thermal performance of this earth source thermosyphon system for road heating showed that there was no snow on the heated test panels when the snowfall was 5cm average for the region.

• Proceedings of the SCSK Conference
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• 2003.09b
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• pp.464-478
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• 2003

Free radicals and reactive oxygen species (ROS) caused by UV exposure or other environmental facts play critical roles in cellular damage and aging. The extract of tinged autumnal leaves of maple tree(Acer palmatum) has proven to be a powerful antioxidant. The Acer palmatum extract is very effective on the stabilization of biological membranes( containing unsaturated fatty acid). We studied photoprotective effect of the extract against UVB-induced cytotoxicity in human keratinocytes. The extract improved cell viability comparing to control after UVB irradiation. In the determination test of pro inflammatory cytokines the extract decreased expression of interleukin 1 a and 6, which play an important role in inflammation and skin erythema caused by UV. We also studied property of varying cosmetic formulations on the percutaneous absorption of the extract. After 24 hour in vitro penetration study, the content of the extract was more highly detected in skin residue part. This result showed the extract had relatively high compatibility of skin in our emulsion system. On human skin, after appling the product containing the extract we obtained a good result of antiwrinkle effect by skin visiometer. In conclusion, the Acer palmatum extract is a photoprotective and very effective in stressed and aged skin care. And we can predict the extract mainly affects on the skin cell and tissue in our emulsion system.

• Journal of Wetlands Research
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• v.7 no.3
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• pp.33-39
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• 2005

Constructed wetlands are considered as an important tool for wastewater treatment, wastewater management and flooding control. In addition, one of the most promising technologies for application in many countries seems to be constructed wetlands due to their properties such as utilization of natural processes, simple construction, operation and maintenance, process stability, cost effectiveness, etc. This research is performed to find the possibility for treating livestock wastewater using a constructed wetland. The removal efficiencies of CODcr, TN, TP, SS, and color were 97.9%, 97.8%, 97.2%, 99.1%, and 84.9%, respectively. In particular, SS was completely removed. In conclusion, constructed wetlands could be applied to livestock wastewater treatment. Further, it needs time for stabilization to reduce the pollutants accumulated in soil.

• Journal of the Korean Institute of Intelligent Systems
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• v.16 no.2
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• pp.209-214
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• 2006

The eccentricity of the rotor causes a rotary machine to unbalance and the balancing to correct or compensate this is very important not only for dust-proof and anti -noise design but also for stabilization and durability of the rotary machine. In this paper, for developing the balancing machine to find and compensate such eccentricity, we will propose new way of measuring eccentricity using hall effect sensor that is different from the way in a conventional balancing machine. And we will show that it is possible to make balancing machine more compactly and cheaply by experiment results using hall effect sensor to measure eccentricity. Moreover we try to control and monitor the balancing machine by personal computer through serial communication.

• Environmental Analysis Health and Toxicology
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• v.23 no.4
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• pp.307-314
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• 2008

폐기물 매립지의 조기 안전화를 위해 여러 가지 Chemical Oxidation법이 개발되어 왔지만, 이 방법을 폐기물 매립지에 적용하고 난 후에 생성될 수 있는 부산물들이 주변 환경에 영향을 줄 가능성이 있다. 그래서, 이 방법을 실제 매립지에 적용하기 전에, 일본 키타큐슈에 있는 소각재가 묻혀 있는 모형 매립지에 다섯 가지 조건 -A, 콤포스트 추가; B, 과산화수소수 살수; 과산화수소수+공기주입; D, 공기주입; E, control- 을 적용하여 그 효능을 테스트하였고, 이 매립지에서 이 방법들의 적용 후에 생성되는 침출수의 급성 독성을 세 가지 microbiotests를 이용하여 monitoring하였다. 테스트 기간 중, 침출수의 수질은 개선되었고, 그 급성 독성은 점차적으로 감소하였다. 과산화수소수와 공기의 조합을 적용한 후 생성된 침출수의 급성 독성이 가장 빨리 감소하여 폐기물 매립지의 조기 안정화에 도움을 주었다. 이러한 독성 시험 결과는 몇 가지 화학적 parameters와 상관성이 있었고 여기에 사용된 급성 독성 테스트법은, 매립지 안정화를 위한 Chemical Oxidation법의 적용 후, 침출수 수질을 monitoring하는데 적절하였다. 그러므로 폐기물 매립지의 조기 폐지 기준에 독성 시험의 포함을 고려해 볼 필요가 있다고 생각한다.

• Environmental Engineering Research
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• v.19 no.3
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• pp.185-195
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• 2014

Despite the enormous technical and economic efforts to improve environmental conditions, currently about 40% of the global population (or 2 billion people) are still lack access to safe water supply and adequate sanitation facilities. Pollution problems and transmission of water- related diseases will continue to proliferate. The rapid population growth and industrialization will lead to a reduction of arable land, thus exacerbating the food shortage problems and threatening environmental sustainability. Natural systems in this context are a transdisciplinary approach which employs the activities of microbes, soil and/or plants in waste stabilisation and resource recovery without the aid of mechanical or energy-intensive equipments. Examples of these natural systems are: waste stabilisation ponds, aquatic weed ponds, constructed wetlands and land treatment processes. Although they require relatively large land areas, the natural systems could achieve a high degree of waste stabilisation and at the same time, yield potentials for waste recycling through the production of algal protein, fish, crops, and plant biomass. Because of the complex interactions occurring in the natural systems, the existing design procedures are based mainly on empirical or field experience approaches. An integrated kinetic model encompassing the activities of both suspended and biofilm bacteria and some important engineering parameters has been developed which could predict the organic matter degradation in the natural systems satisfactorily.

• Environmental Engineering Research
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• v.13 no.3
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• pp.112-118
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• 2008

Residual solid in excess sludge treated by hydrothermal reaction was investigated as raw material for its recycling. Treated excess sludge and residual solid were also focused on their content change during hydrothermal reaction. Two kinds of excess sludge, obtained from a local food factory and a municipal wastewater treatment process, were tested under various conditions. Following hydrothermal reaction, depending on the reaction conditions, biodegradable substrates in treated excess sludge appeared to increase. The separated residual solid was a composite composed of organic and inorganic materials. The proportion of carbon varied from 34.0 to 41.6% depending on reaction conditions. Although 1.89% of hazardous materials were detected, SiO2 (Quartz) was a predominant constituent of the residual solid. X-ray diffraction (XRD) experiments revealed that the residual solid was of a partially amorphous state, suggesting that the residual solids could be easily converted to stable and non harmful substances through a stabilization process. Thus, this technology could be successfully used to control excess sludge and its reuse.