• 한국전자파학회논문지
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• 제20권3호
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• pp.303-312
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• 2009

본 연구에서는 초고주파를 사용하여 플라즈마 가시광을 발생시키기 위한 전계 집속형 도파관 시스템을 제안하였다. 이 시스템은 초고주파 전력 공급기인 마그네트론, 전력 전송을 위한 도파관부 및 메쉬형 공동으로 이루어진 반응기로 구성된다. 소량의 황 분말과 버퍼 가스인 Ar이 봉입된 석영 벌브를 반응기 내에 위치시키고, 강한 전계를 집속시킴으로써 황 플라즈마가 생성 및 여기되도록 하였다. 즉, 도파관과 반응기의 내벽에 각각 도체팁을 장착시키고, 그 사이에 플라즈마 벌브를 위치시킴으로써 벌브에 강한 전계가 집중되도록 하였다. 또한 플라즈마 생성 과도기에서, 플라즈마의 전기적 도전성 변화에 따른 정합 특성의 열화를 최소화할 수 있는 도파관부를 설계하여 안정적으로 동작되도록 하였다. 최종적으로 2.45 GHz 알루미늄 도파관 시스템을 제작하고, 400W급 마그네트론을 사용한 가시광 방출 실험을 통해 설계된 시스템의 타당성을 검증하였다.

• 한국세라믹학회지
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• 제49권6호
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• pp.528-534
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• 2012

In this study, the densification behavior and microstructural evolution of CuO were examined when this material was sintered at different temperatures in $O_2$, air and Ar atmospheres. The CuO samples maintained their phases even after prolonged sintering at $900-1100^{\circ}C$ in an oxygen atmosphere. When sintering in air, the densification was faster than it was when sintering in oxygen. However, when the samples were sintered at $1100^{\circ}C$, large pores were observed in the sample due to the phase transformation from CuO to $Cu_2O$ which accompanies the generation of oxygen gas. The pore channels in the sample became narrower as the sintering time increased, eventually undergoing a Rayleigh breakup and forming discrete isolated pores. On the other hand, CuO sintering in Ar did not contribute to the densification, as all CuO samples underwent a phase transformation to $Cu_2O$ during the heating process.

• 조명전기설비학회논문지
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• 제22권12호
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• pp.142-149
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• 2008

본 논문은 비열평형 플라즈마와 촉매를 이용하여 트리클로로에틸렌의 효과적인 분해방법을 제안하였다. 이를 위하여 이산화망간과 알루미나 펠렛을 플라즈마 리액터 내부에 충진한 리액터를 설계하였다. 이산화망간 충진 리백터를 이용할 경우에는 산소를 포함한 가스중의 방전에 의해 발생된 오존이 촉매 표면에서 분해되는 동안에 발생된 산소원자 라디칼에 의하여 TCE의 분해율이 향상됨을 알 수 있었다. 그리고 알루미나를 충진한 경우에는 TCE DCAC로 산화되었으며, COx 및 $Cl_2$와 같은 저분자상으로 많이 분해되지 않았다. 그러나 알루미나 충진 리액터에 의한 플라즈마 처리된 가스를 리액터 후단에 설치한 이산화망간 촉매를 통과시킴에 의하여 분해율이 매우 향상됨을 알 수 있었다. 따라서, 플라즈마 프로세스에 이산화망간을 응용함에 의하여 오존 분해에 따른 촉매 표면의 산소원자 라디칼에 의하여 TCE 및 분해 생성물(DCAC)를 효율적으로 분해하는 것이 가능하다.

• 환경영향평가
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• 제11권1호
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• pp.25-36
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• 2002

The purpose of this study is to assess the environmental carrying capacity of Chongju City for the environmental management and the urban growth management. The urban environmental carrying capacity assessment of the city by the index of ecological footprint(EF), shows that the ecosystem of the city has been overloaded and most of the deficiencies has come from outside of the city. The EF index, the area of land per capita required for production and consumption in the city, was 1.731 ha per capita in 1989 and 1.901 ha per capita in 1999. On the other side, the ecologically productive land is 0.0175 ha per capita. It means that every citizen owes 1.88 ha per capita to the ecosystem in 1999. The land consumption of the city has increased by 0.1705 ha per capita during the last 10 years. The capacity of infrastructure and the service supply estimated by the Onishi model does not exceed the demand of the city in 1999. But the rapidly increasing population and fast urban growth need the expansion of the capacity. The water supply capacity of the city appears to be sufficient in 1999, but the water supply demand will increase in the future. The capacity of sewage treatment facilities seems to be sufficient, but the higher level of sewage treatment facilities should be adopted for the improvement of water quality as the generation of sewage will increase and its characteristics will also make the wastewater treatment difficult. Due to the decrease of solid waste generated, the land fill capacity for solid waste disposal is not insufficient at present, but the capacity will be saturated in the near future. Therefore, the scientific management system of solid wastes should be introduced. The air quality of the city meets both the national air quality standard and WHO recommendation standard, but the strong regulation and control of automobile emission gas such as CO, $CO_2$, NOx and HC is required for clean air.

• 한국자동차공학회논문집
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• 제14권5호
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• pp.32-38
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• 2006

Currently, due to the serious world-wide air pollution by substances emitted from vehicles, emission control is enforced more firmly and it is expected that the regulation requirements for emission will become more severe. A new concept combustion technology that can reduce the NOx and PM in relation to combustion is urgently required. Due to such social requirement, technologically advanced countries are making efforts to develop an environment-friendly vehicle engine at the nation-wide level in order to respond to the reinforced emission control. As a core combustion technology among new combustion technologies for the next generation engine, the homogenous charge compression ignition(HCCI) is expanding its application range by adopting multiple combustion mode, catalyst, direct fuel injection and partially premixed combustion. This study used a 2-staged injection method in order to apply the HCCI combustion method without significantly altering engine specifications in the aspect of multiple combustion mode and practicality by referring to the results of studies on the HCCI engine. In addition, this study confirmed the possibility of securing optimum fuel economy emission reduction in the IMEP 8bar range(which could not be achieved with existing partially premixed combustion) through forced charging, exhaust gas recirculation(EGR), compression ratio change and application of DOC catalyst.

• 한국자동차공학회논문집
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• 제15권1호
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• pp.162-170
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• 2007

Currently, due to the serious world-wide air pollution by substances emitted from vehicles, emission control is enforced more firmly and it is expected that the regulation requirements for emission will become more severe. Anew concept combustion technology that can reduce the NOx and PM in relation to combustion is urgently required. Due to such social requirement, technologically advanced countries are making efforts to develop an environment-friendly vehicle engine at the nation-wide level in order to respond to the reinforced emission control. As a core combustion technology among new combustion technologies for the next generation engine, the homogeneous charge compression ignition (HCCI) is expanding its application range by adopting multiple combustion mode, catalyst, direct fuel injection and partially premixed combustion. This study used a 2-staged injection method in order to apply the HCCI combustion method without significantly altering engine specifications in the aspect of multiple combustion mode and practicality by referring to the results of studies on the HCCI engine. And it is investigated that the effects of the engine rpm and load(or A/F) to emission characteristics.

• 조명전기설비학회논문지
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• 제19권5호
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• pp.60-67
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• 2005

본 논문에서는 진공방전관을 이용한 고농도 중첩방전형 오존발생기를 설계$\cdot$제작하였다. 3개의 전극(중심전극, 내부전극 및 외부전극)과 1개의 방전간극(내부전극과 외부전극 사이의 방전간극)으로 구성된 중첩방전형 오존발생기는 진공방전관내에 장착한 중심전극과 내부전극에 $180{[^\circ]}$의 위상차를 가진 2개의 교류고전압을 인가하고 외부전극을 공통접지함으로써 중심전극과 외부전극사이에서 발생되는 무성방전과 내부전극과 외부전극사이에서 발생되는 무성방전이 방전간극에서 중첩되는 구조이다. 이때 방전관의 진공도, 방전전력 및 산소원료가스 유량 변화에 따른 방전특성과 오존생성특성을 연구검토한 결과 최대 8840[ppm]의 고농도 오존을 얻을 수 있었다.

• 전기학회논문지P
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• 제65권3호
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• pp.165-170
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• 2016

Due to environmental issues such as global warming, the reduction of greenhouse gas emissions has become an inevitable measure to be taken. Among others, the building sector accounts for 50% of total carbon dioxide emissions, which is significantly high. Therefore, in order to reduce carbon dioxide emissions of the buildings, improving the energy efficiency by utilizing wind power among renewable energy sources is recommended. In case of buildings in the planning stage, it is possible to take the load of wind power generation systems into consideration when determining installed capacity. Already completed buildings, however, should be connected to small wind electric systems according to the live loads of the buildings based on the architectural design criteria. In order to connect to a building that has already been completed, it is necessary to consider the load of the small wind electric system as well as the live load of building. In addition, we need to generate the maximum electricity possible by determining the maximum installed capacity in a small area. In this paper, we propose the method for determining maximum capacity for building integrated small wind electric systems, which takes into account the considerations associated with connecting small wind electric systems to completed buildings. This can be developed into a system linked to solar power, which makes it possible to improve the energy independence of the building. In addition, carbon dioxide reduction by improving energy efficiency is expected.

• 한국전기전자재료학회논문지
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• 제23권7호
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• pp.534-538
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• 2010

X-ray systems for medical treatment use noninvasive procedures. Being capable of locally inspecting the inside of the body, X-ray systems are routinely used for basic diagnosis. X-ray systems to be used for medical purposes were originally made with a gas filled tube inside an induction coil in the initial stages of development but with this approach it becomes difficult to take a satisfactory picture through thick body sections, non invasively. However continued development made it possible to take non-invasive pictures of breasts, blood vessels and other body parts through thick body sections. Recently, high-voltage X-ray generators of more compact size, increased generation efficiency, and sophisticated output control have become possible. All of these features are made possible by the use of a high-frequency output from an inverter and a fast switching semiconductor device. In this paper, we describe a new X-ray generator operating with a resonant inverter in order to reduce switching loss and high frequency noise. In addition, in order to identify the differences amongst types of rectification, we have compared output and the quality of X-ray pictures obtained with full-wave rectification and dual-voltage rectification methods.

• Nuclear Engineering and Technology
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• 제48권2호
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• pp.457-469
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• 2016

During the late phase of severe accidents of light water reactors, a porous debris bed is expected to develop on the bottom of the flooded reactor cavity after breakup of the melt in water. The geometrical configuration, i.e., internal and external characteristics, of the debris bed is significant for the adequate assessment of the coolability of the relocated corium. The internal structure of a debris bed was investigated experimentally using the DAVINCI (Debris bed research Apparatus for Validation of the bubble-Induced Natural Convection effect Issue) test facility. Particle sedimentation under the influence of a two-phase natural convection flow due to the decay heat in the debris bed was simulated by dropping various sizes of particles into a water vessel with air bubble injection from the bottom. Settled particles were collected and sieved to obtain the particle mass, size distribution in the radial and axial positions, and the bed porosity and permeability. The experimental results showed that the center part of the particle bed tended to have larger particles than the peripheral area. For the axial distribution, the lower layer had a higher fraction of larger particles. As the sedimentation progressed, the size distribution in the upper layers can shift to larger sizes because of the higher vapor generation rate and stronger flow intensity.