• 전기학회논문지
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• 제66권7호
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• pp.1032-1038
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• 2017

Recently, regulation on carbon emissions has been strengthened according to the new climate change convention (COP21) held in Paris, and then Korea has decided to reduce CO2 emissions by 37% until 2030. As one of countermeasures, the government has energetically performed demonstration projects of island micro-grid including solar power, wind power and energy storage system. However, in order to smoothly introduce island micro-grid, it is a critical issue to carry out the economic evaluation for power utility aspect and independent power producer aspect. Therefore, this paper proposes economic evaluation algorithms of island micro-grid which are based on the present worth method, considering cost and benefit factors in the aspect of both sides. Firstly, in case of power utility this paper proposes algorithm to estimate a period of return on investment according to the introduction capacity of distributed generators replacing diesel generator. And also, in case of independent power producer, this paper proposes evaluation algorithm to estimate weighting factor of SMP and benefit rate based on break-even point related with cost and benefit. From a case study result on real island micro-grid model, it is confirmed that proposed algorithms are useful and practical for the economic evaluation of island micro-grid.

• 조명전기설비학회논문지
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• 제22권12호
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• pp.29-35
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• 2008

본 논문에서는 부하전류의 급격한 변화에도 안정적인 출력진압을 얻기 위하여 강압쵸퍼의 전압제어 기를 개선하는 방법으로 부하전류 전향보상기를 제시하였다. 제시된 부하전류 전향보상기의 특성을 확인하기 위해 메이슨(Mason)의 이득공식을 이용하여 기존의 전압제어기가 포함된 전체 시스템의 전달함수와 부하전류 전향보상기가 추가된 전체 시스템의 전달함수를 각각 근궤적선도와 보드선도 상에서 비교하였다. 그 결과 시스템의 극점이 개선되고, 공진주파수에서의 첨두값의 크기 및 절점주파수의 위상여유가 양호한 것을 확인하였다. 따라서, 제시된 제어기법이 강압쵸퍼의 정상상태 및 동특성을 향상시키고 출력에 나타나는 외란에 의한 영향을 감소시킨 것을 확인할 수 있었다.

• 한국정보통신학회논문지
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• 제19권1호
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• pp.127-135
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• 2015

본 연구에서는 DIBR(Depth-Image-Based Rendering) 기법을 사용한 다시점 중간 영상 생성을 하는데 있어서 최종 중간 영상의 화질을 개선하기 위한 방법으로 깊이 정보의 확장과 메쉬 구성 (즉, 표면 재구성) 그리고 이 방법들을 교차 적용하여 어떤 것이 가장 좋은 결과를 낼 수 있는 지에 대해서 실험하였다. 마이크로소프트사에서 제공하는 브레이크 댄서와 발레 영상을 사용하여 실험 결과를 살펴보았고 다양한 틈새 영역 채움 알고리즘을 적용시켜 분석해 보았다. 실험 결과는 기존의 점 구름만을 활용하는 것보다 깊이 정보를 확장하는 방법과 메쉬 구성 방법을 모두 시켰을 때 가장 좋은 결과가 나타났다. 그리고 틈새 영역 채움 알고리즘을 적용하기 전에는 깊이 확장만으로도 충분히 화질이 향상됨을 확인할 수 있었다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2003년도 추계학술대회 논문집 Vol.16
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• pp.200-203
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• 2003

A study on the arc resistance and light reflectance of PTFE (polytetrafluoroethylene) nozzle for circuit breaker is presented. PTFE has been used widely as a material for circuit breaker nozzle. PTFE has excellent electrical resistivity, high melt viscosity, chemical inertness, heat resistance and low loss factor. PTFE melts at $327\;^{\circ}C$ but the viscosity is very high above the melting point. In the arcing environment in a circuit breaker, the fraction of the power is emitted out of the arc and reaches the nozzle wall by radiation, causing ablation at the surface and in the depth of the wall. Some fraction of the radiation power emitted out of the arc directly break up the chemical bonds at the surface while some fraction of the radiation power penetrates into the wall, heats up the material to evaporation temperature and causes damages deeper inside the volume of the nozzle. In this paper, some fillers that have endurance in the high temperature arc environment were added into PTFE. Adding some fillers into PTFE was expected to be efficient in improving the endurability against radiation. The light reflectance and arc resistance of PTFE composites were investigated.

• 폴리머
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• 제26권5호
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• pp.661-669
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• 2002

본 연구는 이온교환 부직포를 이용하여 대기중의 아황산 가스를 흡착제거 시키기 인하여 가스의 농도는 100~200 ppm, 유속을 0.6~l.0 m/sec, 습도를 30~90 RH%로 하여 SO$_2$의 흡착량을 측정하여 음이온교환 섬유 스크러버의 최적조건을 도출하였다. 이온교환체의 이온교환 용량은 pH=4에서 최대 3.75 meq/9이였으며 또한 유속이 0.5 m/s일 때 흡착평형시간이 30시간으로 최대를 나타냈으며, 온도가 8$0^{\circ}C$일 때 흡착평형시간이 최대 10시간이상 짧아지는 경향을 나타냈다. 농도가 200 ppm의 경우 이온교환 섬유의 리간드와 SO$_2$와의 반응속도가 빨라져 흡착 파과가 빨라지는 경향을 나타냈으며 또한 스크러버 내의 상대습도가 90%일 때 7.6%/h의 제거율을 보였는데 이는 상대습도가 30%일 때 4.6%/h보다 30%정도 높은 제거율을 나타내었으며 또한 5 wt% NaOH 용액으로 5분 이내에 완전 탈착이 되었다.

• 한국물환경학회지
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• 제22권3호
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• pp.444-450
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• 2006

This study was carried out to compare the performance of two types of sequencing batch biofilm reactors (SBBRs), anoxic-oxic-anoxic-oxic $(AO)_2$ SBBR and anoxic-oxic-anoxic $A_2O$ SBBR, on the biological nutrient removal. The TOC removal efficiency in $A_2O$ SBBR was higher than that in $(AO)_2$ SBBR. At the 1st non-aeration period, the release of ${PO_4}^{3-}-P$ in $A_2O$ SBBR was higher than that in $(AO)_2$ SBBR because of the high TOC removal. At the 1st aeration-period, the nitrification was not completed in $(AO)_2$ SBBR, however, it was completed in $A_2O$ SBBR and the nitrification rate in $A_2O$ SBBR was higher than that in $(AO)_2$ SBBR. The release and uptake of ${PO_4}^{3-}-P$ in $A_2O$ SBBR was much higher than in $(AO)_2$ SBBR. Also, the profiles of DO and pH in reactors were used to monitor the biological nutrient removal in two SBBRs. The break point in DO and pH curves at the aeration period coincided with the end of nitrification.

• 폴리머
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• 제38권1호
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• pp.9-15
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• 2014

Methylene diphenyl diisocyanate(MDI)와 poly(tetramethylene glycol)(PTMG)로부터 양말단에 isocyanate(NCO) 작용기를 가진 polyurethane(PU) prepolymer를 제조한 다음 이를 개시제로 하고 potassium pyrrolidonate를 촉매로 하여 2-pyrrolidone을 음이온 개환중합함으로써 최종적으로 양 끝에 polyamide4(PA4)가 단단한 블록이 되고 PU가 부드러운 블록이 되는 PA4-PU-PA4 형태의 삼블록 공중합체를 합성하였다. 그리고 공중합체내 각각 PA4 블록과 PU 블록의 분자량을 변화시켜 이들의 변화가 여러 가지 성질에 미치는 영향을 확인하였다. 결과적으로 PA4 블록으로 인해 원래의 PU 탄성체보다 용융온도($T_m$)는 크게 상승하였고 PA4 블록의 분자량이 증가함에 따라 초기 탄성률과 인장강도는 크게 증가하였다. 한편, PU 블록의 분자량이 증가되면 파단신율이 증가하였지만 초기 탄성률과 인장강도는 감소하는 전형적인 블록 공중합체형 탄성체의 성질을 나타냈다.

• 산업경영시스템학회지
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• 제44권3호
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• pp.39-49
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• 2021

The Korean Air-Force aircraft maintenance depot paints the exterior of various aircraft, including high-tech fighters. Aircraft exterior painting is a maintenance process for long-term life management by preventing damage to the aircraft surface due to corrosion. The de-painting process is essential to ensure the quality of aircraft exterior paints. However, because the Korean Air-Force's de-painting process is currently done with sanding or Plastic Media Blasting (PMB) method, it is exposed to harmful dust and harmful compounds and consumes a lot of manpower. This study compares the de-painting process currently applied by the ROK Air-Force and the more improved process of the US Air Force, and performs economic analysis for the introduction of advanced equipment. It aims to provide information that can determine the optimal time to introduce new facilities through Cost-Volume-Profit (CVP) analysis. As a result of the analysis, it was confirmed that the sanding method had the most economical efficiency up to 2 units per year, the PMB method from 3 to 21 units, and the laser method from 22 units or more. In addition, in a situation where the amount of de-painting work is expected to increase significantly due to the increase in fighters in future, BEP analysis was conducted on the expansion of the existing PMB method and the introduction of a new laser method. As a result of the analysis, it was confirmed that it is more economical to introduce the laser method when the amount of work exceeds the PMB work capacity(18 units per year). The paper would helpful to improve the productivity and quality of the Korean Air Force Aircraft maintenance depot through timely changes of facilities in the workplace in preparation for expansion.

• 비교문화연구
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• 제25권
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• pp.291-312
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• 2011

The academic world in Korea demands internationally competitive researches at the moment. However, there is a lack of understanding on research trends of Western countries. This research aims to understand how discussions on early modern Japanese plays are developed in Western countries such as America. Also, it aims to consider and compare the present situation of researches on early modern Japanese plays in Western countries, Japan and Korea. In Western countries, modern Japanese plays such as Kabuki and Joruri is accepted and enjoyed as universal plays of the world. It is not only because there is a background of enjoying plays such as Shakespeare's but also researches and translations are accumulated continuously from the early 20th century. In the early 20th century, the main theme of researches was about Kabuki actors in Ukiyoe which was collected because of an interest in orientalism. After 1930s, Japanese arts and handcrafts were sent to art museums in America in order to promote Japanese culture. Also, many Japanese books were donated to university libraries in order to form institutes of Japanology. The war was started when the foundation of Japanology was about to be laid. Students who were interested in Japan were mobilized to the war as agents to understand Japan. After the war, those students started to do researches on Japan on a full scale. There were researchers such as Donald Keen who did researches on Kabuki and Joruri. In western countries, there are researches on patterns of behavior and thoughts of Japanese people, comparison with Shakespeare's plays, dramaturgie, theatricalism as well as censorship of Kabuki during the war and mobilization of Kabuki to the war. It is necessary to understand where my researches are positioned in those research trends. It is also necessary to break away from overlapped and repeated researches of the same point of view and find out new research paradigms.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2014년도 추계학술대회
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• pp.822-823
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• 2014

다시점 디스플레이용 영상은 주로 레퍼런스가 되는 컬러 카메라와 깊이 카메라의 영상을 입력 받아 DIBR (Depth Image Based Rendering) 기법을 활용, 3차원 점 구름 형태로 재구성 한 후 가상 카메라를 여러 시점에서 배치하여 중간 영상을 생성하여 조합하였다. 이렇게 다시점 중간 영상을 생성하면 원래의 시점에서는 구멍이 없었지만 다른 시점에서는 구멍(Hole)이 보이는 현상이 발생한다. 기존에는 틈새 영역을 채우는 알고리즘을 개발하거나 깊이 영상을 보정하여 개선시키는 방법을 연구하였으나 본 논문에서는 점 구름을 메시(Mesh)화 시키는 알고리즘 중 한 가지인 볼 피봇팅(Ball Pivoting) 방법을 적용시켜 중간 영상의 화질 개선 방법을 설명하고 있다. 마이크로소프트사의 발레와 브레이크 댄서 영상에 개발된 개선 방법을 적용시켜 보았고 PSNR로 비교할 때 약 0.18~1.19정도의 향상을 보임을 확인하였다. 본 논문을 통해 개선 방법과 실험방법, 그리고 결과에 대해 설명한다.