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탄소섬유강화복합재료(CFRP) 레저선박의 횡요저항력 평가에 의한 상부구조물 풍압면적 특성
김도윤,이창우,이동건,오대균,Kim, Do-Yun,Lee, Chang-Woo,Lee, Dong-Kun,Oh, Dae-Kyun 해양환경안전학회 2014 해양환경안전학회지 Vol.20 No.6
일반적으로 CFRP 레저선박의 상부구조물은 동급전장 타 선박보다 매우 작은 경향을 보이고 있는데, 이는 풍압면적에 의한 횡요저항력과 밀접한 관련이 있는 것으로 알려져 있다. 본 연구에서는 CFRP 레저선박의 이러한 상부구조물 형상 특성을 풍압면적 변화에 따른 복원안정성 분석을 통해 파악하고자 한다. GFRP 레저선박과 CFRP 레저선박의 선체 및 상부구조물 형상 특성을 상호 비교하고, CFRP 레저선박의 상부구조물 형상변화를 통해 그 변화가 복원안정성에 미치는 영향에 대해 분석하였다. 이를 위해 GFRP, CFRP 레저선박 총 10척의 형상을 비교, 분석하여 선체와 상부구조물 간의 형상 추세를 파악하였고, ISO 12217에 따른 횡요저항력 추정 및 복원안정성 평가 프로그램 개발을 통해 상부구조물의 형상 변화와 복원안정성 간의 관계를 분석하였다. 연구결과, CFRP 레저선박의 풍압면적 분포경향은 GFRP 레저선박과 비슷하였으나, 상대적으로 상부구조물 형상 비율은 절반정도 크기에 그치는 경향을 보였다. 또한 CFRP 레저선박의 상부구조물 크기를 동급전장의 GFRP 선박 상부구조물 면적 비율 이상(10%) 증가시키는 경우 횡요저항력에 의한 복원성능에 문제가 발생하는 것을 확인할 수 있었다. This research aims to investigate the superstructure characteristics of the CFRP-yachts whose hulls are made of the light-weight material CFRP. CFRP-yachts, which belong to light-weight yachts, have a tendency of having very small superstructures compared to other vessels of the same length, and such a tendency is closely related to stability. In this research, a comparison of shape characteristics was made between common composite-plastic yachts and CFRP-yachts to find out the shape characteristics of CFRP-yacht. In the meantime, a case study was conducted concerning shape changes in superstructure to understand the effect of such changes on stability. For this purpose the shapes of a total of 10 GFRP-yachts and CFRP-yachts were comparatively analyzed, and the result showed the tendency of their hulls and superstructures. Whereas the case study on stability assessment involved various superstructure shapes of CFRP yachts, for assessment by superstructure size. Stability assessment was according to ISO 12217 (Small craft Stability and buoyancy assessment and categorization). A program was also developed based on stability assessment process due to rolling in beam waves and wind, and it was applied to the case study. The result of the case study showed that the windage area distribution tendency of the yachts whose hulls were made of the light-weight material CFRP was similar to that of the GFRP-yachts, but that the superstructure shapes of the CFRP-yachts were about 50% smaller than those of the GFRP-yachts. In addition, the stability assessment involving various superstructure areas of the CFRP-yachts showed that problems with stability occurred when their superstructure sizes were similar to, or larger by about 10% than, those of the GFRP-yachts.
가변 노치필터에 의한 능동형 AC 전자부하의 3상 전류 불평형 저감
김도윤(Do-Yun Kim),이정효(Jung-Hyo Lee),이용석(Yong-Seok Lee),정두용(Doo-Yong Jung),정용채(Yong-Chae Jung),원충연(Chung-Yuen Won) 전력전자학회 2012 전력전자학회 논문지 Vol.17 No.2
In this paper, the test bed using three-phase PWM converter connected with single phase inverter in series is set up to configure an active AC electric load. Since the two topologies, three-phase PWM converter and single-phase inverter, can be operated bidirectionally, the system not only re-generates surplus power to grid but also prevents power dissipation. However, the construction of system has a drawback. That is, ripple components two times of inverter operation frequency occur at DC-Link due to cascade connection, it can be cause of three phase unbalance Since the operational characteristic of the active AC electric load, the power frequency entered into the electric load can be varied, and the ripple of DC-Link is changed as well. In this paper, the three-phase PWM converter using a variable notch filter is proposed, and the reduction of three-phase current unbalance is presented. the validity of the proposed PWM converter using a variable notch filter is verified by the simulation and experimental results.
김도윤(Doyun Kim),박은성(Eunsung Park),이성민(Sungmin Lee),성동수(Dongsu Seong),이건배(Keonbae Lee) 대한전기학회 2009 정보 및 제어 심포지엄 논문집 Vol.2009 No.5
VoIP(Voice over IP) is the technology to transport voice and video over IP networks such as Internet. Today, VoIP technology is viewed as the right choice for provide voice, video, and data communication over next generation network. We are sure that the multipoint VoIF will help enhancing the various application services in ubiquitous environment. The paper shows multipoint VoIP system implemented with end-point mixing model and introduces various embedded systems such as UFC(Ubiquitous Fashionable Computer), tourist guide terminal and industrial terminal which use the multipoint VoIP.
이지섭,김도윤,이창준,이정훈,한승헌,Lee, Jiseop,Kim, Doyun,Lee, Changjun,Lee, Jeonghun,Han, Seungheon 한국건설관리학회 2018 건설관리 : 한국건설관리학회 학회지 Vol.19 No.2
Conflicts in public construction projects lead to increase social costs as well as construction costs and schedule delay. Therefore, it is important to evaluate the conflict in construction project and find appropriate solutions based on previous cases. In this research, the conflict factors and criteria for evaluating conflict are derived and 30 cases are evaluated by 11 conflict experts. Using k-means clustering, the cases are clustered by three clusters. The cases were analyzed according to the characteristics of each cluster and labeled as 'NIMBY and harmful facility conflict cluster', 'environmental and pollution conflict cluster', and 'PIMFY and small conflicts'. In the future, when conflict occurs in the public construction projects, the conflict can be evaluated using this clustering and the characteristics of the conflicts can be found. As a result, it will be helpful to mitigate the conflict quickly and effectively by looking for previous cases that are suitable for resolving the conflict through appropriate clusters. 공공 건설사업에서 발생하는 갈등은 공사비 증가, 공기 지연뿐만 아니라 사회적 비용의 낭비를 초래하며 성공적이지 못한 사업으로 이어진다. 따라서 갈등의 유형을 진단하여 선행사례를 통해 적절한 해결방안을 모색하는 것이 중요하다. 본 연구에서는 국내외 많은 문헌들을 고찰하여 갈등의 원인이 되는 갈등 요인을 도출하고 평가할 수 있도록 평가 기준을 수립하여 갈등을 유형화하였다. 30개의 사례에 대해 갈등 요인을 평가를 받고 군집분석을 통해 유사한 사례들을 군집화 하였다. 3개의 군집으로 구성되었으며, 각 군집의 특성에 따라 사례를 분석하여 '유해성 및 님비 시설물 갈등 군집', '환경 및 공해 갈등 군집', '핌피 및 소형 갈등'이라고 명명하였다. 추후 공공 건설사업에서 갈등 발생 시 본 유형화 기준에 따라 갈등을 평가하고 어떤 유형의 갈등인지 파악한 후 해당 군집의 선행 사례를 통한 효과적인 선행사례를 모색하여 빠르고 효과적인 갈등 해결에 도움이 되고자 한다.
한국형 지역 위성 통신항법시스템의 위성 궤도설계에 관한 연구
이상현(Sanghyun Lee),박병운(Byungwoon Park),김도윤(Doyoon Kim),기창돈(Changdon Kee),백복수(Boksoo Paik),이기훈(Kihoon Lee) 한국항공우주학회 2005 韓國航空宇宙學會誌 Vol.33 No.7
군사용 목적으로 만들어진 GPS가 1990년대에 민간에 개방됨에 따라 차량 항법, 항공기, 통신, 과학, 농업, 탐사 등에 이르는 산업에 폭넓게 이용되고 있다. 하지만, GPS는 미국이 독점적으로 운영하고 있기 때문에 세계 각국은 안보문제에 우려를 나타내고 있는 실정이다. 또한 우리나라와 같이 산악 지형 및 도심이 발달한 지역은 GPS 단독 사용 시에 여러 가지 제약점을 가진다. 이러한 점들을 해결하기 위해 주위의 여러 나라들은 새로운 항법 체계를 구상 중에 있다. 이러한 국제적 추세에 대비하여 우리나라도 지역 항법 시스템 구축에 대해서 검토가 필요하다고 판단된다. 본 논문에서는 우리나라 지역 특성을 고려하여 고앙각의 통신서비스를 제공하며, 독자적 항법 능력을 가진 지역 위성 항법시스템의 위성 궤도를 여러 가지 고려사항을 구속조건으로 하여 설계하였다. 최종 설계된 위성항법시스템의 독자 항법 성능뿐만 아니라 부가적으로 GPS를 보강하는 성능도 우수함을 확인하였다. In 1990, GPS which had been developed for the military purposes became available to the civilian community. Since then these satellite navigation systems have been used extensively in the industrial areas such as car navigation, airplanes, communications, science and surveying. If we are dependent on GPS, however, there are some foreseeable problems in the areas of national security and sovereignty. Current GPS satellite constellation provides limited performance for the country like Korea and Japan where mountain area and urban canyon do not allow the wide skyline. To solve these problems, many countries plan to make other alternative navigation systems. In this paper, RNSS(Regional Navigation Satellite System) is designed to provide communication service with high elevation angle. It is shown, that system does not only have good navigation performance, but also improve GPS performance in Korea and its neighboring areas.
VUV 이오나이저용 Ca-Sr-Ba계 산화물 캐소드에 낮은 일함수를 갖는 금속산화물 첨가의 영향
박승규,이종혁,김란희,정주형,한완규,이수현,전성우,김대준,김도윤,이광섭,Park, Seung-Kyu,Lee, Jonghyuk,Kim, Ran Hee,Jung, Juhyoung,Han, Wan Gyu,Lee, Soo Huan,Jeon, Sung Woo,Kim, Dae Jun,Kim, Do-Yun,Lee, Kwang-Sup 한국재료학회 2019 한국재료학회지 Vol.29 No.4
There are several manufacturing techniques for developing thermionic cathodes for vacuum ultraviolet(VUV) ionizers. The triple alkaline earth metal emitters(Ca-Sr-Ba) are formulated as efficient and reliable thermo-electron sources with a great many different compositions for the ionizing devices. We prepare two basic suspensions with different compositions: calcium, strontium and barium. After evaluating the electron-emitting performance for europium, gadolinium, and yttrium-based cathodes mixed with these suspensions, we selected the yttrium for its better performance. Next, another transition metal indium and a lanthanide metal neodymium salt is introduced to two base emitters. These final composite metal emitters are coated on the tungsten filament and then activated to the oxide cathodes by an intentionally programmed calcination process under an ultra-high vacuum(${\sim}10^{-6}torr$). The performance of electron emission of the cathodes is characterized by their anode currents with respect to the addition of each element, In and Nd, and their concentration of cathodes. Compared to both the base cathodes, the electron emission performance of the cathodes containing indium and neodymium decreases. The anode current of the Nd cathode is more markedly degraded than that with In.