• The Transactions of the Korean Institute of Electrical Engineers B
• /
• v.53 no.1
• /
• pp.1-7
• /
• 2004

This paper presents a sensorless control strategy of a PMSM(Permanent Magnet Sycchoronous Motor). This method is very simple to compute the position angle of a rotor. A principle and a practical solution are described. A sensorless control algorithm is proposed to remove a mechanical position sensor. The theory is based on the superposition principle. The state equation of a motor is divided into two conditions: one is the state equation of exciting voltage and phase current in a constraint, the other is the state equation of back EMF(Electromotive Force) and phase current in a short circuit. Based on the analysis, short circuit current by back EMF is computed and then the information of position angle is calculated. The proposed method is verified by experimental results.

• 전기의세계
• /
• v.10
• /
• pp.55-61
• /
• 1963

본 논문에서 취급한 제동권선이 없는 철극선의 3상단락현상을 해명하는데 있어 우선 임의력율의 전류를 횡축분과 직축분으로 분리해서 취급하는 소위 Blonde의 2반작용법(two reaction method)를 썼고, 각종 Reactance를 표시하는데는 편리한 단위법(perunit notation)을 사용했으며, 전기자의 1상저항은 각종 Reactance ( $X_{x}$, $X_{q}$ )의 어느것 보담도 극소치임으로 실제계산에는 무시했으나 과도전류의 변화를 좌우하는 감쇠정수[decrement factor)에는 큰 영향을 준다는 것이 규명되었다. 해석결과로서 3상단락전류의 초기치는 특수치보다 훨씬 큰 이유로서 단락전류가 계자자속을 약하게 만들어 그 반동으로 계자회로에 일정자속을 유지하기 위하여 부문적으로 개자전류가 증대함을 알게되었고, 단락전류의 직축분과 횡축분의 구성분이 규명검토되었고, 발전기의 돌발단락저류는 일반적으로 직류분, 기본파교류분 및 제2조파등을 포함하나 그 전부가 시정수의 역수인 감쇠정수에 지배되어서 지수함수곡선에 따라 감쇠되어 결국에는 지속단락전류에 귀착한다는 사실과 3상단락은 평형단락사고임으로 영상전류는 영이며 각상과도전류의 위상차가 120.deg.라는 것엔 변함이 없다는 것과 끝으로 철극기를 정격속도로 운전해 놓고 이것을 여자해서 무부하전압을 수기시켜 그의 3상전단자를 돌연 단락해서 그의 과도전류의 파형을 Oscillograph로 촬영하면 본론에서 해석한 결과식의 그것과 일치하게 됨을 알 수 있을 것이다.것이다.

• The Safety technology
• /
• no.196
• /
• pp.26-28
• /
• 2014

한국동서발전(사장 장주옥)은 지난 2001년 한국전력공사 발전부문에서 분리 설립된 우리나라의 대표적인 발전회사 가운데 하나다. 그 명성에 걸맞게 이곳은 당진화력본부와 울산화력본부, 호남화력발전처, 동해화력발전처, 일산열병합발전처 등을 운영하면서 국가 경제를 뒷받침하고 있다. 그만큼 이곳에서는 안전을 기업경영의 최우선 가치로 내세우고 있다. 만에 하나 전력 공급이 중단될 경우 사회 경제적으로 엄청난 영향을 미치기 때문이다. 특히 일산열병합발전처(처장 김치완)는 여느 곳보다 남다른 안전관리를 전개해 나가고 있는 것으로 유명하다. 최근 안전보건공단으로부터 무재해 19배수를 인증받는 것이 이를 증명하고 있다. 시스템에 의한 빈틈없는 안전관리를 바탕으로 무재해 현장을 조성하고 있는 한국동서발전(주) 일산열병합발전처를 찾아가 봤다.

• The Transactions of the Korean Institute of Electrical Engineers A
• /
• v.48 no.5
• /
• pp.643-649
• /
• 1999

In this paper, we proposed that ｉ) noise-tolerant four kinds of AM(Amplitude Modulation)-FM(Frequency Modulation) demodulators are designed, ⅱ) we derived undersampling frequency through the product via energy operator of the monocomponent AM-FM signals separated form two-component AM-FM signals, and ⅲ) these four kinds of AM-FM demodulators detect respectively information signals of the IA(Instantaneous Amplitude) and IF(Instantaneous Frequency) by undersampling frequency to be different each other from the undersampled monocomponet AM-FM signals. Particularly, the proposed algorithm can control undersampling frequency by an integer factor. And these efficient AM-FM demodulators are well worked with the undersampled AM-FM signals.

• The Transactions of the Korean Institute of Electrical Engineers C
• /
• v.49 no.11
• /
• pp.640-648
• /
• 2000

We have developed a synchronously switched cyclic capillary electrophoresis (CE) separator that is fabricated on a silicon substrate and glass containing reservoirs, Au electrode, and isolated channels. The advantage of a cyclic separator is the high resolution and ability to separate each sample to the designated reservoir from mixed samples. This approach makes it possible to reduce the supplied voltage and the total size. Another goal of this work is to introduce the methodolgy of electroosmosis flow(EOF) to silicon substrate and to separate DNA samples using a modified double-T injector.

• Proceedings of the KIEE Conference
• /
• 2007.07a
• /
• pp.820-821
• /
• 2007

'90년대 이후 세계의 전력산업은 효율성 향상 및 사회적 편익 증진을 위해 독점에서 경쟁체제로 전환되고 있다. 우리나라도 01. 4월 발전, 송배전 및 판매가 통합된 전력회사에서 발전부문을 분할하여 별도의 6개 발전회사로 분리했고, 전력거래소를 신설하여 변동비반영 전력시장을 개설하였다. 그러나 변동비반영 전력시장은 각 참여자들의 가격입찰을 허용하지 않고 있고, 수요측 가격입찰도 허용하지 않는 시장이다. 따라서 설비예비력, 운영예비력 등 예비력과 에너지 시장에서 수요자원의 참여가능성과 참여방법을 제시하고자 한다.

• Journal of the Korean Society for Railway
• /
• v.11 no.1
• /
• pp.81-94
• /
• 2008

Recently, most of countries have been adopting the policies that aim to deal with the Problems of road congestion, environmental problems and the decreasing the volume of rall. A vital important subject is the reform of railways. Actually, the reform of railways has been carried out in various kind of ways, however the most epoch-making policy has been privatization of railways. Historically, Japan made the first step when it carried out regional privatization, unifying the infrastructure and operation. It created a 6 passenger enterprises and 1 freight enterprise. Meanwhile, in the case of the UK, discussion about rail privatization started the middle of 1980 and was implemented in 1994. It was implemented according to a functional division based on a separation of infrastructure and operation, creating a lot of different enterprises. With regard to the UK and Japan, there have been some debates about the methods of privatization, in particular, some scholars suggest that the rail accidents in the UK are a result of division of the infrastructure and operation. In addition to, some insist that the accident which occurred on 27th April 2005 at Hukujiyama in Japan was also attributable to the emphasis on profitable management. This paper examines the process and outcomes of rail privatization between the UK and Japan, especially focusing on different methods of privatization. This paper may provide some lessens for rail privatization policy. First, the rail privatization policy needs a enough time to complete the scheme. Second it is require to participate in the consumer, mass communication and rail of ncers who are involved the operation. Third, it is essential to have a huge investment, high technology and strong organization to drive.

• Journal of Korean Society of Steel Construction
• /
• v.10 no.4 s.37
• /
• pp.657-666
• /
• 1998

This study presents an effective dual algorithm for the optimal design of steel structures with displacement constraints. The dual method can replace a primary optimization problem with a sequence of approximate explicit subproblems with a simple algebraic structure. Since being convex and separable, each subproblem can be solved efficiently by the dual method. Specifically, this study uses the principle of virtual work to obtain the displacement constraint equations with an explicit form and adds the linear regression equation expressing the relationships between the cross-section properties to the dual algorithm to reduce the number of design variables. Furthermore, this study deals with the discrete optimization problem to select members with the standard steel sections. Through numerical analyses, the proposed method will be compared with the conventional optimality criteria method.

• Journal of Cadastre & Land InformatiX
• /
• v.46 no.2
• /
• pp.211-224
• /
• 2016

Based on the 'Government 3.0', the government opens the public data and encourages the active use in the private sector. Recently, the spatial and statistical information that is one of the public data is being widely used in the various web business as a high value-added information. In this study, we propose an architecture of high-availability, high-reliability and high-performance open platform which can provide a variety of services such as searching, analysis, data mining, and thematic mapping. In particular, we present two different system architectures for the government and the public services, by reflecting the importance of the information security and the respective utilization in the private and public sectors. We also compared a variety of server architecture configurations such as a clustered server configuration, a cloud-based virtual server configuration, and a CDN server configuration, in order to design a cost- and performance-effective spatial-statistical information open platform.

• Environmental and Resource Economics Review
• /
• v.14 no.2
• /
• pp.381-418
• /
• 2005

From the respect of economics, environmental industry has not defined clearly since environmental services and goods are so broad to focus. Therefore many countries are using their own version of environmental industry. Hence analysis of environmental industry is very limited. In this thesis, based on the definition of Bureau Statistical Office in Korea, economic analysis for the industrial spill effect, production effect, value-added effect has been done by using 1995, 1998 I-O tables published from the Bank of Korea. Even if portion of production from environmental industry in Korea is quite low so far, forward and backward effect has quite impact on the whole industry and show strong intermediate goods. With respect to price effect.