• 전자공학회논문지D
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• 제35D권11호
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• pp.31-37
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• 1998

감쇠기와 위상 변환기로 구성된 진폭/위상 조정 회로는 위상/이득 상호 결합 현상을 일으켜서 최적 동작점을 찾는 데에는 많은 조정 시간이 필요하다. 본 논문에서는 입력신호의 진폭과 위상을 제어하여 출력하는 벡터 감쇠기를 설계하였다. 종전의 벡터 감쇠기는 감쇠기의 위상 변화 특성을 무시하였으나, 본 논문의 벡터 감쇠기는 감쇠기의 위상 변화 특성을 보상하였다. 이 벡터 감쇠기는 0°/180° 위상 변환기, 저위상 변화 감쇠기등으로 이루어지는데, 0°/180° 위상 변환기는 중심주파수 881MHz에서 0°/179.9° 위상 변환 특성을 얻었고, 저위상 변화 감쇠기는 감쇠량이 25dB일 때 위상 변화가 3.6° 이내, 입출력 반사 특성이 -20dB이하를 얻었다. 구현된 벡터 감쇠기는 출력 신호 공간의 직교 좌표 평면을 정확히 표현할 수 있음을 확인하였다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2005년도 하계학술대회 논문집 Vol.6
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• pp.54-56
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• 2005

In this paper, we investigated the quench characteristics of HTSC elements in the integrated three-phase flux-lock type SFCL according to fault types such as the single-line-to-ground fault, the double-line-to-ground fault, the line-to-line fault and the three-line-to-ground fault. The integrated three-phase flux-lock type SFCL was the upgrade version of the single-phase flux-lock type SFCL. The structure of the integrated three-phase flux-lock type SFCL consisted of three-phase flux-lock reactor wound on an iron core with the ratio of the same turn between coil 1 and coil 2 in each phase. When the SFCL is operated under the normal condition, the flux generated in the iron core is zero because the flux generated between two coils of each single phase is canceled out. Therefore, the SFCL's impedance is zero, and the SFCL has negligible influence on the power system. However, if a fault occurs in any single-phase among three phases, the flux generated in the iron core is not zero any more. The flux makes HTSC elements of all phases quench irrespective of the fault type, which reduces the current of fault phase as well as the current of sound phase. It was observed that the fault current limiting characteristics of the suggested SFCL were dependent on the quench characteristics of HTSC elements in all three phases.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2000년도 ITC-CSCC -1
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• pp.237-240
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• 2000

We have proposed a simple method based on IIR filters for realizing sound image localization. How-ever the nonlinearity of phase characteristics of the IIR filters, which are used for sound image localization, cause decrease of the localization accuracy. In this paper we investigate the influence of phase characteristics on the sound localization. Head-related transfer functions (HRTFs) of a dummy-head are approximated by the IIR filter. We carried out sound image localization experiment with 2-loudspeaker reproduction using the approximated HRTFs. Then the errors which obtained from experiments were compared with the theoretical values which were estimated from the phase shifts of the IIR filters. As a result there was little influence of the nonlinear phase characteristics of the IIR fitters in the localization on the horizontal plane.

• 건축역사연구
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• 제23권2호
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• pp.39-52
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• 2014

This study researched changes over time regarding the location and spatial characteristics of modern meteorological stations, and examined the characteristics of modern meteorological station construction using the location and spatial characteristics of the Busan Meteorological Station. First, meteorological stations were located in port areas, and then moved to high altitude areas for stable meteorological observation beginning in the transition phase. Here, office buildings and residences were joined, but were separated due to the increase in functions from the stabilization phase. Second, as for spatial composition, in the establishment phase, existing buildings were used, and the scale of newly constructed buildings differed according to time and area. However, after the Japan-Korea Annexation, with increased funds and increased observation equipment, floor plans subdivided by function started to appear. In the stabilization phase, space was subdivided with redundancy due to the increase in functions. In the wartime transition phase, '一' shaped floor plans with redundancy became the norm. Meanwhile, the location of the maritime customs where the first meteorological observations took place after the opening of the ports, and the location and construction of the Busan Temporary Observatory built in the meteorological observation transition phase (1905) were investigated. Also, through the investigation of the Busan Meteorological Observatory, newly constructed before 1934, the location and spatial characteristics of modern era meteorological observatories were studied.

• 전기학회논문지
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• 제63권1호
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• pp.54-62
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• 2014

This study deals with the design and characteristics analysis on a linear synchronous motor (LSM) with a long stator and phase concentrated winding (PCW) to apply for a propulsion system such as a roller coaster for leisure facilities. First of all, the required propulsion force of LSM is computed and its design with double sided permanent magnets (PMs) and a phase concentrated winding is processed. The phase concentrated winding is composed of a module with each A, B, and C phase unlike an conventional concentrated winding (CW). It has an advantage of the installation and manufacture, compared to the conventional concentrated winding in the propulsion system for leisure facilities that have a long acceleration area and stator configuration placed on rail continuously. Thus, the design for the propulsion system and characteristics comparison between the phase concentrated winding and concentrated winding are carried out in this paper. Also, the analysis on dynamic characteristics is conducted to confirm the performance at operation.

• Tribology and Lubricants
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• 제16권1호
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• pp.33-38
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• 2000

Abstract- In this paper tribological characteristics of solid and liquid phase sintered W/C-35%Ni tappets were investigated. Three test methods were performed to investigate the wear and surface damage mechanism of sintered tappets. First, block-on-ring wear test was performed to investigate the wear characteristics under pure sliding condition. Second, simplified cam and tappet tests (called component wear test hereafter) were carried out to simulate the real contact history of cam and tappet. Also, after the test, contact surfaces were analyzed with scanning electron microscope to study the wear mechanism. As a final screening, engine dynamo tests were performed. Results showed that in the block on ring sliding wear test, solid phase sintered specimens showed superior wear resistance to liquid phase sintered specimens. The component wear tests and engine dynamo tests also showed the same results. Therefore, in these tests, solid phase sintered tappet material revealed superior wear resistant properties to liquid phase sintered one.

• 한국통신학회논문지
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• 제24권6B호
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• pp.1142-1148
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• 1999

본 논문에서는 Ku-밴드의 마이크로파 대역에서 위상배열 안테나에 사용 가능한 결합선로를 이용하여 위상천이기에서 기존에 고려하지 않았던 주파수에 따른 분산특성을 전파(Full-wave) 해석방법인 SDA(Spectral Domain Approach)를 사용하여 정확히 해석하였다. 또한 비대칭 결합선로를 사용하는 위상천이와 유전치 덮개층이 부가된 위상천이기의 설계를 제안하였다. 현재 사용되고 있는 대칭 결합선로를 이용한 쉬프만 위상천이기와 비교하여, 이에 대한 위상응답의 특성변화에서 통과대역의 위상편차가 줄고 대역폭이 확대되어 광대역 특성이 개선되는 것을 이론적으로 해석하고 실험을 통하여 검증하였다.

• Journal of Advanced Marine Engineering and Technology
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• 제30권6호
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• pp.685-692
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• 2006

In a general centrifugal pump, if it is operated in a two-phase flow the activity of the impeller usually degrades and occasionally losses its function. However, the effect of break down of centrifugal pump due to entrained air has not been clarified yet. This paper shows the air-water two-phase flow characteristics of closed type and semi-open type impellers. In a sing1e-phase flow, closed-type impeller has higher efficiency and head. But in air-water two-phase flow semi-open type impeller's rates of decreases of efficiency and head are decreased.

• Journal of international Conference on Electrical Machines and Systems
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• 제2권1호
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• pp.77-82
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• 2013

By using simulation, compensating characteristics of a voltage sag compensator utilizing single-phase matrix converter is examined. System configuration is described and mathematical model of single-phase matrix converter is derived by using the state space averaging method. In addition, the single-phase matrix converter is stabilized by phase-lead compensation. Finally, compensating characteristics of the compensator is investigated for 500 W R-L load and it is demonstrated that the compensator can operate correctly for loads for the range of power factor 0.6 (lagging) - 0.8 (leading) and for up to 50% voltage sag.

• 한국전기전자재료학회논문지
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• 제17권9호
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• pp.994-1000
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• 2004

We studied the characteristics of annular phase gratings as spatial frequency filters. We first calculated the Fraunhofer diffraction patterns of annular gratings and then got the modulation transfer function (MTF) from the zeroth order Hankel transform of the intensity distribution function. Binaryphase annular grating shows higher diffraction efficiency than binary phase rectangular grating. But the MTF decreases linearly in the low-frequency region as that of rectangular grating does. The diffraction pattern of 4-phase annular grating is similar to that of 2-phase grating and hence MTFs of the two are much alike. For 8-phase annular grating, the 7th order diffracted beam is the lowest one next to the first. Consequently, the diffraction efficiency is very high and the MTF graph is curved upward. The diffracted beams except the first order are negligible and hence the MTF characteristics are more improved in the case of 16-phase grating. But the degree of improvement becomes lowered c(Impaled with 8-phase grating. We made a 16-phase annular grating and measured its MTF. The experimental result agrees well with the calculated one.