• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2005년도 춘계학술대회
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• pp.422-426
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• 2005

This experimental study represents the results of an analysis on the characteristics of flux density distribution in the focal region of solar concentrator. The characteristics of flux density distributions are investigated to optimally design and position a cavity receiver. This was deemed very useful to find and correct various errors associated with a dish concentrator. We estimated the flux density distribution on the target placed along with focal lengths from the dish vertex to experimentally determine the focal length. It is observed that the actual focal point exists when the focal length is 2.17m. The total integrated power and percent power was 2467W and $85.8\%$, respectively, in the case of small dish, and also 2095W and $79\%$, respectively, in the case of KIERDISH II. As a result of the percent power within radius, approximately $90\%$ of the incident radiation is intercepted by about 0.06 m radius. The minimum radius of receiver in KIERDISH II is found to be 0.15m and approximately $90\%$ of the incident radiation is intercepted by receiver aperture.

• 전기학회논문지P
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• 제58권1호
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• pp.79-84
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• 2009

In order to increase the capacity of the superconducting fault current limiter(SFCL), the current and voltage grades of the SFCL must be increased. As a method for the increase of the current and voltage grades of the SFCL, we compared the various characteristics between the flux-lock type SFCL "With three superconducting units connected in series and the transformer type SFCL using the transformer with three secondary circuits. One of three superconducting units had not quenched in the flux-lock type SFCL. Therefore, the unbalanced power burden happened because of the voltage difference generated by unbalanced quenching between the superconducting units. In the meantime, the three superconducting units were all quenched in the transformer type SFCL using the transformer, and the voltage difference generated between the superconducting units was decreased. Therefore, the difference of critical characteristics was complemented by distribution of fault current in accordance with the turn's ratio between primary and secondary windings. The unbalanced power burden of the superconducting units was reduced due to flux-share between the superconducting units in the transformer. In conclusion, the capacity increment of the SFCL using a transformer was easier due to equal distribution of voltages generated by simultaneous quench of the superconducting units. We think that the characteristics is improved more because of the decrease of saturation in the iron core if the secondary winding is increased in the SFCL using the transformer.

• 대한조선학회논문집
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• 제35권1호
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• pp.98-106
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• 1998

멤브레인형 가스운반선의 경우 화물창들 사이에 cofferdam을 두어 격리시키고 있는데 이 경우 극 저온 액체 화물의 영향으로 cofferdam 실내 온도는 약 $-40^{\circ}C$내외로 떨어지게 된다. 그 결과 cofferdam 및 화물창을 구성하는 bulkhead는 구조 부재로서의 허용 강도를 만족하는 온도를 유지할 수 없게 된다. 결국 heating system을 사용하여 cofferdam 실내 온도를 최소한 $5^{\circ}C$까지 올려야 하는데, 소요 pipe의 길이 산정을 위한 heat flux 산출과 pipe의 배치가 우선적으로 요청된다. 본 연구에서는 다양한 설계 조건에서의 cofferdam 내 heat flux를 각 compartment들 간의 연성 효과를 고려하여 구하고 이를 기존 계산서들과 비교 검토하여 그 타당성을 검증하였고 이를 토대로 heating system에 필요한 pipe의 길이를 산정하였다. 아울러 현재의 heating system의 대안으로 fin을 부착한 pipe로 구성된 heating coil system을 제시하고 그 효율을 비교하였다.

• Nuclear Engineering and Technology
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• 제53권2호
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• pp.430-438
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• 2021

The spatial distribution of neutron flux or reaction rate was calculated by cell or mesh tally in traditional Monte Carlo simulation. However, either cell or mesh tally leads to the increase of memory consumption and simulation time. In this paper, the function expansion tally (FET) method was developed in Reactor Monte Carlo code RMC to solve this problem. The FET method was applied to the tallies of neutron flux distributions of uranium block and PWR fuel rod models. Legendre polynomials were used in the axial direction, while Zernike polynomials were used in the radial direction. The results of flux, calculation time and memory consumption of different expansion orders were investigated, and compared with the mesh tally. Results showed that the continuous distribution of flux can be obtained by FET method. The flux distributions were consistent with that of mesh tally, while the memory consumption and simulation time can be effectively reduced. Finally, the convergence analysis of coefficients of polynomials were performed, and the selection strategy of FET order was proposed based on the statistics uncertainty of the coefficients. The proposed method can help to determine the order of FET, which was meaningful for the efficiency and accuracy of FET method.

• Journal of Magnetics
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• 제22권2호
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• pp.315-325
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• 2017

Magnetically suspended sensitive gyroscopes (MSSGs) provide an interesting alternative for achieving precious attitude angular measurement. To effectively reduce the measurement error caused by the non-uniformity of the air-gap flux density in a MSSG, this paper proposes a novel compensation method based on measuring and modeling of the air-gap flux density. The angular velocity measurement principle and the structure of the MSSG are described, and then the characteristic of the air-gap flux density has been analyzed in detail. Next, to compensate the flux density distribution error and improve the measurement accuracy of the MSSG, a real-time compensation method based on the online measurement with hall probes is designed. The common issues caused by the non-uniformity of the air-gap flux density can be effectively resolved by the proposed method in high-precision magnetically suspended configurations. Comparative simulation results before and after compensation have verified the effectiveness and superiority of the proposed compensation method.

• Korean Chemical Engineering Research
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• 제46권3호
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• pp.639-645
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• 2008

십자형 응집-한외여과 막분리 공정 운전시 응집조건에 따른 영향을 살펴보면 급속교반-UF 공정과 응집-침전-UF 공정에서 투과 flux의 변화는 크게 나타나지 않았으며 UF막의 막오염 억제 측면에서는 응집전처리공정으로서 1분간의 짧은 급속혼화만으로도 충분한 것으로 나타났다. 교반강도에 따른 투과 flux의 변화결과 교반강도에 따라 형성되는 floc의 크기가 거의 유사하게 형성되어 교반강도에 따른 영향은 나타나지 않았다. 응집제 주입량에 따른 투과 flux변화를 살펴보면 응집제 주입량이 증가함에 따라 유기물의 제거가 크게 일어나 유기물 부하의 감소와 floc의 크기가 증가함에 따라 다공성 케이크층의 형성에 따른 막저항의 감소로 인하여 투과 flux가 향상되었다. 막의 재질과 전처리 응집공정적용에 따른 여과메카니즘 분석결과 막의 재질에 따라서는 친수성 재질의 막에 비하여 소수성 재질의 막의 경우 막의 공극속으로 입자의 침투가 발생하여 침적 흡착되는 현상과 막의 표면에서 형성되는 cake층에 의한 투과 flux 감소가 주원인이 되었으며 응집공정을 전처리공정으로 적용시 UF단독공정에 비하여 막오염 발생이 저감되었다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1996년도 하계학술대회 논문집 A
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• pp.225-227
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• 1996

The paper is described the analysis of spacing flux distribution, EMF and torque pulsation in unbalanced voltage squirrell-cage induction motor using finite element method.

• 한국결정성장학회지
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• 제10권2호
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• pp.128-133
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• 2000

Numerical analysis of the transport phenomena in an inductively coupled plasma reactor was conducted with two-dimensional axisymmetric model including the electromagnetic field model, electron and species density models. The spatial distribution of the charged species in the ion flux to the wafer have been calculated to examine the influence of the process conditions including antenna and reactor geometry. The antenna radius had a significant influence on the plasma state and axial ion flux distribution.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년도 추계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.95-97
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• 2006

Cogging torque is often a principal source of vibration, noise and difficulty of control in BLDC motors. Therefore, this paper will present a design method of magnetization system with sinusoidal air-gap flux density distribution of Nd-Fe-B magnets in ring type for reduction of Vibration and Noise and low manufacturing cost.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1988년도 추계학술대회 논문집 학회본부
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• pp.333-336
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• 1988

This paper is presented the two dimensional flux distribution analysis of a double sided linear induction moter with the end effects and the transeverse edge effects, which is caused by the finite length and width of the stator iron. The results are expected to be used to increased the understanding of DLIM characteristics and design