• Nuclear Engineering and Technology
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• 제53권11호
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• pp.3543-3562
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• 2021

The methods and performance of a 3D pin-by-pin neutronics code based on the 2D/1D decoupling method are presented. The code was newly developed as an effort to achieve enhanced accuracy and high calculation performance that are sufficient for the use in practical nuclear design analyses. From the 3D diffusion-based finite difference method (FDM) formulation, decoupled planar formulations are established by treating pre-determined axial leakage as a source term. The decoupled axial problems are formulated with the radial leakage source term. To accelerate the pin-by-pin calculation, the two-level coarse mesh finite difference (CMFD) formulation, which consists of the multigroup node-wise CMFD and the two-group assembly-wise CMFD is implemented. To enhance the accuracy, both the discontinuity factor method and the super-homogenization (SPH) factor method are examined for pin-wise cross-section homogenization. The parallelization is achieved with the OpenMP package. The accuracy and performance of the pin-by-pin calculations are assessed with the VERA and APR1400 benchmark problems. It is demonstrated that pin-by-pin 2D/1D alternating calculations within the two-level 3D CMFD framework yield accurate solutions in about 30 s for the typical commercial core problems, on a parallel platform employing 32 threads.

• 수산경영론집
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• 제40권2호
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• pp.1-25
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• 2009

The major part of non-commercial food service is food service for school which has no any objective quality standards. Each school has different standard when they buy seafood for SFS(School Food Service). The research purpose is whether or not the extrinsic cues of the seafood such as price, the source origin, company image, safety standards, etc or the intrinsic cues such as fishy smell, the hardiness of fish meat, others have any effect on the seafood evaluation when school nutritionist purchase it, for more objective basis. The research method is distributing questionnaire survey through e-mail or directly visiting the schools from October 30 to November 9, 2007. The questionnaire was distributed to 70 nutritionists of food service for elementary school in Busan. Total 50 questionnaires are used as data in the statistical analysis using SPSS package software. The research results are; First, there is interaction effect between the extrinsic and intrinsic cues of seafood for SFS. That is when the school nutritionist valued on intrinsic cues of seafood such as a fishy smell, the hardiness of fish meat and etc influence on the extrinsic cues such as price, source origin, reliable circulation process, HACCP application, etc. Second, the extrinsic cues of the seafood give no effect on perceived quality. Since seafood for SFS are heavy buying, prearrangement contract and most of them using pre-treated frozen aquatics. Third, the intrinsic cues of the seafood give no effect on perceived quality. The extrinsic cues consist of 5 parts namely "opening about quality", "source origin", "company image", "safety/standards" and "price/package". However, "safety/standard" was the only affecting factor to perceive quality. The reason is that in fact they have no standards or any document proving the quality of the seafood unless safety standards factor. Last, the perceived quality is an important factor for perceived value and purchase intention. It is showed that there is a path to form a willing to buy through the perceived value after school nutritionist recognizes the perceived quality.

• 한국생물공학회:학술대회논문집
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• 한국생물공학회 2001년도 추계학술발표대회
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• pp.430-433
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• 2001

본 실험은 erinacine 을 생산하는 Hericium erinaceus 균사체의 최대생산을 목적으로 기본배지를 토대로 수행되었다. 따라서 선정된 몇가지 대표적 carbon source와 nitrogen source를 비교 ${\cdot}$검토하였다. 그 결과 carbon source에서는 glucose에서 다른 source 에 비하여 높은 균사체 생산량을 보여주었으며 nitrogen source에서는 yeast extract에서 높은 균사체 생산량을 보여주었다. 또한 C/N ratio 검토를 근거로 본 실험에서는 glucose 20g/L 와 yeast extract 10g/L를 modified medium으로 선정하였다. 그 결과 균체량은 11.78g/L, Polysaccharide는 l.03g/L 로 측정되었다.

• 전력전자학회:학술대회논문집
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• 전력전자학회 1998년도 Proceedings ICPE 98 1998 International Conference on Power Electronics
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• pp.524-528
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• 1998

The voltage-source inverters are normally equipped with an electrolytic capacitor in their DC link, however, the electrolytic capacitor has several disadvantages such as increasing size, limiting converter life and reliability. Therefore, several approaches for removing the DC link capacitor have been studied by the authors. This paper proposes a new voltage-source inverter without DC link components. To reduce waveform distortion of the AC source current, the current-controlled PWM-rectifier with di/dt feedback is introduced. The di/dt feedback gain and LC parameters are investigated by calculation for a 0.75kW induction motor driven by this inverter. The calculated AC source currents maintain nearly sinusoidal waveforms with a unity power factor.

• 대한가정학회지
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• 제47권10호
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• pp.1-11
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• 2009

The purpose of this study was to explore differences in style preference, information source, and store selection behaviors of Korean and Chinese wedding dress shoppers. Data obtained from 141 Chinese and 143 Korean females were analyzed through descriptive analysis, t-test, cross-tabulation and factor analysis. Results for Chinese and Korean consumers depended on the marketer-driven information source as well as on the consumer-driven information source. Both groups considered the aesthetics of the wedding dress as the most important criterion for store selection. There were some differences between Chinese and Korean consumers in style preferences and store selection criteria. Chinese consumers liked a wider range of wedding dress styles compared to Korean consumers. Also, Chinese consumers regarded fashionability as more significant whereas Koreans considered economic benefits more importantly when selecting stores for a wedding dress.

• 전기학회논문지
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• 제59권7호
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• pp.1242-1247
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• 2010

In this study, the heat source distributions at the end side and the center of the electrode are analyzed to estimate the electrical stress due to the harmonics from the nonlinear loads. The governing equation at the analysis area of low voltage condenser are numerically solved using the finite element software package to analyze the effects of heat source distribution due to the 5th and 7th harmonics, which can exist normally in the distribution network and can be applied to the low voltage condenser. Finally, the heat source distribution from the harmonics is compared and analyzed with the heat source distribution from the fundamental component of the applied voltage.

• 전력전자학회논문지
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• 제18권1호
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• pp.1-9
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• 2013

This paper proposes a ST(Switched Trans) quasi Z-source inverter using a Switched Trans Cell combing the characteristics of a Switched Inductor Cell and Trans. A DC link inductor of the conventional quasi Z-source inverter is alternated with Switched Trans Cell of the proposed ST quasi Z-source inverter. Trans Cell of the proposed method consists of one Trans and two diodes, and the proposed method has higher and more various boost function than the conventional quasi Z-source inverter by simply changing the turns ratio of primary and secondary of the Trans. The validity of the proposed ST Z-source inverter was confirmed by PSIM simulation and a DSP based experiment under the input voltage 48V and output phase voltage 30V. As a result, when compared with the traditional quasi Z-source inverter, the proposed method has the advantage of the low voltage stress under the same output voltage condition of the voltage.

• 한국산학기술학회:학술대회논문집
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• 한국산학기술학회 2004년도 춘계학술대회
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• pp.193-197
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• 2004

The four-leg Voltage Source Converter(VSC) can use the DC link voltage effectively by the 3-D SVPWM method. Hence the DC battery voltage can be reduced by $15\%$ in comparison to that of the conventional line-interactive UPS system. In this paper a novel line interactive Uninterruptible Power Supply(UPS) using the two four-leg VSCs is proposed. One VSC is in parallel with the ac link reactor of the power source side, and the other is in series with the load. The parallel four-leg voltage source inverter controls the three-phase line voltage independently in order to control the line reactor current indirectly. It eliminates the neutral line current and the active ripple power of the source side using the pqr theory so that unity power factor and the sinusoidal source current can be achieved even though both the source and the load voltages have zero sequence components. The series four-leg voltage source inverter compensates the line voltage and allows it to be balanced and harmonic-free. Both of the parallel and series four-leg voltage source inverters always act as independently controllable voltage sources, so that the three-phase output voltage shows a seamless transition to the backup mode. The feasibility of the proposed UPS system has been investigated and verified through computer simulations results.

• 전력전자학회:학술대회논문집
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• 전력전자학회 1999년도 전력전자학술대회 논문집
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• pp.362-365
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• 1999

In this paper, the method of reducing harmonics and correcting of power factor in single PWM converter associated with diode rectifier and boos converter is studied. The ac-dc converter in which the harmonic distortion in the input current is reduced using a third harmonic injected PWM is proposed. A lower switching power loss and easy configuration o control circuit are obtained by adopting discontinuous current mode. Simulation and experimental results of ac-dc converter with 5[KHz] switching frequency are presented and correction of power factor and reduction of total harmonic distortion was established.

• 한국데이터정보과학회:학술대회논문집
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• 한국데이터정보과학회 2004년도 춘계학술대회
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• pp.131-139
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• 2004

Robust parameter design is to identify appropriate settings of control factors that make the system's performance robust to changes in the noise factors that represent the source of variation. In this paper, we introduce a factor analysis approach to simultaneously optimize multiple quality characteristics in the robust parameter design. An example is illustrated to compare it with already proposed method.