• 한국응용과학기술학회지
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• 제39권4호
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• pp.535-541
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• 2022

The radical reaction position was calculated by varying the calculation level for ACEL and ANT, which are detected with the highest frequency and concentration in PAHs pollution sites. The results of each calculation level were compared and evaluated with the existing literature. HF, B3LYP, B3LYP-D, and MP2 were used as the method for each level used for calculation. Except for HF, the MK charge by B3LYP, B3LYP-D, and MP2 was consistent with the experimental results. It was found that the dispersion effect was negligible in the calculation of ACEL and ANT because the calculation results by the B3LYP and B3LYP-D methods were the same. In particular, it was found that the MK charge calculation result by MP2 agrees well with the product/PAH ratio obtained as a result of the experiment. Considering the calculation cost, it would be preferable to use B3LYP to predict the radical reaction site of ACEL and ANT. However, considering the product/PAH ratio, it takes more time to calculate, but it is judged that it is better to use the MP2.

• 한국학교수학회논문집
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• 제2권1호
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• pp.43-53
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• 1999

Two (second-grade) classes of Yu-song middle school were chosen to research the effect of the visualization in the learning of probability calculation at a middle school. One class, as an experiment class, was taught the probability calculation of probability unit by the visualization learning and the other, as a controlled class, was taught it by the traditional lecture, and then through the writing tests there was a verification on the effect of right after test and the delaying test after 3 weeks to examine the learning effect of high- and low-level groups. It was difficult for the students to visualize the problems of the probability calculation, but I suggested simple models to the students and helped them to learn meaningfully. As a result of this study, there showed statistically significant difference in high-level group in the right after test.(P< .05) In the delaying test after 3 weeks, there also showed statistically significant marks only in high-level group.(P< .05) The visualization in the learning of probability calculation took more affirmative effect in the experiment class than the comparative class only in high-level group. The students in low-level group has difficulties in the visualization activities, but all the students in high-and low-level group thought the visualization was a great help to them in learning probability calculation.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2008년도 추계학술대회 논문집 전력기술부문
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• pp.50-52
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• 2008

We have limited the transfer power to capital area below a certain level which is called "The Capital Area Transfer Power Limit", and calculated on every Thursday for the application next week. This level is very important in our network operation, because if this level is not set properly, our power network can be fallen under great danger in case of a fault among the transfer power line. But the calculation procedure for the limit level is so complicated and iterative that it mace us spend much time and do much work. So, when a sudden trip of the related facility to the limit level we can't recalculate the limit level fast enough. And this can drop our network reliability below our standards, therefore our network can be dangerous. To avoid this kind of problems, we have figured out a method to calculate simply the limit level. That method uses the index related to the level. We think this method can make short of the calculation procedures for the level. This paper deals with the simplified method for the calculation of the level limit.

• Nuclear Engineering and Technology
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• 제53권1호
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• pp.30-43
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• 2021

In the 2D/1D method, a global adjoint CMFD based on the generalized equivalence theory is built to synthesize the 2D radial MOC adjoint and 1D axial NEM adjoint calculation and also to accelerate the iteration convergence of 3D whole-core adjoint transport calculation. Even more important, an advanced yet accurate two-level (TL) CMFD acceleration technique is proposed, in which an equivalent one-group adjoint CMFD is established to accelerate the multi-group adjoint CMFD and then to accelerate the 3D whole-core adjoint transport calculation efficiently. Based on these method, a new code is developed to perform 3D adjoint neutron flux calculation. Then a set of VERA and C5G7 benchmark problems are chosen to verify the capability of the 3D adjoint calculations and the effectiveness of TL CMFD acceleration. The numerical results demonstrate that acceptable accuracy of 2D/1D adjoint calculations and superior acceleration of TL CMFD are achievable.

• 한국초등수학교육학회지
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• 제21권1호
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• pp.23-47
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• 2017

본 연구에서 초등학교에서 분수에 대한 사칙연산의 학습을 마친 시점에 있는 6학년 학생들을 대상으로 학업성취수준에 따라 분수의 사칙연산 과정에서 발생하는 오류는 어떤 것들이 있는지 분수의 사칙연산 유형별로 오답률을 분석하였고, 학업성취수준에 따라 각각의 분수의 오류유형에는 어떤 차이가 있는지 알아보았다. 분수의 사칙연산에서 진분수 사이의 계산보다는 대분수가 같이 있는 계산에서 가장 높은 오답률을 보이고 있다. 특히 동분모 분수의 계산보다는 이분모 분수에서의 계산에서 높은 오답률을 보이고 있는데 학생들이 이분모 분수에서 통분을 하는 것을 어려워하는 것으로 나타났다. 분수의 곱셈에서는 상 수준과 중 수준의 학생들은 계산오류에서 가장 높은 오답률을 보이고 있으며, 하수준의 학생들은 역수오류가 가장 높은 오답률을 보이고 있다.

• 한국산업보건학회지
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• 제31권3호
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• pp.274-285
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• 2021

Objectives: The question of whether the level of fees paid to working environment measurement agencies is appropriate has long been a matter of concern to the government. In addition, measurement institutions express dissatisfaction with their level of compensation, which has a great influence on the evaluation of a subject's policy. This study is intended to find a way to appropriately calculate working environment measurement fees. Methods: We looked at the principle of fee determination as a basic theory of fee calculation used in fee calculation, the legal and academic aspects of the general method of fee calculation, and government cost calculation standards. Furthermore, we reviewed the research methods applied so far to derive a method of calculating fees appropriate for this environment. Results: The working environment measurement environment is different from other commission calculation environments. The other environment is to appropriately calculate the service price provided by a monopoly public enterprise, while the situation is to appropriately calculate the fees provided by competitive private enterprises. Therefore, the service delivery environment and the delivery entity are different. In this case, the appropriate method of calculating service fees would be competitive pricing. There have also been many problems under the method of calculation by service cost. Conclusions: First, the working environment measurement fee requires an accounting correction of endogenous variables. Second, the theory of calculating fees appropriate for this situation is appropriate for competitive pricing that applies to private competitors. Third, the government should make efforts to make the service supply market a fully competitive market while ensuring that the service fee level is determined at the marginal cost level. Fourth, economically, research on marginal cost levels is needed.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2002년도 추계학술대회 논문집
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• pp.171-174
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• 2002

This paper deals with a novel method in order to analyze the harmonic characteristics in the multi-level inverter. Generally, the magnitude of harmonic components is different according to the carrier PWM techniques, modulation Index(Mi), and the level of multi-level inverter The previous papers analyzed the harmonic characteristics from the viewpoint of the space vector. Hence, the calculation of the harmonic vector becomes difficult and complex in 4-level or more than S-level. However, the proposed method of this paper reduced an amount of calculation and simplified the process of calculation by using the relationship between reference voltage and output phase voltage to load neutral. This paper analyzed the harmonic and it is applied to the multi-carrier PWM techniques in 5- level and other-level of cascaded inverter system.

• 인터넷정보학회논문지
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• 제6권2호
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• pp.85-97
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• 2005

1985년에 처음 등장했던 테트리스는 많은 시간이 지난 지금에도 많은 유저들에게 사랑 받는 게임이 되었다. 지금까지의 테트리스는 줄이 삭제 될 때마다 삭제된 줄의 수에 따라 점수를 주는 방식을 채용하였고, 연속 공격 등에 관해 가산점을 부여해주었다. 그러나 이러한 점수 산출방식은 너무 일정하고 단순한 패턴을 주었다. 본 논문에서는 기존의 점수 계산 방식과는 다른 단계별 점수 계산 방식을 통하여 새로운 테트리스 게임 시스템을 설계 및 구현하고자 한다. 즉, 이는 전에 삭제된 줄의 수와 현재 삭제된 줄의 수를 비교하여 기본 점수에 가산점을 부여하는 방식이다. 단계별 점수산출방식을 이용하여 기존의 테트리스에서 한층 더 진보된 테트리스의 전략적인 이용을 가능하게 해 줄 것이다.

• Journal of Power Electronics
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• 제16권4호
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• pp.1598-1611
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• 2016

In some special occasions with strict size requirements, such as mine hoists, improving the design accuracy of the forced-air cooling systems of NPC three-level inverters is a key technology for improving the power density and decreasing the volume. First, a fast power-loss calculation method was brought. Its calculation principle introduced in detail, and the computation formulas were deduced. Secondly, the average and dynamic power losses of a 1MW mine hoist acting as the research target were analyzed, and a forced-air cooling system model based on a series of theoretical analyses was designed with the average power loss as a heat source. The simulation analyses proves the accuracy and effectiveness of this cooling system during the unit lifting period. Finally, according to an analysis of the periodic working condition, the maximum power-loss range of a NPC three-level inverter under multi cycle operation was obtained and its dynamic power loss was taken into the optimized cooling system model as a heat source to solve the power device damage caused by instantaneous heat accumulation. The effectiveness and feasibility of the optimization design based on the dynamic power loss calculation of the maximum power-loss range was proved by simulation and experimental results.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2009년 추계학술대회논문집
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• pp.193-200
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• 2009

Recently, there have been efforts to construct hybrids among the existing methodologies for multiphase flow such as VOF, Level Set, and Front Tracking with the intention of facilitating simulations of general three-dimensional problems. As one of the hybrid method, we have developed the Level Contour Reconstruction Method (LCRM) for general three-dimensional multiphase flows including phase change. The main idea was focused on simplicity and a robust algorithm especially for the three-dimensional case. It combines characteristics of both Front Tracking and Level Set methods. While retaining an explicitly tracked interface using interfacial elements, the calculation of a vector distance function plays a crucial role in the periodic reconstruction of the interface elements in the LCRM method to maintain excellent mass conservation and interface fidelity. In addition, compact curvature formulation is incorporated for the calculation of the surface tension force thereby reducing parasitic currents to a negligible level.