• 대한수학회보
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• 제57권1호
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• pp.219-244
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• 2020

In this paper, we approximate the solution of the coupled nonlinear Schrödinger equations by using a fully discrete finite element scheme based on the standard Galerkin method in space and implicit midpoint discretization in time. The proposed scheme guarantees the conservation of the total mass and the energy. First, a priori error estimates for the fully discrete Galerkin method is derived. Second, the existence of the approximated solution is proved by virtue of the Brouwer fixed point theorem. Moreover, the uniqueness of the solution is shown. Finally, convergence orders of the fully discrete Crank-Nicolson scheme are discussed. The end of the paper is devoted to some numerical experiments.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1997년도 하계학술대회 논문집 B
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• pp.414-417
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• 1997

We propose a decentralized $H_{\infty}$ state estimation method in the multisensor state estimation problem. The proposed method bounds the maximum energy gain from unknown external disturbances to the estimation errors in the suboptimal case. And we formulate the decentralized state estimation method in the general case of different global and local models using alternative gain equation of the $H_{\infty}$ state estimator which can calculate global state estimates from the the linear combination of local state estimates. In addition, the proposed update equation between global and local Riccati solutions can reduce unnecessary calculation burden efficiently.

• Asian Pacific Journal of Cancer Prevention
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• 제15권23호
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• pp.10293-10298
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• 2015

Background: Previous epidemiologic studies on the association between energy intake and endometrial cancer risk have only generated contradictory results. The role of energy intake in endometrial carcinogenesis thus remains unclear. To quantitatively assess the potential association between energy intake and endometrial cancer, a meta-analysis of case-control and cohort studies was here conducted. Materials and Methods: Eligible studies were retrieved via both computerized searches and review of references. Fixed-or random-effect models were used to summarize the estimates of OR with 95%CIs. Stratified analyses on study design, region and macronutrients' calorie were performed. Results: Sixteen studies met the inclusion criteria of the meta-analysis. No association between total energy intake and endometrial cancer was observed in either overall group (OR=1.11, 95%CI 0.92-1.30) or subgroups stratified by study design and region. In the specific macronutrients' calorie analysis, higher fat energy intake was found to be associated with increased endometrial risk (OR=1.72, 95%CI 1.12-2.32) while energy from carbohydrate and protein was not related to endometrial cancer risk. Conclusions: Our analysis did not support that total energy intake is related to endometrial cancer risk, in contrast to fat energy.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1999년도 학회창립 10주년 기념 1999년도 가을 학술발표회 논문집
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• pp.155-158
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• 1999

This paper discusses the validity of models to predict the compressive strength of concrete subjected to various temperature histories and the shortcomings of existing rate constant model and apparent activation energy concept. Based on the discussion, a modified rate constant model is proposed. The modified rate constant model, in which apparent activation energy is a nonlinear function of curing temperature and age, accurately estimates the development of the experimental compressive strengths by a few researches. Also, the apparent activation energy of concrete cured with high temperature decreases rapidly with age, but that cured with low temperature decreases gradually with age. Finally a generalized model to predict apparent activation energy and compressive strength is proposed, which is based on the regression results.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 춘계학술대회 논문집 전력기술부문
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• pp.172-175
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• 2001

This paper presents a new energy function reflecting the damping effect in multi-machine power systems. The Lyapunov direct method provides precise and rigorous theoretical backgrounds for stability analysis of nonlinear systems. Incorporating damping effects into accurate estimates of the domain of attraction, which is a minor but crucial point, has been attempted with long history to yield partial success for single machine systems. In this paper, the damping-reflected energy function presented in the previous work has been generalized for application to multi-machine systems. The generalized energy function is tested for the WSCC 9-bus system to show the semi-negativeness of its time derivative.

• Journal of Advanced Marine Engineering and Technology
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• 제18권1호
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• pp.73-80
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• 1994

The water ejector is a low pressure high flow rate volumetric pump. It utilize the energy of a low mass flow, high velocity stream to induce a large mass flow, low velocity stream. In addition, it has a very good resistances to cavitation compared to the other type of pumps, and the maintenance cost is practically nil. There has been enormous energy loss to supply the upper part water of dam which has large potential energy as mere irrigation water in domestic multipurpose dam. The new type of energy saving system which developed through the present study can economizes over 950,000 kWh per year by mixing the upper part water of dam with the waste water by the large water ejector. This paper estimates the economical efficiency of the new type of irrigation water pumping system, and further more, represents the change of performance characteristics of large water ejector, which was adapted to this system, according to the fluctuation of upper water level that seasonally changes.

• 경영과학
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• 제11권2호
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• pp.1-27
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• 1994

A reliability data processing MPRDP (Multi-Purpose Reliability Data Processor) has been developed in FORTRAN language since Jan. 1992 at KAERI (Korean Atomic Energy Research Institute). The purpose of the research is to construct a reliability database(plant-specific as well as generic) by processing various kinds of reliability data in most objective and systematic fashion. To account for generic estimates in various compendia as well as generic plants' operating experience, we developed a 'three-stage' Bayesian procedure[1] by logically combining the 'two-stage' procedure[2] and the idea for processing generic estimates[3]. The first stage manipulates generic plant data to determine a set of estimates for generic parameters,e.g. the mean and the error factor, which accordingly defines a generic failure rate distribution. Then the second stage combines these estimates with the other ones proposed by various generic compendia (we call these generic book type data). This stage adopts another Bayesian procedure to determine the final generic failure rate distribution which is to be used as a priori distribution in the third stage. Then the third stage updates the generic distribution by plant-specific data resulting in a posterior failure rate distribution. Both running failure and demand failure data can be handled in this code. In accordance with the growing needs for a consistent and well-structured reliability database, we constructed a generic reliability database by the MPRDP code[4]. About 30 generic data sources were reviewed and available data were collected and screened from them. We processed reliability data for about 100 safety related components frequently modeled in PSA. The underlying distribution for the failure rate was assumed to be lognormal or gamma, according to the PSA convention. The dependencies among the generic sources were not considered at this time. This problem will be approached in further study.

• Asian-Australasian Journal of Animal Sciences
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• 제8권1호
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• pp.59-66
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• 1995

Energy obtained by grazing cattle in oil palm plantations is usually used for maintenance of body functions, the construction of body tissues and pregnancy, the synthesis of milk and the conversion to mechanical energy used for activities such as walking, eating and others. In this study, attempt was made to estimate metabolizable energy (ME) requirement of grazing cattle. Models of ME requirement (MER) for maintenance, gain, pregnancy, lactation and activities were developed. ME system and units were used because of wide recognition. Estimation of ME intake in grazing cattle was expressed as MEVI = $14.58{\times}VI{\times}DMD$, and under grazing condition MEVI = $MER_i$. MER was expressed as a function of net energy(NER, MJ) required for the i'th body function. Coefficient of efficiency for conversion of ME into net energy(ki) was adopted from literatures. Quantifying of ME requirement for Kedah-Kelantan cattle under grazing condition was made by using equation MERM = NEM / kn. The estimated values of MER for Kedah-Kelantan cattle is quite reasonable if compared with other estimates as reported in literatures from stall-fed animals. Dynamic MER models for grazing herd was developed in order to estimate ME requirement for maintenance and productions. These ME requirement models can be used for prediction of energy utilization pattern of the herd in the grazing systems.

• 한국태양에너지학회:학술대회논문집
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• 한국태양에너지학회 2008년도 춘계학술발표대회 논문집
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• pp.342-347
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• 2008

A Microsoft $Access^{(R)}$ application that estimates hourly building energy load is developed based on statistical field measurements. Hourly patterns of heating, hot water, cooling, and electricity loads are evaluated for an energy consuming community composed of various types of buildings. Popular building types such as apartments, offices, hotels and accomodations, stores, churches, schools and educational institutes are included in the model. For each type of buildings, hourly patterns for a month are measured and compiled to derive a 24-hour load distributions. Daily sum of heating, hot water, cooling, and electricity loads are also measured for the building types. The annual energy need profiles are generated by combining the 24-hour distribution and 365-day consumption patterns. The annual maximum values of the 8760 hours of a year for each load type serves as a guide for selecting a device capacity. A user-friendly interface that ushers users throughout the whole process is provided.

• 한국유체기계학회 논문집
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• 제19권4호
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• pp.54-62
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• 2016

This study presents an approach of tidal farming optimization using a numerical modelling method to simulate tidal energy extraction for 1MW scale tidal stream devices around Jangjuk-sudo, South Korea. The utility of the approach in this research is demonstrated by optimizing the tidal farm in an idealized scenario and a more realistic case with three scenarios of 28-turbine centered tidal array (named A, B and C layouts) inside the Jangjuk-sudo. In addition, the numerical method also provides a pre-processing calculation helps the researchers to quickly determine where the best resource site is located when considering the position of the tidal stream turbine farm. From the simulation results, it is clearly seen that the net energy (or wake energy yield which includes the impacts of wake effects on power generation) extracted from the layout A is virtually equal to the estimates of speed-up energy yield (or the gross energy which is the sum of energy yield of each turbine without wake effects), up to 30.3 GWh/year.