• 대한전기학회:학술대회논문집
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• 대한전기학회 1994년도 하계학술대회 논문집 A
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• pp.310-312
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• 1994

A partial shunt regulator (PSR) which is the power regulator of KOREASAT is modeled. The modeling of the PSR consist of solar array, power circuit, controller. and load models. To realize simple structure. a voltage source of the PSR controller is used the output voltage of the PSR. The model of the PSR has very complex structure with two additional coupled feedback loops. The complex model is simplified to a simple meaningful model with only main feedback control loop. The proposed model is compared to a PSR model with DC voltage source at the PSR controller. The proposed PSR model is verified by comparing the model with SPICE simulation for small signal analysis.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1996년도 한국자동제어학술회의논문집(국내학술편); 포항공과대학교, 포항; 24-26 Oct. 1996
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• pp.808-811
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• 1996

A mathematical model was developed for the simulation of a Pressure Swing Adsorption process with dehydrogenation reaction. The minimum number of beds and optimum operating sequence were determined using MINLP under the given operating conditions. Based on these results, we estimated the minimum annual cost.

• Journal of Mechanical Science and Technology
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• 제15권1호
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• pp.88-97
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• 2001

The present study numerically investigates the fuel-air mixing characteristics, flame structure, and pollutant emission inside a double-swirler combustor. A PSR(Perfectly Stirred Reactor) based microstructural model is employed to account for the effects of finite rate chemistry on the flame structure and NO formation. The turbulent combustion model is extended to nonadiabatic flame condition with radiation by introducing an enthalpy variable, and the radiative heat loss is calculated by a local, geometry-independent model. The effects of turbulent fluctuation are taken into account by the joint assumed PDFs. Numerical model is based on the non-orthogonal body-fitted coordinate system and the pressure/velocity coupling is handled by PISO algorithm in context with the finite volume formulation. The present PSR-based turbulent combustion model has been applied to analyze the highly intense turbulent nonpremixed flame field in the double swirler combustor. The detailed discussions were made for the flow structure, combustion effects on flow structure, flame structure, and emission characteristics in the highly intense turbulent swirling flame of the double swirler burner.

• ETRI Journal
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• 제41권1호
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• pp.124-132
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• 2019

The energy balance (EB) model of a primary side regulation (PSR) fly-back converter in the discontinuous conduction mode (DCM) is discussed in this paper. Based on this EB model, the stability of a PSR fly-back converter in the pulse skipping mode (PSM) is analyzed, and a self-adapting modulation factor control strategy is proposed. Theoretical analysis and simulation results show that by saving an optocoupler and correlative circuits, which are necessary in traditional PSM fly-back converters, the modulation factor tolerance controlled by this method is 1.26% on average, corresponding to the ideal value. Compared with traditional fly-back PSM controllers, the power saved in the sampler/comparator modules is 87% on average for a load range of $1{\Omega}$ to $1k{\Omega}$.

• 한국전자파학회논문지
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• 제26권1호
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• pp.71-80
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• 2015

한정된 배터리 용량으로 장시간 모바일 시스템을 구동시키기 위하여 저전력 설계에 대한 요구가 높아지면서 PMIC(Power Management IC)의 핵심 부분인 LDO(Low Drop-Out) 레귤레이터의 설계에 대한 관심이 증가하고 있다. 본 논문에서는 Dongbu HiTek $0.5{\mu}m$ BCDMOS 공정을 이용하여 최적화 기법 중 하나인 기하 프로그래밍(Geometric Programming: GP)을 통해 외부 커패시터가 없는 LDO 레귤레이터의 성능을 최적화하였다. 계수가 양수인 단항식 (monomial)으로 모델링된 트랜지스터의 특성 파라미터들을 이용하여 안정도(stability)와 PSR(Power-Supply Rejection)과 같은 LDO 레귤레이터의 특성을 기하 프로그래밍(Geometric Programming: GP)에 적용 가능한 형태로 유도하였다. 위상 마진(phase margin)과 PSR 모델은 시뮬레이션 결과와 비교하였을 때 각각 평균 9.3 %와 13.1 %의 오차를 보였다. 제안한 모델을 사용하여 PSR 제약 조건이 바뀔 경우, 자동화된 회로 설계를 수행하였고, 모델의 정확도를 검증하였다. 본 논문에서 유도된 안정도와 PSR 모델을 이용하면 회로의 목표 성능이 변화하더라도 부가적인 설계 시간을 줄이면서 목표 성능을 가진 회로를 재설계하는 것이 가능할 것이다.

• 천문학회보
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• 제40권1호
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• pp.88.4-89
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• 2015

The Double Pulsar (PSR J0737-3039) is the only neutron star-neutron star (NS-NS) binary in which both NSs have been detectable as radio pulsars. The Double Pulsar has been assumed to dominate the Galactic NS-NS binary merger rate $R_g$ among all known systems, solely based on the properties of the first-born, recycled pulsar (PSR J0737-3039A, or A) with an assumption for the beaming correction factor of 6. In this work, we carefully correct observational biases for the second-born, non-recycled pulsar (PSR J0737-0737B, or B) and estimate the contribution from the Double Pulsar on $R_g$ using constraints available from both A and B. Observational constraints from the B pulsar favour a small beaming correction factor for A (~2), which is consistent with a bipolar model. Considering known NS-NS binaries with the best observational constraints, including both A and B, we obtain $R_g=21_{-14}{^+28}$ per Myr at 95 per cent confidence from our reference model. We expect the detection rate of gravitational waves from NS-NS inspirals for the advanced ground-based gravitational-wave detectors is to be $8_{-5}{^+10}$ per yr at 95 per cent confidence. We discuss prospects of gravitational-wave detection based on our results. Implications of PSR J1906+0746, which is likely to be another tight NS-NS binary in the Galactic disc supported by recent observation, are also remarked.

• 한국자동차공학회논문집
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• 제17권5호
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• pp.46-52
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• 2009

In this study the predictions of NOx in methane-air lean premixed combustion in PSR were carried out with GRI 3.0 methane-air combustion mechanism and Zeldovich, nitrous oxide, prompt, and NNH NO formation mechanism by using CHEMKIN code. The results are compared to the JSR experimental data of Rutar for the validation of the model. This study concerns about the importance of the chemical pathways. The chemical pathway most likely to form the NO in methane-air lean-premixed combustion was investigated. The results obtained with the 4 different NO mechanisms for residence time(0.5-1.6ms) and pressure(3, 4.7, 6.5 atm) are compared and discussed.

• 경영과학
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• 제28권3호
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• pp.61-72
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• 2011

This study suggests a DEA(Data Envelopment Analysis) based model to evaluate the value of corporate stock. The model integrating PER(Price-Earning Ratio), PBR(Price-BookValue Ratio), PSR(Price-Sales Ratio) and volatility in DEA structure has an advantage of overcome the limitation of traditional financial ratio based models. In order to show the effectiveness of the suggested model. we compare the performance of portfolio composed by DEA approach with those of portfolios made by traditional approaches such as PER, PBR, and PSR in terms of stock return and volatility. Specifically, we use the data of all the enterprises listed on the S&P 500 in the U.S. in 2007 and 2009 as the sample data for the experiments. The results of the experiments show that the performance of the DEA approach is clearly better than those of other approaches. Particularly, in sharply plummeting market, the performance of the DEA approach is shown to be prominently better than those of other approaches as the DEA approach reflects investment risk as well as profitability and growth. The DEA score combining the existing investment indices may serve as a useful barometer for selecting a stable and profitable portfolio.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제13권10호
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• pp.5035-5057
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• 2019

Advancements in nanotechnology and novel nano materials in the past decade have provided a set of tools that can be used to design and manufacture integrated nano devices, which are capable of performing sensing, computing, data storing and actuation. In this paper, we have proposed cooperative nano communication using Power Switching Relay (PSR) Wireless Power Transfer (WPT) protocol and Time Switching Relay (TSR) WPT protocol over independent identically distributed (i.i.d.) Rayleigh fading channels in the Terahertz (THz) Gap frequency band to increase the range of transmission. Outage Probability (OP) performances for the proposed cooperative nano communication networks have been evaluated for the following scenarios: A) A single decode-and-forward (DF) relay for PSR protocol and TSR protocol, B) DF multi-relay network with best relay selection (BRS) for PSR protocol and TSR protocol, and C) DF multi-relay network with multiple DF hops with BRS for PSR protocol and TSR protocol. The results have shown that the transmission distance can be improved significantly by employing DF relays with WPT. They have also shown that by increasing the number of hops in a relay the OP performance is only marginally degraded. The analytical results have been verified by Monte-Carlo simulations.

• 천문학회지
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• 제54권1호
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• pp.1-8
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• 2021

We report X-ray timing and spectral properties of the pulsar PSR J0205+6449 measured using NuSTAR and Chandra observatories. We measure the pulsar's rotation frequency ν = 15.20102357(9) s-1 and its derivative $\dot{\nu}=-4.5(1){\times}10^{-11}\;s^{-2}$ during the observation period, and model the 2-30 keV on-pulse spectrum of the pulsar with a power law having a photon index Γpsr = 1.07 ± 0.16 and a 2-30 keV flux F2-30 keV = 7.3±0.6 × 10-13 erg cm-2 s-1. The Chandra 0.5-10 keV data are analyzed for an investigation of the pulsar's thermal emission properties. We use thermal and non-thermal emission models to fit the Chandra spectra and infer the surface temperature T∞ and luminosity Lth of the neutron star to be T∞ = 0.5 - 0.8 MK and Lth = 1 - 5 × 1032 erg s-1. This agrees with previous results which indicated that PSR J0205+6449 has a low surface temperature and luminosity for its age of 800-5600 yrs.