• Journal of Power Electronics
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• 제16권1호
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• pp.238-248
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• 2016

The state-of-charge (SOC) and state-of-health (SOH) estimation of batteries play important roles in managing batteries for automotive applications. However, an accurate state estimation of a battery is difficult to achieve because of certain factors, such as measurement noise, highly nonlinear characteristics, strong hysteresis phenomenon, and diffusion effect of batteries. In certain vehicular applications, such as idle stop-start systems (ISSs), significant errors in SOC/SOH estimation may lead to a failure in restarting a combustion engine after the shut-off period of the engine when the vehicle is at rest, such as at a traffic light. In this paper, a dual extended Kalman filter algorithm with a dynamic equivalent circuit model of a lead-acid battery is proposed to deal with this problem. The proposed algorithm adopts a battery model by taking into account the hysteresis phenomenon, diffusion effect, and parameter variations for accurate state estimations of the battery. The validity of the proposed algorithm is verified through experiments by using an absorbed glass mat valve-regulated lead-acid battery and a battery sensor cable for commercial ISS vehicles.

• Nuclear Engineering and Technology
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• 제56권8호
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• pp.2916-2922
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• 2024

\\In memory semiconductors such as a static random access memory (SRAM), a common problem is soft errors under radiation environment. These soft errors cause bit flips, which are referred to as single event upsets (SEUs). Some radiation-hardened SRAM cells such as a Quatro SRAM, we-Quatro SRAM, and DICE SRAM cells have been reported for years. However, these designs have the disadvantage of taking up more area than a conventional 6T SRAM cell. Thus, we propose a radiation-hardened SRAM cell design that we named capacitor-static random access memory (C-SRAM) without area overhead. The C-SRAM is formed by simply adding a capacitor to the conventional 6T SRAM. It was designed to mitigate the radiation effect using the conservation law of electrical charge. Moreover, it has the same cell size as the conventional 6T SRAM cell. Its static noise margins (SNMs), which are indicators of operational stability, are equal to the conventional 6T SRAM values of 530 mV, 220 mV, and 860 mV in hold, read, and write modes, respectively. The results of the SEU simulation test showed that it had 4.761 times better flipping tolerance than the conventional 6T SRAM with a charge value of 247.494 fC. In addition, irradiation experiments also confirmed that the C-SRAM cell was more tolerant than the 6T SRAM cell. The conventional 6T SRAM and C-SRAM were fabricated using a standard 0.18 ㎛ CMOS process.

• 대한방사선기술학회지:방사선기술과학
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• 제9권1호
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• pp.51-63
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• 1986

We got the following results from the 324 radiologic technologists as we surveyed their working condition by using the questionaire, who were working in the medical institutions (general hospitals and doctor's clinics) situated in the area of Seoul city, Kyung ki-do and Chung-chong-do since June to December 1985. 1. Their daily average working time was almost within 10 hours (in 93.9% of general hospitals, 66.1% of clinics). 2. About the numbers of holidays, 85.5% of general hospitals have one holiday per week,41.3% of clinics have one holiday per week or 38.5% of clinics have one holiday per two weeks. 3. Duty appointment of radiologic technologists in the department of radiology is taking charge of each part after serving for a certain part for some period (42.8%), taking charge of the special part continually or by turns in other working parts (35.3%). On the other hand in the clinics they took charge of all parts continually (53.2%) or by turns with their own situations. (30.3%). 4. Their daily working amount is too much in 51.6% of general hospitals or 45.8% of clinics. 5. They answered it was hard in 81.4% of general hospitals or 43.1% of clinics about the degree of difficulty of their work. 6. Their monthly salary is higher in the clinics than in the general hospitals and higher in Seoul area than in Kyung-ki or Chung-chong area. 7. Their yearly bonus .ate is 400%-600% (69.2%) in almost general hospitals, 100%-300% (57.8%) in th. clinics. 8. Danger allowance is paid with the monthly salary in 62.8% of the general hospitals or 19.2% of clinics and license allowance is paid in 44.7% of general hospitals or in 12.8% of clinics. 9. Their initial salary (except bonus) is about 200,000 won (in 76.8% of general hospitals, in 67.8% of clinics). 10. Their salary is raised regulary every year in 52.6% of general hospitals, but it is irregulary in 73.4% of clinics. 11. Promotion system is managed in 48.4% of the general hospitals or in 14.7% of clinics. 12. Retirement allowance is assured in 96.9% of the general hospitals or in 63.3% of clinics. 13. Main cause of their retirement is moving to more paid hospitals, better hospitals in working condition or facilities, moving to another cities, to the hospitals with more opportunities of promotion or choosing other jobs etc. 14. Human relationship with doctors, nurses or co-worker technologists as a member of medical team appeared almost intimate and good.

• 한국진공학회:학술대회논문집
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• 한국진공학회 1994년도 제6회 학술발표회 논문개요집
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• pp.50-50
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• 1994

Half-metallic Heusler alloys (NiMnSb, ppdMnSb, pptMnSb) have attracted much attention due to their unique electronic and magnetic structures. Sppin-ppolarized band structure calculation ppredicts metallic behavior for the majority sppin states and semiconductor behavior for the minority sppin states. We have studied the electronic structures of these half-metallic Heusler alloys by core-level pphotoemission sppectroscoppy of Mn 2pp and 3s XppS sppectra. We found large intensities of Mn 2pp satellites and 3s exchange spplitting comppared with other metal Mn-alloys. These satellite structure can be understood by applying Anderson imppurity model. This fact supports the calculated sppin pprojected ppartial density of states which suggests that the valence electrons be highly sppin ppolarized near Fermi level and that the electrons involved with charge-transfer be mainly minority sppin ones which have semiconducting band structure. The trend of charge transfer energies Δ from ligands (Sb 5pp) to Mn 3d, obtained from our model fitting, is consistent with that calculated from sppin pprojected ppartial density of state. Also the trend of d-d electron correlation energies U calculated from Mn Auger line L3 VV by Mg $K\alpha$ source is comppatible with that resulted from our model fitting. We fitted the Mn 3s curve in the same way as for insulating Mn comppounds by using the same pparameters calculated from Mn 2pp curve fitting exceppt for the Coulomb interaction energy Q between core hole and d-electrons. The 3s sppectra were analyzed by combing the charge transfer model and a simpple model taking into account the configuration mixing effect due to the intra-shell correlation. We found that the exchange interaction between 3s hole and 3d electrons is mainly respponsible for the satellite of Mn 3s sppectra. This is consistent with the neutron scattering data, which suggests local 3d magnetic moment. We find that the XppS analysis results of Mn 2pp and 3s satellite structures of half-metallic Heusler alloys are very similar to those of insulating transition metal comppounds.

• 한국토양비료학회지
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• 제14권3호
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• pp.110-116
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• 1981

동일한 화산회로부터 발달한 세개의 하와이 토양을 사용하여 중요한 토양 물리화학적 성질을 결정하는 인자인 토양표면전하 (soil surface charge)의 특성에 대한 조사를 수행하였다. 높은 강우량(년 3050mm 이상)하에서 발달한 두 Typic Hydrandepts 토양은 pH 변화에 따른 음 양 전하의 발달이 대단히 컸으며 등전점은 각각 Akaka 토양이 5.0-5.5 사이, Hilo 토양이 6.5-7.0 사이에 있었다. 한편 낮은 강우량(년 500mm 이하)하에서 발달한 Ustolic Camorthid 토양은 pH 변화에 따른 음 양전하의 발달이 위 두 토양에 비하여 훨씬 낮았으며, 등전점 역시 4.5-5.0 사이로서 낮았다. 따라서 자연조건에서 Kawaihae 토양만이 -(음)의 ${\Delta}pH$를 나타내고 Akaka와 Hilo 토양은 +(양) 내지 0 근처의 ${\Delta}pH$ 값을 보여 주고 있다. X-ray 회절분석에 의하여 Typic Hydrandepts 토양의 주광물은 무정형 광물 (60 % 이상)이었고, Ustollic Camorthid 토양중의 주광물은 dehydrated halloysite(1:1 점토광물) (45-50 %)이었음이 밝혀졌다. 이같은 동일한 화산회에서부터 발달한 토양의 현저한 광물학적 차이는 토양발달과정중의 강우량 차이에서 기인한 것으로 추정된마, 세토양중의 점토함량은 최저 42% (Akaka 토양)와 최고 57% (Hilo 토양)로 그 차이가 크지 않았으나 이들 토양의 표면적 ($m^2/g$)은 289 (Akaka 토양), 268 (Hilo 토양) 그리고 93 (Kawaihae 토양)으로서 특별히 Kawaihae 토양이 현저히 낮았다. 이같은 토양간의 표면적과 전하적 특성의 현저한 차이는 토양중의 광물학적 차이에서 오는 것이며 1:1 광물이 주를 이루는 우리나라 대부분의 토양은 본 연구 중의 Kawaihae 토양과 유사한 특성을, 그리고 우리나라 제주도 화산회토의 일부는 Akaka나 Hilo 토양의 특성을 따를 것으로 예상되는 바이다.

• Journal of Information Technology Applications and Management
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• 제19권1호
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• pp.47-59
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• 2012

A number of organizations have had big interests in studies concerning leadership and in academic areas, in not only management but also psychology. Until now, leadership has been accentuated by managers or team leaders especially. Recently, however, the concept of self-leadership directing one's own activities through self-control or self-management is being focused on in practices and in academia. This study is to investigate the influence between self-leadership strategies and learning performance in IT classes mediated by attitude of attendance focused on the social science students in two universities (Korea (121 samples) and India (106 samples)). And this research tried to compare difference between two university students. Research results can give us direction of task-taking attitudes in firms or learning attitudes in teaching organizations and implications to human resource managers who are in charge of improving learning performance or productivity.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2011년도 정기총회 및 추계학술대회 논문집
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• pp.754-760
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• 2011

In the DC traction system, a large load current of electric railcar leads to a voltage drop when a vehicle starts, and the regenerative power generated by brake system increases the catenary voltage. To minimize the voltage fluctuation during the train operation and make use of the regenerative power, several types of energy storage systems are being studied. The energy storage system that is being recently introduced consists of the supercapacitors for energy storage and the bi-direction DC/DC converter for charge/discharge control. The efficiency of the energy storage system depends on the train operation pattern. In this paper, the operation efficiency of the energy storage system was quantitatively analyzed via simulation study taking consideration of the train operation patterns. The simulation was conducted changing the headway of trains with the energy storage system that uses the bi-direction DC/DC converter and supercapacitor. The simulation results showed that the operation efficiency of the energy storage system increases as the headway increase.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2001년도 Proceedings ICPE 01 2001 International Conference on Power Electronics
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• pp.785-789
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• 2001

Piezoelectric actuators are characterized by non-linear dynamics and high frequency oscillations of the piezocrystal. Both properties have to be taken into consideration when optimizing real time systems. Taking benefit of the almost linear behaviour between charge and strain, current source fed piezoelectric actuators are given preference for high dynamic applications. Here special emphasis is put on current sources for multi-actuator systems and the controller design for optimal system integration of the actuator. It is shown that sliding mode operation of the converter system offers good possibilities to guaranty high accuracy and dynamics of the actuators system. The presented multi-actuator system is used for positioning and vibration damping in flexible mechanical systems.

• 한국항해학회지
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• 제18권1호
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• pp.31-39
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• 1994

The practical shiphandlers, such as ship's captain, pilot and mooring master, in charge of the SBM app-roaches and mooring operations of loaded VLCC should have a highly advanced shiphandling skills because of taking advantage of the wind and current from ahead without assistance of big tugboats. But now except some approaching skills in the vicinity of SBM buoy or waiting anchorage we do not have an optimal controlled approaching maneuvers in the entire course of port approaches. Consequently this study presents the optimal SBM approaches to the practical shiphandlers of VLCC and puts to use with effect in the practical operations. The conclusions of this simulation study are as follows : 1) The optimal SBM approaches in combination of Woo's Approach and a large change of heading were presented for the practical shiphandlers, 2) According to simulation of the pilotship the angle of a large change of heading for reducing headway is more than 70 degrees approximately. 3) Applied this optimal approaches to the SBM operations of simulated Port of Ulsan and confirmed the control of ship and the economy of port approaches time.

• 품질경영학회지
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• 제31권2호
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• pp.1-16
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• 2003

The purpose of this research is to examine the influence of after sales service quality in the Korean home appliance. This study is assumed that after sales service quality is composed of prices of service and corporate image as well as technical quality and functional quality. Also, this study examined that how after sales service quality have influence on the repurchase and word-of-mouth effect, and the relationship between the repurchase and word-of-mouth effect was identified in this research. To perform the empirical study, 204 questionnaires from persons who experience taking after sales services with charge for their home appliance are gathered and analyzed. The results make contribution to the Korean home appliance manufacturing company to newly recognize about the factors of after sales services quality. Further empirical or theoretical study for finding the factors of after sales services quality can be recommended in the presence of competitive service industry.