• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제52권12호
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• pp.649-654
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• 2003

The simplest method for measuring output currents of the three phase inverters is to measure them with three current sensors such as hall sensors. This method requires at least two current sensors, and these types of sensors are somewhat expensive. More economical method is measuring DC link current with a simple shunt resistor, then, reconstructing output current using the DC link current value and the switching status. However, in low speed region, the measurement becomes difficult and even impossible due to the requirement of minimum switching duration for A/D conversion. These problems can be overcome by limitation of switching duration. Limitation of switching, however, causes voltage and current distortion. Owing to compensation, distortion can be effectively suppressed. However these increase acoustic noise due to increment of current ripple. In this paper, a current measurement method is proposed, which can reduce minimum switching duration resulting in reduction of acoustic noise. The validity of proposed method is confirmed through experiment.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2002년도 추계학술대회 논문집
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• pp.227-230
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• 2002

The switching device in an inductive circuit is stressed by the over-voltage at the turn-off time. Thus if the peak value of the over-voltage is not properly limited, the switching device may be broken. Therefore, the snubber circuit should be added to protect the switching device from the over-voltage. The circuit designer must be familiar with the design of the snubber This paper tests the possibility that TVS instead of the conventional snubber can be applied to the protection circuit of the switching device without using the complicated design equations, and shows that the rating of TVS can be easily selected by considering only several parameters of TVS. The experimental results show the reduced switching voltage of the switching device at the turn-off time.

• 한국정보시스템학회지:정보시스템연구
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• 제25권1호
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• pp.183-200
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• 2016

목적 많은 사용자들이 스마트폰을 바꾸고 있지만 대부분의 경우 새로운 스마트폰으로 바꾸는 대신 기존에 가지고 있는 스마트폰을 계속 사용하려는 경향이 있다. 브랜드 충성도와 전환비용은 기존의 스마트폰을 계속 사용하는 경향을 결정하는 요인이다. 다음과 같은 연구문제를 제기한다. "새로운 스마트폰을 구매하는데 있어서 브랜드 충성도와 전환비용의 역할은 무엇인가?" 방법론 기존 브랜드를 계속 사용하려는 경향을 고려하여 새로운 스마트폰 구매의도를 설명하기 위한 여섯 개의 가설을 제안했다. 연구모형은 177명의 대학생을 대상으로 LG의 G4 스마트폰을 구매의도에 대해 실증적 검증을 하였다. PLS에 의해 자료 분석을 한 결과 모든 가설이 통계적으로 지지받았다. 결과 첫째, 기존 스마트폰에 대한 브랜드 충성도와 전환비용은 새로운 스마트폰 구매에 영향을 미친다. 둘째, 브랜드 충성도는 전환비용과 상대적 이점의 관계에서 조절변수 역할을 한다. 셋째, 지각된 심미성과 가격 가치도 스마트폰 구매에 영향을 미친다.

• Journal of Positioning, Navigation, and Timing
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• 제8권3호
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• pp.95-105
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• 2019

A method that applies space-time adaptive signal processing (STAP) algorithm based on an array antenna consisting of multiple antenna elements has been known to be effective to remove wide-band jamming signals in GPS receivers. However, the occurrence of phase distortion in navigation signals has been a problem when navigation signals, from which jamming signals are removed using STAP, are supplied to global positioning system (GPS) receivers. This paper verified the navigation performance degradation as a result of phase distortion. To mitigate this phenomenon, this paper proposes a mode switching scheme, in which a bypass mode is adopted to make the best use of the tracking performance of receivers without performing signal processing when jamming signals are not present or weak, and a STAP mode is employed when jamming signals exceed the threshold value. In this paper, the mode switching scheme is proposed for two environments: when receivers are stationary, and when receivers are moving. This paper confirmed that the performance of position error improved because phase distortion could be excluded due to STAP if the bypass mode was adopted under a condition where the jamming signal power level was below the threshold value in an environment where receivers were stationary. However, this paper also observed that the navigation failed due to the instability of tracking performance of receivers due to phase distortion that occurred at the switching time, although the number of switching could be reduced dramatically by proposing a dual threshold scheme of on- and off-thresholds that switched a mode due to the array antenna characteristics of varying gains according to the jamming signal incident direction in an environment where receivers were moving. The analysis results verified that running the STAP algorithm at all times is more efficient than the mode switching, in terms of maintaining stable navigation and ensuring position error performance, to remove jamming signals in an environment where receivers were moving.

• 한국의류학회지
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• 제35권4호
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• pp.408-420
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• 2011

This study identifies the fashion luxury customer segments grouped by expenditures and the number of purchasing brands to verify the effects of perceived luxury consumption values on the intention to maintain a brand relationship for each group. A survey questionnaire was developed and implemented to collect data to measure fashion luxury expenditures, number of purchasing brands, luxury customer values, intention to maintain brand relationships, and demographic variables. A total of 326 responses were analyzed by factor analysis, multiple regression, one-way ANOVA, and $X^2$ analysis with SPSS18.0. Respondents were grouped by luxury expenditures; in addition, the number of purchasing brands were grouped into four segments of Switching/Heavy (31.6%), Switching/Light (19.9%), Loyal/Heavy (31.3%), and Loyal/Light (7.2%) Customer Group, that was different in terms of age and marital status. When the luxury customer value for the most patronized luxury brand was factor analyzed, five distinctive sub dimensions were identified, such as Social Value, Aesthetic/Expressive Value, Experiential Value, Quality Value, and Economic Value. For the Loyal/Heavy Group, the Experiential Value had a significant effect on the customer intention to maintain a brand relationship. For the Loyal/Light group, the Aesthetic /Expressive and Economic Value had a significant effect, and for the Switching/Heavy and Switching/Light Group, Quality and Economic Value had a significant effect on the customer intention to maintain a brand relationship. In conclusion, each luxury customer value in the behavioral segments works differently in influencing the intention to maintain a brand relationship. In addition, the implications for retail strategy were discussed based on the findings.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2003년도 하계종합학술대회 논문집 V
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• pp.2863-2866
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• 2003

In nonlinear control fields, for irregular nonlinear systems, control form which consists of approximate tracking control law and exact tracking control law and which switches between two laws has been proposed recently. In this thesis, we design new switching control law which connect approximate linearization control law and exact linearization control law by fuzzy rules for irregular nonlinear system, ball and beam system. Fuzzy switching controller designed by fuzzy concept is proved that designed scheme overcomes singularities of irregular system, improves unstability problem of switching procedure, and has more efficient control value through simulation. Stability of fuzzy control system proved by Lyapunov's stability theorems.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 1999년도 추계종합학술대회 논문집
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• pp.743-746
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• 1999

In this paper, Flyback type DC/DC Switching Converter was designed, analyzed and fabricated. Worst Case Analysis(WCA) was peformed with Mathcad program and presents circuit simulation results for the in-rush current limit circuit. The value of the maximum OFF voltage stress is 131.84V, it is less than device specification(200V). The switching frequency(nominal case) and duty cycle at the wont case analysis are 75KHz and 34.62%, respectively. The maximum in-rush current presents 0.5A Those results show a possibility for use in space

• Journal of Power Electronics
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• 제9권4호
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• pp.623-630
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• 2009

This paper proposes a filter design guideline for grid-connected single-phase inverters. By analyzing the instantaneous voltage applied to the filter inductor, the switching ripple current through the filter inductor can be precisely calculated. Therefore, filter inductance can be designed accurately, which guaranties that the switching ripple current will be under the target value. The proposed filter design method is verified by experiment.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2007년도 7th International Meeting on Information Display 제7권1호
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• pp.560-563
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• 2007

The light efficiency of fringe-field switching (FFS) mode was found to be dependent on the magnitude of dielectric anisotropy, indicating that the voltagedependent maximal effective cell retardation value in the on state is a function of magnitude of the dielectric anisotropy of the LC.

• 대한전기학회논문지
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• 제43권7호
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• pp.1050-1060
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• 1994

This paper is a study on the computer simulation of the characteristics of the superconducting fault current limiter. Input variable parameters are apparent power, load resistance value, line resistance value and so on. Initial fault current 2 times larger than the trigger current is required to reduce the switching time of SFCL. The propagation velocity increases abruptly, the transport current is several times larger than the ciritical current. In this paper, the switching time is calculated to be 323$\mu$ sec, and the initial fault current is 19 times larger than the critical current. Because the trigger coils are bifilar winding, they have little impedance in superconducting state. After fault occurred, the limiting coil acts as a superconducting reactor and the trigger coils quench at a critical current. Without the SFCL in the circuit, fault current after the load impedence is shorted might be increased to 1100A. The fault current is, therefore, successfully limited by the superconducting limiting coil to 100A determined by the coil inductance.