• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.14 no.5
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• pp.450-457
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• 2003

In this paper, we studied the effect of asymmetrical 3rd order IMD of power amplifier due to changes in modulation frequency on IMD cancellation performance. The phase extraction method for determining asymmetric rate for phase distortion of IMD is proposed and the phase difference between lower and upper 3rd order IMD is measured by this method. The phase compensation circuit to decrease the phase difference is also designed and fabricated. From the measurement results using the phase compensation circuit applied to 5 W RF power amplifier fur PCS applications, the 3rd order IMD cancellation performance can be achieved up to 2-tone spacing 1.5 MHz (phase difference within 10$^{\circ}$).

• Transactions of the Korean Society of Mechanical Engineers A
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• v.20 no.6
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• pp.1872-1881
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• 1996

LBB(Leak-Before-Break) analysis is performed for the highest stress location of each different type of mateerials in the nuclear piping line. In most cases, the highest stress occurs in the pipe and nozzle interface location. i.e. terminal end. The current finite element analysis approach utilizes the symmetry condition both for locations near the nozzle and for locationa away from the nozzle to minimize the size of the finite element model and to make analysis simple when calculating the J-integral values at the crack tip. In other words, the nozzle is not included in the finite element model. However, in reality, the symmetric condition is not applicable for the pipe-nozzle interface location. Because the pipe-nozzle interface location is asymmetric due to different stiffenss of the pipe and nozzle(both material and dimensions). The simplified analysis approach for pipe-nozzle interface locaiton is too conservative for a smaller diameter piping. In tlhis paper, various analyses are performed for the range of materials and crack sizes to evaluate the nozzle effect for a LBB anlaysis. This paper presents methodology for developing the piping evaluaiton diagram at the pipe-nozzle interface location.

• Journal of Korean Institute of Industrial Engineers
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• v.23 no.3
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• pp.533-544
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• 1997

Among numerous factors that have an effect on visual field, the effects of background condition on the size of the visual field were investigated to obtain more practical visual field that can be readily applicable to industrial settings. A visual experiment was conducted, in which the subject was instructed to search a target with distinct orientations. Size contrast, meridian, nontarget density, and subject's gender showed a significant effect on the size of the visual field at $\alpha=0.01$. The size of the visual field was linearly proportional to size contrast, and inversely proportional to density. Female's visual fields were found to be significantly larger than male subjects', The size of the visual field on horizontal axis was larger than that on vertical axis, and the size of the head & eye field on right meridian was also larger than that on left meridian. The shape was found to be horizontally oriented oval and statistically asymmetric with respect to horizontal and vertical axes. The regression equations to predict the visual fields on the given background condition were suggested. The visual fields suggested in this study would be valuable to the design of visual displays and the panel layout of various displays and controls.

• International Journal of Quality Innovation
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• v.10 no.2
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• pp.109-126
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• 2009

The purpose of this study was to examine overall customer satisfaction associated with medical service quality in Taiwan by integrated Kano's model and customer satisfaction index model. Another purpose was to confirmed nonlinear and asymmetric relationship of Customer Satisfaction and Quality Performance by the research outcome. By analyzing 1,100 patients or their family members, this study used the structural equation model (SEM) with AMOS software for data analysis. The results show that must-be attributes, one-dimensional attributes and attractive attributes had a direct effect on overall customer satisfaction, Surprisingly, overall customer satisfaction had positively influenced customer loyalty customer satisfaction had negatively influenced customer complaints. The study also found that customer complaints have direct effect on customer loyalty. Importantly, the study found out the must-be attributes, the attractive attributes and one-dimensional attributes increased, the level of overall customer satisfaction also increased. The customer satisfaction positively influences customer loyalty in medical service quality in Taiwan. The findings might reveal new insights for researchers dealing with quality of medical service and for hospital managers who devote resources exclusively to achieving highest possible levels of patient satisfaction.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 1994.04a
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• pp.375-384
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• 1994

Depending upon the eye and head movement, the visual field is often classified into three categories; stationary field, eye field and head field. To investigate the effect of background condition on the size of stationary field, an experiment was conducted, in which the subject was instructed to search a target with distinct orientations. In each trial, a single target was presented on the rear-view screen projected by the two-field tachistoscope, with the visual angle subtended 4.3.deg. vertically and horizontally. Density, meridian and subject showed a significant effect on stationary field at .alpha.=0.01, where density was inversely proportional to the size of stationary field. The size of the stationary field on horizontal axis was larger than that on vertical axis, and that on right and below meridian also larger than on left and lower meridian. The shape was found to be horizontally oriented oval and statistically asymmetric with respect to horizontal and vertical axes. The regression equation to predict stationary field on the given background condition was suggested. These results were expected to be used as a designing guideline when arranging displays and controls on panels such as automobile display panels, cockpits, etc. In addition, it can be inferred from the results that eye field and head field are also subjected to the influence of background condition.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.26 no.6
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• pp.8-15
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• 2012

In this paper, we investigated possible optical parameters causing deviation of experimentally observed output spectra from theoretically predicted results in a high-order fiber comb filter based on a polarization-diversity loop configuration. They include wavelength dependency of half-wave plates (HWPs) inserted in the filter for wavelength switching and the modal birefringence of single-mode fibers (SMFs) with which optical components comprising the filter are connected. In order to consider the effect of the modal birefringence of the SMF on a filter performance, it is modeled as a low birefringence fiber with an arbitrary orientation angle and birefringence. It is found from the simulation results that the modal birefringence of SMFs strongly affects the spectral characteristics of the filter and decreases the extinction ratio of the filter, compared with the wavelength dependency of HWPs. In particular, it is also confirmed that the spectral deviation and asymmetric distortions of side-lobes in narrow band transmission spectra result mainly from the modal birefringence of SMFs.

• Journal of Powder Materials
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• v.6 no.4
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• pp.307-313
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• 1999

The effect of carbon content on the shape of WC grains dispersed in the Co-rich matrix during liquid phase sintering of WC-35%Co hard metals has been determined. The shape of WC grains was observed using SEM stereography after removing cobalt matrix with boiling hydrochloric acid solution. The WC grains changed from hexagonal to trigonal prism as the carbon content increased in the two-phase region of(WC + $\beta$ - Co), while the morphology of WC grains changed from trigonal to hexagonal shape as the carbon content decreased. The morphology of WC grains changes reversibly along with carbon loss or carbon pick-up. Morphology change of WC grains is attributed to crystal structure of WC, which has an asymmetric array of carbon atoms. There are two types of prismatic planes having different numbers of broken W-C bonds in WC grains. It is scrutinized that as the carbon content increases, the high energy prism planes grow fast and the crystals change from hexagonal to trigonal shape. On the other hand, when the carbon content decreases, the high energy prism planes are dissolved accompanying split of (100) plane into (101) and (101) planes.

• The Journal of Asian Finance, Economics and Business
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• v.7 no.3
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• pp.149-156
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• 2020

The study aims to investigate a close relation between macro and non-macro variables on stock performance of tourism companies in Korea. The sample used in this study includes monthly data from January 2001 to December 2018. The stock price index of the tourism companies as a dependent variable are obtained from Sejoong, HanaTour, and RedcapTour as three leading Korean tourism companies that have been listed on the Korea Stock Exchange. This study assesses the tourism stock performance using the quantile regression approach. This study also investigates whether global crisis events as the Iraq War and the global financial crisis as non-macro variables have a significant effect on the stock performance of tourism companies in Korea. The results show that the oil prices, exchange rate and industrial production have negative coefficients on stock prices of tourism companies, while the effects of tourist expenditure and consumer price index are positive and significant. We estimate the result of quantile regression that non-macro determinants have statistically a significant and negative effect on tourism stock performance because the global crisis could threaten traveler's safety and economy. Overall, empirical results suggest that the effects of macro and non-macro variables are statistically asymmetric and highly related to tourism stock performance.

• Structural Engineering and Mechanics
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• v.67 no.6
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• pp.671-682
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• 2018

The effect of earthquake induced torsion, due to mass eccentricities, is investigated with the objective of providing practical design guidelines for minimizing the torsional response of building structures. Current code provisions recommend performing three dimensional static or dynamic analyses, which involve shifting the centers of the floor masses from their nominal positions to what is called an accidental eccentricity. This procedure however may significantly increase the design cost of multistory buildings, due to the numerous possible spatial combinations of mass eccentricities and it is doubtful whether such a cost would be justifiable. This paper addresses this issue on a theoretical basis and investigates the torsional response of asymmetric multistory buildings in relation to their behavior when all floor masses lie on the same vertical line. This approach provides an insight on the overall seismic response of buildings and reveals how the torsional response of a structure is influenced by an arbitrary spatial combination of mass eccentricities. It also provides practical guidelines of how a structural configuration may be designed to sustain minor torsion, which is the main objective of any practicing engineer. A parametric study is presented on 9-story common building types having a mixed-type lateral load resisting system (frames, walls, coupled wall bents) and representative heightwise variations of accidental eccentricities.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.51 no.8
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• pp.413-424
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• 2002

Recently, in the linear motion system, high performances are required In dynamic characteristics. Vector control method is capable of instantaneous thrust control can meet these high performance requirements. Linear induction motor(LIM) have static and dynamic end effects due to its finite core length, so that per-phase impedances are asymmetric and an air gap flux distribution is distorted. These points of the d-q axis equivalent circuit model considering both end effects is more complicated. This paper proposes the d-q axis equivalent circuit and the vector control method considering both static and dynamic end effects of the LIM. As a result, it is shown that the results of the equivalent circuit method(ECM) have a good agreement with those of the finite element method(FEM).