• Journal of Power Electronics
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• 제10권6호
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• pp.749-761
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• 2010

The switching frequency of a power device is a very important parameter in the design of a parallel active power filter (PAPF), but so far, very little discussion has been conducted on it in a quantitative manner in previous publications. In this paper, an extensive analysis on the effects of the switching frequency on the performance of a PAPF is made, and a specification of the switching frequency values with different compensation results is presented. A first-order inertia element and a second-order oscillation element are considered as approximate models of a PAPF, respectively. The compensation characteristic for each order of harmonic current is obtained at different switching frequencies. Then, the THDs of each model for the system loads of a rectifier with resistance and inductance loads are proposed. The compensation results of a PAPF controlled as a first-order inertia element are better than those of a PAPF controlled as a second-order oscillation element. With two types of system loads which are rectifier with resistance and inductance loads and rectifier with resistance, inductance and capacitance loads, the THDs of the source current after compensation are presented with different switching frequencies. The compensation characteristics for the most widely used digital control system are investigated. The situation with an analog control is the theoretical characteristic and it is the best situation. The compensation characteristic of the digital control is worse than the compensation characteristic of the theoretical characteristic. Based on these analyses, the specifications of compensation characteristics with different switching frequencies are quite straightforward. Finally, a practical design example is studied to verify the application.

• 한국측량학회지
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• 제35권5호
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• pp.365-374
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• 2017

SAR (Synthetic Aperture Radar) is an effective tool for monitoring areas damaged by disasters. Full PolSAR (Polarimetric SAR) enhances SAR's capabilities by providing specific scattering mechanisms. Thus, full PolSAR data have been widely used to analyze the situation when disasters occur. To interpret full PolSAR data, model-based decomposition methods are frequently used due to its easy physical interpretation of PolSAR data and computational efficiency. However, these methods present problems. One of the key problems is the overestimation of the volume scattering component. To minimize the volume scattering component, the OA (Orientation Angle) compensation method is widely utilized. This paper shows that the effect of the OA compensation was analyzed over landslide affected areas. In this paper, the OA compensation is applied by using the OA estimated from the maximum relative Hellinger distance. We conducted an experiment using two full polarimetric ALOS/PALSAR (Advanced Land Observing Satellite/Phased Array type L-band Synthetic Aperture Radar)-2 data collected over Mocoa, Colombia which was seriously damaged by the 2017 Mocoa landslide. After OA compensation, the experimental results showed volume scattering power decreased, while the double-bounce and surface scattering power increased. Particularly, significant changes were noted in urban areas. In addition, after OA compensation, the separability of the double-bounce and surface scattering components are improved over the damaged building areas. Furthermore, changes in the OA can discriminate visually between the damaged building areas and undamaged areas. In conclusion, we demonstrated that the effect of OA compensation improved the influence of the double-bounce and surface scattering components, and OA changes can be useful for detecting damaged building areas.

• Geomechanics and Engineering
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• 제20권4호
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• pp.313-322
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• 2020

This study focuses on a prediction approach of compaction compensation grouting efficiency in sandy soil. Based on Darcy's law, assuming that the grouting volume is equal to the volume of the compressed soil, a two-dimensional calculation model of the compaction compensation grouting efficiency was improved to three-dimensional, which established a dynamic relationship between the radius of the grout body and the grouting time. The effectiveness of this approach was verified by finite element analysis. The calculation results show that the grouting efficiency decreases with time and tends to be stable. Meanwhile, it also indicates that the decrease of grouting efficiency mainly occurs in the process of grouting and will continue to decline in a short time after the completion of grouting. The prediction three-dimensional model proposed in this paper effectively complements the dynamic relationship between grouting compaction radius and grouting time, which can more accurately evaluate the grouting efficiency. It is practically significant to ensure construction safety, control grouting process, and reduce the settlement induced by tunnel excavation.

• 디지털융복합연구
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• 제11권10호
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• pp.153-168
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• 2013

정보보안은 여전히 많은 조직에서 해결해야할 중요한 문제 중 하나이다. 특히 어떻게 조직 구성원들의 보안행위를 유도할 것이며, 내부인력에 의한 사고를 줄일 수 있는지는 여전히 정보보안 분야에서 탐색되어야할 문제로 남아있다. 본 연구는 선행연구에서 제시한 정보보안 대책이 상황에 따라 다른 결과를 나타나는 이유를 설명하고자 한다. 이를 위해 위험보상 이론을 기반으로 연구모형을 수립하고 실증적으로 분석하였다. 분석 결과 정보보안 대책과 조직 구성원들의 보안정책준수의도 간의 관계는 시스템의 취약성에 의해 조절되는 것으로 나타났다. 본 결과는 위험보상이론의 기본 가정과 반대된다. 반면 시스템 품질의 조절효과는 없는 것으로 나타났다.

• Journal of Advanced Marine Engineering and Technology
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• 제27권4호
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• pp.503-510
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• 2003

A new method of induction motor drive, which requires neither shaft encoder nor speed estimator, is presented. The proposed scheme is based on decreasing current gap between a numerical model and an actual motor. By supplying the identical instantaneous voltage to both model and motor in the direction of reducing the current difference. the rotor approaches to the model speed. that is. reference value. The indirect field orientation algorithm is employed for tracking the model currents. The performance of induction motor drives without speed sensor is generally characteristic of poorness at very low speed. However, in this system, it is possible to obtain good speed response in the extreme low speed range.

• 한국경영과학회지
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• 제31권3호
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• pp.27-40
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• 2006

Today's customer demands in supply chains tend to change quickly, variously even in a short time Interval. The uncertainties of customer demands make it difficult for supply chains to achieve efficient inventory replenishment, resulting in loosing sales opportunity or keeping excessive chain wide inventories. Un this paper, we propose an adaptive vendor managed inventory (VMI) model for a two-echelon supply chain with non-stationary customer demands using the action-reward learning method. The Purpose of this model is to decrease the inventory cost adaptively. The control Parameter, a compensation factor, is designed to adaptively change as customer demand pattern changes. A simulation-based experiment was performed to compare the performance of the adaptive VMI model.

• The Journal of Asian Finance, Economics and Business
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• 제6권3호
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• pp.91-101
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• 2019

This paper finds some stylized facts about executive pay in South Korea. Using aggregate data of the listed companies since 2002, we find that 1) the director's remuneration has risen faster than the employee compensation, thus, the pay ratio of executive and employee has escalated from 3.0 to 4.5; 2) the executive compensation for large business group fluctuates more widely than that for small and medium enterprises does, hence the pay ratio for large firms changes widely too; 3) the median pay ratio has not grown monotonically but it rather rises to remain still around year 2011, which is accounted for mostly by small and medium enterprises. New information on executive compensation by compulsory disclosure starting from 2013 made further analysis of CEO compensation attainable. Based on the conventional regression analysis for 2013-2017, we find that 1) the elasticity of CEO pay with respect to firm value is about 0.18; 2) the volatility of stock return is negatively related to CEO pay; 3) contemporaneous stock return is positively associated with the pay; 4) there is insufficient evidence that large business groups pay their CEOs more than small and medium enterprises do. These results are robust under various model specifications.

• The Journal of Asian Finance, Economics and Business
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• 제7권10호
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• pp.999-1006
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• 2020

This study provides an understanding of the role of job satisfaction as a mediator of compensation and workplace environments for the organizational commitment of employees in the public sector. This study used a structural model using path analysis. The population and sample in this study were all employees at the Population and Civil Registry Office of one of the districts in Indonesia. The sampling technique used was total sampling, due to the considerably smaller amount of the sample size. This study found that compensation and workplace environment could explain job satisfaction variables with a 93.8% confidence level and simultaneously compensation, workplace environment, and job satisfaction that could explain organizational commitment with a variable of 97.4%. This findings also shows that the manifest bonus variable on the latent compensation variable is one of the main indicators that needs to improve to increase job satisfaction and organizational commitment. One of the important things which needs to be done is to increase compensation. The first thing which needs to be done is to increase the bonus. Furthermore, to improve the quality of the workplace environment, facilities, and infrastructure such as stable internet connections, computer specifications are the important criteria that must be met.

• 한국통신학회논문지
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• 제37권6C호
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• pp.492-496
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• 2012

본 논문은 잡음이 많이 존재할 경우 특징 보상 기법들의 불완전한 추정 방법으로 인하여 발생할 수 있는 불확실성 정보를 음성 인식의 디코딩에 반영해 줌으로써 좀 더 인식 성능을 향상시킬 수 있는 방법에 대한 연구이다. 기존의 특징 보상 기법들은 현재 시간에서의 깨끗한 특징 파라미터를 추정하는 단일점 추정 기법들이 대부분이다. 하지만 낮은 SNR 환경에서의 잘못된 추정 파라미터들이 음성 인식 엔진의 입력으로 사용될 경우 성능이 저하되기 때문에 추정된 파라미터의 불확실성 정보를 이용하여 디코딩을 해주면 추정 오류를 보완해줄 수 있다. 본 논문에서는 대표적인 Aurora-2 DB를 활용하여 적용된 기법의 성능 향상을 확인한다.

• KIEAE Journal
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• 제11권2호
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• pp.3-8
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• 2011

This study was carried out for analysing the relationship of environmental factors and the reduction rate of land compensation of six urban development projects near waste landfill sites located in the Seoul metropolitan area. For a close investigation, 24 variables were selected but only 4 environmental variables were identified to have high correlation to the reduction rate of compensation. These are fine particles(PM10), bad smell, the ratio of a greening zone of land and park, and the distance in straight line from the landfill site. Two variables-PM10 and bad smell-were found to have an effect on the average reduction rate of land compensation by correlation analysis. On the other hand, the ratio of a greening zone and the distance in straight line from the landfill site have been rejected for the significance test. The result of regression analysis of six models for the search of affecting variables on the reduction rate of compensation is that PM10 and bad smell have the impact ratio of more than 0.5. But the ratio of greening zone and the distance from the landfill are not significant factors, having the impact ratio of 0.025~0.045 except one model.