• The Journal of Asian Finance, Economics and Business
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• 제6권4호
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• pp.179-187
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• 2019

This study aims to investigate the effects of market commonality and resource similarity on price competition and the recursive consequences in the Korean lodging market. Price comparison among hotels in the same geographic market has been facilitated through the development of information technology, rendering little search cost of consumers. While the literature implies the heterogeneous price attack and response among hotels, a limited number of empirical researches focus on the asymmetric and recursive pattern in the competitive dynamics. This study empirically examines the price interactions in the Korean lodging market based on the theoretical framework of competitive price interactions and countervailing power. Demonstrating superiority to the spatial lag model and the ordinary least squares in the estimation, the results from spatial error model suggest that the hotels with longer operational history pose an asymmetric impact on the price of the newer hotels. The asymmetry is also found in chain hotels over the independent, further implying the possibility of predatory pricing. The findings of this study provide the evidence of a hierarchical structure in the price competition, with different countervailing power by the resources of the hotels. Theoretical and managerial implications are discussed, with suggestions for future study.

• 한국멀티미디어학회논문지
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• 제15권11호
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• pp.1391-1398
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• 2012

무선 센서네트워크에서의 시각동기는 Wireless USB, WBAN 등의 MAC 계층에서부터 응용 계층에 이르기까지 거의 모든 계층에서 다양한 목적을 위해 매우 중요한 기술이다. 본 논문에서는 무선 센서네트워크에서의 시각동기를 위한 실시간 클럭 스큐 추정 방법을 제시한다. 재귀적 최소제곱법을 통해 오프셋 보정 정보들을 얻을 때마다 클럭 스큐가 실시간적으로 추정 및 갱신되며, 아울러 스큐 추정을 위해 각 센서노드에 저장해야할 정보를 최소화한다. 제안한 클럭 스큐 추정 방법은 기존의 클럭 오프셋 보정 방법과 쉽게 통합될 수 있으며, 이 경우 보다 정확하고 효율적인 시각동기화가 가능해진다. 시뮬레이션 및 실험 결과를 통해 제안한 클럭 스큐 추정 방법을 통한 시각동기 정확도의 향상을 보인다.

• 한국항행학회논문지
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• 제16권4호
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• pp.586-592
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• 2012

비선형 시스템을 제어하는 효과적인 방법으로 신경망과 연동된 퍼지구조를 적용한 ANFIS 제어기를 이용되고 있다. 전통적인 ANFIS에서는 다차원의 입력에도 불구하고 단일출력에 대한 공정을 모델링하고 제어 하는데 사용된다. 멤버쉽 함수의 파라미터는 최소자승예측과 역전파 알고리즘을 이용하여 조정된다. 이동로봇의 경우에는 좌측과 우측의 바퀴를 각각 구동할 필요가 있다. 본 논문에서는 이동로봇의 궤적을 추적하기 위하여 2-입력 2-출력을 가진 ANFIS제어기를 적용한 제어시스템 구조를 제안하였다. 시뮬레이션을 통하여 제안된 구조가 이동로봇에 대한 가능한 제어기임을 확인할 수 있었다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1996년도 한국자동제어학술회의논문집(국내학술편); 포항공과대학교, 포항; 24-26 Oct. 1996
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• pp.1352-1355
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• 1996

The control of diamond turning is usually achieved through a laser-interferometer feedback of slide position. If the tool post is rigid and the material removal process is relatively static, then such a non-collocated position feedback control scheme may surface. However, as the accuracy requirement gets tighter and desired surface contours become more complex, the need for a direct tool-tip sensing becomes inevitable. The physical constraints of the machining process prohibit any reasonable implementation of a tool-tip motion measurement. It is proposed that the measured force normal to the face of the workpiece can be filtered through an appropriate admittance transfer function to result in the estimated depth of cut. This can be compared to the desired depth of cut to generate the adjustment control action in addition to position feedback control. In this work, the design methodology on the admittance model-based control with a conventional controller is presented. The recursive least-squares algorithm with forgetting factor is proposed to identify the parameters and update the cutting process in real time. The normal cutting forces are measured to identify the cutting dynamics in the real diamond turning process using the precision dynamometer. Based on the parameter estimation of cutting dynamics and the admittance model-based nanodynamic control scheme, simulation results are shown.

• 농업과학연구
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• 제32권2호
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• pp.151-167
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• 2005

In this study, certain factors influencing cherry tomato were estimated using system equations. In addition, the amount of influence to income from each factor was estimated from both direct and indirect effects. Based on OLS(Ordinary Least Squares) estimation, path analysis and factor analysis were employed to overcome multicollinearity problems. Data used in this study is interviewed cross sectional data of 65 cherry tomato producing farm in Chungnam-do area. Average age of the producers is 46.5. Average year of the production is 8 years. Average farm size, productivity, and income are 1,123 pyong, 7,439kg/10a, 8,112,000won/10a, respectively. The business performance of the sample farms were above average, in terms of the diagnosis by "Standard Business Diagnosis for Cherry tomato". To identify the factors influencing productivity, 15, 19, and 25 independent variables were selected for the dependent variables of yield, price(quality), and business cost, respectively. Finally, yield, quality, and business cost variables were set as independent variables to explain income as dependent variable. As a result of main factor analysis, 10, 12, 15, and 16 factors were identified as main factors for yield, quality, business cost, and income, respectively.

• 한국해양공학회지
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• 제22권4호
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• pp.97-105
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• 2008

This paper represents the experimental identification of a finite-dimensional dynamical plant model for the HEMIRE Remotely Operated Vehicle. The experiments were conducted during sea trials in the East Sea in October 2006 and peer testing by the South Sea Research Institute in January 2007. A least-squares method was employed to identify decoupled single degree-of-freedom plant dynamical models for the X, Y, Z and heading degree-of-freedom from experimental data. The performance of the identified plant dynamical model was evaluated by directly comparing simulations of the identified plant model to the experimentally observed motion data from the actual vehicle.

• 대한기계학회논문집A
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• 제35권11호
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• pp.1423-1428
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• 2011

본 논문은 비선형 구동기를 포함한 유연시스템의 잔류변위저감을 위한 학습입력성형제어기를 제시한다. 제시되는 제어기는 비선형 구동기에 대한 입력성형제어기, 반복최소자승법 및 설계변수 updating rule 을 통합하여 개발된다. 비선형 구동기에 대응한 입력성형제어기 설계변수의 updating mechanism 을 개선하기 위한 잔류변위 측정함수가 제시된다. 제시된 제어방법을 pendulum system 에 적용하여 변수추정의 수렴성과 변위저감제어성능의 평가를 통해 수치해석적으로 실용성이 검증된다.

• Asian-Australasian Journal of Animal Sciences
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• 제15권2호
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• pp.166-171
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• 2002

The main objective of the present study is to estimate the crossbreeding parameters in respect to serum lysozyme level in broilers. The experiment involved a complete $4{\times}4$ diallel design using four synthetic broiler lines namely Coloured Synthetic Male Line (CSML), White Synthetic Male Line (WSML), Coloured Synthetic Female Line (CSFL) and Naked Neck Line (NNL). The lyophilised Micrococcus lysodeikticus suspension was used to detect the lysozyme level in the serum of birds. The data were analysed by least-squares method to find the effects of genetic and non-genetic factors using appropriate model. The crossbreeding parameters for this trait were estimated by complete diallel model assuming the effect of each synthetic line as fixed. The results indicated that additive and non-additive genetic variation attributed to minor genes at many loci is important for the genetic control of serum lysozyme level in chickens. Total non-additive components of variance also showed significant amount of heterosis in crossbred progenies, and therefore exploitation of non-additive component of variance is possible for improvement in serum lysozyme level in broilers. The overall results suggested that for commercial broiler production system, the selection for specialised line on the basis of serum lysozyme level and subsequent crossing of parent lines could enhance the immunocompetence status in relation to serum lysozyme level in crossbred chickens.

• Journal of Power Electronics
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• 제16권5호
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• pp.1981-1989
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• 2016

Battery diagnosis is vital to battery-based applications because it ensures system reliability by avoiding battery failure. This paper presents a novel intelligent battery charger with an online diagnosis function to circumvent interruptions in system operation. The charger operates in normal charging and diagnosing modes. The diagnosis function is performed with the impedance spectroscopy technique, which is achieved by injecting a sinusoidal voltage excitation signal to the battery terminals without the need for additional hardware. The impedance spectrum of the battery is calculated based on voltage excitation and current response with the aid of an embedded digital lock in amplifier in a digital signal processor. The measured impedance data are utilized in the application of the complex nonlinear least squares method to extract the battery parameters of the equivalent circuit. These parameters are then compared with the reference values to reach a diagnosis. A prototype of the proposed charger is applied to four valve-regulated lead-acid batteries to measure AC impedance. The results are discussed.

• Journal of Information Processing Systems
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• 제10권3호
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• pp.395-411
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• 2014

Temporal medical data is often collected during patient treatments that require personal analysis. Each observation recorded in the temporal medical data is associated with measurements and time treatments. A major problem in the analysis of temporal medical data are the missing values that are caused, for example, by patients dropping out of a study before completion. Therefore, the imputation of missing data is an important step during pre-processing and can provide useful information before the data is mined. For each patient and each variable, this imputation replaces the missing data with a value drawn from an estimated distribution of that variable. In this paper, we propose a new method, called Newton's finite divided difference polynomial interpolation with condition order degree, for dealing with missing values in temporal medical data related to obesity. We compared the new imputation method with three existing subspace estimation techniques, including the k-nearest neighbor, local least squares, and natural cubic spline approaches. The performance of each approach was then evaluated by using the normalized root mean square error and the statistically significant test results. The experimental results have demonstrated that the proposed method provides the best fit with the smallest error and is more accurate than the other methods.