• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2004년도 추계학술대회 논문집
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• pp.170-174
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• 2004

Despite the widespread use in the various manufacturing industries, the full automation of the robotic CO$_2$ welding has not yet been achieved partly because the mathematical model for the process parameters of a given welding task is not fully understood and quantified. Several mathematical models to control welding quality, productivity, microstructure and weld properties in arc welding processes have been studied. However, it is not an easy task to apply them to the various practical situations because the relationship between the process parameters and the bead geometry is non-linear and also they are usually dependent on the specific experimental results. Practically, it is difficult, but important to know how to establish a mathematical model that can predict the result of the actual welding process and how to select the optimum welding condition under a certain constraint. In this paper, an attempt has been made to develop an Radial basis function network model to predict the weld top-bead width as a function of key process parameters in the robotic CO$_2$ welding. and to compare the developed model and a simple neural network model using two different training algorithms in order to verify performance. of the developed model.

• 한국항해항만학회지
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• 제42권5호
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• pp.347-356
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• 2018

The presence of the Fourth Industrial Revolution is omniscient, led by full force emergence of technologies that make biological, physical, and digital worlds borderless. All industries which jump on the bandwagon, can observe convergence and merging of bushiness happening within, between and across industries. As the shipping and port logistics industry is said to be in eye of this storm, the purpose of this study is to investigate the shipping and port logistics industry's awareness regarding 4th IR, as well to identify necessary countermeasures in responding to progression of this trend. Analytic Hierarchy Process (AHP) methodology was then used to compare the importance of four phases of countermeasures, reviewed by experts in the field. Results showed that countermeasures should be first orchestrated to the 'Merging and Integration of Inter-industry', then followed by 'P reemptive Introduction of Advanced Technology', 'Expansion of Intra-industry Businesses', and eventually 'Automation, Unmanned Technology'. Last but not least, four phases of countermeasures which should be introduced and executed one phase after another, are outlined for the shipping and port logistics industry to boost its competitiveness in addressing this progressive trend.

• 한국소음진동공학회논문집
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• 제15권2호
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• pp.148-155
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• 2005

As functional requirement of massive digital information storage devices are on a trend for the higher data transfer rate and lower cost, many different technical efforts are being tested and implemented in the industry. FDB(fluid dynamic bearing) is one of the major breakthroughs in rotor design in terms of TMR(track misregistration) budget. Although FDB analysis based on Reynolds' equation is well established and popularly being used for FDB design especially for the estimation of bearing stiffness, there are obvious limitations in the approach due to the inherent assumptions. A generalized analysis tool employing the full Navier-Stokes equation and the energy balance is to be beneficial for detailed FDB design. In this publication, an efficient geometry modeling method is presented that provides fully integrated inputs for general FVM/FDM(finite volume method/ finite difference method) codes. By virtue of the flexibility of the presented method, many different detailed FDB design and analysis are carried over with ease.

• The Journal of the Acoustical Society of Korea
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• 제14권2E호
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• pp.33-36
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• 1995

CELP 보코더에서의 피치검색에 있어서, 음성신호의 상관함수의 몇가지 특성을 이용한 스킵기법은 음질의 저하를 거의 일으키지 않으면서 피치검색에 필요한 계산량을 줄여준다. 하지만, 때때로 양의 상관값을 갖는 검색대상피치들이 검색에서 제외되어 음질이 저하되는 것을 완전히 막을 수는 없다. 이러한 단점을 보완하기 위해서 약식의 상관함수식을 이용한 개선된 스킵기법을 제안한다. 제안된 방법을 기존의 전체검색방법보다 계산량을 35% 이상 줄이면서도 음절이 저하는 일어나지 않는다.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2005년도 춘계학술대회 논문집
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• pp.66-70
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• 2005

The full automation of welding has not yet been achieved partly because the mathematical model for the process parameters of a given welding task is not fully understood and quantified. Several mathematical models to control welding quality, productivity, microstructure and weld properties in arc welding processes have been studied. However, it is not an easy task to apply them to the various practical situations because the relationship between the process parameters and the bead geometry is non-linear and also they are usually dependent on the specific experimental results. Practically, it is difficult, but important to know how to establish a mathematical model that can predict the result of the actual welding process and how to select the optimum welding condition under a certain constraint. In this paper, an attempt has been made to develop an neural network model to predict the weld top-bead height as a function of key process parameters in the welding. and to compare the developed model and a simple neural network model using two different training algorithms in order to select an optimal neural network model.

• 한국광학회지
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• 제18권2호
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• pp.130-134
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• 2007

광역의 자유곡면 형상을 나노미터 정밀도로 측정하기 위한 새로운 형상 측정법으로서 곡률에 근거한 형상 측정법을 제안한다. 곡률 형상 측정기는 피측정물을 일정간격으로 스캔하는 간섭계로써 각 국부영역의 형상으로부터 곡률을 획득하여, 이로부터 전 영역의 형상을 복원한다. 제안된 곡률 형상 측정기는 비구면 형상 측정을 위해 개발된 보상 광학계(Null optics)나 국부영역의 형상을 측정하고 결합하는 subaperture-slicking 법에 비해 측정 장비로부터 발생하는 시스템 오차를 근본적으로 제거하는 특징을 가진다. $80mm\times80mm\times25mm$ 작동구간을 갖는 Stewart Platform과 상용 트와이만 그린 간섭계를 이용하여 곡률간섭계를 구성하였으며, 자유곡면의 형상측정을 위한 첫 단계로서 잘 알려진 구면형상을 측정하고, 기존 장비의 측정값과 비교한 결과 32 mm영역에서 최대 56 nm의 차를 보임을 확인하였다.

• 한국표면공학회지
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• 제40권4호
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• pp.185-189
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• 2007

A scanning electron microscope (SEM) is a complex system, consisting of many sophisticated components. For a systematic characterization, a $2^4$ full factorial experiment was conducted. The SEM components examined include condenser lens 1 and 2 (denoted as A and B, respectively), and Objective lens (coarse and fine-denoted as C and D respectively). A statistical analysis was conduced to investigate factor effects and variations In response surfaces. Among four factors, main effect analysis revealed that A and D were Identified as the dominant factor. Moreover, B showed conflicting effect against C. The $R^2$ of statistical regression model constructed was about 69.6%. The model generated 3D response surface plots facilitated understanding of complex tactor effects.

• 정보기술과데이타베이스저널
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• 제1권1호
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• pp.31-62
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• 1994

Information systems for application areas like office automation, customer service or computer aided manufacturing are usually highly interactive and deal with complex document structures composed of multiple media formats. For the realization of these systems, nonstandard database systems, which we call document databases, need to handle different types of coarse-and fine-grained document objects(like full-text documents, graphics and images), hierarchical and non-hierarchical relationships between objects(like composition-links and cross-references using hypertext structures) and document attributes of different types such as formatting/presentation information and access control. In this paper, we present the underlying data model for document databases based on descriptive markup languages that provide mechanisms for specifying the logical structure(or schema) of individual documents stored in the database. We then describe extensions to the data model for supporting notion of composite structures("join" operators for documents) --composition and hyperlinking mechanisms for representing compound documents and inter-linked documents as unique entites separate from their components. Furthermore, due to the interactive nature of the application domains, the database system in conjunction with clients(or browsers) has to support visual navigation and graphical query mechanisms. We describe the functionality of a new user interface paradigm called HyBrow for meeting the above mentioned requirements. The underlying implementation strategy is also discussed.discussed.

• Smart Structures and Systems
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• 제21권5호
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• pp.687-694
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• 2018

The problem of wheel tread defects has become a major challenge for the health management of high-speed rail as a wheel defect with small radius deviation may suffice to give rise to severe damage on both the train bogie components and the track structure when a train runs at high speeds. It is thus highly desirable to detect the defects soon after their occurrences and then conduct wheel turning for the defective wheelsets. Online wheel condition monitoring using wheel impact load detector (WILD) can be an effective solution, since it can assess the wheel condition and detect potential defects during train passage. This study aims to develop an FBG-based track-side wheel condition monitoring method for the detection of wheel tread defects. The track-side sensing system uses two FBG strain gauge arrays mounted on the rail foot, measuring the dynamic strains of the paired rails excited by passing wheelsets. Each FBG array has a length of about 3 m, slightly longer than the wheel circumference to ensure a full coverage for the detection of any potential defect on the tread. A defect detection algorithm is developed for using the online-monitored rail responses to identify the potential wheel tread defects. This algorithm consists of three steps: 1) strain data pre-processing by using a data smoothing technique to remove the trends; 2) diagnosis of novel responses by outlier analysis for the normalized data; and 3) local defect identification by a refined analysis on the novel responses extracted in Step 2. To verify the proposed method, a field test was conducted using a test train incorporating defective wheels. The train ran at different speeds on an instrumented track with the purpose of wheel condition monitoring. By using the proposed method to process the monitoring data, all the defects were identified and the results agreed well with those from the static inspection of the wheelsets in the depot. A comparison is also drawn for the detection accuracy under different running speeds of the test train, and the results show that the proposed method can achieve a satisfactory accuracy in wheel defect detection when the train runs at a speed higher than 30 kph. Some minor defects with a depth of 0.05 mm~0.06 mm are also successfully detected.

• 디지털융복합연구
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• 제14권11호
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• pp.91-100
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• 2016

본 연구는 퍼지이론을 이용하여 신규 건설중인 인천항 신국제여객터미널의 항만운영 성공요인 도출을 연구의 목적으로 하였다. 항만운영 성공요인은 카페리선사와 항만하역사에 종사하는 임직원을 대상으로 1차적으로 설문조사를 진행한 후, 한중카페리 선사 및 해당 하역사의 근무경력 15년 이상 전문가와 심층인터뷰(Indepth-Interview)를 수행하여 최종적으로 선정하였다. 전문가의 지식 추출이 가능한 퍼지방법을 활용하여 성공적 항만운영 요인에 대한 가중치를 산정하였다. 신국제여객터미널을 이용하게 될 선사와 하역사들을 대상으로 "부지 사용적 측면", "생산성 측면", "비용적 측면", "항만서비스 측면"으로 상위평가요인을 분류하여 항만운영의 성공요인을 비교분석하였다. 분석결과 "부지사용적 측면"은 컨테이너장치장 확보(0.857)가 가장 중요한 요소로 나타났으며, "생산성 측면"에서는 터미널의 자동화 시스템 구축(0.806)이 가장 중요하게 분석되었다. "비용적 측면"과 "서비스적 측면"에서는 부지 임대료 산정(0.861)과 선석스케쥴 관리(0.798)가 각각 가장 중요한 요인으로 나타났다. 결론적으로 신국제여객터미널은 적정임대료 산정, CY장치장 적정면적 확보, 터미널의 자동화 시스템 구축 등에 주력하여 항만운영을 해야 한다는 시사점을 지니며 향후 동일 운영형태의 국제여객터미널 비교분석 연구를 진행할 필요성이 존재한다.